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Sample records for sandstone facies texas

  1. Facies architecture of tidal shelf sandstone ridge: Tocito sandstone

    SciTech Connect

    Riley, G.W.; Nummedal, D. )

    1989-09-01

    The lithofacies architecture of a single Tocito Sandstone Lentil has been documented in outcrops near the Hogback oil field west of Farmington with a very detailed outcrop study. This isolated Tocito sand body is composed of a three-tiered hierarchy of linear ridge elements. The large-scale Tocito Sandstone Lentil is approximately 5 km wide, 30 km long, and up to 16 m thick. The lentil is composed of at least three smaller scale ridges, which are up to 1 km wide, of unknown length, and up to 16 m thick. The small-scale ridges are arranged such that each new ridge accreted on the landward margin of the previous ridge. These smaller scale ridges consist of an ordered arrangement of four basic lithofacies: (1) burrowed, muddy sandstone, (2) interbedded clean and muddy sandstone, (3) cross-bedded sandstone, and (4) ripple-bedded sandstone. burrowed, muddy sandstone is found at the base of the small-scale ridges, is laterally extensive, and is interpreted as forming downcurrent from the most active portion of the ridge. The cross-bedded sandstone forms ribbon-shaped sand bodies elongate in the direction of ridge elongation. Typically the sand ribbons are 100-300 m wide, 2-4 m thick, and up to 1 km long. Usually two or more combine to form a small-scale ridge. The interbedded sandstone is found above the cross-bedded lithofacies as well as between the sand ribbons. The ripple-bedded facies is always found at the top of the section and represents the waning stage of ridge growth. The resulting architecture is one of coalesced sand ribbons combining to form the small-scale ridges, and subsequently small-scale ridges accreting landward to form a composite Tocito Sandstone Lentil.

  2. Dakota sandstone facies, western Oklahoma panhandle

    SciTech Connect

    Atalik, E.; Mansfield, C.F.

    1984-04-01

    The Cretaceous Dakota Sandstone in Cimarron County comprised three sandstone units and intervening mudrocks; it overlies the Kiowa Shale Member of the Purgatoire Formation. Deposits include shoreface, beach (foreshore) and dune, estuarine and tidal channel, marine marginal bay and swamp/marsh in a generally progradational sequences associated with marine regression in the Western Interior. The shoreface sand, characterized by ripple lamination, bioturbation and the trace fossils Teichichnus and Thalassinoides, is fine-grained, 5-10 m (15-30 ft) thick and grades into the underlying Kiowa Shale. Beach and associated dune deposits are 2-5 m (6-16 ft) thick, medium to fine-grained, medium to thick-bedded, tabular-planar cross-bedded, and lenticular; cross-bed paleocurrent headings are northeasterly and northwesterly. Estuarine channel deposits are 3-5 m (10 to 16 ft) thick, trough to tabular-planar cross-bedded, and medium to coarse-grained with local conglomerate overlying the scoured base which commonly cuts into the Kiowa Shale or overlying shoreface sandstone; rip-up clasts and wood pieces are common but trace fossils are rare; southeasterly and southwesterly paleocurrents predominate. Tidal channel deposits are thinner (up to 2 m of 6 ft) and finer grained (medium to fine-grained) that the estuarine channel deposits; they occur within fine-grained sandstone and mudrock sequences, are trough cross-bedded, and commonly contain trace fossils (e.g., Skolithos) and wood fragments. Marine marginal (tidal flat or bay.) deposits comprise fine-grained sandstone, siltstone and interbedded shale, that are 1-3m (3-10 ft) thick with abundant burrows, small ripple marks, and parallel lamination. These grade into the fine to very fine-grained sandstones, siltstones, shales, and coals of the swamp/marsh deposits that are 1-5m (3-16 ft) thick and contain ripple marks, burrows, other trace fossils, and parallel lamination.

  3. Depositional facies, diagenesis, and reservoir quality of Ivishak sandstone (Sadlerochit Group), Prudhoe Bay field

    SciTech Connect

    McGowen, J.H.; Bloch, S.

    1985-02-01

    The Sadlerochit Group is a large fan-delta system comparable in size to the modern Kosi River wet alluvial fan of Nepal and India. Braided-stream processes distributed chert gravel and quartz and chert sand in radial fashion to construct the subaerial part of the fan delta. Fluvial energy, slope of the fan surface, and grain size decrease in a north to south basinward direction. There is also a decrease in scale of sedimentation units from source area seaward. Facies of the subaerial fan delta can be broadly categorized as midfan delta (alternating conglomerate and sandstone), distal fan-delta (chiefly sandstone), and abandoned channel-fill, overbank, and pond facies (mudstone, siltstone, fine-grained sandstone). Seaward of the subaerial fan delta are the delta-front and prodelta facies. Subaerial fan-delta and delta-front facies compose the Ivishak sandstone, which grades basinward into the Kavik shale, a prodelta facies. Diagenetic effects were gradually superimposed on the sediments deposited in the Sadlerochit fan-delta system. The sedimentary facies, and in particular their textural characteristics, seem to control the side and degree of diagenesis, including enhancement of porosity and permeability. Comparison of permeability trends among the facies of the Ivishak sandstone with permeability patterns displayed by unconsolidated sands with analogous grain size and texture, indicates that the general trends that existed in the Ivishak sediments are still recognizable in spite of the diagenetic overprint.

  4. Facies analysis and petroleum potential of Smackover Formation, western and northern areas, East Texas basin

    SciTech Connect

    Hancharik, J.M.

    1983-03-01

    The Smackover Formation (Upper Jurassic) in northeast Texas is a transgressive-regressive carbonate sequence which has been extensively dolomitized. The Smackover Formation is subdivided informally into a lower and upper member based on distinctive lithologic characteristics. The lower member, which rests conformably on the fluvial-deltaic sandstones of the Upper Jurassic Norphlet Formation, contains a laminated, organic carbonate mudstone facies that grades into an overlying locally fossiliferous, pelletalmicritic facies. The upper member of the Smackover Formation consists mainly of broken skeletal debris and pelletal allochems in a micritic matrix. The sediments are better winnowed and better sorted upward in the sequence. Interbedded with and overlying the skeletal-pelletal facies is a clean well-sorted dolomitized oolitic-grainstone facies. This upper-most informal member marks the beginning of a progradational sequence which lasts throughout the remainder of Smackover deposition and continues through deposition of the evaporities and red beds of the overlying Buckner Formation. Most of the Smackover production in northeast Texas occurs along the Mexia-Talco fault zone in the deeper gentle salt-related anticlines and salt-graben systems. Reservoir rocks are primarily leached and dolomitized oolitic grainstones and dolomite. Laminated organic carbonate mudstones which characterize the lower, transgressive phase of the Smackover Formation provide an excellent source rock for petroleum. Exploration targets for the Smackover Formation are the areas were dolomitized oolitic and skeletal grainstones occur on top of structurally high areas such as over salt ridges or swells in the deeper portions of the basin.

  5. Core facies, petrology, and permeability of Tirrawarra Sandstone, Moorari Field, Cooper Basin, South Australia

    SciTech Connect

    Bever, J.M.; Carroll, P.G.; Wild, E.W.; Williams, B.P.J.

    1988-01-01

    The oil and gas-bearing Tirrawarra Sandstone lies in the basal section of the Cooper basin sequence, which is largely Permian in age. The sandstone is characteristically thick, but both interfingers with and conformable overlies glacio-lacustrine diamictites and varvites of the late Carboniferous-Early Permian Merrimeleia Formation. The Tirrawarra Sandstone has previously been interpreted as being deposited in a glacio-fluvial braided river environment. The sandstone produces high gas:oil-ratio oil at the Moorari field, from depths of 9,400 ft below sea level. Appraisal and development of the field has been hampered by the patchy distribution of reservoir quality sandstone. This study investigated the cause of reservoir quality variations. For seven cored wells, core facies analysis, core plug porosity/permeability, petrology, and wireline logs were all matched and compared. The results are as follows. (1) Facies states (grain size and bed form) largely control permeability distribution in the Tirrawarra Sandstone at the Moorari field, such that horizontally bedded medium-coarse sandstones are consistently more permeable than cross-bedded equivalents. (2) Diagenesis levels are high and include extensive silica cement and patchy kaolinite and siderite cements. However, diagenesis rarely operates independently of original depositional fabric. (3) An association between depositional environment and permeability is recognizable, with medial bars in particular providing better reservoir quality.

  6. Facies-controlled fluid migration patterns and subsequent reservoir collapse by depressurization - the Entrada Sandstone, Utah

    NASA Astrophysics Data System (ADS)

    Sundal, A.; Skurtveit, E.; Midtkandal, I.; Hope, I.; Larsen, E.; Kristensen, R. S.; Braathen, A.

    2016-12-01

    The thick and laterally extensive Middle Jurassic Entrada Sandstone forms a regionally significant reservoir both in the subsurface and as outcrops in Utah. Individual layers of fluvial sandstone within otherwise fine-grained aeolian dunes and silty inter-dune deposits of the Entrada Earthy Member are of particular interest as CO2 reservoir analogs to study injectivity, reservoir-caprock interaction and bypass systems. Detailed mapping of facies and deformation structures, including petrographic studies and core plug tests, show significant rock property contrasts between layers of different sedimentary facies. Beds representing fluvial facies appear as white, medium-grained, well-sorted and cross-stratified sandstone, displaying high porosity, high micro-scale permeability, low tensile strength, and low seismic velocity. Subsequent to deposition, these beds were structurally deformed and contain a dense network of deformation bands, especially in proximity to faults and injectites. Over- and underlying low-permeability layers of inter-dune aeolian facies contain none or few deformation bands, display significantly higher rock strengths and high seismic velocities compared to the fluvial inter-beds. Permeable units between low-permeability layers are prone to become over-pressured during burial, and the establishment of fluid escape routes during regional tectonic events may have caused depressurization and selective collapse of weak layers. Through-cutting, vertical sand pipes display large clasts of stratified sandstone suspended in remobilized sand matrix, and may have served as permeable fluid conduits and pressure vents before becoming preferentially cemented and plugged. Bleached zones around faults and fractures throughout the succession indicate leakage and migration of reducing fluids. The fluvial beds are porous and would appear in wireline logs and seismic profiles as excellent reservoirs; whereas due to dense populations of deformation bands they may in

  7. Facies and stratigraphy of the Pennsylvanian Warren Point Sandstone, central Cumberland Plateau, Tennessee

    SciTech Connect

    Hurd, S.A.; Stapor, F.W. Jr. . Earth Sciences Dept.)

    1994-03-01

    The Warren Point Sandstone is a fine-grained, quartz arenite composed primarily of the following three facies: planar bedded 2-D cross beds, low angle cross beds, and broad, shallow channel-fills. Ripple cross lamination, horizontal lamination, and laminated shale facies are also observed. These facies units are grouped into four of Miall's major architectural elements: sandy bedforms, channels, laminated sand sheets, and overbank fines. Paleocurrent measurements made on the 2-D cross beds indicate southwest transport. Throughout this region the Warren Point occurs as a nearly continuous and essentially homogeneous, 7--12 m-thick, sandstone sheet. The authors interpret a sandy braid plain depositional environment for the Warren Point. Initial sand composition data suggest a foreland uplift provenance that along with the southwest transport indicate the Alleghenian orogen as the probable source. The Warren Point disconformably overlies each of it's two stratigraphically subjacent units: the Pennsylvanian Raccoon Mountain (0--5 m-thick) and the upper limestone member of the Mississippian Pennington formations. The Sewanee Conglomerate disconformably overlies the Warren Point and, near Spencer, TN, rests directly on the Pennington limestone member that was a topographic high during Warren Point deposition. The absence of underlying shelfal and marginal marine Pennsylvanian siliciclastics in conjunction with the Warren Point's basal disconformity suggests a sea-level fall that resulted in a basinward facies shift.

  8. Reservoir heterogeneity in middle Frio fluvial sandstones: Case studies in Seeligson field, Jim Wells County, Texas

    SciTech Connect

    Jirik, L.A. )

    1990-09-01

    Detailed evaluation of middle Frio (Oligocene) fluvial sandstones reveals a complex architectural style potentially suited to the addition of gas reserves through recognition of poorly drained reservoir compartments and bypassed gas zones. Seeligson field is being studied as part of a Gas Research Institute/US Department of Energy/State of Texas-sponsored program, with the cooperation of Oryx Energy Company and Mobil Exploration and Producing US, Inc. Four reservoirs, Zones 15, 16D, 16E, and 19C, were studied in a 20 mi{sup 2} area within Seeligson field. Collectively, these reservoirs have produced more than 240 bcf of gas from wells within the study area. Detailed electric log correlation of individual reservoirs enabled subdivision of aggregate producing zones into component genetic units. Cross sections, net-sandstone maps, and log-facies maps were prepared to illustrate depositional style, sand-body geometry, and reservoir heterogeneity. Zones 15 and 19C are examples of laterally stacked fluvial architecture. Individual channel-fill sandstones range from 10 to 50 ft thick, and channel widths are approximately 2,500 ft. Crevasse-splay sandstones may extend a few thousand feet from the main channel system. Multiple, overlapping channel and splay deposits commonly form sand-rich belts that result in leaky reservoir compartments that may be incompletely drained. Zones 16D and 16E are examples of vertically stacked fluvial architecture, with discrete, relatively thin and narrow channel and splay sandstones generally encased within floodplain muds. This architectural style is likely to form more isolated reservoir compartments. Although all of these reservoirs are currently considered nearly depleted, low-pressure producers, recent well completions and bottomhole pressure data indicate that untapped or poorly drained compartments are being encountered.

  9. Fluvial architecture and reservoir heterogeneity of middle Frio sandstones, Seeligson field, Jim Wells and Kleberg Counties, south Texas

    SciTech Connect

    Jirik, L.A.; Kerr, D.R.; Zinke, S.G.; Finley, R.J. )

    1990-05-01

    Evaluation of fluvial Frio reservoirs in south Texas reveals a complex architectural style potentially suited to the addition of incremental gas reserves through recognition of untapped compartments or bypassed gas zones. Seeligson field is being studied as part of a GRI/DOE/Texas-sponsored program, in cooperation with Oryx Energy Company and Mobil Exploration and Production U.S., Inc., and is designed to develop technologies and methodologies for increasing gas reserves from conventional reservoirs in mature fields. Seeligson field, discovered in 1937, has produced 2.2 tcf of gas from more than 50 middle Frio reservoirs. Cross sections as well as net sand and log facies maps illustrate depositional style, sandstone geometry, and reservoir heterogeneities. Far-offset vertical seismic profiles show laterally discontinuous reflections corresponding to the reservoirs. Lenticular lateral-bar sandstones dominate channel-fill deposits that together are commonly less than 50 ft thick, forming belts of sandstone approximately 2,500 ft wide. Crevasse-splay deposits commonly extend a few thousand feet beyond the channel system. Sand-rich channel-fill deposits are flanked by levee and overbank mudstones, isolating the reservoirs in narrow, dip-elongate trends. Deposition on an aggrading coastal plain resulted in a pattern of laterally stacked sandstone bodies that are widespread across the study area. Alternating periods of more rapid aggradation resulted in deposition of vertically stacked sandstones with limited areal distribution. Facies architecture of both depositional styles has implications for reservoir compartmentalization. Reservoir compartments within a laterally stacked system may be leaky, resulting from sandstone contact from producing wells along depositional axes. This effect is a major factor controlling incremental recovery. Reservoirs in vertically stacked systems should be better isolated.

  10. Consolidation of geologic studies of geopressured-geothermal resources in Texas: Barrier-bar tidal-channel reservoir facies architecture, Jackson Group, Prado field, South Texas; Final report

    SciTech Connect

    Seni, S.J.; Choh, S.J.

    1994-01-01

    Sandstone reservoirs in the Jackson barrier/strandplain play are characterized by low recovery efficiencies and thus contain a large hydrocarbon resource target potentially amenable to advanced recovery techniques. Prado field, Jim Hogg County, South Texas, has produced over 23 million bbl of oil and over 32 million mcf gas from combination structural-stratigraphic traps in the Eocene lower Jackson Group. Hydrocarbon entrapment at Prado field is a result of anticlinal nosing by differential compaction and updip pinch-out of barrier bar sandstone. Relative base-level lowering resulted in forced regression that established lower Jackson shoreline sandstones in a relatively distal location in central Jim Hogg County. Reservoir sand bodies at Prado field comprise complex assemblages of barrier-bar, tidal-inlet fill, back-barrier bar, and shoreface environments. Subsequent progradation built the barrier-bar system seaward 1 to 2 mi. Within the barrier-bar system, favorable targets for hydrocarbon reexploration are concentrated in tidal-inlet facies because they possess the greatest degree of depositional heterogeneity. The purpose of this report is (1) to describe and analyze the sand-body architecture, depositional facies variations, and structure of Prado field, (2) to determine controls on distribution of hydrocarbons pertinent to reexploration for bypassed hydrocarbons, (3) to describe reservoir models at Prado field, and (4) to develop new data affecting the suitability of Jackson oil fields as possible candidates for thermally enhanced recovery of medium to heavy oil.

  11. Clarksville field Red River County, Texas: Production and facies interpretation

    SciTech Connect

    Reed, C.H. )

    1991-03-01

    The Clarksville field was discovered in December in 1985 while targeting a deeper paleozoic horizon. Since production went on line in 1986, this field has produced over 1 million barrels of oil (MMBO) with the appearance of a considerably longer and more lucrative life. The producing horizon is a Jurassic-age lithic conglomerate sitting unconformably on the Paleozoic and Triassic structural front of the buried Ouachita range. Facies correlation out of the basin indicate this unit to be Louark age. Mapping and compositional analysis indicate the depositional environmental of this unit to be an arid climate alluvial fan deposited as a 'Bajada' complex. This fan system was laid down at the updip margin of the actively forming Mesozoic embayment where it meets the Ouachita structural front. The significance of this field is demonstrated by the production yield at a relatively shallow depth (5800 ft). At this time, production similar to Clarksville field has yet to be encountered anywhere along the Mesozoic rim of the East Texas basin but does represent a viable exploration trend, in addition to being a gateway for future paleozoic production in the basin.

  12. Diagenetic facies controls on pore structure and rock electrical parameters in tight gas sandstone

    NASA Astrophysics Data System (ADS)

    Liu, Hongping; Zhao, Yanchao; Luo, Yang; Chen, Zhaoyou; He, Sheng

    2015-08-01

    Rock electrical parameters of tight gas sandstone show large variations in the T2 member in Dingbei Block, Ordos Basin, China. Applying the same rock electrical parameters in water saturation calculations would lead to large errors. Based on casting thin sections, x-ray diffraction, scanning electron microscopy (SEM), cathode luminescence, porosity and permeability, image analysis, and high-pressure mercury intrusion/withdrawal method, identification of the diagenetic facies are first conducted, and then their pore structure and their relationship with rock electrical parameters are investigated. Five diagenetic facies (A-E), which are identified based mainly on pore types and authigenic minerals, have different pore structure and rock electrical parameters. Conceptual models that incorporate the rock properties of each diagenetic facies have been built, before applying the electrical efficiency theory to explain the values of cementation exponent (m) and saturation exponent (n). A conventional network model, a shunt pore model, a netted pore model, and a dotted line model are utilized to mimic the intergranular pores, authigenic kaolinite intercrystal pores, carbonate-cement dissolution pores, and clay-matrix intercrystal pores, respectively. A decrease of the contents of large pores increases electrical efficiency and therefore reduces m. The saturation exponent, which depends on the distribution of water and gas, can be better understood by applying the different pore models. In the shunt and netted pore models, gas displacement starts from the larger pores and smaller pores provide alternative conduction pathways, hence sustaining electrical efficiency and decreasing n. Clay-matrix intercrystal pores are mainly micropores, since the brine in the rocks are isolated after gas displacement, reducing overall electrical efficiency and dramatically increasing the value of n in the diagenetic facies, which is dominated by clay-matrix intercrystal pores.

  13. Differentiating Detrital and Metamorphic Monazite in Greenschist-Facies Sandstones From the Witwatersrand Supergroup

    NASA Astrophysics Data System (ADS)

    Muhling, J. R.; Rasmussen, B.

    2009-05-01

    Monazite is a robust and reliable geochronometer of low-temperature metamorphic and hydrothermal events. It is a widespread accessory phase in sedimentary rocks metamorphosed at prehnite-pumpellyite to lower greenschist facies grade, and also in a range of hydrothermal ore deposits. Its ability to date multiple fluid-flow events in low-grade metasedimentary belts has been largely neglected, possibly because of a misconception that it is rare in these rocks and possibly because of misidentification of metamorphic monazite grains as detrital. Both detrital and metamorphic monazites are present in sandstone and conglomerate from the Witwatersrand Supergroup but can be distinguished by their occurrence, chemistry and age. Detrital grains were unstable during regional greenschist-facies metamorphism, and show evidence for a number of destructive reactions dependent on bulk rock composition and the original composition of the monazite. In quartz sandstone and conglomerate, detrital grains were present in heavy mineral bands with pyrite, zircon and chromite. The monazite grains have been pseudomorphed by intergrowths of apatite, florencite and Th-silicate, as well as matrix muscovite and chlorite. In some samples, Th-silicate forms only minute specks but in others it forms larger prismatic crystals that comprise up to 2% of some pseudomorphs. These variations may reflect differences in the original compositions of the detrital grains. In other samples detrital monazite cores, dated at 2.8-3.0 Ga, are enclosed within 2.04 Ga metamorphic rims. These composite grains formed by dissolution and reprecipitation of monazite during metamorphism. The cores and rims have distinctly different compositions, and the metamorphic rims show pronounced zoning of REE. In more calcic sandstone monazite occurs in heavy mineral bands with chromite, zircon, rutile, pyrite, apatite, Th-silicate, allanite and baddeleyite. These sandstones are notably rich in Ca-bearing minerals such as epidote

  14. Diagenesis of the sandflat and mudflat facies of the upper Queen Formation, Midland basin, Texas

    SciTech Connect

    Mckone, C.J.; Malicse, A.; Mazzullo, J.M. )

    1991-03-01

    The upper Queen Formation (Permian, Guadalupian) of the Midland basin, Texas, consists of cyclically interbedded clastics and evaporites that were deposited in a fluvial-dominated continental sabkha environment. Fluvial sandflat deposits, consisting of thin units (0.2-5.0 m) of very fine grained arkosic sandstones constitute reservoir horizons, whereas 0.1-1.3 m thick units of coarse siltstones and evaporites of playa-mudflat deposits are nonproductive. This study addresses the diagenetic histories of the reservoir and nonreservoir clastics. The primary porosity of the clastics was first reduced by pore-filling hematitic smectite clay, anhydrite, and dolomite during an early diagenetic phase. Subsequent dissolution of the anhydrite and dolomite by acidic pore-waters created high porosities (mean = 15%) and permeabilities (mean = 70 md) in the sandflat deposits, porosities which were only slightly occluded by later dissolution and reprecipitation of grain-lining smectite. Pore-water movement and subsequent hydrocarbon migration were both controlled by the coarser grain size and lower clay-matrix and silt content of these sandflat deposits. In contrast, the finer grain size and higher clay-matrix and silt content prevented similar dissolution of cements within the mudflat facies, which have significantly lower porosities (mean{lt}10%) and permeabilities (mean{lt}0.1 md). Fluids and gases used in enhanced recovery techniques will follow pathways created by dissolution of anhydrite and dolomite cements within the sandflat facies. However, caution must be used with fluids that can cause swelling of the grain-lining smectite.

  15. Facies architecture of the Bluejacket Sandstone in the Eufaula Lake area, Oklahoma: Implications for the reservoir characterization of the Bartlesville Sandstone

    SciTech Connect

    Ye, Liangmiao; Yang, Kexian

    1997-08-01

    Outcrop studies of the Bluejacket Sandstone (Middle Pennsylvanian) provide significant insights to reservoir architecture of the subsurface equivalent Bartlesville Sandstone. Quarry walls and road cuts in the Lake Eufaula area offer excellent exposures for detailed facies architectural investigations using high-precision surveying, photo mosaics. Directional minipermeameter measurements are being conducted. Subsurface studies include conventional logs, borehole image log, and core data. Reservoir architectures are reconstructed in four hierarchical levels: multi-storey sandstone, i.e. discrete genetic intervals; individual discrete genetic interval; facies within a discrete genetic interval; and lateral accretion bar deposits. In both outcrop and subsurface, the Bluejacket (Bartlesville) Sandstone comprises two distinctive architectures: a lower braided fluvial and an upper meandering fluvial. Braided fluvial deposits are typically 30 to 80 ft thick, and are laterally persistent filling an incised valley wider than the largest producing fields. The lower contact is irregular with local relief of 50 ft. The braided-fluvial deposits consist of 100-400-ft wide, 5-15-ft thick channel-fill elements. Each channel-fill interval is limited laterally by an erosional contact or overbank deposits, and is separated vertically by discontinuous mudstones or highly concentrated mudstone interclast lag conglomerates. Low-angle parallel-stratified or trough cross-stratified medium- to coarse-grained sandstones volumetrically dominate. This section has a blocky well log profile. Meandering fluvial deposits are typically 100 to 150 ft thick and comprise multiple discrete genetic intervals.

  16. Impact of depositional facies on the distribution of diagenetic alterations in the Devonian shoreface sandstone reservoirs, Southern Ghadamis Basin, Libya

    NASA Astrophysics Data System (ADS)

    Khalifa, Muftah Ahmid; Morad, Sadoon

    2015-11-01

    The middle Devonian, shoreface quartz arenites (present-day burial depths 2833-2786 m) are important oil and gas reservoirs in the Ghadamis Basin, western Libya. This integrated petrographic and geochemical study aims to unravel the impact of depositional facies on distribution of diagenetic alterations and, consequently, related reservoir quality and heterogeneity of the sandstones. Eogenetic alterations include the formation of kaolinite, pseudomatrix, and pyrite. The mesogenetic alterations include cementation by quartz overgrowths, Fe-dolomite/ankerite, and illite, transformation of kaolinite to dickite, illitization of smectite, intergranular quartz dissolution, and stylolitization, and albitization of feldspar. The higher energy of deposition of the coarser-grained upper shoreface sandstones combined with less extensive chemical compaction and smaller amounts of quartz overgrowths account for their better primary reservoir quality compared to the finer-grained, middle-lower shoreface sandstones. The formation of kaolin in the upper and middle shoreface sandstones is attributed to a greater flux of meteoric water. More abundant quartz overgrowths in the middle and lower shoreface is attributed to a greater extent of stylolitization, which was promoted by more abundant illitic clays. This study demonstrated that linking the distribution of diagenetic alterations to depositional facies of shoreface sandstones leads to a better understanding of the impact of these alterations on the spatial and temporal variation in quality and heterogeneity of the reservoirs.

  17. Consolidation of geologic studies of geopressured-geothermal resources in Texas: Barrier-bar tidal-channel reservoir facies architecture, Jackson Group, Prado Field, South Texas

    SciTech Connect

    Seni, S.J.; Choh, S.J.

    1993-09-01

    Sandstone reservoirs in the Jackson barrier/strandplain play are characterized by low recovery efficiencies and thus contain a large hydrocarbon resource target potentially amenable to advanced recovery techniques. Prado field, Jim Hogg County, South Texas, has produced over 23 million bbl of oil and over 32 million mcf gas from combination structural-stratigraphic traps in the Eocene lower Jackson Group. Hydrocarbon entrapment at Prado field is a result of anticlinal nosing by differential compaction and updip pinch-out of barrier bar sandstone. Relative base-level lowering resulted in forced regression that established lower Jackson shoreline sandstones in a relatively distal location in central Jim Hogg County. Reservoir sand bodies at Prado field comprise complex assemblages of barrier-bar, tidal-inlet fill, back-barrier bar, and shoreface environments. Subsequent progradation built the barrier-bar system seaward 1 to 2 mi. With the barrier-bar system, favorable targets for hydrocarbon reexploration are concentrated in tidal-inlet facies because they possess the greatest degree of depositional heterogeneity.

  18. Facies and architectural element analysis of a meandering fluvial succession: The Permian Warchha Sandstone, Salt Range, Pakistan

    NASA Astrophysics Data System (ADS)

    Ghazi, Shahid; Mountney, Nigel P.

    2009-11-01

    The 30 to 155 m thick Early Permian (Artinskian) Warchha Sandstone of the Salt Range, Pakistan is a conglomerate, sandstone and claystone succession within which seven lithofacies types (Gt, St, Sp, Sr, Sh, Fl and Fm) occur in a predictable order as repeated fining-upward cycles. Common sedimentary structures in the conglomerates and sandstones include planar and trough cross-bedding, planar lamination, soft sediment-deformed bedding, compound cosets of strata with low-angle inclined bounding surfaces and lags of imbricated pebbles. Structures in the finer-grained facies include desiccation cracks, raindrop imprints, caliche nodules and bioturbation. Groups of associated facies are arranged into nine distinct architectural elements (channels, gravel bars, sandy bedforms, downstream and laterally accreting barforms, sand sheets, crevasse splays, levees, floodplain units and shallow lakes), which is consistent with a fluvial origin for the succession. The types of architectural elements present and their relationship to each other demonstrate that the Warchha Sandstone preserves a record of a meandering river system that drained the northern margin of Gondwanaland. The dominance of fine-grained (floodplain) facies over gravel-grade (channel-base) facies and the widespread occurrence of large-scale lateral accretion elements supports the interpretation of a high-sinuosity, meandering fluvial system in which channel bodies accumulated via the lateral accretion of point bars but in which the active channels covered only a small part of a broad floodplain at any time instant. Although the regional and temporal distribution of these deposits is complex, in broad terms the lower part is dominated by stacked, multistorey channel bodies, whereas single-storey channel elements isolated in abundant fine-grained floodplain deposits dominate the middle and upper parts of the formation.

  19. Assessment of undiscovered sandstone-hosted uranium resources in the Texas Coastal Plain, 2015

    USGS Publications Warehouse

    Mihalasky, Mark J.; Hall, Susan M.; Hammarstrom, Jane M.; Tureck, Kathleen R.; Hannon, Mark T.; Breit, George N.; Zielinski, Robert A.; Elliott, Brent

    2015-12-02

    The U.S. Geological Survey estimated a mean of 220 million pounds of recoverable uranium oxide (U3O8 ) remaining as potential undiscovered resources in southern Texas. This estimate used a geology-based assessment method for Tertiary sandstone-hosted uranium deposits in the Texas Coastal Plain sedimentary strata (fig.1).

  20. Identification of remaining oil resource potential in the Frio Fluvial/Deltaic Sandstone play, South Texas

    SciTech Connect

    Holtz, M.H.; McRae, L.E.; Tyler, N.

    1994-05-01

    The Frio Fluvial/Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas has produced nearly 1 billion stock tank barrels (BSTB) of oil, yet still contains about 1.2 BSTB of unrecovered mobile oil and an even greater amount of residual oil resources (1.5 BSTB). More than half of the reservoirs in this depositionally complex play have been abandoned, and large volumes of oil may remain unproduced. Interwell-scale geological facies models of Frio fluvial/deltaic reservoirs will be combined with engineering assessments and geophysical evaluations in order to characterize Frio fluvial/deltaic reservoir architecture, flow unit boundaries, and the controls that these characteristics exert on the location and volume of unrecovered mobile and residual oil. Reservoir attribute data were statistically analyzed from oil and gas fields throughout the geographic area covered by the Frio Fluvial/Deltaic Sandstone oil play. General reservoir attributes analyzed in detail included porosity, initial water saturation, residual oil saturation, net pay, reservoir area, and fluid characteristics. Statistical analysis of variance demonstrated no difference between oil reservoir attributes and gas reservoir attributes. Probability functions that describe attribute frequency distributions were determined for use in risk adjusting resource calculations. The oil play was found to contain significant volumes of remaining oil. The volumetric probability distribution between 5- and 95-percent probability for original oil in place ranges from 3.8 to 5.6 BSTB, original mobile oil in place ranges from 2.5 to 3.6 BSTB, and residual oil ranges from 1.5 to 2.3 BSTB. The untapped oil resource may be 10 percent of the original oil in place, or 380 million stock tank barrels.

  1. Sedimentology, petrology, and reservoir characteristics of lower Strawn sandstone, Bent Tree field, Hardeman County, Texas

    SciTech Connect

    Moore, T.R.; Bridges, K.F.

    1987-08-01

    Reservoir sandstones of the lower Strawn Formation (early Middle Pennsylvanian) in the Bent Tree field of Hardeman County, Texas, are coarse to fine-grained, texturally submature arkoses. Cores show the sandstones to have been deposited in 1.5-4.5 m thick fining-upward successions of aggraded or prograded bar units. Each bar unit has a sharp erosional base overlain by cross-bedded, coarse-grained, conglomeratic sandstone, which, in turn, is overlain by medium to fine-grained, horizontally bedded or ripple-bedded sandstone. The coarse conglomeratic sandstones are interpreted to represent deposition in main channels of a braided fluvial system that were progressively filled by aggrading and prograding bars. The interbedded, finer grained, more immature sandstones appear to have been deposited in auxiliary channels or swales, or in proximal overbank settings. The detrital framework grain suite of the reservoir sandstones averages 47% quartz, 30% feldspars, 19% igneous rock fragments, and 4% sedimentary rock fragments. The source of these sands was a plutonic/cratonic igneous massif with minor exposures of older sedimentary strata, and was probably the ancestral Wichita Mountains. Diagenesis has significantly affected the petrographic and reservoir properties of the lower Strawn sandstones, primarily through the in-situ alteration of detrital feldspathic grains and by the precipitation of authigenic quartz overgrowths, chlorite clay, and carbonate cements.

  2. Lower Cretaceous barrier reef and outer shelf facies, Sligo Formation, south Texas

    SciTech Connect

    Kirkland, B.L.; Lighty, R.G.; Rezak, R.; Tieh, T.T.

    1987-09-01

    Along the south Texas margin, a vast carbonate-shelf complex with an extensive barrier-reef system and abundant shallow-lagoon and skeletal-shoal deposits existed during the Aptian to Albian. The Sligo Formation represents more than 609.6 m (2000 ft) of deposition along this margin. Facies types along the shelf edge were quantitatively delineated by cluster analysis of detailed point-count data from 90 thin sections of whole cores from five wells. In addition, studies of 42.6 m (140 ft) of core slabs and thin sections of well cuttings from four other wells were used to establish a regional depositional model. Along the Sligo shelf edge, three major facies occur: reef or reef rubble (two subfacies), back reef (three subfacies), and lagoonal (two subfacies). Reef facies are dominated by caprinids and also contain solenoporid algae, stromatoporoids, and an assortment of corals. Behind the reef, a spectrum of extensive back-reef deposits interfinger with shallow (< 5 m), lagoonal sediments. Farther behind the shelf-margin reef complex, along the outer shelf, benthic foraminifera, peloids, and ooids were deposited in high-energy shoals, and are interbedded with low-energy lagoonal sediments. The two types of buildups probably existed along the Sligo shelf margin and the equivalent Cupido shelf margin to the south: (1) wave-resistant coral-caprinid-stromatoporid barrier reefs (adjacent to restricted lagoonal facies), and (2) low-lying rudist banks (adjacent to diverse, washed lagoonal facies).

  3. Upper Permian (Guadalupian) facies and their association with hydrocarbons - Permian basin, west Texas and New Mexico

    SciTech Connect

    Ward, R.F.; Kendall, C.G.S.C.; Harris, P.M.

    1986-03-01

    Outcrops of Guadalupian sedimentary rocks in the Permian basin of west Texas and southeastern New Mexico are a classic example of the facies relationships that span a carbonate shelf. In the subsurface, these rocks form classic hydrocarbon-facies taps. Proceeding from basin to the updip termination of the shelf, the facies are (1) deep-water basin, (2) an apron of allochthonous carbonates, (3) carbonate shelf margin or reef, (4) carbonate sand flats, (5) carbonate barrier islands, (6) lagoon, and (7) coastal playas and supratidal salt flats (sabkhas). Over a half century of exploration drilling has shown that hydrocarbons in the Permian rocks of the Permian basin have accumulated at the updip contact of the lagoonal dolomites and clastics with the coastal evaporites, and in the basinal channel-fill clastics. The shelf marginal (reef) facies contain cavernous porosity, but commonly are water saturated. These facies relationships and hydrocarbon occurrences provide an exploration model with which to explore and rank hydrocarbon potential in other carbonate provinces. 16 figures, 3 tables.

  4. Assessment of tight-gas resources in Canyon sandstones of the Val Verde Basin, Texas, 2016

    USGS Publications Warehouse

    Schenk, Christopher J.; Tennyson, Marilyn E.; Klett, Timothy R.; Mercier, Tracey J.; Brownfield, Michael E.; Gaswirth, Stephanie B.; Hawkins, Sarah J.; Leathers-Miller, Heidi M.; Marra, Kristen R.; Finn, Thomas M.; Pitman, Janet K.

    2016-07-08

    Using a geology-based assessment methodology, the U.S. Geological Survey assessed mean resources of 5 trillion cubic feet of gas and 187 million barrels of natural gas liquids in tight-gas assessment units in the Canyon sandstones of the Val Verde Basin, Texas.

  5. Environment of deposition of downdip Lower Wilcox sandstones, Provident City field, Lavaca County, Texas

    SciTech Connect

    Vest, S.W.

    1990-09-01

    The Lower Wilcox section at Provident City field produces dry gas from thin-bedded, silty sandstones, at depths of 12,500 to 14,100 ft (3,810 to 4,298 m). Cores show that sandstone cosets range 0.1 to 2.7 ft (0.03 to 0.82 m) and average 0.5 8 ft (0. 18 m) in thickness. Sedimentary structures within the cosets range upward from a massive unit (A) to a planar-laminated unit (B) to a ripple-laminated unit (C). The cosets have an average composition of lithic arkose and show textural grading indicative of deposition from turbidity flows. The sandstones lie within the Wilcox fault zone, downdip of the Colorado and Guadalupe deltas of the Rockdale Delta System. Regional stratigraphy and structural trends indicate that the sandstones were deposited in a deep marine environment. A growth fault, having approximately 1000 ft (3048 m) of throw at a depth of 12,300 ft (3750 m), bounds the field to the northwest and largely controls the distribution of lithofacies. Stacked, AB-type, turbidite cosets indicate channel facies. The M Sandstone was deposited as a constructional channel, with abrupt lateral grading to overbank facies, where turbidites of the BC- and C-type are dominant. The S Sandstone was deposited as a series of thin, constructional channels, mostly with turbidites of the AB- and ABC-type that are generally stacked, causing superimposed, dip-trending lobes on an otherwise strike-trending sandstone.

  6. Sedimentary facies and reservoir characteristics of Cretaceous J Sandstone at Torrington field (North), Goshen County, Wyoming, exploration and development implications

    SciTech Connect

    Mikesh, D.L.; Lafollette, R.F.

    1983-08-01

    Torrington field (North) is productive from the Lower Cretaceous J sandstone in the Wyoming portion of the Denver basin. The trapping mechanism is stratigraphic, with reservoir sandstones enveloped laterally and updip by shale-dominated lithofacies. The field has produced 13,000 bbl of oil from two wells since its discovery in late 1981. Three major sedimentary environments and their associated facies, characteristic of a meandered fluvial system, occur within the J interval in the area: abandoned channel, point bar(s), and interfluvial plain. Production at both Torrington (North) and Torrington is from reservoir development within point bar deposits. Cores of the J point bar at Torrington (North) show that it is comprised primarily of very fine to fine-grained quartzarenites and sublitharenites. Sedimentary structures observed in the cores include burrowing and bioturbation, high-angle plane-parallel cross-bedding, discontinuous wavy shale laminae, climbing ripples, and truncated laminae. Although excellent hydrocarbon shows occur from the base to the top of the point bar, production appears to be confined to thin intervals of medium-grained quartzarenite found near the middle of the vertical sequence. Petrophysical reservoir characteristics of the J sandstone were established through examination of X-ray diffraction, scanning electron microscopy, thin-section petrography, and conventional core analysis data. Microporosity development and geometry also affect production. Field extension locations and an exploratory drill site have been established as a result of this study.

  7. Depositional systems and structural controls of Hackberry sandstone reservoirs in southeast Texas

    SciTech Connect

    Ewing, T.E.; Reed, R.S.

    1984-01-01

    Deep-water sandstones of the Oligocene-age Hackberry unit of the Frio Formation contain significant quantities of oil and gas remain potentially one of the most productive exploration targets in southeast Texas. The Hackberry is a wedge of sandstone and shale containing bathyal fauna that separates upper Frio barrier-bar-strandplain sandstones from lower Frio neritic shale and sand. Major Hackberry sandstones lie atop a channeled unconformity that forms the base of the unit. Sandstones in a typical sand-rich channel at Port Arthur field grade upward from a basal, confined channel-fill sandstone to more widespread, broad, fan-channel deposits. Topmost are proximal to medial fan deposits and overbank turbidite deposits. The sequence suggests that Hackberry sandstones were laid down by an onlapping submarine canyon-fan complex deposited in canyons that eroded headward into the contemporaneous Frio barrier system. Regional maps and seismic interpretations outline a network of sand-filled channels extending from the barrier toward the southeast.

  8. Recent Advances in Characterizing Depositional Facies and Pore Network Modeling in Context of Carbon Capture Storage: An Example from the Cambrian Mt. Simon Sandstone in the Illinois Basin

    NASA Astrophysics Data System (ADS)

    Freiburg, J. T.; Nathan, W.; Best, J.; Reesink, A.; Ritzi, R. W., Jr.; Pendleton, J.; Dominic, D. F.; Tudek, J.; Kohanpur, A. H.

    2015-12-01

    In order to understand subsurface flow dynamics, including CO2 plume migration and capillary trapping, a diverse set of geologic properties within the reservoir, from the pore scale to the basin scale, must be understood and quantified. The uncertainty about site-specific geology stems from the inherent variation in rock types, depositional environments, and diagenesis. In collaboration with geocellular and multiphase modeling, detailed characterization of the Lower Mt. Simon Sandstone (LMSS), a reservoir utilized for carbon capture storage, is supporting data-driven conceptual models to better understand reservoir heterogeneity and its relationship to reservoir properties. This includes characterization of sedimentary facies and pore scale modeling of the reservoir The Cambrian-age Lower Mt. Simon Sandstone (LMSS) is a reservoir utilized for two-different carbon capture storage projects in the Illinois Basin, USA. The LMSS is interpreted to have formed in a braided river environment comprising a hierarchy of stratification, with larger scale depositional facies comprising assemblages of smaller scale facies. The proportions, geometries, length scales, and petrophysical attributes of the depositional facies, and of the textural facies they comprise, are being quantified. Based on examination of core and analog outcrop in adjacent areas, the LMSS is comprised of five dominant depositional facies, the most abundant facies being planar to trough cross-bedded sandstones produced by subaqueous sand dunes. This facies has the best reservoir conditions with porosity up to 27% and permeability up to 470 mD. Three-dimensional pore network modeling via micro computed tomography of this facies shows well-connected and unobstructed pore throats and pore space. This presentation will outline the depositional heterogeneity of the LMSS, its relationship to diagenetic fabrics, and its influence on fluid movement within the reservoir.

  9. Depositional setting, structural style, and sandstone distribution in three geopressured geothermal areas, Texas Gulf Coast

    SciTech Connect

    Winker, C.D.; Morton, R.A.; Ewing, T.E.; Garcia, D.D.

    1981-10-01

    Three areas in the Texas Gulf Coast region with different depositional settings, structural styles, and sandstone distribution were studied with well log and seismic data to evaluate some of the controls on subsurface conditions in geopressured aquifers. Structural and stratigraphic interpretations were made primarily on the basis of well log correlations. Seismic data confirm the log interpretations but also are useful in structure mapping at depths below well control.

  10. Lower Permian facies of the Palo Duro Basin, Texas: depositional systems, shelf-margin evolution, paleogeography, and petroleum potential

    SciTech Connect

    Handford, C.R.

    1980-01-01

    A Palo geological study suggests that potential hydrocarbon reservoirs occur in shelf-margin carbonates, delta-front sandstones, and fan-delta arkoses. Zones of porous (greater than 10 percent) dolomite are concentrated near shelf margins and have configurations similar to productive Lower Permian shelf-margin trends in New Mexico. Delta-front sandstones (log-computed porosity of 18 to 25 percent) are similar to producing deltaic sandstones of Morris Buie-Blaco Fields in North-Central Texas. Porous (18 percent) fan-delta sandstones along the south flank of the Amarillo Uplift may form reservoirs similiar to that of the Mobeetie Field on the north side of the Amarillo Uplife in Wheeler County, Texas. Potential hydrocarbon source beds occur in slope and basinal environments. Total organic carbon generally ranges from 1 to 2.3 percent by weight and averages 0.589 percent by weight.

  11. Facies and diagenesis of Goen Limestone cyclothem (early late Desmoinesian), Concho and Runnels Counties, central Texas

    SciTech Connect

    Marquis, S.A. Jr.

    1988-02-01

    The Goen Limestone (early late Desmoinesian) of Concho and Runnels Counties, central Texas, consists of three vertically stacked transgressive-regressive sequences, each cycle beginning with a thin clay-rich transgressive unit which passes upward into thick regressive limestones. The major porosity-forming process in the Goen Limestone was early leaching as a result of meteoric-phreatic lenses which migrated primarily in response to glacio-eustatic sea level changes. The dominant porosity-reducing processes included early cementation by equant nonferroan spar in a meteoric-phreatic environment and late stage saddle dolomitization in a deeper burial connate environment. Bladed high-Mg calcite, silica, equant ferroan spar, and anhydrite cements resulted in minor porosity occlusion. The hydrocarbon-producing regressive units (foraminiferal and bryozoan-rugose coral facies) underwent the most complex diagenetic histories and contain extensive secondary pores (algal molds, vugs, micropores, and open stylolitic pores), which contrasts sharply with the unleached, nonporous transgressive facies. The presence or absence of glacio-eustatically controlled, penetrating freshwater lenses, the distribution of green phylloid algae, and the extent of secondary pore-filling cementation were the major factors controlling reservoir capability of Goen facies.

  12. Petrography and diagenesis of Eagle Mills sandstones, subsurface - Northeast Texas and southwest Arkansas

    SciTech Connect

    Dawson, W.C.; Callender, C.A. )

    1991-03-01

    The Eagle Mills Formation (Triassic-Jurassic) has been penetrated by several deep wells (12,000 to 18,000 ft) in northeast Texas and southwest Arkansas. It consists of green, red, and pink conglomeratic lithic arenites and fine- to coarse-grained feldspathic arenites, interbedded with red and greenish gray shales and siltstones. Lithic arenites contain basalt, chert, quartzite, and dolomite rock fragments; plagioclase is the predominant feldspar. All Eagle Mills sandstones have low textural and mineralogic maturities. Eagle Mills red beds and associated intrusive igneous rocks (diabase and basalt dikes and sills) represent the fillings of grabens or rift basins that actively subsided during deposition (in alluvial, fluvial-deltaic, and lacustrine paleoenvironments). Eagle Mills lithic and feldspathic sandstones have undergone a complex diagenetic history, including chlorite cementation (pore linings and pore fillings), compaction, quartz and feldspar overgrowths, dolomite cementation, chloritization and albitization of detrital feldspars, local dissolution of framework grains (igneous lithics and feldspars), precipitation of kaolinite, late Fe-calcite cementation, and saddle dolomite formation. Cement mineralogies are strongly correlative with lithofacies. Lithic sandstones contain the highest frequency of chlorite cements, whereas feldspathic sandstones are preferentially cemented with carbonates and anhydrite; quartz and feldspar overgrowths are ubiquitous. The suite of authigenic minerals in Eagle Mills sandstones records progressive burial into a deep, high-temperature (120-150C), semiclosed, diagenetic regime.

  13. Seismic modeling, rock physics, avo and seismic attribute analysis for illuminating sandstone facies of the Late Ordovic Ian Mamuniyat Reservoir, R-Field, Murzuq Basin-Libya

    NASA Astrophysics Data System (ADS)

    Abushalah, Yousf Milad

    The Late Ordovician Mamuniyat Formation is the main hydrocarbon reservoir in the R-Field in Murzuq Basin, SW Libya. The Lower Mamuniyat, which is the only unit that was encountered in the study area, is composed of sandstone facies called Clean Mamuniyat and shaly sandstone facies called Dirty Mamuniyat. One major problem with the development of the R-Field is the difficulty of distinguishing the two units so this project was aimed to develop better methods for distinguishing between the two units of the Lower Mamuniyat. The other problem is to distinguish the transgressive shaly facies of the Bir Tlacsin, which has an impact on the hydrocarbon accumulation. Those issues manifested in limit of seismic resolution and interference that resulted from the converted shear mode waves. The dissertation was divided into three chapters. In the first chapter, seismic modeling using a deterministic and a Ricker wavelet were used to investigate the interference effects on the poststack seismic data and a bandpass filter was used to remove those effects. Instantaneous frequency, spectral-based colored inversion and rock physics were, then applied to determine the distributions of the sandstone facies of the Lower Mamuniyat Formation and to interpret the depositional setting of it. In the second chapter, spectral decomposition and inverted density were utilized to determine the distribution of the shaly facies of Bir Tlacsin, and its temporal thickness and to remap the top reservoir. In the last chapter, amplitude variation with offset (AVO) modeling, ray tracing, and spectral analysis were used to investigate the mode conversion and its effect on AVO signature, the amplitude of the near-mid and far offsets and frequency contents. Data enhancement then was performed using partial stacks and a bandpass filter.

  14. Mineralogy and geochemistry of the main glauconite bed in the Middle Eocene of Texas: paleoenvironmental implications for the verdine facies.

    PubMed

    Harding, Sherie C; Nash, Barbara P; Petersen, Erich U; Ekdale, A A; Bradbury, Christopher D; Dyar, M Darby

    2014-01-01

    The Main Glauconite Bed (MGB) is a pelleted greensand located at Stone City Bluff on the south bank of the Brazos River in Burleson County, Texas. It was deposited during the Middle Eocene regional transgression on the Texas Gulf Coastal Plain. Stratigraphically it lies in the upper Stone City Member, Crockett Formation, Claiborne Group. Its mineralogy and geochemistry were examined in detail, and verdine facies minerals, predominantly odinite, were identified. Few glauconitic minerals were found in the green pelleted sediments of the MGB. Without detailed mineralogical work, glaucony facies minerals and verdine facies minerals are easily mistaken for one another. Their distinction has value in assessing paleoenvironments. In this study, several analytical techniques were employed to assess the mineralogy. X-ray diffraction of oriented and un-oriented clay samples indicated a clay mixture dominated by 7 and 14Å diffraction peaks. Unit cell calculations from XRD data for MGB pellets match the odinite-1M data base. Electron microprobe analyses (EMPA) from the average of 31 data points from clay pellets accompanied with Mössbauer analyses were used to calculate the structural formula which is that of odinite: Fe(3+) 0.89 Mg0.45 Al0.67 Fe(2+) 0.30 Ti0.01 Mn0.01) Σ = 2.33 (Si1.77 Al0.23) O5.00 (OH)4.00. QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) data provided mineral maps of quantitative proportions of the constituent clays. The verdine facies is a clay mineral facies associated with shallow marine shelf and lagoonal environments at tropical latitudes with iron influx from nearby runoff. Its depositional environment is well documented in modern nearshore locations. Recognition of verdine facies clays as the dominant constituent of the MGB clay pellets, rather than glaucony facies clays, allows for a more precise assessment of paleoenvironmental conditions.

  15. Mineralogy and Geochemistry of the Main Glauconite Bed in the Middle Eocene of Texas: Paleoenvironmental Implications for the Verdine Facies

    PubMed Central

    Harding, Sherie C.; Nash, Barbara P.; Petersen, Erich U.; Ekdale, A. A.; Bradbury, Christopher D.; Dyar, M. Darby

    2014-01-01

    The Main Glauconite Bed (MGB) is a pelleted greensand located at Stone City Bluff on the south bank of the Brazos River in Burleson County, Texas. It was deposited during the Middle Eocene regional transgression on the Texas Gulf Coastal Plain. Stratigraphically it lies in the upper Stone City Member, Crockett Formation, Claiborne Group. Its mineralogy and geochemistry were examined in detail, and verdine facies minerals, predominantly odinite, were identified. Few glauconitic minerals were found in the green pelleted sediments of the MGB. Without detailed mineralogical work, glaucony facies minerals and verdine facies minerals are easily mistaken for one another. Their distinction has value in assessing paleoenvironments. In this study, several analytical techniques were employed to assess the mineralogy. X-ray diffraction of oriented and un-oriented clay samples indicated a clay mixture dominated by 7 and 14Å diffraction peaks. Unit cell calculations from XRD data for MGB pellets match the odinite-1M data base. Electron microprobe analyses (EMPA) from the average of 31 data points from clay pellets accompanied with Mössbauer analyses were used to calculate the structural formula which is that of odinite: Fe3+0.89 Mg0.45 Al0.67 Fe2+0.30 Ti0.01 Mn0.01) Σ = 2.33 (Si1.77 Al0.23) O5.00 (OH)4.00. QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) data provided mineral maps of quantitative proportions of the constituent clays. The verdine facies is a clay mineral facies associated with shallow marine shelf and lagoonal environments at tropical latitudes with iron influx from nearby runoff. Its depositional environment is well documented in modern nearshore locations. Recognition of verdine facies clays as the dominant constituent of the MGB clay pellets, rather than glaucony facies clays, allows for a more precise assessment of paleoenvironmental conditions. PMID:24503875

  16. Clay mineralogy and its controls on production, Pennsylvanian upper Morrow sandstone, Farnsworth field, Ochiltree County, Texas

    SciTech Connect

    Munson, T.W. )

    1989-12-01

    Farnsworth field in Ochiltree County, Texas, is the most prolific upper Morrow oil field in the Anadarko basin, producing more than 36 million bbl of oil and 27 billion ft{sup 3} of gas since its discovery in 1955. The bulk of the production comes from an upper Morrow-aged sandstone locally referred to as the Buckhaults sandstone. The Buckhaults sandstone is a coarse to very coarse-grained, arkose to arkosic wacke. Grain-size distributions, sedimentary structure analysis, and sand-body geometry indicate that the Buckhaults was deposited in a fluvial-deltaic environment as distributary channel and distributary mouth-bar sands. Depositional strike is northwest to southeast. The source area for the Buckhaults sediments was primarily a plutonic igneous terrane, with a minor contribution from volcanic and reworked sedimentary rocks. The proposed source area is the Amarillo-Wichita uplift to the south. In addition, the Cimarron arch and/or Keyes dome to the west-northwest may also have contributed sediment to the study area. The large (average) grain size, the amount of feldspar present, and the overall immaturity of the Buckhaults sediments indicate a relatively short distance of transport. Detailed scanning electron microscopy and x-ray diffraction analysis of cores from the productive interval coupled with comparisons of varying completion practices across the field indicate a significant correlation between individual well performance, clay mineralogy, and completion technique.

  17. Van Horn Sandstone, Trans-Pecos Texas: Evidence for Late Cambrian rifting along southern North America

    SciTech Connect

    Hongshuan, Ye; Soegaard, K. . Programs in Geosciences)

    1993-02-01

    The Van Horn Sandstone in the Trans-Pecos region of west Texas is interpreted as a rift sequence which developed in response to Cambrian breakup along the southern margin of the North American continent. The Van Horn Sandstone consists exclusively of braided alluvial sediments and occupies relatively small isolated basins in the vicinity of the town of Van Horn. The sandstone is in structural unconformable contact above intensely deformed Precambrian sediments which are < 1,123 Ma old. The Van Horn Sandstone is overlain by more than 650 meters of earliest Ordovician to Mississippian shallow-marine shelf sediments. Geohistory analysis of the overlying Paleozoic shelf sediments indicates that subsidence was driven by thermal contraction of the crust and that the shallow-marine sediments represent a drift sequence. Subsidence history curves correspond with theoretical thermal decay curves where [beta] = 1.2 and suggest that thermal subsidence commenced in Late Cambrian time about 510 Ma ago. Increased crustal attenuation, resulting in development of an ocean basin, occurred between Van Horn and the original location of deep water sediments presently exposed in the Marathon uplift to the south. Proposed Late Cambrian breakup south of Van Horn is coeval with rifting in the southern Oklahoma aulachogen and Rome trough in the Appalachian Mountains, but post-dates the main Late Proterozoic rifting event between 625 and 555 Ma along the eastern and western freeboard of North American. The significance of diachronous rifting in Eocambrian-Cambrian time is unclear at present but has consequences for fragmentation of the late Precambrian supercontinent Rodinia'.

  18. Depositional environments and hydrocarbon occurrence of upper Jurassic Cotton Valley sandstones, Mississippi, Louisiana, and Texas

    SciTech Connect

    Kornfeld, I.

    1985-02-01

    The sandstones of the Kimmeridgian (Jurassic) upper Cotton Valley Formation of Mississippi, northern Louisiana, and eastern Texas were deposited on a stable subsiding shelf. These sands are regressive and are part of a complex of deltaic and marine systems. They are quartz-rich and exhibit a variety of sedimentary structures. Cotton Valley fluvial-deltaic systems drained Paleozoic and younger highlands to the north and northwest, depositing sands on the shelf where they were subsequently reworked. Three depositional environments have been interpreted for these sands in Mississippi: (1) a constructive delta in the west-central part of the state, (2) a destructive delta in the east-central part of the state, and (3) an interdeltaic system in central Mississippi between the other systems. In northern Louisiana and northeastern Texas, the following environments have been interpreted: a proximal destructive delta system in northwest Louisiana and northeast Texas and another delta system in northeastern Louisiana with an interdeltaic system consisting of barrier beaches and barrier bars located centrally between them. Production is controlled by porosity and permeability barriers, fault traps, and salt- and basement-induced structures.

  19. Facies and geochemical characterization of Mississippian rocks in Palo Duro and Hardeman basins, Texas

    SciTech Connect

    Ruppel, S.c.

    1985-02-01

    Mississippian rocks in the southern Texas Panhandle constitute a complex sequence of carbonate deposits formed in a platform-to-basin setting. Following relatively rapid transgression and inundation of the area from the north and east, the Hardeman basin area was characterized by outer platform conditions in which isolated carbonates buildups developed surrounded by relatively deep water. The Palo Duro basin to the west was the site of shallow-water, inner platform deposition. In intermediate areas, limestone turbidites, perhaps derived from carbonate buildups to the east, accumulated in quiet water. After this initial transgression, an upward shallowing trend resulted in the formation of ooid to skeletal shoals throughout the area. Although current production in the area is coincident with the distribution of organic-rich Upper Mississippian shales in the eastern part of the Hardeman basin, TOC studies indicate that potential carbonate source rocks are present in the western Hardeman and eastern Palo Duro basins. Mississippian rocks in the Palo Duro basin proper have little source rock potential. Vitrinite reflectance studies indicate that Hardeman basin rocks are well within the oil window. However, correlative deposits at equivalent depths in most of the Palo Duro basin are only marginally mature. Although thermal maturity seems to be mirrored by the presence geothermal gradient, and source rock quality appears related to depositional setting (depth of water), successful exploration outside currently productive areas will require a detailed analysis of organic geochemistry and depositional facies.

  20. Carbonate facies and stratigraphic framework of middle Magdalena (middle Pennsylvanian), Hueco Mountains, west Texas

    SciTech Connect

    Lambert, L.L.; Stanton, R.J. Jr.

    1988-01-01

    The middle Magdalena of the Hueco Mountains, west Texas, is best exposed in the vicinity of Pow Wow Canyon, particularly along the western scarp of the range. It can be divided into two major depositional sequences, the lowermost of which consists predominantly of alternating bank, interbank, and shoal deposits of Atokan age. These banks are low-relief accumulations of Donezella, with coeval slackwater skeletal wackestones and interbedded deposits of foraminiferal sands. A prominent zone of intertonguing Chaetetes biostromes punctuates the middle part of this sequence. The Desmoinesian sequence begins as a series of rubbly limestones in association with abundant silicified plant remains and is interpreted as a set of paleosols. These are overlain by argillaceous, low-diversity wackestones and packstones of lagoonal origin, followed by carbonates of more open-marine circulation with abundant corals and other stenotypic fossils. In turn, these deposits are succeeded by a sequence of phylloid algal banks that increase in resistance upward to where they represent strata of the upper Magdalena. At this locality, however, the upper Magdalena is very thin because it is truncated by the pre-Hueco unconformity which, so prominent at the head of the canyon, can now be traced to the western scarp. These deposits are directly analogous to subsurface reservoir facies of the same age on the opposite side of the Diablo uplift in the Permian basin and thus provide an opportunity to generate reservoir models based on extensive outcrop exposure.

  1. Depositional setting, structural style, and sandstone distribution in three geopressured geothermal areas, Texas Gulf Coast

    SciTech Connect

    Winker, C.D.; Morton, R.A.; Ewing, T.E.; Garcia, D.D.

    1983-01-01

    Three areas in the Texas Gulf Coastal Plain were studied using electric logs and seismic-reflection data to interpret their depositional and structural history and to compare their potential as geopressured-geothermal reservoirs. The Cuero study area, on the lower Wilcox (upper Paleocene) growth-fault trend, is characterized by closely and evenly spaced, subparallel, down-to-the-basin growth faults, relatively small expansion ratios, and minor block rotation. Distributary-channel sandstones in the geopressured lower Wilcox Group of the South Cook fault block appear to be the best geothermal aquifers in the Cuero area. The Blessing study area, on the lower Frio (Oligocene) growth-fault trend, shows wider and more variable fault spacing and much greater expansion ratios and block rotation, particularly during early Frio time. Thick geopressured sandstone aquifers are laterally more extensive in the Blessing area than in the Cuero area. The Pleasant Bayou study area, like the Blessing area, is on the Frio growth-fault trand, and its early structural development was similar rapid movement of widely spaced faults resulted in large expansion ratios and major block rotation. However, a late-stage pattern of salt uplift and withdrawal complicated the structural style. Thick geopressured lower Frio sandstone aquifers are highly permeable and laterally extensive, as in the Blessing area. In all three areas, geopressured aquifers were created where early, rapid movement along down-to-the-basin growth faults juxtaposed shallow-water sands against older shales, probably deposited in slope environments. Major transgressions followed the deposition of reservoir sands and probably also influenced the hydraulic isolation that allowed the build up of abnormal pressures. 26 refs., 49 figs., 8 tabs.

  2. Exploration potential and variations in shelf plume sandstones, Navarro group (Maestrichtian), east-central Texas

    SciTech Connect

    Patterson, J.E. Jr.; Scott, A.J.

    1984-04-01

    Fine-grained marine sandstones within the Kemp Clay of the Navarro Group (Maestrichtian) of east-central Texas were deposited on a muddy, shallow shelf by migrating sandbars. These sands were transported in traction from deltaic headlands by seaward-deflected coastal/shelf currents. The sand formed thin (3-20 ft; 1-6 m) arcuate belts (shelf sand plumes) which were 17-20 mi (27-32 km) wide and extended 27-30 mi (43-48 km) downdrift and 21-40 mi (34-64 km) onto the shelf. Orientation of the long axes of ridges, formed by the stacking of individual bars within the shelf sand plume, changes (from dip to strike-oriented downdrift) corresponding to the flow directions of the shelf currents. Southwestward, fair-weather reworking of these delta-supplied sands by shelf currents resulted in the down-current stratigraphic climbing of the migrating shelf-bar complexes. Onshore stratigraphic climbing in the landward parts of the plume complexes was related to storm activity. Current patterns and the resulting distribution of sand were influenced by the configuration of the shelf and the topographic relief inherited from previously deposited deltaic/shelf depositional platforms. Three variations of the basic shelf sandstone-plume model were recognized in the study area: (1) a rapidly deposited, immature plume, (2) an abandoned, current-reworked plume, and (3) a storm-modified, onshore-reworked plume. Each of these variants displays unique characteristics which influence their potential as hydrocarbon reservoirs.

  3. Elemental mobility in sandstones during burial: Whole-rock chemical and isotopic data, Frio Formation, south Texas

    SciTech Connect

    Milliken, K.L.; Mack, L.E.; Land, L.S. . Dept. of Geological Sciences)

    1994-10-03

    The deepest (> 3.5 km) and most altered Oligocene Frio sandstones from south Texas typically contain authigenic minerals that exceed 30 volume percent of the rock. Elemental and isotopic analyses of whole rocks confirm conclusions based on petrography that authigenesis is accompanied by substantial material transfer involving both import to and export from the sandstone. Material transfer on the scale observed demonstrates that burial diagenesis is an open-system process for several major elements, and introduces a major obstacle to use of elemental data for provenance interpretation. Defining the sources of materials transported into sandstones, and the fate of materials exported, is key to documenting the scale of system closure in sedimentary basins and requires a better understanding of diagenetic processes in mudrocks.

  4. Geology and recognition criteria for sandstone uranium deposits in mixed fluvial-shallow marine sedimentary sequences, South Texas. Final report

    SciTech Connect

    Adams, S.S.; Smith, R.B.

    1981-01-01

    Uranium deposits in the South Texas Uranium Region are classical roll-type deposits that formed at the margin of tongues of altered sandstone by the encroachment of oxidizing, uraniferous solutions into reduced aquifers containing pyrite and, in a few cases, carbonaceous plant material. Many of the uranium deposits in South Texas are dissimilar from the roll fronts of the Wyoming basins. The host sands for many of the deposits contain essentially no carbonaceous plant material, only abundant disseminated pyrite. Many of the deposits do not occur at the margin of altered (ferric oxide-bearing) sandstone tongues but rather occur entirely within reduced, pyurite-bearing sandstone. The abundance of pyrite within the sands probably reflects the introduction of H/sub 2/S up along faults from hydrocarbon accumulations at depth. Such introductions before ore formation prepared the sands for roll-front development, whereas post-ore introductions produced re-reduction of portions of the altered tongue, leaving the deposit suspended in reduced sandstone. Evidence from three deposits suggests that ore formation was not accompanied by the introduction of significant amounts of H/sub 2/S.

  5. Fluvial and deltaic facies and environments of the late permian back-reef shelves of the Permian Basin of Texas and New Mexico

    SciTech Connect

    Mazzullo, J. )

    1993-02-01

    The Artesia Group is a sequence of carbonates, evaporites, and clastics that was deposited across the back-reef shelves of the Permian Basin during late Permian time. There has been some controversy over the depositional environments of the clastic members of the Artesia Group and the role of sea level fluctuations in their accumulation. However, the results of a regional core study of the Queen Formation of the Artesia Group indicate that they were largely deposited in desert fluvial and deltaic environments during low-stands of sea level. Three fluvial-deltaic facies are recognized within the clastic members of the Queen. The first consists of medium to very find sandstones and silty sandstones with cross-beds, ripple cross-laminae, and planar and wavy laminae. This facies forms wavy sheets that thicken and thin along linear trends, and was deposited in sandy braided streams. The second facies consists of very find to fine sandstones, silty sandstones, and siltstones with ripple cross-laminae, planar and wavy laminae, cross-beds, clay drapes and pedogenetic cutans, as well as siltstones and silty mudstones with haloturbation structures and evaporite nodules. This facies forms thick planar sheets, and was deposited in fluvial sandflats and adjacent fluvial-dominated continental sabkhas. The third facies consists of cyclic deposits of haloturbated silty mudstones that grade into siltstones and very fine sandstones with crossbeds, planar and wavy laminae, haloturbation structures and evaporite nodules. Each cycle forms a lobate body that is bounded by carbonates or evaporites and which was deposited in sheet deltas that formed along the landward margins of a back-reef lagoon.

  6. Secondary natural gas recovery in mature fluvial sandstone reservoirs, Frio Formation, Agua Dulce Field, South Texas

    SciTech Connect

    Ambrose, W.A.; Levey, R.A. ); Vidal, J.M. ); Sippel, M.A. ); Ballard, J.R. ); Coover, D.M. Jr. ); Bloxsom, W.E. )

    1993-09-01

    An approach that integrates detailed geologic, engineering, and petrophysical analyses combined with improved well-log analytical techniques can be used by independent oil and gas companies of successful infield exploration in mature Gulf Coast fields that larger companies may consider uneconomic. In a secondary gas recovery project conducted by the Bureau of Economic Geology and funded by the Gas Research Institute and the U.S. Department of Energy, a potential incremental natural gas resource of 7.7 bcf, of which 4.0 bcf may be technically recoverable, was identified in a 490-ac lease in Agua Dulce field. Five wells in this lease had previously produced 13.7 bcf from Frio reservoirs at depths of 4600-6200 ft. The pay zones occur in heterogeneous fluvial sandstones offset by faults associated with the Vicksburg fault zone. The compartments may each contain up to 1.0 bcf of gas resources with estimates based on previous completions and the recent infield drilling experience of Pintas Creek Oil Company. Uncontacted gas resources occur in thin (typically less than 10 ft) bypassed zones that can be identified through a computed log evaluation that integrates open-hole logs, wireline pressure tests, fluid samples, and cores. At Agua Dulce field, such analysis identified at 4-ft bypassed zone uphole from previously produced reservoirs. This reservoir contained original reservoir pressure and flowed at rates exceeding 1 mmcf/d. The expected ultimate recovery is 0.4 bcf. Methodologies developed in the evaluation of Agua Dulce field can be successfully applied to other mature gas fields in the south Texas Gulf Coast. For example, Stratton and McFaddin are two fields in which the secondary gas recovery project has demonstrated the existence of thin, potentially bypassed zones that can yield significant incremental gas resources, extending the economic life of these fields.

  7. San Andres dolomite reservoir, Emma field, Andrews County, Texas: Depositional facies and diagenesis

    SciTech Connect

    Ruppel, S.C. )

    1987-02-01

    Although nearly 100% (19 million bbl of oil) of the estimated recoverable oil in the Emma San Andres reservoir has been produced, indications are that as much as 15 million bbl of recoverable, movable oil remains. Detailed study of facies and diagenesis in the reservoir reveals considerable lateral and vertical variability, which has important implications for recovery and injection efficiencies in the field. The upper San Andres Formation in the Emma field comprises a shallowing-upward sequence of pervasively dolomitized, shallow-water subtidal to supratidal carbonates that accumulated on a gently east-sloping ramp. The lowermost part of the reservoir interval is composed of laterally extensive fusulinid packstone deposited in an open-marine ramp setting. Abruptly overlying this facies is a sequence of interbedded fusulinid/algal grainstone, formed in a migrating sand-shoal complex, and burrowed, skeletal mudstone deposited on a restricted inner ramp. The grainstone is restricted to the western and central parts of the field. These deposits are overlain by pisolitic and cryptalgal mudstones and terrigenous siliciclastics of supratidal origin. Anydrite is abundant throughout the section. Porosity and permeability are facies controlled. Highest permeabilities are developed in shoal complex grainstone (100 md) and in fusulinid packstone (925-50 md). Lateral and vertical facies variations resulted in considerable reservoir heterogeneity. Trace-element and isotope data indicate that most of the San Andres dolomite and associated sulfate (anhydrite) precipitated from downward-moving, seawater-derived brines during shallow burial in the late Guadalupian. Subsequent anhydrite dissolution has locally enhanced original porosity.

  8. Evaluation of evaporite facies as a tool for exploration, Yates Field, Texas

    SciTech Connect

    Spencer, A.W.; Warren, J.K.

    1987-05-01

    Evaporites have long been recognized as the most efficient reservoir seal; however, the seal can itself serve as an exploration tool to locate subtle stratigraphic traps. By analogy with modern environments, thick massive evaporites form subaqueously in ponds (salinas) in topographic lows while sabkhas form on the subaerially exposed supratidal zone on topographic highs. Recognition of evaporite facies distribution can delineate paleotopography where sabkhas form a seal over local highs and closure is provided by salinas forming a lateral seal in lows. These relationships are illustrated by the giant Yates field (2 billion bbl reserves), situated at the southern tip of the Central basin platform in the Permian basin. The seal over the Yates reservoir (San Andres formation) is formed by the evaporites at the base of the Seven Rivers Formation (Guadalupian). Within the evaporite, two distinct depositional facies are recognized: a massive, salina-anhydrite in the central and western parts of the field; and on the east, stacked sabkha sequences consisting of sandy dolomite overlying a sharp base, grading into nodular anhydrite and capped by an erosional surface. The depositional topography on the underlying San Andres reservoir controlled the facies distribution in the basal Seven Rivers. Carbonate buildups formed on the eastern side of the field, while interbedded shales and dolomites accumulated in the quiet lagoonal waters behind. Due to dewatering and compaction during early burial, the lagoons remained topographically low until early Seven Rivers time when they were finally filled with salina evaporites. The rigid shelf margin buildups remained as topographic highs over which sabkhas developed. Only 10% of the production has come from the lagoonal muds under the salinas, while 90% has been produced from the carbonate buildups under the sabkhas.

  9. Coal zone stratigraphy - A new tool for high-resolution depositional sequence stratigraphy in near-marine to non-marine fluvial-deltaic facies associations: A case study from the Ferron Sandstone, East-Central Utah

    SciTech Connect

    Garrison, J.R. Jr.; Van Den Bergh, T.C.V.

    1996-06-01

    A detailed 3 km strike cross-section in Willow Springs Wash and an intersecting 22 km dip cross-section from north of Last Chance Creek to north of Ivie Creek have delineated seven parasequence sets within the Ferron Sandstone near-marine to non-marine system. Nine near-marine parasequences have been identified within Parasequence Set 1 and three within Parasequence Set 2. In the study area, Parasequence Sets 3-7 are represented by delta plain facies associations. Parasequence sets are capped by laterally extensive coal zones consisting of beds of coal and correlative carbonaceous shales, altered volcanic ash layers (tonsteins), rooted zones, organic-rich mudstones/siltstones, and crevasse deposits. The preservation of tonstein decreases with distance from the paleo-shoreline. These time transgressive coal zones are thickest near landward pinchouts of the older delta front sandstones within the set. They frequently split into multiple zones. Delta front sandstones of the more landward parasequences are frequently incised by distributary channels. With time, these channels are abandoned and filled with sandstones, thinly bedded heterolithics, or transgressive deposits; subsequently, peat accumulation begins. The seaward-stepping parasequence sets contain a large number of seaward-stepping parasequences, capped by a thin transgressive delta-plain facies association. The youngest parasequences may be embedded within splits in the coal zone, and may occur landward relative to older, underlying parasequences. Ferron Sandstone parasequence sets are punctuated by development of extensive peat accumulations and their correlative facies associations, which are preserved as coal zones.

  10. Stratigraphic hierarchy of organic carbon rich siltstones in deep-water facies, Brushy Canyon Formation (Guadalupian), Delaware Basin, West Texas

    NASA Astrophysics Data System (ADS)

    Sageman, Bradley B.; Gardner, Michael H.; Armentrout, John M.; Murphy, Adam E.

    1998-05-01

    The first systematic test for a predictive relationship between organic carbon content and stratigraphic hierarchy in a deep-water slope to basin-floor deposit was performed. The studied section includes the Pipeline Shale, the Brushy Canyon Formation, and the lower part of the Cherry Canyon Formation of the Delaware Mountain Group, West Texas. This interval represents one large-scale, 3rd-order genetic sequence within which 4th- and 5th-order stratigraphic cycles are recognized. Samples of fine-grained facies throughout the section were collected from outcrop and analyzed for organic carbon content and hydrogen index. Degree of pyritization was also determined for a subset of the samples. The results indicate that organic enrichment is closely correlated to the stratigraphic hierarchy at the 3rd-, 4th-, and 5th-order levels. The data suggest that quantity and quality of preserved organic matter are controlled by changes in bulk sedimentation rate (dilution vs. condensation), which affect organic matter inputs to the sediment, as well as the balance between (1) burial and preservation of organic matter and (2) its degradation on the sea floor during times of sediment starvation.

  11. Contrasting evolutionary patterns of Lower Permian shelf and basinal facies, Midland basin, Texas

    SciTech Connect

    Mazzullo, S.J.; Reid, A.M.

    1987-05-01

    The evolution of carbonate and siliciclastic shelf-to-basin depositional systems of the Lower Permian in the Midland basin was influenced by eustatic fluctuations, changing shelf-margin biota, and concurrent tectonism. The development of these systems from Wolfcampian to Leonardian time (28-m.y. duration) involved seven distinct phases that are recognized seismically as third and lesser order cycles. These phases are (1) highstand progradational shelf carbonate packages, separated by low-stand deltaic and basinal shales, deposited during relatively long-term eustatic cycles (early Wolfcampian); the component carbonate systems evolved from ramps to distally steepened ramps associated with nonframe-building algal reefs and grainstones, with little resedimented foreshelf detritus; (2) dominantly carbonate deposition during the middle and early late Wolfcampian, with construction of offlapping (but laterally juxtaposed) progradational shelves with steep platform margins deposited during a lengthy period of stillstand and/or slow submergence; dolomitized platform-margin facies are composed of marine-cemented, sponge-algal reefs and grainstones, with resedimented carbonate megabreccia to micrite channels and lobes in the contiguous shale basin; (3) shelf emergence and erosion during a major late middle(.) to late Wolfcampian lowstand contemporaneous with basinwide tectonism, with mass wastage into the basin of the terminal Wolfcampian platform-margin carbonate section; (4) regional transgression and black shale deposition followed by a repeat of Phase 2 type systems in the latest Wolfcampian to earliest Leonardian but under arid conditions; rapid vertical platform margin accretion by dolomitized, marine-cemented, sponge-algal-coral reefs and grainstones, and deposition of thick foreshelf megabreccia wedges, aprons, channels, and lobes;

  12. Smackover and Haynesville facies relationships in north-central East Texas

    SciTech Connect

    Stewart, S.K.

    1984-09-01

    The Smackover Formation was deposited as a coarsening-upward carbonate unit that developed first with the deposition of transgressive laminated silty limestones in deep anoxic waters. Mudstones and wackestones were deposited during a slow rise in sea level as the carbonate system became established. Packstones and grainstones were deposited at the Smackover shelf margin in thick coarsening-upward sequences. Local lenses of anhydrite and dolomitic mud developed on the shoreward side of the shelf break. Pelleted sands also developed in the low-energy Smackover lagoon. Ultimately, a thin blanket of ooid sands covered the shelf. During Haynesville deposition, a carbonate barrier at the shelf margin created an evaporative lagoon in which Buckner anhydrite and halite precipitated. As sea level rose, limestones and dolomites were deposited along the downdip margin of the Buckner lagoon. Terrigenous clastics began to prograde into the updip areas. Continued sea level rise flooded the shelf, and Gilmer limestones were deposited as far updip as the present Mexia-Talco fault zone. At the end of Haynesville depositions, limestones and shales were deposited on either side of the Gilmer shelf margin as quartzose clastics continued to prograde into updip areas. Evidence in east Texas suggests that the depositional model for the Smackover followed a shelf margin rather than the generally accepted ramp model. The shelf margin is clearly identified as a carbonate barrier during Haynesville deposition, outlining a Buckner lagoon as the depocenter that continued to subside at least through the end of Haynesville deposition.

  13. Relationships of Bexar shale, Hensel sandstone, and Hensel dolomite (basal upper Trinity, Comanchean Cretaceous) in south-central Texas

    SciTech Connect

    Amsbury, D.L.

    1984-04-01

    The Bexar Shale has been considered the offshore equivalent of the Cow Creek Limestone, the overlying Hensel sandstone, or of the disconformity between them in outcropping sections. Cores and outcrops in Comal, Kendall, and northern Bexar Counties preserve calcitic and dolomitic caliche in the top of the Cow Creek Limestone. Above the caliche is 8-16 m(25-50 ft) of laminated or bioturbated, dolomitic siltstone and silty dolomite (Hensel dolomite). Dolomite is euhedral and silt-sized. The lower part contains collophane grains and oyster shells replaced partly by chalcedony. Carbonate grains within the upper part include angular and well-rounded mollusk and echinoid fragments; many are pyritic and coated by glauconite. Terrigenous grains in Hensel dolomite grade upward from silt to coarse subarkose sand from central Texas. In southern Bexar County, about 35 m (115 ft) of silt-, clay-, and calcite-mudstone referable to the Bexar Shale sharply overlie shallow marine Cow Creek Limestone, and grade abruptly upward into about 7 m (23 ft) of Hensel dolomite. Dolomite is overlain by calcarenite of the Glen Rose Formation containing subarkose sand grains. Similar distinctive sand grains occur in well cuttings of basal Glen Rose beds northeastward through Travis County. The Bexar represents a flood of clay-sized sediment from a distant source, spread across the San Marcos arch during a rapid transgression. Slightly younger sand, silt, and local clay of the Hensel sandstone were eroded from central Texas by a few flash floods during a major period of caliche formation in the area.

  14. Failure studies on Texas Gulf Coast geopressured-geothermal sandstones and shales

    SciTech Connect

    Jogi, P.N.; Llewellyn, B.C.; Gray, K.E.

    1981-10-01

    Triaxial compression tests were run at room temperature to determine failure characteristics of rocks extracted from the geopressured-geothermal reservoir underlying Brazoria County. Effects of both confining and pore fluid pressure were considered. Like all other rocks, ultimate strength was found to increase with increase in effective confining pressure. Partial ductile behavior was observed at pressures above 5000 psi. In general rocks from this reservoir were found to be considerably weaker than corresponding well compacted sandstones.

  15. Strategies for reservoir characterization and identification of incremental recovery opportunities in mature reservoirs in Frio Fluvial-Deltaic sandstones, south Texas: An example from Rincon Field, Starr County. Topical report

    SciTech Connect

    McRae, L.; Holtz, M.; Hentz, T.

    1995-11-01

    Fluvial-deltaic sandstone reservoirs in the United States are being abandoned at high rates, yet they still contain more than 34 billion barrels of unrecovered oil. The mature Oligocene-age fluvial-deltaic reservoirs of the Frio Formation along the Vicksburg Fault Zone in South Texas are typical of this class in that, after more than three decades of production, they still contain 61 percent of the original mobile oil in place, or 1.6 billion barrels. This resource represents a tremendous target for advanced reservoir characterization studies that integrate geological and engineering analysis to locate untapped and incompletely drained reservoir compartments isolated by stratigraphic heterogeneities. The D and E reservoir intervals of Rincon field, Starr County, South Texas, were selected for detailed study to demonstrate the ability of advanced characterization techniques to identify reservoir compartmentalization and locate specific infield reserve-growth opportunities. Reservoir architecture, determined through high-frequency genetic stratigraphy and facies analysis, was integrated with production history and facies-based petrophysical analysis of individual flow units to identify recompletion and geologically targeted infill drilling opportunities. Estimates of original oil in place versus cumulative production in D and E reservoirs suggest that potential reserve growth exceeds 4.5 million barrels. Comparison of reservoir architecture and the distribution of completions in each flow unit indicates a large number of reserve-growth opportunities. Potential reserves can be assigned to each opportunity by constructing an Sooh map of remaining mobile oil, which is the difference between original oil in place and the volumes drained by past completions.

  16. Genetic and grade and tonnage models for sandstone-hosted roll-type uranium deposits, Texas Coastal Plain, USA

    USGS Publications Warehouse

    Hall, Susan M.; Mihalasky, Mark J.; Tureck, Kathleen; Hammarstrom, Jane M.; Hannon, Mark

    2017-01-01

    The coincidence of a number of geologic and climatic factors combined to create conditions favorable for the development of mineable concentrations of uranium hosted by Eocene through Pliocene sandstones in the Texas Coastal Plain. Here 254 uranium occurrences, including 169 deposits, 73 prospects, 6 showings and 4 anomalies, have been identified. About 80 million pounds of U3O8 have been produced and about 60 million pounds of identified producible U3O8 remain in place. The development of economic roll-type uranium deposits requires a source, large-scale transport of uranium in groundwater, and deposition in reducing zones within a sedimentary sequence. The weight of the evidence supports a source from thick sequences of volcanic ash and volcaniclastic sediment derived mostly from the Trans-Pecos volcanic field and Sierra Madre Occidental that lie west of the region. The thickest accumulations of source material were deposited and preserved south and west of the San Marcos arch in the Catahoula Formation. By the early Oligocene, a formerly uniformly subtropical climate along the Gulf Coast transitioned to a zoned climate in which the southwestern portion of Texas Coastal Plain was dry, and the eastern portion humid. The more arid climate in the southwestern area supported weathering of volcanic ash source rocks during pedogenesis and early diagenesis, concentration of uranium in groundwater and movement through host sediments. During the middle Tertiary Era, abundant clastic sediments were deposited in thick sequences by bed-load dominated fluvial systems in long-lived channel complexes that provided transmissive conduits favoring transport of uranium-rich groundwater. Groundwater transported uranium through permeable sandstones that were hydrologically connected with source rocks, commonly across formation boundaries driven by isostatic loading and eustatic sea level changes. Uranium roll fronts formed as a result of the interaction of uranium-rich groundwater

  17. Facies and diagenesis of Triassic (Austrian alpine) and upper Permian (New Mexico-Texas) platform-margin carbonates: a comparison

    SciTech Connect

    Mazzullo, S.J.; Lobitzer, H.

    1988-02-01

    Platform-margin carbonates of the Austrian Middle and basal Upper Triassic (Carnian) (Wettersteinkalk) and Upper Permian (Capitan reef, Guadalupian) are similar in terms of facies development, biota, and syndepositional diagenetic fabrics. These similarities are noteworthy because of their occurrence across the Permian-Triassic boundary, and the fact that these carbonates are distinct from younger (Upper Triassic Dachsteinkalk) depositional systems. The Upper Permian and Middle to basal Upper Triassic were deposited as subdued rimmed platforms with component lagoonal, reef-flat, reef, and fore-reef facies belts. The reef facies appear to represent upper slope marginal mounds, and consist mainly of sponges, solitary corals, Tubiphytes, and various encrusting biota; typically, this facies is pervasively marine cemented. The reef-flat facies consist of similarly lithified biograin-stones deposited in high-energy wave-base zones along the platform margins. By contrast, steep rimmed platforms with massive framework coral buildups and relatively less syndepositional marine cements dominate in Upper Triassic units (e.g., Dachsteinkalk, Steinplatte reef). Proximal fore-reef beds in the Upper Permian and Middle to basal Upper Triassic are characterized by carbonate-clast debris cemented by coarse crystalline carbonate. The precipitation of this cement (grossoolith) may have occurred during early shallow burial of the fore-reef beds. Similar depositional and diagenetic facies are poorly developed in the Upper Triassic, instead being represented mainly by bedded micrites.

  18. Analysis of Fault Permeability Using Mapping and Flow Modeling, Hickory Sandstone Aquifer, Central Texas

    SciTech Connect

    Nieto Camargo, Jorge E. Jensen, Jerry L.

    2012-09-15

    Reservoir compartments, typical targets for infill well locations, are commonly created by faults that may reduce permeability. A narrow fault may consist of a complex assemblage of deformation elements that result in spatially variable and anisotropic permeabilities. We report on the permeability structure of a km-scale fault sampled through drilling a faulted siliciclastic aquifer in central Texas. Probe and whole-core permeabilities, serial CAT scans, and textural and structural data from the selected core samples are used to understand permeability structure of fault zones and develop predictive models of fault zone permeability. Using numerical flow simulation, it is possible to predict permeability anisotropy associated with faults and evaluate the effect of individual deformation elements in the overall permeability tensor. We found relationships between the permeability of the host rock and those of the highly deformed (HD) fault-elements according to the fault throw. The lateral continuity and predictable permeability of the HD fault elements enhance capability for estimating the effects of subseismic faulting on fluid flow in low-shale reservoirs.

  19. [X-ray radiography as a method of detailing the analysis of sedimentary facies, based on example of the Cergowa sandstones (Flysch Carpathians)].

    PubMed

    Pszonka, Joanna; Wendorff, Marek; Jucha, Katarzyna; Bartynowska, Karolina; Urbanik, Andrzej

    2013-01-01

    The paper presents the X-ray radiography as a method useful for the visualization of sedimentary structures in macroscopically homogeneous rocks. The radiographic analysis presented here bases on the example the Cergowa turbidite sandstones. The applied technique reveals that some of the apparently homogeneus Cergowa sandstones possess internal sedimentary structure of cross-lamination, which reflects on the sedimentological interpretation of the depositional mechanisms of this rock unit. This is the first application of this method in research on the Carpathian Flysch sedimentation.

  20. Chemical effects of carbon dioxide sequestration in the Upper Morrow Sandstone in the Farnsworth, Texas, hydrocarbon unit

    SciTech Connect

    Ahmmed, Bulbul; Appold, Martin S.; Fan, Tianguang; McPherson, Brian J. O. L.; Grigg, Reid B.; White, Mark D.

    2016-03-01

    Numerical geochemical modeling was used to study the effects on pore-water composition and mineralogy from carbon dioxide (CO2) injection into the Pennsylvanian Morrow B Sandstone in the Farnsworth Unit in northern Texas to evaluate its potential for long-term CO2 sequestration. Speciation modeling showed the present Morrow B formation water to be supersaturated with respect to an assemblage of zeolite, clay, carbonate, mica, and aluminum hydroxide minerals and quartz. The principal accessory minerals in the Morrow B, feldspars and chlorite, were predicted to dissolve. A reaction-path model in which CO2 was progressively added up to its solubility limit into the Morrow B formation water showed a decrease in pH from its initial value of 7 to approximately 4.1 to 4.2, accompanied by the precipitation of small amounts of quartz, diaspore, and witherite. As the resultant CO2-charged fluid reacted with more of the Morrow B mineral matrix, the model predicted a rise in pH, reaching a maximum of 5.1 to 5.2 at a water–rock ratio of 10:1. At a higher water–rock ratio of 100:1, the pH rose to only 4.6 to 4.7. Diaspore, quartz, and nontronite precipitated consistently regardless of the water–rock ratio, but the carbonate minerals siderite, witherite, dolomite, and calcite precipitated at higher pH values only. As a result, CO2 sequestration by mineral trapping was predicted to be important only at low water–rock ratios, accounting for a maximum of 2% of the added CO2 at the lowest water–rock ratio investigated of 10:1, which corresponds to a small porosity increase of approximately 0.14% to 0.15%.

  1. Diagenesis of the Carrizo sandstone at Bulter salt dome, East Texas Basin: Implications for paleofluid-flow

    SciTech Connect

    Smith, J.S.

    1996-09-01

    The calcite- and pyrite-cemented Eocene Carrizo sandstone on the flank of Butler salt dome in East Texas was formed by processes similar to those that form calcite cap rocks throughout the Gulf Coast. Isotopic evidence indicates that the bacterial degradation of hydrocarbons combined with the venting of deep sour gas and the dissolution of anhydrite from the dome resulted in the precipitation of these cements. Identification of the origins of these cements has lead to a better understanding of the paleofluid-flow associated with the dome. The Carrizo is a diagenetic quartzarenite with 42-50% concretionary calcite and pyrite cements. The calcite cement is bound to the northwest by a pyrite-cemented normal fault radial to the dome while the pyrite is found on both sides of the fault. Calcite {delta}{sup 13}C (-18 to -37 {per_thousand} (PDB)) and {delta}{sup 18}O (-6 to -9{per_thousand} (PDB)) show a mixed source of both waters (meteoric and deep) and hydrocarbons (oil, gas, and lignite). Heavy pyrite {delta}{sup 34}S (12-15 {per_thousand} (CDI)) represents H{sub 2}S supply from deep sour gas. Deep waters, methane, and H{sub 2}S migrated up the dome flank and out the fault into the Carrizo, already containing oil and lignite, and pyrite precipitated along the fault and in adjacent sediments. Bacteria oxidized the hydrocarbons and, with the meteoric and formation waters, formed bicarbonate. Calcium bearing fluids from the dome moved into the Caffizo, and calcite began to precipitate. However, pyrite cement along the fault prevented northwestern migration of the fluids, confining calcite precipitation to the southeast.

  2. Wilcox sandstone reservoirs in the deep subsurface along the Texas Gulf Coast: their potential for production of geopressured geothermal energy. Report of Investigations No. 117

    SciTech Connect

    Debout, D.G.; Weise, B.R.; Gregory, A.R.; Edwards, M.B.

    1982-01-01

    Regional studies of the lower Eocene Wilcox Group in Texas were conducted to assess the potential for producing heat energy and solution methane from geopressured fluids in the deep-subsurface growth-faulted zone. However, in addition to assembling the necessary data for the geopressured geothermal project, this study has provided regional information of significance to exploration for other resources such as lignite, uranium, oil, and gas. Because the focus of this study was on the geopressured section, emphasis was placed on correlating and mapping those sandstones and shales occurring deeper than about 10,000 ft. The Wilcox and Midway Groups comprise the oldest thick sandstone/shale sequence of the Tertiary of the Gulf Coast. The Wilcox crops out in a band 10 to 20 mi wide located 100 to 200 mi inland from the present-day coastline. The Wilcox sandstones and shales in the outcrop and updip shallow subsurface were deposited primarily in fluvial environments; downdip in the deep subsurface, on the other hand, the Wilcox sediments were deposited in large deltaic systems, some of which were reworked into barrier-bar and strandplain systems. Growth faults developed within the deltaic systems, where they prograded basinward beyond the older, stable Lower Cretaceous shelf margin onto the less stable basinal muds. Continued displacement along these faults during burial resulted in: (1) entrapment of pore fluids within isolated sandstone and shale sequences, and (2) buildup of pore pressure greater than hydrostatic pressure and development of geopressure.

  3. Architectural variability of confined turbidite sheet-sands: facies, geometry and infill of associated elementary channels. Examples from the Trois Evêchés Basin, Annot Sandstone Formation, SE France

    NASA Astrophysics Data System (ADS)

    Etienne, S.; Mulder, T.; Pace, A.; Bez, M.; Desaubliaux, G.

    2012-04-01

    The worldwide known Annot Sandstone Formation has been considered as a reference of confined siliciclastic turbidite system. This formation crops out in SE France and represents the Upper Eocene to Lower Oligocene gravitary infill of complex foreland basins, developed in front of the Alpine thrusts. This system can be assimilated as a sand-rich turbidite ramp, sourced by multiple fan deltas leading to topographically complex sub-basins. Highly bypassing channelized systems dominate in the most proximal and most confined areas. They distally evolve to relatively less confined areas, in which sedimentary bodies appear to be more continuous and homogenous on a regional scale. These last architectural elements, defined as sheet-sands or depositional lobes, have been the focus of this study in poorly documented areas. From an important dataset made of very high resolution outcrop correlations (gathered mainly in the Trois Evêchés and Lauzanier sub-basins), we have quantified the complex distribution of sedimentary facies and structures, grain-size and key surfaces in sand-rich sheets. This was done to understand their variability from depositional event to architectural element scales and to better characterize dimensions and characteristics of their components. Six main types of architectural elements were defined, composed of both channelized and unchannelized elements. Channelized units show a high variability in terms of facies, geometry and patterns of infill that are related to multiple erosional and depositional processes, which will be discussed. We notably relate some evidences of sinuous channels, represented by lateral accretion deposits in the channel complex axis and by low angle cross-bedded facies. We interpret this particular facies as the result of flow deconfinement and overbanks above channel margins. The stratigraphic analysis of elementary objects allows us to propose a genetic model and a spatial distribution model of sheet-sand architectural

  4. Facies analysis and sequence stratigraphic framework of upper Campanian strata (Neslen and Mount Garfield formations, Bluecastle Tongue of the Castlegate sandstone, and Mancos shale), Eastern Book cliffs, Colorado and Utah

    USGS Publications Warehouse

    Kirschbaum, Mark A.; Hettinger, Robert D.

    2004-01-01

    Facies and sequence-stratigraphic analysis identifies six high-resolution sequences within upper Campanian strata across about 120 miles of the Book Cliffs in western Colorado and eastern Utah. The six sequences are named after prominent sandstone units and include, in ascending order, upper Sego sequence, Neslen sequence, Corcoran sequence, Buck Canyon/lower Cozzette sequence, upper Cozzette sequence, and Cozzette/Rollins sequence. A seventh sequence, the Bluecastle sequence, is present in the extreme western part of the study area. Facies analysis documents deepening- and shallowing- upward successions, parasequence stacking patterns, downlap in subsurface cross sections, facies dislocations, basinward shifts in facies, and truncation of strata.All six sequences display major incision into shoreface deposits of the Sego Sandstone and sandstones of the Corcoran and Cozzette Members of the Mount Garfield Formation. The incised surfaces represent sequence-boundary unconformities that allowed bypass of sediment to lowstand shorelines that are either attached to the older highstand shorelines or are detached from the older highstand shorelines and located southeast of the main study area. The sequence boundary unconformities represent valley incisions that were cut during successive lowstands of relative sea level. The overlying valley-fill deposits generally consist of tidally influenced strata deposited during an overall base level rise. Transgressive surfaces can be traced or projected over, or locally into, estuarine deposits above and landward of their associated shoreface deposits. Maximum flooding surfaces can be traced or projected landward from offshore strata into, or above, coastal-plain deposits. With the exception of the Cozzette/Rollins sequence, the majority of coal-bearing coastal-plain strata was deposited before maximum flooding and is therefore within the transgressive systems tracts. Maximum flooding was followed by strong progradation of

  5. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in frio fluvial-deltaic sandstone reservoirs at South Texas. Annual report, October 1994--October 1995

    SciTech Connect

    Holtz, M.; Knox, P.; McRae, L.

    1996-02-01

    The Frio Fluvial-Deltaic Sandstone oil play of South Texas has produced nearly 1 billion barrels of oil, yet it still contains about 1.6 billion barrels of unrecovered mobile oil and nearly the same amount of residual oil resources. Interwell-scale geologic facise models of Frio Fluvial-deltaic reservoirs are being combined with engineering assessments and geophysical evaluations in order to determine the controls that these characteristics exert on the location and volume or unrecovered mobile and residual oil. Progress in the third year centered on technology transfer. An overview of project tasks is presented.

  6. Dissolved-solids concentrations and hydrochemical facies in water of the Edwards-Trinity aquifer system, west-central Texas

    USGS Publications Warehouse

    Bush, P.W.; Ulery, R.L.; Rittmaster, R.L.

    1994-01-01

    Much of the Edwards-Trinity aquifer system contains freshwater, but sizable parts contain marginally fresh or slightly saline water. The predominant water type in the aquifer system is calcium bicarbonate; however, one of seven other hydrochemical facies characterizes the water in places. The median dissolved-solids concentration of water samples from the Edwards aquifer in the Balcones fault zone is 297 mg/L (milligrams per liter); the interquartile range is 93 mg/L. In the freshwater zone of the Edwards aquifer updip of a freshwater/saline-water transition zone, the water is almost exclusively calcium bicarbonate. The median dissolved-solids concentration of water samples from the Trinity aquifer in the Hill Country is 537 mg/L and the interquartile range is 573 mg/L. Four bicarbonate and sulfate facies, spread vertically throughout the saturated section, characterize most of the Hill Country analyses; calcium bicarbonate predominates. The median concentration of dissolved solids in water samples from the Edwards-Trinity aquifer in the Edwards Plateau is 379 mg/L and the interquartile range is 547 mg/L. Freshwater is nearly everywhere in the southern and northeastern parts of the aquifer, and mostly slightly saline water is in the northwestern part. The distribution of hydrochemical facies shows a similar pattern to dissolved-solids concentration, with bicarbonate water nearly everywhere in the southern and northeastern parts of the aquifer. Sulfate and chloride facies characterize the northwestern part of the Edwards Plateau. The median concentration of dissolved solids among water samples from the Edwards-Trinity aquifer in the Trans-Pecos is 929 mg/L and the interquartile range is 1,626 mg/L. Fresh, calcium bicarbonate water predominates in the southern part, and more saline mixed and sulfate waters are the most common in the northwestern part.

  7. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio Fluvial-Deltaic Sandstone Reservoirs of South Texas

    SciTech Connect

    McRae, L.E.; Holtz, M.H.; Knox, P.R.

    1995-07-01

    The Frio Fluvial-Deltaic Sandstone Play of South Texas is one example of a mature play where reservoirs are being abandoned at high rates, potentially leaving behind significant unrecovered resources in untapped and incompletely drained reservoirs. Nearly 1 billion barrels of oil have been produced from Frio reservoirs since the 1940`s, yet more than 1.6 BSTB of unrecovered mobile oil is estimated to remain in the play. Frio reservoirs of the South Texas Gulf Coast are being studied to better characterize interwell stratigraphic heterogeneity in fluvial-deltaic depositional systems and determine controls on locations and volumes of unrecovered oil. Engineering data from fields throughout the play trend were evaluated to characterize variability exhibited by these heterogeneous reservoirs and were used as the basis for resource calculations to demonstrate a large additional oil potential remaining within the play. Study areas within two separate fields have been selected in which to apply advanced reservoir characterization techniques. Stratigraphic log correlations, reservoir mapping, core analyses, and evaluation of production data from each field study area have been used to characterize reservoir variability present within a single field. Differences in sandstone depositional styles and production behavior were assessed to identify zones with significant stratigraphic heterogeneity and a high potential for containing unproduced oil. Detailed studies of selected reservoir zones within these two fields are currently in progress.

  8. Production data as an indicator of gas reservoir heterogenesity in the Vicksburg S sandstones (Oligocene), McAllen Ranch field, Hidalgo County, Texas

    SciTech Connect

    Wermund, E.G.; Langford, R.P. )

    1990-09-01

    To assess reservoir heterogeneity in low-permeability Vicksburg S sandstone reservoirs in McAllen Ranch gas field, production and pressure histories of 49 wells were analyzed; predominant well spacing is 80 acres. These histories were compared both fieldwide and in local areas defined by faults or facies. Production is through casing perforations, which commonly extend over 600 ft gross intervals within vertically stacked potential reservoir sandstones. The S reservoir comprises five sand-rich intervals that together have produced 249 bcf of gas since 1965. Cumulative production per well ranges from 39 bcf for 24 years to 0.8 bcf in 11 years. Average cumulative production is 6.3 bcf per well. To date, the largest average monthly production for a well is over 360 Mmcf; the mean for average monthly production (based on publicly available data) for all wells is 30.5 Mmcf. There is poor correlation among gross thicknesses of perforated intervals and cumulative production (R = 0.024). Wellhead shut-in pressures range from 12,500 psi on completion to 1,300 psi at abandonment. Maps of cumulative production and normalized BHP/Z show good production/pressure correlations. The slopes of regression curves for (1) monthly production decline histories and (2) periodic tests of daily production of adjacent well pairs show little influence from adjacent well completions or refracturing, even at relatively close well spacing. Monthly production in a newly completed or refractured adjacent well commonly exceeds the last production rate of a nearby older well. Production and pressure histories in adjacent well pairs suggest that limited communication occurs between S sandstone reservoirs of paired wells. This limited communication may be a consequence of limited drainage radius due to low permeability and of stratigraphic/diagenetic heterogeneity within the reservoir.

  9. Frio sandstone reservoirs in the deep subsurface along the Texas Gulf Coast: their potential for production of geopressured geothermal energy

    SciTech Connect

    Bebout, D.G.; Loucks, R.G.; Gregory, A.R.

    1983-01-01

    Detailed geological, geophysical, and engineering studies conducted on the Frio Formation have delineated a geothermal test well site in the Austin Bayou Prospect which extends over an area of 60 square miles. A total of 800 to 900 feet of sandstone will occur between the depths of 13,500 and 16,500 feet. At leat 30 percent of the sand will have core permeabilities of 20 to 60 millidarcys. Temperature at the top of the sandstone section will be 300/sup 0/F. Water, produced at a rate of 20,000 to 40,000 barrels per day, will probably have to be disposed of by injection into shallower sandstone reservoirs. More than 10 billion barrels of water are in place in these sandstone reservoirs of the Austin Bayou Prospect; there should be approximately 400 billion cubic feet of methane in solution in this water. Only 10 percent of the water and methane (1 billion barrels of water and 40 billion cubic feet of methane) will be produced without reinjection of the waste water into the producing formation. Reservoir simulation studies indicate that 90 percent of the methane can be produced with reinjection. 106 figures.

  10. Geologic description of the San Andres reservoir facies in the Mabee field

    SciTech Connect

    Miller, K.D. )

    1992-04-01

    The Mabee field is located in Andrews and Martin counties, Texas, approximately 16 mi northwest of Midland in the Permian basin. Production is from the upper Permian San Andres dolomite at an average depth of 4700 ft. The San Andres/Grayburg formations are the most prolific oil-producing formations in the Permian basin, with total production over 10 billion bbl, and an estimated additional 3.8 billion bbl to be recovered by conventional secondary and tertiary methods. The Mabee field has produced over 90 MMBO by primary and secondary methods since its discovery in 1943. A tertiary CO{sub 2} flood will be implemented in 1992. An essential prerequisite to a successful CO{sub 2} project is a detailed reservoir description and facies analysis. Examination of over 5000 ft of core established six major facies in an overall shallowing-upward sequence. The cap rock consists of dense anhydritic dolomites of the supratidal and oncolite facies. Production primarily is from the underlying dolomitized subtidal and ooid facies. Sandstones interfinger with the ooid facies, but are tightly cemented and act as barriers to fluid migration. The lower-most open-marine facies is below the oil/water contact for the field. Reservoir characterization improves the planning and operation of an enhanced recovery project.

  11. Texas

    USGS Publications Warehouse

    ,

    1999-01-01

    In 1997, the Texas Legislature passed a comprehensive revision to the Texas Water Code. This legislation (Senate Bill 1) changed water planning in Texas from a statewide to a regional activity. By September 2001, the 16 regions created by Senate Bill 1 must produce water plans to address their water needs during drought-of-record conditions, and must identify water-management strategies for periods when streamflows, reservoir storage, and groundwater levels are 50 and 75 percent of normal.

  12. Evaluation of Geologic CO2 Sequestration Potential of the Morrow B Sandstone in the Farnsworth, Texas Hydrocarbon Field using Reactive Transport Modeling

    NASA Astrophysics Data System (ADS)

    Khan, R. H.; Appold, M. S.; McPherson, B. J. O. L.; Balch, R. S.; White, M. D.

    2016-12-01

    The objective of the present study is to evaluate the effects of injection of CO2 into the Morrow B Sandstone reservoir in the Farnsworth, Texas hydrocarbon field in order to predict the reservoir's potential for long term CO2 sequestration. Three-dimensional reactive transport simulations were conducted using the TOUGHREACT software and the ECO2N equation of state on a grid representing the Morrow B Sandstone and parts of the adjacent Morrow Shale layers. Supercritical CO2 was injected in the simulation through nine wells for ten years at rates on the order of several kg/s at a constant enthalpy of 3.01 x 105 J/kg. The simulations showed most of the injected CO2 to dissolve into the formation water and to migrate westward. An immiscible fraction of the injected CO2 accumulated near the wells during the injection period, reaching a peak saturation of 0.98. After injection ceased, the immiscible CO2 gradually dissolved into the formation water over the next several decades. The simulations predicted minor dissolution of albite, chlorite, and illite, minerals that are present in the reservoir matrix. The simulations also predicted minor precipitation of dolomite, kaolinite, smectite, and quartz within the aqueous CO2 plume. However, the amounts of mineral precipitation and dissolution were not great enough to cause significant changes in the porosity and permeability of the reservoir, most likely because of its quartz-rich nature (about 85% by volume), which together with the low salinity of the formation water offer little reaction potential for the injected CO2. These results suggest that for the century-scale time scales simulated, CO2 should be sequestered mainly by hydrodynamic trapping in the Morrow B Sandstone within the boundaries of the Farnsworth field. Funding for this project is provided by the U.S. Department of Energy's National Energy Technology Laboratory through the Southwest Partnership on Carbon Sequestration under Award No. DE-FC26-05NT42591.

  13. Open system diagenesis and the los of provenance signatures: isotopic and elemental data from sandstones, Frio Formation, south Texas

    SciTech Connect

    Land, L.S.; Mack, L.E.; Milliken, K.L. ); MacPherson, G.L. )

    1990-05-01

    Oligocene Frio sandstones in which detrital feldspars are completely altered typically contain authigenic minerals that exceed 30% of the rock volume. Elemental and isotopic analyses of whole rocks show that authigenesis is accompanied by both gain and loss of material. Subsurface sandstones for elemental and isotopic analysis were sampled from approximately 3,000-14,000 ft (0.9-4.3 km). Over this depth range, dissolution and minor albitization of detrital K-feldspar is accompanied by loss of 2 to 3 wt.% of K{sub 2}O from the whole rock. Loss of about 50% of the initial strontium also correlates with alteration of detrital feldspars. {sup 87}Sr/{sup 86}Sr for whole-rock and silicate fractions change with depth as strontium characteristic of the detrital fraction is replaced by more radiogenic strontium derived from deeper in the basin. Aluminum, titanium, phosphorous, manganese, and barium also exhibit trends compatible with net export, but uncertainties about initial variation remain. Trends for silicon, sodium, iron, boron, and lithium are equivocal. Magnesium gain accompanies precipitation of authigenic chlorite. Whole-rock calcium values are dominated by calcite that includes both detrital and authigenic components. Significant dissolution of the detrital carbonate component does not occur, and calcium in authigenic carbonate exceeds by about five times the calcium released during destruction of detrital silicates, thus requiring considerable calcium and CO{sub 2} import. Material transfer on the scale observed suggests that simple burial diagenesis is not a closed-system process for several major elements and introduces a major obstacle to the use of elemental data for provenance interpretation.

  14. Revitalizing a mature oil play: Strategies for finding and producing oil in Frio Fluvial-Deltaic Sandstone reservoirs of South Texas

    SciTech Connect

    Knox, P.R.; Holtz, M.H.; McRae, L.E.

    1996-09-01

    Domestic fluvial-dominated deltaic (FDD) reservoirs contain more than 30 Billion barrels (Bbbl) of remaining oil, more than any other type of reservoir, approximately one-third of which is in danger of permanent loss through premature field abandonments. The U.S. Department of Energy has placed its highest priority on increasing near-term recovery from FDD reservoirs in order to prevent abandonment of this important strategic resource. To aid in this effort, the Bureau of Economic Geology, The University of Texas at Austin, began a 46-month project in October, 1992, to develop and demonstrate advanced methods of reservoir characterization that would more accurately locate remaining volumes of mobile oil that could then be recovered by recompleting existing wells or drilling geologically targeted infill. wells. Reservoirs in two fields within the Frio Fluvial-Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas, a mature play which still contains 1.6 Bbbl of mobile oil after producing 1 Bbbl over four decades, were selected as laboratories for developing and testing reservoir characterization techniques. Advanced methods in geology, geophysics, petrophysics, and engineering were integrated to (1) identify probable reservoir architecture and heterogeneity, (2) determine past fluid-flow history, (3) integrate fluid-flow history with reservoir architecture to identify untapped, incompletely drained, and new pool compartments, and (4) identify specific opportunities for near-term reserve growth. To facilitate the success of operators in applying these methods in the Frio play, geologic and reservoir engineering characteristics of all major reservoirs in the play were documented and statistically analyzed. A quantitative quick-look methodology was developed to prioritize reservoirs in terms of reserve-growth potential.

  15. Factors controlling porosity and permeability in geopressured Frio sandstone reservoirs, general crude oil/Department of Energy Pleasant Bayou test wells, Brazoria County, Texas

    SciTech Connect

    Loucks, R.G.; Richman, D.L.; Milliken, K.L.

    1980-06-01

    Reservoir characteristics of Frio sandstones in the GCO/DOE Pleasant Bayou No. 1 and No. 2 wells are influenced by depositional environment, sandstone composition, and diagenetic history. The sandstones and shales were deposited in deltaic and continental slope environments. Fluvial channel and distributary-mouth bar sandstones are most favorable for development and preservation of the porosity needed for a geothermal reservoir. Sandstones in the geopressured zone are lithic arkoses and feldspathic litharenites. Depositional matric (detrital material less than 20 micrometers in size) occluded most or all of the potential primary porosity between grains in many of the fine-grained sandstones at the time of deposition. Even if cements are present, dissolution of grains and development of secondary porosity do take place. Permeable geopressured sandstone reservoirs are characterized by porosity that is dominantly secondary. 12 references.

  16. Paint Rock and southwest Paint Rock fields, Concho County, Texas: Strawn analogs of modern island carbonate facies of Ambergris Cay, Belize

    SciTech Connect

    Reid, A.M.; Mazzullo, S.J.

    1987-02-01

    Lower Strawn (Desmoinesian Goen Limestone) reservoirs at Paint Rock and Southwest Paint Rock fields are a complex of carbonate and associated facies interpreted as having been deposited in various environments on and around large, emergent islands on shallow carbonate shelves. The origin and geometries of the component lithofacies in these fields, and their reservoir diagenetic histories, are similar to those presently accumulating on Ambergris Cay, a linear island complex on the northern shelf of Belize. Paint Rock field originated as a narrow, elongate Chaetetes reef trend that formed the foundation on which the overlying island facies were deposited. As on Ambergris Cay, these reef limestones developed extensive porosity during postdepositional subaerial exposure due to meteoric leaching. In contrast, Southwest Paint Rock field is cored by older island deposits rather than reef limestones. With ensuing stillstand or subsequent sea level rise, beach grainstones were deposited along the windward and leeward margins of the foundation highs in these fields. Tight lagoonal micrites and coals (peat-swamp facies) comprise the inner island facies, and are locally associated with porous supratidal dolomites. These island complexes are transected locally by tidal channels that are filled with nonporous micrites. Repeated sea level fluctuations during the history of these fields resulted in a characteristic cyclic stratigraphy of stacked island facies and reservoirs. The reservoirs in the field are developed in the bedrock or older island cores, as well as in the overlying beach facies and supratidal dolomites. These fields are mappable as linear stratigraphic traps with low-relief closure, and are readily identified by subsurface geologic and facies analyses. Similar shelf island-type fields analogous to these strawn and Holocene Belizean examples are found throughout the Midland basin and Eastern shelf.

  17. National Uranium Resource Evaluation: Lawton Quadrangle, Oklahoma and Texas

    SciTech Connect

    Al-Shaieb, Z.; Thomas, R.G.; Stewart, G.F.

    1982-04-01

    Uranium resources of the Lawton Quadrangle, Oklahoma and Texas, were evaluated to a depth of 1500 m using National Uranium Resource Evaluation criteria. Five areas of uranium favorability were delineated. Diagenetically altered, quartzose and sublithic, eolian and marginal-marine sandstones of the Permian Rush Springs Formation overlying the Cement Anticline are favorable for joint-controlled deposits in sandstone, non-channel-controlled peneconcordant deposits, and Texas roll-front deposits. Three areas contain lithologies favorable for channel-controlled peneconcordant deposits: arkosic sandstones and granule conglomerates of the Permian Post Oak Conglomerate south of the Wichita Mountains; subarkosic and sublithic Lower Permian fluvio-deltaic and coastal-plain sandstones of the eastern Red River Valley; and subsurface arkosic, subarkosic, and sublithic alluvial-fan and fan-delta sandstones of the Upper Pennsylvanian-Lower Permian sequence in the eastern Hollis Basin. The coarse-grained facies of the Cambrian Quanah Granite and genetically related aplite and pegmatite dikes in the Wichita Mountains are favorable for orthomagmatic and autometasomatic deposits, respectively.

  18. Shelf sandstones of Twowells tongue, Dakota Sandstone, northwestern New Mexico

    SciTech Connect

    Wolter, N.R.; Nummedal, D.

    1988-01-01

    The Dakota Sandstone of northwestern New Mexico is composed of basal continental strata and three marine sandstone tongues, which intertongue was the Mancos Shale. The late Cenomanian Twowells tongue was the last tongue deposited in the Dakota transgressive systems tract. This tongue is most commonly gradationallly underlain by the Whitewater Arroyo shale tongue and abruptly overlain by the Rio Salado tongue of the Mancos Shale. Data collected from 85 outcrop sections and 180 electric well logs, from the San Juan, Acoma, and Zuni Basins, indicates that the Twowells tongue represents three phases of marine deposition. The White-water Arroyo shale tongue, the muddy burrowed facies, and the horizontally bedded facies of the Twowells tongue represent a shoaling-upward sequence (regressive phase) of shelf and shoreface deposition. The regressive phase is sharply overlain by an inferred transgressive cross-bedded facies. Erosional scour and an extensive pebble lag mark the contact between the regressive and the transgressive facies. In the Acoma basin, the transgressive cross-bedded facies describes a north-south oriented shelf-sand ridge 32 km long, 18 km wide, and 32 m thick.

  19. Depositional and diagenetic controls on porosity permeability and oil production in McFarland/Magutex (Queen) reservoirs, Andrews County, west Texas

    SciTech Connect

    Holtz, M.H. )

    1991-03-01

    The McFarland/Magutex Queen reservoir complex lies along the northeastern edge of the Central basin platform in the west Texas Permian basin and produces oil from the Permian Queen Formation. Current production from this complex totals 42 million stock-tank barrels (MMSTB) of an estimated 219 MMSTB of original oil in place, with an estimated 90 MMSTB of remaining mobile oil (RMO). The gross pay interval contains two parasequences consisting of progradational, 30-ft-thick, upward-shoaling facies packages. Facies include shoreface, mixed tidal channel and intertidal flat, and supratidal. Elongate shoreface facies are characterized by poorly consolidated, massive to thinly laminated sandstones. The supratidal facies, which act as permeability barriers, are characterized by algal-laminated dolostone and nodular, laminated, and massive anhydrite containing halite and gypsum pseudomorphs. Highest production and the largest amount of the 90 MMSTB of RMO is associated with the shoreface and tidal-channel facies. Bulk pore volume storage capacity and permeability are also highest within these two facies. Sandstones are arkosic, containing anhydrite and dolomite cements. Accessory minerals are clays, authigenic feldspar, and dolomite. Three main pore types are recognized: interparticle, moldic and intraconstituent, and micropores. Moldic and intraconstituent porosity is associated with leached feldspars and anhydrite cement dissolution. Microporosity is associated with syndepositional, grain-coating corrensite, dissolution-enhanced feldspar cleavage planes, and authigenic multifaceted dolomite. Microporosity derived from clays and dolomite is formed preferentially in tidal-channel and intertidal flat facies.

  20. Evolution of salt structures, East Texas Diapir Province, Part 1: Sedimentary record of Halokinesis

    SciTech Connect

    Seni, S.J.; Jackson, M.P.A.

    1983-08-01

    Post-Aptian (post-112Ma) strata in the East Texas basin were strongly influenced by halokinesis and therefore record the evolution of associated salt structures. Domeinduced changes in patterns of sandstone distribution, depositional facies, and reef growth indicate that thickness variations in strata surrounding domes were caused by syndepositional processes rather than by tectonic distortion. Salt domes in the East Texas basin exhibit three stages of growth: pillow, diapir, and post-diapir, each of which affected surrounding strata differently. Pillow growth caused broad uplift of strata over the crest of the pillows; the resulting topographic swell influenced depositional trends and was susceptible to erosion. Fluvial channel systems bypassed pillow crests and stacked vertically in primary peripheral sinks on the updip flanks of the pillows. Diapir growth was characterized by expanded sections of shelf and deltaic strata in secondary peripheral sinks around the diapirs. Lower Cretaceous reefs on topographic saddles between secondary peripheral sinks now host major oil production at Fairway field. Post-diapir crestal uplifts and peripheral subsidence affected smaller areas than did equivalent processes during pillow or diapir stages. Documented facies variations over and around domes at different stages of growth enable prediction of subtle facies-controlled hydrocarbon traps. Facies-controlled traps are likely to be the only undiscovered ones remaining in mature petroliferous basins such as the East Texas basin.

  1. Evolution of salt structures, East Texas diapir province, part 1: sedimentary record of halokinesis

    SciTech Connect

    Seni, S.J.; Jackson M.P.A.

    1983-08-01

    Post-Aptian (post-112 Ma) strata in the East Texas basin were strongly influenced by halokinesis and therefore record the evolution of associated salt structures. Dome-induced changes in patterns of sandstone distribution, depositional facies, and reef growth indicate that thickness variations in strata surrounding domes were caused by syndepositional processes rather than by tectonic distortion. Salt domes in the East Texas basin exhibit three stages of growth: pillow, diapir, and post-diapir, each of which affected surrounding strata differently. Pillow growth caused broad uplift of strata over the crest of the pillows; the resulting topographic swell influenced depositional trends and was susceptible to erosion. Fluvial channel systems bypassed pillow crests and stacked vertically in primary peripheral sinks on the updip flanks of the pillows. Diapir growth was characterized by expanded sections of shelf and deltaic strata in secondary peripheral sinks around the diapirs. Lower Cretaceous reefs on topographic saddles between secondary peripheral sinks now host major oil production at Fairway field. Post-diapir crestal uplifts and peripheral subsidence affected smaller areas than did equivalent processes during pillow or diapir stages. Documented facies variations over and around domes at different stages of growth enable prediction of subtle facies-controlled hydrocarbon traps. Facies-controlled traps are likely to be the only undiscovered ones remaining in mature petroliferous basins such as the East Texas basin.

  2. Depositional facies of hydrocarbon reservoirs of upper Cherokee Group, Anadarko basin

    SciTech Connect

    Puckette, J.O.; Al-Shaieb, Z. )

    1989-08-01

    The Desmoinesian upper Cherokee Group sequence in the Anadarko basin is the subsurface equivalent of the Cabaniss Group of eastern Oklahoma. This sequence includes the Pink limestone, Skinner sandstone, Verdigris limestone, and Prue sandstone intervals. The upper Skinner sandstone, which has not been well documented, is an important hydrocarbon-producing reservoir in the Anadarko basin. The Skinner sandstone is represented by channel, delta-front-prodelta, and shallow marine facies. Channel facies consist of a primary elongate trend extending 40 mi southeast-northwest across Custer and Roger Mills Counties, Oklahoma. Several small secondary channels trending northeast-southwest were also observed. Active channel-fill sequences in the primary trend exceed 100 ft in thickness and represent the major producing reservoir of the upper Skinner sandstone. Delta-front-prodelta sequences are dominated by shale and interbedded sandstone-shale units. Shallow marine facies consist of massive coarsening-upward units that reach 300 ft in thickness. This facies belt is broad and slightly elongated, approximately 12 mi wide by 20 mi long, and trends northeast-southwest somewhat normal to channel facies orientation. Lithologically, the upper Skinner channel sandstone is feldspathic litharenite with abundant feldspar and quartz overgrowth. Both primary and secondary porosity were observed in the upper Skinner sandstone. Secondary porosity evolved mainly from dissolution of feldspar and lithic fragments. However, extensive cementation in the shallow marine facies has reduced porosity to negligible amounts and consequently reduced reservoir quality.

  3. Trace-fossil and storm-deposit relationships of San Carlos formation, west Texas

    SciTech Connect

    Metz, C.L.; Bednarski, S.P.

    1986-05-01

    Two distinct assemblages of trace fossils are preserved in the storm deposits in delta-front facies of the Upper Cretaceous San Carlos Formation, west Texas. The assemblages represent two widely differing responses to storm deposition and sediment-trace-fossil relationships, indicating that other environmental parameters, probably water depth and oxygen levels, influenced trace-fossil distribution within the San Carlos delta front. Evidence of the storm-deposited nature of the sandstones includes a scoured basal contact, planar to hummocky cross-stratification, and a upper contact that is either ripple marked or is gradational with overlying shales.

  4. The Early Gulf of Mexico as a Subaerial Basin Below Sea Level (SABSEL) Basin. Evidence from Stratigraphy and Facies of Luanne salt, Norphlet sandstone and Smackover Brown Dense Formations.

    NASA Astrophysics Data System (ADS)

    Cassidy, M. M.

    2016-12-01

    Many workers recognize that large salt deposits form in post-rift sag basins which were subaerial and susceptible to rapid flooding from adjacent oceansl. I have termed these basins "subaerial basins below sea level" or "SABSEL" basins. A key marker of SABSEL basins are terrestrial sediments immediately overlain by deepwater sediments with no transition. Desert deposits -including Aeolian dunes- are preserved in the adiabatically heated depression. Dunes are not eroded by transgressing seas but are drowned by rising water as in a bath tub. They maintain their shape. Deepwater marine black shales or limestones drape the dunes. The Southern North sea is an example. Above the original marine shale over the dunes are evaporites. Winds descending into the basin were heated by adiabatic compression providing the very hot air need to allow survival of potassium salts. A similar situation was probably active during the Messinian salinity crisis in the Mediterranean basin, and the opening of the South Atlantic. In the Gulf of Mexico (GOM) a desert is on the Louann salt. Here the sea invaded the lows first to deposit the salt overlying tilted fault blocks of the opening basin, as in the Afar Triangle of Africa. In the GOM entry to the west fed in sea water, then closed. The Norphlet desert formed. Streams carried sands to the basin to be spread by winds where they willed, not limited to sand entry areas. Upon deposition their original weight depressed the salt. Seismic shows depressions in the salt but the dunes are high at the top Norphlet, forming distinctive small "eyes" at the top salt. The 600 foot dunes are draped by deep water dolomitic finely laminated organic rich black/ brown shale, the Brown Dense Facies of the Smackover formation. The lack of reworking of the dunes found by detailed seismic is distinctive of deposition in a SABSEL basin. The overlap of terrestrial sediments by deep water deposition is good evidence of sudden flooding. In summary this vertical

  5. Sedimentary Facies of the West Crocker Formation North Kota Kinabalu-Tuaran Area, Sabah, Malaysia

    NASA Astrophysics Data System (ADS)

    Mohamed, Azfar; Hadi Abd Rahman, Abdul; Suhaili Ismail, Mohd

    2016-02-01

    Newly outcrops exposed in the West Crocker Formation have led to the detail sedimentolgical analysis of the formation. Eight sedimentary facies have been recognised in which it was divided into three main groups: (1) sand-dominated facies (F1-F2), (2) poorly- sorted unit mixed sand and mud-dominated facies (F3), and (3) mud-dominated facies (F4-F5). These are: F1- graded sandstone (massive to planar laminated), F2-ripple-cross laminated, wavy and convolute lamination sandstone, F3-chaotic beds of mixed sandstone and mudstone blocks and clasts, F4-lenticular bedded of sandstone, and F5-shale. The studies of the formation has come out that it was deposited in a sand-rich submarine fan with specific location located at (1) inner fan channel-levee complex; (2) mid-fan channelised lobes, and (3) outer fan.

  6. Geoscience/engineering characterization of the interwell environment in carbonate reservoirs based on outcrop analogs, Permian Basin, West Texas and New Mexico-stratigraphic hierarchy and cycle stacking facies distribution, and interwell-scale heterogeneity: Grayburg Formation, New Mexico. Final report

    SciTech Connect

    Barnaby, R.J.; Ward, W.B.; Jennings, J.W. Jr.

    1997-06-01

    The Grayburg Formation (middle Guadalupian) is a major producing interval in the Permian Basin and has yielded more than 2.5 billion barrels of oil in West Texas. Grayburg reservoirs have produced, on average, less than 30 percent of their original oil in place and are undergoing secondary and tertiary recovery. Efficient design of such enhanced recovery programs dictates improved geological models to better understand and predict reservoir heterogeneity imposed by depositional and diagenetic controls. The Grayburg records mixed carbonate-siliciclastic sedimentation on shallow-water platforms that rimmed the Delaware and Midland Basins. Grayburg outcrops in the Guadalupe and Brokeoff Mountains region on the northwest margin of the Delaware Basin present an opportunity to construct a detailed, three-dimensional image of the stratigraphic and facies architecture. This model can be applied towards improved description and characterization of heterogeneity in analogous Grayburg reservoirs. Four orders of stratigraphic hierarchy are recognized in the Grayburg Formation. The Grayburg represents a long-term composite sequence composed of four high-frequency sequences (HFS 1-4). Each HFS contains several composite cycles comprising two or more cycles that define intermediate-scale transgressive-regressive successions. Cycles are the smallest scale upward-shoaling vertical facies successions that can be recognized and correlated across various facies tracts. Cycles thus form the basis for establishing the detailed chronostratigraphic correlations needed to delineate facies heterogeneity.

  7. Lithogenetic stratigraphy of the Triassic Dockum Formation, Palo Duro Basin, Texas

    SciTech Connect

    Not Available

    1989-01-01

    Using approximately 350 well logs and cores from 4 wells, the author examines the depositional origin of the Dockum, discusses the distribution of lithofacies within the basin, and assesses the influences on trends in sandstone thickness. Outcrops were examined along the Eastern and Western Caprock Escarpments in Texas and eastern New Mexico, and facies interpretations were projected into the subsurface to improve regional analysis of the Dockum. Four new cores of subsurface Dockum were described and interpreted, forming the nucleus of subsurface lithofacies identification. The book focuses on the lower Dockum, within which the author identified four depositional sequences. These sequences, presented on cross sections and net-sandstone and paleogeographic maps, document a progression from continental-dominated depositional systems to lacustrine-dominated systems.

  8. Application of Advanced Reservoir Characterization, Simulation, and Production Optimization Strategies to Maximize Recovery in Slope and Basin Clastic Reservoirs, West Texas (Delaware Basin)

    SciTech Connect

    Andrew G. Cole; George B. Asquith; Jose I. Guzman; Mark D. Barton; Mohammad A. Malik; Shirley P. Dutton; Sigrid J. Clift

    1998-04-01

    The objective of this Class III project is to demonstrate that detailed reservoir characterization of clastic reservoirs in basinal sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost-effective way to recover more of the original oil in place by strategic infill-well placement and geologically based enhanced oil recovery. The study focused on the Ford Geraldine unit, which produces from the upper Bell Canyon Formation (Ramsey sandstone). Reservoirs in this and other Delaware Mountain Group fields have low producibility (average recovery <14 percent of the original oil in place) because of a high degree of vertical and lateral heterogeneity caused by depositional processes and post-depositional diagenetic modification. Outcrop analogs were studied to better interpret the depositional processes that formed the reservoirs at the Ford Geraldine unit and to determine the dimensions of reservoir sandstone bodies. Facies relationships and bedding architecture within a single genetic unit exposed in outcrop in Culberson County, Texas, suggest that the sandstones were deposited in a system of channels and levees with attached lobes that initially prograded basinward, aggraded, and then turned around and stepped back toward the shelf. Channel sandstones are 10 to 60 ft thick and 300 to 3,000 ft wide. The flanking levees have a wedge-shaped geometry and are composed of interbedded sandstone and siltstone; thickness varies from 3 to 20 ft and length from several hundred to several thousands of feet. The lobe sandstones are broad lens-shaped bodies; thicknesses range up to 30 ft with aspect ratios (width/thickness) of 100 to 10,000. Lobe sandstones may be interstratified with laminated siltstones.

  9. Fluvial-deltaic sedimentation and stratigraphy of the ferron sandstone

    USGS Publications Warehouse

    Anderson, P.B.; Chidsey, T.C.; Ryer, T.A.

    1997-01-01

    East-central Utah has world-class outcrops of dominantly fluvial-deltaic Turonian to Coniacian aged strata deposited in the Cretaceous foreland basin. The Ferron Sandstone Member of the Mancos Shale records the influences of both tidal and wave energy on fluvial-dominated deltas on the western margin of the Cretaceous western interior seaway. Revisions of the stratigraphy are proposed for the Ferron Sandstone. Facies representing a variety of environments of deposition are well exposed, including delta-front, strandline, marginal marine, and coastal-plain. Some of these facies are described in detail for use in petroleum reservoir characterization and include permeability structure.

  10. Tidal influence within Pennsylvanian sandstones

    SciTech Connect

    Archer, A.W. )

    1991-08-01

    Within Pennsylvanian-age strata of the Illinois basin, large-scale linear sand bodies have been previously interpreted as fluvial and deltaic in origin. Nonetheless, analyses of fine-scale sedimentology and bed forms within such sandstones and the associated shales indicate that tidal processes greatly influenced the depositional environments within such lithofacies. Recent work on Mid-Continent Pennsylvanian-age sandstones indicates the occurrence of similar depositional environments. Based upon the pervasive tidal influence observed within such strata, environmental analogs other than fluvial and deltaic bear consideration. In general, tidally influenced estuarine models seem particularly appropriate. Within such settings, the changeover from a fluvially dominated deposystem to tidally influenced estuary occurs during transgressive phases. Despite the tidal influence that can be interpreted from the sedimentology, the strata contain few, if any, marine indicators because of the low salinities that occurred during deposition. Ongoing work in the Mid-Continent indicates that Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian sands share a number of similarities with the tidally influenced environments delineated in the Illinois basin studies. Thus a tidal/estuarine interpretation might be a generalizable model for many Pennsylvanian sandstones. In addition, enhanced understanding of the siliciclastic parts of Mid-Continent cyclothems provides a more useful framework for documentation of carbonate/siliciclastic interrelationships. Oscillations of carbonate/siliciclastic environments may be more readily explainable by climatic cycles rather than by traditionally popular depth-related facies models.

  11. Geothermal and heavy-oil resources in Texas

    SciTech Connect

    Seni, S.J.; Walter, T.G.

    1994-01-01

    In a five-county area of South Texas, geopressured-geothermal reservoirs in the Paleocene-Eocene Wilcox Group lie below medium- to heavy-oil reservoirs in the Eocene Jackson Group. This fortuitous association suggests the use of geothermal fluids for thermally enhanced oil recovery (TEOR). Geothermal fairways are formed where thick deltaic sandstones are compartmentalized by growth faults. Wilcox geothermal reservoirs in South Texas are present at depths of 11,000 to 15,000 ft (3,350 to 4,570 m) in laterally continuous sandstones 100 to 200 ft (30 to 60 m) thick. Permeability is generally low (typically 1 md), porosity ranges from 12 to 24 percent, and temperature exceeds 250{degrees}F (121{degrees}C). Reservoirs containing medium (20{degrees} to 25{degrees} API gravity) to heavy (10{degrees} to 20{degrees} API gravity) oil are concentrated along the Texas Coastal Plain in the Jackson-Yegua Barrier/Strandplain (Mirando Trend), Cap Rock, and Piercement Salt Dome plays and in the East Texas Basin in Woodbine Fluvial/Deltaic Strandplain and Paluxy Fault Line plays. Injection of hot, moderately fresh to saline brines will improve oil recovery by lowering viscosity and decreasing residual oil saturation. Smectite clay matrix could swell and clog pore throats if injected waters have low salinity. The high temperature of injected fluids will collapse some of the interlayer clays, thus increasing porosity and permeability. Reservoir heterogeneity resulting from facies variation and diagenesis must be considered when siting production and injection wells within the heavy-oil reservoir. The ability of abandoned gas wells to produce sufficient volumes of hot water over the long term will also affect the economics of TEOR.

  12. Process regime variability across growth faults in the Paleogene Lower Wilcox Guadalupe Delta, South Texas Gulf Coast

    NASA Astrophysics Data System (ADS)

    Olariu, Mariana I.; Ambrose, William A.

    2016-07-01

    The Wilcox Group in Texas is a 3000 m thick unit of clastic sediments deposited along the Gulf of Mexico coast during early Paleogene. This study integrates core facies analysis with subsurface well-log correlation to document the sedimentology and stratigraphy of the Lower Wilcox Guadalupe Delta. Core descriptions indicate a transition from wave- and tidally-influenced to wave-dominated deposition. Upward-coarsening facies successions contain current ripples, organic matter, low trace fossil abundance and low diversity, which suggest deposition in a fluvial prodelta to delta front environment. Heterolithic stratification with lenticular, wavy and flaser bedding indicate tidal influence. Pervasively bioturbated sandy mudstones and muddy sandstones with Cruziana ichnofacies and structureless sandstones with Ophiomorpha record deposition in wave-influenced deltas. Tidal channels truncate delta front deposits and display gradational upward-fining facies successions with basal lags and sandy tabular cross-beds passing into heterolithic tidal flats and biologically homogenized mudstones. Growth faults within the lower Wilcox control expanded thickness of sedimentary units (up to 4 times) on the downdip sides of faults. Increased local accommodation due to fault subsidence favors a stronger wave regime on the outer shelf due to unrestricted fetch and water depth. As the shoreline advances during deltaic progradation, successively more sediment is deposited in the downthrown depocenters and reworked along shore by wave processes, resulting in a thick sedimentary unit characterized by repeated stacking of shoreface sequences. Thick and laterally continuous clean sandstone successions in the downthrown compartments represent attractive hydrocarbon reservoirs. As a consequence of the wave dominance and increased accommodation, thick (tens of meters) sandstone-bodies with increased homogeneity and vertical permeability within the stacked shoreface successions are created.

  13. Fluvial to Lacustrine Facies Transitions in Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Sumner, Dawn Y.; Williams, Rebecca M. E.; Schieber, Juergen; Palucis, Marisa C.; Oehler, Dorothy Z.; Mangold, Nicolas; Kah, Linda C.; Gupta, Sanjeev; Grotzinger, John P.; Grant, John A., III; Edgar, Lauren A.; Dietrich, William E.

    2015-01-01

    NASA's Curiosity rover has documented predominantly fluvial sedimentary rocks along its path from the landing site to the toe of the Peace Vallis alluvial fan (0.5 km to the east) and then along its 8 km traverse across Aeolis Palus to the base of Aeolis Mons (Mount Sharp). Lacustrine facies have been identified at the toe of the Peace Vallis fan and in the lowermost geological unit exposed on Aeolis Mons. These two depositional systems provide end members for martian fluvial/alluvial-lacustrine facies models. The Peace Vallis system consisted of an 80 square kilometers alluvial fan with decimeter-thick, laterally continuous fluvial sandstones with few sedimentary structures. The thin lacustrine unit associated with the fan is interpreted as deposited in a small lake associated with fan runoff. In contrast, fluvial facies exposed over most of Curiosity's traverse to Aeolis Mons consist of sandstones with common dune-scale cross stratification (including trough cross stratification), interbedded conglomerates, and rare paleochannels. Along the southwest portion of the traverse, sandstone facies include south-dipping meter-scale clinoforms that are interbedded with finer-grained mudstone facies, interpreted as lacustrine. Sedimentary structures in these deposits are consistent with deltaic deposits. Deltaic deposition is also suggested by the scale of fluvial to lacustrine facies transitions, which occur over greater than 100 m laterally and greater than 10 m vertically. The large scale of the transitions and the predicted thickness of lacustrine deposits based on orbital mapping require deposition in a substantial river-lake system over an extended interval of time. Thus, the lowermost, and oldest, sedimentary rocks in Gale Crater suggest the presence of substantial fluvial flow into a long-lived lake. In contrast, the Peace Vallis alluvial fan onlaps these older deposits and overlies a major unconformity. It is one of the youngest deposits in the crater, and

  14. Provenance of Norphlet sandstone, northern Gulf Coast

    SciTech Connect

    Ryan, W.P.; Ward, W.C.; Kuglar, R.L.

    1987-09-01

    The Upper Jurassic Norphlet sandstone of the northern Gulf Coast is predominantly subarkose, with some arkose in the eastern area and sublitharenite and quartzarenite in the western area. Despite great depths of burial and despite feldspar and rock-fragment constituents, diagenesis has not appreciably altered the composition of Norphlet sandstone. Therefore, reconstruction of original composition of Norphlet sandstone presented little difficulty. Variation in detrital modes of the Norphlet suggests compositionally distinct source terranes. Samples from Florida, Alabama, and Mississippi reflect the influence of metamorphic and plutonic rocks of the Appalachian Piedmont Province and of Triassic-Jurassic volcanic rocks. Sandstones in east Texas, northern Louisiana, and southern Arkansas were derived from sedimentary and metasedimentary rocks of the Ouachita system. The Arbuckle Mountains and Llano uplift may have supplied trace amounts of quartzo-feldspathic and volcanic-rock fragments to the extreme western part of the study area. Norphlet sandstones represent a mixture of collision-orogen-derived sediment from the Appalachian and/or Ouachita system and continental-block-derived sediment from paleohighs and uplifts within the Gulf basin. However, Norphlet sandstones plot in the craton-interior and transitional-continental fields on Q-F-L and QM-F-Lt tectonic-provenance diagrams, because of mineralogically mature source rocks, elimination of unstable grains by abrasion and sorting during deposition, and/or sediment mixing from different source terranes.

  15. Porosity prediction in sandstones using erosional unconformities

    SciTech Connect

    Shanmugam, G.

    1989-03-01

    Erosional unconformities of subaerial origin are created by tectonic uplifts and eustatic sea level fall. Most erosional unconformities developed on sandstones are planes of increased porosity because uplifted sandstones are exposed to undersaturated CO/sub 2/-charged meteoric waters that result in dissolution of unstable framework grains and cements. The chemical weathering of sandstones is intensified in humid regions by the heavy rainfall, soil zones, lush vegetation, and accompanying voluminous production of organic and inorganic acids. Erosional unconformities are considered hydrologically open systems because of abundant supply of fresh meteoric water and relatively unrestricted transport of dissolved constituents away from the site of dissolution, causing a net gain in porosity near unconformities. Thus, porosity in sandstones tends to increase toward overlying unconformities. Such porosity trends have been observed in hydrocarbon-bearing sandstone reservoirs in Alaska, Algeria, Australia, China, Libya, Netherlands, Norwegian North Sea, Norwegian Sea, and Texas. A common attribute of these reservoirs is that they were all subaerially exposed under heavy rainfall conditions. An empirical model has been developed for the Triassic and Jurassic sandstone reservoirs in the Norwegian North Sea on the basis of the observed relationship that shows an increase in porosity in these reservoirs with increasing proximity to the overlying base of Cretaceous unconformity. An important practical attribute of this model is that it allows for the prediction of porosity in the neighboring undrilled areas by recognizing the base of Cretaceous unconformity in seismic reflection profiles and by constructing subcrop maps.

  16. Shannon Sandstone in Wyoming: A shelf-ridge complex reinterpreted as lowstand shoreface deposits

    SciTech Connect

    Walker, R.G.; Bergman, K.M. . Dept. of Geology)

    1993-09-01

    The Shannon Sandstone (Campanian) of Wyoming was formerly interpreted as two stacked shelf-ridge complexes. Sand was believed to have been transported from a time-equivalent shoreline 110-150 km to the west and reworked or molded into ridges at the depositional site. The authors show that this time-equivalent shoreline section at Lucerne, Wyoming, consists of not one shoreface sandbody, but two superimposed. They are both storm-dominated, and the lower one terminates in beach facies capped by root traces. There must have been a rise in relative sea level of at least 14m to make accommodation space for the second shoreface sandbody. In the Slat Creek area and the adjacent subsurface Teapot Dome, there are two sandier-upward facies successions. In the lower succession there are abrupt vertical facies contacts between offshore bioturbated sandstones, thicker hummocky cross-stratified sandstones, and coarser cross-bedded sandstones. There is also evidence that the cross-bedded sandstones rest erosively on underlying facies. The trace fauna in the sandstones includes Macaronichnum segregatis, Rosselia socialis, and Ophiomorpha. The M. segregatis suggests a foreshore or upper-shoreface depositional environment, and R. socialis indicates a lower to middle shoreface; neither are characteristic of a shelf-ridge complex. The abrupt and probably erosive facies contacts, along with the trace fauna, suggest that the cross-bedded sandstones in this succession represent a shoreface deposit that formed during a stage of actively falling relative sea level. Overlying muddy bioturbated sandstones indicate that shoreface deposition was terminated by a transgression. The upper sandier-upward succession contains facies and trace fauna similar to those of the lower succession, and is also interpreted as a prograding shoreface.

  17. Sequence Stratigraphic Analysis and Facies Architecture of the Cretaceous Mancos Shale on and Near the Jicarilla Apache Indian Reservation, New Mexico-their relation to Sites of Oil Accumulation

    SciTech Connect

    Ridgley, Jennie

    2001-08-21

    The purpose of phase 1 and phase 2 of the Department of Energy funded project Analysis of oil- bearing Cretaceous Sandstone Hydrocarbon Reservoirs, exclusive of the Dakota Sandstone, on the Jicarilla Apache Indian Reservation, New Mexico was to define the facies of the oil producing units within the Mancos Shale and interpret the depositional environments of these facies within a sequence stratigraphic context. The focus of this report will center on (1) redefinition of the area and vertical extent of the ''Gallup sandstone'' or El Vado Sandstone Member of the Mancos Shale, (2) determination of the facies distribution within the ''Gallup sandstone'' and other oil-producing sandstones within the lower Mancos, placing these facies within the overall depositional history of the San Juan Basin, (3) application of the principals of sequence stratigraphy to the depositional units that comprise the Mancos Shale, and (4) evaluation of the structural features on the Reservation as they may control sites of oil accumulation.

  18. Gulf of Mexico Oil and Gas Atlas Series: Chronostratigraphically bound reservoir plays in Texas and federal offshore waters

    SciTech Connect

    Seni, S.J.; Desselle, B.A.; Standen, A.

    1994-09-01

    The search for additional hydrocarbons in the Gulf of Mexico is directing exploration toward both deep-water frontier trends and historically productive areas on the shelf. The University of Texas at Austin, Bureau of Economic Geology, in cooperation with the Minerals Management Service, the Gas Research Institute, and the U.S. Department of Energy, is responding to this need through a coordinated research effort to develop an oil and gas atlas series for the offshore northern Gulf of Mexico. The atlas series will group regional trends of oil and gas reservoirs into subregional plays and will display graphical location and reservoir data on a computerized information system. Play methodology includes constructing composite type logs with producing zones for all fields, identifying progradational, aggradational, and retrogradational depositional styles, and displaying geologic data for type fields. Deep-water sand-rich depositional systems are identified separately on the basis of faunal ecozones, chronostratigraphic facies position, and log patterns. To date, 4 Oligocene, 19 Lower Miocene, and 5 Upper Miocene plays have been identified in Texas state offshore waters. Texas state offshore plays are gas prone and are preferentially trapped in rollover anticlines. Lower Miocene plays include deep-water sandstones of Lenticulina hanseni and jeffersonensis; progradational sandstones of Marginulina, Discorbis b, Siphonia davisi, and Lenticulina; transgressive sandstones associated with a barrier-bar system in the Matagorda area; and transgressive sandstones below Amphistegina B shale. Particularly productive gas-prone plays are progradational Siphonia davisi, shelf-margin deltas in the High Island area, and progradational Marginulina shelf and deltaic sands in association with large rollover anticlines in the Matagorda Island and Brazos areas.

  19. Sedimentology and genetic stratigraphy of Dean and Spraberry Formations (Permian), Midland basin, Texas

    SciTech Connect

    Handford, C.R.

    1981-09-01

    The Spraberry trend of west Texas, once known as the world's largest uneconomic oil field, will undoubtedly become an increasingly important objective for the development of enhanced oil recovery techniques in fine-grained, low-permeability, low-pressure reservoirs. As the trend expands, facies and stratigraphic data should be integrated into exploration strategies. The Spraberry and Dean Formations may be divided into three genetic sequences, each consisting of several hundred feet of interbedded shale and carbonate overlain by a roughly equal amount of sandstone and siltstone. These sequences record episodes of shelf-margin progradation, deep-water resedimentation of shelf-derived carbonate debris, followed by influxes of terrigenous clastics into the basin by way of feeder channels or submarine canyons, and suspension settling of fine-grained sediment from the water column. Four lithofacies comprise the terrigenous clastics of the Spraberry and Dean Fomations: (1) cross-laminated, massive, and parallel-laminated sandstone, (2) laminated siltstone, (3) bioturbated siltstone, and (4) black, organic-rich shale. Carbonate lithofacies occur mostly in the form of thin-bedded turbidites, slump, and debris-flow deposits. Terrigenous clastic rocks display facies sequences, isopach patterns, and sedimentary structures suggestive of deposition from turbidity currents, and long-lived saline density underflow and interflow currents. Clastic isopach patterns reflect an overall southward thinning of clastics in the Midland basin. Channelized flow and suspension settling were responsible for the formation of elongate fan-shaped accumulations of clastic sediments.

  20. Sedimentology and reservoir characteristics of tight gas sandstones, Frontier formation, southwestern Wyoming

    SciTech Connect

    Moslow, T.F.; Tillman, R.W.

    1984-04-01

    The lower Frontier Formation, Moxa arch area, southwestern Wyoming, is one of the most prolific gas-producing formations in the Rocky Mountain region. Lowr Frontier sediments were deposited as strandplains and coalescing wave-dominated deltas that prograding into the western margin of the Cretaceous interior seaway during the Cenomanian. In this study, sedimentologic, petrologic, and stratigraphic analyses were conducted on cores and logs of Frontier wells from the Whiskey Buttes and Moxa fields. Twelve sedimentary facies have been identified. The most common sequence consists of burrowed to cross-bedded near shore marine (delta-front and inner-shelf) sandstones disconformably overlain by crossbedded (active) to deformed (abandoned) distributary-channel sandstones and conglomerates. The sequence is capped by delta-plain mudstones and silty sandstones. Tight-gas sandstone reservoir facies are nonhomogenous and include crevasse splay, abandoned and active distributary channel, shoreface, foreshore, and inner shelf sandstones. Distributary-channel facies represent 80% of perforated intervals in wells in the southern part of the Moxa area, but only 50% to the north. Channel sandstone bodies are occasionally stacked, occur on the same stratigraphic horizon, and are laterally discontinuous with numerous permeability barriers. Percentage of perforated intervals in upper shoreface and foreshore facies increases from 20% in the south to 50% in the north.

  1. Sedimentology and reservoir characteristics of tight gas sandstones, Frontier formation, southwestern Wyoming

    SciTech Connect

    Moslow, T.F.; Tillman, R.W.

    1984-04-01

    The lower Frontier Formation, Moxa arch area, southwestern Wyoming, is one of the most prolific gas-producing formations in the Rocky Mountain region. Lower Frontier sediments were deposited as strandplains and coalescing wave-dominated deltas that prograding into the western margin of the Cretaceous interior seaway during the Cenomanian. In this study, sedimentologic, petrologic, and stratigraphic analyses were conducted on cores and logs of Frontier wells from the Whiskey Buttes and Moxa fields. Twelve sedimentary facies have been identified. The most common sequence consists of burrowed to cross-bedded near shore marine (delta-front and inner-shelf) sandstones disconformably overlain by cross-bedded (active) to deformed (abandoned) distributary-channel sandstones and conglomerates. The sequence is capped by delta-plain mudstones and silty sandstones. Tight-gas sandstone reservoir facies are non-homogenous and include crevasse splay, abandoned and active distributary channel, shoreface, foreshore, and inner shelf sandstones. Distributary-channel facies represent 80% of perforated intervals in wells in the southern part of the Moxa area, but only 50% to the north. Channel sandstone bodies are occasionally stacked, occur on the same stratigraphic horizon, and are laterally discontinuous with numerous permeability barriers. Percentage of perforated intervals in upper shoreface and foreshore facies increases from 20% in the south to 50% in the north.

  2. Sedimentation of shelf sandstones in Queen Formation, McFarland and Means fields, central basin platform of Permian basin

    SciTech Connect

    Malicse, A.; Mazzullo, J.; Holley, C.; Mazzullo, S.J.

    1988-01-01

    The Queen Formation is a sequence of carbonates, evaporites, and sandstones of Permian (Guadalupian) age that is found across the subsurface of the Central Basin platform of the Permian basin. The formation is a major hydrocarbon reservoir in this region, and its primary reservoir facies are porous shelf sandstones and dolomites. Cores and well logs from McFarland and Means fields (on the northwest margin of the Central Basin platform) were examined to determine the sedimentary history of the shelf sandstones.

  3. Deep-marine facies models: Implications for hydrocarbon exploration and production

    SciTech Connect

    Shanmugam, G. )

    1991-03-01

    Facies models serve as a generalized conceptual framework for classifying and understanding sedimentary environments. Deep-marine facies models range in scale from a single facies of a turbidite bed (first-order models) to an association of different facies representing an entire submarine fan or a basin-fill complex (third-order models). At present, numerous facies models exist for modern and ancient deep-marine systems with distinct depositional components. These models are based on (1) types of channel (e.g., convergent and divergent channel systems, low-sinuosity and high-sinuosity channel patterns), (2) types of lobes (e.g., suprafan lobes, depositional lobes, fanlobes, ponded lobes), (3) tectonic settings (e.g., active-margin and mature passive-margin fans), (4) eustatic sea-level changes (e.g., lowstand submarine fans and highstand nonfan turbidites), (5) sediment sources (e.g., canyon-fed submarine fan and delta-fed submarine ramp), and (6) bottom-current reworking. It is also clear that not all submarine fans are composed of identical distribution of depositional facies in time and space. Therefore, no single facies model can adequately explain all submarine fans. Submarine fans can and do vary in their size, shape, lithofacies distribution, sand-body geometry, and reservoir quality. Because facies models differ significantly from each other in terms of reservoir properties, caution must be exercised in selecting a particular facies model for a sandstone reservoir.

  4. Sedimentary Petrography and Facies Analysis at the Shaler Outcrop, Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Edgar, L. A.; Gupta, S.; Rubin, D. M.; Lewis, K. W.; Kocurek, G.; Anderson, R. B.; Bell, J. F.; Dromart, G.; Edgett, K. S.; Grotzinger, J. P.; Hardgrove, C. J.; Kah, L. C.; Leveille, R. J.; Malin, M.; Mangold, N.; Milliken, R.; Minitti, M. E.; Rice, M. S.; Rowland, S. K.; Schieber, J.; Stack, K.; Sumner, D. Y.; Team, M.

    2013-12-01

    The Mars Science Laboratory Curiosity rover has recently completed an investigation of a large fluvial deposit known informally as the Shaler outcrop (~1 m thick). Curiosity acquired data at the Shaler outcrop during sols 120-121 and 309-324. The Shaler outcrop is comprised of cross-bedded coarse-grained sandstones and recessive finer-grained intervals. Shaler is distinguished from the surrounding units by the presence of resistant beds exhibiting decimeter scale trough cross-bedding. Observations using the Mast Cameras, Mars Hand Lens Imager (MAHLI) and ChemCam Remote Micro Imager (RMI) enable the recognition of several distinct facies. MAHLI images were acquired on five distinct rock targets, and RMI images were acquired at 33 different locations. On the basis of grain size, erosional resistance, color, and sedimentary structures, we identify four facies: 1) resistant cross-stratified facies, 2) smooth, fine-grained cross-stratified facies, 3) dark gray, pitted facies, and 4) recessive, vertically fractured facies. Panoramic Mastcam observations reveal facies distributions and associations, and show cross-bedded facies that are similar to those observed at the Rocknest and Bathurst_Inlet locations. MAHLI and RMI images are used to determine the grain size, sorting, rounding and sedimentary fabric of the different facies. High-resolution images also reveal small-scale diagenetic features and sedimentary structures that are used to reconstruct the depositional and diagenetic history.

  5. National Uranium Resource Evaluation: Palestine Quadrangle, Texas and Louisiana

    SciTech Connect

    McGowen, M.; Basciano, J.; Fose, F.G. Jr.; Fisher, W.L.

    1982-09-01

    The uranium resource potential of the Palestine Quadrangle, Texas and Louisiana, was evaluated to a depth of 1500 m (5000 ft) using criteria established for the National Uranium Resource Evaluation program. Data derived from geochemical analyses of surface samples (substrate, soil, and stream sediment) in conjunction with hydrochemical data from water wells were used to evaluate geologic environments as being favorable or unfavorable for the occurrence of uranium deposits. Two favorable environments have been identified in the Palestine Quadrangle: potential deposits of modified Texas roll-type in fluvial channels and associated facies within the Yegua Formation, and potential occurrences along mineralization fronts associated with the Elkhart Graben and Mount Enterprise fault system. Unfavorable environments include: Cretaceous shales and limestones, Tertiary fine-grained marine sequences, Tertiary sandstone units that exhibit favorable host-rock characteristics but fail to show significant syngenetic or epigenetic mineralization, and Quaternary sands and gravels. Unevaluated units include the Woodbine Group (Upper Cretaceous), Jackson Group (Tertiary), and Catahoula Formation (Tertiary). The subsurface interval of the Jackson Group and Catahoula Formation contains depositional facies that may represent favorable environments; however, the evaluation of these units is inconclusive because of the general lack of shallow subsurface control and core material. The Woodbine Group, restricted to the subsurface except for a small exposure over Palestine Dome, occurs above 1500 m (5000 ft) in the northwest quarter of the quadrangle. The unit exhibits favorable host-rock characteristics, but the paucity of gamma logs and cores, as well as the lack of hydrogeochemical and stream-sediment reconnaissance data, makes evaluation of the unit difficult.

  6. Sedimentology and cyclicity in the Lower Permian De Chelly sandstone on the Defiance Plateau: Eastern Arizona

    SciTech Connect

    Stanesco, J.D. )

    1991-10-01

    Lithofacies in the De Chelly Sandstone consist of (1) a large-scale trough to tabular- and/or wedge-planar cross-stratified sandstone facies of large-scale eolian dune origin, (2) a small- to medium-scale, trough cross-stratified sandstone also of eolian dune origin, (3) a horizontally stratified, wind-rippled sandstone of sand sheet origin, (4) a wavy, horizontally stratified, wind-rippled sandstone of sabkha origin, and (5) a mud-draped ripple-laminated sandstone of mud-flat origin. The De Chelly Sandstone in the northern Defiance Plateau consists mainly of large-scale dune deposits. Stratigraphic sections in the middle of the plateau are dominated by small- to medium-scale dune and sand sheet deposits whereas those along the southern end of the plateau are composed largely of sabkha and supratidal mud-flat deposits. The lateral distribution of these facies suggests a north-south juxtaposition of central-erg, fore-erg, and mixed sabkha-supratidal depositional environments. Repetitive interbedding of facies in the De Chelly indicates at least twelve depositional cycles in which sabkha and/or supratidal to coastal-plain mud-flats were sequentially overridden by eolian sand sheets and cross-stratified dunes. Lateral and vertical facies relations within the lower and upper members of the De Chelly Sandstone record episodic expansion of the De Chelly erg southward. The comparative abundance of large-scale dune deposits in the upper member suggests that progradation was more extensive during latter stages of deposition. The intervening tongue of Supai Formation and the redbeds that overlie the upper member of the De Chelly at Bonito Canyon document northward transgression of sabkha and supratidal to coastal-plain mud-flat environments. Eolian dune deposition was restricted to the northern Defiance Plateau during deposition of these units.

  7. Sedimentology of the fluvial and fluvio-marine facies of the Bahariya Formation (Early Cenomanian), Bahariya Oasis, Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Khalifa, M. A.; Catuneanu, O.

    2008-05-01

    The Lower Cenomanian Bahariya Formation in the Bahariya Oasis, Western Desert, Egypt, was deposited under two coeval environmental conditions. A fully fluvial system occurs in the southern portion of the Bahariya Oasis, including depositional products of meandering and braided streams, and a coeval fluvio-marine setting is dominant to the north. These deposits are organized into four unconformity-bounded depositional sequences, whose architecture is shaped by a complex system of incised valleys. The fluvial portion of the lower two depositional sequences is dominated by low-energy, meandering systems with a tabular geometry, dominated by overbank facies. The fluvial deposits of the upper two sequences represent the product of sedimentation within braided streams, and consist mainly of amalgamated channel-fills. The braided fluvial systems form the fill of incised valleys whose orientation follows a southeast-northwest trending direction, and which truncate the underlying sequences. Four sedimentary facies have been identified within the braided-channel systems, namely thin-laminated sandstones (Sh), cross-bedded sandstones (Sp, St), massive ferruginous sandstones (Sm) and variegated mudstones (Fm). The exposed off-channel overbank facies of the meandering systems include floodplain (Fm) and crevasse splay (Sl) facies. The fluvio-marine depositional systems consist of interbedded floodplain, coastal and shallow-marine deposits. The floodplain facies include fine-grained sandstones (Sf), laminated siltstones (Stf) and mudstones (Mf) that show fining-upward cycles. The coastal to shallow-marine facies consist primarily of mudstones (Mc) and glauconitic sandstones (Gc) organized vertically in coarsening-upward prograding cyclothems topped by thin crusts of ferricrete (Fc). The four depositional sequences are present across the Bahariya Oasis, albeit with varying degrees of preservation related to post-depositional erosion associated with the formation of sequence

  8. Frisco City sandstone: Upper Jurassic play in southern Alabama

    SciTech Connect

    Montgomery, S.L.; Baria, L.R.; Handford, C.R.

    1997-10-01

    The Frisco City sandstone play in southern Alabama is an example of hydrocarbon entrapment on the flanks of basement erosional features, with principal reservoirs occurring in proximal alluvial-fan to marine shoreface facies. Productive fields are developed on four-way closures of complex geometry, with reservoir sandstones showing maximum thickness along the margins of basement highs that are roughly 1.3-5.18 km{sup 2} in size and have 136-151 m of relief. Detailed analysis of sandstone facies indicates a downdip progression from alluvial-fan through wadi, eolian, beach, tidal-flat, and shoreface deposits. A sequence stratigraphic model based on identification of backstepping strata representing successive transgressive events is useful in predicting maximum reservoir occurrence in the vicinity of inselbergs. Reservoir quality in productive sandstones is high, with porosities ranging from 13 to 27% and permeabilities of 50 md to 5 d. Hydrocarbon occurrence is related to the distribution of high-quality source rock in the Smackover Formation and to maturation history.

  9. Reservoir characterization and preliminary modeling of deltaic facies, lower Wilcox, Concordia Parish, Louisiana

    SciTech Connect

    Schenewerk, P.; Goddard, D.; Echols, J.

    1994-12-31

    The decline in production in several fields in Concordia Parish, Louisiana, has created interest in the economic feasibility of producing the remaining bypassed oil in the lower Wilcox Group. One of these fields, Bee Brake, has been one of the more prolific oil-producing fields in east-central Louisiana. The producing interval, the Minter sandstones, at a depth of about 6,775 ft typically consists of an upper Bee Brake sandstone and a lower Angelina sandstone. A detailed study of a conventional core in the center of the field reveals a 15-ft-thick Minter interval bounded above and below by sealing shales and lignites of lower delta plain marsh facies. The upper 4-ft-thick Bee Brake is a very fine silty sandstone with characteristics of a small overbank or crevasse splay deposit. The lower 3-ft-thick oil-producing Angelina sandstone consists of very fine and fine sandstone of probable overbank or crevasse facies. Cumulative production from the Angelina is about 1.8 million stock-tank barrels of oil. Special core analysis data (capillary pressure, relative permeability, and waterflood recovery) have been used to develop a simulation model of the two reservoirs in the Minter. This model incorporates the geologic and engineering complexities noted during evaluation of the field area. Operators can use the model results in this field to design an optimal development plan for enhanced recovery.

  10. Upper Strawn (Desmoinesian) carbonte and clastic depositional environments, southeastern King County, Texas

    SciTech Connect

    Boring, T.H. )

    1990-02-01

    The Pennsylvanian upper Strawn Group of southeastern King County, Texas, provides a unique setting to study interactions between coeval carbonate and clastic deposition during the Desmoinesian. One of the most perplexing problems is the relationship of massive Pennsylvanian platform carbonates to shallow-water terrigenous clastic sediments. Within the study area, carbonate facies were deposited along the northern edge of the Knox-Baylor trough on the Spur platform, and terrigenous clastics were carried toward the Midland basin through the Knox-Baylor trough. Based on the analysis of subsurface cores, five carbonate lithofacies and four clastic lithofacies were recognized in southeastern King County, Texas. The distribution and geometry of these lithofacies are related to variations in the rate of subsidence in the Knox-Baylor trough, Pennsylvanian tectonics, deltaic progradation, avulsion, and compaction. The platform carbonates within the northern region of southeastern King County record environments within the carbonate platform complex, including middle platform, outer platform, algal mound, and platform margin. The quartzarenitic sandstones within the southern region of southeastern King County occur in a variety of complex depositional geometries, including distributary-bar fingers, lobate deltas, and offshore bars. Cores of these sandstones represent mainly the uppermost portion of the various sandstone bodies. The upper Strawn Group provides an attractive area for exploration geology. Both carbonates and clastics provide excellent reservoirs from a depth of approximately 5,000-6,000 ft. Total production within the area is over 100 million bbl of oil since the early 1940s. Multiple pay zones within a 600-ft interval also provide an added incentive for exploration. Areas within and around the Knox-Baylor trough deserve a detailed study due to these relatively shallow, unexplored, multiple pay zones.

  11. Provenance of Middle Tertiary sandstones of the San Emigdio and Tehachapi Mountains, southern California

    SciTech Connect

    Rhoades, M.L. . Geosciences Dept.)

    1992-01-01

    Petrographic analysis of 78 medium to coarse-grained sandstones collected from complete depositional sequences of early Eocene to early miocene age exposed in the San Emigdio and Tehachapi Ranges reveal moderately sorted, subangular arkoses and lithic arkoses. Framework sand-sized grains are primarily detrital quartz, potassium feldspar, plagioclase and lithic fragments. Lithic fragments consist of: (a) Volcanic/meta-volcanic types, (Lv); (b) low/high grade metamorphic types, (Lm); and, (c) sedimentary/meta-sedimentary types, (Ls). Gazzi-Dickinson point-counts of 450 framework grains per slide yield the following modal averages: Tejon Fm-Uvas Member: %QFL = 62, 34, 4; Metralla Member: %QFL = 43, 50, 7; San Emigdio Fm-Basal Member: %QFL = 49, 38, 13; Upper Sandstone Member: %QFL = 59, 34, 7; Tecuya Fm: %QFL = 62, 28, 10; Pleito: %QFL = 43, 49, 8; and, Temblor Fm: %QFL = 47, 46, 6. Modal data plotted on provenance discrimination diagrams indicate a continental block-uplifted basement provenance and a dissected arc provenance suggesting Sierran and Mojavian block sources. To determine the extent that depostional processes control sandstone composition, QFL averages and standard deviations were calculated for samples grouped by facies. Modal averages were distinct between facies: Fluvial, %QFL = 40, 47, 13; eolian, %QFL = 80, 16, 4; beach, %QFL = 75, 13, 12; surf zone-longshore trough, %QFL = 51, 41, 8; shelf, %QFL = 41, 46, 13. In general eolian and beach sandstones are more mature than fluvial, surf zone and shelf sandstones. Climate during deposition of the sandstones was not a dominant factor controlling sandstone composition. However, sandstone deposition during the tropical conditions of the Eocene produced predominantly quartose sandstones. Sandstones deposited after the Eocene/Oligocene climatic deterioration produced predominantly feldspar-rich sandstones.

  12. Regional distribution of wave- and fluvial-dominated deltaic deposits of Olmos formation (upper Cretaceous) in Maverick basin, southwest Texas

    SciTech Connect

    Ambrose, W.; Tyler, N.

    1984-04-01

    Regional subsurface analysis in southwest Texas indicates that the Olmos Formation (Gulfian) was deposited by a complex of wave- and fluvial-dominated delta systems in two depocenters. Sediment influx was from the north and northwest. Five deltaic submits, A through E, were deposited in the western depocenter. Three other deltaic wedges (F, G, H) formed the second depocenter farther east in present-day Frio and LaSalle Counties. Subsidence was greater in the western half of the Maverick basin where thickest (1,300 ft; 395 m) deltaic sediments were deposited. Lower Olmos strata represent a succession from wave-reworked, strike-elongate deltas of subunit A, similar to those of the underlying San Miguel Formation, to fluvial-dominated, dip-elongate deltas of subunits B and C. Extensive (1200 mi/sup 2/ or 3100 km/sup 2/ in Texas) aggradational floodplain deposits of B and C are characterized by diverse electric-log patterns; variation in log character is a response to complex depositional facies on the delta platform. Downdip, toward the Cretaceous shelf edge, delta-plain facies merge with upward-coarsening delta-front sandstones. Uppermost subunits D and E were deposited by a prograding barrier-island system in an interdeltaic embayment marginal to high constructive deltas of the easter depocenter. Lagoonal and fluvial-channel deposits are recognized from cores. Eastward migration of deposition was accompanied by an abrupt change of depositional style in the western depocenter from deltaic to coastal-interdeltaic.

  13. Organic facies characteristics of the Pliocene coaly units, central Anatolia, Ilgin (Konya / Turkey)

    NASA Astrophysics Data System (ADS)

    Altunsoy, Mehmet; Ozdoğan, Meltem; Ozcelik, Orhan; Ünal, Neslihan

    2015-04-01

    This study aims to determine organic facies characteristics of the Pliocene coaly units in the Ilgın (Konya, Central Anatolia, Turkey) area. Pliocene units (Dursunlu Formation) are composed of sandstone, siltstone, marl, mudstone and coal in the region. Lignite layers where coals are found and has a varying thickness between 100 - 300 m. Organic matter is composed predominantly of terrestrial material, with a minor contribution of algal and amorphous material. Organic matter in these units have generally low hydrogen index (HI) values and high oxygen index (OI) values, mostly characteristics type III kerogen (partly type II kerogen). Organic matters in the samples are immature to marginally mature in terms of organic maturation. Total organic carbon (TOC) values are generally between 0.03 and 51.7 %, but reach 53.4 % in the formation. Tmax values vary between 392 and 433 °C. Organic facies type C, CD and D were identified in the investigated units. C, CD and D facies are related to marl, mudstone and coal lithofacies. These facies are characterized by average values of HI around 102 (equivalent to type II/ III kerogene), TOC around 12.2 %, and an average of S2 of 14.6 mg HC/g of rock. The organic matter is terrestrial, partly oxidized / oxidized / highly oxidized , decomposed and reworked. Organic facies C and CD are the "gas-prone" facies but Organic facies D is nongenerative. Keywords: Central Anatolia, Pliocene, Organic Facies, Ilgın, Coal

  14. Petrology and reservoir paragenesis in the Sussex B sandstone of the Upper Cretaceous Cody Shale, House Creek and Porcupine fields, Powder River basin, Wyoming

    SciTech Connect

    Not Available

    1992-01-01

    This book of reservoir paragenesis includes detailed descriptions of the petrology of depositional facies of the Sussex B sandstone of the Sussex Sandstone Member of the Upper Cretaceous Cody Shale in the House Creek and Porcupine fields, Powder River basin, Wyoming.

  15. Effect of kaolinite as a key factor controlling the petrophysical properties of the Nubia sandstone in central Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Kassab, Mohamed A.; Abu Hashish, Mohamed F.; Nabawy, Bassem S.; Elnaggar, Osama M.

    2017-01-01

    This paper presents the results of a comprehensive petrographical and petrophysical investigation for the Late Cretaceous Nubia sandstone from Wadi Kareem in central Eastern Desert to measure their fluid flow properties and to investigate the effect of kaolinite on their petrophysical characteristics. From the petrographical analyses, scanning electron microscope 'SEM' and the X-ray diffraction 'XRD' analysis, it is shown that the studied sandstone samples are quite homogeneous in mineralogy and can be distinguished into four sedimentary microfacies: quartz arenite as a clean sandstone as well as three kaolinitic microfacies; namely they are kaolinitic quartz arenite, kaolinitic subarkose, and calcareous to kaolinitc quartz arenite. The main recognized diagenetic processes that prevailed during the post-depositional history of the Nubia sandstone are; compaction, cementation, alteration and dissolution of feldspar into kaolinite. The petrophysical potentiality of the studied sandstones was studied using the helium pycnometer, gas permeability and mercury injection confining pressure 'MICP' techniques. The investigated sandstones can be classified into three petrophysical facies with varying reservoir performances. The petrophysical behaviour of these facies is dependent mostly on their kaolinite content and its impact on porosity, permeability, irreducible water saturation, R35 (pore aperture corresponding to mercury saturation of 35% pore volume), R50 (median pore-throat radius), and MHR (the mean hydraulic radius). Therefore, the studied petrophysical facies are comparable to the distinguished petrographical facies.

  16. Carbonate facies and Landsat imagery of shelf off Belize, central America

    SciTech Connect

    Jordan, C.F. Jr.; Pusey, W.C. III; Belcher, R.C.; Borger, R.L.

    1985-02-01

    A reevaluation of Holocene sediments on the Belize shelf is based on (1) a newly constructed composite of 7 Landsat images, enhanced and registered to form a regional base map, and (2) a Holocene facies map based on a rigorous treatment of compositional and textural parameters for approximately 600 bottom samples. The sediments are mapped in terms usually applied to lithified carbonate rocks, allowing direct comparisons with carbonate facies in the subsurface. By combining Landsat imagery with this facies map, it is possible to point out the following geologic features: (1) major tectonic elements, such as the Maya Mountains, the Yucatan Plateau, several offshore bridges, and 3 large atolls, (2) major physiographic features such as the Belize barrier reef with its reef platform and crest, middle-shelf shoal deposits, middle-shelf patch reefs (including lagoon reefs or rhomboid reefs), (3) Holocene facies patterns with potential reservoir facies of foraminifera-grainstone bars, Halimeda grainstones, and branching-coral, encrusting red-algae boundstones, and (4) nearshore clastics and a sharp transition eastward to carbonate sediments. An understanding of Holocene facies patterns on the Belize shelf is important to the explorationist, because these facies patterns are living examples of exploration fairways and invite comparisons with several petroleum provinces: (1) Cretaceous reefs of Texas, (2) upper Paleozoic skeletal-grainstone bars in west Texas, and (3) Devonian reefs of the Alberta basin.

  17. Trace fossils and bioturbation in peritidal facies of the Potsdam-Theresa Formations (Cambrian-Ordovician), Northwest Adirondacks

    SciTech Connect

    Bjerstedt, T.W. ); Erickson, J.M. )

    1989-06-01

    The Cambrian-Ordovician Potsdam Sandstone, Theresa Formation, and Canadian correlatives in the St. Lawrence Lowlands preserve tide-dominated facies during the basal Cambrian transgression. Low intertidal sand flats in the upper Potsdam contain a Skolithos Ichnofacies dominated by Diplocraterion parallelum in clean, herringbone cross-bedded sandstones indicative of high tidal current energy. Wind-wave-driven longshore and tidal currents along a macrotidal coastline were funneled northeast-southwest by Precambrian topographic relief of up to 65 m. This relief is now expressed as the Thousand Islands of New York and Canada. The conformably overlying Theresa Formation preserves a shoaling-upward sequence of mixed clastic-carbonate facies. Shallow subtidal and peritidal facies contain a mixed Skolithos-Cruziana Ichnofacies in sharply alternating lithofacies consisting of gray, intensely bioturbated, poorly sorted calcareous sandstone, and meter-thick, white cross-bedded sandstone. The parallelism between ichnofacies and lithofacies indicates that environmental energy level and persistence rather than water depth controlled trace fossil distribution. Bioturbated sandstones contain a Cruziana ichnofacies of abundant deposit feeders including: Fustiglyphus , Gyrochorte , Neonereites uniserialis , Phycodes flabellum, Planolites beverlyensis, Rosselia socialis, and Teichichnus. Suspension feeders are represented by D. habichi, D. parallelum, Skolithos, Monocraterion, and possibly Palaeophycus tubularis. Scavenging or deposit-feeding arthropods are represented by rare Cruziana furrows. Cross-bedded sandstones contain a Skolithos Ichnofacies of shallow Skolithos and Monocraterion burrows, and an undescribed large epistratal eurypterid( ) trail.

  18. Volcanic Facies of the Lower Jurassic Talkeetna Formation, Iniskin Peninsula to Tuxedni Bay, Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Bull, K. F.

    2015-12-01

    The Lower Jurassic Talkeetna Formation (Jtk), a >1,000-km-long belt of vol­canic facies within the accreted intra-oceanic Talkeetna Arc has been characterized within the Talkeetna Mountains, but on the Alaska Peninsula Jtk facies have not previously been described in detail. Here we describe facies of the Jtk stretching from the Iniskin Peninsula to Tuxedni Bay. On the Iniskin Peninsula, a high concentration and great thickness of mafic to intermediate lavas, associated autobreccias and hyaloclastites, fluidal-clast breccias and possible pillows are suggestive of one or more submarine effusive eruption centers. Also volumetrically significant are non-stratified polymictic volcaniclastic breccia facies. Minor facies include thinly bedded volcaniclastic sandstone to pebble breccia-conglomerate facies, some of which are shard- and pumice-bearing pyroclastic deposits preserved in thinly bedded deposits, indicative of episodes of explosive volcanism and the eruption-fed nature of some of the deposits. North of Chinitna Bay, coherent facies tend to be thin and relatively small in volume. Volcaniclastic facies provide evidence of subaerial-fluvial deposition, and pyroclastic activity. Thinly bedded, laterally continuous beds locally exhibit cross-laminations, channel fills, normal grading and lenticular beds, and contain plant fossils. Within this sequence is a 10-m-thick pumice breccia containing fossilized logs, underlain by a thin, weakly laminated, pumice- and lithic-bearing volcaniclastic siltstone to sandstone. The log-bearing pumice breccia and the lithic-bearing laminated basal unit represent pyroclastic density current (PDC) facies deposited in a subaerial or possibly shallow aqueous environment. Underlying the PDC deposit are several 30-cm-thick maroon and olive green volcaniclastic fine-grained sandstone and siltstone beds containing channel fills, cross-beds and lenticular beds. Marbles exposed in the contact zone between the intrusions of Alaska

  19. Internal-tide deposits in an Ordovician submarine channel: Previously unrecognized facies

    SciTech Connect

    Gao Zhenzhong; Eriksson, K.A. )

    1991-07-01

    A Middle Ordovician submarine-channel deposit in the southern Appalachians is capped by an interval of fine-grained, predominantly cross-laminated sandstones that are interpreted as internal-tide deposits. Two facies are recognized: (1) bidirectional cross-laminated, very fine grained sandstones, and (2) unidirectional cross-bedded and cross-laminated, medium- to fine-grained sandstones. Facies 1 is dominated by bidirectional cross-laminations that dip both landward and seaward parallel to the paleochannel axis. This facies is related to up-channel and down-channel currents caused by internal tides. Facies 2 has both low-angle, tabular cross-beds and cross-laminations that dip landward. The formative up-channel currents are attributed to superimposition of internal waves on internal tides. The vertical transition from high-concentration gravity-flow deposits to intercalated low-concentration turbidites and internal-tide deposits is related to a rise in sea level that resulted in storage of coarse debris landward of the submarine channel.

  20. Sedimentology and cyclicity in the Lower Permian De Chelly Sandstone on the Defiance Plateau: eastern Arizona

    USGS Publications Warehouse

    Stanesco, J.D.

    1991-01-01

    The Lower Permian (Leonardian) De Chelly Sandstone crops out along a north-south trend on the Defiance Plateau of eastern Arizona. It is divided into lower and upper members separated by a tongue of the Supai Formation that pinches out to the north. Stratigraphy, and lateral and vertical facies relations within the lower and upper members, are discussed. -from Author

  1. Facies architecture and depositional environments of the Upper Cretaceous Kaiparowits Formation, southern Utah

    NASA Astrophysics Data System (ADS)

    Roberts, Eric M.

    2007-04-01

    The Kaiparowits Formation is an unusually thick package of Upper Cretaceous (late Campanian) strata exposed in Grand Staircase-Escalante National Monument of southern Utah, USA. The formation was deposited within the rapidly subsiding Cordilleran foreland basin as part of a thick clastic wedge derived from sources in the Sevier orogenic belt, thrust sheets in southeastern Nevada and southern California, and the Mogollon slope in southwestern Arizona. Channel systems in the Kaiparowits Formation shifted from northeastward to southeastward flow over time, and for a short period of time, sea level rise in the Western Interior Seaway resulted in tidally influenced rivers and/or estuarine systems. Thick floodbasin pond deposits, large suspended-load channels, and poorly developed, hydromorphic paleosols dominate the sedimentary record, and all are suggestive of a relatively wet, subhumid alluvial system. This is supported by extremely rapid sediment accumulation rates (41 cm/ka), and high diversity and abundance of aquatic vertebrate and invertebrate fossils. Facies and architectural analysis was performed on the Kaiparowits Formation, resulting in the identification of nine distinct facies associations: 1) intraformational conglomerate, 2) mollusc-shell conglomerate, 3) major tabular sandstone, 4) major lenticular sandstone, 5) minor tabular and lenticular sandstone, 6) finely laminated, calcareous siltstone, 7) inclined heterolithic sandstone and mudstone, 8) sandy mudstone, and 9) carbonaceous mudstone. These facies associations are interpreted as: 1) channel lags, 2) rare channel-hosted storm beds, 3) meandering channels, 4) anastomosing channels, 5) crevasse splays and crevasse channels, 6) lakes, 7) tidally influenced fluvial and/or estuarine channels, 8) mud-dominated floodplains, and 9) swamps and oxbow lakes. Based on this analysis, the formation is subdivided into three informal units, representative of gross changes in alluvial architecture, including facies

  2. Sand and sandstone

    SciTech Connect

    Pettijohn, F.J.; Potter, P.E.; Siever, R.

    1987-01-01

    Here is a new, second edition of a classical textbook in sedimentology, petrology, and petrography of sand and sandstones. It has been extensively revised and updated, including: new techniques and their utility; new literature; new illustrations; new, explicitly stated problems for the student; and a wider scope.

  3. Fault-related Silurian Clinton sandstone deposition in Ohio

    SciTech Connect

    Coogan, A.H. )

    1988-08-01

    Mapping the thickness of the Silurian Clinton sandstone reservoir and associated shale, sandstone, and carbonate facies in the subsurface of 40 counties in eastern Ohio reveals a general correspondence between major patterns of deposition and the location of faults that strike parallel with or subparallel to the depositional trends. Clinton delta-front sandstones, which occur along a line from Hocking and Perry Counties, through Knox, Holmes, and Wayne Counties northeast to Lake County, Ohio, parallel a line of major change in magnetic intensity in the basement, which is interpreted here to be the juncture between the more stable, less subsiding central Ohio carbonate bank and the more subsiding western edge of the Appalachian basin. The principal Clinton deltaic lobes occur in east-central and northeastern Ohio. The Clinton sandstone interval is thinner and starved of coarse clastic sediment close to the Rome trough, which is located along the southeasternmost Ohio border. Sediment distribution patterns indicate that deltaic deposits of Clinton sandstone were captured in the subsiding Rome trough at the border of southern Ohio during the Early Silurian. Farther north, deltaic sediments spread out across eastern Ohio to reach an elongate depocenter caused by minor subsidence at the central Ohio platform edge. There, deltaic sands intermittently filled the delta-edge trough, and spilled out as thin shelf sands onto the more stable platform, a site of predominantly mixed shale and carbonate deposition during the Early Silurian.

  4. Architecture of a transgressive systems tract: Tocito sandstone, New Mexico

    SciTech Connect

    Nummedal, D.; Swift, D.J.P.; Kofron, B.

    1988-02-01

    A sequence boundary is identified at the erosional base of the seaward units of the Tocito Sandstone by (1) a hiatus spanning three Inoceramus faunal zones, (2) basal onlap in the sequence above the hiatus as mapped in a pattern of progressively farther landward extent of younger bentonites, and (3) abrupt shallowing of facies across the hiatus. Traced up the depositional dip, the sequence boundary continues beneath a coarse fluvial sandstone (Torrivio sandstone) as demonstrated by incision of this unit into an underlying strand plain, the Gallup Sandstone. Individual Tocito sand bodies climb successively higher in the stratigraphic section when traced updip. Underlying these inferred shelf sand ridges is a landward-thickening wedge of fluvial strata (Dilco Coal Member of the Crevasse Canyon Formation), the expected consequence of trapping of siliciclastics on the transgressive coastal plain. The retrogradational deposits (Borrego Pass sandstone) constitute parasequences within the overall transgressive systems tract of the Tocito depositional sequence. The Tocito sand bodies are underlain by a stair-stepping set of ravinement surfaces, cut during episodes of shoreface retreat. They are overlain by parasequence condensed sections which appear to merge seaward into a major regional condensed section within the calcareous lower part of the Mulatto shale member of the upper Mancos Shale.

  5. Organic facies characteristics of the Carboniferous Pamucakyayla Formation, western Taurus, Antalya Nappes, Kemer (Antalya/Turkey)

    NASA Astrophysics Data System (ADS)

    Bertan Gulludag, Cevdet; Altunsoy, Mehmet; Ozcelik, Orhan

    2015-04-01

    The study area is located in the western part of the Taurus Belt (SW Turkey). This region exhibits a complex structure involving two autochthonous units surrounded and imbricated with three allochthonous complexes. Antalya Nappes is a complex tectonic imbricate structure including sedimantary and ultrabasic rocks. In this study, organic facies characteristics of Carboniferous coaly units in the Pamucakyayla region (Kemer, Antalya-Turkey) were examined. The Carboniferous Pamucakyayla Formation, which is characterized by sandstone, claystone, marl and coaly units. This units includes different levels of coal seams in different thicknesses. Organic matter is composed predominantly of woody and amorphous material, with a minor contribution of planty and coaly material. Kerogen in the deposits is type II/III, as indicated by organic petrographic observations and Rock-Eval data. Total organic carbon (TOC) values are generally between 0.01 and 1.44 %, but reach 5.81 % in the formation. Tmax values vary between 446 and 451 °C and indicate mature zone (Based on the value of 0.25 % TOC). Organic facies type BC, C and CD were identified in the investigated units. Organic facies BC is related sandstoneand marl lithofacies. This facis is deposited under an anoxic water column in a fine grained clastics, where rapid deposition creates anoxia in the sediments after deposition. This facies is characterized by average values of HI around 317 (equivalent to type II kerogene), TOC around 0.02 %, and an average of S2 of 0.04 mg HC/g of rock. Organic facies C is related to sandstone, marl and coal lithofacies. This facies is characterized by average values of HI around 176 (equivalent to type III kerogene), TOC around 0.19 %, and an average of S2 of 0.03 mg HC/g of rock. The organic matter is partly oxidized, and terrestrial. Organic facies C is the "gas-prone" facies. Organic facies CD is related to limestone, marl and coal lithofacies. This facies is characterized by average values

  6. The complex facies architecture and emplacement sequence of a Miocene submarine mega-pillow lava flow system, Muriwai, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Bear, A. N.; Cas, R. A. F.

    2007-02-01

    The early Miocene Waiatarua Formation at Maori Bay, Muriwai, North Island, New Zealand consists of a complex association of basaltic andesite volcanic facies including entablature-jointed thick massive facies, colonnade-jointed thin massive sheet facies, mega-pillow facies, normal pillow facies and minor associated fragmental facies, including vitric sandstone and breccia interpreted as hyaloclastite and peperite. Field observations suggest that the facies, which form the Waiatarua Formation lava, were emplaced as multiple flow lobes in a single lava flow from one sustained eruption. Magma discharge rate at the vent was high; however magma supply rate to the more distal and lateral portions of the flow, as its surface area increased, varied considerably. Higher magma supply rates produced thick, massive and thin sheet facies, whereas mega-pillow facies and normal pillow facies were produced contemporaneously with the thick and thin massive sheet facies but were restricted to portions of the distal flow subjected to lower magma supply rates. The evolution of the Waiatarua formation lava flow at Maori Bay has been reconstructed from the complex facies architecture. This suggests that the propagation of the lava involved 7 discrete lobes that were emplaced successively.

  7. Eustatic and salt-tectonic controls on sequence development, northern east Texas basin

    SciTech Connect

    Demarest, J.M. II; Ehman, K.D. )

    1990-05-01

    Detailed log and seismic interpretation of the Woodbine/Eagle Ford interval in the vicinity of the Hainesville dome of east Texas resulted in the recognition of salt-tectonic and eustatic controls on depositional patterns. Major cycles of transgression and regression within this interval correspond to eustatic cycles recognized worldwide. The late Cenomanian lowstand resulted in the deposition of fluvial Woodbine sandstones above the marine Maness Shale (93 Ma). Transgressive and highstand marine shales of the Eagle Ford rest above the fluvial Woodbine sands. A late Turonian sequence boundary (90 Ma) separates the highstand shales of the Eagle Ford from the lowstand and transgressive marine sands and shales of the sub-Clarksville. The section is capped by the transgressive Austin Chalk. Between the Woodbine (93 Ma) and the sub-Clarksville (90 Ma), the Hainesville salt dome evolved from a nonpiercement to a piercement salt dome. This evolution of the Hainesville dome caused the area adjacent to the present-day dome to change from a structural high to a rapidly subsiding basin adjacent to the dome. With the rapid loss of salt into the piercement dome around 92 Ma, conditions adjacent to the dome changed from subaerial onlapping of the Woodbine fluvial facies to distal downlapping of the Eagle Ford marine shales into the center of the Hainesville withdrawal syncline. Thus, the detailed timing of salt movement is recorded in the thickness and facies distribution around the salt dome within the context of major global eustatic cycles.

  8. Characteristics of deltaic deposits in the Cretaceous Pierre Shale, Trinidad Sandstone, and Vermejo Formation, Raton Basin, Colorado.

    USGS Publications Warehouse

    Flores, R.M.; Tur, S.M.

    1982-01-01

    Detailed facies analyses of closely spaced measured surface sections in the Trinidad and adjacent areas of Colorado reflect deposition in the river-influenced delta. That this deltaic system was accompanied by abandonment of subdeltas is indicated by a destructional-deltaic facies of heavily bioturbated, carbonaceous sandstones, siltstones, and shales best recorded in the delta front deposits of the Trinidad Sandstone. Coal accumulation of the Vermejo deposits nevertheless remained primarily controlled by persistent organic sedimentation in interdistributary backswamps. These backswamps, which accumulated thick, lenticular coals, were formed during the normal constructional phase of the delta plain. -from Authors

  9. Models for Facies and Compositional Variations in Gale Crater lake sediments, Mars

    NASA Astrophysics Data System (ADS)

    Grotzinger, J. P.

    2016-12-01

    The Murray formation, Gale crater, Mars contains one major depositional facies - laminated mudstone - deposited in a lake; and minor additional facies - ripple cross laminated and trough cross bedded sandstones - representing subaqueous delta foreslope, fluvial, or eolian environments. The persistence of fine lamination, locally with scour and drape truncation surfaces, and absence of desiccation cracks, prism cracks, intraclasts, displacive evaporite crystals and nodules all suggest a perennial lake formed at depths great enough to avoid seasonal desiccation. Possible eolian and fluvial deposits would indicate base level lowering during longer-term lake level oscillation. Two compositional facies are observed based on elemental and mineralogic data, a hematite-sulfate (HS) facies and magnetite-silica (MS) facies. The HS facies comprises the lower few meters of stratigraphy exposed in the foothills of Mt Sharp, and transitions upward without any major change in the physical facies into the MS facies which persists through 10 meters up to higher levels in the Murray formation. Thinning of lamination from 2 mm to 0.5 mm coincides with the compositional facies transition. At the highest stratigraphic levels studied by Curiosity hematitic rocks are encountered again but lack significant sulfates that are not associated with later diagenesis; physical facies are a mixture of finely laminated mudstones and trough crossbedded fine sandstones. Two models best fit the physical and compositional data. In the first case, variations in the composition of fine clastic detritus delivered to the lake via marginal sediment plumes, coupled with redox oscillations in the composition of authigenic minerals precipitated from the lake. In the second model, originally reduced sediments of either detrital or authigenic origin are oxidized during burial diagenesis related to circulation of oxidizing groundwaters, converting reduced species, e.g. magnetite and sulfides, to hematite and Fe

  10. Saline-water resources of Texas

    USGS Publications Warehouse

    Winslow, Allen George; Kister, Lester Ray

    1956-01-01

    Most of the aquifers in Texas contain saline water in some parts, and a few are capable of producing large quantities of saline water. Of the early Paleozoic formations, the Hickory sandstone member of the Riley formation of Cambrian age and the Ellenburger group of Ordovician age are potential sources of small to moderate supplies of saline water in parts of central and west-central Texas.

  11. Groundwater flow, late cementation, and petroleum accumulation the Permian Lyons Sandstone, Denver basin

    SciTech Connect

    Lee, M.K.; Bethke, C.M. )

    1994-02-01

    The gray diagenetic facies of the Permian Lyons Sandstone, associated with all known petroleum accumulations in the formation, formed late in the history of the Denver basin as an alteration product of the formation's red facies. The red facies that makes up most of the sandstone contains iron oxide coating, quartz overgrowths and calcite cements. The gray facies, which occurs locally in the deep basin, is distinguished by pore-filling dolomite and anhydrite cements and by a lack of iron oxide and calcite. The dolomite and anhydrite cements overlie bitumen that was deposited by migrating oil, and hence formed after oil was first generated in the basin, late in the Cretaceous or early in the Tertiary. The isotopic composition of oxygen in the dolomite ranges to such light values that the cement must have formed deep in the basin in the presence of meteoric water. The gray facies likely formed in a regime of groundwater flow resulting from Laramide uplift of the Front Range during the Tertiary. In our model, saline groundwater flowed eastward through the Pennsylvanian Fountain Formation and then upwelled along the basin axis, where is discharged into the Lyons Sandstone. The saline water mixed with more dilute groundwater in the Lyons, driving a reaction that dissolved calcite and, by a common-ion effect, precipitated dolomite and anhydrite. The facies' gray color resulted from reduction of ferric oxide in the presence of migrating oil or the Fountain brine. Underlying source beds by this time had begun to generate petroleum, which migrated by buoyancy into the Lyons. The association of the gray facies with petroleum accumulations can be explained if the Fountain brines discharged across aquitards along the same fractures that transmitted oil. As petroleum accumulated in the Lyons, the newly formed cements prevented continued migration, as is observed in shallower strata, by sealing oil into the reservoirs from which it is produced today. 77 refs., 16 figs., 5 tabs.

  12. Sedimentary facies analysis, El Dorado Field, Kansas, micellar chemical pilot project

    SciTech Connect

    Tillman, R.W.; Jordan, D.W.

    1981-05-01

    The Permian 650-ft sand, one of several productive sands in the El Dorado Field, has yielded 36.5 million bbl by primary and secondary methods, with 71 million bbl remaining. During initial stages of the micellar-polymer tertiary recovery pilot project drilling in 1974, a phase I geologic analysis, using 7 cores, identified distributary channels and associated smaller splay channels as productive facies. The western edge of the pilot area was determined to have the best channel sandstone development. A 2-layer geologic facies model was proposed. Oriented cores were included in the drilling of 24 wells in Phase II. North and northeast flow directions were indicated for the channel sandstones. During Phase III four observation wells were cored. These wells were drilled at internals of 90ft (27 m) diagonally from earlier wells in the north and south block. Micellar injection for the pilot was completed in early 1979 and polmer injection followed.

  13. Factors controlling reservoir quality in tertiary sandstones and their significance to geopressured geothermal production. Annual report, May 1, 1979-May 31, 1980

    SciTech Connect

    Loucks, R.G.; Richmann, D.L.; Milliken, K.L.

    1980-07-01

    Differing extents of diagenetic modification is the factor primarily responsible for contrasting regional reservoir quality of Tertiary sandstones from the Upper and Lower Texas Gulf Coast. Detailed comparison of Frio sandstones from the Chocolate Bayou/Danbury Dome area, Brazoria County, and Vicksburg sandstones from the McAllen Ranch Field area, Hidalgo County, reveals that extent of diagenetic modification is most strongly influenced by (1) detrital mineralogy and (2) regional geothermal gradients. Vicksburg sandstones from the McAllen Ranch Field area are less stable, chemically and mechanically, than Frio sandstones from the Chocolate Bayou/Danbury dome area. Vicksburg sandstones are mineralogically immature and contain greater proportions of feldspars and rock fragments than do Frio sandstones. Thr reactive detrital assemblage of Vicksubrg sandstones is highly susceptible to diagenetic modification. Susceptibility is enhanced by higher than normal geothermal gradients in the McAllen Ranch Field area. Thus, consolidation of Vicksburg sandstones began at shallower depth of burial and precipitation of authigenic phases (especially calcite) was more pervasive than in Frio sandstones. Moreover, the late-stage episode of ferroan calcite precipitation that occluded most secondary porosity in Vicksburg sandstones did not occur significantly in Frio sandstones. Therefore, regional reservoir quality of Frio sandstones from Brazoria County is far better than that characterizing Vicksburg sandstones from Hidalgo County, especially at depths suitable for geopressured geothermal energy production.

  14. Ferron sandstone - stratigraphy and reservoir analogs, East-Central Utah

    SciTech Connect

    Anderson, P.B.; Ryer, T.A.; Chidsey, T.C. Jr.

    1996-06-01

    The Ferron Sandstone (Upper Cretaceous) crops out along the west flank of the San Rafael Swell of east-central Utah. Exposures were described on photomosaics to better define the stratigraphy, to enhance facies prediction, and establish rules for reservoir modeling within fluvial-deltaic rocks. Major regressive cycles are recognized as parasequence sets composed of several to many parasequences. Each of the seaward-stepping parasequence sets recognized in the Ferron begins with a rapidly thickening and stratigraphically climbing, wave-modified shoreface. In later stages of progradation, deposition is dominated by river influences. Continued regression of the seaway is recorded in outcrop and shows a complex history of delta lobe progradation, switching, and abandonment. Onlapping and stacking of parasequences creates a collage of potential reservoir sweet spots, baffles, and barriers within a parasequence set. Shoreface and delta-front deposits of the older parasequences are commonly eroded by younger distributary and meanderbelt systems that fed younger parasequences of the parasequence sets. The result is numerous and locally thick channel sandstone bodies incised into shoreface and delta-front deposits. Published studies and recently completed work show that upper shoreface, stream mouth-bar, and channel sandstones constitute the best potential reservoir rocks within the Ferron Sandstone.

  15. CHARACTERIZATION OF SANDSTONE RESERVOIRS FOR ENHANCED OIL RECOVERY: THE PERMIAN UPPER MINNELUSA FORMATION, POWDER RIVER BASIN, WYOMING.

    USGS Publications Warehouse

    Schenk, C.J.; Schmoker, J.W.; Scheffler, J.M.

    1986-01-01

    Upper Minnelusa sandstones form a complex group of reservoirs because of variations in regional setting, sedimentology, and diagenetic alteration. Structural lineaments separate the reservoirs into northern and southern zones. Production in the north is from a single pay sand, and in the south from multi-pay sands due to differential erosion on top of the Upper Minnelusa. The intercalation of eolian dune, interdune, and sabkha sandstones with marine sandstones, carbonates, and anhydrites results in significant reservoir heterogeneity. Diagenetic alterations further enhance heterogeneity, because the degree of cementation and dissolution is partly facies-related.

  16. Classification of six ordinary chondrites from Texas

    NASA Astrophysics Data System (ADS)

    Ehlmann, Arthur J.; Keil, Klaus

    1988-12-01

    Based on optical microscopy, modal and electron microprobe analyses, six ordinary chondrites from Texas were classified in compositional groups, petrologic types, and shock facies. These meteorites are Comanche (stone), L5c; Haskell, L5c; Deport (a), H4b; Naruna (a), H4b; Naruna (b), H4b; and Clarendon (b), H5d.

  17. Metamorphic facies map of Alaska

    SciTech Connect

    Dusel-Bacon, C.; O-Rourke, E.F.; Reading, K.E.; Fitch, M.R.; Klute, M.A.

    1985-04-01

    A metamorphic-facies of Alaska has been compiled, following the facies-determination scheme of the Working Group for the Cartography of the Metamorphic Belts of the World. Regionally metamorphosed rocks are divided into facies series where P/T gradients are known and into facies groups where only T is known. Metamorphic rock units also are defined by known or bracketed age(s) of metamorphism. Five regional maps have been prepared at a scale of 1:1,000,000; these maps will provide the basis for a final colored version of the map at a scale of 1:2,500,000. The maps are being prepared by the US Geological Survey in cooperation with the Alaska Division of Geological and Geophysical Surveys. Precambrian metamorphism has been documented on the Seward Peninsula, in the Baird Mountains and the northeastern Kuskokwim Mountains, and in southwestern Alaska. Pre-Ordovician metamorphism affected the rocks in central Alaska and on southern Prince of Wales Island. Mid-Paleozoic metamorphism probably affected the rocks in east-central Alaska. Most of the metamorphic belts in Alaska developed during Mesozoic or early Tertiary time in conjuction with accretion of many terranes. Examples are Jurassic metamorphism in east-central Alaska, Early Cretaceous metamorphism in the southern Brooks Range and along the rim of the Yukon-Kovyukuk basin, and late Cretaceous to early Tertiary metamorphism in the central Alaska Range. Regional thermal metamorphism was associated with multiple episodes of Cretaceous plutonism in southeastern Alaska and with early Tertiary plutonism in the Chugach Mountains. Where possible, metamorphism is related to tectonism. Meeting participants are encouraged to comment on the present version of the metamorphic facies map.

  18. Reverse weathering, the carbonate-feldspar system, and porosity evolution during burial of sandstones

    SciTech Connect

    Milliken, K.L.; Land, L.S. )

    1991-03-01

    Acid generated by reverse weathering in mudrocks drives linked reactions involving carbonates and feldspars that in turn have a profound impact on the evolution of porosity during burial diagenesis of sandstones. In the Oligocene Frio Formation along the Texas Gulf Coast, petrographic evidence at various scales in both sandstones and shales, and modern pore fluid compositions are all consistent with this idea. Acid released during illitization of smectite dissolves marine skeletal and detrital carbonate in shales. Shales export excess H+, dissolved CA++, and CO{sub 2} to the sandstones. Resultant interaction of sandstones with these shale-derived fluids is primarily controlled by the feldspar content of the sandstones. If the sandstones contain reactive feldspar content of the sandstones. If the sandstones contain reactive feldspar, acid from the shales is effectively buffered, thus allowing precipitation of calcite as cements and grain replacements in the sandstones and maintenance of fluids with low pCO{sub 2}. Once the supply of reactive detrital feldspar is exhausted through dissolution and albitization, shale-derived H+ remobilizes carbonate in sandstones, generating secondary porosity and fluids with high pCO{sub 2}. Acid generated through thermal maturation of organic matter plays only a trivial role in this system of reactions because the quantity of acid required for dissolution of carbonate and feldspar far exceeds the amount of kerogen in the system. The balance between the local acid generation capacity of shales, the local buffering capacity of feldspars in sandstones, and the availability of externally derived acids and ions is the primary control on the sequence of reactions occurring during burial metamorphism of sandstones.

  19. Late Devonian glacigenic and associated facies from the central Appalachian Basin, eastern United States

    USGS Publications Warehouse

    Brezinski, D.K.; Cecil, C.B.; Skema, V.W.

    2010-01-01

    Late Devonian strata in the eastern United States are generally considered as having been deposited under warm tropical conditions. However, a stratigraphically restricted Late Devonian succession of diamictite- mudstonesandstone within the Spechty Kopf and Rockwell Formations that extends for more than 400 km along depositional strike within the central Appalachian Basin may indicate other wise. This lithologic association unconformably overlies the Catskill Formation, where a 3- to 5-m-thick interval of deformed strata occurs immediately below the diamictite strata. The diamictite facies consists of several subfacies that are interpreted to be subglacial, englacial, supraglacial meltout, and resedimented deposits. The mudstone facies that overlies the diamictite consists of subfacies of chaotically bedded, clast-poor mudstone, and laminated mudstone sub facies that represent subaqueous proximal debris flows and distal glaciolacustrine rhythmites or varvites, respectively. The pebbly sandstone facies is interpreted as proglacial braided outwash deposits that both preceded glacial advance and followed glacial retreat. Both the tectonic and depositional frameworks suggest that the facies were deposited in a terrestrial setting within the Appalachian foreland basin during a single glacial advance and retreat. Regionally, areas that were not covered by ice were subject to increased rainfall as indicated by wet-climate paleosols. River systems eroded deeper channels in response to sea-level drop during glacial advance. Marine facies to the west contain iceborne dropstone boulders preserved within contemporaneous units of the Cleveland Shale Member of the Ohio Shale.The stratigraphic interval correlative with sea-level drop, climate change, and glacigenic succession represents one of the Appalachian Basin's most prolific oil-and gas-producing intervals and is contemporaneous with a global episode of sea-level drop responsible for the deposition of the Hangenberg Shale/Sandstone

  20. Geometry and reservoir heterogeneity of tertiary sandstones: a guide to reservoir continuity and geothermal resource development

    SciTech Connect

    Morton, R.A.; Ewing, T.E.

    1981-01-01

    External and internal continuity of Tertiary sandstones are controlled by various factors including structural trends, sand body geometry, and the distribution of mineral framework, matrix, and intersticies within the sand body. Except for the limits imposed by faults, these factors are largely inherited from the depositional environment and modified during sandstone compaction and cementation. Sandstone continuity affects energy exploration and production strategies. The strategies range in scope from regional to site-specific and closely parallel a sandstone hierarchy. The hierarchy includes subdivisions ranking from genetically related aquifer systems down to individual reservoirs within a fault-bounded sandstone. Volumes of individual reservoirs are 50% less to 200% more than estimated from conventional geologic mapping. In general, mapped volumes under-estimate actual volumes where faults are nonsealing and overestimate actual volumes where laterally continuous shale breaks cause reductions in porosity and permeability. Gross variations in these pore properties can be predicted on the basis of internal stratification and sandstone facies. Preliminary analyses indicate that large aquifers are found where barrier and strandplain sandstones parallel regional faults or where fluvial (meandering) channels trend normal to regional faults. Within these sand bodies, porosity and permeability are highest in large-scale crossbedded intervals and lowest in contorted, bioturbated, and small-scale ripple cross-laminated intervals.

  1. Geochemistry and hydrodynamics of deep formation brines in the Palo Duro and Dalhart basins, Texas, U.S.A.

    NASA Astrophysics Data System (ADS)

    Bassett, R. L.; Bentley, M. E.

    1982-11-01

    Geological characterization of evaporite deposits as potential host rocks for radioactive waste burial must include hydrogeological investigations on both local and regional scales. The Palo Duro and Dalhart basins of Texas contain candidate salt deposits which are underlain by shelf carbonates and fan-delta sandstones. These basins are ancient intracratonic elements exhibiting regional eastward flow in the deep brine aquifers. Pressures in these aquifers are "subnormal"; however, the major component of flow appears to be parallel to bedding owing to the low permeability of the overlying evaporite strata in the central part of the basin. Salinities computed from geophysical logs or obtained from chemical analyses indicate only small aberrations in the regional salinity profile for brines in carbonate rocks and sandstones of Late Pennsylvanian—Early permian age. Brines reflect reactivity with the host rock deriving salinity primarily from evaporite facies and at present, apparently follow the anhydrite and calcite phase boundaries. Substantial outgassing of CO 2 and oxidation of ferrous iron appear to have occurred during collection of the samples during wildcat drilling by industry. Mass-transfer computer programs have been used to determine the most probable in situ brine composition. Additional support for the computed equilibrium state is the correlation between computed PCO 2 in the brines and observed PCO 2 in adjacent natural gas reservoirs.

  2. Cyclic sedimentation, depositional environments, and facies distribution of the Permian Paddock member of the Yeso Formation, Vacuum (Glorieta) field, northwest shelf of the Permian basin

    SciTech Connect

    Burnham, D.E. ); Womochel, D.R. )

    1992-04-01

    The Vacuum (Glorieta) field is located on the northwest shelf of the Permian basin in central Lea County, New Mexico. Cumulative oil production of 62 MMBO is primarily from the upper 100 ft of the Leonardian Paddock Member of the Yeso Formation. Cores from 10 wells were examined to identify lithologies and facies relationships. Five lithofacies were identified: (1) fine-grained quartz sandstone/siltstone facies, (2) pelletoid mudstone facies, (3) skeletal packstone/wackestone facies, (4) oolitic-pelletoid grainstone facies, and (5) crystalline dolomite facies. These lithofacies occur sequentially in four shoaling-upward cycles that can be correlated throughout much of the study area. Three major depositional environments are recognized in the Paddock Member of the Yeso Formation: (1) a subtidal open-marine environment in which the oolitic grainstone facies was deposited, (2) a subtidal protected shallow-marine environment where the skeletal packstone/wackestone facies was deposited, and (3) a subtidal to supratidal restricted shallow-marine environment where the pelletoid mudstone facies accumulated. Facies analysis indicates that the Paddock Member was deposited on a broad shallow-marine shelf. Numerous shoaling-upward cycles are possibly related to worldwide Permian sea level fluctuations. Porosity development is enhanced at the upper surface of each shoaling-upward cycle by dissolution of fossil fragments and grains.

  3. Elevated Uranium in Aquifers of the Jacobsville Sandstone

    NASA Astrophysics Data System (ADS)

    Sherman, H.; Gierke, J.

    2003-12-01

    The EPA has announced a new standard for uranium in drinking water of 30 parts per billion (ppb). This maximum contaminant level (MCL) takes effect for community water supplies December 2003. The EPA's ruling has heightened awareness among residential well owners that uranium in drinking water may increase the risk of kidney disease and cancer and has created a need for a quantified, scientific understanding of the occurrence and distribution of uranium isotopes in aquifers. The authors are investigating the occurrence of elevated uranium in northern Michigan aquifers of the Middle Proterozoic Jacobsville sandstone, a red to mottled sequence of sandstones, conglomerates, siltstones and shales deposited as basin fill in the 1.1 Ga Midcontinent rift. Approximately 25% of 300 well water samples tested for isotopic uranium have concentrations above the MCL. Elevated uranium occurrences are distributed throughout the Jacobsville sandstone aquifers stretching across Michigan's Upper Peninsula. However, there is significant variation in well water uranium concentrations (from 0.01 to 190 ppb) and neighboring wells do not necessarily have similar concentrations. The authors are investigating hydrogeologic controls on ground water uranium concentrations in the Jacobsville sandstone, e.g. variations in lithology, mineralogy, groundwater residence time and geochemistry. Approximately 2000' of Jacobsville core from the Amoco St. Amour well was examined in conjunction with the spectral gamma ray log run in the borehole. Spikes in equivalent uranium (eU) concentration from the log are frequently associated with clay and heavy mineral layers in the sandstone core. The lithology and mineralogy of these layers will be determined by analysis of thin sections and x-ray diffraction. A portable spectrometer, model GRS-2000/BL, will be used on the sandstone cliffs along Lake Superior to characterize depositional and lithologic facies of the Jacobsville sandstone in terms of

  4. Influence of relative sea level on facies, stacking patterns and reservoir heterogeneity: Middle Jurassic Brent group, UK North Sea

    SciTech Connect

    Jennette, D.C. )

    1996-01-01

    The lower Brent Group, above the genetically distinct lowstand deposits of the Broom Formation, is a progradational sequence set made up of the lower- shoreface Rannoch, the upper-shoreface and beach-plain Etive, and the back-barrier Lower Ness Formations. Much of the reservoir heterogeneity in this sandstone-rich succession can be attributed to facies and stacking-pattern variations within higher frequency systems tracts. Highstand systems tracts have strongly offlapping progradational geometries. Sweep efficiency is influenced by: (1) seaward-dipping, mica-rich bed-sets; (2) high-quality ebb tidal-delta sandstone bodies; and (3) the sharp increase in reservoir quality at the sub-horizontal base of the upper shoreface. The increased permeability leads water in the Etive to overrun oil in the Rannoch. Horizontal wells are targeting unswept reserves in the lower-permeability facies. Relative falls in sea level punctuated highstand progradation and led to the subaerial erosion of the Etive and Rannoch formations. Lowstand deposits are contained within incised valleys and consist of fluvial sandstones, coastal-plain mudstones and coal. Well-performance anomalies and abrupt variations in sandstone thickness are associated with the heterogeneous valley-fills. Shoreface sedimentation resumed during transgressive systems tracts. High sediment flux enabled the nearshore system to stack aggradationally. Diachronous lithostratigraphy, aggradation of the heterolithic back-barrier Ness Formation, interbedding of Rannoch facies in the lower Etive and increased carbonate cement in the lower shoreface Rannoch mark this systems tract.

  5. Silurian and Devonian in Vietnam—Stratigraphy and facies

    NASA Astrophysics Data System (ADS)

    Thanh, Tống Duy; Phương, Tạ Hoàng; Janvier, Philippe; Hùng, Nguyễn Hữu; Cúc, Nguyễn Thị Thu; Dương, Nguyễn Thùy

    2013-09-01

    Silurian and Devonian deposits in Viet Nam are present in several zones and regions, including Quang Ninh, East Bac Bo, and West Bac Bo Zones of the Bac Bo Region, the Dien Bien-Nghe An and Binh Tri Thien Zones of the Viet-Lao Region, and the South Trung Bo, and Western Nam Bo Zones of the South Viet Nam Region (Fig. 1). The main lithological features and faunal composition of the Silurian and Devonian Units in all these zones are briefly described. The Silurian consists of deep-water deposits of the upper parts of the Co To and Tan Mai Formations in the Quang Ninh Zone, the upper parts of the Phu Ngu Formation in the East Bac Bo Zone and the upper parts of the Long Dai and Song Ca Formations in the Viet-Lao Region. Shallow water facies Silurian units containing benthic faunas are more widely distributed, including the upper part of the Sinh Vinh and Bo Hieng Formations in the West Bac Bo Zone, the Kien An Formation in the Quang Ninh Zone, and, in the Viet-Lao Region, the Dai Giang Formation and the upper part of the Tay Trang Formation. No Lower and Middle Devonian deposits indicate deep water facies, but they are characterized by different shallow water facies. Continental to near shore, deltaic facies characterize the Lower Devonian Song Cau Group in the East Bac Bo Zone, the Van Canh Formation in the Quang Ninh Zone, and the A Choc Formation in the Binh Tri Thien Zone. Similar facies also occur in the Givetian Do Son Formation of the Quang Ninh Zone, and the Tan Lap Formation in the East Bac Bo Zone, and consist of coarse terrigenous deposits—cross-bedded conglomerates, sandstone, etc. Most Devonian units are characterized by shallow marine shelf facies. Carbonate and terrigenous-carbonate facies dominate, and terrigenous facies occur in the Lower and Middle Devonian sections in some areas only. The deep-water-like facies is characteriztic for some Upper Devonian formations in the Bac Bo (Bang Ca and Toc Tat Formations) and Viet-Lao Regions (Thien Nhan and

  6. Trilobites from Lower Mississippian starved basin facies of the southern United States

    USGS Publications Warehouse

    Brezinski, D.K.

    1998-01-01

    A distinctive trilobite fauna occurs within condensed statigraphic sections of the Lower Mississippian (Tournaisian) Chappel Limestone of the Llano region of Texas, the Welden Limestone of Oklahoma, and the Chouteau Limestone of Union County, Illinois. The seven species comprising this fauna are interpreted to have inhabited sediment-starved basinal environments. The starved-basin facies existed in the south-central United States throughout the Tournaisian (Kinderhookian to Osagean). Two species from this fauna, Australosutura llanoensis, and Carbonocoryphe planucauda, are new. The remaining five species, Griffithidella doris (Hall), Griffithidella alternata (Girty), Carbonocoryphe depressa (Girty), Thigiffides roundyi (Girty), and Pudoproetus chappelensis (Hessler), are restricted to starved-basin facies.

  7. Sandstones of unexpectedly high diffusibility.

    PubMed

    Bashar, Khairul; Tellam, John H

    2011-03-25

    Measurements have been made of diffusion coefficients (D(i)=-mass flux/concentration gradient) using a double reservoir, steady-state method with two tracers, CaBr(2) and amino-G-acid, on intact samples of Triassic red-bed sandstone from northwest England. Diffusibility (D'=D(i)/diffusion coefficient in water) averages 0.124, ranging between 0.075 and 0.215 (porosity 0.1 to 0.24), very similar for the two tracers. Implied tortuosities (actual path length/straight line length) average 1.21 (range 1.06 to 1.47), with constrictivities close to 1. In comparison with limited red-bed sandstone data from elsewhere, these D' values are up to 4 times greater, and tortuosity correspondingly lower. Re-interpretation of formation factor data from previous studies on shallow sandstone samples also from northwest England confirms that diffusibility is significantly higher in these sandstones than others from similar palaeoenvironment/stratigraphic units. The lower tortuosities appear to result from the relatively high permeability, open fabric of the rock, properties likely to be present in shallow sandstone systems used for water supply. It is concluded that diffusion rates may, in some shallow freshwater-containing continental sandstone systems, be significantly greater than is implied by estimates of sandstone diffusibility current in the literature. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Geology of the Southern Guadalupe Mountains, Texas

    USGS Publications Warehouse

    King, Philip B.

    1948-01-01

    This report deals with an area of 425 square miles in the western part of Texas, immediately south of the New Mexico line. The area comprises the south end of the Guadalupe Mountains and the adjacent part of the Delaware Mountains; it includes the highest peaks in the State of Texas. The area is a segment of a large mountain mass that extends 50 miles or more northward and southward. The report describes the geology of the area, that is, the nature of its rocks, tectonics, and surface features, and the evidence that they give as to the evolution of the area through geologic time. Incidental reference is made to the geology of surrounding regions in order to place the area in its environment. Stratigraphy of Permian rocks - The consolidated rocks of the area are all marine sediments of Permian age, whose total exposed thickness is about 4,000 feet. Most of the rocks contain abundant invertebrate fossils, some of which were described by B. F. Shumard in 1858. They were made famous by the classic study of G. H. Girty in 1908. The rocks consist chiefly of sandstones and limestones of various textures and structures, and are notable for their abrupt change from one rock type into another within short distances. This characteristic is believed to have been caused by the rocks being laid down on the margin of the Delaware Basin, a structural feature of Permian time. The margin lay between the more rapidly subsiding basin and a less rapidly subsiding shelf area to the northwest. The lowest exposed formation is the Bone Spring limestone. Two deep wells indicate that it is underlain by the Hueco limestone (of Carboniferous or Permian age), and this by rocks of Pennsylvanian age. The Bone Spring is predominantly black, thin-bedded limestone to the southeast, in the basin area, but to the northwest this facies changes into gray, thicker-bedded limestone. At the margin of the basin, the formation is raised along the Bone Spring flexure, which was apparently in movement toward

  9. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio Fluvial-Deltaic reservoirs of south Texas. Technical progress report, April 1, 1996--June 30, 1996

    SciTech Connect

    Tyler, N.; Levey, R.A.

    1996-07-11

    Advanced reservoir characterization techniques have been applied to selected reservoirs in the Frio Fluvial-Deltaic Sandstone (Vicksburg Fault Zone) trend of South Texas in order to maximize the economic producibility of resources in this mature oil play. More than half of the reservoirs in this depositionally complex play have already been abandoned, and large volumes of oil may remain unproduced unless advanced characterization techniques are applied to define untapped, incompletely drained, and new pool reservoirs as suitable targets for near-term recovery methods. This project has developed interwell-scale geological facies models and has assessed engineering attributes of Frio fluvial-deltaic reservoirs in selected fields in order to characterize reservoir architecture, flow unit boundaries, and the controls that these characteristics exert on the location and volume of unrecovered mobile and residual oil. Results of these studies led to the identification of specific opportunities to exploit these heterogeneous reservoirs for incremental recovery by recompletion and strategic infill drilling.

  10. Structural and stratigraphic compartmentalization of the Terry Sandstone and effects on reservoir fluid distributions: Latham Bar Trend, Denver Basin: Colorado

    SciTech Connect

    Al-Raisi, M.H.; Slatt, R.M.; Decker, M.K.

    1996-01-01

    The Latham Bar Trend, located in the Denver Basin of Colorado, is an elongate sandstone which extends in a northwest direction for more than 6 mi and is up to 1-2 mi wide. It is now under infill drilling on 40-acre spacing, with more than 65 wells producing from the Upper Cretaceous Terry Sandstone. Detailed analysis of four cores and 210 wells suggests that the Terry Sandstone within the Lantham Bar Trend was deposited in an open marine environment. Reservoir quality, particularly permeability, is primarily facies controlled, and secondarily controlled by diagenetic products. Estimated ultimate recovery (EUR) values in wells are related to thickness of this facies. Structural analysis indicates the Trend is dissected by a series of northeast-trending, northwest-dipping faults with vertical displacements of 30-100 ft. (9-30 m). The faults are interpreted to be sealing, separating the Terry Sandstone into isolated fault blocks, on the basis of the following criteria: (1) normalized GOR values exhibit a non-systematic areal distribution across the trend, but show systematic up-structure increases in GOR within individual fault blocks; (2) initial API gravity values from different wells also are non-systematically distributed areally across the Trend, but show similar groupings within fault blocks; (3) EUR values within each fault block exhibit a positive correlation with thickness of cross-bedded sandstone facies; (4) individual wells with specific normalized GOR values occur at lower structural elevations than wells in adjacent fault blocks with lower GORs, giving rise to structural reversal of fluid distributions. Recognition of the facies control on reservoir quality, reservoir facies thickness, sealing capacity of normal faults, and resultant compartmentalization can help explain complex stratigraphic and areas distribution patterns of gas and oil in these and other strata in the Denver Basin and to maximize reservoir producibility and exploration success.

  11. Fluvial facies architecture in small-scale river systems in the Upper Dupi Tila Formation, northeast Bengal Basin, Bangladesh

    NASA Astrophysics Data System (ADS)

    Royhan Gani, M.; Mustafa Alam, M.

    2004-11-01

    The late stage basin-fill history of the fluvial Dupi Tila Group (Plio-Pleistocene) is described. These rocks have been deposited in the Sylhet trough, a sub-basin of the Bengal Basin, in a foreland basin setting. This outcrop study, carried out in Sylhet, Bangladesh, presents the first detailed facies analysis of the Upper Dupi Tila Formation. Four facies have been identified: trough cross-bedded sandstone (St), ripple cross-laminated sandstone (Sr), finely laminated mud with ripples (Fl), and massive mud with rootlets (Fm). Facies analysis supplemented with embedded Markov chain analysis, reveals small-scale fining-upward cycles (average 4.5 m thick). Facies architectural elements include channel (CH), lateral accretion (LA), sandy bedforms (SB), and overbank fines (OF) with limited vertical and lateral connectivity of the sand bodies. The average channel depth and width is 5 and 30 m, respectively. Sand body geometry ranges from tabular, to sheet, to shoestring with a 0.45 net to gross ratio. This study shows that the Upper Dupi Tila Formation is composed of small-scale, mudstone-reach meandering river deposits. In Bangladesh, the Dupi Tila Formation is the main aquifer presently being utilized. Understanding of facies architecture and sand body geometry of this Formation is crucial in examining the issue of arsenic and other contaminations of ground water in Bangladesh.

  12. Internal geometry, seismic facies, and petroleum potential of canyons and inner fan channels of the Indus submarine fan

    SciTech Connect

    McHargue, T.R.; Webb, J.E.

    1986-02-01

    The Indus Fan, the second largest submarine fan in the world, covers 1,250,000 km/sup 2/ (500,000 mi/sup 2/) and contains sediment more than 7 km (23,000 ft) thick. Multichannel (24-fold) CDP seismic data provide the bases for evaluating the Indus Fan and consist of four seismic facies. Of these, only the high-amplitude, discontinuous (H-D) facies is thought to contain reservoir-quality sandstones. The H-D facies is confined to the axes of leveed channels. Canyon-channel systems that fed the fan in the past can be divided into three zones. The degradational zone is composed of an erosional canyon complex filled by prodelta mud. The transitional zone, located near the canyon mouth, consists of superimposed channels that initially were erosional but eventually aggraded and developed levees. The headward termination of the H-D facies occurs in this zone. The aggradational zone consists of superimposed leveed channels confined solely by their own levees. The proximal termination of the H-D facies near canyon mouths implies the presence of reservoir-quality sandstone surrounded by source/seal mudstone in the transitional zone. This stratigraphic trapping geometry and structural leads may represent a vast, untapped petroleum province.

  13. Sandstone weathering processes damaging prehistoric rock paintings at the Albarracin Cultural Park, NE Spain

    NASA Astrophysics Data System (ADS)

    Benito, G.; Machado, M. J.; Sancho, C.

    1993-09-01

    The rock paintings in cliff-foot caves of the Albarracin Cultural Park are known as some of the most important evidences of the Levantine prehistoric art of Spain (8000 3000 BP). The paintings are on sandstone (Buntsandstein facies) of Triasic age, which may develop intense weathering. The analysis of the variables controlling the weathering indicate that salt and wetting-drying weathering are responsible for granular disintegration and flaking, which lead to rock painting deterioration.

  14. Upper Jurassic and Lower Cretaceous facies relationships in a passive margin basin, western North Atlantic

    SciTech Connect

    Prather, B.E.

    1988-02-01

    Correlation of facies from hydrocarbon-bearing continental and transitional marine sandstones to time-equivalent high-energy shelf-margin carbonates provide insight into hydrocarbon habitats of the Baltimore Canyon basin. These facies occur within a thick (> 10,000 ft) prograded wedge of shelf sediments in this passive margin basin. Wells drilled to test structural closures in shallow-water (< 600 ft) areas of Baltimore Canyon penetrate clastic facies which are time-equivalent to the downdip carbonate facies tested in deep-water wells. Numerous hydrocarbon shows, including a noncommercial gas and gas-condensate accumulation, occur with sandstone units that were deposited in prograding continental/fluvial and transitional marine environments located updip of the Oxfordian/Kimmeridgian carbonate shelf edge. The continental and transitional facies are overlain by a fine-grained deltaic complex which forms a regionally extensive top seal unit. The deltaic complex was deposited during aggradation of the Kimmeridgian through Berriasian shelf-margin carbonates penetrated by the deep-water wells. Deep-water wells (> 5000 ft) drilled off the continental shelf edge to test large structural closures along the downdip termination of the Upper Jurassic/Lower Cretaceous carbonate shelf edge encountered no significant hydrocarbon shows. Reservoir rocks in these wells consist of (1) oolite grainstone which was deposited within a shoal-water complex located at the Aptian shelf edge, and (2) coral-stromatoporoid grainstone and boundstone which formed an aggraded shelf-margin complex located at the Kimmeridgian through Berriasian shelf edge. Structural closures with reservoir and top seals are present in both updip and downdip trends. The absence of hydrocarbon shows in downdip carbonate reservoirs suggests a lack of source rocks available to charge objectives at the shelf margin.

  15. Multiscale Fractal Characterization of Hierarchical Heterogeneity in Sandstone Reservoirs

    NASA Astrophysics Data System (ADS)

    Liu, Yanfeng; Liu, Yuetian; Sun, Lu; Liu, Jian

    2016-07-01

    Heterogeneities affecting reservoirs often develop at different scales. Previous studies have described these heterogeneities using different parameters depending on their size, and there is no one comprehensive method of reservoir evaluation that considers every scale. This paper introduces a multiscale fractal approach to quantify consistently the hierarchical heterogeneities of sandstone reservoirs. Materials taken from typical depositional pattern and aerial photography are used to represent three main types of sandstone reservoir: turbidite, braided, and meandering river system. Subsequent multiscale fractal dimension analysis using the Bouligand-Minkowski method characterizes well the hierarchical heterogeneity of the sandstone reservoirs. The multiscale fractal dimension provides a curve function that describes the heterogeneity at different scales. The heterogeneity of a reservoir’s internal structure decreases as the observational scale increases. The shape of a deposit’s facies is vital for quantitative determination of the sedimentation type, and thus enhanced oil recovery. Characterization of hierarchical heterogeneity by multiscale fractal dimension can assist reservoir evaluation, geological modeling, and even the design of well patterns.

  16. Eolian sandstone unit of Morrison Formation, central Wyoming

    SciTech Connect

    Uhlir, D.M.

    1986-08-01

    The fine-grained quartzarenite that overlies the Sundance Formation in the southwestern Powder River basin, Wind River basin, and southern Bighorn basin is interpreted as being primarily the result of eolian deposition. This unit, often more than 20 m (65.6 ft) thick, is the probable correlative of the Unkpapa Sandstone member of the Morrison Formation of the southeastern Black Hills region. An eolian interpretation is based on the presence of large-scale sets of high-angle, planar cross-stratification. Observed considerable variation in the thickness of the unit is likely to be an expression of the depositional (dune-form) topography rather than the result of later erosion. Discrete dunes are exposed near Thermopolis along the northern margin of the unit: the transitional marine deposits of the uppermost Sundance formation are the most likely source of the wind-transported sand. Stratigraphic and facies relationships and lithologic similarity support correlation of the eolian unit with the Unkpapa Sandstone. Together, the units represent regions of significant eolian deposition within the predominantly fluvial Morrison depositional environment. The properties of the eolian sandstone, its thickness, its superposition above the marine Sundance Formation, and the possibility of its persistence in the subsurface of the southern Powder River basin give it potential as a petroleum reservoir. These anomalous eolian deposits may record the positions of gentle structures developed in central Wyoming and western South Dakota at the onset of, and in association with, Sevier compression.

  17. Sedimentology and reservoir potential of Matilija sandstone: an Eocene sand-rich deep-sea fan and shallow-marine complex, California

    SciTech Connect

    Link, M.H.; Welton, J.E.

    1982-10-01

    A deep-sea fan facies model for the Matilija Sandstone (southern California) regression from turbidite to shallow-marine to brackish deposits are documented. In addition, reservoir characteristics and the diagenetic history of the deep-sea fan complex is discussed. Despite thick, favorable source beds and generally good initial reservoir characteristics, the Matilija Sandstone is not a productive unit of the Ventura basin because of low reservoir permeability and porosity.

  18. Influence of depositional environment and diagenesis on gas reservoir properties in St. Peter Sandstone, Michigan basin

    SciTech Connect

    Harrison, W.B. III; Turmelle, T.M.; Barnes, D.A.

    1987-05-01

    The St. Peter Sandstone in the Michigan basin subsurface is rapidly becoming a major exploration target for natural gas. This reservoir was first proven with the successful completion of the Dart-Edwards 7-36 (Falmouth field, Missaukee County, Michigan) in 1981. Fifteen fields now are known, with a maximum of three producing wells in any one field. The production from these wells ranges from 1 to more than 10 MMCFGD on choke, with light-gravity condensate production of up to 450 b/d. Depth to the producing intervals ranges from about 7000 ft to more than 11,000 ft. The St. Peter Sandstone is an amalgamated stack of shoreface and shelf sequences more than 1100 ft in thickness in the basin center and thinning to zero at the basin margins. Sandstone composition varies from quartzarenite in the coarser sizes to subarkose and arkose in the finer sizes. Thin salty/shaly lithologies and dolomite-cemented sandstone intervals separate the porous sandstone packages. Two major lithofacies are recognized in the basin: a coarse-grained, well-sorted quartzarenite with various current laminations and a fine-grained, more poorly sorted subarkose and arkose with abundant bioturbation and distinct vertical and horizontal burrows. Reservoir quality is influenced by original depositional and diagenetic fabrics, but there is inversion of permeability and porosity with respect to primary textures in the major lithofacies. The initially highly porous and permeable, well-sorted, coarser facies is now tightly cemented with syntaxial quartz cement, resulting in a low-permeability, poor quality reservoir. The more poorly sorted, finer facies with initially lower permeabilities did not receive significant fluid flux until it passed below the zone of quartz cementation. This facies was cemented with carbonate which has subsequently dissolved to form a major secondary porosity reservoir.

  19. Reservoir characterization of Mesaverde (Campanian) bedload fluvial meanderbelt sandstones, northwestern Colorado

    SciTech Connect

    Jones, J.R. Jr.

    1984-04-01

    Reservoir characterization of Mesaverde meanderbelt sandstones is used to determined directional continuity of permeable zones. A 500-m (1600 ft) wide fluvial meanderbelt in the Mesaverde Group is exposed as laterally continuous 3-10-m (10-33-ft) high sandstone cliffs north of Rangely, Colorado. Forty-eight detailed measured sections through 3 point bar complexes oriented at right angles to the long axis of deposition and 1 complex oriented parallel to deposition were prepared. Sections were tied together by detailed sketches delineating and tracing major bounding surfaces such as scours and clay drapes. These complexes contain 3 to 8 multilateral sandstone packages separated by 5-20 cm (2-8 in.) interbedded siltstone and shale beds. Component facies are point bars, crevasse splays, chute bars, and floodplain/overbank deposits. Two types of lateral accretion surfaces are recognized in the point bar facies. Gently dipping lateral accretions containing fining-upward sandstone packages. Large scale trough cross-bedding at the base grades upward into ripples and plane beds. Steeply dipping lateral accretion surfaces enclose beds characterized by climbing ripple cross laminations. Bounding surfaces draped by shale lags can seal vertically stacked point bars from reservoir communication. Scoured boundaries allow communication in some stacked point bars. Crevasse splays showing climbing ripples form tongues of very fine-grained sandstone which flank point bars. Chute channels commonly cut upper point bar surfaces at their downstream end. Chute facies are upward-fining with small scale troughs and common dewatering structures. Siltstones and shales underlie the point bar complexes and completely encase the meanderbelt system. Bounding surfaces at the base of the complexes are erosional and contain large shale rip-up clasts.

  20. Petrophysics of Lower Silurian sandstones and integration with the tectonic-stratigraphic framework, Appalachian basin, United States

    USGS Publications Warehouse

    Castle, J.W.; Byrnes, A.P.

    2005-01-01

    Petrophysical properties were determined for six facies in Lower Silurian sandstones of the Appalachian basin: fluvial, estuarine, upper shoreface, lower shoreface, tidal channel, and tidal flat. Fluvial sandstones have the highest permeability for a given porosity and exhibit a wide range of porosity (2-18%) and permeability (0.002-450 md). With a transition-zone thickness of only 1-6 m (3-20 ft), fluvial sandstones with permeability greater than 5 md have irreducible water saturation (Siw) less than 20%, typical of many gas reservoirs. Upper shoreface sandstones exhibit good reservoir properties with high porosity (10-21%), high permeability (3-250 md), and low S iw (<20%). Lower shoreface sandstones, which are finer grained, have lower porosity (4-12%), lower permeability (0.0007-4 md), thicker transition zones (6-180 m [20-600 ft]), and higher S iw. In the tidal-channel, tidal-flat, and estuarine facies, low porosity (average < 6%), low permeability (average < 0.02 md), and small pore throats result in large transition zones (30-200 m; 100-650 ft) and high water saturations. The most favorable reservoir petrophysical properties and the best estimated production from the Lower Silurian sandstones are associated with fluvial and upper shoreface facies of incised-valley fills, which we interpret to have formed predominantly in areas of structural recesses that evolved from promontories along a collisional margin during the Taconic orogeny. Although the total thickness of the sandstone may not be as great in these areas, reservoir quality is better than in adjacent structural salients, which is attributed to higher energy depositional processes and shallower maximum burial depth in the recesses than in the salients. Copyright ??2005. The American Association of Petroleum Geologists. All rights reserved.

  1. Reservoir heterogeneity within Bartlesville sandstone, Glenn Pool oil field, Creek County, Oklahoma

    SciTech Connect

    Kuykendall, M.D. )

    1989-08-01

    The extent of reservoir heterogeneity within the Middle Pennsylvanian (Desmoinesian) Bartlesville Glenn sandstone in the 160-ac William Berryhill unit was established using more than 70 modern well log suites and 18 cores. Reservoir characterization of genetic sandstone units within the Bartlesville is based on differences in lithologic characteristics, sedimentologic features, porosity, permeability, and log-response characteristics. The upper delta-plain depositional setting of the Bartlesville was such that short-distance changes in facies created many small-scale heterogeneities. Recognition of laterally continuous distinct units in the Bartlesville sandstone requires integration of well log signatures and rock properties. Although thin intervals of interbedded sandstone and shale, and calcite-cemented sandstone are discontinuous laterally, they tend to compartmentalize portions of the reservoir. The Bartlesville sandstone is presently a sublitharenite-litharenite, even after its composition has been influenced strongly by diagenetic processes. Porosity is mostly secondary owing to the dissolution of unstable framework grains. Distribution and general trends of porosity are affected by changes in composition and pore geometry in particular rock units as well as local changes in depositional trend.

  2. Diagenetic contrast of sandstones in hydrocarbon prospective Mesozoic rift basins (Ethiopia, UK, USA)

    NASA Astrophysics Data System (ADS)

    Wolela, A.

    2014-11-01

    Diagenetic studied in hydrocarbon-prospective Mesozoic rift basins were carried out in the Blue Nile Basin (Ethiopia), Ulster Basin (United Kingdom) and Hartford Basin (United States of America). Alluvial fan, single and amalgamated multistorey meandering and braided river, deep and shallow perennial lake, shallow ephemeral lake, aeolian and playa mud-flat are the prominent depositional environments. The studied sandstones exhibit red bed diagenesis. Source area geology, depositional environments, pore-water chemistry and circulation, tectonic setting and burial history controlled the diagenetic evolution. The diagenetic minerals include: facies-related minerals (calcrete and dolocrete), grain-coating clay minerals and/or hematite, quartz and feldspar overgrowths, carbonate cements, hematite, kaolinite, illite-smectite, smectite, illite, chlorite, actinolite, laumontite, pyrite and apatite. Diversity of diagenetic minerals and sequence of diagenetic alteration can be directly related to depositional environment and burial history of the basins. Variation in infiltrated clays, carbonate cements and clay minerals observed in the studied sandstones. The alluvial fan and fluviatile sandstones are dominated by kaolinite, illite calcite and ferroan calcite, whereas the playa and lacustrine sandstones are dominated by illite-smectite, smectite-chlorite, smectite, chlorite, dolomite ferroan dolomite and ankerite. Albite, pyrite and apatite are predominantly precipitated in lacustrine sandstones. Basaltic eruption in the basins modified mechanically infiltrated clays to authigenic clays. In all the studied sandstones, secondary porosity predominates over primary porosity. The oil emplacement inhabited clay authigenesis and generation of secondary porosity, whereas authigenesis of quartz, pyrite and apatite continued after oil emplacement.

  3. Facies architecture of a silicic intrusion-dominated volcanic centre at Highway Reward, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Doyle, M. G.; McPhie, J.

    2000-06-01

    The Highway-Reward massive sulphide deposit is hosted by a silicic volcanic succession in the Cambro-Ordovician Seventy Mile Range Group, northeastern Australia. Three principal lithofacies associations have been identified in the host succession: the volcanogenic sedimentary facies association, the primary volcanic facies association and the resedimented syn-eruptive facies association. The volcanogenic sedimentary facies association comprises volcanic and non-volcanic siltstone and sandstone turbidites that indicate submarine settings below storm wave base. Lithofacies of the primary volcanic facies association include coherent rhyolite, rhyodacite and dacite, and associated non-stratified breccia facies (autoclastic breccia and peperite). The resedimented volcaniclastic facies association contains clasts that were initially formed and deposited by volcanic processes, but then redeposited by mass-flow processes. Resedimentation was more or less syn-eruptive so that the deposits are essentially monomictic and clast shapes are unmodified. This facies association includes monomictic rhyolitic to dacitic breccia (resedimented autoclastic facies), siltstone-matrix rhyolitic to dacitic breccia (resedimented intrusive hyaloclastite or resedimented peperite) and graded lithic-crystal-pumice breccia and sandstone (pumiceous and crystal-rich turbidites). The graded lithic-crystal-pumice breccia and sandstone facies is the submarine record of a volcanic centre(s) that is not preserved or is located outside the study area. Pumice, shards, and crystals are pyroclasts that reflect the importance of explosive magmatic and/or phreatomagmatic eruptions and suggest that the source vents were in shallow water or subaerial settings. The lithofacies associations at Highway-Reward collectively define a submarine, shallow-intrusion-dominated volcanic centre. Contact relationships and phenocryst populations indicate the presence of more than 13 distinct porphyritic units with a

  4. Facies mosaic in a fiord: Carboniferous-Permian Talchir Formation, India

    SciTech Connect

    Bose, P.K.; Mukhopadhyay, G.; Bhattacharya, H.N.

    1988-01-01

    Facies analysis of the basal 37m of the Carboniferous-Permian Talchir Formation is a glacier-fed bedrock trough in Dudhi nala, Bihar, India, provides insight into the pattern of sedimentation of course gravels in a fiord. Rapid transitions between 11 recognized facies, together with their complex organization, random variability in bed thickness, and differences in clast, shape, size, and composition indicate coalescence of fans developed from numerous point sources bordering the elongated trough. Converging slide masses and lodgment tillites on the slopes flanking the trough give way to sediment gravity flow deposits composed of an array of conglomerates (matrix and clast supported with normal, inverse of absence of grading), attendant turbidite sands, and prodelta mud. The rheology of the in-trough flows ranged from plastic laminar to fluidal turbulent in response to flow from slope to floor of the trough. Rapid calving of icebergs during the onset of deglaciation established a wave regime at the mouth of the trough and deposited cross-stratified sandstone replete with dripstones. The impact of large dripstones landing triggered turbidity currents. Continued rise in water level led to eventual preservation of the fan complex under onlapping wave-built shoal facies that grade into a sequence of upward-thinning hummocky cross-stratified sandstone beds virtually devoid of dripstones.

  5. Lithological and geochemical facies of Shublik Formation (Triassic), North Slope, Alaska

    SciTech Connect

    Parrish, J.T.

    1985-04-01

    The Shublik Formation is a heterogeneous unit consisting of several distinct facies, including: (1) fossiliferous sandstone or siltstone; (2) glauconitic sandstone or siltstone; (3) siltstone, calcareous mudstone, or limestone with phosphate nodules; and (4) black, calcareous mudstone or black limestone, usually fossilferous. This sequence of lithologies is interpreted as having been deposited along an onshore-offshore (north to south) gradient. Bioturbation of the sediments is variable but generally decreases offshore. Organic carbon increases offshore, and phosphate increases from the paleoshoreline and decreases again farthest offshore. The distribution of glauconite, phosphate, and organic-carbon-rich rock is consistent with the facies expected in a zone that has a well-developed oxygen minimum. Glauconite is consistent with dysoxic conditions, and well-laminated, organic-carbon-rich rock in the offshore facies is consistent with anoxic conditions. High biologic productivity coupled with normal oceanic circulation may have caused the basin's low-oxygen conditions, as indicated by the presence of phosphate nodules and the extreme abundance of bivalves that have been interpreted to be pelagic. Phosphate indicates a high rate of supply of organic matter to the sediment-water interface, where it was mobilized from the organic matter within the anoxic zone, and reprecipitated at the zone's edges. Pelagic bivalves (Monotis and Halobia) are present in such large numbers as to suggest unusually abundant food supply; in addition, their distribution is consistent with mass dills, which are common among fish in zones.

  6. Modern Pearl River Delta and Permian Huainan coalfield, China: A comparative sedimentary facies study

    USGS Publications Warehouse

    Suping, P.; Flores, R.M.

    1996-01-01

    Sedimentary facies types of the Pleistocene deposits of the Modern Pearl River Delta in Guangdong Province, China and Permian Member D deposits in Huainan coalfield in Anhui Province are exemplified by depositional facies of anastomosing fluvial systems. In both study areas, sand/sandstone and mud/mudstone-dominated facies types formed in diverging and converging, coeval fluvial channels laterally juxtaposed with floodplains containing ponds, lakes, and topogenous mires. The mires accumulated thin to thick peat/coal deposits that vary in vertical and lateral distribution between the two study areas. This difference is probably due to attendant sedimentary processes that affected the floodplain environments. The ancestral floodplains of the Modern Pearl River Delta were reworked by combined fluvial and tidal and estuarine processes. In contrast, the floodplains of the Permian Member D were mainly influenced by freshwater fluvial processes. In addition, the thick, laterally extensive coal zones of the Permian Member D may have formed in topogenous mires that developed on abandoned courses of anastomosing fluvial systems. This is typified by Seam 13-1, which is a blanket-like body that thickens to as much as 8 in but also splits into thinner beds. This seam overlies deposits of diverging and converging, coeval fluvial channels of the Sandstone D, and associated overbank-floodplain deposits. The limited areal extent of lenticular Pleistocene peat deposits of the Modern Pearl River Delta is due to their primary accumulation in topogenous mires in the central floodplains that were restricted by contemporaneous anastomosing channels.

  7. The fauna of the Batesville sandstone of northern Arkansas

    USGS Publications Warehouse

    Girty, George H.

    1915-01-01

    The beds in northern Arkansas that lie between the Boone limestone (commonly regarded as representing the Burlington and Keokuk epochs) and the Pennsylvanian have been divided into several formations, named, in ascending order, Moorefield shale, Batesville sandstone, Fayetteville shale, and Pitkin limestone. These formations presumably are equivalent to those that hold a corresponding position in the typical Mississippian section of Iowa, Missouri, and Illinois, but the faunas which they have furnished show noteworthy differences from the typical faunas. It has therefore seemed desirable to investigate these faunas, especially as the facies which they present is found also in the faunas of several of the Southern States, such as Oklahoma, Mississippi, and Alabama. With this object in view, I published in 1911 a report on the fossils of the Moorefield shale. The fauna next to be considered in a systematic pursuance of such a plan as I have mentioned is that of the Batesville sandstone, but the fauna of the Batesville sandstone, as is well known, has already been described in a treatise by Prof. Stuart Weller. At first I considered the possibility of pretermitting the Batesville fauna and of substituting Prof. Weller's report for my own in a series of little monographs that are under contemplation. It soon became evident, however, that this would not be satisfactory because, whether by reason of having collections from a number of new localities or by reason of having more extensive collections from old ones, I found that the material at my command considerably increased the number of types known from the Batesville sandstone, among them being a few which were undescribed. In fact, while Prof. Weller's paper discusses only 30 species (aside from a few Bryozoan types not even generically distinguished) the present paper discusses 128 species. On this account it seemed to me essential to redescribe the fauna.

  8. Characteristics of deltaic deposits in the Cretaceous Pierre shale. Trinidad sandstone, and Vermejo formation. Raton Basin, Colorado

    SciTech Connect

    Flores, R.M.; Tur, S.M.

    1982-04-01

    The depositional models previously described for the regressive sequence of Upper Cretaceous Pierre Shale, Trinidad Sandstone, and Vermejo Formation lithologies in the Raton Basin, Colorado, indicate to some degree the constructional--and destructional--deltaic characteristics of the sequence. However, the relationships of specific deltaic environments and deltaic abandonment phases to coal accumulation and distribution in the Vermejo Formation are not well understood. Detailed facies analyses of closely spaced measured surface sections in the Trinidad and adjacent areas of Colorado reflect deposition in the river-influenced delta. That this deltaic system was accompanied by abandonment of subdeltas is indicated by a destructional-deltaic facies of heavily bioturbated, carbonaceous sandstones, siltstones, and shales best recorded in the delta front deposits of the Trinidad Sandstone. This destructional-deltaic facies commonly separates overlapped distributary mouth-bar sandstones. Like their modern counterparts in the Mississippi delta system, the abandoned delta-front deposits are affected by wave reworking, as indicated by their mature and clean characteristics, although associated offshore barrier islands apparently were not formed. Perhaps the difference between these modern and ancient deltaic deposits is related to associated basinal processes attendant to a uniformly subsiding system in the highly muddy prodeltaic depositional environment in the Raton Basin. Although abandonment of subdeltas had a limited influence on the characteristics of the Vermejo coal deposits, coal accumulation nevertheless remained primarily controlled by persistent organic sedimentation in interdistributary backswamps.

  9. Lithofacies and petrography of Wajid sandstone (Cambrian-Ordovician) Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Moshrif, M. A.; El-Hiti, A.

    Six lithofacies are recognized in the Wajid sandstone. These litofacies are identified as: silty and argillaceous sandstone; fine-grained sandstones; coarse-grained sandstones; pebbley to very coarse-grained sandstones; conglomerates and massive sandstones. Mineralogic composition suggests that the Wajid sandstone is considered clean sands for it consists 95% of quartz grains 5% heavy minerals, mica, potash feldspar, clay matrix, ferruginous cement and traces of carbonate cement. Quartz grain extinction types and inclusions plus heavy mineral types and shapes suggest nearby igneous and metamorphic sources for these deposits, i.e. the adjacent Arabian Shield rocks, in addition to repeated recycling of these sediments as indicated by the appearance of a small number of rounded to very rounded grains of heavy minerals. Furthermore, perhaps most of the secondary silica present in the Wajid was developed from solution and from silica reprecipitated later during periods of aeolian reworking of these fluvial sediments. Moreover, the ferruginous material in Wajid was very likely derived either from siderite or came in solution from igneous and metamorphic provenance or generally came from both sources. The carbonate material in the sediments might either be derived from post-Wajid carbonate formations or formed from solution of carbonate shells trapped in these sediments. X-ray diffraction analysis shows that kaolinite is the only clay mineral present in the Wajid deposits. On the other hand, spectroscopic analysis reveals the presence of Si, Mg, Al and Ca elements as major constituents in the Wajid sandstone. Moreover, according to facies characteristics, the Wajid sediments were deposited under conditions of fluvial environments.

  10. Analysis of glacier facies using satellite techniques

    USGS Publications Warehouse

    Williams, R.S.; Hall, D.K.; Benson, C.S.

    1991-01-01

    Landsat-derived reflectance is lowest for exposed ice and increases markedly at the transient snow line. Above the slush zone is a gradual increase in near-infrared reflectance as a result of decreasing grain-size of the snow, which characterizes drier snow. Landsat data are useful in measuring the areal extent of the ice facies, the slush zone within the wet-snow facies, the snow facies (combined wet-snow, percolation and dry-snow facies), and the respective position of the transient snow line and the slush limit. In addition, fresh snowfall and/or airborne contaminants, such as soot and tephra, can limit the utility of Landsat data for delineation of the glacier facies in some cases. -from Authors

  11. Controls on dolomitization in the reef facies of the Capitan Formation

    SciTech Connect

    Melim, L.A.; Scholle, P.A. )

    1992-04-01

    The degree of dolomitization in the reef facies of the Capitan Formation (Permian, Delaware basin, west Texas-New Mexico) was controlled by the amount of early marine cementation, which, in turn, was controlled by local depositional factors. Work on the Capitan forereef facies indicates dolomitization by refluxing penecontemporaneous backreef brines. These brines passed through the reef facies causing variable dolomitization. In the Guadalupe Mountains, the Capitan reef facies is well known for the extensive marine cementation that occluded most primary porosity and inhibited dolomitization. The rigid reef, however, fractured as it prograded over the compacting forereef facies. These fractures acted as channels for descending brines as evidenced by the dolomite halos commonly found on them. If marine cementation controlled dolomite distribution, what controlled marine cementation The Capitan reef in the Guadalupe Mountains is characterized by moderate progradation (5-7 km) and extensive marine cementation. Elsewhere, however, the Capitan prograded 2-3 times farther and generally lacks marine cementation. Apparently, rapid progradation results in rapid burial and short residence times for sediment near the sea floor and minimizes marine cementation. Therefore, although the Capitan of the Guadalupe Mountains has been described as a 'catch-up' carbonate margin, elsewhere it can be better described as a 'keep-up' margin. Probable causes for the varying progradation rates around the Delaware basin include variations in siliciclastic input, in carbonate production, and in subsidence rates.

  12. Palynology and Stratigraphy of the Nubian Sandstone in Libya and Comparison with Egypt

    NASA Astrophysics Data System (ADS)

    Tekbali, Ali; Hlal, Osama

    2013-04-01

    The so-called "Nubian Sandstone" outcrops along a wide area from Algeria to the Red Sea, forming two regressive phases. The lower phase is represented in Egypt by the Basal Clastic Unit, the Desert Rose Unit, the Abu Ballas Formation and the Matruh Shale. In Libya it is represented by the Mesak Sandstone, Sarir Sandstone, Cabao Sandstone and Kiklah Formation. In both countries, these successions are covered by a carbonate sequence, resulting from the Tethyan transgression during the Cenomanian. In Egypt however, the upper regressive phase is represented by the Taref Sandstone which was deposited during a brief period of active progradation, following the Tethyan incursion. This is not observed in Libya. Comparison of palynological studies in Libya with those documented by several authors in Egypt reveals that the "Nubian" facies in Libya were deposited before equivalent facies in Egypt. The Basal Clastic Unit, dated as Hautrauvian-Barremian, may be equivalent, at least to a part of the Neocomian Cabao Sandstone in NW Libya. Jarmah Member of the Mesak Formation in Libya was dated as Berriasian on the basis of Pilosisporites and Trilobosporites. This makes it older than any "Nubian" unit in Egypt. The Matruh Shale was assigned to the Aptian on the basis of Tricolpites, and the Abu Balls Formation 34 as Aptian-Albian on the basis of Tricolpites and Rousisporites radiatus. Whereas, there is no equivalent to the Aptian in NW Libya, the Aptian-Albian of Egypt is similar to Zone 1 of the Kiklah Formation and As Sarir Sandstone, which were dated as early Albian on the basis of Afropollis spp., and Perotriletes pannuceus, an Albian element not recorded in Egypt. The Plant Beds in southwestern Egypt were dated as Cenomanian on the basis of advanced angiosperm pollen. In Libya, equivalent bodies were considered Vraconian, representing the uppermost Albian, because it lacks Cenomanian pollen (e.g. Tricolpites mutabilis). Comparison of local sea-level changes with global sea

  13. Camorim Field, Brazil: facies and oil qualities controlling reservoir behavior and well performances

    SciTech Connect

    Nascimento, O.S.; Menezes, S.X.; Bandeira, A. Jr.; Pimental, A.M.; Oliveira, C.M.P.

    1982-05-01

    Camorim Field is located offshore Sergipe State, Brazil. The producing section includes 150 M of Cretaceous conglomerates and coarse to very fine-grained sandstones, interbedded with siltstones and shales. Within this interval, 6 pools are recognized based on log correlation and facies analysis. The field has an area of 25 sq km and the reservoir average depth is 1900 m. Twenty-eight development wells were drilled. Reservoir geology and performance were analyzed by a multidisciplinary group. The reservoirs were fully cored in 5 wells and the correlation between rock and log responses allowed facies mapping throughout the field. The depositional model is interpreted as an alluvial-fan complex prograding toward a lacustrine environment.

  14. Areal distribution of sedimentary facies determined from seismic facies analysis and models of modern depositional systems

    SciTech Connect

    Seramur, K.C.; Powell, R.D.; Carpenter, P.J.

    1988-02-01

    Seismic facies analysis was applied to 3.5-kHz single-channel analog reflection profiles of the sediment fill within Muir Inlet, Glacier Bay, southeast Alaska. Nine sedimentary facies have been interpreted from seven seismic facies identified on the profiles. The interpretations are based on reflection characteristics and structural features of the seismic facies. The following reflection characteristics and structural features are used: reflector spacing, amplitude and continuity of reflections, internal reflection configurations, attitude of reflection terminations at a facies boundary, body geometry of a facies, and the architectural associations of seismic facies within each basin. The depositional systems are reconstructed by determining the paleotopography, bedding patterns, sedimentary facies, and modes of deposition within the basin. Muir Inlet is a recently deglaciated fjord for which successive glacier terminus positions and consequent rates of glacial retreat are known. In this environment the depositional processes and sediment characteristics vary with distance from a glacier terminus, such that during a retreat a record of these variations is preserved in the aggrading sediment fill. Sedimentary facies within the basins of lower Muir Inlet are correlated with observed depositional processes near the present glacier terminus in the upper inlet. The areal distribution of sedimentary facies within the basins is interpreted using the seismic facies architecture and inferences from known sediment characteristics proximal to present glacier termini.

  15. Cyclic sedimentation, synsedimentary volcanism, microfabrics, and fracture intensity in the Austin Chalk, Texas

    SciTech Connect

    Hovorka, S.D. )

    1992-01-01

    Pelagic depositional environments of the Austin Chalk (Coniacian-Santonian) were influenced by sea-level variation, planktonic productivity, and allochthonous detrital input. Subtle differences in chalk facies influence fracture intensity, therefore imposing stratigraphic variability on hydrologic properties of the Austin Chalk. Variations in fracture intensity may affect ground-water flow through the Superconducting Super Collider (SSC) site south of Dallas in the same way that they influence hydrocarbon production in South Texas. The lower Austin Chalk was deposited during transgression. Glauconitic sandstone is overlain by cyclic chalk containing chalk-filled channels. Meter-thick chalk/marl cycles have frequencies in the Milankovitch spectrum. Marl accumulated during episodes of decreased planktonic productivity. Maximum flooding is indicated by organic-rich marls in the upper part of the Lower Austin Chalk. Shallowing during deposition of the middle and upper Austin Chalk is indicated by increasing abundance of winnowed lag deposits and firm grounds, resulting in increased faunal diversity. Authigenic clay, a product of alteration of volcanic ash codeposited with the chalk and marl, increases ductility in the middle Austin Chalk. The stratigraphic distribution of authigenic clay corresponds to disseminated biotite, quartz, and feldspar phenocrysts in most samples of the middle Austing Chalk. Authigenic clay decreases porosity, influences porosity-permeability relationships, and provides a regionally traceable low SP log response that correlates with low fracture intensity.

  16. Facies and petrophysical modelling of a thick lower cretaceous tsunami deposit in E Spain: Up-scaling from sample to outcrop scales

    NASA Astrophysics Data System (ADS)

    Veloso, Fernanda M. L.; Liesa, Carlos L.; Soria, Ana R.; Meléndez, Nieves; Frykman, Peter

    2016-08-01

    The tsunami deposit (up to 3 m thick) of the Cretaceous Camarillas Formation in the Galve sub-basin (eastern Spain) is characterized by a large lateral extent (35 km2) and facies uniformity, consisting in fine to coarse subarkosic-arkosic sandstones. At the scale of outcrop observation, different lithofacies were distinguished and related to sedimentation processes. Sand facies distribution conditioned the facies heterogeneity at both mesoscopic or outcrop scales (10- 1-101 m scale) and sample scale (10- 3-10- 2 m). The sample features were up-scaled to that of a facies model using probability functions and variograms as well as to outcrop-scale data (geometry and size) of facies distribution, and it showed a good correlation with the facies distribution at the outcrop. Porosity is strongly correlated to permeability and the pairs of porosity and permeability values fall into the global hydraulic element (GHEs) 5, so that they can be up-scaled into reservoir models in terms of hydraulic properties. From data analysis, no apparent link between sand sorting and porosity and permeability values was observed. The petrophysical models, which were independent of facies models, were up-scaled taking into account the porosity and permeability values from sample data and the statistical analysis of their distribution along the outcrop. The permeability model was carried out as a function of porosity by applying a linear relation, which simplified the modelling process and discarded permeability uncertainties linked to facies distribution in the deposit. In spite of different source data, the petrophysical models show a distribution of lower and higher values that resembles the facies model. Consequently, our modelling results clearly suggest the link of facies type and their grain size distributions with the petrophysical properties into the deposit. Consistency between facies and petrophysical models and outcrop-scale observations make it possible to extrapolate to other

  17. Multidisciplinary studies on ancient sandstone quarries of Western Sardinia (Italy).

    NASA Astrophysics Data System (ADS)

    Grillo, Silvana Maria; Del Vais, Carla; Naitza, Stefano

    2013-04-01

    , Oristano, Santa Giusta). They are prevailing fine-medium grained carbonate sandstones, and subordinate coarse sandstones and micro-conglomerates, variably cemented. In the studied areas, stratigraphic sequences grade from coarser facies of marine environment to fine-grained aeolian deposits, marked by cross-stratification. The Quaternary sedimentary sequence rests on Miocene limestones and clays, and on Plio-Pleistocene basalts. On optical microscopy, sandstones show grain-supported texture, with abundant carbonate bioclasts, intraclasts and algal nodules, with quartz, feldspars and fragments of granitoids, quartzites, volcanics. Grainsize in sandstone sequences progressively decreases towards the top, corresponding to an increase of fine bioclastic components. Terrigenous components change from the northernmost outcrops (Is Arutas quarries), where clasts of granitoid origin are dominant, to the southern outcrops (San Giovanni di Sinis quarries), which show a more marked compositional heterogeneity, with frequent volcanic feldspars and lithoclasts. The calcitic cement also shows distinct variations, both along the stratigraphic sequence and at areal scale, between the sparitic type and the micro/cryptocrystalline type. First evidences on samples from Tharros city walls indicate that sandstone blocks may come, almost in part, from the quarries of San Giovanni di Sinis that, consequently, could have started to work during the Punic age. Other evidences in the area, however, indicate that quarrying activities in Sinis continued well over the Ancient times, presumably including all the Middle Ages.

  18. Operation Sandstone: 1948. Technical report

    SciTech Connect

    Berkhouse, L.H.; Hallowell, J.H.; McMullan, F.W.; Davis, S.E.; Jones, C.B.

    1983-12-19

    SANDSTONE was a three-detonation atmospheric nuclear weapon test series conducted during the spring of 1948 at Enewetak Atoll in the Marshall Islands. Report emphasis is on the radiological safety of the personnel. Available records on personnel exposure are summarized.

  19. Factors controlling reservoir quality in tertiary sandstones and their significance to geopressured geothermal production

    SciTech Connect

    Loucks, R.G.; Richmann, D.L.; Milliken, K.L.

    1981-01-01

    Variable intensity of diagenesis is the factor primarily responsible for contrasting regional reservoir quality of Tertiary sandstones from the upper and lower Texas coast. Detailed comparison of Frio sandstone from the Chocolate Bayou/Danbury Dome area, Brazoria County, and Vicksburg sandstones from the McAllen Ranch Field area, Hidalgo County, reveals that extent of diagenetic modification is most strongly influenced by (1) detrital mineralogy and (2) regional geothermal gradients. The regional reservoir quality of Frio sandstones from Brazoria County is far better than that characterizing Vicksburg sandstones from Hidalgo County, especially at depths suitable for geopressured geothermal energy production. However, in predicting reservoir quality on a site-specific basis, locally variable factors such as relative proportions for porosity types, pore geometry as related to permeability, and local depositional environment must also be considered. Even in an area of regionally favorable reservoir quality, such local factors can significantly affect reservoir quality and, hence, the geothermal production potential of a specific sandstone unit.

  20. CO2 Storage Potential of the Eocene Tay Sandstone, Central North Sea, UK

    NASA Astrophysics Data System (ADS)

    Gent, Christopher; Williams, John

    2017-04-01

    storage scenario. Principal risks include injection-induced pressure-increase limiting injectivity, caused by limited connectivity between sand-rich sequences, up-dip migration to sandstone shelf-facies of the overlying Mousa Formation, or to hydraulically-connected underlying Tertiary sandstones such as the Forties Member which may in places be in hydraulic communication.

  1. Paleoshorelines in the Upper Cretaceous Point Lookout Sandstone, southern San Juan Basin, New Mexico

    USGS Publications Warehouse

    Zech, R.S.

    1982-01-01

    LANDSAT images and aerial photography reveal several parallel linear features as much as 17 km long and 0.7 km wide. Detailed cross sections normal to a linear feature show it to be an exhumed paleoshoreline containing several overlapping sandstone units. Each unit tends to pinchout into the shales of the overlying Menefee Formation, showing a range of depositional environments including upper shoreface, foreshore, washover and eolian. Paleogeomorphic elements, predominately beach ridges and interridge swales, shape the upper surface of the sandstone and produce a relief as great as 4.2 m. The various components found in the paleoshoreline create a trellis-like drainage pattern that contrasts with the regional dendritic drainage pattern; the resulting linear feature is easily discernible on aerial photography and LANDSAT images. The rapid lithologic and thickness changes of the sandstone bodies in these linear features provide excellent potential as stratigraphic trap for hydrocarbons. Paleoshoreline facies are likely to be preserved in areas of thickest marginal marine regressive sand accumulation and similar paleoshoreline systems may be preserved at depth in the Point Lookout (Sandstone) or other Cretaceous sandstones.

  2. Transgressive origin of channeled estuarine deposits in the Point Lookout Sandstone, northwestern New Mexico: A model for Upper Cretaceous, cyclic regressive parasequences of the US Western Interior

    SciTech Connect

    Devine, P.E. )

    1991-06-01

    Regionally correlatable regressions, recorded in Upper Cretaceous strata from the US Western Interior, represent low-order cyclic progradations of the epeiric seaway shoreline. Stratigraphic intertonguing of coastal sandstone deposits and marine shales developed in response to higher order depositional cycles where episodic transgressions interrupt regressions. A simple model based on Walther's Law of Facies has most often been used to interpret these deposits, including channeled estuarine sandstones commonly found at the top of the sequence. The author proposes an alternative explanation for these deposits based on time-stratigraphic architecture and component facies distributions of the Point Lookout Sandstone in the northwestern San Juan basin, New Mexico. Interpretations of outcrop measured sections and well-log correlations suggest an individual parasequence is actually the product of a depositional couplet that includes a regressive phase and a transgressive phase. Strand-plain progradation during the regressive phase produced upward-coarsening, shoreline deposits. Deposition during the transgressive phase occurred mainly in a zone landward of a reworked shoreline trend and comprises a lagoonal-estuarine system. Transgressive estuarine deposits appear to be an important potential reservoir facies in the Point Lookout section. Each estuarine sandstone is developed as a discrete reservoir unit at the landward limit of a parasequence. These sandstones can be correlated into the subsurface and their distribution mapped parallel to depositional strike. The distribution of channeled estuarine reservoirs can be predicted and effectively exploited based on the depositional couplet mode.

  3. Classification of a second group of ordinary chondrites from Texas

    NASA Astrophysics Data System (ADS)

    Ehlmann, A. J.; Keil, K.

    1987-03-01

    Based on optical microscopy and electron microprobe analyses of mafic minerals, six previously undescribed or poorly known ordinary chondrites from Texas were classified into compositional groups, petrologic types, and shock facies. These meteorites are Junction, L5d; Anton, H5b; Venus, H4d; Dalhart, H5a; Rosebud, H5c; and Cranfills Gap, H6c.

  4. Classification of a second group of ordinary chondrites from Texas

    NASA Technical Reports Server (NTRS)

    Ehlmann, Arthur J.; Keil, Klaus

    1987-01-01

    Based on optical microscopy and electron microprobe analyses of mafic minerals, six previously undescribed or poorly known ordinary chondrites from Texas were classified into compositional groups, petrologic types, and shock facies. These meteorites are Junction, L5d; Anton, H5b; Venus, H4d; Dalhart, H5a; Rosebud, H5c; and Cranfills Gap, H6c.

  5. A multistorey sandstone complex in the Himalayan Foreland Basin, NW Himalaya, India

    NASA Astrophysics Data System (ADS)

    Kumar, Rohtash; Sangode, Satish J.; Ghosh, Sumit K.

    2004-07-01

    Ten parallel stratigraphic sections (1500-1800 m thick) spread over an area of >400 km 2 in Dehra Dun sub-basin (DSB) of the Himalayan Foreland Belt (HFB) were studied to understand the anatomy of one of the largest (900-1200 m thick) fluviatile Multistorey Sandstone Complexes (MSC) of the world using fluvial geometry, compositional data and magnetic fabrics over a magnetostratigraphically controlled master section. The multistorey sandstone complex, between 10-5 Ma representing the Middle Siwalik sub-Group, comprises of grey, medium- to fine-grained lithic arenites to lithic greywacke and records tectonic and/or climatic episodes. Three main facies associations are recognised: sandstone-mudstone, sandstone, and conglomerate-sandstone that represent fluvial fan deposit. Palaeocurrent data show radial palaeoflow pattern with major palaeodrainage towards the southern quadrant. The magnetic fabric studies suggest three major tectonic pulses. The first pulse at ˜8.7 Ma resulted in the development of major depocenter for the MSC, the second pulse at ˜7.65 Ma enhanced the sedimentation and progradation, while the third pulse at ˜6.5 Ma records overlapping earlier fluvial fan by another coarse grained piedmont alluvial fan. Thrust movement in the northern fold belt, basement lineaments and rate of basin subsidence controlled the lateral and vertical facies distribution and palaeodrainage. The sedimentation pattern of the multistorey complex is characterised by mainly sheet flood deposits of laterally avulsing unconfined braided rivers and resembles to the modern megafan sedimentation in the Ganga Basin to the south.

  6. Areal distribution of sedimentary facies determined from seismic facies analysis and models of modern depositional systems

    SciTech Connect

    Seramur, K.C.; Powell, R.D.; Carpenter, P.J.

    1988-01-01

    Seismic facies analysis was applied to 3.5-kHz single-channel analog reflection profiles of the sediment fill within Muir Inlet, Glacier Bay, southeast Alaska. Nine sedimentary facies have been interpreted from seven seismic facies identified on the profiles. The interpretations are based on reflection characteristics and structural features of the seismic facies. The following reflection characteristics and structural features are used: reflector spacing, amplitude and continuity of reflections, internal reflection configurations, attitude of reflection terminations at a facies boundary, body geometry of a facies, and the architectural associations of seismic facies within each basin. The depositional systems are reconstructed by determining the paleotopography, bedding patterns, sedimentary facies, and modes of deposition within the basin. Muir Inlet is a recently deglaciated fjord for which successive glacier terminus positions and consequent rates of glacial retreat are known. In this environment the depositional processes and sediment characteristics vary with distance from a glacier terminus, such that during a retreat a record of these variations is preserved in the aggrading sediment fill. Sedimentary facies within the basins of lower Muir Inlet are correlated with observed depositional processes near the present glacier terminus in the upper inlet.

  7. Texas Greenup

    NASA Technical Reports Server (NTRS)

    2007-01-01

    June 2007 was one of the wettest Junes on record for the state of Texas. Starting in late May, a string of low-pressure systems settled in over the U.S. Southern Plains and unleashed weeks of heavy to torrential rain. During the final week of June, much of Texas, Oklahoma, and Kansas received more than 330 percent of their average rainfall, said the National Climatic Data Center. The widespread heavy rain brought deadly floods to the entire region. On July 6, the Associated Press reported that every major river basin in Texas was at flood stage, an event that had not occurred since 1957. In addition to causing floods, the rains stimulated plant growth. The grassy, often arid, plains and plateaus of northern Mexico (bottom left), Texas (center), and New Mexico (top, left of center) burst to life with dense vegetation as this vegetation anomaly image shows. Regions where plants were growing more quickly or fuller than average are green, while areas where growth is below average are brown. Most of Texas is green, with a concentrated deep green, almost black, spot where vegetation growth was greatest. This area of western Texas is where the Pecos River flows out of New Mexico and heads southeast to the Rio Grande. In the darkest areas, vegetation was more than 100 percent above average. The brown spots in northeastern Texas and Oklahoma (top, right of center) may be areas where persistent clouds or water on the ground are hiding the plants from the satellite's view. Plants may also be growing less than average if swamped by too much rain. The image was made with data collected by the SPOT satellite between June 11 and June 20, 2007. NASA imagery created by Jesse Allen, Earth Observatory, using SPOT data provided courtesy of the USDA Foreign Agricultural Service and processed by Jennifer Small and Assaf Anyamba of the GIMMS Group at NASA GSFC.

  8. Facies transition and depositional architecture of the Late Eocene tide-dominated delta in northern coast of Birket Qarun, Fayum, Egypt

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, Zaki A.

    2016-07-01

    Late Eocene successions in the Fayum Depression display notable facies transition from open-marine to brackish-marine realms. Stratigraphic and sedimentologic characteristics of the depositional facies are integrated with ichnological data for the recognition of four facies associations (FA1 to FA4). The transition from open-marine sandstones (FA1) to the brackish-marine deposits (FA2) heralds a transgressive - regressive dislocation. The shallowing- and coarsening-upward progradation from the basal prodelta mudstone-dominated facies (FA2a) to deltafront heterolithics (FA2b) and sandstone facies (FA2c) are overlain by finning-upward delta plain deposits which are expressed by the delta plain mudstone (FA2d) and erosive-based distributary channel fills (FA4). Prodelta/deltfront deposits of FA2 are arranged in thinning- and coarsening-upward parasequences which are stacked in a shallowing-upward progressive cycle. Shallow-marine fossiliferous sandstones (FA3) mark the basal part of each parasequence. Stratigraphic and depositional architectures reflect a tide-dominated delta rather than an estuarine and incised valley (IV) model. This can be evinced by the progressive facies architecture, absence of basal regional incision or a subaerial unconformity and the stratigraphic position above a maximum flooding surface (MFS), in addition to the presence of multiple tidally-influenced distributary channels. Stratigraphic and depositional characteristics of the suggested model resemble those of modern tide-dominated deltaic systems. Accordingly, this model contributes to our understanding of the depositional models for analogous brackish-marine environments, particularly tide-dominated deltas in the rock record.

  9. Polygonal deformation bands in sandstone

    NASA Astrophysics Data System (ADS)

    Antonellini, Marco; Nella Mollema, Pauline

    2017-04-01

    We report for the first time the occurrence of polygonal faults in sandstone, which is compelling given that layer-bound polygonal fault systems have been observed so far only in fine-grained sediments such as clay and chalk. The polygonal faults are dm-wide zones of shear deformation bands that developed under shallow burial conditions in the lower portion of the Jurassic Entrada Fm (Utah, USA). The edges of the polygons are 1 to 5 meters long. The shear deformation bands are organized as conjugate faults along each edge of the polygon and form characteristic horst-like structures. The individual deformation bands have slip magnitudes ranging from a few mm to 1.5 cm; the cumulative average slip magnitude in a zone is up to 10 cm. The deformation bands heaves, in aggregate form, accommodate a small isotropic horizontal extension (strain < 0.005). The individual shear deformation bands show abutting T-junctions, veering, curving, and merging where they mechanically interact. Crosscutting relationships are rare. The interactions of the deformation bands are similar to those of mode I opening fractures. Density inversion, that takes place where under-compacted and over-pressurized layers (Carmel Fm) lay below normally compacted sediments (Entrada Sandstone), may be an important process for polygonal deformation bands formation. The gravitational sliding and soft sediment structures typically observed within the Carmel Fm support this hypothesis. Soft sediment deformation may induce polygonal faulting in the section of the Entrada Sandstone just above the Carmel Fm. The permeability of the polygonal deformation bands is approximately 10-14 to 10-13 m2, which is less than the permeability of the host, Entrada Sandstone (range 10-12 to 10-11 m2). The documented fault networks have important implications for evaluating the geometry of km-scale polygonal fault systems in the subsurface, top seal integrity, as well as constraining paleo-tectonic stress regimes.

  10. Facies control on seismites in an alluvial-aeolian system: The Pliocene dunefield of the Teruel half-graben basin (eastern Spain)

    NASA Astrophysics Data System (ADS)

    Liesa, Carlos L.; Rodríguez-López, Juan Pedro; Ezquerro, Lope; Alfaro, Pedro; Rodríguez-Pascua, Miguel Ángel; Lafuente, Paloma; Arlegui, Luis; Simón, José L.

    2016-10-01

    The recognition of seismically induced soft-sediment deformation structures (SSDS) in sedimentary successions characterized by different facies, and hence by different rheology, is challenging. This is the case for high porosity and high permeability aeolian facies interbedded with muddy wet interdune deposits and alluvial conglomerates and sandstones. Several types of SSDS have been studied in two exposures of the Upper Pliocene (2.9-2.6 Ma) sediments of a fault-bounded intracontinental aeolian dune field in the Teruel Basin (Iberian Chain, eastern Spain). Among SSDS, load and fluid-escape structures, apart from several animal tracks, have been recognized. Those structures show an irregular distribution through the studied stratigraphic sections, being scarce in homogenous aeolian sands and frequent in water-related facies. A detailed study of the distribution and geometry of SSDS and their relationships with respect to the stratigraphic architecture and facies has allowed a critical discrimination of trigger mechanisms, i.e. biological or physical overloading vs. earthquakes. The seismically induced structures are concentrated into seven deformed beds, showing an uneven lateral distribution and geometry closely controlled by the hosting sedimentary facies and their rheology. These seismites resulted from liquefaction during moderate earthquakes (estimated magnitude from 5.0 to 6.8). The most probable seismogenic source was the Sierra del Pobo normal fault zone, located 2 km to the East. Results show how an appropriate recognition of sedimentary facies is crucial to understand the lateral variability of seismites in sedimentary environments characterized by sharp facies changes.

  11. Tectonic and eustatic controls on facies distribution in the middle of upper Jurassic, Viking Graben, Norwegian North Sea

    SciTech Connect

    Sneider, J.S.; Vail, P.R. ); De Clarens, P. )

    1993-09-01

    The Middle of Upper Jurassic in the Viking Graben area was deposited during an overall transgression. From the lower Toarcian to the base of the cretaceous, there are seven 2nd-order (3-5 m.y.) transgressive-regressive (T/R) facies cycles that are related to regional tectonic events. These cycles dominate facies distribution, appear synchronous, and can be correlated throughout the study area. Local tectonics and sediment supply can modify these cycles. Local tectonics, sediment supply, and position in the T/R facies cycles control development of 3rd-order (0.5-3 m.y.) cycles. Where sediment supply is low, 3rd-order sequences are poorly developed. During a 2nd-order regression, shelfal areas and local highs are often eroded. Third-order sequences have well developed lowstands system-Y tracts (LST) and poorly developed transgressive systems tracts (TST). During 2nd-order transgressions, 3rd-order sequences have enhanced TST, starved HST, and poorly developed LST. Thick, stacked, shoreface sandstones may develop in the TST on terraces or on gently dipping slopes if sediment supply is high. The base of these sequences often shows an abrupt basinward shift in facies followed by backstepping facies. turbidites develop during 3rd-order lowstands when there is a steeply dipping slope and high sediment supply, but their distribution is more limited.

  12. Reservoir characterization and modeling of deltaic facies, Lower Wilcox, Concordia Parish, Louisiana

    SciTech Connect

    Schenewerk, P.; Goddard, D.; Echols, J. |

    1994-09-01

    Production decline in several fields in Concordia Parish, Louisiana, has sparked interest in the economic feasibility of producing the remaining bypassed oil in the lower Wilcox. One of these fields, the Bee Brake field, located in townships 4N, 6E and 4N, 7E, has been one of the more prolific oil-producing areas in east central Louisiana. The producing interval in the field, the Minter, typically consists of an upper Bee Brake sand and a lower Angelina sand. Cumulative production from the Angelina has been 2.1 mm STB of oil. A detailed study of a conventional core in the center of the field presented a 15-ft-thick Minter interval bounded above and below by sealing shales and lignites of lower delta plain marsh facies. The lower oil producing 3-ft thick Angelina consists of fine to medium sandstone of overbank bay fill facies. The upper 4-ft thick Bee Brake is a very fine silty sandstone with characteristics of a crevasse splay deposit. Special core analysis data (capillary pressure, relative permeability, and waterflood recovery) were obtained and have been used to develop a simulation model of the two reservoirs in the Minter. This model incorporates the geologic and engineering complexities noted during the first comprehensive evaluation of the field area. The model results will be used by the operators in the field to plan the optimal development for enhanced recovery. In addition, the production potential of the Bee Brake sand has been defined.

  13. Kamafugitic diatremes: facies characterisation and genesis—examples from the Goiás Alkaline Province, Brazil

    NASA Astrophysics Data System (ADS)

    Junqueira-Brod, Tereza Cristina; Brod, José Affonso; Gaspar, José Carlos; Jost, Hardy

    2004-09-01

    This paper describes the internal organisation of two diatremes (Águas Emendadas and Neuzinha) and one small breccia-filled conduit (Tigre) in the central portion of the Late Cretaceous Goiás Alkaline Province (GAP), central Brazil, and explores the criteria for facies recognition. The GAP kamafugitic diatremes are emplaced into Carboniferous sandstones of the Aquidauana Formation, at the northern margin of the Paraná Basin. They are usually elliptical structures, not longer than 900 m, filled with breccia and partially covered by thin kamafugitic to basanitic lava flows. The breccias are dominated by juvenile pyroclasts, with subordinate amounts of cognate fragments and xenoliths. In addition to variations in ash and lapilli proportions, juvenile fragment types may be used to discriminate genetic processes and the corresponding pyroclastic deposits. An extensive field, textural and compositional dataset was analysed by multivariate statistical techniques. Combined with field observations, this allowed us to define a set of facies for kamafugitic diatremes, and, more importantly, to understand the internal structure of the studied bodies and to cross-correlate them. Seven distinct facies were recognised. The Fluidised Conduit Facies (FCF) represents high-energy, strongly fluidised but only moderately fragmented systems. It occurs in a confined environment, and is typical of deeper parts of the conduit, before the actual diatreme level is reached by the ascending fluidised magma. Large amounts of spinning droplets are formed within this region. The Fluidised Conduit-Diatreme Facies (FCDF) is characteristic of intermediate depths in the conduit, where highly fluidised and highly fragmented systems produce large amounts of ash. Spinning droplets decrease in abundance, ordinary juvenile fragments become very common, and xenoliths from the country rock in the immediate vicinity of the diatreme are present. The Fluidised Fragmented Facies (FFF) and the Magmatic

  14. Mid-Eocene alluvial-lacustrine succession at Gebel El-Goza El-Hamra (Shabrawet area, NE Eastern Desert, Egypt): Facies analysis, sequence stratigraphy and paleoclimatic implications

    NASA Astrophysics Data System (ADS)

    Wanas, H. A.; Sallam, E.; Zobaa, M. K.; Li, X.

    2015-11-01

    This study aims to provide the depositional facies, sequence stratigraphic and paleoclimatic characteristics of the Mid-Eocene (Bartonian) continental succession exposed at Gebel El-Goza El-Hamra (Shabrawet Area, NE Eastern Desert, Egypt). The studied succession consists of siliciclastic rocks followed upward by carbonate rocks. Detailed field observation and petrographic investigation indicate accumulation in floodplain-dominated alluvial and shallow lacustrine systems. The floodplain-dominated alluvial facies (45 m thick) is composed mainly of carbonate nodules-bearing, mottled mudrock with subordinate sandstone and conglomerate beds. The conglomerate and pebbly sandstone bodies interpreted as ephemeral braided channel deposits. The massive, laminated, planner cross-bedded, fine- to medium-grained sandstone bodies interlayered within mudstone reflect sheet flood deposits. The mudrocks associated with paleosols represent distal floodplain deposits. The shallow lacustrine facies (15 m thick) is made up of an alternation of marlstone, micritic limestone, dolostone and mudrock beds with charophytes and small gastropods. Both the alluvial and lacustrine facies show evidence of macro-and micro-pedogenic features. Pollen assemblages, stable δ18O and δ13C isotopes, and paleopedogenic features reflect prevalence of arid to semi-arid climatic conditions during the Bartonian. The sequence stratigraphic framework shows an overall fining-upward depositional sequence, consisting of Low- and High-accommodation Systems Tracts (LAST, HAST), and is bounded by two sequence boundaries (SB-1, SB-2). Conglomerate and pebbly sandstone deposits (braided channel and sheet flood deposits) of the lower part of the alluvial facies reflect a LAST. Mudrock and silty claystone facies (distal floodplain deposits) of the upper part of alluvial facies and its overlying lacustrine facies correspond to a HAST. The LAST, HAST and SB were formed during different accommodation-to-sediment supply (A

  15. Attribute classification for generating GPR facies models

    NASA Astrophysics Data System (ADS)

    Tronicke, Jens; Allroggen, Niklas

    2017-04-01

    Ground-penetrating radar (GPR) is an established geophysical tool to explore near-surface sedimentary environments. It has been successfully used, for example, to reconstruct past depositional environments, to investigate sedimentary processes, to aid hydrogeological investigations, and to assist in hydrocarbon reservoir analog studies. Interpreting such 2D/3D GPR data, usually relies on concepts known as GPR facies analysis, in which GPR facies are defined as units composed of characteristic reflection patterns (in terms of reflection amplitude, continuity, geometry, and internal configuration). The resulting facies models are then interpreted in terms of depositional processes, sedimentary environments, litho-, and hydrofacies. Typically, such GPR facies analyses are implemented in a manual workflow being laborious and rather inefficient especially for 3D data sets. In addition, such a subjective strategy bears the potential of inconsistency because the outcome depends on the expertise and experience of the interpreter. In this presentation, we investigate the feasibility of delineating GPR facies in an objective and largely automated manner. Our proposed workflow relies on a three-step procedure. First, we calculate a variety of geometrical and physical attributes from processed 2D and 3D GPR data sets. Then, we analyze and evaluate this attribute data base (e.g., using statistical tools such as principal component analysis) to reduce its dimensionality and to avoid redundant information, respectively. Finally, we integrate the reduced data base using tools such as composite imaging, cluster analysis, and neural networks. Using field examples that have been acquired across different depositional environments, we demonstrate that the resulting 2D/3D facies models ease and improve the interpretation of GPR data. We conclude that our interpretation strategy allows to generate GPR facies models in a consistent and largely automated manner and might be helpful in

  16. Sequence stratigraphy and depositional facies of the Silurian-Devonian interval of the northern Permian basin

    SciTech Connect

    Canter, K.L.; Geesaman, R.C. ); Wheeler, D. )

    1992-04-01

    The Silurian and Devonian intervals of the northern Central Basin platform area of west Texas and southeastern New Mexico include the Fusselman, Wristen, and Thirtyone formations and the Woodford Shale. The carbonate-rich Fusselman, Wristen, and Thirtyone formations record a transition from ramp to platform deposition. Oolite grainstones of the lower Fusselman Formation were deposited in a ramp setting during an Upper Ordovician/Lower Silurian transgression. The overlying crinoid packstones and grainstones represent shoals that developed along a break in slope separating the evolving platform from a southward-dipping starved basin. By the close of Fusselman deposition, the platform was well developed, with shallow peridtidal mudstones and wackestones, and high-energy grainstones deposited as near-parallel facies tracts over the platform area. The platform system became fully developed during the deposition of the Wristen Formation. Porous dolomitic peridtidal and platform margin facies grade downdip into nonporous, limy and argillaceous open-shelf facies. Platform facies are typified by numerous shallowing-upward parasequences that terminated at subaerial exposure surfaces. The rocks of the Lower Devonian Thirtyone Formation were deposited as a wedge that onlaps the exposed Silurian platform margin. This formation contains a porous, chert-rich, lowstand deposit; a transgressive disconformity; and variably porous, grain-rich highstand deposits representing an overall sea level rise. A major unconformity marks the contact between the karsted upper surface of the Thirtyone Formation and the overlying organic-rich, anoxic Woodford Shale.

  17. Influence of high-frequency strandline cycles on internal reservoir geometry: Point Lookout sandstone, New Mexico and Colorado

    SciTech Connect

    Wright, R.

    1989-03-01

    High-frequency (< 100,000 years) transgressive-regressive strandline couplets that form basic building blocks of individual marine shoreface sandstones strongly influence strandline migration pattern and internal reservoir geometry. At reservoir scale, couplets average 7-10 m thick and are characterized by repetitive stacking of genetically related sandstone-mud rock packages. Individual cycles, or architectural elements, correlate in 3-D outcrop for at least 30 km, are locally bundled into larger discrete packages of five to eight constituent cycles, and are distinguishable in well logs. Contrary to long-held opinion, many of these cycles are not asymmetric. Rather, they contain thin (< 3 m) transgressive systems tracts that are overlain by thicker (< 7 m) regressive systems tracts and which are separated from one another by a pronounced downdip surface. Transgressive mud rocks fine upward from siltstone to clay-shale and coarsen landward less than 10 km into thinly interbedded sandstones with abundant siderite lags. Regressive mud rocks coarsen upward and landward into prograding shoreface sandstones that may overlie transgressive sandstones in proximal positions. Landward facies transitions within transgressive and regressive components of a single cycle vary, resulting in complex lithofacies interlayering. The significance for reservoir studies is that repeated transgressive systems tracts form predictable intraformational stratigraphic markers which may influence both horizontal and vertical fluid migration pathways. Importantly, the standard vertical profile fails to properly interpret transgressive deposits (especially sandstones) in the absence of a well-constrained lateral model.

  18. Assessing Biogenecity of Stromatolites: Return to the Facies

    NASA Astrophysics Data System (ADS)

    Shapiro, R. S.; Jameson, S.; Rutter, A.; McCarthy, K.; Planavsky, N. J.; Severson, M.

    2013-12-01

    The discovery of richly microfossiliferous cherty stromatolites near Schreiber and Kakabeka Falls, Ontario, in the 1.9 Ga Gunflint Iron Formation, firmly established the field of pre-Cambrian paleontology. In the half-century since this discovery, paradigm shifts in the ecology of the microfossils as well as the utility of stromatolites as biological markers has caused a re-evaluation of our understanding of the pre-Cambrian fossil record. This research summarizes facies evaluation of the two stromatolite marker beds in the Gunflint-correlative Biwabik Iron Formation of Minnesota. The centimeter-scale microstratigraphy of cores drilled through the central and eastern Mesabi Iron Range was coupled with field descriptions of outcrops and mines in both the Biwabik and Gunflint iron formations. Eight lithologic facies associated with the stromatolites are identified: A) Pebble conglomerate clasts ranging in size of 0.5-3 cm, syneresis cracks, and septarian nodules with medium to coarse grain matrix; B) siltstone with subparallel sub-mm to 5 cm magnetitic and non-magnetic bands; C) stromatolitic boundstone comprising stratiform, pseudocolumnar, domal, undulatory, flat-laminated, dendritic, columnar, and mico-digitate forms and oncoids 0.5 to 2 cm diameter; D) grainstone with medium to coarse siliceous and carbonate ooids and peloids; E) massive green crystalline beds with bands of magnetite, quartz, calcite, disseminated pyrite and localized ankerite; F) autobreccicated fabric of 0.3 to 10 mm clasts; G) medium to coarse sandstone; H) quartzite. Correlation between 11 cores near Hoyt Lakes and 9 cores through the basal stromatolite layer at the MinnTac Mine near Virginia revealed that stromatolites formed both on conglomerate and medium quartz sandstone. Multiple forms of stromatolite may occur in a vertical succession (flat-laminated to undulatory to psuedocolumnar to columnar) or a core may be dominated by one type, typically columnar-stratiform. Where stromatolites do

  19. Depositional sequences and facies in the Torok Formation, National Petroleum Reserve, Alaska (NPRA)

    USGS Publications Warehouse

    Houseknecht, David W.; Schenk, Christopher J.

    2002-01-01

    rates of subsidence accommodated the deposition of a "foredeep clinoform wedge" that contains a high proportion of sand-rich LST deposits. In northern NPRA, lower rates of subsidence favored the accumulation of mud-rich HST deposits. The most favorable stratigraphic trapping geometries in the Torok Formation occur where amalgamated sandstones deposited in turbidite channels incised on the mid- to lower-slope and on the proximal parts of submarine fans during regression (LSTs) are capped by relatively condensed mudstone facies deposited during transgression (TSTs). Common successions observed in Torok cores include a spectrum of slope and turbidite facies. Upper slope facies comprise laminated mudstones and siltstones that locally display evidence of slumping, sliding, and chaotic failure. Lower slope facies comprise heterolithic turbidites at some locations and interlaminated mudstones and thin, very fine-grained sandstones at others. Torok turbidites include amalgamated sandstones deposited in channel systems as well as thin-bedded, widespread sandstones deposited by unconfined flows on lobes or in channel overbank settings. These turbidite facies likely occur in both channel-lobe systems and slope apron systems within the Torok.

  20. Facies distribution, depositional environment, and petrophysical features of the Sharawra Formation, Old Qusaiba Village, Central Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Abbas, Muhammad Asif; Kaminski, Michael; Umran Dogan, A.

    2016-04-01

    moderate-scale transgressive episodes, while the thin shale interbeds in the middle and upper part of the Sharawra Formation represent small-scale transgressions. Overall, the Sharawra Formation contains a series of repetitive transgressive and regressive events and has been interpreted as a pro-deltaic deposit in previous studies. In the present study, the lowermost sandstone thickly bedded facies lie within the transition zone environment. The siltstone facies and the horizontally stratified facies show a middle shore face environment. The middle shore face environment is present locally. The bioturbation in the uppermost facies is indicative of the upper shore face environment. The porosity values do not vary much, as the average porosity for the sandstone facies is about 15%, for the siltstones it ranges about 7%. The permeability is variable throughout the formation, the values range from 50 to 300 md. Although sandstone has a good porosity and permeability, the siltstone facies exhibit poor petrophysical characteristics. In terms of reservoir characterization, the mineralogical mature, moderately well sorted top most sandstone facies, with appreciable porosity and permeability can be considered as a potential reservoir rock. This study has provided a base for future quantitative studies in this important formation in the area.

  1. Reservoir heterogeneity in the middle Frio Formation: Case studies in Stratton and Agua Dulce fields, Nueces County, Texas

    SciTech Connect

    Kerr, D.R. )

    1990-09-01

    Selected middle Frio (Oligocene) reservoirs of Stratton field and the contiguous Agua Dulce field are being studied as part of a Gas Research Institute/Department of Energy/State of Texas cosponsored program designed to improve reserve growth in mature gas fields. Over the past four decades, Stratton has produced 2.0 tcf of gas from 113 middle Frio reservoirs, and Agua Dulce has produced 1.6 tcf from 116 reservoirs. Recent drilling and workover activities, however, suggest the presence of additional untapped or bypassed middle Frio reservoirs. Four reservoirs, the E18/6,020-ft, E21/6,050-ft, E31/6,100-ft, and E41/Bertram, were evaluated over a 13,000-acre tract that includes areas adjacent to both fields. The middle Frio is composed of sand-rich channel-fill and splay deposits interstratified with floodplain mudstones, all forming part of the Gueydan fluvial system. Channel-fill deposits are 30 ({plus minus}15) ft thick and 2,500 ({plus minus}500) ft wide. Splay deposits are up to 30 ft thick proximal to channels and extend as much as 2 mi from channels. Channel-fill and associated splay sandstones are reservoir facies (porosity 20%; permeability = 10s to 100s md); floodplain mudstones and levee sandy mudstones are barriers to flow facies separating individual reservoirs vertically and laterally. The E41/Bertram reservoir is an example of a laterally stacked channel system deposited during relatively slow aggradation. This reservoir includes sand-on-sand contacts and is composed of mostly leaky compartments. The E 18/6,020-ft, E21/6,050-ft, and E31/6,100ft reservoirs are examples of vertically stacked channel systems reflecting higher rates of aggradation. Vertically stacked architectures are more favorable for isolated compartments and therefore are better candidates for infield reserve growth.

  2. Sedimentary facies and environmental ichnology of a ?Permian playa-lake complex in western Argentina

    USGS Publications Warehouse

    Zhang, G.; Buatois, L.A.; Mangano, M.G.; Acenolaza, F.G.

    1998-01-01

    A moderately diverse arthropod icnofauna occurs in ?Permian ephemeral lacustrine deposits of the Paganzo Basin that crop out at Bordo Atravesado, Cuesta de Miranda, western Argentina. Sedimentary successions are interpreted as having accumulated in a playa-lake complex. Deposits include three sedimentary facies: (A) laminated siltstone and mudstone: (B) current-rippled cross-laminated very fine grained sandstone: and (C) climbing and wave-rippled cross-laminated fine-grained sandstone deposited by sheet floods under wave influence in the playa-lake complex. Analysis of facies sequences suggests that repeated vertical facies associations result from transgressive regressive episodes of variable time spans. The Bordo Atravesado ichnofauna includes Cruziana problematica, Diplocraterion isp., cf. Diplopadichnus biformis, Kouphichnium? isp., Merostomichnites aicunai, Mirandaichnium famatinense, Monomorphichnus lineatus, Palaeophyeus tubularis, Umfolozia sinuosa and Umfolozia ef. U. longula. The assemblage is largely dominated by arthropod trackways and represents an example of the Scoyenia ichnofacies. Trace fossils are mostly preserved as hypichnial ridges on the soles of facies C beds, being comparatively rare in facies A and B. Ichnofossil preservation was linked to rapid influx of sand via sheet floods entering into the lake. Four taphonomic variants (types 1-4) are recognized, each determined by substrate consistency and time averaging. Type 1 is recorded by the presence of low density assemblages consisting of poorly defined trackways, which suggests that arthropods crawled in soft, probably slightly subaqueous substrates. Type 2 is represented by low to moderate density suites that include sharply defined trackways commonly associated with mud cracks, suggesting that the tracemakers inhabited a firm, desiccated lacustrine substrate. Type 3 displays features of types 1 and 2 and represents palimpsestic bedding surfaces, resulting from the overprint of terrestrial

  3. Enigmatic eight-meter trace fossils in the Lower Pennsylvanian Lee sandstone, central Appalachian basin, Tennessee

    USGS Publications Warehouse

    Wnuk, C.; Maberry, J.O.

    1990-01-01

    Enigmatic tubular trace fossils up to eight meters long occur in the Lower Pennsylvanian Middlesboro Member of the Lee Formation. Two morphotypes occur: type 1 trace fossils are plain, smooth, vertical, nonbranching, parallel-walled, tubular structures, type 2 trace fossils branch, have walls with faint vertical striations, regularly or irregularly spaced nodes, and funnel-shaped terminations. Sandstone casts filling type 2 structures have helical spiral morphology, and, in rare individuals, faint meniscate fills have been observed. Both trace-fossil morphotypes have poorly cemented wall linings containing framboidal pyrite, amorphous carbon, quartz sand, and poorly preserved fecal material. The trace fossils occur in a massive, structureless, channel-form sandstone, originating at the contact between a channel lag and the overlying massive fill representing a barrier island transgressing an estuarine facies. Origin of these structures is uncertain. -from Authors

  4. A subsurface study of the Denkman sandstone member, Norphlet Formation, hatters Pond field, Mobile County, Alabama

    SciTech Connect

    Young, L.M.; Anderson, E.G.; Baria, L.R. ); Higginbotham, R.S.

    1990-09-01

    Hatters Pond field is in east-central Mobile County in southwestern Alabama and it produces from both the Norphlet and Smackover formations. The structural trap involves salt movement along the west side of the Mobile Fault System that resulted in a faulted salt anticline. The Norphlet Formation of southwestern Alabama consists of red to gray siltstone and pinkish to gray sandstone with conglomerate layers. Three facies have been distinguished within the Norphlet Formation: a lower shale, a red siltstone sequence, and an upper quartzose unit. The thickness of the formation ranges from a feather edge to more than 800 ft (234.8 m) in southwestern Alabama. The Upper Jurassic Denkman Sandstone Member of the Norphlet Formation at Hatters Pond field is a medium- to fine-grained, well-sorted arkosic sandstone between the underlying Norphlet redbed lithofacies and the carbonates of the overlying Smackover Formation. Here, the Denkman Member can be subdivided into a massive upper unit and a low- to high-angle cross-stratified lower unit. The sandstones are quartz-rich with a high percentage of feldspars. The majority of the feldspar grains observed are potassium feldspar. Microcline is usually less altered when compared with other types of feldspar grains. The major types of feldspar replacement include illitization, hematitization, dolomitization, chloritization, calcitization, vacuolization, and anhydritization. Carbonate replacement of feldspars is very abundant, mostly by ferroan dolomite. Rock fragments are not abundant in the Denkman Member, although there is good evidence of a metamorphic/volcanic source area. The sandstones are cemented by dolomite, calcite, anhydrite, and quartz and feldspar overgrowths. The lower Denkman unit is slightly more porous than the upper Denkman unit. The pore-lining authigenic clay, illite, greatly reduces permeability and porosity in these sandstones.

  5. Tide-influenced sedimentary environments and facies

    SciTech Connect

    De Boer, P.L.; Van Gelder, A.; Nio, S.D.

    1988-01-01

    This volume contains examples of recent as well as fossil tide-influenced sedimentary facies. Studies of recent tidal processes and sediments provide an insight into the way in which tidal facies and sequences develop, and into the processes which are active. The studies performed on fossil rocks give information on one-to-one scale model experiments that have been executed by nature both relatively recently and in the distant past. In this work, the parallel presentation of papers on recent and fossil examples of tide-influenced sedimentary facies and environments follows the philosophy of comparative sedimentology, aiming at an understanding of both the past and the present, with the aim also, of forecasting future developments.

  6. Sequence stratigraphy and onlap relationships of a stratigraphic trap, Lower Cretaceous Muddy Sandstone, Hilight field, Powder River basin, Wyoming

    SciTech Connect

    Wheeler, D.M.; Gustason, E.R. )

    1989-09-01

    In Hilight field more than 74 million bbl of oil and 244 bcf of gas have been produced from thin fluvial and shallow marine sandstones of the Lower Cretaceous Muddy Sandstone. In this area the Muddy was deposited during a late Albian sea level rise and onlaps a lowstand subaerial surface of erosion including a dendritic valley system incised into the underlying Skull Creek Shale. Transgressive valley-fill deposits of the Muddy Sandstone in the Hilight field area consist of four regionally correlative, time-bounded, back-stepping, progradational units. The retrogradational nature of these units indicates they belong in a transgressive systems tract rather than a lowstand wedge, as is often implied for valley-fill sequences. Each unit is capped by a regionally extensive marine flooding surface. The contact between units is placed at the surface representing maximum flooding or at the correlative horizon landward of the maximum transgression. Two of these contacts include thin bentonite beds which substantiate the time-stratigraphic interpretation. Petroleum is trapped in each unit by the onlap of reservoir sandstone facies against the lowstand surface of erosion on the impermeable Skull Creek Shale. Top seals are formed by mudstones at the base of overlying units or by the Shell Creek Shale, which overlies the Muddy Sandstone above a regionally extensive marine flooding surface. Reservoir heterogeneity is explained by lateral facies changes within each unit. The lateral and vertical distribution of reservoir-quality sandstone in the Muddy sequence in this area can be used as a model to predict occurrences in similar sequences elsewhere.

  7. Pore-throat sizes in sandstones, tight sandstones, and shales

    USGS Publications Warehouse

    Nelson, Philip H.

    2009-01-01

    Pore-throat sizes in silidclastic rocks form a continuum from the submillimeter to the nanometer scale. That continuum is documented in this article using previously published data on the pore and pore-throat sizes of conventional reservoir rocks, tight-gas sandstones, and shales. For measures of central tendency (mean, mode, median), pore-throat sizes (diameters) are generally greater than 2 μm in conventional reservoir rocks, range from about 2 to 0.03 μm in tight-gas sandstones, and range from 0.1 to 0.005 μm in shales. Hydrocarbon molecules, asphaltenes, ring structures, paraffins, and methane, form another continuum, ranging from 100 Å (0.01 μm for asphaltenes to 3.8 A (0.00038 μm) for methane. The pore-throat size continuum provides a useful perspective for considering (1) the emplacement of petroleum in consolidated siliciclastics and (2) fluid flow through fine-grained source rocks now being exploited as reservoirs.

  8. Facies composition calculated from the sonic, neutron, and density log suite, upper part of the Minnelusa Formation, Powder River basin, Wyoming

    USGS Publications Warehouse

    Schmoker, J.W.; Schenk, C.J.

    1988-01-01

    Sandstones and dolomites of the Permian upper part of the Minnelusa Formation are treated here as four-component systems consisting of fluid-filled pore space, quartz, dolomite, and anhydrite. Response equations of sonic, neutron, and density logs form a system of four simultaneous equations. With four equations and four unknowns, the composition of upper Minnelusa facies is defined by the three-log suite and can be calculated by solving a 4 ?? 4 matrix. Such calculations of facies composition help in establishing subsurface correlations and yield information on the diagenesis and physical character of upper Minnelusa sandstones and dolomites. Applications of composition calculations are illustrated by examples drawn from the area of the West Mellott field (T52N, R68W), where the upper Minnelusa is at depths of about 7000 ft (2100m). -from Authors

  9. The Paleozoic sandstones in Wadi Feiran - El Tor area, Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Allam, A.

    The Paleozoic sandstone succession between Wadi Feiran and El-Tor in southwestern Sinai has been subdivided into five distinct lithostratigraphic units: the Lower Cambrian Araba Formation; the Upper Cambrian Naqus Formation; the Lower Carboniferous Abu Durba Formation; the Upper Carboniferous Aheimer Formation and the Permian Qiseib Formation. The present study has also proved that the Paleozoic Earth movements have undergone distinct changes in the sedimentary facies, together with lateral variations in the composition and thickness of strata. The distribution of the sediments and their faunal contents point to the existence of five major phases of sedimentation during the Paleozoic Era.

  10. The Manciano Sandstone: a shoreface deposit of Miocene basins of the Northern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Martini, I. P.; Cascella, A.; Rau, A.

    1995-09-01

    Well exposed, diamond-line cut, quarry-exposures of the Manciano Sandstone allow a detailed analysis of sandy, fossiliferous, nearshore deposits of the shelf of the Northern Apennines. The Manciano Sandstone is characterized by medium to very coarse, washed, fairly well sorted, lithic sandstone, with thin interlayers of sandy conglomerates. It displays two principal, rhythmically alternating sandy facies: (a) slightly burrowed (mostly Macaronichnus, Ophiomorpha, Skolithos) units, trough cross-bedded, locally showing possible tidal bundles with few whole Scutella (echinoid) shells reworked on foresets, or occasional large-scale (approximately 2 m) planar cross-bedded, bar-accretion units; and (b) slightly finer, darker-coloured reddish-brown sandstone units, heavily bioturbated ( Cruziana-Skolithos) ichnofauna) representing slightly more sheltered settings. Large oysters are present in near-living position in a few thin layers and, more commonly, as reworked, comminuted fragments in sandy layers. Many calcareous pebbles and oyster fragments are bored. Other fossils consist of echinoids ( Scutella), some balanids and reworked foraminifera and bryozoa. The Manciano sands were deposited primarily in a wave-dominated shoreface, containing migrating bars/ridges and affected by wave-induced, possibly tidal-enhanced currents. This tidal influence confirms the opening of the Miocene Apenninic Sea to oceans, both the developing Atlantic Ocean to the west and, through a long, narrow seaway, the Asian portion of the Tethys Sea to the east.

  11. Architectural analysis of a Triassic fluvial system: The Sherwood Sandstone of the East Midlands Shelf, UK

    NASA Astrophysics Data System (ADS)

    Wakefield, Oliver J. W.; Hough, Edward; Peatfield, Alex W.

    2015-08-01

    The Sherwood Sandstone Group of the northeast UK (East Midlands Shelf) has hitherto never been studied in detail to ascertain its palaeoenvironment of deposition, largely because it is poorly exposed. As such, this paper aims to provide the first modern sedimentological interpretation of the Sherwood Sandstone in the east of England based on a field outcrop at the disused quarry at Styrrup. This is in stark contrast to the western parts of England where the Sherwood Sandstone is well exposed and offshore in the North Sea Basin where it is represented by a substantial library of core material where it is also relatively well understood. The outcrop at Styrrup Quarry allows contrasts to be made with the style and expression of the Sherwood Sandstone between eastern and western England. Specifically, this highlights differences around the variation in fluvial discharge (between lowstand and highstand) and the absence of aeolian facies types. It is interpreted that these differences relate to discharge variations between ephemeral and perennial systems with a perennial model proposed for Styrrup Quarry. This model draws upon inferences of additional water input from more local areas, likely topographic uplands of the London-Brabant and Pennine Highs which supplement the primary source of the Variscan Mountains in France with additional water and sediment.

  12. Sedimentary facies analysis and depositional model of the Palaeogene West Crocker submarine fan system, NW Borneo

    NASA Astrophysics Data System (ADS)

    Zakaria, Abdullah Adli; Johnson, Howard D.; Jackson, Christopher A.-L.; Tongkul, Felix

    2013-10-01

    This study outlines a sedimentological analysis of the Palaeogene West Crocker Formation (WCF) around the Kota Kinabalu area of SW Sabah, which represents a large submarine fan depositional system within part of what was the complex and tectonically active margin of NW Borneo. The newly acquired and often extensive outcrop data summarised in this study has resulted in a more complete synthesis of the Crocker fan depositional system than has been previously possible. Seven facies (F1-F7) have been identified which constitute three main facies groups: (1) sand-dominated facies (F1-F3), comprise high- to low-density turbidites and form the dominant part of the WCF, (2) debris flow-dominated facies (F4-F6) comprises mud- and sand-dominant debris flows and mass transport deposits (MTD), which form a secondary but highly distinctive part of the WCF, and (3) mudstone-dominated facies (F7), represent a subordinate part of the WCF. Analysis of the vertical facies successions (from proximal to distal), has resulted in recognition of five major genetic units: (1) channel-levee complex; characterised by thick (30-60 m) thinning and fining upward facies succession, which are dominated in their lower part by thick-bedded (1-6 m), amalgamated high-density (Lowe-type) turbidites with rare debrite beds; the upper part is dominated low-density (Bouma-type) turbidites, without associated debrite beds. (2) Channelised lobes; characterised by 2-10 m thick, coarsening upward, which are overlain by 5-20 m thick fining upward facies successions; these successions are dominated by high-density turbidites (c. 0.5-1 m thick) and linked co-genetic turbidite-debrite beds (0.1-0.5 m thick), with subordinate mudstone facies. (3) Non-channelised lobes; comprise 5-20 m thick coarsening upward facies successions; these start with mudstone facies, which pass gradually upwards into linked co-genetic turbidite-debrite beds; sandstone bed thickness increases upwards, while the debrite caps tend to

  13. Depositional environments of Schuler Formation (Cotton Valley Sands), Upshur County, Texas

    SciTech Connect

    Kast, J.A.

    1983-03-01

    Exploration for tight gas (FERC Section 107) production from the Schuler Formation (Cotton Valley sands) has provided recent data for the recognition of the lower Schuler (Shongaloo member) shoreface facies and delineation of the upper Schuler (Dorcheat member) delta plain complex in Upshur County. Shoreface facies within the lower Schuler have a typical funnel-shaped log pattern (coarsening-upward clastic). In core, the corresponding coarsening-upward sequence grades from offshore to upper shoreface facies. Upper offshore sediments are dominated by a heavily bioturbated and intercalated sandstone/shale sequence with numerous trace fossils, escape traces, and shell debris. Associated facies overlying the upper shoreface are lagoonal. Subaerially exposed mottled red and green siltsone and red mudstone show evidence of root penetration and are interpreted as coastal plain to tidal flat. The marsh deposits (green siltstones and red mudstones) gradationally interbed with a subtidal lagoonal facies containing dark gray, fossiliferous, argillaceous, limestone containing oysters, echinoid fragments, and annelid worm tubes. In an effort to tie the limited core data (4 wells) to a countywide environmental interpretation, sand percent interval slice maps were constructed above and below the ubiquitous subtidal lagoonal marker. These maps and core data in the lower Schuler delineate a strike-oriented, linear clastic shoreline (ENEWSW). Within Upshur County, lower Schuler sediments were deposited as interdeltaic, shoreface facies. The upper member is characterized by a dip-oriented sandstone trend interpreted as an aggradational delta plain complex associated with the Lone Oak delta system.

  14. A Facies Model for Temperate Continental Glaciers.

    ERIC Educational Resources Information Center

    Ashley, Gail Mowry

    1987-01-01

    Discusses the presence and dynamics of continental glaciers in the domination of the physical processes of erosion and deposition in the mid-latitudes during the Pleistocene period. Describes the use of a sedimentary facies model as a guide to recognizing ancient temperate continental glacial deposits. (TW)

  15. Mississippian facies relationships, eastern Anadarko basin, Oklahoma

    SciTech Connect

    Peace, H.W. ); Forgotson, J.M. )

    1991-08-01

    Mississippian strata in the eastern Anadarko basin record a gradual deepening of the basin. Late and post-Mississippian tectonism (Wichita and Arbuckle orogenies) fragmented the single large basin into the series of paired basins and uplifts recognized in the southern half of Oklahoma today. Lower Mississippian isopach and facies trends (Sycamore and Caney Formations) indicate that basinal strike in the study area (southeastern Anadarko basin) was predominantly east-west. Depositional environment interpretations made for Lower Mississippian strata suggest that the basin was partially sediment starved and exhibited a low shelf-to-basin gradient. Upper Mississippian isopach and facies trends suggest that basinal strike within the study area shifted from dominantly east-west to dominantly northwest-southeast due to Late Mississippian and Early Pennsylvanian uplift along the Nemaha ridge. Within the study area, the Chester Formation, composed of gray to dove-gray shales with interbedded limestones deposited on a carbonate shelf, thins depositionally into the basin and is thinnest at its facies boundary with the Springer Group and the upper portion of the Caney Formation. As basin subsidence rates accelerated, the southern edge of the Chester carbonate shelf was progressively drowned, causing a backstepping of the Chester Formation calcareous shale and carbonate facies. Springer Group sands and black shales transgressed northward over the drowned Chester Formation shelf.

  16. A Facies Model for Temperate Continental Glaciers.

    ERIC Educational Resources Information Center

    Ashley, Gail Mowry

    1987-01-01

    Discusses the presence and dynamics of continental glaciers in the domination of the physical processes of erosion and deposition in the mid-latitudes during the Pleistocene period. Describes the use of a sedimentary facies model as a guide to recognizing ancient temperate continental glacial deposits. (TW)

  17. Williams 'elfin facies' Syndrome: A Case Study.

    ERIC Educational Resources Information Center

    Swartz, Stanley L.

    A review of the research literature related to Williams 'elfin facies' Syndrome (a condition including mental retardation and cardiac anomalies), a case study, and the results of an early intervention program, are reported. The medical aspects of the syndrome have been reported with sufficient consistency for a profile to emerge. Psychological…

  18. Control of facies, burial history, and oil migration on diagenesis and reservoir quality: Maracaribo basin, Venezuela

    SciTech Connect

    Ghosh, S.K.; Di Croce, J.; Isea, A.; Gonzalez, C. )

    1990-05-01

    This regional study of the Eocene Misoa Formation is the first attempt to decipher the role of depositional facies, burial history, and timing of oil migration on diagenetic make-up and reservoir quality in the Maracaibo basin. Subsurface data including cores from 11 wells along a northwest-southeast transect in the Urdaneta, Lagunillas, and Barua-Motatan fields reveal that the depositional facies of the three sandstones range from mainly fluvial (Urdaneta) to deltaic-coastal marine in Lagunillas, and typically sublittoral in the Barua-Motatan area. Both authigenic mineralogy and vitrinite reflectance data suggest progressively greater subsidence from the northwest to southeast. Thus, diagenetic grade is immature on the northwest in Urdaneta and mature to supermature in Barua-Moutan where greater mineralogical diversity and porosity/permeability reduction were noted. Similarly, compaction effects are minimum in Urdaneta, and maximum in Barua-Motatan where porosity is highly reduced, and is totally secondary in nature. Other factors, such as grain size, presence of early pore-lining chlorite (in marine facies), infiltrated grain-coating clays (in fluvial facies), and proximity of reservoirs to the post-Eocene unconformity surface also helped preserve or enhance porosity. Timing of oil migration also contributed to variable regional distribution of porosity and permeability. An early migration in the Urdaneta area helped retain much of the original porosity. In contrast, relatively late migration during upper Miocene, especially in the Barua-Motatan area on the southeast, permitted unimpeded silicification and pressure solution, and consequent destruction of all primary porosity.

  19. Tuffaceous sandstones at Site C0011B, Nankai Trough: Sources and emplacement processes

    NASA Astrophysics Data System (ADS)

    Kutterolf, S.; Scudder, R. P.; Freundt, A.; Labanieh, S.; Naruse, H.; Pickering, K. T.; Underwood, M.; Wu, H.; Saito, S.; Kubo, Y.; Iodp Expedition 322 Scientists

    2010-12-01

    During IODP Expedition 322 at the Nankai Trough, sediments down to the lower Miocene have been drilled, which allows us to constrain the physical, compositional and structural characteristics of the subduction input into the seismogenic zone. One major new discovery was an interval of tuffaceous and volcaniclastic sandstones, which we defined as the middle Shikoku Basin facies. Core, LWD logging and seismic data indicate a channel-fill geometry of the sand body, and transport and deposition probably occurred in the distal part of a submarine fan. This lithologic Unit II is late Miocene (>7.07 to ~9.0 Ma) in age and can be divided into two subunits by the abundance of volcanic glass shards, mineral and/or lithic contents, and bulk-rock XRF data. Subunit IIA consists of moderately lithified bioturbated silty claystone with interbeds of tuffaceous sandstone containing 25 to 75 vol% volcanic glass. Major and trace element glass compositions show that the tuffaceous sandstones all came from a similar source region, probably located along the northeast margin of the Shikoku Basin. Relatively low K concentrations indicate source areas at the Izu-Bonin rear arc (Low K facies of Straub 2003). Chemical variations within the single sandstone packages can be attributed to 1) alteration effects (depletion of Mg, Si, Ca, Fe, Ti, and total oxides and increase of Al and K), and 2) a continuous chemical variation in the glass shard compositions of single depositional units, which reflects the tapping of a source of compositionally zoned tephras. The fact that glass shards in each sandstone either have homogeneous composition or define a well-constrained compositional variation trend argues for spatially restricted source areas as opposed to gravity currents resulting, for example, from collapse of large slope sections. The assemblage of lithic components (unimodal volcanic lithic fragments), the vesicularity (amount and vesicle texture) of pumices, and the deposit structure

  20. Evaluation of stratigraphic relations of sandstone-producing reservoirs in upper Council Grove and Chase groups (Permian) in north-central Oklahoma

    SciTech Connect

    Chaplin, J.R. )

    1989-08-01

    Poor well control and the absence of surface stratigraphic control made previous interpretations of the stratigraphic relations of sandstone-producing reservoirs tenuous. Recent extensive analyses of surface outcrops and well and core data support the contention that the major sandstone-producing reservoirs can be physically correlated with formations in the outcrop section. Sandstone bodies within the upper Council Grove Group include Neva sand and Blackwell sand (Neva Limestone), Hotson-Kisner sand (Eskridge Shale), and the Whitney-Hodges sand. The Whitney-Hodges sand correlates, in part, with the Speiser Shale (Garrison Formation) of the outcrop section. However, previous usage suggested tentative correlations with sandstone bodies stratigraphically lower in the section. These sands were probably deposited in channels that were, in part, fluvial, tidal, or estuarine. Production from the Chase Group occurs locally within channelform sandstone bodies referred to as the Hoy-Matfield sand. These sands appear to be equivalent, occupying essentially the position of the Kinney Limestone Member (Matfield Shale) of the outcrop section. Detailed core-hole data at and in the vicinity of Kaw Dam, southeastern Kay County, and outcrops along the shoreline of Kaw Lake at Kaw City, Kay County, clearly demonstrate the facies distribution of the Hoy sand. Core-hole data has also delineated additional potential sandstone reservoirs within and near or at the top of the Fort Riley Limestone Member (Barneston Limestone). The Wolfe sand, a producing sandstone locally, occupies a stratigraphic position within the Doyle Shale.

  1. Measuring and predicting reservoir heterogeneity in complex deposystems: The fluvial-deltaic Big Injun sandstone in West Virginia

    SciTech Connect

    Patchen, D.G.; Hohn, M.E.; Aminian, K.; Donaldson, A.; Shumaker, R.; Wilson, T.

    1993-04-01

    The purpose of this research is to develop techniques to measure and predict heterogeneities in oil reservoirs that are the products of complex deposystems. The unit chosen for study is the Lower Mississippian Big Injun sandstone, a prolific oil producer (nearly 60 fields) in West Virginia. This research effort has been designed and is being implemented as an integrated effort involving stratigraphy, structural geology, petrology, seismic study, petroleum engineering, modeling and geostatistics. Sandstone bodies are being mapped within their regional depositional systems, and then sandstone bodies are being classified in a scheme of relative heterogeneity to determine heterogeneity across depositional systems. Facies changes are being mapped within given reservoirs, and the environments of deposition responsible for each facies are being interpreted to predict the inherent relative heterogeneity of each facies. Structural variations will be correlated both with production, where the availability of production data will permit, and with variations in geologic and engineering parameters that affect production. A reliable seismic model of the Big Injun reservoirs in Granny Creek field is being developed to help interpret physical heterogeneity in that field. Pore types are being described and related to permeability, fluid flow and diagenesis, and petrographic data are being integrated with facies and depositional environments to develop a technique to use diagenesis as a predictive tool in future reservoir development. Another objective in the Big Injun study is to determine the effect of heterogeneity on fluid flow and efficient hydrocarbon recovery in order to improve reservoir management. Graphical methods will be applied to Big Injun production data and new geostatistical methods will be developed to detect regional trends in heterogeneity.

  2. Diagenetic Patterns of the Cretaceous Baseline Sandstone, Southern Nevada: Implications for Controls on Iron-Oxide Cementation and Coloration

    NASA Astrophysics Data System (ADS)

    Duncan, C. J.; Chan, M. A.

    2015-12-01

    The Cretaceous Baseline Sandstone of the Sevier foreland basin deposits in southern Nevada exhibits intense diagenetic iron-oxide coloration and bleaching, and contains abundant cemented masses. The Baseline Formation is ~1 km thick with three alluvial to fluvial members: the basal White (Kbw) Member, overlain by coeval Red (Kbr) and Overton Conglomerate (Kbo) Members. Iron-oxide diagenetic features occur in two broad classes: 1) bedding parallel coloration facies of diffuse to banded red, pink, purple, white, to yellow colors; and 2) concretionary facies of heavily cemented horizons, pods/lenses, spherical to spheroidal concretions, boxworks, pipes, and irregular concretion forms. A distinctive geometry is the occurrence of large (~1 m diameter) spherical "beach ball" concretions within the Kbr. Preliminary mapping of diagenetic features shows that concretionary facies are more common within a ~125 m interval near the bottom of Kbw, and within the lower ~125 m of Kbr. Intense coloration changes are present throughout Kbw but occur only in the lowermost ~150 m of Kbr. In the Kbw, concretionary forms commonly occur in stratigraphic intervals of fine-grained sandstone, siltstone, and mudstone lithologies, whereas cemented masses are much less common in stratigraphic intervals composed of medium-grained sandstone and conglomerate lithologies. Additionally, both Kbw and Kbr Members exhibit rare examples of wood fragments in the center of iron-oxide concretions, suggesting the importance of organics as nucleation sites for precipitation. The distribution of complex and overprinted diagenetic patterns indicates nested scales of processes involving iron-oxide dissolution, mobilization, and precipitation. Overall stratigraphic architecture influenced formation-scale patterns, but specific lithologies and textures influenced the type and distribution of diagenetic facies at outcrop scales, and organic content encouraged cementation at grain-scales.

  3. Paleolatitudinal changes in vertical facies transitions recording late Paleozoic glaciations: a case study from eastern Australia

    NASA Astrophysics Data System (ADS)

    Fielding, C. R.; Frank, T. D.; Shultis, A. I.

    2011-12-01

    Stratigraphic records of the complex and multi-phase late Paleozoic Ice Age (LPIA) have been examined over a 2000 km paleo-polar to paleo-mid latitude transect from Tasmania to Queensland, eastern Australia. In this presentation, we summarize changes in facies assemblages within glacial and nonglacial epochs and the transitions between them, within the coastal to shallow marine Permian succession. In the earliest Permian P1 glacial interval, facies represent proximal proglacial to locally glacial environments in Tasmania (TAS), and an array of mainly marine proglacial to glacimarine environments in New South Wales (NSW) and Queensland (QLD). A trend of more ice-proximal to less ice-proximal facies assemblages is evident from south to north. The end of P1 is represented both by abrupt flooding trends in some areas and by thicker intervals of more gradually fining-upward facies recording progressive deepening elsewhere. The onset of the Sakmarian/Artinskian P2 glacial interval is best-exposed in southern NSW, where an abrupt change to marine proglacial facies is accompanied by evidence for deepening, suggesting isostatic loading of the sedimentary surface. P2 glacial facies are more proximal in NSW than in QLD. Both P1 and P2 intervals preserve complex internal stratigraphy, in many cases recording multiple glacial-interglacial cycles. The close of P2 is again recorded in a variety of ways, with many sections showing a gradual fining-upward and decrease in indicators of glacial conditions. The Kungurian to Capitanian P3 and P4 glacial intervals are in general represented by less proximal facies than their predecessors, typically intervals of outsize clast-bearing mudrocks and sandstones. These in many areas show diffuse boundaries with the nonglacial facies that enclose them. Furthermore, no significant paleolatitudinal changes in the P3 and P4 facies assemblages are evident from TAS to QLD. The documented patterns support the view that the P1 glacial represents the

  4. Primary and redeposited facies from a large-magnitude, rhyolitic, phreatomagmatic eruption: Cana Creek Tuff, Late Carboniferous, Australia

    NASA Astrophysics Data System (ADS)

    McPhie, J.

    1986-07-01

    The Cana Creek Tuff is one of four rhyolitic ignimbrite members of the Late Carboniferous Currabubula Formation, a volcanogenic conglomeratic braidplain sequence exposed along the western margin of the New England Orogen in northeastern New South Wales. The source is not exposed but was probably located tens of kilometres to the west of existing outcrops. The medial to distal parts of the tuff average about 70 m in thickness, are widespread (minimum present area ˜ 1400 km 2), and comprise a primary pyroclastic facies (ignimbrite, ash-fall tuff) and a redeposited volcaniclastic facies (sandstone, conglomerate). Both facies are composed of differing proportions of crystal fragments (quartz, plagioclase, K-feldspar), pumiceous clasts (pumice, shards, fine ash), and accidental lithics. The eruption responsible for this unit was explosive and of large magnitude (dense rock equivalent volume about 100 km 3). That it was also phreatomagmatic in character is proposed on the basis of: the intimate association of primary and redeposited facies; the presence of accretionary lapilli both in ignimbrite and in ash-fall tuff; the fine grain size of juvenile pyroclasts; the low grade of the ignimbrite; and the close similarity in facies, composition and magnitude to the deposits from the 20,000y. B.P. phreatomagmatic eruption at Taupo, New Zealand (the Wairakei and parts of the Hinuera Formations). The eruption began and ended from a vent with excess water available, possibly submersed in a caldera lake, and generated volcaniclastic sheet floods and debris flows. The emplacement of the primary pyroclastic facies is correlated with an intervening stage when the water:magma mass ratio was lower. The deposits from a large-magnitude, phreatomagmatic eruption are predicted to show systematic lateral variations in facies. Primary pyroclastic facies predominate near the source although the preserved stratigraphy is an incomplete record because of widespread contemporaneous erosion

  5. SEQUENCE STRATIGRAPHIC ANALYSIS AND FACIES ARCHITECTURE OF THE CRETACEOUS MANCOS SHALE ON AND NEAR THE JICARILLA APACHE INDIAN RESERVATION, NEW MEXICO-THEIR RELATION TO SITES OF OIL ACCUMULATION

    SciTech Connect

    Jennie Ridgley

    2000-03-31

    Oil distribution in the lower part of the Mancos Shale seems to be mainly controlled by fractures and by sandier facies that are dolomite-cemented. Structure in the area of the Jicarilla Apache Indian Reservation consists of the broad northwest- to southeast-trending Chaco slope, the deep central basin, and the monocline that forms the eastern boundary of the San Juan Basin. Superimposed on the regional structure are broad low-amplitude folds. Fractures seem best developed in the areas of these folds. Using sequence stratigraphic principals, the lower part of the Mancos Shale has been subdivided into four main regressive and transgressive components. These include facies that are the basinal time equivalents to the Gallup Sandstone, an overlying interbedded sandstone and shale sequence time equivalent to the transgressive Mulatto Tongue of the Mancos Shale, the El Vado Sandstone Member which is time equivalent to part of the Dalton Sandstone, and an unnamed interbedded sandstone and shale succession time equivalent to the regressive Dalton Sandstone and transgressive Hosta Tongue of the Mesaverde Group. Facies time equivalent to the Gallup Sandstone underlie an unconformity of regional extent. These facies are gradually truncated from south to north across the Reservation. The best potential for additional oil resources in these facies is in the southern part of the Reservation where the top sandier part of these facies is preserved. The overlying unnamed wedge of transgressive rocks produces some oil but is underexplored, except for sandstones equivalent to the Tocito Sandstone. This wedge of rocks is divided into from two to five units. The highest sand content in this wedge occurs where each of the four subdivisions above the Tocito terminates to the south and is overstepped by the next youngest unit. These terminal areas should offer the best targets for future oil exploration. The El Vado Sandstone Member overlies the transgressive wedge. It produces most of

  6. Sedimentology, petrology, and gas potential of the Brallier Formation: upper Devonian turbidite facies of the Central and Southern Appalachians

    SciTech Connect

    Lundegard, P.D.; Samuels, N.D.; Pryor, W.A.

    1980-03-01

    The Upper Devonian Brallier Formation of the central and southern Appalachian basin is a regressive sequence of siltstone turbidites interbedded with mudstones, claystones, and shales. It reaches 1000 meters in thickness and overlies basinal mudrocks and underlies deltaic sandstones and mudrocks. Facies and paleocurrent analyses indicate differences between the depositional system of the Brallier Formation and those of modern submarine fans and ancient Alpine flysch-type sequences. The Brallier system is of finer grain size and lower flow intensity. In addition, the stratigraphic transition from turbidites to deltaic sediments is gradual and differs in its facies succession from the deposits of the proximal parts of modern submarine fans. Such features as massive and pebbly sandstones, conglomerates, debris flows, and massive slump structures are absent from this transition. Paleocurrents are uniformly to the west at right angles to basin isopach, which is atypical of ancient turbidite systems. This suggests that turbidity currents had multiple point sources. The petrography and paleocurrents of the Brallier Formation indicate an eastern source of sedimentary and low-grade metasedimentary rocks with modern relief and rainfall. The depositional system of the Brallier Formation is interpreted as a series of small ephemeral turbidite lobes of low flow intensity which coalesced in time to produce a laterally extensive wedge. The lobes were fed by deltas rather than submarine canyons or upper fan channel systems. This study shows that the present-day turbidite facies model, based mainly on modern submarine fans and ancient Alpine flysch-type sequences, does not adequately describe prodeltaic turbidite systems such as the Brallier Formation. Thickly bedded siltstone bundles are common features of the Brallier Formation and are probably its best gas reservoir facies, especially when fracture porosity is well developed.

  7. First occurrence of the Salvador Formation in the Jatobá Basin (Pernambuco, Northeast Brazil): Facies characterization and depositional systems

    NASA Astrophysics Data System (ADS)

    Horn, Bruno Ludovico Dihl; Melo Ferrer de Morais, Débora

    2016-12-01

    Fan deltas, constituting proximal depositional systems adjacent to boundary faults, are common features associated with rift basins. The Cretaceous fan delta systems of the Salvador Formation, deposited during the rift phase of the Recôncavo-Tucano-Jatobá Basin, were first reported in the Recôncavo Basin and later discovered in the Tucano Basin. Because of the absence of any outcrops in the Jatobá Basin until now, these alluvial fans were interpreted solely through seismic analysis. We report the first revealed outcrops of the Salvador Formation in that basin and characterize their depositional systems as interlayered with the lacustrine Candeias Formation. Based on facies and architecture, the alluvial system can be subdivided into three associations: (1) proximal fan delta, characterized by meter-scale conglomerate bodies with a predominance of boulders and cobbles with thin sandstone layers; (2) distal fan delta, characterized by sheet-like pebble conglomerate and sandstone layers with flame and load structures; and (3) lacustrine, further subdivided into shallow lake facies reddish shales and mudstones with oolitic limestones and deep lake facies grey to green shales with pyrite. Paleocurrent measurements for the proximal fan association show paleoflow direction varying from SW to SE, which is expected for the rift phase alluvial system. The Recôncavo-Tucano-Jatobá rift system has two conglomeratic units, namely the Salvador and Marizal Formations, the former a syn-rift and the latter a post-rift unit. The absence of sedimentary clasts in the conglomerates, very low maturity, the presence of giant clasts, and a visible relationship between boundary faults in the outcrop, define the syn-rift Salvador Formation characteristics. Based on the facies and paleocurrent analyses, the Salvador Formation deposits in Jatobá Basin were interpreted as a deposition of a debris flow-dominated fan delta, indicating the lacustrine setting represented by the Candeias

  8. Evolution of groundwater chemistry along fault structures in sandstone

    NASA Astrophysics Data System (ADS)

    Dausse, A.; Guiheneuf, N.; Pierce, A. A.; Cherry, J. A.; Parker, B. L.

    2016-12-01

    Fluid-rock interaction across geological structures plays a major role on evolution of groundwater chemistry and physical properties of reservoirs. In particular, groundwater chemistry evolve on different facies according to residence times which can be linked to hydraulic properties of the geological unit. In this study, we analyze groundwater samples collected at an 11 km² site located in southern California (USA) to evaluate the evolution of groundwater chemistry according to different geological structures. Major and minor elements were sampled at the same period of time from 40 wells located along the main structures in the northeast of the site, where major NE-SW trending faults and other oriented ESE-WNW are present in sandstone Chatsworth formation. By analyzing the spatial distribution of ions concentration at the site scale, several hydrochemical compartments (main- and sub-compartments) can be distinguished and are in agreement with structural and hydrological information. In particular, as previously observed from piezometric informations, the shear zone fault serves as a barrier for groundwater flow and separates the site on two mains compartments. In addition, the analysis along major faults oriented orthogonal to this shear zone (ESE-WNW) in the eastern part of the site, shows an increase in mineralization following the hydraulic gradient. This salinization has been confirmed by ionic ratio and Gibbs plots and is attributed to fluid-rock interaction processes. In particular, groundwater chemistry seems to evolve from bicarbonate to sodium facies. Moreover, the gradient of concentrations vary depending on fault locations and can be related to their hydraulic properties and hence to different characteristic times from point to point. To conclude, major faults across the site display different degrees of groundwater chemistry evolution, linked to their physical properties, which may in turn have a large impact on contaminant transport and attenuation.

  9. DRAFT LANDSAT DATA MOSAIC: MONTGOMERY COUNTY, TEXAS; HARRIS COUNTY, TEXAS; FORT BEND COUNTY, TEXAS; BRAZORIA COUNTY, TEXAS; GALVESTON COUNTY, TEXAS

    EPA Science Inventory

    This is a draft Landsat Data Mosaic, which contains remote sensing information for Montgomery County, Texas Harris County, Texas Fort Bend County, Texas Brazoria County, Texas Galveston County, and Texas Imagery dates on the following dates: October 6, 1999 and September 29, 200...

  10. DRAFT LANDSAT DATA MOSAIC: MONTGOMERY COUNTY, TEXAS; HARRIS COUNTY, TEXAS; FORT BEND COUNTY, TEXAS; BRAZORIA COUNTY, TEXAS; GALVESTON COUNTY, TEXAS

    EPA Science Inventory

    This is a draft Landsat Data Mosaic, which contains remote sensing information for Montgomery County, Texas Harris County, Texas Fort Bend County, Texas Brazoria County, Texas Galveston County, and Texas Imagery dates on the following dates: October 6, 1999 and September 29, 200...

  11. Texas Heart Institute

    MedlinePlus

    ... Texas Heart Institute, The University of Texas Health Science Center at Houston, MD Anderson Cancer Center, and The University of Houston. Held most ... for Physicians Fellowships & Residencies School ...

  12. Micro-facies of Dead Sea sediments

    NASA Astrophysics Data System (ADS)

    Neugebauer, Ina; Schwab, Markus J.; Brauer, Achim; Frank, Ute; Dulski, Peter; Kitagawa, Hiroyuki; Enzel, Yehouda; Waldmann, Nicolas; Ariztegui, Daniel; Drilling Party, Dsddp

    2013-04-01

    Lacustrine sediments infilling the Dead Sea basin (DSB) provide a rare opportunity to trace changing climates in the eastern Mediterranean-Levant region throughout the Pleistocene and Holocene. In this context, high-resolution investigation of changes in sediment micro- facies allow deciphering short-term climatic fluctuations and changing environmental conditions in the Levant. The Dead Sea is a terminal lake with one of the largest drainage areas in the Levant, located in the Mediterranean climate zone and influenced also by the Saharo-Arabian deserts. Due to drastic climatic changes in this region, an exceptionally large variety of lacustrine sediments has been deposited in the DSB. These sediments, partially the results of changing lake levels, primarily represent changes in precipitation (e.g. Enzel et al., 2008). Evaporites (halite and gypsum) reflect dry climatic conditions during interglacials, while alternated aragonite-detritus (AAD) is deposited during glacial lake level high-stands. Here we present the first micro-facies inventory of a ~450 m long sediment profile from the deepest part of the northern DSB (ICDP site 5017-1, ~300 m water depth). The sediment record comprises the last two glacial-interglacial cycles, with mainly AAD facies in the upper part of the Amora Formation (penultimate glacial) and the last glacial Lisan Formation. The last interglacial Samra and the Holocene Zeelim Formations are predominantly characterized by thick bedded halite deposits, intercalated by partly laminated detrital marl sequences. Representative sections of the different facies types have been analyzed for micro-facies on petrographic thin sections, supported by high-resolution µXRF element scanning, magnetic susceptibility measurements and microscopic fluorescence analysis. Furthermore, Holocene sediments retrieved at the deep basin core site have been compared to their shallow-water counterpart at the western margin of the lake (core DSEn; Migowski et al., 2004

  13. Recent Developments in Facies Models for Siliciclastic Sediments.

    ERIC Educational Resources Information Center

    Miall, Andrew D.

    1982-01-01

    Discusses theory of facies models (attempts to synthesize/generalize information about depositional environments), strengths/weaknesses of facies modelling, recent advances in facies models for siliciclastic sediments (focusing on fluvial, lacustrine, eolian and glacial environments, clastic shorelines and continental shelves, and clastic…

  14. Recent Developments in Facies Models for Siliciclastic Sediments.

    ERIC Educational Resources Information Center

    Miall, Andrew D.

    1982-01-01

    Discusses theory of facies models (attempts to synthesize/generalize information about depositional environments), strengths/weaknesses of facies modelling, recent advances in facies models for siliciclastic sediments (focusing on fluvial, lacustrine, eolian and glacial environments, clastic shorelines and continental shelves, and clastic…

  15. Upper cretaceous to paleocene depositional sequences and sandstone petrography of southwestern Patagonia (Argentina and Chile)

    NASA Astrophysics Data System (ADS)

    Macellari, C. E.; Barrio, C. A.; Manassero, M. J.

    Upper Cretaceous to Paleocene strata exposed along the Andean margin of Patagonia south of 50°S were deposited in a foreland basin and comprise a complex transition from continental to marine facies. Three unconformity-bounded sequences are observed within the sedimentary succession studied. Sequence 1 (upper Campanian) displays a rapid north-to-south transition from upper delta plain mudstones (Cerro Fortaleza Formation) through lower delta plain and subaqueous delta plain sandstones (La Anita Formation) to delta-slope and basinal turbidites (Alta Vista and Tres Pasos Formations). Sequence 2 (Maastrichtian-Paleocene) was initiated with braided river sediments (La Irene Formation), deposited over a Type II unconformity ( sensu Vail et al., 1984). These rocks are overlain by meandering fluvial sandstones and mudstones (Chorrillo Formation) that interfinger to the south with fossiliferous shallow marine sandstones (upper Cerro Cazador Formation). Sequence 3 (Paleocene) is composed of shallow marine conglomerates and crossbedded sandstones (Calafate and Cerro Dorotea Formations). These rocks are separated by an angular unconformity from subjacent units. Sandstone petrographic analysis indicates the presence of two main petrofacies within the rocks studied. A quartz-rich petrofacies, present to the north of the basin during late Campanian to early Maastrichtian time, was derived from continental crustal block and recycled orogen sources that were possibly exposed to the northwest of the basin. The second petrofacies (volcanic-rich petrofacies) was restricted to the south of the basin during the late Campanian to early Maastrichtian, but covered the entire area during the late Maastrichtian and Paleocene. These sediments were derived from a dissected magmatic arc located to the west of the study area. The presence of abundant tuffaceous intercalations, as well as fresh andesitic fragments, indicates contemporaneous volcanism near the Cretaceous/Tertiary boundary. The

  16. Depositional architecture of Springer Old Woman sandstone, central Anadarko basin, Oklahoma

    SciTech Connect

    O'Donnell, M.R.; Haiduk, J.P.

    1987-08-01

    The fluvial meander belt containing the Old Woman sandstone served as a conduit for clastics transported into the Anadarko basin. Mappable for a distance of more than 30 mi (48 km), sand bodies characterizing this system average 0.5 mi (0.8 km) in width and attain maximum thicknesses of 50-70 ft (15-20 m). Channel and point-bar sandstone facies display a fining-upward sequence and sharp basal contact, as inferred from gamma-ray and resistivity logs. Sandstones of the Old Woman fluvial complex overlie the laminated shales and silts of the penecontemporaneous flood-plain environment. These flood-plain deposits are underlain by crinoidal wackestones and packstones deposited in the subtidal regime. Encroachment of the fluvial complex into a marine setting is interpreted from this sequence. Thin flood-plain deposits and lack of shallow marine clastic sediments suggest rapid advancement. Quartzitic and petrologically mature, the Old Woman sandstone is fine grained, with small-scale troughs and laminations, and a few mudstone rip-up clasts. Diagenesis has altered the mineralogic composition mainly by siliceous and carbonate cementation. Porosity is secondary, resulting from dissolution of various metastable constituents. The Old Woman sandstone was established as a hydrocarbon reservoir in the early 1960s, and sporadic development continued for years. The present-day petroleum market has prompted a resurgence in drilling activity owing to the economic viability of this reservoir. Successful wells are concentrated in newly discovered meander-belt bends; however, the elusiveness of this fluvial system challenges today's exploration geologists as it has for the past quarter century.

  17. Genetic stratigraphy and reservoir characterization of the Spiro sandstone, Red Oak Field, Arkoma Basin, southeastern Oklahoma

    SciTech Connect

    Horn, B.W. )

    1996-01-01

    The Lower Atokan Spiro sandstone is a mixed carbonate-silicilastic reservoir that produces hydrocarbons from three discrete stratigraphic intervals at the Red Oak Field. Reservoir-quality sandstones develop in the seaward stepping sub-Spiro sequence (highstand system tract), landward stepping Foster [open quote]channel,[close quotes] and upper Spiro depositional sequences (transgressive and highstand system tract). The sub-Spiro and Foster [open quote]channel[close quote] sequences are separated by regional unconformity interpreted as a sequence boundary. Regressive marine shoreface cycles, genetically related to the sub-Spiro shale, comprise the lowermost producing interval. Fluvial/estuarine valley-fill (Foster channel) sandstones progressively onlap the sequence boundary overlying the regressive shoreface cycles and juxtapose reservoir-quality sandstones of different sequences, creating a complex reservoir architecture. Upper Spiro reservoir sandstones are developed within marine shoreface cycles that are deposited in a landward-stepping succession (highstand systems tract) following the drowning of incised paleovalleys. These aggradational / retrogradational successions downlap onto the valley-fill and sub-Spiro sequences representing the final stages of Spiro deposition prior to the high stand of sea level during Middle Atokan time. Regional stratigraphic correlations demonstrate progressive basinward truncation of the sub-Spiro regressive shoreface cycles by an erosional surface, creating a network of incised paleovalleys across the Pennsylvanian shelf. Based on core, well log, and outcrop interpretations, the magnitude of the facies offset across this sequence boundary indicates that a significant volume of reservoir-quality sediment has been partitioned basinward of the current producing areas.

  18. Origin of middle Silurian Keefer sandstone, east-central Appalachian basin

    SciTech Connect

    Meyer, S.C.; Textoris, D.A.; Dennison, J.M.

    1988-08-01

    The Keefer Sandstone of northeastern West Virginia and western Maryland was deposited in back-barrier, barrier-island, and marine shelf environments along a prograding, storm-dominated, mesotidal coastline of probable low wave energy. Back-barrier sediments were deposited in tidal-flat and lagoonal environments. Barrier-island sediments are dominated by cross-bedded sandstones deposited in deep, laterally migrating tidal inlets. Erosion accompanying the passage of a migrating tidal inlet usually resulted in the removal of underyling shoreface and shelf sands, so that tidal-inlet sandstones commonly lie with a markedly erosive contact on subtidal shales of the underlying Rose Hill Formation. Sand was transported to the shelf from the coastline by downwelling, storm-generated currents. Chamosite ooids formed in gently agitated waters immediately below fair-weather wave base. Outcrops to the east, which preserve back-barrier and barrier-island lithofacies, record a single basinward progradation of the shoreline. However, outcrops farther west, which preserve finer grained sandstone, shale, and limestone shelf lithofacies, document four progradational events in stacked coarsening-upward sequences. Each is typically capped by transgressive sandstones, commonly hematite ooid-bearing, which mark episodes of coastal retreat. Retreat occurred through shoreface and nearshore erosion. Chamosite ooids were transported basinward during coastal retreat and altered to hematite prior to burial. Transgressive shelf sands contain abundant coarse sand eroded from tidal-inlet deposits. Deposition of the Keefer was a response to a decrease in rate of eustatic sea level rise, or a decrease in basin subsidence rate. This was followed by deposition of the transgressive basin facies of the Rochester Shale.

  19. Reservoir sandstone bodies in lower Silurian Clinton sandstone interval, eastern Ohio

    SciTech Connect

    Coogan, A.H.

    1987-09-01

    The stratigraphic relationships of the sandstones, shales, limestones, dolomites, and related beds of the Lower Silurian Clinton sandstone interval in Ohio have been examined using several thousand well logs from Medina County to Coshocton County in eastern Ohio. This north-south band of counties lies semiparallel to the north-northeast-trending depositional edge of the Clinton lower deltaic and coastal plain. Continuous and discontinuous bar sandstones with patterns similar to barrier island deposits are found at the edge of the deltaic plain. The thicker sandstone reservoirs in these deposits have been prolific oil and gas pools. The discontinuous bar sands are more common, however, and where drilling is sparse or where only the cleaner sandstones are mapped, these bar sands appear as isolated, thick, porous sandstone bodies. Examples exist in Holmes and Wayne Counties, Ohio. Elongate, nearly straight, narrow sandstone bodies occur on the lower deltaic plain, and were deposited in channels that were fluvial or partly estuarine. The channel sandstones are less than 1000 ft wide, extend for distances up to 10 mi and can be seen in Coshocton, Summit, and Medina Counties. The reservoirs in these sandstones are prolific oil and gas producers, but they are not easy to locate. At the seaward end of the elongate channel, sandstones are thick, localized sand bodies that fit in the sedimentological picture as river mouth bars. An example from Medina County illustrates this reservoir geometry at the site of excellent oil production from the Clinton interval.

  20. Facies in stratigraphy: from 'terrains' to 'terranes'.

    USGS Publications Warehouse

    Nelson, C.M.

    1985-01-01

    Concepts of lateral variation in sedimentary rocks and fossil assemblages developed in France from the 1760s; the definitive definition of facies was provided in 1838 by the Swiss geologist Amanz Gressly (1814-65) in his detailed field study of the eastern Jura. His maps and cross-sections of variations in Jurassic and Triassic rocks are illustrated. He believed that variations reflected environmental conditions, as in modern seas, and would eventually permit former depths to be reconstructed. Gressly studied at Strasbourg under Voltz and Thurmann: he collaborated with L.Agassiz, E.Desor and C.Vogt. His work influenced German and French geologists and provided a basis for interpretations of the Alps. But the facies concept was not deeply rooted in American geology until around 1884 (H.S.Williams) and in Britain and Russia until around 1900. I.S.Evans

  1. Magnetic hysteresis of limestones: facies control?

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.; Chow, Nancy; Werner, Tomasz

    1993-03-01

    The hysteresis properties of 116 non-red, marine limestones from 92 localities indicate that remanence is carried by magnetite of pseudo-single-domain (PSD) and small multidomain (MD) size. Pelagic limestones have paramagnetic matrices and hysteresis properties compatible with larger PSD or MD grain sizes of magnetite, probably associated with detrital clay minerals introduced by pelagic rain-out. Thus they may be less suitable recorders of stable remanence. Other limestone facies (excepting dolomitized examples) have diamagnetic matrices. They include shallow—subtidal limestones which tend to have smaller PSD sizes of magnetite, as do backreef—lagoonal, undifferentiated-shelf and reef facies. It is believed that the wide geographical and temporal range of samples minimizes effects related to post-compaction groundwater flow (late diagenesis) and that the associations recognized should be tested in future studies.

  2. Facies and cyclicity within the Oligocene-Early Miocene Panjgur Formation, Khojak-Panjgur Submarine Fan Complex, south-west Makran, Pakistan

    NASA Astrophysics Data System (ADS)

    Kassi, Akhtar Muhammad; Khan, Abdul Salam; Kelling, Gilbert; Kasi, Aimal Khan

    2011-06-01

    The Makran Accretionary Belt covers vast areas of the south-western Makran, Pakistan and extends westwards into coastal Iran. In Pakistan this belt is dominated by an overall regressive succession comprising the Siahan/Hoshab shale (a valley-forming claystone/siltstone-dominant facies) and the ridge-forming, sandstone-dominant facies of the Panjgur Formation, a very thick cyclic succession of Oligocene-Early Miocene turbidites. These formations form part of the "Khojak-Panjgur Submarine Fan Complex". The Panjgur Formation comprises nine distinct facies, which are organized into seven facies associations distinguished by their constituent facies, vertical organizations and lateral geometries. Facies associations include: (1) mid-fan channels, (2) overbank/levee, (3) crevasse-splays, (4) inter-channel, (5) outer-fan-lobes, (6) fan-fringe, and (7) trench floor/basin-plain. The formation displays a hierarchy of 1st, 2nd and 3rd order sedimentary cycles. The 1st order cycles range in thickness from 60 m to 450 m and conceptually correspond to "sequences" or "depositional sequences" formed mainly in response to sea-level fluctuations. Their boundaries are characterized by gradual or abrupt replacement of claystone/siltstone facies of the basin-plain by thin- to thick-bedded mid- to outer-fan turbidites, representing a basinward shift of the facies. The 1st order cycles generally start with thick- to very thick-bedded sandstones of channelized mid-fan facies, passing upwards into a middle part consisting of thin- to thick-bedded sandstone and claystone facies of the outer-fan-lobes and capped by claystone/siltstone-dominant facies of the basin-plain association. These three parts of the 1st order cycles correspond to the lowstand systems tracts (LST), transgressive systems tracts (TST) and highstand systems tract (HST) of the full depositional sequence. The 2nd order cycles, which are generally thinning-up and thickening-up cycles, range in thickness from 4 to 65 m, and

  3. Sequence stratigraphy and facies model of an incised valley fill: The Gironde estuary, France

    SciTech Connect

    Allen, G.P. ); Posamentier, H.W. )

    1993-05-01

    The Gironde estuary was formed by the Holocene drowning of a fluvial valley incised during the Wuerm global sea-level fall. A depositional sequence accumulated in the valley during the eustatic lowstand, the Holocene rise, and the post-Holocene highstand. The sequence comprises a diverse assemblage of lithofacies that can be grouped into lowstand, transgressive, and highstand systems tracts. The objective of this paper is to describe the facies and stratal architecture of this incised-valley fill, and to propose a sequence-stratigraphic model for incised-valley fills in this type of mixed tide- and wave-influenced coastal setting. this study is based on a compilation of the abundant core, borehole, and hydrological data published by a number of authors. The valley fills forms regionally elongated belts of channelized sandstones and are the subject of considerable interest because they furnish potentially important new hydrocarbon play concepts.

  4. Fluvioglacial sandstone reservoirs and deposystem analysis in hydrocarbon exploration of Permian Gidgealpa group, southern Cooper basin, south Australia

    SciTech Connect

    Wild, E.K.; Williams, B.P.J.

    1984-04-01

    The sedimentology of the Permian Gidgealpa Group of the southern Cooper basin currently is being evaluated to ascertain the tectono-sedimentologic evolution of the basin and to determine the architecture of the clastic suite in order to generate exploration plays. The Merrimelia Formation of the Gidgealpa Group was examined regionally in 29 cored wells. The formation attains a maximum thickness of 300 m (1000 ft), and representative facies include glaciofluvial outwash, terrestrial and subaqueous diamictites, and glaciolacustrine, wave-affected, and ripple-laminated sandstones, with thick, monotonous mudrock sequences containing clay-dominant rhythmite horizons. The Tirrawarra Sandstone, analyzed in 32 cored wells, comprises four major facies associations throughout its maximum 75 m (250 ft) thickness. These associations indicate a temporal and spatial evolution of a fluvioglacial to predominantly fluvial system. Initial deposition on low slope, outwash fans, where braided processes operated is indicated. This sedimentation style evolved into a low sinuosity, bedload-dominant, sandy braided system, with high width-to-depth ratio channels. Allocyclic control mechanisms are invoke for late Tirrawarra sedimentation as the facies reveal proximal-distal patterns and the fluvial style changes to a mixed-load channel system. The interfacing and evolutionary pattern of the deposystem indicates that additional reserves potential exists for reservoirs developed locally within the Merrimelia Formation.

  5. Application of actualistic models to unravel primary volcanic control on sedimentation (Taveyanne Sandstones, Oligocene Northalpine Foreland Basin)

    NASA Astrophysics Data System (ADS)

    Di Capua, Andrea; Groppelli, Gianluca

    2016-05-01

    This work is focused on the Taveyanne Sandstones (Grés de Taveyanne), an Oligocene volcaniclastic turbidite sequence cropping out in the Northern Alpine Molassa between SE France and Central Switzerland, with the aim to investigate the temporal relationship between volcanic activity and sediment supply. Detailed stratigraphic, sedimentological, and petrographic (XRD analyses on mudstones and point counts on sandstones) studies conducted on three sections (Col de l'Oulette and Flaine in SE France, Taveyanne in SW Switzerland) allow a discrimination of three main facies, among which only one is extremely enriched in volcaniclastic detritus and characterized by features similar to those of disaggregated pyroclastic density current deposits. The other two facies are characterized by variable to no volcanic detritus but supplied by crystalline and sedimentary detritus. Such sediment trends are similar to those of modern, volcanically controlled source-to-sink systems. This allows a reinterpretation of the Taveyanne Sandstones as a syn-volcanic turbidite system, episodically supplied by large amounts of volcanic detritus, which periodically modified the drainage paths. Moreover, the well-known temporal and spatial persistence of such modifications in modern settings leads to conciliate the syn-volcanic supply with the location of the volcanic centers in the internal part of the Alps, without invoking particular climatic and tectonic conditions controlling foreland sedimentation.

  6. Facies, Stratigraphic and Depositional Model of the Sediments in the Abrolhos Archipelago (Bahia, BRAZIL)

    NASA Astrophysics Data System (ADS)

    Matte, R. R.; Zambonato, E. E.

    2012-04-01

    Located in the Mucuri Basin on the continental shelf of southern Bahia state, northeast Brazil, about 70 km from the city of Caravelas,the Abrolhos archipelago is made up of five islands; Santa Barbara, Redonda, Siriba, Guarita and Sueste. The exhumed sediments in the Abrolhos archipelago are a rare record of the turbidite systems which fill the Brazilian Atlantic Basin, and are probably an unprecedented example of a plataform turbidite system (Dr. Mutti, personal communication). Despite the limited area, the outcrops display a wide facies variation produced by different depositional processes, and also allow for the observation of the layer geometries. Associated with such sedimentary rocks, the Abrolhos Volcanic Complex belongs stratigraphically to the Abrolhos Formation. These igneous rocks were dated by the Ar / Ar method, with ages ranging from 60 to 40 My, placing such Volcanic Complex between the Paleocene and Eocene. The sedimentary section is best exposed in the Santa Barbara and Redonda islands and altogether it is 70 m thick. The measured vertical sections show a good stratigraphic correlation between the rocks of the western portion of the first island and those of Redonda Island. However, there is no correlation between the eastern and western portions of Santa Barbara Island, since they are very likely interrupted by the igneous intrusion and possibly by faulting. The sedimentary stack consists of deposits with alternated regressive and transgressive episodes interpreted as high frequency sequences. The coarse facies, sandstones and conglomerates, with abrupt or erosive bases record regressive phases. On the other hand, finer sandstones and siltstones facies, which are partly bioturbated, correspond to phases of a little sediment supply. In the central and eastern portions of Santa Barbara Island, there is a trend of progradational stacking, while both in the western portion of Santa Barbara and in Redonda islands an agradational trend is observed

  7. Application of turbidite facies of the Stevens Oil Zone for reservoir management, Elk Hills Field, California

    SciTech Connect

    Reid, S.A.; Thompson, T.W. ); McJannet, G.S. )

    1996-01-01

    A detailed depositional model for the uppermost sand reservoirs of the Stevens Oil Zone, Elk Hills Field, California, contains three facies: turbidite channel-fill sand bodies, overbank Sandstone and mudstone, and pelagic and hemipelagic siliceous shale. Sand bodies are the primary producing facies and consist of layered, graded sandstone with good permeability. The presence of incipient anticlines with subsea relief in the late Miocene resulted in deposition of lenticular and sinuous sand Was within structurally created channels. Relief of these structural channels was low when the earliest sand bodies were deposited, leading to a wide channel complex bounded by broad overbank deposits of moderate to low permeability. As deposition proceeded, increased structural relief constrained the channels, resulting in narrower sand body width and relatively abrupt channel terminations against very low permeability siliceous shale. With post-Miocene uplift and differential compaction, stratigraphic mounding of sand bodies helped create structural domes such as the 24Z reservoir. Stratigraphic traps including the 26R reservoir were also created. Such traps vary in seal quality from very effective to leaky, depending on the lateral transition from sand bodies to siliceous shale. Application of the Elk Hills turbidity model (1) provides a framework for monitoring production performance in the 24Z and Northwest Stevens waterflood projects; and for tracking gas migration into and out of the 26R reservoir, (2) helps b identify undeveloped locations in the 26R reservoir ideally suited for horizontal wells, (3) has led to the identification of two new production trends in the 29R area, and (4) makes possible the development of exploration plays in western Elk Hills.

  8. Application of turbidite facies of the Stevens Oil Zone for reservoir management, Elk Hills Field, California

    SciTech Connect

    Reid, S.A.; Thompson, T.W.; McJannet, G.S.

    1996-12-31

    A detailed depositional model for the uppermost sand reservoirs of the Stevens Oil Zone, Elk Hills Field, California, contains three facies: turbidite channel-fill sand bodies, overbank Sandstone and mudstone, and pelagic and hemipelagic siliceous shale. Sand bodies are the primary producing facies and consist of layered, graded sandstone with good permeability. The presence of incipient anticlines with subsea relief in the late Miocene resulted in deposition of lenticular and sinuous sand Was within structurally created channels. Relief of these structural channels was low when the earliest sand bodies were deposited, leading to a wide channel complex bounded by broad overbank deposits of moderate to low permeability. As deposition proceeded, increased structural relief constrained the channels, resulting in narrower sand body width and relatively abrupt channel terminations against very low permeability siliceous shale. With post-Miocene uplift and differential compaction, stratigraphic mounding of sand bodies helped create structural domes such as the 24Z reservoir. Stratigraphic traps including the 26R reservoir were also created. Such traps vary in seal quality from very effective to leaky, depending on the lateral transition from sand bodies to siliceous shale. Application of the Elk Hills turbidity model (1) provides a framework for monitoring production performance in the 24Z and Northwest Stevens waterflood projects; and for tracking gas migration into and out of the 26R reservoir, (2) helps b identify undeveloped locations in the 26R reservoir ideally suited for horizontal wells, (3) has led to the identification of two new production trends in the 29R area, and (4) makes possible the development of exploration plays in western Elk Hills.

  9. Experimental Investigation on Dilation Mechanisms of Land-Facies Karamay Oil Sand Reservoirs under Water Injection

    NASA Astrophysics Data System (ADS)

    Lin, Botao; Jin, Yan; Pang, Huiwen; Cerato, Amy B.

    2016-04-01

    The success of steam-assisted gravity drainage (SAGD) is strongly dependent on the formation of a homogeneous and highly permeable zone in the land-facies Karamay oil sand reservoirs. To accomplish this, hydraulic fracturing is applied through controlled water injection to a pair of horizontal wells to create a dilation zone between the dual wells. The mechanical response of the reservoirs during this injection process, however, has remained unclear for the land-facies oil sand that has a loosely packed structure. This research conducted triaxial, permeability and scanning electron microscopy (SEM) tests on the field-collected oil sand samples. The tests evaluated the influences of the field temperature, confining stress and injection pressure on the dilation mechanisms as shear dilation and tensile parting during injection. To account for petrophysical heterogeneity, five reservoir rocks including regular oil sand, mud-rich oil sand, bitumen-rich oil sand, mudstone and sandstone were investigated. It was found that the permeability evolution in the oil sand samples subjected to shear dilation closely followed the porosity and microcrack evolutions in the shear bands. In contrast, the mudstone and sandstone samples developed distinct shear planes, which formed preferred permeation paths. Tensile parting expanded the pore space and increased the permeability of all the samples in various degrees. Based on this analysis, it is concluded that the range of injection propagation in the pay zone determines the overall quality of hydraulic fracturing, while the injection pressure must be carefully controlled. A region in a reservoir has little dilation upon injection if it remains unsaturated. Moreover, a cooling of the injected water can strengthen the dilation potential of a reservoir. Finally, it is suggested that the numerical modeling of water injection in the Karamay oil sand reservoirs must take into account the volumetric plastic strain in hydrostatic loading.

  10. Surface gamma-ray logs as a correlation tool between outcrop and subsurface: Application to the Silurian-Devonian of west Texas and southern New Mexico

    SciTech Connect

    Colleary, W.M. ); Crafton, J.W. Gas Research Institute, Chicago, IL )

    1992-04-01

    Outcrop gamma-ray logs are an excellent tool for correlation between surface measured sections and subsurface well logs. The work presented here illustrates the utility of constructing such profiles and the applicability of this technique to carbonate sequences such as those of the Permian basin. Outcrop sections with gamma-ray profiles have been measured over the Silurian-Devonian section in three separate areas. These sections are located in the Sacramento Mountains of southern New Mexico, and the northern Franklin Mountains and Hueco Mountains of west Texas. A hand-held Scintrex Model BGS-4 Digital Scintillometer was used to measure surface gamma radiation while detailed stratigraphic sections were being measured and described. Data were collected at regularly spaced intervals along the section. The scintillometer detects natural radiation emitted by radioactive elements that occur in most clay minerals and generally are more abundant in shales than in sandstones or carbonates. The lithology of poorly exposed or covered units also may be inferred from surface gamma-ray profiles. Organic-rich black shales are particularly radioactive, as are condensed sections. The strength of this method does not lie in the absolute reading of gamma radiation. The value of this tool lies in recognizing patterns within each profile, directly relating these patterns to their associated facies, and correlating them with subsurface profiles.

  11. Native walnuts of Texas

    USDA-ARS?s Scientific Manuscript database

    Three species of Juglans occur naturally in Texas. Eastern Black walnut, J. nigra is found in eastern to central Texas. J. major, the Arizona walnut, is reported in scattered, disjunct populations from central to west Texas. J. microcarpa, the Little walnut, occurs from central to west Texas. Hy...

  12. Transgressive parasequences in Cretaceous upper Frontier (Wall Creek) sandstone

    SciTech Connect

    Huff, M.C. )

    1989-09-01

    Transgression during the upper Turonian in the area of the present-day Powder River basin was episodic: initial sea level rise, followed by a gradual overtaking of sea level rise by sedimentation rate, then another sea level rise to higher than it was before. Most of the parasequences produced consist of a transgressive lag directly overlain by coarsening-upward progradational deposits. Others are more complex. These more complex parasequences are composed of a transgressive lag overlain by fining-upward transgressive sediments overlain by coarsening-upward regressive deposits. A condensed section or omission surface separating the transgressive portion from the regressive portion is rarely found. Several such packages are found stacked vertically in areas that were near the basin margin. Farther paleolandward, part of the record preserved in the marine parasequences was removed by erosion. In the deeper parts of the basin, the condensed section encompasses part or all of the record. Capping the last progradational deposit in some locations in a shelf sand ridge. Understanding the details of sequence stratigraphy increases the accuracy of its use for predicting where to find reservoir sandstones. Certain Wall Creek facies, such as shelf sand ridges, are important petroleum reservoirs in the Powder River basin.

  13. Location of Mars Sandstone Target Windjana

    NASA Image and Video Library

    2014-04-25

    In this Mars Reconnaissance Orbiter view of the Curiosity rover mission waypoint called the Kimberley, the red dot indicates the location of a sandstone target, Windjana, selected for close-up inspection.

  14. Knobbly Textured Sandstone on Mount Sharp, Mars

    NASA Image and Video Library

    2016-03-11

    Patches of Martian sandstone visible in this view from NASA Curiosity Mars rover have a knobbly texture due to nodules apparently more resistant to erosion than the host rock in which some are still embedded.

  15. Sedimentology and reservoir heterogeneity of a valley-fill deposit-A field guide to the Dakota Sandstone of the San Rafael Swell, Utah

    USGS Publications Warehouse

    Kirschbaum, Mark A.; Schenk, Christopher J.

    2010-01-01

    Valley-fill deposits form a significant class of hydrocarbon reservoirs in many basins of the world. Maximizing recovery of fluids from these reservoirs requires an understanding of the scales of fluid-flow heterogeneity present within the valley-fill system. The Upper Cretaceous Dakota Sandstone in the San Rafael Swell, Utah contains well exposed, relatively accessible outcrops that allow a unique view of the external geometry and internal complexity of a set of rocks interpreted to be deposits of an incised valley fill. These units can be traced on outcrop for tens of miles, and individual sandstone bodies are exposed in three dimensions because of modern erosion in side canyons in a semiarid setting and by exhumation of the overlying, easily erodible Mancos Shale. The Dakota consists of two major units: (1) a lower amalgamated sandstone facies dominated by large-scale cross stratification with several individual sandstone bodies ranging in thickness from 8 to 28 feet, ranging in width from 115 to 150 feet, and having lengths as much as 5,000 feet, and (2) an upper facies composed of numerous mud-encased lenticular sandstones, dominated by ripple-scale lamination, in bedsets ranging in thickness from 5 to 12 feet. The lower facies is interpreted to be fluvial, probably of mainly braided stream origin that exhibits multiple incisions amalgamated into a complex sandstone body. The upper facies has lower energy, probably anastomosed channels encased within alluvial and coastal-plain floodplain sediments. The Dakota valley-fill complex has multiple scales of heterogeneity that could affect fluid flow in similar oil and gas subsurface reservoirs. The largest scale heterogeneity is at the formation level, where the valley-fill complex is sealed within overlying and underlying units. Within the valley-fill complex, there are heterogeneities between individual sandstone bodies, and at the smallest scale, internal heterogeneities within the bodies themselves. These

  16. Cambrian/Early Ordovician sequence stratigraphy and Mt. Simon sandstone petrology - Michigan basin

    SciTech Connect

    Cottingham, J.T.

    1990-05-01

    Rocks of Cambrian and Early Ordovician age are well known in Wisconsin and otber areas surrounding the Michigan basin but because of burial depth ranging from 3,000 to 16,000 ft relatively little is known about these rocks in Michigan. Core and cuttings examination demonstrate that similar stratigraphic sequences exist between the central Michigan basin and surrounding regions. Basinal lithofacies are similar to their outcrop counterparts in Wisconsin and are correlated on the basis of sediment types, sedimentary structures, and the concept of sequence stratigraphy. The Mount Simon Sandstone in Michigan correlates with that observed in Indiana, Illinois, Wisconsin, and Iowa. Isopach data throughout the Midwest indicates a single depocenter in northeastern Illinois, with an arm extending into the central Michigan basin. Sedimentary structures and lithology indicate a subtidal marine environment that may be a transition to a shoreward nonmarine fluvial to eolian environment. Observed diagenetic facies are influenced primarily by depth of burial. The deep facies (below 14,250 ft) exhibits extreme physical and chemical compaction of quartz grains. Quartz cement is predominant with less than 1% porosity present. The shallow facies (above 8,900 ft) exhibits pervasive dolomite and quartz cements and authigenic clays, Secondary porosity developed from dissolution of carbonate, quartz, and K-feldspar.

  17. Intersecting faults and sandstone stratigraphy at the Cerro Prieto geothermal field

    SciTech Connect

    Vonder Haar, S.; Howard, J.H.

    1980-02-01

    The northwest-southeast trending Cerro Prieto fault is part of a major regional lineament that extends into Sonaro and has characteristics of both a wrench fault and an oceanic transform fault. The distribution of lithologies and temperature within the field was studied by comparing data from well cuttings, cores, well logs, and geochemical analyses. Across the earliest developed portion of the field, in particular along a 1.25-km northeast-southwest section from well M-9 to M-10, interesting correlations emerge that indicate a relationship among lithology, microfracturing, and temperature distribution. In the upper portion of Reservoir A of this stratigraphic section, between 1200 and 1400 m, the percentage of sandstones ranges from 20 to 55. Temperatures are 225/sup 0/ to 275/sup 0/C based on well logs, calcite isotope maxima, and Na-K-Ca indices. The study shows that an isothermal high in this vicinity corresponds to the lowest total percentage of sandstones. Scanning electron microphotographs of well cores and cuttings from sandstone and shale units reveal clogging, mineral dissolution, and mineral precipitation along microfractures. The working hypothesis is that these sandy shale and siltstone facies are most amenable to increased microfracturing and, in turn, such microfracturing allows for higher temperature fluid to rise to shallower depths in the reservoir.

  18. Behavior of Sandstones Under Heat Treatment

    NASA Astrophysics Data System (ADS)

    Keppert, M.; Fořt, J.; Trník, A.; Koňáková, D.; Vejmelková, E.; Pokorný, J.; Svora, P.; Pavlík, Z.; Černý, R.

    2017-04-01

    Knowledge of materials behavior under heat treatment is of high importance in construction and safety engineering; tunnels represent a special field because of their specific safety issues. In the case of fire, tunnel structure and surrounding rock are subjected to extreme temperatures which induces irreversible changes in the material's microstructure and consequently its mechanical properties. Significant portion of the Earth's crust is formed by sandstones; this group of sedimentary rocks is highly variable in structure, composition and engineering properties. Quartz grains (alternatively together with other minerals) form the clastic part of sandstones; the space between clasts is filled by variable amount of cement and matrix which can contain particularly clay minerals, quartz and calcite. The porosity of sandstones is again highly variable from a nearly compact material to a highly porous one. The paper aims to find out and explain differences in response of various kinds of sandstones to heat treatment. The behavior of a representative set of sandstones under heat treatment was studied by TG/DSC, thermodilatometry and residual strength measurement. These experiments were accompanied by SEM and porosimetry measurement. The effect of increased temperature on the compressive strength was found to be crucially dependent on the nature of the cement and matrix present in the individual rock. The rocks with calcite cement which had high initial strength and low porosity were damaged by calcite decomposition. The siliceous sandstones were damaged by cracking due to thermally induced volume changes. In contrary, the strength of the clayey sandstones was even improved after the heat treatment. It can be concluded that behavior of sandstone under heat treatment is controlled by its composition and diagenesis.

  19. Sedimentary facies and palynofacies assemblages in an Eocene perennial lake, Lumbrera formation, northwest Argentina

    NASA Astrophysics Data System (ADS)

    del Papa, C.; Quattrocchio, M.

    2002-10-01

    The combined application of sedimentary facies and palynofacies analyses constitutes a valuable method for paleoenvironmental and paleoclimatic reconstructions, especially in continental strata in which fossil information is scarce or absent. In this paper, we present an integrated model based on this methodology for the Eocene lacustrine rocks of the Lumbrera Formation in northwest Argentina. The new data contribute to the understanding of the evolution of the final post-rift stage of the Salta Group in northwest Argentina. The lacustrine deposits of the Lumbrera Formation are named Faja Verde I and Faja Verde II. In the Alemanı´a area, the Faja Verde II consists of green claystones and mudstones interbedded with sandstones and deposited in a perennial lake and fluvio-dominated delta complex. In addition, there are two major cycles that are separated by a flooding surface. The basal cycle is a retrogradational parasequence set, and the upper cycle is a progradational parasequence set. The palynofacies analysis and organic matter analytical data (TOC and Pyrolysis Rock-Eval) of each sedimentary facies are closely related to the dynamics of the depositional environment. Proximal prodelta (Palynofacies association I), distal prodelta (Palynofacies association II), lacustrine (Palynofacies association III), and interdistributary bay fill (Palynofacies association IV) subenvironments are differentiated. Each is characterized by a definitive relationship of phytoclasts, amorphous, palynomorphs, fluorescence index, quality, and quantity of the organic matter. The variation of occurrence of the Pediastrum- Botryococcus algae reflects fluctuations in the level of water related to identified cycles of shallowing.

  20. Neotectonic evolution of the Brazilian northeastern continental margin based on sedimentary facies and ichnology

    NASA Astrophysics Data System (ADS)

    Gandini, Rosana; Rossetti, Dilce de Fátima; Netto, Renata Guimarães; Bezerra, Francisco Hilário Rego; Góes, Ana Maria

    2014-09-01

    Quaternary post-Barreiras sediments are widespread along Brazil's passive margin. These deposits are well exposed in the onshore Paraíba Basin, which is one of the rift basins formed during the Pangean continental breakup. In this area, the post-Barreiras sediments consist of sandstones with abundant soft-sediment deformation structures related to seismicity contemporaneous with deposition. The trace fossils Thalassinoides and Psilonichnus are found up to 38 m above modern sea level in sandstones dated between 60.0 (± 1.4) and 15.1 (± 1.8) ka. The integration of ichnological and sedimentary facies suggests nearshore paleoenvironments. Such deposits could not be related to eustatic sea-level rise, as this time coincides with the last glaciation. Hence, an uplift of 0.63 mm/yr, or 1.97 mm/yr if sea level was 80 m lower in the last glaciation, would have been required to ascend the post-Barreiras sediments several meters above the present-day sea level during the last 60 ka. This would suggest that the post-rift stage of the South American eastern passive margin may have experienced tectonic reactivation more intense than generally recognized. Although more complete data are still needed, the information presented herein may play an important role in studies aiming to decipher the Quaternary evolution of this passive margin.

  1. Diagenetic capping of carbonate reservoir facies

    SciTech Connect

    Lighty, R.G.

    1984-04-01

    The diagenetic model proposed involves the effect of submarine cementation on previously lithified carbonates, such as submerged relict shelf-margin buildups (e.g., drowned reefs, ooid shoals) or previously subaerially exposed formations (e.g., dune ridges) that were submerged by later sea level rise. These deposits generally have pronounced topographic relief (visible on seismic), good reservoir geometries, and high internal porosity of either primary or secondary origin. Petrologic studies on examples of both of these situations, a submerged early Holocene barrier reef off Florida and a 175-km (110-m) long submerged Pleistocene eolian ridge in the Bahamas, show that their exposed surface and uppermost facies (0.1 m, or 0.3 ft, below top) are further infilled and cemented, creating an extensively lithified, low porosity/low permeability zone or diagenetic cap rock. Quantitative mineralogic studies of occluding cements reveal an exponential reduction in porosity while moving upward into the seal zone. Submarine cements effectively infill and form a surficial permeability barrier that acts to impede further diagenesis and porosity reduction within underlying potential reservoir facies. To form this diagenetic seal only requires that the original carbonate buildup be resubmerged for some brief period of time prior to subsequent burial by sediments. If buildup accumulation later resumes without intermediate sediment burial, a common stratigraphic situation, the diagenetic seal would represent a disconformity separating two similar facies. The early formation of a diagenetic cap rock lends support to models of early hydrocarbon migration and emplacement. Prediction and recognition of submarine diagenetic seals will aid in exploration and development of obvious buildup reservoirs as well as subtle intraformational traps.

  2. Microstructure of deformed graywacke sandstones

    SciTech Connect

    Dengler, L.A.

    1980-03-05

    Microsctures in low-permeability graywacke sandstones were studied by optical and scanning electron microscopy (SEM). SEM specimens were prepared by ion-bombardment of thick polished samples. The undeformed rock contains grains in a matrix composed primarily of authigenic chlorite and kaolinite. Chlorite platelets are randomly arranged in face-to-edge relation to one another. Kaolinite occurs as pseudohexagonal crystals stacked face-to-face in pore filling books. Uniaxial-stress experiments covered a range of confining pressures from .1 to 600 MPa. Below 50 MPa confining pressure, intergranular fracturing occurs within the fault zone and near the sample's cylindrical surface. Between 100 and 300 MPa confining pressure, fault zones contain highly fractured grains, gauge and slickensides on grain surfaces. At 600 MPa, the sample contains a diffuse shear zone of highly fractured grains and no well-defined fault. In all samples, the distribution of microcracks is heterogeneous. Different clay minerals exhibit different modes of deformation. Chlorite structure responds to applied stress by compaction, reducing both pore size and volume. Chlorite platelets are plastically deformed in even the least strained samples. Kaolinite does not deform plastically in any of the samples examined. Deformation of kaolinite is restricted to toppling of the book structure. Dilatant crack growth was studied in two samples unloaded prior to failure. Uniaxially-strained samples deform primarily along grain boundaries, producing intergranular cracks and realignment of chlorite platelets. Intragranular crack density is linearly related to axial-strain, although grains are less fractured than in uniaxially-stressed samples tested at equivalent mean pressures. Cracks are rarely longer than a grain diameter. Nuclear-explosively deformed samples were recovered after the Rio Blanco gas stimulation experiment. (JGB)

  3. "Sydney sandstone": Heritage Stone from Australia

    NASA Astrophysics Data System (ADS)

    Cooper, Barry; Kramar, Sabina

    2014-05-01

    Sydney is Australia's oldest city being founded in 1788. The city was fortunate to be established on an extensive and a relatively undeformed layer of lithified quartz sandstone of Triassic age that has proved to be an ideal building stone. The stone has been long identified by geologists as the Hawkesbury Sandstone. On the other hand the term "Sydney sandstone" has also been widely used over a long period, even to the extent of being utilised as the title of published books, so its formal designation as a heritage stone will immediately formalise this term. The oldest international usage is believed to be its use in the construction of the Stone Store at Kerikeri, New Zealand (1832-1836). In the late 19th century, public buildings such as hospitals, court houses as well as the prominent Sydney Town Hall, Sydney General Post Office, Art Gallery of New South Wales, State Library of New South Wales as well as numerous schools, churches, office building buildings, University, hotels, houses, retaining walls were all constructed using Sydney sandstone. Innumerable sculptures utilising the gold-coloured stone also embellished the city ranging from decorative friezes and capitals on building to significant monuments. Also in the late 19th and early 20th century, Sydney sandstone was used for major construction in most other major Australian cities especially Melbourne, Adelaide and Brisbane to the extent that complaints were expressed that suitable local stone materials were being neglected. Quarrying of Sydney sandstone continues today. In 2000 it was recorded noted that there were 33 significant operating Sydney sandstone quarries including aggregate and dimension stone operations. In addition sandstone continues to be sourced today from construction sites across the city area. Today major dimension stone producers (eg Gosford Quarries) sell Sydney sandstone not only into the Sydney market but also on national and international markets as cladding and paving products

  4. Reservoir quality in relation to facies, burial history, and oil migration: A review

    SciTech Connect

    Ghosh, S.K. )

    1993-02-01

    The diagenetic make-up and, in consequence, the ultimate reservoir quality of a sand body depends on depositional facies, as well as on burial history, diagenetic fluid chemistry and timing of oil migration. A regional subsurface study in the Maracaibo Basin, Venezuela along a northwest-southeast transect in the Urdaneta, Lagunillas and Barua-Motatan fields reveal that depositional facies of the reservoir sandstones range from mainly fluvial (Urdaneta) to deltaic-coastal marine in Lagunillas, and typically sublittoral in the Barua-Motatan area. Factors such as granulometry, development of early pore-lining chlorite (in marginal marine facies), infiltrated grain-coating clays (fluvial B-6 sands), and proximity of reservoirs to the post-Eocene unconformity, have preserved, enhanced or otherwise influenced reservoir quality. Data on authigenic mineralogy, vitrinite reflectance and burial history indicate a progressively greater subsidence from northwest to southeast. As a result, diagenetic grade is immature in Urdaneta where porosity/permeability values are the highest. In contrast, the Barua-Motatan field in the southeast is typified by a higher grade of diagenesis, varied authigenic mineralogy, and severe deterioration of reservoir quality. Similarly, degree of compaction progressively increases from northwest to southeast. Timing of oil migration have parallelly contributed to systematic regional variation in reservoir quality. An early migration in Urdaneta has been favorable to preservation of original porosity. In contrast, late migration during Upper Miocene, in the Barua-Motatan field, indirectly permitted abundant silicification and consequent destruction of virtually all primary porosity. Thus both pre- and post-depositional parameters are important constraints which should be considered while evaluating quality of siliciclastic reservoirs.

  5. Controls on synchronous ephemeral- and perennial-river sedimentation in the middle sandstone member of the Triassic Chinle Formation, northeastern New Mexico, U.S.A.

    NASA Astrophysics Data System (ADS)

    Deluca, J. L.; Eriksson, K. A.

    1989-02-01

    The middle sandstone member of the upper Triassic Chinle Formation in northeastern New Mexico consists of ephemeral-river deposits along the Front Range adjacent to the Ancestral Rocky Mountains and perennial braided-river deposits on the Plains to the east. The two fluvial systems were synchronous; the ephemeral rivers existed as transverse tributaries to a perennial trunk system that flowed from south to north. Proximal ephemeral-stream deposits are characterized by 60-80 m thick sequences of coarse-grained, siliciclastic sediments deposited principally by overbank sheetflooding. Facies associations are dominated by sandstone with horizontal stratification and subordinate sets of tabular-tangential and trough cross-stratification. Incised streamflood deposits are represented by channeled conglomerates and single-story, massive and trough cross-stratified sandstones. Distal ephemeral-stream deposits are distinguished by their lenticular geometries, thicknesses of 20-30 m, and sedimentary structures indicative mainly of lower-flow-regime stream flooding. Channeled conglomerates and trough cross-stratified and parallel-stratified sandstones are capped by trough cross-laminated and subordinate horizontally stratified sandstones. Facies associations in the deposits of the trunk system are comparable to those of the Platte and South Saskatchewan braided rivers. Sets and cosets of tabular-tangential or trough cross-stratified conglomerate and sandstone are separated by variable thicknesses of horizontally stratidied sandstone. These facies dominate 10-30 m thick, sheet-like, siliciclastic bodies that are traceable laterally for tens of kilometers and are separated by comparable or lesser thicknesses of red mudstone. Both extrabasinal (allocyclic) and intrabasinal (autocyclic) controls influenced sandstone body geometries in the middle Chinle Formation. Uplift and subsidence determined the position of base level that, in turn, determined the nature of autocyclic

  6. Geologic controls on reservoir properties of low-permeability sandstone, Frontier Formation, Moxa Arch, southwest Wyoming. Topical report, April 1989-April 1992

    SciTech Connect

    Dutton, S.P.; Scott, H.; Laubach, S.E.

    1992-06-01

    The report examines the influence of stratigraphy, diagenesis, natural fractures, and in situ stress on low-permeability, gas-bearing sandstone reservoirs of the Upper Cretaceous Frontier Formation along the Moxa Arch in the Green River Basin, southwestern Wyoming. The main stratigraphic controls on distribution and quality of Frontier reservoirs are sandstone continuity and detrital clay content. The Frontier was deposited in a fluvial-deltaic system, in which most reservoirs lie in marine upper shoreface and fluvial channel-fill sandstone facies. The major causes of porosity loss in Frontier sandstones during burial diagenesis were mechanical and chemical compaction and cementation by calcite, quartz, and authigenic clays. Despite extensive diagenetic modification, reservoir quality is best in facies that had the highest porosity and permeability at the time of deposition. Natural fractures are sparse in Frontier core, but outcrop studies show that fractures commonly are in discrete, irregularly spaced swarms separated by domains having few fractures. Natural fracture swarms are potential high-permeability 'sweet spots.' Stress-direction indicators give highly scattered estimates of maximum horizontal compression direction ranging from north to east or northeast. The scatter may reflect interference of natural fractures with measurements of stress directions, as well as spatially variable stress directions and low horizontal stress anisotropy.

  7. New insights into the provenance of Saudi Arabian Palaeozoic sandstones from heavy mineral analysis and single-grain geochemistry

    NASA Astrophysics Data System (ADS)

    Bassis, Alexander; Hinderer, Matthias; Meinhold, Guido

    2016-03-01

    Saudi Arabian Palaeozoic siliciclastics cover a stratigraphic range from the Cambrian to the Permian. They crop out along the eastern margin of the Arabian Shield and are comprised of highly mature sandstones. Their heavy mineral assemblage reflects their mineralogical maturity and is dominated by the ultra-stable phases zircon, tourmaline and rutile. Less stable accessories are apatite, staurolite and garnet. Standard heavy mineral analysis of samples from two study areas in central/northern (Tabuk area) and southern (Wajid area) Saudi Arabia reveals distinct changes in provenance. Cambrian-Ordovician sandstones are first-cycle sediments, probably sourced from the 'Pan-African' basement. The overlying Hirnantian glaciogenic deposits consist of recycled Cambrian-Ordovician material. Devonian-Permian sandstones show a significant influx of fresh basement material, as attested by an increase of meta-stable heavy minerals. Single-grain geochemical analysis of rutile and garnet has proven to be a powerful supplementary technique. Rutile varietal studies reveal distinct differences in host rock lithologies between the two study areas: the Tabuk area contains predominantly felsic rutiles, whereas the Wajid area has more mafic input. Zr-in-rutile thermometry identified granulite-facies detritus in the lower Palaeozoic of the Tabuk area and has the potential to further define source areas. The distribution patterns of garnet host rock lithologies are remarkably similar in both study areas. They are dominated by amphibolite-facies metasediments and intermediate to felsic igneous rocks. Garnets derived from granulite-facies metasediments, which are scarce in the Arabian-Nubian Shield, also occur. Possible source rocks for high-grade garnets can be found in Yemen or farther south in the Mozambique Belt.

  8. National Uranium Resource Evaluation: Marfa Quadrangle, Texas

    SciTech Connect

    Henry, C D; Duex, T W; Wilbert, W P

    1982-09-01

    The uranium favorability of the Marfa 1/sup 0/ by 2/sup 0/ Quadrangle, Texas, was evaluated in accordance with criteria established for the National Uranium Resource Evaluation. Surface and subsurface studies, to a 1500 m (5000 ft) depth, and chemical, petrologic, hydrogeochemical, and airborne radiometric data were employed. The entire quadrangle is in the Basin and Range Province and is characterized by Tertiary silicic volcanic rocks overlying mainly Cretaceous carbonate rocks and sandstones. Strand-plain sandstones of the Upper Cretaceous San Carlos Formation and El Picacho Formation possess many favorable characteristics and are tentatively judged as favorable for sandstone-type deposits. The Tertiary Buckshot Ignimbrite contains uranium mineralization at the Mammoth Mine. This deposit may be an example of the hydroauthigenic class; alternatively, it may have formed by reduction of uranium-bearing ground water produced during diagenesis of tuffaceous sediments of the Vieja Group. Although the presence of the deposit indicates favorability, the uncertainty in the process that formed the mineralization makes delineation of a favorable environment or area difficult. The Allen intrusions are favorable for authigenic deposits. Basin fill in several bolsons possesses characteristics that suggest favorability but which are classified as unevaluated because of insufficient data. All Precambrian, Paleozoic, other Mesozoic, and other Cenozoic environments are unfavorable.

  9. Origin of the Nubian and similar sandstones

    USGS Publications Warehouse

    McKee, E.D.

    1963-01-01

    The Nubian Sandstone and similar sandstone bodies exposed across much of northern Africa and adjoining parts of Asia are characteristically formed of clean sand that is conspicuously cross stratified throughout. Such sandstone, here called Nubian-type sandstone, ranges from Cambrian through Cretaceous in age and its genesis has been interpreted in many ways. Studies of its primary structures, and of the direction of sand transport, based on statistical measurements of foreset dip directions, have contributed new data on its genesis. By far the most common structure in Nubian-type sandstone is a medium-scale planar-type cross stratification in which sets of evenly dipping cross beds are bounded by essentially flat-lying top and bottom surfaces to form tabular bodies. Other less numerous but typical structures are large-scale, truncated-wedge cross strata, trough-type cross strata, intraformational recumbent folds, small-scale ripple laminae, and dipping sets of tabular-planar cross beds. An analysis of these structures suggests that in the typical Nubian Sandstone of Cretaceous age eolian deposits are not represented and normal marine types probably also are lacking; flood plain, pond or lagoon, and other continental and marginal environments are indicated. In the Carboniferous rocks of Sinai Peninsula some beach sandstone and possibly some eolian, in addition to the types described, form part of the sequence. Direction of sand transport, as determined from cross-bed dips, was northerly in the Cretaceous Nubian of Libya, Sudan, and Egypt; easterly in the Jurassic Adigrat of Ethiopia; westerly in the Carboniferous of Sinai; northwesterly in the early Paleozoic of Jordan. ?? 1963 Ferdinand Enke Verlag Stuttgart.

  10. Regional geological framework and petroleum geology of Miocene sandstones in coastal and offshore Alabama

    SciTech Connect

    Mancini, E.A.; Bearden, B.L.; Mink, R.M.

    1987-05-01

    The Miocene natural gas trend of coastal and offshore Alabama is part of the regional Miocene oil and gas trend of the Gulf coastal area that extends from Texas into Alabama. The major Miocene productive area in Alabama is in southern Baldwin County and Mobile Bay. Since the discovery of Miocene gas in 1979, 28 natural gas fields have been established in coastal and offshore Alabama. The Miocene sandstones range in thickness from 10 to 200 ft, are very fine to coarse grained, are quartz rich, and have subangular to rounded and moderately to well-sorted quartz grains. The productive Miocene interval overlies upper Oligocene marine shelf deposits (Chickasawhay Limestone) and is overlain by Miocene fluvial clastics. The Miocene sandstones, which include the Amos, Escambia, Luce, and Meyer, are interpreted to represent a marine shelf-deltaic complex. A Miocene delta system prograded from the west in the area of offshore Louisiana-Mississippi into coastal and offshore Alabama. Reservoirs and potential reservoirs include highly constructive and highly destructive deltaic and marine shelf sandstones. Porosity in these sandstones is primary intergranular and generally ranges from 27 to 35%. Permeabilities may exceed 2000 md. Basinal Miocene marine clays and Oligocene marls are the probable petroleum source rocks. Petroleum traps are principally stratigraphic, typically involving lateral sandstone pinch-outs against regional dip. Seismic reflection is an excellent exploration tool for identifying potential Miocene fields. Miocene gas sands are best delineated with relative-amplitude seismic reflection data on which gas-charged sands are apparent as bright spots.

  11. Electrofacies vs. lithofacies sandstone reservoir characterization Campanian sequence, Arshad gas/oil field, Central Sirt Basin, Libya

    NASA Astrophysics Data System (ADS)

    Burki, Milad; Darwish, Mohamed

    2017-06-01

    The present study focuses on the vertically stacked sandstones of the Arshad Sandstone in Arshad gas/oil field, Central Sirt Basin, Libya, and is based on the conventional cores analysis and wireline log interpretation. Six lithofacies types (F1 to F6) were identified based on the lithology, sedimentary structures and biogenic features, and are supported by wireline log calibration. From which four types (F1-F4) represent the main Campanian sandstone reservoirs in the Arshad gas/oil field. Lithofacies F5 is the basal conglomerates at the lower part of the Arshad sandstones. The Paleozoic Gargaf Formation is represented by lithofacies F6 which is the source provenance for the above lithofacies types. Arshad sediments are interpreted to be deposited in shallow marginal and nearshore marine environment influenced by waves and storms representing interactive shelf to fluvio-marine conditions. The main seal rocks are the Campanian Sirte shale deposited in a major flooding events during sea level rise. It is contended that the syn-depositional tectonics controlled the distribution of the reservoir facies in time and space. In addition, the post-depositional changes controlled the reservoir quality and performance. Petrophysical interpretation from the porosity log values were confirmed by the conventional core measurements of the different sandstone lithofacies types. Porosity ranges from 5 to 20% and permeability is between 0 and 20 mD. Petrophysical cut-off summary of the lower part of the clastic dominated sequence (i. e. Arshad Sandstone) calculated from six wells includes net pay sand ranging from 19.5‧ to 202.05‧, average porosity from 7.7 to 15% and water saturation from 19 to 58%.

  12. Multi-waveform classification for seismic facies analysis

    NASA Astrophysics Data System (ADS)

    Song, Chengyun; Liu, Zhining; Wang, Yaojun; Li, Xingming; Hu, Guangmin

    2017-04-01

    Seismic facies analysis provides an effective way to delineate the heterogeneity and compartments within a reservoir. Traditional method is using the single waveform to classify the seismic facies, which does not consider the stratigraphy continuity, and the final facies map may affect by noise. Therefore, by defining waveforms in a 3D window as multi-waveform, we developed a new seismic facies analysis algorithm represented as multi-waveform classification (MWFC) that combines the multilinear subspace learning with self-organizing map (SOM) clustering techniques. In addition, we utilize multi-window dip search algorithm to extract multi-waveform, which reduce the uncertainty of facies maps in the boundaries. Testing the proposed method on synthetic data with different S/N, we confirm that our MWFC approach is more robust to noise than the conventional waveform classification (WFC) method. The real seismic data application on F3 block in Netherlands proves our approach is an effective tool for seismic facies analysis.

  13. Evolution of Permian evaporite basin in Texas panhandle

    SciTech Connect

    Presley, M.W. )

    1987-02-01

    Permian (Leonardian to Ochoan) evaporites in the Texas Panhandle were deposited in a range of marine shelf to supratidal environments along an arid coastline. Carbonates in these strata generally were deposited in inner shelf systems and include subtidal to supratidal facies. Landward of shelf environments, evaporites were deposited in brine pans and salt flats. Brine-pan facies are laminated anhydrite and banded salt that formed in shallow, hypersaline water such as restricted lagoons or supratidal salines. Salt-flat facies are mainly chaotic mixtures of mudstone and halite possibly formed by salt deposition on and within mud flats that bordered brine pans, or in brine-soaked mud-flat depressions. Periodically, mud flats built across the evaporite systems and were supplied with red terrestrial clastics, mainly mud and silt. These facies occur together in at least three different types of lithogenetic units. Strata in the Clear Fork Group (Leonardian) are considered deposits of a coastal evaporite basin that was progressively filled by terrestrial clastics. These rocks exhibit regressive cycles of brine-pan, salt-flat, and mud-flat facies. In contrast, San Andres strata (Guadalupian) were deposited in a broad marine embayment with persistent brine-pan conditions, and contain cycles of inner shelf and brine-pan facies. Post-San Andres strata (late Guadalupian and Ochoan) were deposited in the inner reaches of a broad interior salt basin and are composed mainly of mud-flat, salt-flat, and halite-rich brine-pan facies. 20 figs., 2 tabs.

  14. Geometric and sedimentologic characteristic of Mid-Miocene lowstand reservoir sandstones, offshore northwest Java, Indonesia

    SciTech Connect

    Lowry, P.; Kusumanegara, Y.; Warman, S.

    1996-12-31

    Numerous reservoirs in the Upper Cibulakan Formation (Mid-Miocene) of the Offshore Northwest Java shelf occur in sharp-based sandbodies that range from less than 1 m up to 10 m in thickness. Well-log derived net-sand isopach and seismic amplitude maps of these sandbodies depict elongate features, that are 1-2 km wide and 5-8 km long. The orientation of the longest axis of these sandbodies is predominantly north-south. Conventional cores reveal that these sandbodies are burrowed to completely bioturbated sandstones. Common trace fossils associated with these sandbodies include Ophiomorpha, Teichichnus and Thalassinoides. The lower contact of these sands is typically sharp and is commonly associated with a Glossifungites surface and siderite mud clasts. Overlying and underlying mudstones are relatively devoid of burrowing. Benthonic foraminifera assemblages within these mudstones indicate inner to outer neritic conditions in a relatively restricted marine setting. The upper contact of these sandstones is gradational over a 0.5 to 1m interval. Sandbodies of the same age and similar facies were observed in outcrops in onshore west Java. Here, they can be observed to pinch out over a distance of 500 m. The lower bounding contact appears discordant with underlying interbedded sandstones and mudstones. Several of the sandstones contain abundant accumulations of the large, open marine, benthonic foraminifera Cycloclypeus and Lepidocyclina. Occasionally the concentration of these large foraminifera form limestones within the sharp-based sandbodies. These bioclastic deposits commonly exhibit planar-tabular and trough cross-stratification. The sandbodies are interpreted as having been emplaced during relative falls in sea-level within a large Mid-Miocene embayment. Our understanding of their geometry and sedimentologic characteristics is leading to a more effective exploitation strategy for these sandbodies in the Offshore Northwest Java area.

  15. Synsedimentary tectonics, distribution, and reservoir quality of Rotliegende sandstones: Emsland Province, northwest Germany

    SciTech Connect

    Kuehn, M. )

    1993-09-01

    The exploration for gas in the Rotliegende of the Emsland province, northwest Germany, has had very limited success so far. This fact is contrasted by less than 30 km distance to the giant Groningen gas field. Risks concerning Rotliegende hydrocarbon reservoirs in this area are (a) severe deterioration of permeability by widespread growth of illite in pore space and (b) absence of upper Rotliegende strata in certain areas. The Rotliegende of the Emsland was deposited in an embayment of the main west-northwest-east-southeast Rotliegende basin. Intensive growth of illite area. A southern part, about 50 km southward, with only limited well control in between, displays an erratic spatial distribution of clay- and sandstones. A total of 450-m conventional cores of 22 wells in the rotliegende were evaluated as to their sedimentary facies and petrography. A plateau basalt represents the lower Rotliegende, with a maximum thickness of 135 m. It was covered by a red-laminated claystone of up to 65 m thickness. After deposition of this claystone, a half-garben structure was formed, filled up with clean mature medium-grained sandstones up to 150 m thick, and deposited in a desert environment. Subsidence in the southern part ended after deposition of the so-called Haren sandstone, which is of good reservoir quality. The northern part continued to subside, and sandstones of a regressive lakeshore environment alternate with transgressive claystones. Erosion of the southern area is documented (a) in the distinct amount of detrital basalt fragments in the sands shedded to the north and (b) the absence of upper Rotliegende strata. We assume the composition of detritus, together with depth, to be the main factors creating illite growth in this northern area.

  16. Anatomy of an ancient aeolian sandstone on Mars: the Stimson formation, Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Gupta, Sanjeev; Banham, Steven; Rubin, David; Watkins, Jessica; Sumner, Dawn; Grotzinger, John P.; Lewis, Kevin; Edgett, Kenneth S.; Edgar, Lauren; Stack, Kathryn; Day, McKenzie; Ewing, Ryan; Lapotre, Mathieu

    2016-10-01

    Since landing in 2012, the Mars Science Laboratory's (MSL) rover Curiosity has traversed the plains and foothills of Aeolis Mons (informally known as Mt. Sharp) investigating the environments preserved in the stratigraphic record of Gale crater. Recently, the Curiosity team has been investigating the Stimson formation, a sandstone exhibiting abundant crossbedding that drapes the underlying Murray formation mudstones. The contact between the Stimson and underlying Murray formation exhibits several meters relief over several 100 m hundred metres where encountered thus far. The Stimson is observed to onlap onto this contact, indicating that accumulating Stimson sandstones unconformably onlapped or buried local palaeotopography.Facies and architectural elements observed within the Stimson are interpreted to represent deposition within an ancient dune field. The Stimson formation is typically composed of decimeter-scale and meter-scale crossbedded sandstones, (exhibiting wind-ripple lamination and well rounded particles up to granule size). Architectural elements are visible in outcrops oriented perpendicular to the regional northwest dip. These consist of undulating surfaces parallel to the regional dip with observed lateral extents up to 30 m that truncate underlying cross-sets and commonly act as basal surfaces to overlying cross-sets. Undulating surfaces are interpreted possibly to be deflationary supersurfaces, which formed in response to deflation or dune-field stabilisation across a regional extent. Surfaces inclined relative to the regional dip ascend between supersurfaces towards the north east at an observed angle of 3-4°. These surfaces are interpreted to be dune bounding surfaces, which are preserved when dunes climb as a result of dune-field aggradation. Aggradation of the system during the duration of the dune field's existence possibly occurred as a response to episodic increases of sediment supply into the basin, allowing dunes to climb and preserving

  17. New Perspectives on the Old Red Sandstone

    NASA Astrophysics Data System (ADS)

    Miall, Andrew D.

    The Old Red Sandstone is amongst the most distinctive and well-known stratigraphic units in the British Isles. It is mainly of Devonian age; in fact, its lower boundary was used to define the base of the Devonian until relatively recently and it was called "Old" back in the nineteenth century to distinguish it from a superficially similar succession of Triassic age named the New Red Sandstone. The Old Red Sandstone has long been known to be a non-marine syntectonic to post-tectonic deposit associated with the Caledonian Orogeny One of the most famous outcrops of the red sandstone is at Siccar Point in northeast England at one of several outcrops named "Hutton's unconformity" where it lies, with marked angularity on Silurian lithic sandstones and shales. It was at these outcrops, toward the end of the eigthteenth century that James Hutton first came to understand the meaning of angular unconformities as structures representing vast amounts of missing time during which major upheavals of the Earth's crust occurred.

  18. Facies analysis and sequence stratigraphy of the Cenomanian-Turonian mixed siliciclastic-carbonate sediments in west Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Anan, Tarek I.

    2014-06-01

    The unconformity bounded Cenomanian-Turonian succession in west Sinai is subdivided into three formations: the Raha, Abu Qada, and Wata. These rock units were deposited in a mixed siliciclastic-carbonate system on a ramp setting. The studied ramp only includes inner and mid-ramp facies, whereas the outer ramp facies occurs in northern Sinai. Four sequence boundaries (SB) were recognized in the studied formations due to the presence of subaerial exposure or flooding events in the facies stacking pattern. The first and last sequence boundaries (SB1 and SB4) might be considered as Type 1 sequence boundary attributable to the presence of widespread erosion. It is difficult to determine type of the second and third sequence boundaries (SB2 and SB3) because of their minor unconformity and minimal erosion. Determination of systems tracts within the Wata Formation is debatable owing to the action of dolomitization that has destroyed both original components and sedimentary structures. The lowstand systems tracts of the recorded sequences are characterized by sandstones, siltstones, and sandy shales, while fossiliferous shale and limestone with oysters prevailed during sea level rise. The highstand systems tracts are generally characterized by shallow intertidal and subtidal deposits that are made up of abundant oyster wackestones with benthic foraminifera and ostracods.

  19. Tidal-bundle sequences in the Jordan Sandstone (Upper Cambrian), southeastern Minnesota, U.S.A.: Evidence for tides along inboard shorelines of the Sauk Epicontinental Sea

    USGS Publications Warehouse

    Tape, C.H.; Cowan, Clinton A.; Runkel, Anthony C.

    2003-01-01

    This study documents for the first time tidal bundling in a lower Paleozoic sheet sandstone from the cratonic interior of North America, providing insights into the hydrodynamics of ancient epicontinental seas. The Jordan Sandstone (Upper Cambrian) in the Upper Mississippi Valley contains large-scale planar tabular cross-sets with tidal-bundle sequences, which were analyzed in detail at an exceptional exposure. Tidal-bundle sequences (neap-spring-neap cycles) were delineated by foreset thickening-thinning patterns and composite shale drapes, the latter of which represent accumulations of mud during the neap tides of neap-spring-neap tidal cycles. Fourier analysis of the bundle thickness data from the 26 measurable bundle sequences revealed cycles ranging from 15 to 34 bundles per sequence, which suggests a semidiurnal or mixed tidal system along this part of the Late Cambrian shoreline. We extend the tidal interpretation to widespread occurrences of the same facies in outcrops of lesser quality, where the facies is recognizable but too few bundles are exposed for tidal cycles to be measured. By doing so, this study shows that tidally generated deposits have a significant geographic and temporal extent in Upper Cambrian strata of central mid-continent North America. The deposition and preservation of tidal facies was related to the intermittent development of shoreline embayments during transgressions. The tidally dominated deposits filled ravined topographies that were repeatedly developed on the updip parts of the shoreface. Resulting coastal geomorphologies, accompanied perhaps by larger-scale changes in basinal conditions and/or configuration, led to changes in depositional conditions from wave-dominated to tide-dominated. Outcrops of the Jordan Sandstone tidal facies in the Upper Mississippi Valley represent the farthest inboard recorded transmission of ocean-generated tides in the Laurentian epicontinental seas, demonstrating that tidal currents were

  20. Geological Modeling and Fluid Flow Simulation of Acid Gas Storage, Nugget Sandstone, Moxa Arch, Wyoming

    NASA Astrophysics Data System (ADS)

    Li, S.; Zhang, Y.; Zhang, X.; Du, C.

    2009-12-01

    The Moxa Arch Anticline is a regional-scale northwest-trending uplift in western Wyoming where geological storage of acid gases (CO2, CH4, N2, H2S, He) from ExxonMobile's Shute Creek Gas Plant is under consideration. The Nugget Sandstone, a deep saline aquifer at depths exceeding 17,170 ft, is a candidate formation for acid gas storage. As part of a larger goal of determining site suitability, this study builds three-dimensional local to regional scale geological and fluid flow models for the Nugget Sandstone, its caprock (Twin Creek Limestone), and an underlying aquifer (Ankareh Sandstone), or together, the ``Nugget Suite''. For an area of 3000 square miles, geological and engineering data were assembled, screened for accuracy, and digitized, covering an average formation thickness of ~1700 feet. The data include 900 public-domain well logs (SP, Gamma Ray, Neutron Porosity, Density, Sonic, shallow and deep Resistivity, Lithology, Deviated well logs), 784 feet of core measurements (porosity and permeability), 4 regional geological cross sections, and 3 isopach maps. Data were interpreted and correlated for geological formations and facies, the later categorized using both Neural Network and Gaussian Hierarchical Clustering algorithms. Well log porosities were calibrated with core measurements, those of permeability estimated using formation-specific porosity-permeability transforms. Using conditional geostatistical simulations (first indicator simulation of facies, then sequential Gaussian simulation of facies-specific porosity), data were integrated at the regional-scale to create a geological model from which a local-scale simulation model surrounding the Shute Creek injection site was extracted. Based on this model, full compositional multiphase flow simulations were conducted with which we explore (1) an appropriate grid resolution for accurate acid gas predictions (pressure, saturation, and mass balance); (2) sensitivity of key geological and engineering

  1. Shoreline depositional environments of Glen Rose Formation (lower Cretaceous) in type area, Somervell and Hood Counties, Texas

    SciTech Connect

    Bergan, G.R.

    1988-09-01

    The studied interval of the Glen Rose Formation (Aptian-Albian) comprises a clastic-to-carbonate sequence, which was deposited in a seaward-fining tidal flat-salt marsh complex. Eight distinct facies were identified, including the calcareous sandstone, calcareous shale, bivalve shale, oyster shale, transitional terrigenous-carbonate, dolomite, bioclastic packstone-grainstone, and shell-fragment wackestone facies. These facies were deposited in sand flats; small fluvial creeks; an ecologically complex, mud-dominated intertidal flat; and a subtidal, nearshore lagoon. Thin bioclastic packstone-grainstones and dolomites of the high energy intertidal and supratidal environments regularly interrupt the terrigenous clastic facies. Abundant nearshore features include salt-tolerant land plants, dinosaur tracks, desiccation cracks, and localized concentrations of evaporites. A warm semi-arid to arid climate is indicated. This sequence is interpreted as being comparable to the Holocene salt marshes on Sapelo Island, Georgia, based on similar lithofacies, sedimentary structures, and biological components.

  2. Trace fossils and sedimentary facies from a Late Cambrian-Early Ordovician tide-dominated shelf (Santa Rosita Formation, northwest Argentina): Implications for ichnofacies models of shallow marine successions

    USGS Publications Warehouse

    Mangano, M.G.; Buatois, L.A.; Acenolaza, G.F.

    1996-01-01

    The Santa Rosita Formation is one the most widely distributed lower Paleozoic units of northwest Argentina. At the Quebrada del Salto Alto section, east of Purmamarca, Jujuy Province, it is represented by four sedimentary facies: thick-bedded planar cross-stratified quartzose sandstones (A), thin-bedded planar cross-stratified quartzose sandstones and mudstones (B), wave-rippled sandstones and bioturbated mudstones (C), and black and greenish gray shales (D). Paleocurrent data, sandstone architecture, and sedimentary structures from facies A and B indicate bipolar/bimodal paleoflows, suggesting the action of tidal currents. The succession is interpreted as that of a tide-dominated shelf, with only secondary influence of wave processes. Trace fossils are restricted to facies B and C. The Cruziana ichnocoenosis is preserved on the soles of thin-bedded planar cross-stratified quartzose sandstones (facies B). This ichnocoenosis consists of Conostichus isp., Cruziana omanica, C. semiplicata, C. cf. tortworthi, Cruziana isp. Helminthopsis abeli, Monomorphichnus bilinearis, M. multilineatus, Palaeophycus tubularis, Rusophycus carbonarius, R. latus, and R. isp. The occurrence of Cruziana semiplicata, C. omanica, C. cf. tortworthi, and Rusophycus latus supports a Late Cambrian-Tremadoc age. Slabbing of Cruziana shows complex interactions between biologic and sedimentologic processes, and suggests a predominance of exhumed traces, washed out and recast by tractive sand deposition. Sandstone soles are densely packed with biogenic structures and exhibit distinctive clusters of Rusophycus isp. that most likely represent trilobite nesting burrows. The Cruziana ichnocoenosis records the resident fauna of a protected, lower intertidal to subtidal interbar setting. The Skolithos ichnocoenosis is represented by high to low density vertical burrows of Skolithos linearis, which extend downwards to the quartzose sandstone soles of facies B and cross the Cruziana ichnocoenosis. The

  3. Facies distribution, heterogeneity study and numerical 3D modeling of a multilayered Rhaetian-Lower Cretaceous aquifer succession in the Höllviken Halfgraben, SW Skåne, Sweden - assessment of suitability for storage of CO2

    NASA Astrophysics Data System (ADS)

    Erlström, M.; Niemi, A.; Lindström, S.; Gunnarsson, N.; Daher, S. Bou

    2012-04-01

    Several variably thick sandstone beds are found within a 200-300 m thick Rhaetian-Lower Cretaceous succession in the Höllviken Halfgraben. Many of these are considered as potential aquifers for geothermal energy and possibly also for CO2 storage. One of the challenges in evaluating this potential lies within the task to assess the frequency and distribution patterns of the sandstone units in the multilayered succession. For this purpose biostratigraphic analyses, lithofacies investigations and numerical modeling have been conducted. The main part of the investigated succession along the margins of the Danish Basin, including the Höllviken Halfgraben reflects a highly dynamic coastline, which along with differential subsidence, and possible multiple sediment sources has resulted in a difficulty to correlate lithological units between boreholes. Four main lithofacies, of which one is fine-grained sandstone, are identified by use geophysical wire line logs and a few cored reference boreholes. The gradual transition between the identified lithofacies implies a genetic relation between the different facies, related to relative sea level fluctuation coupled with tectonic activity. This has, thus, yielded high degree of heterogeneity regarding distribution and frequency of the different facies. The four defined facies can be assigned to a tide dominated deltaic setting, which could further be divided into sub-environements based on proximity to the shoreline. There are only 2-3 sandstone units which have a regional distribution and that can be defined from a sequence stratigraphic analysis and correlated by use of the biostratigraphic results. The majority of beds have, however a local interfingering distribution pattern. A frequency study of the different facies in five wells indicate that the sandstone facies is more common adjacent to the bounding fault zones, thus indicating syndepositional surrounding highs generating eroded clastics entering the H

  4. Eolian sabkha sandstones in the Nugget Sandstone (Jurassic), Vernal area, Utah

    SciTech Connect

    Schenk, C.J.; Peterson, F. )

    1991-06-01

    The Jurassic Nugget Sandstone in the Vernal, Utah, area is characterized by thick (up to 25 m) sets of cross-stratified eolian dune sandstone separated by either erosional planar bounding surfaces or thin (mostly < 3 m) sandstones interpreted as sabkha sandstones. Structures in Nugget sabkha sandstones are predominantly wavy or irregular bedding and thin, remnant sets of dune cross-strata consisting of eolian ripple and avalanche strata. The types of sedimentary structures and erosional features in Nugget sabkha sandstones indicate a close relationship between sand deposition and erosion and fluctuations in the local water table. Thin, remnant eolian dune sets are common in Nugget sabkha sandstones. The remnant sets form when dunes migrating across a sabkha are partially wetted as the water table rises slightly (on a scale of tens of centimeters); the lower part of the dune with wetted sand remains on the sabkha as the rest of the dune continues to migrate. Typically, ripple strata of the dune apron and the toes of avalanche strata are preserved in dune remnants. The avalanche strata, being slightly coarser grained, are preferentially deflated, leaving microtopography. This topography is commonly filled in with ripple strata that form as dry sand again blows across the sabkha. Stacked sets of remnant dunes separated by erosional surfaces illustrate the control of sand deposition on eolian sabkhas by the local water table.

  5. TENET: Texas Education Network.

    ERIC Educational Resources Information Center

    Stout, Connie

    The Texas Education Agency sought to create an enhanced electronic communications network (TENET) capable of transmitting information among and between the members of the public education system in Texas. They contracted with the Texas Higher Education Network (THEnet), an existing distributed network which is an NSF (National Science Foundation)…

  6. Treasured Texas Theaters

    ERIC Educational Resources Information Center

    Horton, Anita

    2012-01-01

    Dallas artist Jon Flaming's deep love of Texas is evident in his paintings and sculpture. Although he has created one sculptural Texas theater, his work primarily showcases old Texas barbershops, vacant homes, and gas stations. In this article, the author describes how her students, inspired by Flaming's works, created three-dimensional historical…

  7. East Texas Storytellers.

    ERIC Educational Resources Information Center

    Anderson, Brandi, Ed.

    1987-01-01

    Written and published by the students at Gary High School, Gary, Texas, "Loblolly Magazine" is published twice a year. Issues are frequently devoted to a distant theme. The theme of this issue, "East Texas Storytellers," attempts to capture some of the local color and regional history of eastern Texas. The first article,…

  8. Treasured Texas Theaters

    ERIC Educational Resources Information Center

    Horton, Anita

    2012-01-01

    Dallas artist Jon Flaming's deep love of Texas is evident in his paintings and sculpture. Although he has created one sculptural Texas theater, his work primarily showcases old Texas barbershops, vacant homes, and gas stations. In this article, the author describes how her students, inspired by Flaming's works, created three-dimensional historical…

  9. East Texas Storytellers.

    ERIC Educational Resources Information Center

    Anderson, Brandi, Ed.

    1987-01-01

    Written and published by the students at Gary High School, Gary, Texas, "Loblolly Magazine" is published twice a year. Issues are frequently devoted to a distant theme. The theme of this issue, "East Texas Storytellers," attempts to capture some of the local color and regional history of eastern Texas. The first article,…

  10. An overview of the Cretaceous stratigraphy and facies development of the Yazd Block, western Central Iran

    NASA Astrophysics Data System (ADS)

    Wilmsen, Markus; Fürsich, Franz Theodor; Majidifard, Mahmoud Reza

    2015-04-01

    The Cretaceous successions of the Yazd Block, the western of three structural blocks of the Central-East Iranian Microcontinent (CEIM), have been studied using an integrated approach of litho-, bio- and sequence stratigraphy associated with litho-, bio- and microfacies analyses. The Cretaceous System of that area is in excess of 5 km thick and a generalized relative sea-level curve can be inferred from the facies and thickness development. This curve can be subdivided into two transgressive-regressive megacycles (TRMs), separated by a major tectonic unconformity in the Upper Turonian. TRM 1 comprises the Early Cretaceous to Middle Turonian, TRM 2 the Coniacian to Maastrichtian. TRM 1 starts with up to 1500-m-thick conglomerates and sandstones covering Palaeozoic-Triassic basement rocks, metasediments, or Upper Jurassic-lowermost Cretaceous granites. The basal tectonic unconformity, related to the Late Cimmerian event (Jurassic-Cretaceous boundary interval), shows a pronounced palaeo-relief that is levelled by the basal siliciclastic formations. Sparse biostratigraphic data from calcareous intercalations in the upper part of these strata indicate a Hauterivian to Barremian age. The Aptian facies development is marked by the onlap of thick-bedded, micritic carbonates with abundant orbitolinid foraminifera and rudists representing a large-scale shallow-marine carbonate platform system that fringed the Yazd Block in the north and west. These platforms are up to 1000 m thick and drowned during the middle to Late Aptian, followed by up to 1500-m-thick basinal marly sediments of Late Aptian to mid-Late Albian ages, representing the maximum relative sea-level during TRM 1. During the latest Albian-Middle Turonian, a gradual shallowing is indicated by progradation of shallow-water skeletal limestones separated by marl tongues, representing a carbonate ramp system. Strata of TRM 2 overlie older units along a regional angular unconformity and indicate tectonic stability and

  11. Tubiphytes-archaeolithoporella-girvanella reefal facies in Permian buildup, Mino terrane, central Japan

    NASA Astrophysics Data System (ADS)

    Sano, Hiroyoshi; Horibo, Kenji; Kumamoto, Yasuko

    1990-10-01

    The Lower to Middle Permian Okumino buildup of the Mino terrane, central Japan, formed a carbonate cap on a seamount which was sitting in an open-ocean realm. Microscopic examination reveals considerable amounts of Tubiphytes, Archaeolithoporella, and Girvanella in these rocks. These low laminar encrusting organisms together with cystopore bryozoa and syndepositional radial-fibrous cements formed bindstones. The bindstones are interpreted as having formed wave-resistant algal reefal mounds on the marginal terrace of the Okumino buildup which also has the lagoonal flat, sand bar or shoal, and foreslope facies. The Okumino buildup is closer in its biotic association of major encrusting organisms to the Trogkofel buildup in southern Alps than to the Capitan Reef Complex in New Mexico and Texas. The similarity implies that Tubiphytes and Archaeolithoporella were the most predominant and significant rock-forming encrusting organisms in Early to early Middle Permian times.

  12. Winnepegosis facies and reservoir characteristics, Temple field, North Dakota

    SciTech Connect

    Ehrets, J.R.; Kissling, D.L.

    1988-07-01

    Since its discovery in 1982, Temple field has been developed into the largest Winnipegosis oil pool in the Williston basin. Situated on a subordinate limb of the Nesson anticline in northeastern Williams County, the combined structural-stratigraphic trap contains approximately 7.5 million bbl of primary recoverable oil reserves defined by 22 productive wells. Dolomitized upper slope mudstone represents the principal reservoir facies. This facies is overlain by a poorly dolomitized platform-margin reef facies that serves as the reservoir seal. The Temple Winnipegosis reservoir is envisioned to have developed in response to late Winnipegosis sea level drawdown and widespread exposure of the carbonate platform. Confined between less permeable strata represented by underlying argillaceous slope facies and overlying reef facies, the nonargillaceous slope facies was dolomitized in a mixing zone created by downward and seaward movement of meteoric water into connate marine water. Early cementation of reef facies also served to limit brine invasion and salt plugging of the reservoir upon later transgression of the platform by the hypersaline Prairie sea. The slope reservoir is generally characterized by 12-20% porosity and 10-70 md permeability. By comparison, reef porosity is typically 2-8%, with less than 3 md permeability. Halite cement is a common constituent in reef facies, having precipitated from hypersaline brine that invaded the reef through a system of fractures and vugs. Halite cement is also responsible for partial reservoir destruction in the underlying slope reservoir, particularly where the reef is poorly developed.

  13. Coupling among Microbial Communities, Biogeochemistry, and Mineralogy across Biogeochemical Facies.

    PubMed

    Stegen, James C; Konopka, Allan; McKinley, James P; Murray, Chris; Lin, Xueju; Miller, Micah D; Kennedy, David W; Miller, Erin A; Resch, Charles T; Fredrickson, Jim K

    2016-07-29

    Physical properties of sediments are commonly used to define subsurface lithofacies and these same physical properties influence subsurface microbial communities. This suggests an (unexploited) opportunity to use the spatial distribution of facies to predict spatial variation in biogeochemically relevant microbial attributes. Here, we characterize three biogeochemical facies-oxidized, reduced, and transition-within one lithofacies and elucidate relationships among facies features and microbial community biomass, richness, and composition. Consistent with previous observations of biogeochemical hotspots at environmental transition zones, we find elevated biomass within a biogeochemical facies that occurred at the transition between oxidized and reduced biogeochemical facies. Microbial richness-the number of microbial taxa-was lower within the reduced facies and was well-explained by a combination of pH and mineralogy. Null modeling revealed that microbial community composition was influenced by ecological selection imposed by redox state and mineralogy, possibly due to effects on nutrient availability or transport. As an illustrative case, we predict microbial biomass concentration across a three-dimensional spatial domain by coupling the spatial distribution of subsurface biogeochemical facies with biomass-facies relationships revealed here. We expect that merging such an approach with hydro-biogeochemical models will provide important constraints on simulated dynamics, thereby reducing uncertainty in model predictions.

  14. Expert system for seismic facies interpretation in continental fault basin

    SciTech Connect

    Zhen, L.; Wanxuan, Z. )

    1992-01-01

    This paper reports on expert system for seismic facies interpretation in continental fault basins which is an intelligent interpretation tool that combines areal seismic stratigraphic theory with expert system principles. Seismic facies interpretation (sedimentary facies recovery) which is the essential of areal seismic stratigraphy involves some troubles: big data volume, many control factors, ambiguous interpretations and so on. An expert system, which acts as a real expert in the corresponding field, can make strict logic inference and draw reasonable conclusion of a complicated problem by using the rich knowledge and experience together with rigorous speciality theorems and regulations. This expert system is the explorative application of expert system to seismic facies interpretation. This expert system consists of a shell and a knowledgeable base. The shell includes three essential units: inference machine performing analysis and demonstration, user interface for information exchange between interpreter and the system, and the explanation module that describes inference procedure. The knowledge base stores up many informations: basin evolution stage, drilling lithological facies, seismic facies parameters, seismic facies pattern, depositional system and so forth. This expert system showed satisfactory function in interpreting seismic facies of north sag in Liaoxi depression in the Bohai Sea basin.

  15. Anatomy and dimensions of fluvial crevasse-splay deposits: Examples from the Cretaceous Castlegate Sandstone and Neslen Formation, Utah, U.S.A.

    NASA Astrophysics Data System (ADS)

    Burns, C. E.; Mountney, N. P.; Hodgson, D. M.; Colombera, L.

    2017-04-01

    Crevasse-splay deposits form a volumetrically significant component of many fluvial overbank successions (up to 90% in some successions).Yet the relationships between the morphological form of accumulated splay bodies and their internal facies composition remains poorly documented from ancient successions. This work quantifies lithofacies distributions and dimensions of exhumed crevasse-splay architectural elements in the Campanian Castlegate Sandstone and Neslen Formation, Mesaverde Group, Utah, USA, to develop a depositional model. Fluvial crevasse-splay bodies thin from 2.1 m (average) to 0.8 m (average) and fine from a coarsest recorded grain size of lower-fine sand to fine silt away from major trunk channel bodies. Internally, the preserved deposits of splays comprise laterally and vertically variable sandstone and siltstone facies associations: proximal parts are dominated by sharp and erosional-based sandstone-prone units, which may be structureless or may comprise primary current lineation on beds and erosional gutter casts; medial parts comprise sets of climbing-ripple strata and small scale deformed beds; distal parts comprise sets of lower-stage plane beds and complex styles of lateral grading into fine-grained floodbasin siltstones and coals. Lithofacies arrangements are used to establish the following: (i) recognition criteria for crevasse-splay elements; (ii) criteria for the differentiation between distal parts of crevasse-splay bodies and floodplain fines; and (iii) empirical relationships with which to establish the extent (ca. 500 m long by 1000 m wide) and overall semi-elliptical planform shape of crevasse-splay bodies. These relationships have been established by high-resolution stratigraphic correlation and palaeocurrent analysis to identify outcrop orientation with respect to splay orientation. This permits lateral changes in crevasse-splay facies architecture to be resolved. Facies models describing the sedimentology and architecture of

  16. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio fluvial-deltaic reservoirs of South Texas. Technical progress report, July 1--September 30, 1995

    SciTech Connect

    Tyler, N.; Levey, R.A.

    1995-10-10

    Advanced reservoir characterization techniques are being applied to selected reservoirs in the Frio fluvial-deltaic sandstone trend in order to maximize the economic producibility of resources in this mature oil play. More than half of the reservoirs in this play have already been abandoned, and large volumes of oil may remain unproduced unless advanced characterization techniques are applied to define untapped, incompletely drained, and new pool reservoirs as suitable targets for near-term recovery methods. This project is developing interwell-scale geological facies models and assessing engineering attributes of reservoirs in selected fields in order to characterize reservoir architecture, flow unit boundaries, and the controls that these characteristics exert on the location and volume of unrecovered mobile and residual oil. Phase 1 consisted of reservoir selection and initial framework characterization. Phase 2 involved advanced characterization to delineate incremental resource opportunities. Subtasks included volumetric assessments of untapped and incompletely drained oil along with an analysis of specific targets for recompletion and strategic infill drilling. The third phase of the project consists of documentation of Phase 2 results, technology transfer, and the extrapolation of specific results from reservoirs in this study to other heterogeneous fluvial-deltaic reservoirs within and beyond the Frio play in South Texas. Project work during this quarter consisted of (1) documentation of Phase 2 tasks associated with the delineation of untapped and incompletely drained reservoir compartments and new pool reservoirs in selected Frio fluvial-deltaic sandstone intervals in Rincon and Tijerina-Canales-Blucher fields, as well as (2) Phase 3 tasks related to the transfer of the technologies to industry that aided in delineation.

  17. Impact Metamorphism of Sandstones at Amguid Crater, Algeria

    NASA Astrophysics Data System (ADS)

    Sahoui, R.; Belhai, D.

    2016-08-01

    Amguid is a 450 m diameter sample crater; it is emplaced in Lower Devonian sandstones.We have carried out a petrographic study in order to investigate shock effects recorded in these sandstones and define shock stages in Amguid.

  18. Multiscale heterogeneity characterization of tidal channel, tidal delta and foreshore facies, Almond Formation outcrops, Rock Springs uplift, Wyoming

    SciTech Connect

    Schatzinger, R.A.; Tomutsa, L.

    1997-08-01

    In order to accurately predict fluid flow within a reservoir, variability in the rock properties at all scales relevant to the specific depositional environment needs to be taken into account. The present work describes rock variability at scales from hundreds of meters (facies level) to millimeters (laminae) based on outcrop studies of the Almond Formation. Tidal channel, tidal delta and foreshore facies were sampled on the eastern flank of the Rock Springs uplift, southeast of Rock Springs, Wyoming. The Almond Fm. was deposited as part of a mesotidal Upper Cretaceous transgressive systems tract within the greater Green River Basin. Bedding style, lithology, lateral extent of beds of bedsets, bed thickness, amount and distribution of depositional clay matrix, bioturbation and grain sorting provide controls on sandstone properties that may vary more than an order of magnitude within and between depositional facies in outcrops of the Almond Formation. These features can be mapped on the scale of an outcrop. The products of diagenesis such as the relative timing of carbonate cement, scale of cemented zones, continuity of cemented zones, selectively leached framework grains, lateral variability of compaction of sedimentary rock fragments, and the resultant pore structure play an equally important, although less predictable role in determining rock property heterogeneity. A knowledge of the spatial distribution of the products of diagenesis such as calcite cement or compaction is critical to modeling variation even within a single facies in the Almond Fin. because diagenesis can enhance or reduce primary (depositional) rock property heterogeneity. Application of outcrop heterogeneity models to the subsurface is greatly hindered by differences in diagenesis between the two settings. The measurements upon which this study is based were performed both on drilled outcrop plugs and on blocks.

  19. Reservoir characterization through facies analysis of core and outcrop of the Lower Green River Formation: Hydrocarbon production enhancement in the Altamont-Bluebell Field, Uinta Basin, Utah

    SciTech Connect

    Wegner, M.; Garner, A.; Morris, T.H.

    1995-06-01

    The Altamont-Bluebell Field has produced over 125 million barrels of oil from lacustrine rocks of the Green River Formation, yet operators have not been able to accurately distinguish productive zones from non-productive, thief, and water-bearing zones. Low recoverability is largely due to the lack of understanding of the relationship between heterolithic facies, reservoir fracture systems and clay migration. These areas were investigated by analyzing over 457 meters of core from the Bluebell area and 843 meters of outcrop from the Willow Creek area. Approximately 60% of the core consists of carbonates and 40% consists of clastics (predominantly sandstones). The carbonate rocks in general have good porosity and randomly oriented, interconnected fractures, whereas the fractures in the sandstones are more vertical and isolated. The sandstones, however, do have the best reservoir capacity due to inherent interparticle porosity. Preliminary analysis of clay types indicates swelling illite-smectite mixed layer clays as well as kaolinite in both the elastic and carbonate rocks. These swelling clay types combine with the high pour point waxy oils to reduce production efficiency and total recovery. Outcrop studies conducted in the Willow Creek Canyon area help establish facies heterogeneity and reservoir storage capacity of lithology within the facies belts that have been defined in the Altamont-Bluebell field. Although production primarily occurs from fractured lithology, core plug analyses of more than 10 lithology indicate that arenites have the greatest potential for reservoir capacity, with porosities as high as 27%. This suggests that an association of arenites with fractured lithology would provide the best scenario for long-term production.

  20. Fractures and stresses in Bone Spring sandstones

    SciTech Connect

    Lorenz, J.C.; Warpinski, N.R.; Sattler, A.R.; Northrop, D.A.

    1990-09-01

    This project is a collaboration between Sandia National Laboratories and Harvey E. Yates Company being conducted under the auspices of the Oil Recovery Technology Partnership. The project seeks to apply perspectives related to the effects of natural fractures, stress, and sedimentology to the simulation and production of low-permeability gas reservoirs to low-permeability oil reservoirs as typified by the Bone Spring sandstones of the Permian Basin, southeast New Mexico. This report presents the results and analysis obtained in 1989 from 233 ft of oriented core, comprehensive suite of logs, various in situ stress measurements, and detailed well tests conducted in conjunction with the drilling of two development wells. Natural fractures were observed in core and logs in the interbed carbonates, but there was no direct evidence of fractures in the sandstones. However, production tests of the sandstones indicated permeabilities and behavior typical of a dual porosity reservoir. A general northeast trend for the maximum principal horizontal stress was observed in an elastic strain recovery measurements and in strikes of drilling-induced fractures; this direction is subparallel to the principal fracture trend observed in the interbed carbonates. Many of the results presented are believed to be new information for the Bone Spring sandstones. 57 figs., 18 tabs.

  1. Differential Erosion at Work on Martian Sandstones

    NASA Image and Video Library

    2014-03-24

    Sandstone layers with varying resistance to erosion are evident in this Martian scene recorded by the Mast Camera on NASA Curiosity Mars rover on Feb. 25, 2014, about one-quarter mile about 400 meters from a planned waypoint called the

  2. Spectral Induced Polarization of Sandstones: Temperature Effects

    NASA Astrophysics Data System (ADS)

    Binley, A.; Kruschwitz, S.; Lesmes, D.

    2007-12-01

    There is growing interest in the use of spectral induced polarization (SIP) for a wide range of environmental applications, in particular those focused on hydrogeological investigations. Recent experimental work has demonstrated that the mean relaxation time of electrical impedance spectra measured in sandstones is linked to the grain surface area and strongly correlated to some measure of a dominant pore throat size. Such empirically derived relationships lead to potential models of SIP - hydraulic conductivity, which has immense value for the hydrological community. Furthermore, the links between surface area and electrical response may lead to other, equally exciting, applications, such as in characterizing geochemical reactivity of sediments. However, there is a need to understand the fundamental behavior of SIP in such porous media in order for such models to be applied usefully. In an attempt to address this, we focus here on the influence of temperature on the SIP behavior of a range of sandstones. Classical models of dielectric dispersion in colloids have proposed direct inverse relationships between relaxation time and temperature. Through a series of experimental trials we have studied this behavior: examining the impedance spectra (in the 1 mHz to 1 kHz range) of four different sandstones over a temperature range of 5 to 30 degrees Celsius. Analysis of the spectra with the widely used Pelton Cole-Cole model has confirmed hypothesized effects on a mean relaxation time but revealed that the responses to temperature change is a function of physical properties of the sandstone. In addition, the analysis has illustrated how temperature effects on surface complex conductivity of the sandstones differ as a function of pore fluid and formation factor. The results add to the growing experimental evidence of controls on spectral impedance in porous media and help ascertain generalized petrophysical models for a wide range of applications.

  3. Carbonate reservoirs deposited during sea level lowstands, Permian basin: Occurrence, geometry, facies, and origin of porosity of in-situ buildups

    SciTech Connect

    Mazzullo, S.J. ); Reid, A.M.; Reid, S.T.

    1990-02-01

    Carbonate reservoirs composed of in-situ reefs and associated facies, mostly deposited basinward of shallow platforms during sea level lowstands, are common in Pennsylvanian rocks in the Permian basin. Specific examples include some Atokan and Strawn fields in the Delaware basin, and Canyon-Cisco fields in the Midland basin. Such reservoirs are conspicuous by their absence in Permian rocks, where lowstand facies are instead siliciclastics and detrital carbonates. In-situ lowstand carbonate reservoirs are represented by phylloid algal reefs (Atokan, Canyon-Cisco), crinoid banks locally with some Chaetetes and phylloid algal reefs (Strawn), and bryozoan-algal boundstone reefs (Canyon-Cisco). These facies are associated with bioclastic and, locally, oolitic sandstones. Lowstand reservoirs are both underlain and overlain by deep-water facies, and field geometries range from equidimensional to slightly elongate, generally parallel to platform margins. Porosity in many fields is due to extensive leaching and karsting accompanying subaerial or shallow subsurface meteoric exposure. Accordingly, porosity predictions are best based on knowledge of reconstructed sea level curves. However, many reservoir pore systems have resulted from deep-burial dissolution accompanying chemical compaction and the migration of fluids out of the basin. Porosity predictions in such cases must rely on knowledge of diagenesis and aspects of basin hydrodynamics.

  4. Read Across Texas! 2002 Texas Reading Club Manual.

    ERIC Educational Resources Information Center

    Edgmon, Missy; Ferate-Soto, Paolo; Foley, Lelana; Hager, Tina; Heard, Adriana; Ingham, Donna; Lopez, Nohemi; McMahon, Dorothy; Meyer, Sally; Parrish, Leila; Rodriguez-Gibbs, Josefina; Moreyra-Torres, Maricela; Travis, Gayle; Welch, Willy

    The goal of the Texas Reading Club is to encourage the children of Texas to become library users and lifelong readers. This manual was created for the 2002 Texas Reading Club, a program of the Texas State Library and Archives Commission. The theme, "Read Across Texas!" invites children to explore the history, geography, and culture of…

  5. Eccentricity and precession forced cyclicity in the Upper Silurian Williamsport Sandstone Member of the Wills Creek Formation

    SciTech Connect

    Shelton, S.D.; Anderson, E.J. . Dept. of Geology)

    1993-03-01

    The Williamsport Sandstone Member, located at the base of the Wills Creek Formation, contains a complete 5th order sequence, traceable for more than 100 kilometers. This 5th order sequence is initiated with a massive iron-rich sandstone unit. The upper iron-rich sand of the Williamsport Member marks the beginning of the next 5th order sequence. The first 5th order rock cycle, interpreted as the product of the 100 k.y. Milankovitch eccentricity cycle, is divisible into five meter-scale 6th order precessional cycles (PACs). At Cedar Cliff, Maryland, the lithology of each of the five 6th order cycles is distinct. The first cycle (.8m thick) is a massive iron-rich sandstone. The second cycle (.75m thick) is an argillaceous nodular micrite. The third cycle (.75m thick) consists totally of thin-bedded quartz sandstone. The fourth cycle (2m thick) is represented by bedded limestones that thicken upward. The fifth cycle (.6m thick) is very thin-bedded to nodular limestone. This 5th order sequence and most of its internal cyclic elements can be traced over 100 kilometers to Mount Union, Pennsylvania where its facies are largely non-marine. Detailed correlation of these 6th order cycles reveals that the uppermost PAC is missing at Cumberland and Mount Union. At these localities, the prominent iron bed of the next 5th order sequence rests unconformably on the fourth PAC in the sequence. The fifth 6th order cycle was either not deposited or removed by erosion at these proximal localities. The laterally traceable hierarchic cyclic structure in the Williamsport Sandstone is consistent with the Milankovitch forcing model and provides a detailed stratigraphic basis for analysis of lateral patterns of cyclic accumulation in the late Silurian of the central Appalachians.

  6. Quaternary alluvial deposits of Wadi Gaza in the middle of the Gaza Strip (Palestine): Facies, granulometric characteristics, and their paleoflow direction

    NASA Astrophysics Data System (ADS)

    Ubeid, Khalid Fathi

    2016-06-01

    The Quaternary rocks of the Gaza Strip mainly consist of clastic sedimentary rocks. In Wadi Gaza, the outcropping rocks consist of brownish fine-grained deposits, sandstones, and conglomerates. The deposits have been studied from a genetic point of view, and six facies have been described: (i) graded clast-supported conglomerates, (ii) cross-bedded clast-supported conglomerates, (iii) sandy matrix conglomerates, (iv) cross-laminated medium-grained sandstones, (v) graded coarse-grained sandstones, and (vi) massive sandstones. The field work observations and granulometric analysis show that the sphericity of the grains increase toward the west, where its value ranges from ∼0.64 in the east to ∼0.70 in the west. In addition, the grain forms tend to be disc shape in the east, whereas they tend to be disc-to spheroid shape in the west, and they become well rounded to well sorted toward the west. Moreover, the features, geometry, and spatial relationship among these facies suggest that the Wadi Gaza was meandering wadi fed from Beir Sheva and the Northern Negev in the southeast of Gaza Strip through Wadi Al Shallala and Wadi Sheneq and from Hebron mountains in the West Bank at the east through Wadi Al Shari'a alluvials. Within the Gaza Strip, paleocurrent data ranges from 210° to 310°, indicating a mean a paleoflow direction to the W (276°) and a median value about 275°. The sedimentary rocks in the Wadi Gaza are considered to be deposited in two periods of climate conditions: the coarse-grained rocks were deposited during the period of wet condition before 12.4 ka age, whereas the eolinite fine-grained rocks were deposited during semiarid climate conditions which are younger in age than 12.4 ka.

  7. Seismic facies interpretation of Mesozoic sequences, Shiwandashan basin, China

    SciTech Connect

    Leu, Leikuang; Armentrout, J.M.; Faz, J.J. )

    1991-03-01

    Integration of outcrop and subsurface geologic data with seismic facies analysis identified three exploration plays in Shiwandashan basin, southeastern China: Triassic Submarine Fan: Elongate-mounded packages of variable amplitude, discontinuous, nonparallel reflections occur basinward of the slope and are downlapped by prograding slope clinoforms. This facies is undrilled. Basin modeling suggests the mounded seismic facies correlates with outcrops of Triassic marine siliclastic turbidites which grade laterally into basinal mudstone/limestone couplets. Triassic Shelf Carbonates: Localized, high amplitude parallel reflections occur in a retrograde succession at the top of the Triassic prograding clinoform. These high amplitude seismic facies are calibrated with drilled carbonate facies and are correlated with outcrops of upper Triassic shelf and shelf-edge reefs that contain two generations of migrated hydrocarbons. Jurassic Fan Deltas: Thick northeast-southwest bidirectional downlapping hummocks of variable amplitude reflections and intersecting northwest downlapping clinoforms form large mounds and grade laterally to moderately continuous parallel reflections. The hummocky-clinoform mound facies is calibrated by drilled, poorly sorted conglomerates and correlates with outcrops of a Jurassic synrift basin-fill succession. These Jurassic rocks are interpreted as fan-deltas grading laterally to sandy fluvial and shaley lacustrine facies. The geochemical data suggest a potential gas-prone play for the Triassic submarine fans and potential oil-prone play for the stratigraphically shallower Triassic shelf and shelf-edge reefs. The Jurassic fan delta play drilled tight with no hydrocarbons.

  8. Coupling among Microbial Communities, Biogeochemistry, and Mineralogy across Biogeochemical Facies

    SciTech Connect

    Stegen, James C.; Konopka, Allan; McKinely, Jim; Murray, Christopher J.; Lin, Xueju; Miller, Micah D.; Kennedy, David W.; Miller, Erin A.; Resch, Charles T.; Fredrickson, Jim K.

    2016-07-29

    Physical properties of sediments are commonly used to define subsurface lithofacies and these same physical properties influence subsurface microbial communities. This suggests an (unexploited) opportunity to use the spatial distribution of facies to predict spatial variation in biogeochemically relevant microbial attributes. Here, we characterize three biogeochemical facies—oxidized, reduced, and transition—within one lithofacies and elucidate relationships among facies features and microbial community biomass, diversity, and community composition. Consistent with previous observations of biogeochemical hotspots at environmental transition zones, we find elevated biomass within a biogeochemical facies that occurred at the transition between oxidized and reduced biogeochemical facies. Microbial diversity—the number of microbial taxa—was lower within the reduced facies and was well-explained by a combination of pH and mineralogy. Null modeling revealed that microbial community composition was influenced by ecological selection imposed by redox state and mineralogy, possibly due to effects on nutrient availability or transport. As an illustrative case, we predict microbial biomass concentration across a three-dimensional spatial domain by coupling the spatial distribution of subsurface biogeochemical facies with biomass-facies relationships revealed here. We expect that merging such an approach with hydro-biogeochemical models will provide important constraints on simulated dynamics, thereby reducing uncertainty in model predictions.

  9. Coupling among Microbial Communities, Biogeochemistry, and Mineralogy across Biogeochemical Facies

    NASA Astrophysics Data System (ADS)

    Stegen, James C.; Konopka, Allan; McKinley, James P.; Murray, Chris; Lin, Xueju; Miller, Micah D.; Kennedy, David W.; Miller, Erin A.; Resch, Charles T.; Fredrickson, Jim K.

    2016-07-01

    Physical properties of sediments are commonly used to define subsurface lithofacies and these same physical properties influence subsurface microbial communities. This suggests an (unexploited) opportunity to use the spatial distribution of facies to predict spatial variation in biogeochemically relevant microbial attributes. Here, we characterize three biogeochemical facies—oxidized, reduced, and transition—within one lithofacies and elucidate relationships among facies features and microbial community biomass, richness, and composition. Consistent with previous observations of biogeochemical hotspots at environmental transition zones, we find elevated biomass within a biogeochemical facies that occurred at the transition between oxidized and reduced biogeochemical facies. Microbial richness—the number of microbial taxa—was lower within the reduced facies and was well-explained by a combination of pH and mineralogy. Null modeling revealed that microbial community composition was influenced by ecological selection imposed by redox state and mineralogy, possibly due to effects on nutrient availability or transport. As an illustrative case, we predict microbial biomass concentration across a three-dimensional spatial domain by coupling the spatial distribution of subsurface biogeochemical facies with biomass-facies relationships revealed here. We expect that merging such an approach with hydro-biogeochemical models will provide important constraints on simulated dynamics, thereby reducing uncertainty in model predictions.

  10. Coupling among Microbial Communities, Biogeochemistry, and Mineralogy across Biogeochemical Facies

    PubMed Central

    Stegen, James C.; Konopka, Allan; McKinley, James P.; Murray, Chris; Lin, Xueju; Miller, Micah D.; Kennedy, David W.; Miller, Erin A.; Resch, Charles T.; Fredrickson, Jim K.

    2016-01-01

    Physical properties of sediments are commonly used to define subsurface lithofacies and these same physical properties influence subsurface microbial communities. This suggests an (unexploited) opportunity to use the spatial distribution of facies to predict spatial variation in biogeochemically relevant microbial attributes. Here, we characterize three biogeochemical facies—oxidized, reduced, and transition—within one lithofacies and elucidate relationships among facies features and microbial community biomass, richness, and composition. Consistent with previous observations of biogeochemical hotspots at environmental transition zones, we find elevated biomass within a biogeochemical facies that occurred at the transition between oxidized and reduced biogeochemical facies. Microbial richness—the number of microbial taxa—was lower within the reduced facies and was well-explained by a combination of pH and mineralogy. Null modeling revealed that microbial community composition was influenced by ecological selection imposed by redox state and mineralogy, possibly due to effects on nutrient availability or transport. As an illustrative case, we predict microbial biomass concentration across a three-dimensional spatial domain by coupling the spatial distribution of subsurface biogeochemical facies with biomass-facies relationships revealed here. We expect that merging such an approach with hydro-biogeochemical models will provide important constraints on simulated dynamics, thereby reducing uncertainty in model predictions. PMID:27469056

  11. Furthering Medical Education in Texas.

    PubMed

    Varma, Surendra K; Jennings, John

    2016-02-01

    Medical education in Texas is moving in the right direction. The Texas Medical Association has been a major partner in advancing medical education initiatives. This special symposium issue on medical education examines residency training costs, the Next Accreditation System, graduate medical education in rural Texas, Texas' physician workforce needs, the current state of education reform, and efforts to retain medical graduates in Texas.

  12. Stratigraphy and depositional environment of nonmarine facies of Frontier Formation, Eastern Pioneer Mountains, southwestern Montana

    USGS Publications Warehouse

    Dyman, T.S.; Tysdal, R.G.

    1998-01-01

    The Upper Cretaceous Frontier Formation in the eastern Pioneer Mountains of southwestern Montana was deposited in nonmarine environments west of the Western Interior Seaway within the Cordilleran foreland basin. These rocks have been assigned to the Frontier because they contain lithologies typical of the Frontier in the region even though they are entirely nonmarine and are thicker than the correlative marine Frontier to the east. The Frontier in the eastern Pioneer Mountains is underlain by the Vaughn Member of the Blackleaf Formation, but the upper part of the Frontier has been eroded and locally is overlain by rocks of Tertiary age. Geologic mapping was conducted and four sections were measured and described to determine facies, thickness variations, and depositional environments. In the eastern Pioneer Mountains study area, the Frontier ranges in thickness from about 1200 ft (366 m) in the south to more than 3400 ft (1036 m) in the north\\. Frontier strata in the study area cannot be readily subdivided into mappable units, but two broadly-defined informal lithic units are described. The lower unit contains yellow-brown weathering siltstone, mudstone, and fine-grained quartz-rich sandstone, and is about 250 ft (76 m) thick. The upper unit is composed of yellow-brown to dark-gray siltstone and mudstone, quartz- and chert-rich sandstone, conglomeratic sandstone, and limestone, and is more than 2100 ft (640 m) thick in one measured section. The lower contact of the Frontier is placed at the top of a porcellanite bed that is associated with maroon mudstone and siltstone, limestone, and calcareous dark-gray shale in the underlying Vaughn Member of the Blackleaf Formation. The porcellanite bed directly overlies the highest maroon mudstone-siltstone bed of the upper Vaughn. The Frontier Formation in the eastern Pioneer Mountains was deposited on a broad delta plain dominated by fine-grained sediments. Sandstones exhibit characteristics of anastomosing fluvial channels

  13. Geologic observations of the Whirlpool Sandstone in Western Warren County, Pennsylvania

    SciTech Connect

    Ensign, J. )

    1991-08-01

    The Whirlpool Sandstone represents the lowest member of the Lower Silurian Medina Group. The sandstone is ubiquitous in western New York and northwestern Pennsylvania, but economic development is difficult to predict and locate on a consistent basis. This reservoir appears to be composed of a basal beach sand, which in some areas is overlain by what appears to be prograding tidal/channel facies. Gross sequence of strata maps and unique vertical-profile maps have been helpful in reconstructing the depositional history of this reservoir. Porosity-foot maps have been very helpful for most development drilling decisions. Detailed cross sections have also provided valuable insight regarding subtle, but important, structural trends. Sonic logs and QLA2 logging software have helped to accurately determine that the cementation exponent is lower than 2.0, which is thought to be characteristic of intergranular porosity. This has justified recompletions in some areas where the Whirlpool was originally not completed due to overly pessimistic water saturations. A multiple regression equation has been used to identify those parameters possessing the highest degrees of correlation when compared to reserves. The maximum value for r-squared was 0.66. The equation-generated reserves were compared against decline-curve reserves and the results were extremely close, suggesting that the regression equations could be used to predict lifetime reserves even before the well is completed. However, since the independent variables are geographically sensitive, this equation can be used only in very specific areas.

  14. Fault control of channel sandstones in Dakota Formation, southwest Powder River basin, Wyoming

    SciTech Connect

    Moore, W.R.

    1983-08-01

    The Dakota Formation is an important oil reservoir in the southwestern Powder River basin and adjoining Casper arch. Two fields, Burke Ranch and South Cole Creek, are used as examples to show the depositional environments of the Dakota and to indicate the influence of tectonic control on the distribution of the environments. Burke Ranch field is a stratigraphic trap which produces oil from the upper bench of the Dakota. The environment of deposition of the reservoir, determined by subsurface analysis, is a channel sandstone. South Cole Creek field is a structural-stratigraphic trap which produces from the lower bench of the Dakota. Two distinct facies, a channel and channel margin sandstone, exist at South Cole Creek. At both Burke Ranch and South Cole Creek it can be shown that the Dakota channels were deposited on the downthrown side of faults, which were present during Dakota time and which now are reflected on the surface by drainage patterns. An understanding of the environments of deposition of the Dakota and control of the environments by paleotectonics is necessary for exploration for these prolific reservoirs.

  15. Sequence stratigraphy of the Aux Vases Sandstone: A major oil producer in the Illinois basin

    USGS Publications Warehouse

    Leetaru, H.E.

    2000-01-01

    The Aux Vases Sandstone (Mississippian) has contributed between 10 and 25% of all the oil produced in Illinois. The Aux Vases is not only an important oil reservoir but is also an important source of groundwater, quarrying stone, and fluorspar. Using sequence stratigraphy, a more accurate stratigraphic interpretation of this economically important formation can be discerned and thereby enable more effective exploration for the resources contained therein. Previous studies have assumed that the underlying Spar Mountain, Karnak, and Joppa formations interfingered with the Aux Vases, as did the overlying Renault Limestone. This study demonstrates that these formations instead are separated by sequence boundaries; therefore, they are not genetically related to each other. A result of this sequence stratigraphic approach is the identification of incised valleys, paleotopography, and potential new hydrocarbon reservoirs in the Spar Mountain and Aux Vases. In eastern Illinois, the Aux Vases is bounded by sequence boundaries with 20 ft (6 m) of relief. The Aux Vases oil reservoir facies was deposited as a tidally influenced siliciclastic wedge that prograded over underlying carbonate-rich sediments. The Aux Vases sedimentary succession consists of offshore sediment overlain by intertidal and supratidal sediments. Low-permeability shales and carbonates typically surround the Aux Vases reservoir sandstone and thereby form numerous bypassed compartments from which additional oil can be recovered. The potential for new significant oil fields within the Aux Vases is great, as is the potential for undrained reservoir compartments within existing Aux Vases fields.

  16. Reservoir heterogeneity in Carboniferous sandstone of the Black Warrior basin. Final report

    SciTech Connect

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

    1994-04-01

    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  17. Reservoir heterogeneity in carboniferous sandstone of the Black Warrior basin. Final report

    SciTech Connect

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

    1994-06-01

    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  18. Coal facies studies in the eastern United States

    USGS Publications Warehouse

    Hower, J.C.; Eble, C.F.

    2004-01-01

    Coals in the eastern United States (east of the Mississippi River) have been the subject of a number of coal facies studies, going back to the 19th century. Such studies would not necessarily fall within a strict modern classification of coal facies studies, but if a study encompassed some aspects of paleobotany, palynology, petrology, geochemistry, or sedimentology, we assumed that some data and interpretations may be of use in evaluations of the facies. References are presented, as a guide for further research, with annotation in the tables. ?? 2004 Elsevier B.V. All rights reserved.

  19. Sequence stratigraphy and facies associations of Falher units C and D, lower Cretaceous, Alberta Basin, Canada

    SciTech Connect

    Casas, J.E.; Walker, R.G.

    1996-08-01

    The Lower Cretaceous Falher Member (Spirit River Formation) in the Deep Basin of Alberta is composed of 5 units (A-E) comprising the reservoir of the giant Elmworth gas field. Using high resolution sequence stratigraphy, 333 well logs and 65 cores were integrated to understand the evolution of Falher C and D in the study area. Five major faces associations were defined in each unit. The basal surface of Falher D overlies nonmarine deposits (Falher E) and is defined by a marine flooding surface (transgressive surface of erosion) partially modified by a subsequent regressive surface of erosion. Southward, all the facies become more continental and the marine flooding surface passes into a lagoon-on-nonmarine contact. Falher D contains a series of shingled marine sandstone lenses separated by erosional surfaces interpreted as seaward-dipping ravinement surfaces indicating different phases of marine transgression-regression. The Falher C basal surface is a marine flooding surface partially modified by a regressive surface of erosion. The top of Falher C is defined by a marine flooding surface representing an increase in water depth and erosional truncation during shoreface retreat. Falher C is characterized in the south by floodplain deposits and progradational shoreface sediments deposited during high- stand. A relative sea level fail produced a sequence boundary and a seaward shift of the shoreface facies northward. A sea level rise caused the shoreface migration southward (landward), forming a new transgressive surface. Progradational shoreface deposits took place during highstand and the uppermost part of Falher C was filled by aggradational floodplain deposits.

  20. Reservoir uncertainty, Precambrian topography, and carbon sequestration in the Mt. Simon Sandstone, Illinois Basin

    USGS Publications Warehouse

    Leetaru, H.E.; McBride, J.H.

    2009-01-01

    Sequestration sites are evaluated by studying the local geological structure and confirming the presence of both a reservoir facies and an impermeable seal not breached by significant faulting. The Cambrian Mt. Simon Sandstone is a blanket sandstone that underlies large parts of Midwest United States and is this region's most significant carbon sequestration reservoir. An assessment of the geological structure of any Mt. Simon sequestration site must also include knowledge of the paleotopography prior to deposition. Understanding Precambrian paleotopography is critical in estimating reservoir thickness and quality. Regional outcrop and borehole mapping of the Mt. Simon in conjunction with mapping seismic reflection data can facilitate the prediction of basement highs. Any potential site must, at the minimum, have seismic reflection data, calibrated with drill-hole information, to evaluate the presence of Precambrian topography and alleviate some of the uncertainty surrounding the thickness or possible absence of the Mt. Simon at a particular sequestration site. The Mt. Simon is thought to commonly overlie Precambrian basement granitic or rhyolitic rocks. In places, at least about 549 m (1800 ft) of topographic relief on the top of the basement surface prior to Mt. Simon deposition was observed. The Mt. Simon reservoir sandstone is thin or not present where basement is topographically high, whereas the low areas can have thick Mt. Simon. The paleotopography on the basement and its correlation to Mt. Simon thickness have been observed at both outcrops and in the subsurface from the states of Illinois, Ohio, Wisconsin, and Missouri. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  1. Sedimentology, diagenesis, and trapping style, Chesterian Tar Springs sandstone at Inman Field, Gallatin County, Illinois

    SciTech Connect

    Morse, D.G.

    1996-09-01

    The Tar Springs Sandstone in southern Illinois is often over-looked as a pay, yet it can be a prolific producer. The Inman Field, discovered in 1940, produces from several cyclic Chesterian sandstones from structural-stratigraphic traps in the Wabash Valley Fault System of southeastern Illinois. The oil was sourced from the Devonian New Albany Shale and apparently migrated vertically along the Wabash Valley faults to its present location, thus charging many of the Chesterian and lower Pennsylvanian sands in the field. The Tar Springs Sandstone produces from stacked distributary channel sand reservoirs up to 125 feet thick which have cut up to 40 feet into laterally equivalent non-reservoir, delta-fringe facies and the underlying Glen Dean Limestone. The reservoir sands are well-sorted, fine- to medium-grained quartz arenites with less than 5% feldspar and chert. Quartz grains have quartz overgrowths. Feldspar grains are clouded in thin-section and show pronounced etching and dissolution in SEM. Diagenetic kaolinite and small amounts of illite and magnesium-rich chlorite occur in intergranular pores. Sparry, iron-rich dolomite or ankerite that fills pores in irregular millimeter-size patches, occupies up to 10% of the reservoir rock. Typical reservoir porosity ranges from 16 to 19 percent and permeability ranges from 60 to 700 md. By contrast non-reservoir delta-fringe sands typically have porosities of 6 to 12 percent and permeabilities of 1 to 20 md. Delta-fringe Tar Springs shales act as impermeable lateral and vertical seals, aiding in stratigraphic trapping.

  2. Sedimentological characterization of flood-tidal delta deposits in the Sego Sandstone, subsidence analysis in the Piceance Creek Basin, and uranium-lead geochronology (NW Colorado, USA)

    NASA Astrophysics Data System (ADS)

    York, Carly C.

    The Sego Sandstone located in western Colorado is a member of the Upper Cretaceous Mesaverde Group and is considered an analogue of the Canadian heavy oil sands. Deposition of the Sego Sandstone occurred during the Upper Campanian (~78 Ma) at the end of the Sevier Orogeny and the beginning of the Laramide Orogeny on the western edge of the Cretaceous Interior Seaway. Although regional studies have detailed time equivalent deposits in the Book Cliffs, UT, the tidally influenced and marginal marine lithofacies observed north of Rangely, CO are distinctly different from the dominately fluvial and tidally-influenced delta facies of Book Cliff outcrops to the southwest. This study characterized flood-tidal delta deposits within the Sego Sandstone, the subsidence history of the Upper Cretaceous sedimentary rocks within the present day Piceance Creek Basin in NW Colorado, and the detrital zircon signal and oldest depositional age of the Sego Sandstone. The goals of this study are to (i) identify relative controls on reservoir characteristics of marginal marine deposits, specifically in flood-tidal delta deposits; (ii) identify the possible mechanisms responsible for subsidence within the present day Piceance Creek Basin during the Late Cretaceous; and (iii) better constrain the provenance and maximum depositional age of the Sego Sandstone. In this study I compared grain size diameter, grain and cement composition, and the ratio of pore space/cement from thin sections collected in tidal, shoreface, and flood-tidal delta facies recognized along detailed measured stratigraphic sections. This analysis provides a detailed comparison between different depositional environments and resultant data showed that grain size diameter is different between tidal, shoreface, and flood-tidal delta facies. Identifying the subsidence mechanisms affecting the Piceance Creek Basin and sediment source of the Late Cretaceous sediments, on the other hand, is important for evaluation of controls

  3. Preservation of anomalously high porosity in deeply buried sandstones by grain-coating chlorite: Examples from the Norwegian Continental Shelf

    SciTech Connect

    Ehrenberg, S.N. )

    1993-07-01

    Five Lower to Middle Jurassic sandstone reservoirs from the Norwegian sector provide examples of deep porosity preservation caused by grain-coating, authigenic chlorite. Wide porosity variations in clean sandstones correlate with an abundance of grain-coating chlorite and consequent inhibition of quarts cementation. Maximum porosities tend to decrease with increasing depth but generally are 10-15% higher than would be predicted from regional trends of mean porosity vs. depth. It is proposed in this paper that the high chlorite content of the porous zones reflects syndepositional concentration of Fe-rich marine clays analogous to minerals of the modern verdine facies. Fe-clay mineralization would have been localized where Fe-rich river water was discharged into the sea. The syndepositional clays were transformed during burial diagenesis into grain coatings of radially oriented chlorite crystals. Petrographic relationships indicate that these coatings grew mainly before the beginning of quartz cementation and feldspar grain dissolution (probably within the first 2 km of burial) but after grain contacts had become adjusted by mechanical compaction. The Norwegian examples demonstrate that a wide range of nearshore marine sand-body types is susceptible to chlorite mineralization. The distribution of anomalous porosity and the proportion of the net sand affected depend upon sedimentary facies architecture and the pattern of discharge of Fe-rich river water during sand deposition. This phenomenon can be critically important for hydrocarbon exploration because it can provide good reservoir quality at depths far below the [open quotes]economic basement[close quotes] originally defined on the basis of sandstones lacking chlorite coatings. 58 refs., 25 figs., 1 tab.

  4. Preserving Native American petroglyphs on porous sandstone

    USGS Publications Warehouse

    Grisafe, D.A.

    1996-01-01

    A new method of chemical treatment is proposed to improve the durability of soft, porous sandstones onto which Native American petroglyphs have been carved. Cores of Dakota Sandstone from the Faris Cave site, located along the Smoky Hill River in Ellsworth County, Kansas, were treated with ethyl silicate dissolved in a lightweight ketone carrier, and some cores were subsequently treated with a combination of ethyl silicate and silane using the same solvent. Measurement of the resulting physical properties, when compared to untreated cores, indicate the treatments substantially increased the compressive strength and freeze-thaw resistance of the stone without discoloring the stone or completely sealing the pore system. The treatment increases the durability of the stone and provides a method for preserving the petroglyphs at the site. After treating test panels at the site, the petroglyphs were treated in like manner.

  5. Fractures and stresses in Bone Spring sandstones

    SciTech Connect

    Warpinski, N.R.; Sattler, A.R.; Lorenz, J.C.; Northrop, D.A.

    1992-06-01

    This project was a collaboration between Sandia National Laboratories and the Harvey E. Yates Company (Heyco), Roswell, NM, conducted under the auspices of Department of Energy's Oil Recovery Technology Partnership. The project applied Sandia perspectives on the effects of natural fractures, stress, and sedimentology for the stimulation and production of low permeability gas reservoirs to low permeability oil reservoirs, such as those typified by the Bone Spring sandstones of the Delaware Basin, southeast New Mexico. This report details the results and analyses obtained in 1990 from core, logs, stress, and other data taken from three additional development wells. An overall summary gives results from all five wells studied in this project in 1989--1990. Most of the results presented are believed to be new information for the Bone Spring sandstones.

  6. Ordovician conodonts and stratigraphy of the ST. Peter sandstone and glen wood shale, central United States

    USGS Publications Warehouse

    Witzke, B.J.; Metzger, R.A.

    2005-01-01

    The age of the St. Peter Sandstone in the central and northern Midcontinent has long been considered equivocal because of the general absence of biostratigraphically useful fossils. Conodonts recovered from the St. Peter Sandstone in Iowa, Minnesota, Nebraska, and Kansas for this study help place some age constraints on this renowned formation in its northern and western extent. Faunas from the lower St. Peter include Phragmodus flexuosus, Cahabagnathus sp., and Leptochirognathus sp., and a late Whiterockian (Chazyan) correlation is indicated. Juvenile or immature elements of P. flexuosus from these collections show morphologies trending toward P. cognitus and P. inflexus, and paedomorphic derivation of these latter species is proposed. Diverse assemblages of hyaline forms also occur in the St. Peter strata (Erismodus spp., Erraticodon sp., Curtognathus sp., Coleodus sp., Archeognathus sp., Stereoconus sp., others) along with various albid elements (Plectodina sp., Eoplacognathus sp., others). The overlying Glenwood Shale contains abundant conodonts dominated by Phragmodus cognitus, Erismodus sp., and Chirognathus duodactylus, and the fauna is interpreted as an early Mohawkian (Blackriveran) association. Certain thin shale units in the St. Peter-Glenwood succession represent condensed intervals, in part reflected by their exceptionally high conodont abundances. Some organic-rich phosphatic shale units in the lower St. Peter of western Iowa have produced equivalent yields of tens of thousands of conodonts per kilogram, and many Glenwood Shale samples yield thousands of conodonts per kilogram. Previous depositional models have proposed that the St. Peter is primarily a succession of littoral and nearshore facies forming a broadly diachronous transgressive sheet sand. However, broad-scale diachroneity cannot be demonstrated with available biostratigraphic control. The recognition of condensed marine shale units, phosphorites, ironstones, and pyritic hardgrounds in the

  7. Experimental research on seismoelectric effects in sandstone

    NASA Astrophysics Data System (ADS)

    Peng, Rong; Wei, Jian-Xing; Di, Bang-Rang; Ding, Pin-Bo; Liu, Zi-Chun

    2016-09-01

    The seismoelectric effects induced from the coupling of the seismic wave field and the electromagnetic field depend on the physical properties of the reservoir rocks. We built an experimental apparatus to measure the seismoelectric effects in saturated sandstone samples. We recorded the seismoelectric signals induced by P-waves and studied the attenuation of the seismoelectric signals induced at the sandstone interface. The analysis of the seismoelectric effects suggests that the minimization of the potential difference between the reference potential and the baseline potential of the seismoelectric disturbance area is critical to the accuracy of the seismoelectric measurements and greatly improves the detectability of the seismoelectric signals. The experimental results confirmed that the seismoelectric coupling of the seismic wave field and the electromagnetic field is induced when seismic wave propagating in a fluid-saturated porous medium. The amplitudes of the seismoelectric signals decrease linearly with increasing distance between the source and the interface, and decay exponentially with increasing distance between the receiver and the interface. The seismoelectric response of sandstone samples with different permeabilities suggests that the seismoelectric response is directly related to permeability, which should help obtaining the permeability of reservoirs in the future.

  8. Lower Permian fluvial cyclicity and stratigraphic evolution of the northern margin of Gondwanaland: Warchha Sandstone, Salt Range, Pakistan

    NASA Astrophysics Data System (ADS)

    Ghazi, Shahid; Mountney, Nigel P.; Sharif, Sadaf

    2015-06-01

    During the Lower Permian (Artinskian), fluvial conditions prevailed in what is now the Salt Range of northern Pakistan. Deposits of the Warchha Sandstone are characterised by a range of fluvial facies and architectural elements that together record both the proximal and distal parts of a meandering river system that drained the northern margin of Gondwanaland. Stratigraphic units are arranged into vertically stacked fining-upward cycles represented by thin accumulations of channel-lag deposits at their bases, and sandstone-dominated channel fill and thicker accumulations of overbank mudstone at their tops. Sedimentary cyclicity records fluvial system development on a variety of spatial and temporal scales. Overall, the Warchha Sandstone preserves a series of three to ten vertically stacked fining-upward cycles that form part of a larger-scale, third-order sequence that is itself bounded by regionally extensive and laterally correlatable unconformities that were generated in response to combined tectonic and eustatic changes. The sequence-stratigraphic architecture reflects regional palaeogeographic development of the Salt Range region. The small-scale fluvial cycles originated through autogenic mechanisms, predominantly as a result of repeated channel avulsion processes that occurred concurrently with on-going subsidence and the progressive generation of accommodation. Each erosively based fining-upward fluvial cycle is divided into three parts: a lower part of trough cross-bedded conglomerate and coarse sandstone; a middle part of tabular cross-bedded, ripple cross-laminated and horizontally laminated sandstone; and an upper part of predominantly horizontally laminated and massive mudstone. Overall, the Warchha Sandstone records the progradation of a wedge of non-marine strata into a previously shallow-marine depositional setting. The underlying marine Dandot Formation is terminated by a major unconformity that represents a type-I sequence boundary associated with

  9. Jonah field, sublette county, Wyoming: Gas production from overpressured Upper Cretaceous Lance sandstones of the Green River basin

    USGS Publications Warehouse

    Montgomery, S.L.; Robinson, J.W.

    1997-01-01

    Jonah field, located in the northwestern Green River basin, Wyoming, produces gas from overpressured fluvial channel sandstones of the Upper Cretaceous Lance Formation. Reservoirs exist in isolated and amalgamated channel facies 10-100 ft (3-30 m) thick and 150-4000 ft (45-1210 m) wide, deposited by meandering and braided streams. Compositional and paleocurrent studies indicate these streams flowed eastward and had their source area in highlands associated with the Wyoming-Idaho thrust belt to the west. Productive sandstones at Jonah have been divided into five pay intervals, only one of which (Jonah interval) displays continuity across most of the field. Porosities in clean, productive sandstones range from 8 to 12%, with core permeabilities of .01-0.9 md (millidarcys) and in-situ permeabilities as low as 3-20 ??d (microdarcys), as determined by pressure buildup analyses. Structurally, the field is bounded by faults that have partly controlled the level of overpressuring. This level is 2500 ft (758 m) higher at Jonah field than in surrounding parts of the basin, extending to the top part of the Lance Formation. The field was discovered in 1975, but only in the 1990s did the area become fully commercial, due to improvements in fracture stimulation techniques. Recent advances in this area have further increased recoverable reserves and serve as a potential example for future development of tight gas sands elsewhere in the Rocky Mountain region.

  10. Depositional history of Dakota Sandstone, Moxa Arch and vicinity, southwestern Wyoming - implications for early evolution of Cretaceous Foreland Basin

    SciTech Connect

    Ryer, T.A.; McClurg, J.J.; Muller, M.M.

    1987-05-01

    The Dakota Sandstone in the vicinity of the Moxa Arch is divided into upper and lower parts using an unconformity identified on the basis of petrographic evidence and facies relationships. The unconformity is believed to be of subaerial origin and came into being during a pronounced lowering of relative sea level during the late Albian. The lower Dakota consists predominantly of shoreline sandstone and offshore marine shale on the northern part of the Moxa Arch; it consists predominantly of fluvial strata on the southern part of the arch. Meander belts of the lower Dakota trend north-northeastward toward the west-northwest-trending shoreline of the Thermopolis Sea. The upper Dakota consists predominantly of strata deposited in low-energy, restricted marine paleoenvironments that came into being during gradual transgression of the Shell Creek/Mowery Sea. Barrier-island sandstones bodies are elongate toward the northeast, indicating that the shoreline trended in that direction. The reorientation of the shoreline from west-northwest-trending in the lower Dakota to northeast-trending in the upper Dakota is attributed to acceleration in the rate of subsidence in the foreland basin. The Shell Creek Sea advanced down the eastern side of the foreland basin, transgressing over lacustrine deposits that accumulated there during the low-stand of sea level. The Moxa Arch appears to have served as the eastern hinge of the foreland basin during the Dakota; only later, in the Late Cretaceous, did it assume the characteristics of a foreland welt.

  11. Matrix versus fracture permeability in a regional sandstone aquifer (Wajid sandstone, SW Saudi Arabia)

    NASA Astrophysics Data System (ADS)

    Al Ajmi, Hussain; Hinderer, Matthias; Rausch, Randolf; Hornung, Jens; Bassis, Alexander; Keller, Martin; Schüth, Christoph

    2014-06-01

    Sandstones are often characterized as fractured aquifers. We present a case study of the Wajid sandstone, which forms a regional aquifer system in SW Saudi Arabia, where matrix, fracture, and large-scale hydraulic conductivities are coincident. The measurements deal with different scales and methods and are based on porosity and permeability measurements in the laboratory, as well as pumping tests in the field. Porosities of the sandstone samples in general are high and range between less than 5 % and more than 45 %. Gas permeabilities for strongly cemented samples are < 1 mD, whereas most samples range in between 500 and 5,000 mD. There is only a weak anisotropy with preference of the horizontal x-, y-directions. Hydraulic conductivities of the matrix samples (5.5 · 10-6 m/s and 1.1 · 10-5 m/s for the Upper and Lower Wajid sandstone, respectively) were in the same order of magnitude compared to hydraulic conductivities derived from pumping tests (8.3 · 10-5 m/s and 2.2 · 10-5 m/s for the Upper and Lower Wajid sandstone, respectively).

  12. [FEATURES MORPHOLOGICAL PICTURE FACIES ORAL LIQUID IN PREGNANT].

    PubMed

    Iakovets, O V

    2015-01-01

    The features of morphological picture facies oral fluid of pregnant women with intact periodontal inflammatory diseases periodontal tissues. Results of the study were compared with the clinical picture. The features of morphological picture of the oral liquid with a healthy non-pregnant and periodontal inflammatory periodontal diseases in pregnant women. Revealed signs of inflammation markers in oral fluid facies in inflammatory processes in periodontal tissues.

  13. Sedimentary facies of alluvial fan deposits, Death Valley, California

    SciTech Connect

    Middleton, G.V. )

    1992-01-01

    Fans in Death Valley include both diamicts and bedded gravels. Seven facies may be recognized. The diamicts include: (1) matrix-rich, coarse wackestones; (2) thin, matrix-rich, fine wackestones, that may show grading; (3) matrix-poor, coarse packstones, transitional to wackestones. The bedded facies include: (4) weakly bedded, poorly sorted packstones or grainstones, that show patchy imbrication, and cut-and-fill structures; (5) packed, imbricated cobble lenses, generally interbedded in facies 4; (6) distinctly bedded gravels, that are better bedded, finer and better sorted, and show better imbrication than facies 4, but still do not show clear separation of sand and gravel beds; (7) backfill cross-bedded gravels. Sand beds are not seen in fan deposits. Sand is present in eolian deposits, as plane-laminated, back-eddy deposits in Death Valley Wash, and as laminated or rippled sand in the Amargosa River. The most remarkable features of the fan deposits are the very weak segregation of sand and gravel, and the complete absence of any lower flow-regime structures produced by ripples or dunes. During floods, the slope of fan and even large wash surfaces is steep enough to produce upper flow regimes. There are also very few trends in facies abundance down fans: most fans in Death Valley itself are not strongly dominated by debris flow deposits (diamicts). The facies characteristics of a given fan vary little from proximal to distal regions, but may differ strongly from the facies seen in adjacent fans. Ancient deposits that show clear segregation of gravel from cross-bedded sand beds, or strong proximal to distal facies transitions, must have been deposited in environments quite different from Death Valley.

  14. Fluvial architecture of the buntsandstein-facies redbeds in the middle to upper triassic (Ladinian-Norian) of the southeastern edge of the Iberian Meseta (Southern Spain)

    NASA Astrophysics Data System (ADS)

    Fernández, Juan; Dabrio, Cristino

    In the southeastern edge of the Iberian Meseta in Southern Spain, fluvial continental Buntsandstein-facies red beds of Middle to Upper Triassic (Ladinian — Norian) age unconformably overlie the folded and eroded Hercynian basement. The Betic Belts consist of an internal metamorphosed part and an external sedimentary zone containing the Triassic deposits, with the latter seam being in turn divided into the Prebetic Zone with continental to shallow marine facies and the Subbetic Zone with pelagic facies. The Buntsandstein-facies red bed series is vertically split into three main facies associations: alluvial fans and pebbly braided rivers (conglomerates and sandstones), low-sinuosity proximal and distal sandy braided rivers (sandstones and mudstones) and coastal evaporitic sabkha (mudstones, marls and gypsum). Alluvial-fan and pebbly braided river sediments occur at the base of the sequence and cover the palaeorelief of the pre-Triassic morphology. The inner fan zone is characterized by debris-flows or mud-flows, the mid fan zone is dominated by sheet floods, and the outer fan zone is governed by stream flood and stream flow passing into pebbly braided rivers in front of the fans. With transition from restricted alluvial fans to an open braidplain, the pebbly rivers soon evolve both vertically and horizontally into sandy stream networks consisting of channels and floodplains. The channel facies comprises sheet-type and ribbon-type sandstone layers. The sheets form complexes up to 15 m and more thickness due to amalgamation by multilateral coalescence and multivertical stacking of individual genetical units. In the lower part of the series, the number of channels is rather high suggesting a non-hierarchical channel pattern where high- and low-sinuosity rivers coexist. The middle portion reflects a smaller number of very large channels thus indicating an amelioration of the hierarchical pattern. The upper part consists of variegated sabkha plain mudstones and

  15. Palynostratigraphy and sedimentary facies of Middle Miocene fluvial deposits of the Amazonas Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Dino, Rodolfo; Soares, Emílio Alberto Amaral; Antonioli, Luzia; Riccomini, Claudio; Nogueira, Afonso César Rodrigues

    2012-03-01

    Palynostratigraphic and sedimentary facies analyses were made on sedimentary deposits from the left bank of the Solimões River, southwest of Manaus, State of Amazonas, Brazil. These provided the age-dating and subdivision of a post-Cretaceous stratigraphic succession in the Amazonas Basin. The Novo Remanso Formation is subdivided into upper and lower units, and delineated by discontinuous surfaces at its top and bottom. The formation consists primarily of sandstones and minor mudstones and conglomerates, reflecting fluvial channel, point bar and floodplain facies of a fluvial meandering paleosystem. Fairly well-preserved palynoflora was recovered from four palynologically productive samples collected in a local irregular concentration of gray clay deposits, rich in organic material and fossilized wood, at the top of the Novo Remanso Formation upper unit. The palynoflora is dominated by terrestrial spores and pollen grains, and is characterized by abundant angiosperm pollen grains ( Tricolpites, Grimsdalea, Perisyncolporites, Tricolporites and Malvacearumpollis). Trilete spores are almost as abundant as the angiosperm pollen, and are represented mainly by the genera Deltoidospora, Verrutriletes, and Hamulatisporis. Gymnosperm pollen is scarce. The presence of the index species Grimsdalea magnaclavata Germeraad et al. (1968) indicates that these deposits belong to the Middle Miocene homonymous palynozone (Lorente, 1986; Hoorn, 1993; Jaramillo et al., 2011). Sedimentological characteristics (poorly sorted, angular to sub-angular, fine to very-coarse quartz sands facies) are typical of the Novo Remanso Formation upper part. These are associated with a paleoflow to the NE-E and SE-E, and with an entirely lowland-derived palinofloristic content with no Andean ferns and gymnosperms representatives. All together, this suggests a cratonic origin for this Middle Miocene fluvial paleosystem, which was probably born in the Purus Arch eastern flank and areas surrounding the

  16. Control On Fluid Flow Properties In Sandstone: Interactions Between Diagenesis Processes And Fracture Corridors

    NASA Astrophysics Data System (ADS)

    Bossennec, Claire; Géraud, Yves; Moretti, Isabelle; Mattioni, Luca

    2016-04-01

    During the development of a fault zone, processes occur at different scales: secondary faults and fractures development in the damage zone while "diagenetic" processes, i.e: fluid rock interaction at the grains size scale, contribute to modify the matrix features. Spatial distribution of these processes is clearly controlled by microstructural transformations induced by fractured corridors and their location. Understanding flowing properties in the associated damage zone contributes to the better modeling of the fluid flow in faulted and fractured reservoirs which could be oil, gas or water bearing. The Lower Triassic Buntsandstein sandstones outcrop of Cleebourg is located in the Hochwald Horst affected by a major NNE-SSW striking fault, and the structure globally dips with 30° toward Rhenish Fault (Upper Rhine Graben main western border fault). The study of the outcrop aims to decipher the fluid-flow scheme and interactions between fracture network and diagenetic features distribution in the damage zone of a fault, located close to major faulted areas, through field and laboratories petrophysical measurements (permeability, thermic conductivity), and samples microstructural and diagenetical descriptions. The outcrop is structurally divided into a 14 meters thick fault core, surrounded by 5 meters thick transition zones, and damage zone of minimum thickness of 40 meters (total thickness unknown, due to the limits of the outcrop). Damage zone includes three fractured corridors, perpendicular to bedding and from 2 to 5 meters thick. Results presented here were acquired in 2 different layers with similar lithology but only on damage zone samples. In entire damage zone, porosity results and thin section description allow to distinguish two different facies: • Fa1 Intermediate porous (porosity of 12%) sandstone with major illite cement and clay content up to 20% (detrital and diagenetic); • Fa2 High porous (porosity >15%) sandstone with quartz feeding

  17. Hydrogeologic Framework of the Salt Basin, New Mexico and Texas

    NASA Astrophysics Data System (ADS)

    Ritchie, A. B.; Phillips, F. M.

    2010-12-01

    The Salt Basin is a closed drainage basin located in southeastern New Mexico (Otero, Chaves, and Eddy Counties), and northwestern Texas (Hudspeth, Culberson, Jeff Davis, and Presidio Counties), which can be divided into a northern and a southern system. Since the 1950s, extensive groundwater withdrawals have been associated with agricultural irrigation in the Dell City, Texas region, just south of the New Mexico-Texas border. Currently, there are three major applications over the appropriations of groundwater in the Salt Basin. Despite these factors, relatively little is known about the recharge rates and storage capacity of the basin, and the estimates that do exist are highly variable. The Salt Basin groundwater system was declared by the New Mexico State Engineer during 2002 in an attempt to regulate and control growing interest in the groundwater resources of the basin. In order to help guide long-term management strategies, a conceptual model of groundwater flow in the Salt Basin was developed by reconstructing the tectonic forcings that have affected the basin during its formation, and identifying the depositional environments that formed and the resultant distribution of facies. The tectonic history of the Salt Basin can be divided into four main periods: a) Pennsylvanian-to-Early Permian, b) Mid-to-Late Permian, c) Late Cretaceous, and d) Tertiary-to-Quaternary. Pennsylvanian-to-Permian structural features affected deposition throughout the Permian, resulting in three distinct hydrogeologic facies: basin, shelf-margin, and shelf. Permian shelf facies rocks form the primary aquifer within the northern Salt Basin, although minor aquifers occur in Cretaceous rocks and Tertiary-to-Quaternary alluvium. Subsequent tectonic activity during the Late Cretaceous resulted in the re-activation of many of the earlier structures. Tertiary-to-Quaternary Basin-and-Range extension produced the current physiographic form of the basin.

  18. Synkinematic quartz cementation in partially open fractures in sandstones

    NASA Astrophysics Data System (ADS)

    Ukar, Estibalitz; Laubach, Stephen E.; Fall, Andras; Eichhubl, Peter

    2014-05-01

    Faults and networks of naturally open fractures can provide open conduits for fluid flow, and may play a significant role in hydrocarbon recovery, hydrogeology, and CO2 sequestration. However, sandstone fracture systems are commonly infilled, at least to some degree, by quartz cement, which can stiffen and occlude fractures. Such cement deposits can systematically reduce the overall permeability enhancement due to open fractures (by reducing open fracture length) and result in permeability anisotropies. Thus, it is important to identify the factors that control the precipitation of quartz in fractures in order to identify potential fluid conduits under the present-day stress field. In many sandstones, quartz nucleates syntaxially on quartz grain or cement substrate of the fracture wall, and extends between fracture walls only locally, forming pillars or bridges. Scanning electron microscope cathodoluminescence (SEM-CL) images reveal that the core of these bridges are made up of bands of broken and resealed cement containing wall-parallel fluid inclusion planes. The fluid inclusion-rich core is usually surrounded by a layer of inclusion-poor clear quartz that comprises the lateral cement. Such crack-seal textures indicate that this phase was precipitating while the fractures were actively opening (synkinematic growth). Rapid quartz accumulation is generally believed to require temperatures of 80°C or more. Fluid inclusion thermometry and Raman spectroscopy of two-phase aqueous fluid-inclusions trapped in crack-seal bands may be used to track the P-T-X evolution of pore fluids during fracture opening and crack-seal cementation of quartz. Quartz cement bridges across opening mode fractures in the Cretaceous Travis Peak Formation of the tectonically quiescent East Texas Basin indicate individual fractures opened over a 48 m.y. time span at rates of 16-23 µm/m.y. Similarly, the Upper Cretaceous Mesaverde Group in the Piceance Basin, Colorado contains fractures that

  19. Sedimentary facies and depositional environments of early Mesozoic Newark Supergroup basins, eastern North America

    USGS Publications Warehouse

    Smoot, J.P.

    1991-01-01

    The early Mesozoic Newark Supergroup consists of continental sedimentary rocks and basalt flows that occupy a NE-trending belt of elongate basins exposed in eastern North America. The basins were filled over a period of 30-40 m.y. spanning the Late Triassic to Early Jurassic, prior to the opening of the north Atlantic Ocean. The sedimentary rocks are here divided into four principal lithofacies. The alluvial-fan facies includes deposits dominated by: (1) debris flows; (2) shallow braided streams; (3) deeper braided streams (with trough crossbeds); or (4) intense bioturbation or hyperconcentrated flows (tabular, unstratified muddy sandstone). The fluvial facies include deposits of: (1) shallow, ephemeral braided streams; (2) deeper, flashflooding, braided streams (with poor sorting and crossbeds); (3) perennial braided rivers; (4) meandering rivers; (5) meandering streams (with high suspended loads); (6) overbank areas or local flood-plain lakes; or (7) local streams and/or colluvium. The lacustrine facies includes deposits of: (1) deep perennial lakes; (2) shallow perennial lakes; (3) shallow ephemeral lakes; (4) playa dry mudflats; (5) salt-encrusted saline mudflats; or (6) vegetated mudflats. The lake margin clastic facies includes deposits of: (1) birdfoot deltas; (2) stacked Gilbert-type deltas; (3) sheet deltas; (4) wave-reworked alluvial fans; or (5) wave-sorted sand sheets. Coal deposits are present in the lake margin clastic and the lacustrine facies of Carnian age (Late Triassic) only in basins of south-central Virginia and North and South Carolina. Eolian deposits are known only from the basins in Nova Scotia and Connecticut. Evaporites (and their pseudomorphs) occur mainly in the northern basins as deposits of saline soils and less commonly of saline lakes, and some evaporite and alkaline minerals present in the Mesozoic rocks may be a result of later diagenesis. These relationships suggest climatic variations across paleolatitudes, more humid to the

  20. Build-and-fill sequences: How subtle paleotopography affects 3-D heterogeneity of potential reservoir facies

    USGS Publications Warehouse

    McKirahan, J.R.; Goldstein, R.H.; Franseen, E.K.

    2005-01-01

    This study analyzes the three-dimensional variability of a 20-meter-thick section of Pennsylvanian (Missourian) strata over a 600 km2 area of northeastern Kansas, USA. It hypothesizes that sea-level changes interact with subtle variations in paleotopography to influence the heterogeneity of potential reservoir systems in mixed carbonate-silidclastic systems, commonly produdng build-and-fill sequences. For this analysis, ten lithofacies were identified: (1) phylloid algal boundstone-packstone, (2) skeletal wackestone-packstone, (3) peloidal, skeletal packstone, (4) sandy, skeletal grainstone-packstone, (5) oolite grainstone-packstone, (6) Osagia-brachiopod packstone, (7) fossiliferous siltstone, (8) lenticular bedded-laminated siltstone and fine sandstone, (9) organic-rich mudstone and coal, and (10) massive mudstone. Each facies can be related to depositional environment and base-level changes to develop a sequence stratigraphy consisting of three sequence boundaries and two flooding surfaces. Within this framework, eighteen localities are used to develop a threedimensional framework of the stratigraphy and paleotopography. The studied strata illustrate the model of "build-and-fill". In this example, phylloid algal mounds produce initial relief, and many of the later carbonate and silidclastic deposits are focused into subtle paleotopographic lows, responding to factors related to energy, source, and accommodation, eventually filling the paleotopography. After initial buildup of the phylloid algal mounds, marine and nonmarine siliciclastics, with characteristics of both deltaic lobes and valley fills, were focused into low areas between mounds. After a sea-level rise, oolitic carbonates formed on highs and phylloid algal facies accumulated in lows. A shift in the source direction of siliciclastics resulted from flooding or filling of preexisting paleotopographic lows. Fine-grained silidclastics were concentrated in paleotopographic low areas and resulted in clay

  1. A shallow marine volcaniclastic facies model: an example from sedimentary rocks bounding the subaqueously welded Ordovician Garth Tuff, North Wales, U.K.

    NASA Astrophysics Data System (ADS)

    Fritz, William J.; Howells, Malcolm F.

    1991-11-01

    Volcaniclastic sedimentary rocks bounding the Ordovician Garth Tuff in North Wales were deposited in a shallow marine setting adjacent to a magmatic arc. The volcaniclastic sedimentary rocks are primarily of angular to euhedral quartz, angular euhedral feldspar, and volcanic rock fragments. These grains are of a pyroclastic origin, but have been reworked to various degrees. Sedimentary rock fragments, rounded quartz, muscovite, biotite, iron-rich chlorite and various clay minerals occur in lesser amounts. The sedimentary rocks can be divided into a proximal offshore to foreshore facies association (POFFA) and an offshore to lower shoreface facies association (OLSFA). The sand-dominated POFFA, exposed near Capel Curig, is characterized by large wave ripples, hummocky cross-stratification, co-sets of trough cross-beds, reactivation surfaces, plane beds, and graded turbidite layers in suspension-deposited mudstone. Water depths calculated from bedding plane exposure of large wave ripples and determined by the presence of hummocky cross-stratification and by facies association vary from a few meters to around 30 m (45-50 m theoretical maximum) in a 45 m-thick stratigraphic section beneath the tuff. Eight kilometers to the southeast, the Garth Tuff is bounded by a thick sequence of suspension-deposited laminated mudstone with thin graded beds of siltstone and fine-grained sandstone. This facies association (OLSFA) represents the introduction of material by distal turbidites and by pelagic sedimentation. The OLSFA was deposited in water depths well below storm wave base, possibly in excess of 200 m. No evidence of storm waves or surface-generated currents occur until over 40 m above the tuff. This study documents marine sedimentary rocks, deposited in water depths ranging from foreshore to offshore, as the bounding facies of the Garth Tuff. It is, thus, reasonable to conclude that the Garth Tuff was emplaced and welded in water depths greater than the thickness of the

  2. Putative domal microbial structures in fluvial siliciclastic facies of the Mesoproterozoic (1.09 Ga) Copper Harbor Conglomerate, Upper Peninsula of Michigan, USA.

    PubMed

    Wilmeth, Dylan T; Dornbos, Stephen Q; Isbell, John L; Czaja, Andrew D

    2014-01-01

    The Copper Harbor Conglomerate is a Mesoproterozoic (1.09 Ga) freshwater sedimentary sequence that outcrops in the Upper Peninsula of Michigan. The formation was deposited during infilling of the failed Midcontinent Rift and contains fluvial, lacustrine, and alluvial fan facies. This study describes and analyzes the formation of small domal structures preserved in fluvial sandstone facies within the lower portion of the formation. These domal structures range from millimeters to several centimeters in diameter and height, and are preserved in convex epirelief on fine-grained sandstone beds. The structures have a pustulose texture and a patchy distribution on bedding planes. Slabs containing the structures were collected in the field and analyzed in the laboratory through inspection of cut slabs, petrographic thin sections, X-radiographs, and RAMAN spectroscopy. Results of these analyses reveal that the domal structures often contain weak, wavy horizontal bedding and laminae, and lack any vertical structures. These results support a biogenic origin of the domal structures instead of through abiogenic processes such as loading, sand volcanoes, or adhesion warts. These structures are akin to what were traditionally labeled as 'sand stromatolites', but are now known as 'domal sand structures'. Along with previous descriptions of carbonate stromatolites, organic-rich paleosols, and microbial sand structures, our findings provide further evidence that mat-forming microbial communities thrived in the late Mesoproterozoic freshwater systems of the Midcontinent Rift.

  3. Fine-Grained Turbidites: Facies, Attributes and Process Implications

    NASA Astrophysics Data System (ADS)

    Stow, Dorrik; Omoniyi, Bayonle

    2016-04-01

    Within turbidite systems, fine-grained sediments are still the poor relation and sport several contrasting facies models linked to process of deposition. These are volumetrically the dominant facies in deepwater and, from a resource perspective, they form important marginal and tight reservoirs, and have great potential for unconventional shale gas, source rocks and seals. They are also significant hosts of metals and rare earth elements. Based on a large number of studies of modern, ancient and subsurface systems, including 1000s of metres of section logging, we define the principal genetic elements of fine-grained deepwater facies, present a new synthesis of facies models and their sedimentary attributes. The principal architectural elements include: non-channelised slope-aprons, channel-fill, channel levee and overbank, turbidite lobes, mass-transport deposits, contourite drifts, basin sheets and drapes. These comprise a variable intercalation of fine-grained facies - thin-bedded and very thin-bedded turbidites, contourites, hemipelagites and pelagites - and associated coarse-grained facies. Characteristic attributes used to discriminate between these different elements are: facies and facies associations; sand-shale ratio, sand and shale geometry and dimensions, sand connectivity; sediment texture and small-scale sedimentary structures; sediment fabric and microfabric; and small-scale vertical sequences of bed thickness. To some extent, we can relate facies and attribute characteristics to different depositional environments. We identify four distinct facies models: (a) silt-laminated mud turbidites, (b) siliciclastic mud turbidites, (c) carbonate mud turbidites, (d) disorganized silty-mud turbidites, and (e) hemiturbidites. Within the grainsize-velocity matrix turbidite plot, these all fall within the region of mean size < 0.063mm, maximum grainsize (one percentile) <0.2mm, and depositional velocity 0.1-0.5 m/s. Silt-laminated turbidites and many mud

  4. Resources of Texas Libraries.

    ERIC Educational Resources Information Center

    Holley, Edward G.; Hendricks, Donald D.

    This study of library resources was undertaken as a part of a statewide plan for higher education in Texas. The document includes descriptions of library facilities and resources at the University of Texas at Austin, other universities, and public and private junior and senior colleges. The public library network, health science libraries, law…

  5. Earth Observation - Texas Wildfire

    NASA Image and Video Library

    2011-06-19

    ISS028-E-008374 (21 June 2011) --- One of the Expedition 28 crew members aboard the International Space Station, flying at an altitude of approximately 235 statute miles, on June 21 spotted and photographed this image of one of the major Texas wildfires currently burning up massive acreage. This one is near Jasper and Lake Sam Rayburn in far east Texas.

  6. Earth Observation - Texas Wildfire

    NASA Image and Video Library

    2011-06-19

    ISS028-E-008373 (21 June 2011) --- One of the Expedition 28 crew members aboard the International Space Station, flying at an altitude of approximately 235 statute miles, on June 21 spotted and photographed this image of one of the major Texas wildfires currently burning up massive acreage. This one is near Jasper and Lake Sam Rayburn in far east Texas.

  7. Earth Observation - Texas Wildfire

    NASA Image and Video Library

    2011-06-19

    ISS028-E-008377 (21 June 2011) --- One of the Expedition 28 crew members aboard the International Space Station, flying at an altitude of approximately 235 statute miles, on June 21 spotted and photographed this image of one of the major Texas wildfires currently burning up massive acreage. This one is near Jasper and Lake Sam Rayburn in far east Texas.

  8. Fireball Over Texas

    NASA Image and Video Library

    Video of the fireball seen over Texas this morning (12/7/12); it was taken by a NASA camera located near Mayhill, New Mexico. It is very unusual for us to see a meteor all the way across Texas. The...

  9. Earthquake history of Texas

    USGS Publications Warehouse

    von Hake, C. A.

    1977-01-01

    Seventeen earthquakes, intensity V or greater, have centered in Texas since 1882, when the first shock was reported. The strongest earthquake, a maximum intensity VIII, was in western Texas in 1931 and was felt over 1 165 000 km 2. Three shocks in the Panhandle region in 1925, 1936, and 1943 were widely felt. 

  10. Migrant Programs in Texas.

    ERIC Educational Resources Information Center

    Carrasco, Frank, Ed.

    The purpose of this handbook is to provide information on migrant programs and services in the state of Texas. Data are gathered from 92 of the 254 counties in Texas. There is a profile for each county selected and for all migrant programs identified in each county. Descriptions of Title III-B migrant programs, the High School Equivalency program,…

  11. Facies comparison of autochthonous and allochthonous Permian and Triassic units, north-central Brooks Range, Alaska

    SciTech Connect

    Adams, K.E.

    1985-04-01

    Eight stratigraphic sections of Permian and Triassic rocks have been studied over a 30 km by 150 km area in the Endicott and Philip Smith Mountains of the central Brooks Range. Six of the sections are located on the Endicott Mountains allochthon, and the remaining two are parautochthonous columns in the Mount Doonerak area. The sections record a facies transition between the autochthonous Sadlerochit Group and Shublik Formation of the northeastern Brooks Range and the characteristically siliceous rocks of the allochthonous Siksikpuk and Otuk formations of the western Brooks Range. Laterally continuous and bioturbated beds of fine-grained sandstone, siltstone, and shale dominantly compose the Permian sequence, whereas the Triassic rocks consist of black shales, thin rhythmically bedded siliceous mudstones, and fossiliferous limestones. When the allochthonous sections are restored to a position south of the Mount Doonerak area, a general shallowing trend from southwest to northwest becomes evident within the reconstructed marine basin. To the south and west, the Permian sediments show a marked increase in silica content, with the occurrence of barite and a corresponding decrease in the thickness of the basal, coarser grained clastics. The Triassic formations also document an increase in silica and the presence of barite to the south and west, while becoming significantly sooty and phosphatic to the north and east. Ongoing petrographic and micropaleontologic studies of the field data will clarify these general paleogeographic relationships.

  12. Mechanical stratigraphy of deep-water sandstones: insights from a multisciplinary field and laboratory study

    NASA Astrophysics Data System (ADS)

    Agosta, Fabrizio; di Celma, Claudio; Tondi, Emanuele; Corradetti, Amerigo; Cantalamessa, Gino

    2010-05-01

    Turbidite sandstones found in deep-water fold-and-thrust belts are increasingly exploited as hydrocarbon reservoirs. Within these rocks, the fluid flow is profoundly affected by the complex interaction between primary sedimentological and stratigraphic attributes (i.e, facies, layering, reservoir quality, stacking patterns, bed connectivity and lateral extent) and fracture characteristics (i.e., length, spacing, distribution, orientation, connectivity). Unfortunately, most of these features are at, or below, the resolution of conventional seismic datasets and, for this reason, their identification and localization represent one of the fundamental challenges facing exploration, appraisal and production of the sandstone reservoirs. In this respect, whereas considerable effort has been afforded to a characterization of the sedimentological and stratigraphic aspects of sandstones, detailed analysis of fractures in this type of successions has received significantly less attention. In this work, we combine field and laboratory analyses to assess the possible mechanical control exerted by the rock properties (grain size, intergranualr porosity, and Young modulus), as well as the influence of bed thickness, on joint density in turbidite sandstones. Joints are mode-I fractures occurring parallel to the greatest principle stress axis, which solve opening displacement and do not show evidence of shearing and enhance the values of total porosity forming preferential hydraulic conduits for fluid flow. Within layered rocks, commonly, joints form perpendicular to bedding due to overburden or exhumation. The empirical relation between joint spacing and bed thickness, documented in the field by many authors, has been mechanically related to the stress perturbation taking place around joints during their formation. Furthermore, close correlations between joint density and rock properties have been already established. In this present contribution, we focus on the bed

  13. Controls on stratigraphic architecture in contemporaneous delta systems from the Eocene Roda Sandstone, Tremp-Graus Basin, northern Spain

    NASA Astrophysics Data System (ADS)

    Leren, Beate L. S.; Howell, John; Enge, Håvard; Martinius, Allard W.

    2010-07-01

    The Eocene Roda Sandstone of the Spanish Pyrenees is comprised of two coeval coarse-grained delta systems which share correlatable surfaces but show a markedly different internal facies architecture. The two deltas developed contemporaneously with the differences in internal architecture attributed to basin morphology and the role of two, distinct sediment sources, while the correlatability of the larger-scale packages indicates an external, allocyclic control. As such the Roda Sandstone provides the possibility to address the relative roles of different parameters known to interact and control stratal architecture. The Roda Sandstone crops out at the NE-margin of the Tremp-Graus Basin, a "piggyback" basin initiated in Palaeogene times in the foreland of the Southern Pyrenees. The study area (˜ 30 km 2) is composed of the well-understood and well-exposed parts of the Roda Sandstone cropping out along the Isabena Valley, and the less-worked and less-exposed outcrops to the north along Barranco de Ricans and Barranco de Codoñeras. Data for this study include a combination of conventional sedimentology data coupled with analyses of 3D Virtual Outcrop Models. Based on these methods 8 different facies associations have been distinguished. Their distribution suggests that the Roda Sandstone is composed of two different but coeval delta systems and their linked subenvironments; a Gilbert-type delta outcropping along Isabena Valley, and a shoal-water fan delta along Barranco de Ricans and Barranco de Codoñeras. Along the Isabena Valley the outcrops of the Gilbert-type deltaic system are composed of at least 6 distinct packages (Roda U-Z) characterized by texturally mature, delta-front sandstones separated by offshore mudstones. The stacked basinward-stepping architecture of the Roda U-Y units here represents a minimum of 3 major phases of SW-directed progradation, capped by hardground horizons formed during the subsequent flooding phases. Tidally-modified delta

  14. Hydrogeological exploitation through structural analysis and petrophysical proprieties of the Barremian sandstone-calcareous bar in Agadir-Essaouira basin (Morocco)

    NASA Astrophysics Data System (ADS)

    Yacoubi, Latifa Al; Amrouch, Khalid; Jaillard, Etienne; Geraud, Yves; Masrour, Moussa; Ougadire, Mohamed; Lkebir, Noura; Bouchaou, Lhoussaine

    2017-04-01

    The Barremian unit in Agadir Essaouira basin consists of a sandstone-calcareous bar alternated with clays. The thickness of this bar is about 30 meters and may consist the best reservoir in the lower Cretaceous units. The porosity and permeability of the sandstones are controlled by carbonate cementation. Several thin sections were studied in details in order to explore the texture and mineral contents. The results show that the sandy limestone and lithic sandstones facies have poor reservoir potential due to the limited fluid circulation. On the other hand, the sandstones are characterized by dolomite crystals replacing carbonates cement, which is confirmed by the petrophysical study. The measurements reveal that the primary permeability is about 1.8 10-4 mD to 1.3 mD in sandy-limestone and about 1.6 mD to 1.3 103 mD in sandstones, while the porosity is about 3.22% to 8.54 % in sandy-limestone and about 13.08% to 23.03 % in sandstones. Detailed fracture analyzes are measured within the Barremian bar in both North and South Atlasic folds. As a result, the fractures are similar between the two synclines, with a major set of N105-130 direction and minor set of N20-30 direction in the North and the South flanks of the South Atlasic fold respectively. The North Atlasic fold showed a major set of N80-100 direction and a minor set of N0-15 direction. The average intensity of fractures is about 11 fractures/m2. The results show that the Barremian unit is controlled by early sedimentlogical processes. The intense fracture network enables water to circulate within fractures which increases the porosity. Chemical water analyzes reveal that the groundwater is enriched on (Ca2+ + Mg2+) and SO42- due water/rock interactions.

  15. Late Neogene stratigraphy and tectonic control on facies evolution in the Laguna Salada Basin, northern Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Martín-Barajas, A.; Vázquez-Hernández, S.; Carreño, A. L.; Helenes, J.; Suárez-Vidal, F.; Alvarez-Rosales, J.

    2001-10-01

    The Laguna Salada Basin (LSB) in northeastern Baja California records late-Neogene marine incursions in the Salton Trough and progradation of the Colorado River delta. Early subsidence and subsequent tectonic erosion are related to evolution of the Sierra El Mayor detachment fault during late Miocene time (<12 Ma). The stratigraphy of uplifted blocks on the east-central margin of the Laguna Salada Basin and from three exploratory wells allows reconstruction of the main sedimentary and tectonic events. Marine mudstone and sandstone, and subordinate conglomerate of the Imperial Formation tectonically overlie metamorphic and granitic basement. Microfossils, lithology, and sedimentary structures in the Imperial Formation define Upper Miocene (<6 Ma) outer-shelf facies that grade up-section into inner-shelf and tide-dominated delta plain deposits of the ancient Colorado River. Lower Pliocene (˜4-2 Ma) reddish, sub-arkosic fluvial sandstone and siltstone of the Palm Spring Formation defines progradation of non-marine fluvio-deltaic deposits over the marine Imperial Formation. Continuous outcrops of the Palm Spring are less than 170-m thick, but correlative deposits are more than 570 m thick in the lower part of a 2400-m deep geothermal exploratory well on the eastern margin of LSB. Interfingering fluvial-sandstone deposits and prograding alluvial fanglomerates with coarse debris-flow and rock-avalanche deposits crudely mark the onset of vertical slip along the Laguna Salada fault and rapid uplift of Sierra Cucapa and Sierra El Mayor. Up to 2 km of Quaternary alluvial-fan and lacustrine deposits accumulated along the eastern margin of LSB, whereas lower subsidence rates produced a thinner sedimentary wedge over a ramp-like crystalline basement along the western margin. In early Pleistocene time (˜2-1 Ma), the Laguna Salada became progressively isolated from the Colorado River delta complex, and the Salton Trough by activity on the Elsinore and Laguna Salada fault zones.

  16. Vista from Curiosity Shows Crossbedded Martian Sandstone

    NASA Image and Video Library

    2015-09-11

    Large-scale crossbedding in the sandstone of this ridge on a lower slope of Mars' Mount Sharp is common in petrified sand dunes. The scene combines multiple images taken with both cameras of the Mast Camera (Mastcam) on Curiosity on Aug. 27, 2015, during the 1,087th Martian day, or sol of the rover's work on Mars. It spans from east, at left, to south-southwest. Figure 1 includes a scale bar of 200 centimeters (about 6.6 feet). Sets of bedding laminations lie at angles to each other. Such crossbedding is common in wind-deposited sandstone of the U.S. Southwest. An example from Utah is pictured at http://3dparks.wr.usgs.gov/zion/html2/3d153.html. The sandstone in the image from Mars is part of the Stimson unit on Mount Sharp. The color of the Mastcam mosaic has been approximately white-balanced to resemble how the scene would appear under daytime lighting conditions on Earth. The component images in the center and upper portion of the mosaic are from Mastcam's right-eye camera, which is equipped with a 100-millimeter-focal-length telephoto lens. Images used in the foreground and at far left and right were taken with Mastcam's left-eye camera, using a wider-angle, 34-millimeter lens. Malin Space Science Systems, San Diego, built and operates Curiosity's Mastcam. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, built the rover and manages the project for NASA's Science Mission Directorate, Washington. For more information about Curiosity, visit http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl . http://photojournal.jpl.nasa.gov/catalog/PIA19818

  17. Microfacies and depositional environment of the Word Formation (Permian) Glass Mountains, Texas

    SciTech Connect

    Rathjen, J.D. . Dept. of Geological Sciences)

    1993-02-01

    The Word Formation (Permian) crops out in the Glass Mountains of West Texas. The Word is composed of clastics in the southwest, carbonates in the northeast, and a transitional zone of alternating carbonates and clastics separating the two extreme facies. Sediment thickness ranges from 457 meters in the southwest to 91 meters in the northeast. Measured sections and petrographic data have identified six microfacies from the transitional and eastern facies of the Word. These are southwest to northeast: (1) Peloidal Packstones, (2) Bioclastic Wackestones/Packstones, (3) Whole Fossil Wackestones/Packstones, (4) Bioturbated Wackestones, (5) Fusulinid-Crinoid Packstones, and from the eastern facies, (6) Dolostones. Petrographic data indicate that a shallow water lagoonal environment existed in the southwest. This lagoonal environment grades into a more fossiliferous normal marine environment toward the northeast. In the northeast, a very shallow water shelf environment existed which was periodically subaerially exposed, dolomitizing the sediments.

  18. Understanding chemical and facies variability in the Murray Formation, Gale crater, from ChemCam data

    NASA Astrophysics Data System (ADS)

    Rivera-Hernandez, Frances; Mangold, Nicolas; Sumner, Dawn Y.; Nachon, Marion; Wiens, Roger C.; Maurice, Sylvestre; Forni, Olivier; Frydenvang, Jens; Newsom, Horton; Dehouck, Erwin; Payre, Valerie

    2017-04-01

    The primary goal of the Mars Science Laboratory (MSL) mission is to determine if habitable environments existed on Mars [1]. To evaluate the potential for habitability, reconstructing the transport and depositional history of the sedimentary rocks at Gale Crater relies on the accurate interpretation of changes in depositional facies. This study uses ChemCam data to identify and characterize chemical variations that may be due to grain size and possibly facies changes within the Murray formation, a fluvio-lacustrine unit in Gale Crater dominated by interbedded mudstones and fine-grained sandstones [1]. These analyses compliment current efforts by APXS and ChemCam in reconstructing a chemostratigraphic record for the Curiosity rover traverse [e.g.,2,3]. Textural analyses from images taken by the Mars Hand Lens Imager (MAHLI), and the ChemCam Remote Micro Imager (RMI), and ChemCam chemical data were used to exclude targets with resolvable diagenetic features. Remaining targets were analyzed for chemical heterogeneity using the Gini Index (G), where G=0 indicates no point-to-point chemical variation and G=1 for a completely heterogeneous target [4]. Sandstones with grains larger than the laser beam diameter ( 0.3-0.5 mm; medium sand) typically have G>0.25 [4]. Hence, heterogeneity in composition among closely spaced points on a single target may reflect variations in mineralogy among individual sand grains or concentrations of grains. In contrast, homogeneous rocks may have homogeneous grain compositions or only contain grains smaller than sand. Thus, even when the presence of sand grains cannot be demonstrated from images, their presence can be inferred using the Gini Index. Preliminary analyses from sols 1400-1500 suggest that the abundances of FeOT, SiO2, Al2O3, and TiO2 do not vary significantly in individual rock targets (G<0.1) or between targets. In contrast, CaO, MgO, K2O, and Na2O vary more from target to target (G>0.1). Most variations between targets are

  19. Poncho field - Cretaceous J sandstone stratigraphic traps - Denver basin, Colorado

    SciTech Connect

    Ethridge, F.G.; Ziegler, J.R.

    1983-08-01

    Distributary channel and delta destructional sandstones of Early Cretaceous age are important reservoirs for stratigraphic traps in the J sandstone at Poncho field, Adams and Arapahoe Counties, Colorado. Cores and logs from the field area reveal a lowermost, nonproductive, northeast-trending delta front sandstoe (J-3); a middle complex of southeast- and east-trending, productive distributary channel sandstones (J-2) that grade into tightly cemented delta fringe marine sediments to the southeast and northeast; and an upper, northeast trending, productive delta destructional sandstone (J-1). Vertical and lateral sequences of sedimentary structures, textures, trace fossil assemblages, and geometry and trend of sandstone bodies suggest that these units were part of a wave-dominated delta complex that prograded to the east and southeast from the area of Lonetree field. Thin section and SEM analyses reveal that the principal cements in both reservoir sandstones are quartz overgrowths, kaolinite, and chlorite, and that the bulk of the porosity is secondary and related to dissolution of carbonate cement and feldspar grains. Porosities and permeabilities are most variable and lowest in the nonproductive delta front sandstones, averaging 15% and 7 md; variable and intermediate in the productive distributary channel sandstones, averaging 16% and 28 md; and most uniform and highest in the overlying delta destructional sandstones, averaging 21% and 88 md.

  20. An evaluation of alternative chemical classifications of sandstones

    USGS Publications Warehouse

    Lindsey, D.A.

    1999-01-01

    Chemical classification of sandstone is worth attempting because modern analytical methods are producing extensive data sets on rock composition. Previous compilations and statistical studies have demonstrated the application of chemical data to problems in sandstone petrology, but classification has been largely ignored. Chemical data has value for classification, but the limitations of using chemical data for classification must be identified. Consideration of the processes of sandstone formation permits formulation of classification guidelines and systems for classification. Alternative systems for chemical classification can be then evaluated for their power to identify major types of sandstones and to facilitate genetic interpretation.

  1. Discolored Fracture Zones in Martian Sandstone

    NASA Image and Video Library

    2015-12-17

    This view from NASA's Curiosity Mars rover shows an example of discoloration closely linked to fractures in the Stimson formation sandstone on lower Mount Sharp. The pattern is evident along two perpendicular fractures. Curiosity's Navigation Camera (Navcam) acquired the component images of this mosaic on Aug. 23, 2015, during the 1.083rd Martian day, or sol, of the mission. The location is along the rover's path between "Marias Pass" and "Bridger Basin." In this region, the rover has found fracture zones to be associated with rock compositions enriched in silica, relative to surrounding bedrock. http://photojournal.jpl.nasa.gov/catalog/PIA20268

  2. Radiogenic heat production in sedimentary rocks of the Gulf of Mexico Basin, south Texas

    USGS Publications Warehouse

    McKenna, T.E.; Sharp, J.M.

    1998-01-01

    Radiogenic heat production within the sedimentary section of the Gulf of Mexico basin is a significant source of heat. Radiogenic heat should be included in thermal models of this basin (and perhaps other sedimentary basins). We calculate that radiogenic heat may contribute up to 26% of the overall surface heat-flow density for an area in south Texas. Based on measurements of the radioactive decay rate of ??-particles, potassium concentration, and bulk density, we calculate radiogenic heat production for Stuart City (Lower Cretaceous) limestones, Wilcox (Eocene) sandstones and mudrocks, and Frio (Oligocene) sandstones and mudrocks from south Texas. Heat production rates range from a low of 0.07 ?? 0.01 ??W/m3 in clean Stuart City limestones to 2.21 ?? 0.24??W/m3 in Frio mudrocks. Mean heat production rates for Wilcox sandstones, Frio sandstones, Wilcox mudrocks, and Frio mudrocks are 0.88, 1.19, 1.50, and 1.72 ??W/m3, respectively. In general, the mudrocks produce about 30-40% more heat than stratigraphically equivalent sandstones. Frio rocks produce about 15% more heat than Wilcox rocks per unit volume of clastic rock (sandstone/mudrock). A one-dimensional heat-conduction model indicates that this radiogenic heat source has a significant effect on subsurface temperatures. If a thermal model were calibrated to observed temperatures by optimizing basal heat-flow density and ignoring sediment heat production, the extrapolated present-day temperature of a deeply buried source rock would be overestimated.Radiogenic heat production within the sedimentary section of the Gulf of Mexico basin is a significant source of heat. Radiogenic heat should be included in thermal models of this basin (and perhaps other sedimentary basins). We calculate that radiogenic heat may contribute up to 26% of the overall surface heat-flow density for an area in south Texas. Based on measurements of the radioactive decay rate of ??-particles, potassium concentration, and bulk density, we

  3. Petrology and palaeoenvironmental significance of authigenic iron-rich clays, carbonates and apatite in the Claiborne Group, Middle Eocene, NE Texas

    NASA Astrophysics Data System (ADS)

    Huggett, J. M.; Gale, A. S.; McCarty, D.

    2010-07-01

    The Claiborne Group (Eocene) in North East Texas consists of clayey sandstones and mudrocks, both with variable proportions of dark green to brown clay pellets deposited in a marginal to open marine setting on the Gulf Coast margin. The composition of concretionary carbonate and clay pellets, from 5 localities, has been investigated using a wide variety of analytical techniques. Our palaeontological, sedimentological, C/S and stable isotope data support an interpretation of marginal marine facies with limited freshwater input, for the Claiborne Group. Dark green (mature) pellets are predominantly associated with transgressive, bioturbated, marine sediments. From the Weches Formation through to the youngest Crockett Formation there is a trend from pellets composed mostly of dark green serpentine-rich mixed layer clay to those of mostly brown (immature) nontronite-rich mixed layer clay. The serpentine is intermediate between odinite and berthierine and may have been originally odinite that has undergone partial transformation to berthierine. Pellet maturity apparently corresponds with the degree of winnowing and sedimentation rate. It does not appear to correspond with global temperature fluctuations, though the serpentine-rich rather than glauconite-rich composition may do. Siderite cement, mostly in the form of concretions, post-dates the iron-rich clay pellets and pre-dates calcite cement. Carbonate and apatite concretions show a wide range of mineral cement textures, reflecting variation in sedimentary environment and early diagenetic processes. Based on water temperatures derived from verneriacardia bivalves a precipitation temperature of 20 °C is assumed for the concretionary siderite. Using this temperature we surmise that the siderite precipitated from marine pore waters with intermittent meteoric water mixing.

  4. Lower Eocene carbonate facies of Egypt: paleogeographic and tectonic implications

    SciTech Connect

    Garrison, R.E.

    1983-03-01

    The northern Arabo-Nubian craton witnessed a major Late Cretaceous-early Tertiary marine transgression that culminated in the deposition of widespread shelf-sea carbonates during Early Eocene (Ypresian) time. Outer shelf facies characterize exposures in central Egypt (Assiut, Luxor, Kharga), and are composed primarily of rhythmically interbedded chalk and micritic limestone with minor intercalated marine hardgrounds. To the south (Kurkur-Dungul), these fine-grained lithologies give way to inner shelf foraminiferal wackestones and grainstones, typical Tethyan Nummulitic facies. Missing in southern Egypt is the restricted dolomitic evaporitic facies predicted by the Irwin model and observed in the lower Eocene of the Sirte basin to the west and the Arabian Platform to the east. Comparing the areal distribution of these lower Eocene carbonates to coeval facies developed across the remained of northern Africa and Arabia reveals the presence of a broad marine embayment which extended through central and eastern Egypt into northern Sudan during Ypresian time. The widespread subsidence that resulted in the development of this features may have been an effect of regional crustal attenuation preceding the rifting of the Red Sea. Concomitant with this regional subsidence were localized uplift and extensional block faulting in the vicinity of the incipient Red Sea rift (the Safaga-Quseir coastal plain). Here, lower Eocene carbonate facies are indicative of shallow water platforms developed on horst blocks, and deeper water, turbidite-fed basins in intervening grabens.

  5. Anisotropy of permeability in faulted porous sandstones

    NASA Astrophysics Data System (ADS)

    Farrell, N. J. C.; Healy, D.; Taylor, C. W.

    2014-06-01

    Studies of fault rock permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of porous sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host rock porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (σ1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted porous sandstone by compaction and reorganisation of grains through shearing and cataclasis.

  6. Compaction of Norphlet sandstones, Rankin County, Mississippi

    SciTech Connect

    McBride, E.F.

    1987-09-01

    Fabric and porosity changes resulting from compaction were studied in sandstones from three cores sampled at depths between 15,900 and 22,500 ft. Point counts of 30 thin sections indicate that 0.4% of the rock volume was lost by ductile grain deformation and 3% by pressure solution at both grain contacts and at widely spaced stylolites. Pre-cement porosities of eolian sandstone range from 27 to 35% (mean = 29%), indicating that a total of from 10 to 18% porosity (mean = 16%) was lost by compaction (assuming 45% initial porosity). The difference between the total porosity loss and the sum of the other two processes is assumed to be the porosity lost by grain rearrangement (mean = 12.6%). The amount of pressure solution at grain contacts for each well is independent of depth, temperature, and amount of both quartz cement and total cement. Stylolites transect both grains and cements, which indicates they formed late in the diagenetic sequence. Silica released by pressure solution at quartz grain contacts could not be the sole source and was probably not even the major source of quartz cement in the formation, because cementation by quartz preceded the episode of strong pressure solution. In addition, the volume of silica released by pressure solution appears to have been inadequate to provide the volume of quartz cement present.

  7. Is there a basin-centered gas accumulation in Cotton Valley Group Sandstones, Gulf Coast Basin, U.S.A.?

    USGS Publications Warehouse

    Bartberger, Charles E.; Dyman, Thaddeus S.; Condon, Steven M.

    2002-01-01

    The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, is reevaluating the resource potential of selected domestic basin-centered gas accumulations. Basin-centered gas accumulations are characterized by presence of gas in extensive low-permeability (tight) reservoirs in which conventional seals and trapping mechanisms are absent, abnormally high or low reservoir pressures exist, and gas-water contacts are absent. In 1995, the USGS assessed one basin-centered gas play and two conventional plays within the trend of Jurassic and Cretaceous Cotton Valley Group fl uvial-deltaic and barrierisland/ strandplain sandstones across the onshore northern Gulf of Mexico Basin. Detailed evaluation of geologic and production data provides new insights into these Cotton Valley plays. Two Cotton Valley sandstone trends are identifi ed based on reservoir properties and gas-production characteristics. Transgressive blanket sandstones across northern Louisiana have relatively high porosity and permeability and do not require fracture stimulation to produce gas at commercial rates. South of this trend, and extending westward into eastern Texas, massive sandstones of the Cotton Valley trend exhibit low porosity and permeability and require fracture stimulation. The high permeability of Cotton Valley blanket sandstones is not conducive to the presence of basin-centered gas, but lowpermeability massive sandstones provide the type of reservoir in which basin-centered gas accumulations commonly occur. Data on source rocks, including burial and thermal history, are consistent with the interpretation of potential basincentered gas within Cotton Valley sandstones. However, pressure gradients throughout most of the blanket- and massivesandstone trends are normal or nearly normal, which is not characteristic of basin-centered gas accumulations. The presence of gas-water contacts in at least seven fi elds across the blanket-sandstone trend together with relatively

  8. Delineation of geological facies from poorly differentiated data

    SciTech Connect

    Wohlberg, Brendt; Tartakovsky, Daniel

    2008-01-01

    The ability to delineate geologic facies and to estima.te their properties from sparse data is essential for modeling physical and biochemical processes occurring in the 'ubsurface. If such data are poorly differentiated, this challcnrring task is complicated further by the absence of a clear distinction between different hydrofacies even at locations where data. are available. vVe consider three alt mative approaches for analysis of poorly differentiated data: a k-means clU!:iterinrr algorithm, an expectation-maximization algorithm, and a minimum-variance algorithm. Two distinct synthetically generated geological settings are used to r:tnalyze the ability of these algorithmti to as ign accurately the membership of such data in a given geologic facies. On average, the minimum-variance algorithm provides a more robust p rformance than its two counterparts and when combined with a nearest-neighbor algorithm, it also yields the most accurate reconstruction of the boundaries between the facies.

  9. A locally adaptive kernel regression method for facies delineation

    NASA Astrophysics Data System (ADS)

    Fernàndez-Garcia, D.; Barahona-Palomo, M.; Henri, C. V.; Sanchez-Vila, X.

    2015-12-01

    Facies delineation is defined as the separation of geological units with distinct intrinsic characteristics (grain size, hydraulic conductivity, mineralogical composition). A major challenge in this area stems from the fact that only a few scattered pieces of hydrogeological information are available to delineate geological facies. Several methods to delineate facies are available in the literature, ranging from those based only on existing hard data, to those including secondary data or external knowledge about sedimentological patterns. This paper describes a methodology to use kernel regression methods as an effective tool for facies delineation. The method uses both the spatial and the actual sampled values to produce, for each individual hard data point, a locally adaptive steering kernel function, self-adjusting the principal directions of the local anisotropic kernels to the direction of highest local spatial correlation. The method is shown to outperform the nearest neighbor classification method in a number of synthetic aquifers whenever the available number of hard data is small and randomly distributed in space. In the case of exhaustive sampling, the steering kernel regression method converges to the true solution. Simulations ran in a suite of synthetic examples are used to explore the selection of kernel parameters in typical field settings. It is shown that, in practice, a rule of thumb can be used to obtain suboptimal results. The performance of the method is demonstrated to significantly improve when external information regarding facies proportions is incorporated. Remarkably, the method allows for a reasonable reconstruction of the facies connectivity patterns, shown in terms of breakthrough curves performance.

  10. Madison Group (Mississippian) reservoir facies of Williston Basin, North Dakota

    SciTech Connect

    Lindsay, R.F.

    1985-02-01

    Twenty-seven oil fields producing from the Mission Canyon Limestone and Charles Formation (Madison Group) were studied: 1) along the eastern basin margin (Bluell, Sherwood, Mohall, Glenburn, Haas, and Chola fields), 2) northeast of Nesson anticline (Foothills, North Black Slough, South Black Slough, Rival, Lignite, and Flaxton), 3) along Nesson anticline (North Tioga, Tioga, Beaver Lodge, Capa, Hoffland, Charlson, Hawkeye, Blue Buttes, Antelope, and Clear Creek), and 4) south of the basin center (Lone Butte, Little Knife, Big Stick, Fryburg, and Medora). Mission Canyon reservoirs along the eastern margin are in several shoaling-upward carbonate to anhydrite cycles of pisolitic packstone or grainstone buildups. South of the basin center, only a single shoaling-upward sequence is present, with dolomitized, mostly restructed-marine skeletal wackstone to pelletal wackstone or packstone reservoir facies. Nesson anticline, between these 2 areas, contains a single shoaling-upward sequence without an anhydrite cap. In northern Nesson anticline, Mission Canyon reservoir facies are oolitic-pisolitic, intraclastic wackestone or grainstone buildups or open-marine skeletal packstone or grainstone. Both limestones and dolostones are productive in southern Nesson anticline. Limestone reservoir facies are transitional, open to restricted-marine slightly intraclastic, skeletal wackestone or packstone facies. Dolostone reservoir facies are restricted-marine mudstone to skeletal mudstone and pelletal wackestone or packstone. Northeast of the Nesson anticline, production is from oolitic to pisolitic packstone or grainstone buildups in the Rival subinterval and from restricted-marine, dolomitized spiculitic mudstone in the Midale subinterval (base of Charles Formation). In the northern Nesson anticline, Rival reservoir facies are offshore open to restricted-marine, skeletal, intraclastic, pelletal wackestone and/or packstones.

  11. Scope and construction of a gas and oil atlas series of the Gulf of Mexico: Examples from Texas offshore lower Miocene plays

    SciTech Connect

    Seni, S.J.; Desselle, B.A.; Standen, A.

    1994-12-31

    An atlas series about the offshore northern Gulf of Mexico will group gas and oil reservoirs into subregional plays and will display reservoir data on a computerized geographical information system. The atlas series will provide critically compiled reservoir engineering data to help the private sector explore and develop hydrocarbons and to help the public sector analyze the hydrocarbon endowment in this basin. In this report, we cover aspects of the play-analysis procedure and provide specific examples of lower Miocene plays from the upper Texas coast and Federal Outer Continental Shelf (OCS). Play analysis emphasizes using broad classes of structural style, depositional style and environments, and defining attributes to group reservoirs into plays. To date, we have identified 4 Oligocene and 25 Miocene plays in Texas State offshore waters and 115 plays in the Federal OCS. Texas State offshore plays are gas prone (cumulative production 3.7 TcF) and are preferentially trapped in rollover anticlines. Miocene plays include submarine-fan Lenticulina sandstones; progradational Dicorbis b., Siphonina d., Marginulina a., and Lenticulina sandstones; transgressive sandstones associated with a barrier-bar system in the Matagorda Area; and transgressive Amphistegina B sandstones. Particularly productive gas-prone plays are progradational Sihonina d. deltas in the High Island Area and progradational Marginulia a. shelf and deltaic sandstones in the Matagorda Island and Brazos Areas.

  12. Texas' forests, 2008

    Treesearch

    James W. Bentley; Consuelo Brandeis; Jason A. Cooper; Christopher M. Oswalt; Sonja N. Oswalt; KaDonna Randolph

    2014-01-01

    This bulletin describes forest resources of the State of Texas at the time of the 2008 forest inventory. This bulletin addresses forest area, volume, growth, removals, mortality, forest health, timber product output, and the economy of the forest sector.

  13. More CBE in Texas

    ERIC Educational Resources Information Center

    Sandoz, Ellis

    1977-01-01

    New accreditation regulations in Texas require competency-based education programs for all districts. All districts must be accredited to receive state aid, which makes up 85 cents of every dollar spent locally. (Author/IRT)

  14. Sylvatic trichinellosis in Texas.

    PubMed

    Pence, D B; La Rosa, G; Mancini Barbieri, F; Amati, M; Casulli, A; Pozio, E

    2001-06-01

    There are no published reports of domestic or sylvatic trichinellosis in Texas. The aim of the present survey was to determine the presence of Trichinella species in selected representative species of potential wildlife reservoirs in southern Texas. In 1998-99, tongues of 211 wild mammals were collected in southern Texas: 154 coyotes (Canis latrans), three bobcats (Lynx rufus), 32 racoons (Procyon lotor), 13 opossum (Didelphis marsupialis), four ocelots (Leopardus pardalis) and five wild boars (Sus scrofa). Presence of Trichinella sp. larvae was investigated by artificial digestion and larvae of positive samples were identified at the species level by a multiple-polymerase chain reaction analysis. Nine (5.8%) coyotes had trichinellosis; in the muscles of seven of these coyotes, the larvae were identified as Trichinella murrelli. This is the first report of sylvatic trichinellosis in Texas.

  15. Diagenesis of the Almond sandstone in the Washakie Basin

    SciTech Connect

    Yin, Peigui; Liu, Jie; Surdam, C.R. . Dept. of Geology and Geophysics)

    1992-01-01

    The marginal marine and nonmarine Almond sandstones are mostly sublitharenite, litharenite, and lithic arkose. The sandstones are fine-to very-fine-grained, and are well-sorted. The framework composition, authigenic minerals, and porosity and permeability distributions in the Almond sandstones are different below and above 8,000 feet, resulting in a variation in hydrocarbon reservoir types. The shallow conventional reservoirs are permeable, producing both liquid oil and gas, whereas the deep gas-bearing sandstones are very tight and overpressured. Porosity of the shallow Almond sandstones have been significantly enhanced by dissolution of the feldspar grains and lithic fragments. Quartz overgrowth cement and authigenic clay rims have occluded most of the intergranular pores, as well as the previously leached pores. The Almond sandstones have been buried deeper than their present depths. The sandstones in each part of the Washakie Basin have experienced different uplift and subsidence. Reconstruction of the burial history and diagenetic modeling are essential steps for understanding the diagenetic evolution of the Almond sandstones.

  16. Paluxy of the Central Basin-East Texas

    SciTech Connect

    Presley, M.W. )

    1993-09-01

    The Paluxy Formation (Lower Cretaceous) has been a consistent sandstone exploration objective in the central East Texas basin, occurring at moderate depths on the order of 5000-8000 ft with oil in reservoirs with good permeability and porosity and reserves in the range of 200,000 to 500,000 bbl per well. Since the 1940s, the pace of Paluxy field discovery has been steady, generally a new field or two every one or two years, and there is every reason to believe that there is continued potential for the Paluxy in the future. The central part of the East Texas basin, in Smith County and adjacent areas, has complex structure with numerous salt domes and intervening sediment wedges (turtles) that formed during movement of the salt. Paluxy oil and gas in this area occurs mainly in combination structural-stratigraphic traps along normal faults that cut turtles. Major exploration trends in the central basin include (1) the Lindale turtle with a number of widely spaced fields, generally with only a few wells but with relatively good per-well reserves, (2) the Tyler turtle with the largest fields and some of the most prolific Paluxy production in the central basin, (3) the Flint and Irene turtles with relatively thin sandstones and modest production, (4) the Lane Chapel turtle with some exciting new Paluxy discoveries, and (5) the rim areas of salt domes.

  17. Provenance of sandstones in the Golconda terrane, north central Nevada

    SciTech Connect

    Jones, E.A. )

    1991-02-01

    The upper Paleozoic Golconda terrane of north-central Nevada is a composite of several structurally bounded subterranes made of clastic, volcanic, and carbonate rocks. The clastic rocks provide important clues for the interpretation of the provenance and paleogeographic settings of the different lithologic assemblages found in these subterranes. Two petrographically distinct sandstones are identified in the Golconda terrane in the Osgood Mountains and the Hot springs Range of north-central Nevada. The sandstone of the Mississippian Farrel Canyon Formation, part of the Dry Hills subterrane, is characterized by quartzose and sedimentary and lithic-rich clasts with a small feldspar component. in contrast, the sandstone of the Permian Poverty Peak (II) subterrane is a silty quartzarenite with no lithic component, and a very limited feldspar component. The sandstone of the Farrel Canyon Formation is similar to nonvolcanic sandstones reported from elsewhere in the Golconda terrane. Modal data reflect a provenance of a recycled orogen and permit the interpretation that it could have been derived from the antler orogen as has been proposed for other sandstones of the golconda terrane. The sandstone of the Poverty Peak (II) subterrane is more mature than any of the other sandstones in either the Golconda terrane, the Antler overlap sequence, or the Antler foreland basin sequence. Modal data put the Poverty Peak (II) sandstone in the continental block provenance category. The distinct extrabasinal provenances represented in these different sandstones support the idea that the Golconda basin was made up of complex paleogeographic settings, which included multiple sources of extrabasinal sediment.

  18. Recognition and significance of parasequences and parasequence sets in Leonard carbonate reservoirs, west Texas

    SciTech Connect

    Ruppel, S.C. )

    1991-03-01

    Although hydrocarbon production from reservoirs of Leonardian age is sizable (cumulative production from the Leonardian on the Central Basin Platform (CBP) alone totals 1.4 billion bbls), recovery efficiencies from these restricted, shallow-water platform carbonate deposits are among the lowest in west Texas, averaging only about 19%. Detailed examination of the Leonard section in the Dollarhide and Monahans fields on the CBP indicates that poor recovery from these reservoirs is a function of extreme vertical heterogeneity produced by high-order oscillations of relative sea level. The Leonard sequence is composed of thin (1- to 2-m thick), upward-shallowing parasequences, each of which is marked at its base by a prominent marine flooding surface. Parasequences are, in turn, packaged into 15- to 20-m parasequence set defined by variations in parasequence facies stacking patterns. Reservoir porosity is typically preferentially developed in very thin (less than 1 m) zones of grain-rich subtidal facies within parasequences, although porosity may also be encountered in capping tidal-flat deposits. Because these facies display distinct pore and permeability characteristics, with subtidal facies usually exhibiting the highest permeabilities, development of accurate reservoir models for simulation and exploitation depends on the ability to distinguish and map these deposits. Recognition and correlation of parasequences and parasequence stacking patterns in parasequence sets provide a powerful tool for more accurate mapping of facies and attendant porosity development and facilitate development of improved models necessary for efficient exploitation of these highly heterogeneous reservoirs.

  19. Grampian high-pressure-granulite-facies metamorphism of the Slishwood Division, NW Ireland and its enigmatic eclogite-facies precursor

    NASA Astrophysics Data System (ADS)

    Daly, J. S.; Flowerdew, M. J.; Whitehouse, M. J.

    2012-04-01

    The Slishwood Division of NW Ireland is located along the SW margin of the Grampian belt, whose metamorphism and deformation is generally attributed to the collision of outboard magmatic arcs with the Laurentian continental margin during the c. 470 Ma Grampian Orogeny. The unusual metamorphic history of the Slishwood Division (with eclogite-facies and later high-pressure-granulite-facies assemblages) is a unique feature of the Grampian belt and has long been regarded as evidence for pre-Caledonian tectonism, possibly of Grenvillian age. Detrital zircon U-Pb dating of Slishwood Division metasediments shows that they were deposited after c. 926 Ma, ruling out a Grenville event. A maximum age for the eclogite-facies event is provided by a U-Pb zircon age of 596 ± 6 Ma for a suite of metabasite intrusives, which exhibit varying degrees of decompression from eclogite- to high pressure granulite-facies or amphibolite-facies assemblages accompanied by the development of migmatitic leucosomes. Zircons in these leucosomes yield U-Pb zircon ages of c. 470 Ma identical to metamorphic zircons in a relatively dry partially decompressed eclogite. Following polyphase deformation, migmatitic leucosomes in metasediments crystallized under high pressure granulite-facies conditions during sinistral transtension. Dating these leucosomes has been challenging because the majority of zircons within them are inherited and generally only thin (< 15 μm) euhedral magmatic zircon overgrowths are present. Careful targeting with the ion microprobe yields U-Pb ages of c. 470 Ma, consistent with a U-Pb zircon age of c. 470 Ma from a cross-cutting granite pegmatite. In addition the high pressure granulite facies mineral fabrics are cut by tonalite bodies also dated at 470 Ma (ref. 1). Based on these results, we interpret the Slishwood Division as a Neoproterozoic metasedimentary sequence deposited after c. 926 Ma on what became a microcontinental fragment that detached from Laurentia during the

  20. Sequence stratigraphic framework of the Cretaceous Gallup and Tocito sandstones, San Juan basin, New Mexico

    SciTech Connect

    Valasek, D.W. )

    1991-03-01

    The Gallup (Turonian) and Tocito (Coniacian) sandstones are hydrocarbon reservoirs in the San Juan basin, northwestern New Mexico. The Gallup is a regressive shoreface system capped by Dilco Member coastal plain deposits. The Tocito is a transgressive system of valley-fill, estuary, and shelf deposits. All of the units were deposited in a ramp setting. The Gallup is comprised of seaward-stepping (10-20 km) genetic units. Each genetic unit is also comprised of smaller scale (1.5-3 km) parasequences. Both scales are separated by flooding surfaces. Each genetic unit has an independent fluvial feeder system. The most well-developed, widespread, and amalgamated fluvial system correlates to the downward shift of facies basinward at the top of the shoreface. The base of the amalgamated fluvial, downward shifted facies and the valley fills is interpreted to be a sequence boundary. The Tocito fills the incised valleys, lies on the shoreface deposits, and is capped by the maximum flooding surface. Near the shoreface pinch out, the transgressive surface is amalgamated to the sequence boundary surface. These estuary/shelf deposits are the primary hydrocarbon reservoir. Landward, the transgressive surface lies on coastal plain deposits and stratigraphically climbs. The transgression was interrupted by a progradational event consisting of ebb and flood tidal delta deposits of the Borrego Pass Member. These genetic units form a landward-stepping geometry. Availability of outcrop exposures, well logs, and seismic data makes the Gallup/Tocito sequence an excellent example of the development of new exploration scenarios in well-exploited hydrocarbon reservoirs using sequence stratigraphy.

  1. Depositional and diagenetic variability within the Cambrian Mount Simon Sandstone: Implications for carbon dioxide sequestration

    USGS Publications Warehouse

    Bowen, B.B.; Ochoa, R.I.; Wilkens, N.D.; Brophy, J.; Lovell, T.R.; Fischietto, N.; Medina, C.R.; Rupp, J.A.

    2011-01-01

    The Cambrian Mount Simon Sandstone is the major target reservoir for ongoing geologic carbon dioxide (CO2) sequestration demonstrations throughout the midwest United States. The potential CO2 reservoir capacity, reactivity, and ultimate fate of injected CO2 depend on textural and compositional properties determined by depositional and diagenetic histories that vary vertically and laterally across the formation. Effective and efficient prediction and use of the available pore space requires detailed knowledge of the depositional and diagenetic textures and mineralogy, how these variables control the petrophysical character of the reservoir, and how they vary spatially. Here, we summarize the reservoir characteristics of the Mount Simon Sandstone based on examination of geophysical logs, cores, cuttings, and analysis of more than 150 thin sections. These samples represent different parts of the formation and depth ranges of more than 9000 ft (>2743 m) across the Illinois Basin and surrounding areas. This work demonstrates that overall reservoir quality and, specifically, porosity do not exhibit a simple relationship with depth, but vary both laterally and with depth because of changes in the primary depositional facies, framework composition (i.e., feldspar concentration), and diverse diagenetic modifications. Diagenetic processes that have been significant in modifying the reservoir include formation of iron oxide grain coatings, chemical compaction, feldspar precipitation and dissolution, multiple generations of quartz overgrowth cementation, clay mineral precipitation, and iron oxide cementation. These variables provide important inputs for calculating CO2 capacity potential, modeling reactivity, and are also an important baseline for comparisons after CO2 injection. Copyright ??2011. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  2. Attenuation of Landfill Leachate In Unsaturated Sandstone

    NASA Astrophysics Data System (ADS)

    Butler, A. P.; Brook, C.; Godley, A.; Lewin, K.; Young, C. P.

    Landfill leachate emanating from old "dilute and disperse" sites represents a potential (and in many cases actual) threat to the integrity of groundwater. Indeed, this concern has been included in EU legislation (80/86/EEC), where key contaminants (e.g. ammonia, various toxic organic compounds and heavy metals) are explicitly highlighted in terms of their impact on groundwater. In the UK, whilst there are a substantial number of unlined landfills sited on major aquifers, many of these are in locations where there is a substantial unsaturated zone. Thus, there exists the opportunity for the modification and attenuation of contaminants prior to it encountering the water table. An understanding of likely changes in leachate content and concentrations at such sites will enable a more comprehensive assessment of the potential risks and liabilities posed by such sites to be evaluated. The Burntstump landfill, situated 8 km north of Nottingham (UK), is sited on an outcrop of Sherwood sandstone. The fine friable sand has been quarried since the 1960s and the excavated volume used to store municipal waste. Filling at the site commenced in the mid 1970s and originally was unlined. In 1978 the first of what was to become a series of boreholes was installed within an area of roughly 5 m radius over one of the original waste cells. Cores of the waste and underlying sandstone were extracted and analysed for a range of physical and chemical parameters. The most recent set of analyses were obtained in 2000. The series of investigations therefore provide an important record of leachate migration and modification through the unsaturated zone for over twenty years. The progression of the leachate front is clearly delineated by the chloride concentration profile with an average velocity of around 1.6 m.yr-1. Combining this value with an average (and reasonably uniform) measured moisture content of about 7% gives a mean inter-granular specific discharge of 110 mm.yr-1. An interesting

  3. Marginal erg facies: A trial approach toward a descriptive classification

    SciTech Connect

    Caputo, M.V. ); Langford, R.P. )

    1991-03-01

    During the late 1970s and early 1980s, sedimentologists began recognizing the margins of eolian sand seas as separate, components which differed from interior sand seas in geometry, extent, and facies. Stratigraphers have now observed these differences in eolian rocks. Erg margins may be grouped in five ways: (1) by associations with extradunal environments-coastal plain, lacustrine, periglacial, marine (tidal flat, coastal sabkha, beach, and lagoon), and arid alluvial (alluvial fan, fluvial, playa, inland sabkha); (2) by allocyclic controls-eustasy, plate tectonism, and climate; (3) by autocyclic controls-local tectonism, topography, vegetation, hydrology, structure, sediment source and supply, and wind regime; (4) by geographic position-upwind, downwind, and along-wind margins; and (5) by sedimentary facies-texture and architecture. In contrast with erg interiors, erg margins are characterized by smaller, less complex dune-forms related to thinner sand accumulation; elementary dune architecture; more vegetation and bioturbation; high occurrence of sand sheet, zibar, and serir facies; expansive, low-relief interdunes with widely distributed dunes; and a greater proportion of interbedded extradunal deposits. Some of the published studies on ancient eolian systems have identified erg margin facies that have been influences by marine and arid alluvial processes. Few reports have described lacustrine-eolian and periglacial-eolian interactions. This study is an attempt to organize known features of modern and ancient erg margins into a scheme based on erg margin controls.

  4. Facies analysis of a Devonian carbonate shoreline system (northern Italy)

    NASA Astrophysics Data System (ADS)

    Galli, Gianni

    1986-01-01

    The upper part of a back-reef carbonate, regressive sequence of the Cima Ombladet (Devonian, Carnic Alps, Italy) has been investigated. According to textures, sedimentary structures, faunal content and bedding types, it has been subdivided into eight main facies, which represent three main environments deposited within a high-energy shoreline system: (1) a shoreface (open lagoon, brachiopod bar and intramicrudite facies); (2) a lower foreshore (pond, ridge, bioclast shoal and intraclast shoal facies); and (3) an upper foreshore consisting of well-sorted sands with cryptalgal laminae. Three main shallowing-upward sequences have been recognised within the complicated facies mosaic, which is a peculiar feature of the sequence: (1) a shoreface bar sequence formed within the open lagoon and was longshore and tidal current-dominated; (2) a storm bar sequence; and (3) a beach sequence formed within the foreshore. Storms, other than normal shoreline processes, played a significant role in controlling sand accumulation and geometry in the foreshore. In particular the beach was built by a stepwise lateral assemblage of sand bodies of different composition and originated from the reworking of open lagoonal bars and of the lagoonward terminations of the reef-flat environments, occurring as linear ridges.

  5. Predicted seafloor facies of Central Santa Monica Bay, California

    USGS Publications Warehouse

    Dartnell, Peter; Gardner, James V.

    2004-01-01

    Summary -- Mapping surficial seafloor facies (sand, silt, muddy sand, rock, etc.) should be the first step in marine geological studies and is crucial when modeling sediment processes, pollution transport, deciphering tectonics, and defining benthic habitats. This report outlines an empirical technique that predicts the distribution of seafloor facies for a large area offshore Los Angeles, CA using high-resolution bathymetry and co-registered, calibrated backscatter from multibeam echosounders (MBES) correlated to ground-truth sediment samples. The technique uses a series of procedures that involve supervised classification and a hierarchical decision tree classification that are now available in advanced image-analysis software packages. Derivative variance images of both bathymetry and acoustic backscatter are calculated from the MBES data and then used in a hierarchical decision-tree framework to classify the MBES data into areas of rock, gravelly muddy sand, muddy sand, and mud. A quantitative accuracy assessment on the classification results is performed using ground-truth sediment samples. The predicted facies map is also ground-truthed using seafloor photographs and high-resolution sub-bottom seismic-reflection profiles. This Open-File Report contains the predicted seafloor facies map as a georeferenced TIFF image along with the multibeam bathymetry and acoustic backscatter data used in the study as well as an explanation of the empirical classification process.

  6. Contractional deformation of porous sandstone: Insights from the Aztec Sandstone, SE Nevada, USA

    NASA Astrophysics Data System (ADS)

    Fossen, Haakon; Zuluaga, Luisa F.; Ballas, Gregory; Soliva, Roger; Rotevatn, Atle

    2015-05-01

    Contractional deformation of highly porous sandstones is poorly explored, as compared to extensional deformation of such sedimentary rocks. In this work we explore the highly porous Aztec Sandstone in the footwall to the Muddy Mountain thrust in SE Nevada, which contains several types of deformation bands in the Buffington tectonic window: 1) Distributed centimeter-thick shear-enhanced compaction bands (SECBs) and 2) rare pure compaction bands (PCBs) in the most porous parts of the sandstone, cut by 3) thin cataclastic shear-dominated bands (CSBs) with local slip surfaces. Geometric and kinematic analysis of the SECBs, the PCBs and most of the CSBs shows that they formed during ∼E-W (∼100) shortening, consistent with thrusting related to the Cretaceous to early Paleogene Sevier orogeny of the North American Cordilleran thrust system. Based on stress path modeling, we suggest that the compactional bands (PCBs and SECBs) formed during contraction at relatively shallow burial depths, before or at early stages of emplacement of the Muddy Mountains thrust sheet. The younger cataclastic shear bands (CSBs, category 3), also related to E-W Sevier thrusting, are thinner and show larger shear offsets and thus more intense cataclasis, consistent with the initiation of cataclastic shear bands in somewhat less porous materials. Observations made in this work support earlier suggestions that contraction lead to more distributed band populations than what is commonly found in the extensional regime, and that shear-enhanced compaction bands are widespread only where porosity (and permeability) is high.

  7. Wettability Behavior of Crude Oil-Silica Nanofluids-Sandstone Systems

    NASA Astrophysics Data System (ADS)

    Bai, Lingyun; Li, Chunyan; Pales, Ashley; Huibers, Britta; Ladner, David; Daigle, Hugh; Darnault, Christophe

    2016-04-01

    Mobilizing and recovering crude oils from geological formations is critical for the management and exploitation of petroleum reservoirs. Nanoparticles, with their unique physico-chemical properties can increase the efficiency of enhanced oil recovery (EOR) by decreasing interfacial tension (IFT) between the oil and aqueous phase systems, and altering rock wettability. Our research examines the potential use of nanoparticles as a means of EOR by studying the influence of silicon oxide (SIO2) nanoparticles on the wettability and interfacial tension of different crude oil-silica nanofluids-sandstone systems. We designed nanofluid treatments to manipulate changes in wettability of Berea and Boise sandstones simulating petroleum reservoir. Experiments were performed to measure the IFT and wettability involving different concentrations of nanoparticles with and without the addition of surfactant to determine which nanofluids produced the most favorable wettability changes for optimal EOR with light crude oil (e.g., West Texas, API: 40), medium crude oil (Prudhoe Bay, API: 28), and heavy crude oil (e.g., Lloydminster, API: 20). We investigated the addition of Tween 20 nonionic surfactant to the nanoparticle dispersions - made from SiO2 nanoparticles - that allows the optimum mobility in porous media through optimization of interfacial tension (IFT) and contact angle, and conducted tests. Batch studies were conducted to measure the IFT and wettability of the nanofluids of different range of nanoparticle concentrations (0-0.1 wt. %) in different reservoir conditions, i.e. brine and brine-surfactant systems made with 5% brine and 2CMC of Tween 20 nonionic surfactants. The dynamic behavior of IFT was monitored using a pendant drop method. Five percent brine-nanoparticle systems containing 0.001 and 0.01 wt.% of nanoparticles resulted in a significant decrease of IFT for light and medium crude oils, while the highest decrease of IFT for heavy crude oil was observed with 0.1 wt

  8. Chemostratigraphic and sedimentologic evolution of Wajid Group (Wajid Sandstone): An outcrop analog study from the Cambrian to Permian, SW Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Yassin, Mohamed A.; Abdullatif, Osman M.

    2017-02-01

    The Paleozoic age succession in Saudi Arabia represents one of the most prolific petroleum producing systems in the Arabian Peninsula. This succession is also considered important for unconventional tight gas and shale gas reservoirs. The Wajid Group (Wajid Sandstone) in SW Saudi Arabia consists of four formations, namely, Dibsiyah (Lower and Upper), Sanamah, Khusayyayn and Juwayl from bottom to top. This study investigates the major oxides, trace and rare earth elements for the Wajid Group formations in southwestern Saudi Arabia. We characterize and compare the sandstone types, provenance, tectonic setting, and climate. Moreover, we applied the chemostratigraphic technique for stratigraphic differentiation. Concentrations of certain elements indicate that Wajid Group was deposited in a passive continental margin. The geochemical analysis reveals that Wajid Group sediments were likely derived from the upper and bulk continental crust and mafic igneous provenance. The elemental geochemical data has been applied in this study to improve the stratigraphic subdivision and correlation. Using selected elements, geochemical vertical profiles, binary, and ternary diagrams allow clearly distinguishing between Wajid Group formations. Thus supports the established formation boundaries that constructed using lithostratigraphy and sedimentology. The geochemical elements variation between formations can be related to differences in rock-forming minerals, facies change, climate, and provenance. The results of this study may help in constraining and correlating complex facies strata and can be used as a guide for stratigraphic correlations in the subsurface within the Wajid basin and other equivalent stratigraphic successions within Saudi Arabia.

  9. Provenance, sedimentology, and tectonic setting of ancient sandstones and conglomerates in a Continental rift basin: Espanola basin, Rio Grande rift, New Mexico

    SciTech Connect

    Cavazza, W.

    1988-02-01

    The Miocene fill of the Espanola basin half-graben is composed of two lithosomes with different provenance, paleocurrents, sandstone and conglomerate petrology, and sedimentary facies. Lithosome A has westward paleocurrents, basement-derived detrital composition, and represents sedimentation in a braid plain-sand flat-ephemeral lake system. Lithosome B has south-southwest-directed paleocurrents, a large volcaniclastic and sedimentary clastic detrital component, and represents a perennial fluvial system. Despite being derived from the unfaulted side of the Espanola half-graben, both lithosomes display upward-fining megasequences (100-400 m thick), comparable to similar megasequences derived from tectonically active basin margins. Thus, vertical arrangement of sedimentary deposits along the unfaulted margin of an asymmetrical rift basin can be determined by tectonism along the opposite, deeper margin. Continental rifts are ideal settings for detailed provenance studies. Variety of lithologies in the sediment source area (basement, sedimentary cover, and volcanic strata) provides petrologic tracers to delineate the sediment paleodispersal system. For the Miocene fill of the Espanola basin, integration of petrologic (sandstone point-counting, conglomerate clast-counting) and sedimentologic (paleocurrent and facies analyses) techniques resulted in identification of two genetically significant rock bodies not corresponding to previously established lithostratigraphic units.

  10. Sedimentary facies and evolution of large sandbody of the upper part of Huagang Formation in Xihu Sag, East China Sea Basin, China

    NASA Astrophysics Data System (ADS)

    Zhao, Shuai; Chen, Lin

    2017-04-01

    Xihu sag is one of the largest subprime unit of the east China sea basin. In recent years, with the discovery of some large-scale gas fields in the Huanggang Formation of Xihu Sag, the sedimentary facies and gas exploration of Huanggang Formation have become a hotspot of many domestic and overseas petroleum geologists study. This research mainly focused on the upper part of Huagang Formation which was composed by a set of large scale sandbodies in Xihu sag. Based on the application of sequence stratigraphy, sedimentology, and seismic sedimentology, this paper has studied the sedimentary facies and evolution of the upper part of Huagang Formation in Xihu Sag. The geophysical technologies, including seismic attributes, constrained sparse pulse inversion and post-stack geostatistical inversion, are also used to characterize the sandbodies' development features and spatial distribution of the upper part of Huagang Formation. Our results show that braided river is the main facies of the upper part in the Huagang Formation and The Huanggang Formation primary can be divided into lowstand systems tract (LST) and transgressive systems tract (TST). The upstream of the braided river is characterized by thick sandstone and narrow channel. The sandbody displays a better lateral continuity and the channel become wider from upstream to downstream. As the erosion of the incised channel weakened, the sandstone thickness tends to be thinner. Conglomerates can also be occasionally observed at the bottom of thick superimposed sandbodies. On both sides of the braided river, thin sandstone layers are developed. There are also visible of lateral migration of the sandbodies of the downstream. Lithology profiles also illustrate that the sandbodies display poor lateral continuity on the both sides of the braided river .Sedimentary evolution analysis showing that the braided channels are mainly developed in the LST of Lower Huagang Formation from the NNE axial to basin. During TST, the

  11. The Texas Twin Project.

    PubMed

    Harden, K Paige; Tucker-Drob, Elliot M; Tackett, Jennifer L

    2013-02-01

    Socioeconomic position, racial/ethnic minority status, and other characteristics of the macro-environment may be important moderators of genetic influence on a wide array of psychosocial outcomes. Designed to maximize representation of low socioeconomic status families and racial/ethnic minorities, the Texas Twin Project is an ongoing study of school-age twins (preschool through 12th grade) enrolled in public schools in the Austin, Texas and Houston, Texas metropolitan areas. School rosters are used to identify twin families from a target population with sizable populations of African American (18%), Hispanic/Latino (48%), and non-Hispanic White (27%) children and adolescents, over half of whom meet US guidelines for classification as economically disadvantaged. Initial efforts have focused on a large-scale, family-based survey study involving both parent and child reports of personality, psychopathology, physical health, academic interests, parent-child relationships, and aspects of the home environment. In addition, the Texas Twin Project is the basis for an in-laboratory study of adolescent decision-making, delinquency, and substance use. Future directions include geographic expansion of the sample to the entire state of Texas (with a population of over 25 million) and genotyping of participating twins.

  12. Linkage between fluid-rock-interactions and facial, petrographical, and geochemical properties of Buntsandstein aquifer sandstones of the Thuringian Basin, Central Germany

    NASA Astrophysics Data System (ADS)

    Hilse, U.; Beyer, D.; Kunkel, C.; Aehnelt, M.; Pudlo, D.; Voigt, T.; Gaupp, R.

    2012-04-01

    This study is part of a collaborative research project examining the basin wide movement of fluids in the subsurface (INFLUINS - integrated fluid dynamics in sediment basins). The Lower Triassic Buntsandstein is a major aquifer in Thuringia and adjacent areas in central Germany. The sediments exhibit an overall trend of base level and associated environmental changes. In the Lower Buntsandstein, deposition started with sediments indicating a playa-like setting. The Middle Buntsandstein consists of sediments of wide floodplains with very shallow rivers and eolian reworking in the lower part, and of deeper, long-ranged braided to meandering river systems in the upper part. Outcrop samples and core material were used for investigations and following discussion. For understanding fluid-rock-interactions in these sediments it is important to investigate the linkage between facies, rock composition, and mineral surfaces exposed to the pore space, as well as bulk rock and mineral chemistry. Compared to the clay rich lacustrine sediments of the Lower Buntsandstein the more porous fluvial and eolian sandstones of the Middle Buntsandstein represent better pathways for fluid migration in the present and past. The lacustrine and fluvial sandstones are mostly arkoses and subarkoses, whereas the eolian sandstones are often characterized by quartzarenitic composition. Facies variations and associated compositional differences are reflected in the geochemical composition of the rocks determined by ICP-MS/OES and XRF measurements. Sandstones of the Lower Buntsandstein are characterized by high contents of e.g. Al, Na, K, Fe, and Li, caused by the enrichment of clays and feldspars in the lacustrine sediments. Due to their higher compositional maturity, the fluvial (and eolian) sediments of the Middle Buntsandstein exhibit an increase of stable minerals towards the top, which is also reflected in geochemical data (increasing Si by decreasing Al, Na, K). By scanning electron

  13. Facies composition and scaling relationships of extensional faults in carbonates

    NASA Astrophysics Data System (ADS)

    Bastesen, Eivind; Braathen, Alvar

    2010-05-01

    Fault seal evaluations in carbonates are challenged by limited input data. Our analysis of 100 extensional faults in shallow-buried layered carbonate rocks aims to improve forecasting of fault core characteristics in these rocks. We have analyzed the spatial distribution of fault core elements described using a Fault Facies classification scheme; a method specifically developed for 3D fault description and quantification, with application in reservoir modelling. In modelling, the fault envelope is populated with fault facies originating from the host rock, the properties of which (e.g. dimensions, geometry, internal structure, petrophysical properties, and spatial distribution of structural elements) are defined by outcrop data. Empirical data sets were collected from outcrops of extensional faults in fine grained, micro-porosity carbonates from western Sinai (Egypt), Central Spitsbergen (Arctic Norway), and Central Oman (Adam Foothills) which all have experienced maximum burial of 2-3 kilometres and exhibit displacements ranging from 4 centimetres to 400 meters. Key observations include fault core thickness, intrinsic composition and geometry. The studied fault cores display several distinct fault facies and facies associations. Based on geometry, fault cores can be categorised as distributed or localized. Each can be further sub-divided according to the presence of shale smear, carbonate fault rocks and cement/secondary calcite layers. Fault core thickness in carbonate rocks may be controlled by several mechanisms: (1) Mechanical breakdown: Irregularities such as breached relays and asperities are broken down by progressive faulting and fracturing to eventually form a thicker fault rock layer. (2) Layer shearing: Accumulations of shale smear along the fault core. (3) Diagenesis; pressure solution, karstification and precipitation of secondary calcite in the core. Observed fault core thicknesses scatter over three orders of magnitude, with a D/T range of 1:1 to 1

  14. Depositional facies mosaics and their time lines in Lower Ordovician carbonates of central Appalachians

    SciTech Connect

    Nguyen, C.T.; Goldhammer, R.K.; Hardie, L.A.

    1985-02-01

    A comparative sedimentology and facies stratigraphy study of the Lower Ordovician carbonate of the central Appalachians (Beekmantown Group and equivalents) has been carried out. Our approach used subfacies (rock record of subenvironments) as the basin units of section measurement. The authors differentiated related sets of subfacies into larger facies units (rock record of environments). Facies were then correlated from section to section using fossils and lithostratigraphy to make a 3-dimensional facies mosaic. Within this mosaic, time lines were constructed using onlap-offlap tongues and cyclic sequences. These time lines cut across facies boundaries. Using this approach, the authors have established that the lower 600 m of the Lower Ordovician carbonate sequence is made up of 4 main facies: (1) cyclic laminite facies composed of a package of shoaling-upward shelf lagoon-peritidal cycles, (2) thin-bedded grainstone facies deposited in a shelf lagoon, (3) Renalcis bioherm facies recording a shelf lagoon patch-reef environment, and (4) Epiphyton bioherm facies recording a shelf-edge reef system. The distribution of these facies along time lines across the strike of the central Appalachians is markedly zoned. Epiphyton bioherm facies dominate the eastern margin while cyclic laminite facies dominate the western margin, with thin-bedded grainstone and Renalcis bioherm facies making up the central belt. This zonation of facies is a typical shallow carbonate shelf system with fringing reefs along the eastern, seaward margin and tidal flats along the western, landward margin. Vertical distribution of these facies across strike records 3 major sea level changes during deposition of the lower 600 m of this extensive Lower Ordovician carbonate shelf.

  15. Shallow marine sedimentary facies in the earliest Triassic (Griesbachian) Cordilleran miogeocline, U.S.A.

    NASA Astrophysics Data System (ADS)

    Paull, Rachel K.; Paull, Richard A.

    1994-11-01

    Permian history in the Cordilleran miogeocline, U.S.A., ended with an erosional interval of 1 to 22 million years. Previous studies of this event focused on unrepresented time, faunal extinction, regional truncation, or physical evidence in local areas. Another way to view this unconformity is to examine the nature of shallow marine sediments deposited on the erosional surface during the earliest Triassic (Griesbachian) transgression. As part of this study, the rate of the initial Mesozoic flood was estimated by determining the extent of the oldest Triassic conodont biozone within the study area. The calculated rate of transgression over 194,000 km 2 occupied by this biozone, within the 270,000 km 2 depositional area of the earliest Triassic Dinwoody Formation, is orders of magnitude greater than those suggested for eustatic sea-level change related to glaciation or plate tectonic processes. The rapidity of transgression, paucity of reworked material at the base of the Triassic, a general lack of local relief, and nearly conformable relations of Permian and Triassic rocks throughout the region suggest that the Triassic sea advanced across a featureless plain. The earliest Triassic sediments described in this study are restricted to the basal 2 m of the Dinwoody Formation. The generalized geographic distribution of facies within the depositional basin follows: evaporites are restricted to the northeast, Lingula-bearing dolomite characterizes the north-central, sandstone is locally present in the northwest and central areas, the southern part is dominated by shaly-bedded siltstone with some thin limestone interbeds, and calcareous, silty shale is present in the west toward the basin center. The similarity of basalmost Triassic depositional environments to those of the earlier Permian documents tectonic rejuvenation of a previous paleogeographic regime that strongly controlled Early Triassic sedimentation.

  16. A two scale analysis of tight sandstones

    NASA Astrophysics Data System (ADS)

    Adler, P. M.; Davy, C. A.; Song, Y.; Troadec, D.; Hauss, G.; Skoczylas, F.

    2015-12-01

    Tight sandstones have a low porosity and a very small permeability K. Available models for K do not compare well with measurements. These sandstones are made of SiO_2 grains, with a typical size of several hundreds of micron. These grains are separated by a network of micro-cracks, with sizes ranging between microns down to tens of nm. Therefore, the structure can be schematized by Voronoi polyhedra separated by plane and permeable polygonal micro-cracks. Our goal is to estimate K based on a two scale analysis and to compare the results to measurements. For a particular sample [2], local measurements on several scales include FIB/SEM [3], CMT and 2D SEM. FIB/SEM is selected because the peak pore size given by Mercury Intrusion Porosimetry is of 350nm. FIB/SEM imaging (with 50 nm voxel size) identifies an individual crack of 180nm average opening, whereas CMT provides a connected porosity (individual crack) for 60 nm voxel size, of 4 micron average opening. Numerical modelling is performed by combining the micro-crack network scale (given by 2D SEM) and the 3D micro-crack scale (given by either FIB/SEM or CMT). Estimates of the micro-crack density are derived from 2D SEM trace maps by counting the intersections with scanlines, the surface density of traces, and the number of fracture intersections. K is deduced by using a semi empirical formula valid for identical, isotropic and uniformly distributed fractures [1]. This value is proportional to the micro-crack transmissivity sigma. Sigma is determined by solving the Stokes equation in the micro-cracks measured by FIB/SEM or CMT. K is obtained by combining the two previous results. Good correlation with measured values on centimetric plugs is found when using sigma from CMT data. The results are discussed and further research is proposed. [1] Adler et al, Fractured porous media, Oxford Univ. Press, 2012. [2] Duan et al, Int. J. Rock Mech. Mining Sci., 65, p75, 2014. [3] Song et al, Marine and Petroleum Eng., 65, p63

  17. Transforming Developmental Education in Texas

    ERIC Educational Resources Information Center

    Journal of Developmental Education, 2014

    2014-01-01

    In recent years, with support from the Texas Legislature, the Texas Higher Education Coordinating Board has funded various developmental education initiatives, including research and evaluation efforts, to help Texas public institutions of higher education provide more effective programs and services to underprepared students. Based on evaluation…

  18. Forests of east Texas, 2015

    Treesearch

    Kerry J.W. Dooley

    2017-01-01

    This resource update provides an overview of forest resources in east Texas based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Southern Research Station (SRS) in cooperation with Texas A&M Forest Service. The 254 counties of Texas are consolidated into seven FIA survey units—Southeast (unit 1),...

  19. Texas State Technical College Review.

    ERIC Educational Resources Information Center

    Aumack, Bruce; Blake, Larry J.

    Texas educational legislation for 1991 required the Texas Higher Education Coordinating Board (THECB) to review the operations of, and the continuing need for, each of the four main campuses and five extension centers of the Texas State Technical College System (TSTCS), and to make recommendations concerning the facilities' continuation and/or…

  20. Analysis of Critical Permeabilty, Capillary Pressure and Electrical Properties for Mesaverde Tight Gas Sandstones from Western U.S. Basins

    SciTech Connect

    Alan Byrnes; Robert Cluff; John Webb; John Victorine; Ken Stalder; Daniel Osburn; Andrew Knoderer; Owen Metheny; Troy Hommertzheim; Joshua Byrnes; Daniel Krygowski; Stefani Whittaker

    2008-06-30

    Although prediction of future natural gas supply is complicated by uncertainty in such variables as demand, liquefied natural gas supply price and availability, coalbed methane and gas shale development rate, and pipeline availability, all U.S. Energy Information Administration gas supply estimates to date have predicted that Unconventional gas sources will be the dominant source of U.S. natural gas supply for at least the next two decades (Fig. 1.1; the period of estimation). Among the Unconventional gas supply sources, Tight Gas Sandstones (TGS) will represent 50-70% of the Unconventional gas supply in this time period (Fig. 1.2). Rocky Mountain TGS are estimated to be approximately 70% of the total TGS resource base (USEIA, 2005) and the Mesaverde Group (Mesaverde) sandstones represent the principal gas productive sandstone unit in the largest Western U.S. TGS basins including the basins that are the focus of this study (Washakie, Uinta, Piceance, northern Greater Green River, Wind River, Powder River). Industry assessment of the regional gas resource, projection of future gas supply, and exploration programs require an understanding of reservoir properties and accurate tools for formation evaluation. The goal of this study is to provide petrophysical formation evaluation tools related to relative permeability, capillary pressure, electrical properties and algorithms for wireline log analysis. Detailed and accurate moveable gas-in-place resource assessment is most critical in marginal gas plays and there is need for quantitative tools for definition of limits on gas producibility due to technology and rock physics and for defining water saturation. The results of this study address fundamental questions concerning: (1) gas storage; (2) gas flow; (3) capillary pressure; (4) electrical properties; (5) facies and upscaling issues; (6) wireline log interpretation algorithms; and (7) providing a web-accessible database of advanced rock properties. The following text

  1. Depositional environments and diagenetic features of a Cretaceous clastic sequence, Fox Hills Sandstone of Northern Great Plains Province

    SciTech Connect

    Wilde, E.M.

    1986-08-01

    The Fox Hills Sandstone, youngest formation of the Montana Group, is a geographically extensive, thin unit that is composed primarily of silty sandstone and shale. This formation records the final withdrawal of the Upper Cretaceous epicontinental sea from the Western Interior of the US. It extends from central Canada southward through Montana, the Dakotas, Wyoming, and Colorado. This typical shoreline sequence is exposed along the flanks of the Cedar Creek anticline, which trends southeastward from eastern Montana into North and South Dakota. The upper Fox Hills consists of stacked, upward-fining, trough to planar cross-bedded sandstone bodies. These sequences grade laterally and vertically into interbedded clay and silt units containing root casts and are interpreted as deposits of a braided-stream system. A matrix mineral assemblage of chlorite, montmorillonite, calcite, and minor dolomite is characteristic of distributary channels and river mouth-bar facies. The lower Fox Hills consists of either irregularly stacked upward-coarsening, trough cross-bedded sand sequences or massive sand bodies separated by erosional surfaces. Outcrops locally contain the trace fossil Ophiomorpha or limestone concretions containing marine to brackish-water fossils, and have been interpreted as deposits of a rapidly advancing shoreline and strand plain. In the matrix, illite, kaolinite, and montmorillonite with minor calcite characterize beach, subtidal, and crevasse-splay environments. Diagenetic features include quartz overgrowths, clay alterations of potassium feldspar and rock fragments, and authigenic clay rims. Petrographic evidence indicates multiple source areas for these sediments and the primary influence of depositional environments on clay formation.

  2. Origin of quartz cement in the Tirrawarra Sandstone, Southern Cooper Basin, South Australia

    SciTech Connect

    Rezaee, M.R.; Tingate, P.R.

    1997-01-01

    Quartz cement in siliciclastic sequences is commonly a major diagenetic phase that affects hydrocarbon reservoir quality. Quartz cement is the most abundant authigenic mineral in the fluvio-deltaic Tirrawarra Sandstone and plays an important role in controlling reservoir quality. Petrographic, fluid inclusion, electron microprobe and cathodoluminescence (CL) data from the quartz cement indicate multiple stages of cementation at different temperatures and suggest more than one silica source. CL observations indicate up to six stages of quartz cement in some samples. The stages of quartz cement can be classified into three zones: an innermost zone of brown-luminescing cement (Z1), a middle zone of bright blue-luminescing cement (Z2) and an outer zone of brown-luminescing cement (Z3). Dead oil or bitumen is trapped between Z2 and Z3, indicating that Z3 formed after oil migration commenced. Measurements of homogenization temperatures from fluid inclusions in quartz overgrowths indicate that quartz cement precipitated over a temperature range of 65 to 130 C. Microprobe analysis shows a consistent variation in aluminum between each quartz cement zone. Fluid-inclusion precipitation temperatures and aluminum content have been used to help identify the silica sources for different zones of cement. Considering the temperature of precipitation, very low aluminum content, and the presence of Z3 cement in facies prone to stylolitization, the silica source for the cement is likely to have been pressure solution of detrital quartz at stylolites and grain contacts.

  3. Chromite in Lower Pennsylvanian Nuttall sandstone from West Virginia - Possible Blue Ridge province source

    SciTech Connect

    O'Connor, J.T. )

    1989-08-01

    Detrital chromite grains from heavy mineral separates of three samples of the Lower Pennsylvanian Nuttall Sandstone Member of the New River Formation were examined by use of a reflected-light petrographic microscope, a scanning electron microscope, and an electron microprobe. Some textures observed microscopically in the chromite grains are similar to those in chromite grains in dunite from the Blue Ridge province of North Carolina that has undergone regional metamorphism. Additional exsolution features are also observed in the chromites of this study. The major-oxide compositions of the detrital chromite grains vary more widely than those of the chromites of the Blue Ridge, possibly due to a larger sampling base. The detrital grain compositions (Cr/(Cr + Al), Mg/(Mg + Fe{sup +2})) plot near the fields of the Blue Ridge chromites, although the appearance of both more aluminum-rich and magnesium-poor compositions possibly indicate a higher facies of metamorphism than the Blue Ridge samples studied to date.

  4. Provenance of sandstones from Caledonian nappes in Finnmark, Norway: Implications for Neoproterozoic-Cambrian palaeogeography

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Roberts, D.; Pease, V.

    2016-11-01

    U-Pb detrital zircon age spectra from four formations in the Laksefjord and Kalak nappe complexes, Finnmark Caledonides, northern Norway, show peaks ranging from Neoarchaean through Late Palaeoproterozoic to Late Mesoproterozoic. Together with an extensive database of palaeocurrent flow measurements indicating derivation of the sediments from source regions to the S-SE on the Fennoscandian Shield, the successions in the lower thrust sheets of the Kalak Nappe Complex and the entire Laksefjord Nappe Complex are inferred to be of Baltican origin. These results are contrary to a previous suggestion that the sandstone-dominated Middle Allochthon is exotic to Baltica. The lithostratigraphical successions in these two nappe complexes show a south to north progression from alluvial-fan conglomerates through extensive fluvial to shallow-marine facies into deeper-marine turbiditic sequences. This pattern reflects the palaeogeographic transition from the shallow platform to deep-basinal oceanic development recorded along the c. 2000 km pre-Timanian passive margin of the northeastern Fennoscandian Shield.

  5. Ejecta Dynamics during Hypervelocity Impacts into Dry and Wet Sandstone

    NASA Astrophysics Data System (ADS)

    Hoerth, T.; Schäfer, F.; Thoma, K.; Poelchau, M.; Kenkmann, T.; Deutsch, A.

    2011-03-01

    Hypervelocity impact experiments into dry and water saturated porous Seeberger sandstone were conducted at the two-stage light gas accelerator at the Ernst-Mach-Institute (EMI) and the ejecta dynamics were analyzed.

  6. Resonant Ultrasound Spectroscopy studies of Berea sandstone at high temperature

    SciTech Connect

    Davis, Eric S.; Sturtevant, Blake T.; Sinha, Dipen N.; Pantea, Cristian

    2016-09-04

    Resonant Ultrasound Spectroscopy was used in this paper to determine the elastic moduli of Berea sandstone from room temperature to 478 K. Sandstone is a common component of oil reservoirs, and the temperature range was chosen to be representative of typical downhole conditions, down to about 8 km. In agreement with previous works, Berea sandstone was found to be relatively soft with a bulk modulus of approximately 6 GPa as compared to 37.5 GPa for α-quartz at room temperature and pressure. Finally, it was found that Berea sandstone undergoes a ~17% softening in bulk modulus between room temperature and 385 K, followed by an abnormal behavior of similar stiffening between 385 K and 478 K.

  7. Resonant Ultrasound Spectroscopy studies of Berea sandstone at high temperature

    DOE PAGES

    Davis, Eric S.; Sturtevant, Blake T.; Sinha, Dipen N.; ...

    2016-09-04

    Resonant Ultrasound Spectroscopy was used in this paper to determine the elastic moduli of Berea sandstone from room temperature to 478 K. Sandstone is a common component of oil reservoirs, and the temperature range was chosen to be representative of typical downhole conditions, down to about 8 km. In agreement with previous works, Berea sandstone was found to be relatively soft with a bulk modulus of approximately 6 GPa as compared to 37.5 GPa for α-quartz at room temperature and pressure. Finally, it was found that Berea sandstone undergoes a ~17% softening in bulk modulus between room temperature and 385more » K, followed by an abnormal behavior of similar stiffening between 385 K and 478 K.« less

  8. Martian Sandstone Target Windjana Before and After Brushing

    NASA Image and Video Library

    2014-04-29

    This image from an animation shows a patch of sandstone scrubbed with the Dust Removal Tool, a wire-bristle brush, on NASA Curiosity Mars rover. This rock target is called Windjana, after a gorge in Western Australia.

  9. Nodules of Cemented Sand Grains Within Martian Sandstone

    NASA Image and Video Library

    2016-03-11

    This view from NASA Curiosity shows nodules exposed in sandstone that is part of the Stimson geological unit on Mount Sharp, Mars. The nodules can be seen to consist of grains of sand cemented together.

  10. Pressure sensitivity of low permeability sandstones

    USGS Publications Warehouse

    Kilmer, N.H.; Morrow, N.R.; Pitman, J.K.

    1987-01-01

    Detailed core analysis has been carried out on 32 tight sandstones with permeabilities ranging over four orders of magnitude (0.0002 to 4.8 mD at 5000 psi confining pressure). Relationships between gas permeability and net confining pressure were measured for cycles of loading and unloading. For some samples, permeabilities were measured both along and across bedding planes. Large variations in stress sensitivity of permeability were observed from one sample to another. The ratio of permeability at a nominal confining pressure of 500 psi to that at 5000 psi was used to define a stress sensitivity ratio. For a given sample, confining pressure vs permeability followed a linear log-log relationship, the slope of which provided an index of pressure sensitivity. This index, as obtained for first unloading data, was used in testing relationships between stress sensitivity and other measured rock properties. Pressure sensitivity tended to increase with increase in carbonate content and depth, and with decrease in porosity, permeability and sodium feldspar. However, scatter in these relationships increased as permeability decreased. Tests for correlations between pressure sensitivity and various linear combinations of variables are reported. Details of pore structure related to diagenetic changes appears to be of much greater significance to pressure sensitivity than mineral composition. ?? 1987.

  11. Uranium migration through intact sandstone cores

    NASA Astrophysics Data System (ADS)

    Read, D.; Lawless, T. A.; Sims, R. J.; Butter, K. R.

    1993-06-01

    Uranium is often considered to be a mobile radioelement in the natural environment owing to its tendency to form stable complexes with a number of aqueous anions, particularly in oxidising milieu. A series of infiltration experiments were devised to investigate this migration behaviour under rigidly controlled laboratory conditions. Intact cores of Permo-Triassic Clashach Sandstone were pre-equilibrated with synthetic groundwater solutions and continuous flow-through of uranium monitored together with pH and concentrations of other ions. Prior to performing each experiment a simulation was carried out using a one-dimensional coupled chemical transport code, encompassing a thermodynamic description of the electrical double layer. These calculations together with electron microscopy indicated the potential role played by iron oxyhydroxide grain coatings in retarding the uranium plume. Thus, a second series of experiments was initiated on pre-acidified cores from which all surface exposed iron had been removed, allowing an assessment of the retention capacity of non-ferric components. Taken together, the data clearly illustrate the strong affinity of aqueous uranium species for natural surfaces even under strongly oxidising conditions. The success of the model in predicting a priori the dominant trends in uranium migration behaviour is encouraging and may aid in prioritising analytical requirements for investigations in more complex geochemical situations than those studied here.

  12. Prolific Overton field gas reservoirs within large transverse oolite shoals, Upper Jurassic Haynesville, Eastern Margin East Texas basin

    SciTech Connect

    Glynn, W.G.; Covington, T.E.; Lighty, R.G.; Ahr, W.M.

    1985-02-01

    Late Triassic rifting along a northeast-southwest spreading center in east Texas resulted in basement highs along the eastern margin of the East Texas basin that became sites of extensive ooid shoal deposition during Late Jurassic time. Reservoirs within oolite facies at Overton field contain over 1 tcf of natural gas. These large shoals, each approximately 15 mi (24 km) long and 3 mi (4.8 km) wide, trend north-south as a group and northeast-southwest individually. They are oblique to the basin margin but parallel with Jurassic diffracted tidal currents within the East Texas embayment. Modern Bahamian ooid shoals of similar size, trend, and depositional setting occur at the terminus of the deep Tongue-Of-The-Ocean platform reentrant. Overton field reservoirs are in ooid grainstone shoal facies and in transitional shoal margins of skeletal-oolitic-peloidal grainstones and packstones. Adjacent nonreservoir facies are peloidal-skeletal-siliciclastic wackestones and mudstones. Early diagenesis of grainstone reservoir facies included meteoric dissolution and grain stabilization, resulting in abundant chalky intraparticle porosity and equant and bladed calcite cements filling interparticle porosity. Subsequent burial diagenesis resulted in intense solution compaction and coarse equant calcite and saddle crystal dolomite that occluded remaining interparticle porosity. Whole-rock trace element analysis indicates greatest diagenetic flushing (less magnesium, strontium) in porous zones. Stable isotopes for grains and cements show strong overprint of later burial diagenesis, with greater depletion of delta/sup 18/O in reservoir facies. However, hydrocarbons were emplaced prior to late cementation, and unlike other Jurassic Gulf Coast reservoirs, deep burial diagenesis provided no late-stage formation of porosity.

  13. The flora of the Catahoula Sandstone

    USGS Publications Warehouse

    Berry, Edward Wilber

    1916-01-01

    During the progress of my studies of the fossil floras of the Gulf Coastal Plain, embracing all horizons from the Lower Cretaceous to the Pleistocene and prosecuted under the general direction of T. Wayland Vaughan, material representing the floras of all the major stratigraphic units in the area extending from western Florida to central Texas has been discovered. Field work and office studies of all these floras have proceeded more or less simultaneously, and a large amount of manuscript in various stages of completion has been accumulated. The floras of the Upper Cretaceous and Eocene of South Carolina and Georgia have been described and a report on the very large lower Eocene floras is now in press.

  14. Algorithms of Crescent Structure Detection in Human Biological Fluid Facies

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, V. R.; Malenova, O. E.; Yashina, A. S.

    2017-05-01

    One of the effective methods of early medical diagnosis is based on the image analysis of human biological fluids. In the process of fluid crystallization there appear characteristic patterns (markers) in the resulting layer (facies). Each marker is a highly probable sign of some pathology even at an early stage of a disease development. When mass health examination is carried out, it is necessary to analyze a large number of images. That is why, the problem of algorithm and software development for automated processing of images is rather urgent nowadays. This paper presents algorithms to detect a crescent structures in images of blood serum and cervical mucus facies. Such a marker indicates the symptoms of ischemic disease. The algorithm presented detects this marker with high probability when the probability of false alarm is low.

  15. Killian's photographs: "Facies dolorosa", the countenance of pain.

    PubMed

    Luger, Veronika; Feistle, Frank; Feistle, Gerhard; Feistle, Jörg

    2016-07-01

    The book "Facies dolorosa" by Hans Killian, first published in 1934 and later in 1956 and 1967 as extended and annotated versions, comprises ~ 70 photographs depicting facial expressions of patients suffering from various diseases. The photographs in black and white are analyzed and annotated by the author with the purpose of providing clinicians, and especially young doctors, with an insight into the medical and scientific value of facial expression of pain in the diagnosis, staging, and prognosis of severe disease. This historical review of a book no longer in print is part of a 2016 commemorative publication marking the 60th anniversary of the publication of the "Facies dolorosa" by Dustri Medical and Scientific Publications, Munich, Germany and Rockledge, USA.

  16. Alluvial fan facies of the Yongchong Basin: Implications for tectonic and paleoclimatic changes during Late Cretaceous in SE China

    NASA Astrophysics Data System (ADS)

    Chen, Liuqin; Steel, Ronald J.; Guo, Fusheng; Olariu, Cornel; Gong, Chenglin

    2017-02-01

    Late Cretaceous continental redbeds, the Guifeng Group of the Yongchong Basin in SE China have been investigated to conduct detailed fan facies description and interpretation. Tectonic activities determined the alluvial fan development along the basin margin, but the alluvial facies was linked with paleoclimate changes. The Guifeng Group is divided into the Hekou, Tangbian and Lianhe formations in ascending order. The Hekou conglomerates are typically polymict, moderately sorted with erosional bases, cut-and-fill features, normal grading and sieve deposits, representing dominant stream-flows on alluvial fans during the initial opening stage of the basin infill. The Tangbian Formation, however, is characterized by structureless fine-grained sediments with dispersed coarse clasts, and couplets of conglomerate and sandstone or siltstone and mudstone, recording a change to a playa and ephemeral lake environments with occasional stream flooding, thus indicating a basin expanding stage. The hallmark of the Lianhe Formation is disorganized, poorly sorted conglomerates lack of erosional bases, and a wide particle-size range from clay to boulders together reflect mud-rich debris-flows accumulating on fans, likely related to reactivation of faulting along the northwestern mountain fronts during a post-rift stage. The depositional system changes from stream-flows up through playa with ephemeral streams to debris-flows during the accumulation of the three formations are thus attributed to different source rocks and climatic conditions. Therefore, the fluvial-dominated fans of the Hekou Formation recorded a subhumid paleoclimate (Coniacian-Santonian Age). The dominant semiarid climate during the Campanian Age produced abundant fine-grained sediments in the playa and ephemeral lake environments of the Tangbian Formation. A climatic change towards more humidity during the late stage of the Guifeng Group (Maastrichtian Age) probably yielded high deposition rate of coarse clasts in

  17. Muddy and dolomitic rip-up clasts in Triassic fluvial sandstones: Origin and impact on potential reservoir properties (Argana Basin, Morocco)

    NASA Astrophysics Data System (ADS)

    Henares, Saturnina; Arribas, Jose; Cultrone, Giuseppe; Viseras, Cesar

    2016-06-01

    The significance of rip-up clasts as sandstone framework grains is frequently neglected in the literature being considered as accessory components in bulk sandstone composition. However, this study highlights the great value of muddy and dolomitic rip-up clast occurrence as: (a) information source about low preservation potential from floodplain deposits and (b) key element controlling host sandstone diagenetic evolution and thus ultimate reservoir quality. High-resolution petrographic analysis on Triassic fluvial sandstones from Argana Basin (T6 and T7/T8 units) highlights the significance of different types of rip-up clasts as intrabasinal framework components of continental sediments from arid climates. On the basis of their composition and ductility, three main types are distinguished: (a) muddy rip-up clasts, (b) dolomitic muddy rip-up clasts and (c) dolomite crystalline rip-up clasts. Spatial distribution of different types is strongly facies-related according to grain size. Origin of rip-up clasts is related to erosion of coeval phreatic dolocretes, in different development stages, and associated muddy floodplain sediments. Cloudy cores with abundant inclusions and clear outer rims of dolomite crystals suggest a first replacive and a subsequent displacive growth, respectively. Dolomite crystals are almost stoichiometric. This composition is very similar to that of early sandstone dolomite cement, supporting phreatic dolocretes as dolomite origin in both situations. Sandstone diagenesis is dominated by mechanical compaction and dolomite cementation. A direct correlation exists between: (1) muddy rip-up clast abundance and early reduction of primary porosity by compaction with irreversible loss of intergranular volume (IGV); and (2) occurrence of dolomitic rip-up clasts and dolomite cement nucleation in host sandstone, occluding adjacent pores but preserving IGV. Both processes affect reservoir quality by generation of vertical and 3D fluid flow baffles and

  18. Provenance and geochronology of Cenozoic sandstones of northern Borneo

    NASA Astrophysics Data System (ADS)

    van Hattum, M. W. A.; Hall, R.; Pickard, A. L.; Nichols, G. J.

    2013-10-01

    The Crocker Fan of Sabah was deposited during subduction of the Proto-South China Sea between the Eocene and Early Miocene. Collision of South China microcontinental blocks with Borneo in the Early Miocene terminated deep water sedimentation and resulted in the major regional Top Crocker Unconformity (TCU). Sedimentation of fluvio-deltaic and shallow marine character resumed in the late Early Miocene. The Crocker Fan sandstones were derived from nearby sources in Borneo and nearby SE Asia, rather than distant Asian and Himalayan sources. The Crocker Fan sandstones have a mature composition, but their textures and heavy mineralogy indicate they are first-cycle sandstones, mostly derived from nearby granitic source rocks, with some input of metamorphic, sedimentary and ophiolitic material. The discrepancy between compositional maturity and textural immaturity is attributed to the effects of tropical weathering. U-Pb ages of detrital zircons are predominantly Mesozoic. In the Eocene sandstones Cretaceous zircons dominate and suggest derivation from granites of the Schwaner Mountains of southern Borneo. In Oligocene sandstones Permian-Triassic and Palaeoproterozoic zircons become more important, and are interpreted to be derived from Permian-Triassic granites and Proterozoic basement of the Malay Tin Belt. Miocene fluvio-deltaic and shallow marine sandstones above the TCU were mostly recycled from the deformed Crocker Fan in the rising central mountain range of Borneo. The provenance of the Tajau Sandstone Member of the Lower Miocene Kudat Formation in north Sabah is strikingly different from other Miocene and older sandstones. Sediment was derived mainly from granitic and high-grade metamorphic source rocks. No such rocks existed in Borneo during the Early Miocene, but potential sources are present on Palawan, to the north of Borneo. They represent continental crust from South China and subduction-related metamorphic rocks which formed an elevated region in the Early

  19. Bayesian inversion for facies detection: An extensible level set framework

    NASA Astrophysics Data System (ADS)

    Cardiff, M.; Kitanidis, P. K.

    2009-10-01

    In many cases, it has been assumed that the variability in hydrologic parameters can be adequately described through a simple geostatistical model with a given variogram. In other cases, variability may be best described as a series of "jumps" in parameter behavior, e.g., those that occur at geologic facies contacts. When using indirect measurements such as pump tests to try to map such heterogeneity (during inverse modeling), the resulting images of the subsurface are always affected by the assumptions invoked. In this paper, we discuss inversion for parameter fields where prior information has suggested that major variability can be described by boundaries between geologic units or facies. In order to identify such parameter fields, we propose a Bayesian level set inversion protocol framework, which allows for flexible zones of any shape, size, and number. We review formulas for defining facies locations using the level set method and for moving the boundaries between zones using a gradient-based technique that improves fit through iterative deformation of the boundaries. We describe the optimization algorithm employed when multiple level set functions are used to represent a field with more than two facies. We extend these formulas to the investigation of the inverse problem in a Bayesian context in which prior information is taken into account and through which measures of uncertainty can be derived. We also demonstrate that the level set method is well suited for joint inversion problems and present a strategy for integrating different data types (such as hydrologic and geophysical) without assuming strict petrophysical relations. Our framework for joint inversion also contrasts with many previous methods in that all data sources (e.g., both hydrologic and geophysical) contribute to boundary delineation at once.

  20. Comparison of four approaches to a rock facies classification problem

    NASA Astrophysics Data System (ADS)

    Dubois, Martin K.; Bohling, Geoffrey C.; Chakrabarti, Swapan

    2007-05-01

    In this study, seven classifiers based on four different approaches were tested in a rock facies classification problem: classical parametric methods using Bayes' rule, and non-parametric methods using fuzzy logic, k-nearest neighbor, and feed forward-back propagating artificial neural network. Determining the most effective classifier for geologic facies prediction in wells without cores in the Panoma gas field, in Southwest Kansas, was the objective. Study data include 3600 samples with known rock facies class (from core) with each sample having either four or five measured properties (wire-line log curves), and two derived geologic properties (geologic constraining variables). The sample set was divided into two subsets, one for training and one for testing the ability of the trained classifier to correctly assign classes. Artificial neural networks clearly outperformed all other classifiers and are effective tools for this particular classification problem. Classical parametric models were inadequate due to the nature of the predictor variables (high dimensional and not linearly correlated), and feature space of the classes (overlapping). The other non-parametric methods tested, k-nearest neighbor and fuzzy logic, would need considerable improvement to match the neural network effectiveness, but further work, possibly combining certain aspects of the three non-parametric methods, may be justified.

  1. Comparison of four approaches to a rock facies classification problem

    USGS Publications Warehouse

    Dubois, M.K.; Bohling, G.C.; Chakrabarti, S.

    2007-01-01

    In this study, seven classifiers based on four different approaches were tested in a rock facies classification problem: classical parametric methods using Bayes' rule, and non-parametric methods using fuzzy logic, k-nearest neighbor, and feed forward-back propagating artificial neural network. Determining the most effective classifier for geologic facies prediction in wells without cores in the Panoma gas field, in Southwest Kansas, was the objective. Study data include 3600 samples with known rock facies class (from core) with each sample having either four or five measured properties (wire-line log curves), and two derived geologic properties (geologic constraining variables). The sample set was divided into two subsets, one for training and one for testing the ability of the trained classifier to correctly assign classes. Artificial neural networks clearly outperformed all other classifiers and are effective tools for this particular classification problem. Classical parametric models were inadequate due to the nature of the predictor variables (high dimensional and not linearly correlated), and feature space of the classes (overlapping). The other non-parametric methods tested, k-nearest neighbor and fuzzy logic, would need considerable improvement to match the neural network effectiveness, but further work, possibly combining certain aspects of the three non-parametric methods, may be justified. ?? 2006 Elsevier Ltd. All rights reserved.

  2. Diagenesis Along Fractures in an Eolian Sandstone, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Ming, D. W.; Yen, A. S.; Rampe, E. B.; Grotzinger, J. P.; Blake, D. F.; Bristow, T. F.; Chipera, S. J.; Downs, R.; Morris, R. V.; Morrison, S. M.; Vaniman, D. T.; Gellert, R.; Sutter, B.; Treiman, A. H.

    2016-01-01

    The Mars Science Laboratory rover Curiosity has been exploring sedimentary deposits in Gale crater since August 2012. The rover has traversed up section through approx.100 m of sedimentary rocks deposited in fluvial, deltaic, lacustrine, and eolian environments (Bradbury group and overlying Mount Sharp group). The Stimson formation lies unconformable over a lacustrine mudstone at the base of the Mount Sharp group and has been interpreted to be a cross-bedded sandstone of lithified eolian dunes. Mineralogy of the unaltered Stimson sandstone consists of plagioclase feldspar, pyroxenes, and magnetite with minor abundances of hematite, and Ca-sulfates (anhydrite, bassanite). Unaltered sandstone has a composition similar to the average Mars crustal composition. Alteration "halos" occur adjacent to fractures in the Stimson. Fluids passing through these fractures have altered the chemistry and mineralogy of the sandstone. Silicon and S enrichments and depletions in Al, Fe, Mg, Na, K, Ni and Mn suggest aqueous alteration in an open hydrologic system. Mineralogy of the altered Stimson is dominated by Ca-sulfates, Si-rich X-ray amorphous materials along with plagioclase feldspar, magnetite, and pyroxenes, but less abundant in the altered compared to the unaltered Stimson sandstone and lower pyroxene/plagioclase feldspar. The mineralogy and geochemistry of the altered sandstone suggest a complicated history with several (many?) episodes of aqueous alteration under a variety of environmental conditions (e.g., acidic, alkaline).

  3. The Middle Jurassic Entrada Sandstone near Gallup, New Mexico

    USGS Publications Warehouse

    Robertson, J.F.; O'Sullivan, R. B.

    2001-01-01

    Near Gallup, New Mexico, the Middle Jurassic Entrada Sandstone consists of, in ascending order, the Iyanbito Member, the Rehoboth Member, and an upper sandstone member. The Rehoboth Member is named herein to replace the middle siltstone member, with a type section located 26 km east of Gallup. The Iyanbito Member has been erroneously equated with the Wingate Sandstone of northeast Arizona, and the Rehoboth Member has been miscorrelated with the Dewey Bridge Member of the Entrada in Utah. The Dewey Bridge is an older unit that does not extend into New Mexico. The Iyanbito Member, east of Gallup, overlies the J-2 unconformity and the eroded tops of the Owl Rock and Petrified Forest Members of the Chinle Formation. The Wingate Sandstone of the Lower Jurassic Glen Canyon Group overlies the J-0 unconformity and the underlying Rock Point Member (topmost unit) of the Chinle Formation in northeast Arizona. Both the Wingate Sandstone and the Rock Point Member are missing east of Gallup below the J-2 unconformity. Similarly, the Wingate is missing southwest of Gallup, near Lupton, Arizona, but the Rock Point Member is present and underlies the Iyanbito from Zuni northward to Toadlena, New Mexico. The Wingate and other formations of the Glen Canyon Group thin and wedge out southward and eastward in northeast Arizona. The J-2 unconformity truncates the Wingate Sandstone and the underlying J-0 unconformity, 5 km north of Toadlena.

  4. Modeling CO2 distribution in a heterogeneous sandstone reservoir: the Johansen Formation, northern North Sea

    NASA Astrophysics Data System (ADS)

    Sundal, Anja; Miri, Rohaldin; Petter Nystuen, Johan; Dypvik, Henning; Aagaard, Per

    2013-04-01

    The last few years there has been broad attention towards finding permanent storage options for CO2. The Norwegian continental margin holds great potential for storage in saline aquifers. Common for many of these reservoir candidates, however, is that geological data are sparse relative to thoroughly mapped hydrocarbon reservoirs in the region. Scenario modeling provides a method for estimating reservoir performances for potential CO2 storage sites and for testing injection strategies. This approach is particularly useful in the evaluation of uncertainties related to reservoir properties and geometry. In this study we have tested the effect of geological heterogeneities in the Johansen Formation, which is a laterally extensive sandstone and saline aquifer at burial depths of 2 - 4 km, proposed as a suitable candidate for CO2 storage by Norwegian authorities. The central parts of the Johansen Formation are underlying the operating hydrocarbon field Troll. In order not to interfere with ongoing gas production, a potential CO2 injection well should be located at a safe distance from the gas reservoir, which consequently implies areas presently without well control. From 3D seismic data, prediction of spatial extent of sandstone is possible to a certain degree, whereas intra-reservoir flow baffles such as draping mudstone beds and calcite cemented layers are below seismic resolution. The number and lateral extent of flow baffles, as well as porosity- and permeability distributions are dependent of sedimentary facies and diagenesis. The interpretation of depositional environment and burial history is thus of crucial importance. A suite of scenario models was established for a potential injection area south of the Troll field. The model grids where made in Petrel based on our interpretations of seismic data, wire line logs, core and cuttings samples. Using Eclipse 300 the distribution of CO2 is modeled for different geological settings; with and without the presence of

  5. Arctic Creek facies, Arctic National Wildlife Refuge, Northeastern Alaska

    SciTech Connect

    Decker, J.; Camber, W.; Vandergon, M.A.; Crowder, R.K.

    1988-01-01

    The Arctic Creek section is dissimilar to the typical Cretaceous section exposed elsewhere in Ignek Valley. The more typical Ignek Valley sequence consists of Kingak Shale (Jurassic to Neocomian), Kemik Sandstone (Hauterivian), Pebble Shale (Hauterivian-Barremian), Hue Shale (Aptian.to Santonian), and turbidites of the Canning Formation (Campanian to Paleocene). The two main differences that distinguish the Arctic Creek section from the typical Ignek Valley section are: (1) lack of the regionally persistent Kemik Sandstone in the Arctic Creek section, and (2) lack of Albian turbidites in the typical Ignek Valley section. The Arctic Creek section is more similar to the Cretaceous section exposed at Bathtub Ridge about 180 km to the southeast. The Bathtub Ridge section consists of black shale with local siltstone beds (Jurassic to Lower Cretaceous), manganiferous shale, interbedded shale and siltstone turbidites (Albian), and sandstone turbidites (Albian.). The authors believe that the Arctic Creek and Bathtub Ridge sections were once part of a continuous depositional basin, and that the Arctic Creek section has been thrust northward into juxtaposition with the typical Ignek Valley strata.

  6. Texas-Oklahoma

    Atmospheric Science Data Center

    2014-05-15

    article title:  Texas-Oklahoma Border     View ... important resources for farming, ranching, public drinking water, hydroelectric power, and recreation. Both originate in New Mexico and ... NASA's Goddard Space Flight Center, Greenbelt, MD. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science ...

  7. Outdoor Education in Texas.

    ERIC Educational Resources Information Center

    Myers, Ray H.

    In Dallas in 1970, high school outdoor education began as a cocurricular woods and waters boys' club sponsored by a community sportsman. Within one year, it grew into a fully accredited, coeducational, academic course with a curriculum devoted to the study of wildlife in Texas, ecology, conservation, hunting, firearm safety, fishing, boating and…

  8. Earth Observation - Texas Wildfire

    NASA Image and Video Library

    2011-06-19

    ISS028-E-008375 (21 June 2011) --- One of the Expedition 28 crew members aboard the International Space Station, flying at an altitude of approximately 235 statute miles, on June 21 spotted and photographed this image of one of the major Texas wildfires currently burning up massive acreage. This one is near the Sabine River, southeast of Kirbyville.

  9. Tornado from Texas.

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1996-01-01

    Santa Fe School Superintendent Yvonne Gonzales, the "Texas Tornado," was hired to fix a 40% student-dropout rate and a white/Hispanic gap in achievement test scores. Gonzales is an avid integrationist; relies on humor, appeasement, and persuasion tactics; and has alienated some school employees by increasing central office…

  10. The Woodlands, Texas.

    ERIC Educational Resources Information Center

    McHaney, Larry J.; Bernhardt, Jerry

    1988-01-01

    The authors describe the "central project" concept for implementing technology education while addressing education reform. The central project is a topic around which students, teachers, administrators, and the community focus their energies as a team. At McCullough High School (Texas), the central project involved design and…

  11. Tornado from Texas.

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1996-01-01

    Santa Fe School Superintendent Yvonne Gonzales, the "Texas Tornado," was hired to fix a 40% student-dropout rate and a white/Hispanic gap in achievement test scores. Gonzales is an avid integrationist; relies on humor, appeasement, and persuasion tactics; and has alienated some school employees by increasing central office…

  12. East Texas Quilts.

    ERIC Educational Resources Information Center

    Whiteside, Karen, Ed.

    1986-01-01

    Patchwork quilting is an original folk art in the United States. Pilgrims first used worn out scraps of cloth to make bed covers in an age of scarcity. Featured here are stories on East Texas Quilts, their origins, the love and hard work which goes into the making of a quilt (Ira Barr and others). The techniques needed to construct a quilt are…

  13. Texas and SREB

    ERIC Educational Resources Information Center

    Southern Regional Education Board (SREB), 2009

    2009-01-01

    The Southern Regional Education Board (SREB) is a nonprofit organization that works collaboratively with Texas and 15 other member states to improve education at every level--from pre-K to postdoctoral study--through many effective programs and initiatives. SREB's "Challenge to Lead" Goals for Education, which call for the region to lead…

  14. Outdoor Education in Texas.

    ERIC Educational Resources Information Center

    Myers, Ray H.

    In Dallas in 1970, high school outdoor education began as a cocurricular woods and waters boys' club sponsored by a community sportsman. Within one year, it grew into a fully accredited, coeducational, academic course with a curriculum devoted to the study of wildlife in Texas, ecology, conservation, hunting, firearm safety, fishing, boating and…

  15. East Texas Quilts.

    ERIC Educational Resources Information Center

    Whiteside, Karen, Ed.

    1986-01-01

    Patchwork quilting is an original folk art in the United States. Pilgrims first used worn out scraps of cloth to make bed covers in an age of scarcity. Featured here are stories on East Texas Quilts, their origins, the love and hard work which goes into the making of a quilt (Ira Barr and others). The techniques needed to construct a quilt are…

  16. Texas Irrigation Situation

    USDA-ARS?s Scientific Manuscript database

    The irrigation situation in Texas is an interaction between hydrology and water policies. In 2012, according to National Agricultural Statistical Service (NASS) four High Plains counties, Gainesville, Yoakum, Terry and Cochran, accounted for approximately 60% of the 150,000 acres of peanut productio...

  17. Texas Hunter Education Manual.

    ERIC Educational Resources Information Center

    Hall, Steve

    This handbook serves as a reference for the mandatory hunter education course in Texas. The "Introduction" explains hunter education's goal to produce safe, knowledgeable, responsible, and informed hunters. It also gives information related to hunting opportunities, administration, and management. Chapter 2, "Our Hunting…

  18. Texas Migrant Council, Inc.

    ERIC Educational Resources Information Center

    Villarreal, Oscar L.

    Operating various programs, the Texas Migrant Council, a multi-service agency, administers assistance to migrants during their stay in their home base state, as well as on their migrant trek. Its Head Start program serves mobile migrant children from the ages of 0 to 5 and gives continuity of services by following them to the northern states…

  19. Library Laws of Texas.

    ERIC Educational Resources Information Center

    Getz, Richard E., Comp.

    Compiled to provide a central reference point for all legislative information pertaining to libraries in the State of Texas, this publication includes all pertinent legislation as amended through the 71st Legislature, 1989, Regular Session. This update of the 1980 edition has been expanded to include statutes pertaining to the school and academic…

  20. Texas Hunter Education Manual.

    ERIC Educational Resources Information Center

    Hall, Steve

    This handbook serves as a reference for the mandatory hunter education course in Texas. The "Introduction" explains hunter education's goal to produce safe, knowledgeable, responsible, and informed hunters. It also gives information related to hunting opportunities, administration, and management. Chapter 2, "Our Hunting…

  1. The Woodlands, Texas.

    ERIC Educational Resources Information Center

    McHaney, Larry J.; Bernhardt, Jerry

    1988-01-01

    The authors describe the "central project" concept for implementing technology education while addressing education reform. The central project is a topic around which students, teachers, administrators, and the community focus their energies as a team. At McCullough High School (Texas), the central project involved design and…

  2. Library Laws of Texas.

    ERIC Educational Resources Information Center

    Seidenberg, Ed, Ed.

    Compiled to provide a central reference point for all legislative information pertaining to libraries in the state of Texas, this publication includes all pertinent legislation as amended through the 66th Legislature, Regular Session, 1979. It contains articles dealing specifically with archives, buildings and property, city libraries, non-profit…

  3. Library Laws of Texas.

    ERIC Educational Resources Information Center

    Getz, Richard E., Comp.

    Compiled to provide a central reference point for all legislative information pertaining to libraries in the State of Texas, this publication includes all pertinent legislation as amended through the 71st Legislature, 1989, Regular Session. This update of the 1980 edition has been expanded to include statutes pertaining to the school and academic…

  4. Geohydrology of the Delaware Basin and vicinity, Texas and New Mexico

    USGS Publications Warehouse

    Richey, S.F.; Wells, J.G.; Stephens, K.T.

    1985-01-01

    The Delaware Basin study area includes four major aquifers: Capitan aquifer, Rustler Formation, Santa Rosa Sandstone (Dockum Group), and aquifers in the Cenozoic alluvium. Water from the Capitan aquifer is used for domestic and irrigation purposes in Eddy County, New Mexico, and for irrigation and industrial purposes in Texas. Available analyses indicate that dissolved solids concentrations range from 303 to 31,700 mg/L, chloride concentrations range from 16 to 16,689 mg/L, and fluoride concentrations range from 0.5 to 3.0 mg/L. The Rustler Formation contains water that generally is not suitable for domestic use because of its salinity. Chloride concentrations range from 15 to 210,000 mg/L, and dissolved solids concentrations range from 286 to 325,800 mg/L. Fluoride concentrations range from 0.5 to 11.4 mg/L. Water from this aquifer is used for irrigation and stock watering where it is of suitable quality. The Santa Rosa Sandstone is the principal source of groundwater in the western third of Lea County and in the eastern part of Eddy County. In parts of Texas, the Santa Rosa Sandstone and the Cenozoic alluvium are hydraulically connected and are called the Allurosa aquifer. The Santa Rosa Sandstone-Allurosa aquifer is the source of municipal supply for the cities of Barstow, Pecos, Monahans, and Kermit, Texas. Water quality is variable. For those analyses where the Santa Rosa Sandstone is a distinct entity, chloride concentrations range from 10 to 4,800 mg/L, dissolved solids concentrations range from 205 to 2,990 mg/L, and fluoride concentrations range from 0.4 to 5.0 mg/L. Water from the Cenozoic alluvium is used extensively for public water supplies, irrigation, industry, livestock watering, and rural-domestic supply throughout the Delaware Basin. The quality of water in the Cenozoic alluvium is variable. Chloride concentrations range from 5 to 7,400 mg/L, dissolved solids concentrations range from 188 to 15,000 mg/L, and fluoride concentrations range from 0

  5. Facies analysis of yedoma thermokarst lakes on the northern Seward Peninsula, Alaska

    NASA Astrophysics Data System (ADS)

    Farquharson, Louise; Anthony, Katey Walter; Bigelow, Nancy; Edwards, Mary; Grosse, Guido

    2016-07-01

    Thermokarst lakes develop as a result of the thaw and collapse of ice-rich, permanently frozen ground (permafrost). Of particular sedimentological importance are thermokarst lakes forming in late Pleistocene icy silt (yedoma), which dramatically alter the land surface by lowering surface elevation and redistributing upland sediment into lower basins. Our study provides the first description of yedoma thermokarst lake sedimentology based on the cross-basin sampling of an existing lake. We present lake sediment facies descriptions based on data from sediment cores from two thermokarst lakes of medium depth, Claudi and Jaeger (informal names), which formed in previously non thermokarst-affected upland yedoma on the northern Seward Peninsula, Alaska. We identify four prominent facies using sedimentological, biogeochemical, and macrofossil indicators: a massive silt lacking aquatic macrofossils and other aquatic indicators situated below a sub-lacustrine unconformity (Facies 1); two basal deposits: interbedded organic silt and chaotic silt (Facies 2-3); and a silt-rich mud (Facies 4). Facies 1 is interpreted as yedoma that has thawed during lake formation. Facies 3 formed adjacent to the margin due to thaw and collapse events from the lake shore. Material from Facies 3 was reworked by wave action to form Facies 2 in a medium energy margin environment. Facies 4 formed in a lower energy environment toward the lake basin center. This facies classification and description should enhance our ability (i) to interpret the spatial and temporal development of lakes and (ii) to reconstruct long-term patterns of landscape change.

  6. Catalogue of Texas spiders

    PubMed Central

    Dean, David Allen

    2016-01-01

    Abstract This catalogue lists 1,084 species of spiders (three identified to genus only) in 311 genera from 53 families currently recorded from Texas and is based on the “Bibliography of Texas Spiders” published by Bea Vogel in 1970. The online list of species can be found at http://pecanspiders.tamu.edu/spidersoftexas.htm. Many taxonomic revisions have since been published, particularly in the families Araneidae, Gnaphosidae and Leptonetidae. Many genera in other families have been revised. The Anyphaenidae, Ctenidae, Hahniidae, Nesticidae, Sicariidae and Tetragnathidae were also revised. Several families have been added and others split up. Several genera of Corinnidae were transferred to Phrurolithidae and Trachelidae. Two genera from Miturgidae were transferred to Eutichuridae. Zoridae was synonymized under Miturgidae. A single species formerly in Amaurobiidae is now in the Family Amphinectidae. Some trapdoor spiders in the family Ctenizidae have been transferred to Euctenizidae. Gertsch and Mulaik started a list of Texas spiders in 1940. In a letter from Willis J. Gertsch dated October 20, 1982, he stated “Years ago a first listing of the Texas fauna was published by me based largely on Stanley Mulaik material, but it had to be abandoned because of other tasks.” This paper is a compendium of the spiders of Texas with distribution, habitat, collecting method and other data available from revisions and collections. This includes many records and unpublished data (including data from three unpublished studies). One of these studies included 16,000 adult spiders belonging to 177 species in 29 families. All specimens in that study were measured and results are in the appendix. Hidalgo County has 340 species recorded with Brazos County at 323 and Travis County at 314 species. These reflect the amount of collecting in the area. PMID:27103878

  7. Pressure Solution Creep and Textural Softening in Greenschist Facies Phyllonites

    NASA Astrophysics Data System (ADS)

    Wintsch, R. P.; Attenoukon, M.; Kunk, M. J.; McAleer, R. J.; Wathen, B.; Yi, D.

    2016-12-01

    We have found evidence for dissolution-precipitation creep (DPC) in phyllites and phyllonites naturally deformed at greenschist facies conditions. Since the experiments of Kronenberg et al. (1990) and Mares and Kronenberg (1993) micas are known to be among the weakest of rock-forming minerals. They deform by dislocation glide in their basal plane and when these micas are aligned and contiguous in an orientation favorable for glide they tend to localize strain into shear zones. Therefore, these closed-system experiments suggest that dislocation glide should be the dominant deformation mechanism in mica-rich shear zones from near surface through greenschist facies conditions. In contrast, in naturally deformed rocks we have found strong textural and chemical evidence that micas deform by dissolution-precipitation creep in phyllites at upper and lower greenschist facies conditions. In the Littleton Formation (N.H.) we find retrograde muscovite (pg5)-rich folia (Sn) truncating amphibolite facies Na-rich muscovite and biotite grains that define earlier foliations. Na-rich muscovite grains are also selectively replaced along crenulation axes and boudin necks where plastic and elastic strain are highest. In biotite grade regional metamorphic rocks in the Tananao schist of Taiwan muscovite-rich folia (Sn) truncate crenulated muscovite-biotite schists at high angles. In still lower (chlorite) grade phyllonitic fault zones marking terrane boundaries in southern New England (East Derby shear zone) and in Taiwan (Daugan shear zone) crenulated older fabrics are cut by new undeformed muscovite grains in chlorite-free planar folia. Further evidence for recrystallization rather than dislocation glide comes from the 40Ar/39Ar ages of muscovite in the new Sn folia younger than the age of the truncated folia. The younger ages in each case demonstrate that recrystallization was activated at lower shear stresses than dislocation glide, and that the recrystallization occurred at lower

  8. Upper Jurassic (Oxfordian) Smackover Facies characterization at Little Cedar Creek Field, Conecuh County, Alabama

    NASA Astrophysics Data System (ADS)

    Ridgway, John Grayson

    The Upper Jurassic (Oxfordian) Smackover Formation is a shallow-marine carbonate unit in the subsurface of the U.S. Gulf Coast, spanning from south Texas to west Florida. This field case-study focuses on Little Cedar Creek Field located in southeastern Conecuh County, Alabama. The objectives of this study are to (1) construct a 3-D depositional model for the Smackover Formation at Little Cedar Creek Field; (2) establish a sequence stratigraphic framework for the construction of the depositional model; (3) characterize and map lithofacies with high resource potential based on the depositional model; and (4) demonstrate the use of the depositional model to maximize hydrocarbon recovery in the field area. Little Cedar Creek Field is located near the up-dip limit of the Smackover Formation. The top of the Smackover is found at depths between 10,000 to 12,000 feet, and the formation ranges in thickness from 60 to 120 feet. The Smackover Formation overlies the Callovian-Oxfordian Norphlet Formation and underlies the Kimmeridgian Haynesville Formation. The petroleum reservoirs in Little Cedar Creek Field, unlike most Smackover fields in the eastern Gulf region, are composed predominantly of limestone, not dolomite, and do not possess a Buckner Anhydrite top seal immediately above the reservoir. Beginning from the top of the Smackover, the facies are: (S-1) Peritidal lime mudstone-wackestone; (S-2) tidal channel conglomeratic floatstone-rudstone; (S-3) peloid-ooid shoal grainstone-packstone; (S-4) subtidal lime wackestone-mudstone; (S-5) microbially-influenced packstone-wackestone; (S-6) microbial (thrombolite) boundstone; and (S-7) transgressive lime mudstone-dolostone. Production is from both the thrombolite boundstone and shoal grainstone facies, though pressure and fluid data indicate no communication between the two reservoirs. The data indicate that the microbial communities developed on subtle topographic highs overlying the transgressive lime mudstone-dolostone in

  9. Dynamic triggering during rupture nucleation in sandstone

    NASA Astrophysics Data System (ADS)

    Chanard, K.; Nicolas, A.; Latour, S.; Hatano, T.; Vinciguerra, S.; Schubnel, A.

    2016-12-01

    Fluid induced stress perturbations in the crust at seismogenic depths can be caused by various sources, such as deglaciation unloading, magmatic intrusion or fluid injection and withdrawal. Numbers of studies have robustly shown their link to earthquake triggering. However, the role of small periodic stress variations induced by solid earth and oceanic tides or seasonal hydrology in the seismic cycle, of the order of a few kPa, remains unclear. Indeed, the existence or absence of correlation between these loading phenomena and earthquakes have been equally proposed in the literature. To investigate this question, we performed a set of triaxial deformation experiments on porous water-saturated Fontainebleau sandstones. Rock samples were loaded by the combined action of steps of constant stress (creep), intended to simulate tectonic loading and small sinusoidal pore pressure variations with a range of amplitudes, analogous to tides or seasonal loading. All tests were conducted at a regulated temperature of 35C and a constant 35 MPa confining pressure. Our experimental results show that (1) pore pressure oscillations do not seem to influence the deformation rate at which the rock fails, (2) they correlate with acoustic emissions. Even more interestingly, we observe a progressive increase of the correlation coefficient in time as the rock approaches failure. The correlation coefficient is also sensitive to the amplitude of pore pressure oscillations as larger oscillations produce higher correlation levels. Finally, we show that, in the last hours of creep before failure, acoustic emissions occur significantly more when the pore pressure is at its lowest. This suggest that the correlation of small stress perturbations and acoustic emissions depend on the state stress of a rock and the amplitude of the perturbations and that emissions occur more likely when cracks are unclamped.

  10. Fault-fracture strain in Wingate Sandstone

    NASA Astrophysics Data System (ADS)

    Jamison, William R.

    The Laramide deformation of the Triassic Wingate Sandstone along the northeast flank of the Uncompahgre uplift has occurred by faulting at various scales. Macroscopically smooth flexures of beds within the Wingate occur by small displacements across a myriad of intraformational, mesoscale faults. The deformation resultant from these small faults may be approximated by a strain tensor, provided the measurement domain satisfies certain size criteria. Equivalent strain (ɛ) measurements, obtained from 22 locations in the East Kodel's Canyon, range from 1% to 15.5% (the maximum contractional strains range from -0.9% to -13.4%). The faults producing this strain have displacements ranging from a fraction of a millimeter to 18.5 cm. The fault intensity increases with increasing ɛ, although in a distinctly non-linear fashion. At low strains, incremental increases in the deformation produce additional, small displacement faults. At larger strains, incremental increases in the deformation occur via progressive displacement along existing faults. The principal strain axes are consistently non-coaxial with the inferred principal stresses (average σ1Λɛ1 is 18.5°). This non-coaxiality results from the non-uniform development of the conjugate fault systems. This same inequality of the conjugate systems produces a non-zero rotation tensor, ω, but ω is not related to σ1Λɛ1. The non-uniform development of conjugate shears (and the associated non-coaxiality of σ1 and ɛ1) may be an intrinsic characteristic of a Coulomb material.

  11. Depositional sequence stratigraphy and architecture of the cretaceous ferron sandstone: Implications for coal and coalbed methane resources - A field excursion

    USGS Publications Warehouse

    Garrison, J.R.; Van Den, Bergh; Barker, C.E.; Tabet, D.E.

    1997-01-01

    This Field Excursion will visit outcrops of the fluvial-deltaic Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale, known as the Last Chance delta or Upper Ferron Sandstone. This field guide and the field stops will outline the architecture and depositional sequence stratigraphy of the Upper Ferron Sandstone clastic wedge and explore the stratigraphic positions and compositions of major coal zones. The implications of the architecture and stratigraphy of the Ferron fluvial-deltaic complex for coal and coalbed methane resources will be discussed. Early works suggested that the southwesterly derived deltaic deposits of the the upper Ferron Sandstone clastic wedge were a Type-2 third-order depositional sequence, informally called the Ferron Sequence. These works suggested that the Ferron Sequence is separated by a type-2 sequence boundary from the underlying 3rd-order Hyatti Sequence, which has its sediment source from the northwest. Within the 3rd-order depositional sequence, the deltaic events of the Ferron clastic wedge, recognized as parasequence sets, appear to be stacked into progradational, aggradational, and retrogradational patterns reflecting a generally decreasing sediment supply during an overall slow sea-level rise. The architecture of both near-marine facies and non-marine fluvial facies exhibit well defined trends in response to this decrease in available sediment. Recent studies have concluded that, unless coincident with a depositional sequence boundary, regionally extensive coal zones occur at the tops of the parasequence sets within the Ferron clastic wedge. These coal zones consist of coal seams and their laterally equivalent fissile carbonaceous shales, mudstones, and siltstones, paleosols, and flood plain mudstones. Although the compositions of coal zones vary along depositional dip, the presence of these laterally extensive stratigraphic horizons, above parasequence sets, provides a means of correlating and defining the tops

  12. Petrographic and geochemical analysis of the Givetian-Frasnian sandstones in the Kuh-e-Tizi section, southeastern Central Iran

    NASA Astrophysics Data System (ADS)

    Hejazi, S. H.; Adabi, M. H.; Moussavi Harami, S. R.; Khosro Tehrani, K.

    2009-04-01

    .P., Ramasamy, S., 2004. Geochemistry of sandstones from the Upper Miocene Kudankulam Formation, southern India: implication for provenance, weathering and tectonic setting. J. Sediment. Res. 74, 285-297. Basu, A., Young, S.W., Suttner, L.J., James, W.C., Mack, G.H., 1975. Re-evaluation of the use of undulatory extinction and polycrystallinity in detrital quartz for provenance interpretation. J. Sed. Petrol. 45, 873-882. Bhatia, M.R., 1983. Plate tectonics and geochemical composition of sandstones. J. Geol. 91, 611-627. Bhatia, M.R., Crook, K.A.W., 1986. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins. Contrib. Mineral. Petrol. 92, 181-193. Dickinson, W.R., Beard, L.S., Brakenridge, G.R., Erjavec, J.L., Ferguson, R.C., Inman, K.F., Knepp, R.A., Lindberg, F.A., Ryberg, P.T., 1983. Provenance of North American Phanerozoic sandstones in relation to tectonic setting. Bull. Am. Geol. Soc. 94, 222-235. Kroonenberg, S.B., 1994. Effects of provenance, sorting and weathering on the geochemistry of fluvial sands from different tectonic and climatic environments. Proceedings of the 29th International Geological Congress, Part A, 69-81. Roser, B.P., Korsch, R.J., 1986. Determination of tectonic setting of sandstonemudstone suites using SiO2 content and K2O/Na2O ratio. J. Geol. 94, 635-650. Wendt, J., Kaufmann, B., Belka, Z., Farsan, N. & Karimi bavandpur, A. 2002. Devonian/Lower Carboniferous stratigraphy, facies patterns and palaeogeography of Iran. Part I. Southeastern Iran. Acta Geol. Polo. 52, 129-168.

  13. Sandstone Diagenesis at Gale Crater, Mars, As Observed By Curiosity

    NASA Astrophysics Data System (ADS)

    Siebach, K. L.; Grotzinger, J. P.; McLennan, S. M.; Hurowitz, J.; Kah, L. C.; Edgett, K. S.; Williams, R. M. E.; Wiens, R. C.; Schieber, J.

    2014-12-01

    The Mars Science Laboratory rover, Curiosity, has encountered a significant number of poorly-sorted and very well-lithified sandstones along its traverse on the floor of Gale Crater. We use images from the hand-lens imager (MAHLI) and elemental chemistry from the ChemCam laser-induced breakdown spectroscopy instrument (LIBS) and the alpha-particle x-ray spectrometer (APXS) to begin to constrain the diagenetic history of these sandstones, including lithification and possible later dissolution. Investigation of MAHLI images reveals that the sediments are poorly-sorted and show very low apparent porosity, generally less than ~5%. However, in some cases, such as the Gillespie Lake sandstone identified in Yellowknife Bay, this apparent porosity includes a significant fraction of void spaces larger than typical sediment grain sizes (~30% by number or 75% of void spaces by area). One possible explanation of these larger pits is that they represent recent removal of soft intraclasts by eolian abrasion. Another possibility is that later diagenetic fluids caused dissolution of more soluble grains, and production of secondary porosity. Investigation into the elemental chemistry of the sandstones has shown that they have a relatively unaltered basaltic bulk composition in spite of possessing a variety of secondary minerals and amorphous material, indicating isochemical diagenetic processes. The chemistry and mineralogy of the cement is not immediately evident based on the initial analyses; there is not a high percentage of salts or evaporative minerals that may easily cement near-surface sandstones. Furthermore, these sandstones lack textures and compositions consistent with pedogenic processes, such as calcrete, silcrete, or ferricrete. Instead, they may record burial and cementation at depth. Cement composition may be constrained through comparison to terrestrial basaltic sandstones, and studying chemical variations along ChemCam and APXS transects of the rocks.

  14. Overview: Texas Higher Education Coordinating Board

    ERIC Educational Resources Information Center

    Texas Higher Education Coordinating Board, 2009

    2009-01-01

    The Texas Higher Education Coordinating Board (THECB) was created by the Texas Legislature in 1965 to provide leadership and coordination for the Texas higher education system to achieve excellence for the college education of Texas students. Most of the statutes that are applicable to THECB are found in the Texas Education Code, Title 3, Section…

  15. Geochemistry of Eagle Ford group source rocks and oils from the first shot field area, Texas

    USGS Publications Warehouse

    Edman, Janell D.; Pitman, Janet K.; Hammes, Ursula

    2010-01-01

    Total organic carbon, Rock-Eval pyrolysis, and vitrinite reflectance analyses performed on Eagle Ford Group core and cuttings samples from the First Shot field area, Texas demonstrate these samples have sufficient quantity, quality, and maturity of organic matter to have generated oil. Furthermore, gas chromatography and biomarker analyses performed on Eagle Ford Group oils and source rock extracts as well as weight percent sulfur analyses on the oils indicate the source rock facies for most of the oils are fairly similar. Specifically, these source rock facies vary in lithology from shales to marls, contain elevated levels of sulfur, and were deposited in a marine environment under anoxic conditions. It is these First Shot Eagle Ford source facies that have generated the oils in the First Shot Field. However, in contrast to the generally similar source rock facies and organic matter, maturity varies from early oil window to late oil window in the study area, and these maturity variations have a pronounced effect on both the source rock and oil characteristics. Finally, most of the oils appear to have been generated locally and have not experienced long distance migration. 

  16. Subsurface Glen Rose reef trend in east Texas and west-central Louisiana

    SciTech Connect

    Adams, G.S.

    1983-03-01

    The subsurface Glen Rose reef trend in east Texas and west-central Louisiana (Lower Cretaceous Comanchean) is a regressive carbonate complex deposited on a broad shallow water shelf. The Glen Rose reef trend can be differentiated into two separate reef tracts that prograded seaward over a slowly subsiding shelf. It remains to be seen whether the Glen Rose reefs are actual framework reefs or mounds of transported material. Reef facies include poorly sorted caprinidcoral grainstones, moderately sorted peloid and oncolite packstones and grainstones, and well-sorted, very fine grained skeletal grainstones. Coated grains, abraded skeletal fragments, scoured bedding surfaces, and minor cross-beds are evidence for deposition of the reef facies in a high-energy shoal setting. The reefal buildups grade laterally into low-energy shallow water wackestones and mudstones containing toucasids, orbitolinids, and serpulid burrows. Porosities associated with the reefal buildups appear facies controlled. Caprinid-coral packstones and grainstones exhibit intraparticle, moldic, and vuggy porosities of 10 to 15%. Pinpoint microporosity of 5 to 10% are found within the finegrained skeletal grainstones. Fracture porosity enhances permeability in several facies. Moldic and vuggy porosity types are generally secondary whereas intraparticle porosity may be preserved primary. Coarse equant calcite commonly occludes intraparticle, moldic, vuggy, and fracture porosities. Dolomitization within the reef limestones may have acted t