Science.gov

Sample records for reservoir simulation problems

  1. Experiences with linear solvers for oil reservoir simulation problems

    SciTech Connect

    Joubert, W.; Janardhan, R.; Biswas, D.; Carey, G.

    1996-12-31

    This talk will focus on practical experiences with iterative linear solver algorithms used in conjunction with Amoco Production Company`s Falcon oil reservoir simulation code. The goal of this study is to determine the best linear solver algorithms for these types of problems. The results of numerical experiments will be presented.

  2. Evaluation of linear solvers for oil reservoir simulation problems. Part 2: The fully implicit case

    SciTech Connect

    Joubert, W.; Janardhan, R.

    1997-12-01

    A previous paper [Joubert/Biswas 1997] contained investigations of linear solver performance for matrices arising from Amoco`s Falcon parallel oil reservoir simulation code using the IMPES formulation (implicit pressure, explicit saturation). In this companion paper, similar issues are explored for linear solvers applied to matrices arising from more difficult fully implicit problems. The results of numerical experiments are given.

  3. Geothermal reservoir simulation

    NASA Technical Reports Server (NTRS)

    Mercer, J. W., Jr.; Faust, C.; Pinder, G. F.

    1974-01-01

    The prediction of long-term geothermal reservoir performance and the environmental impact of exploiting this resource are two important problems associated with the utilization of geothermal energy for power production. Our research effort addresses these problems through numerical simulation. Computer codes based on the solution of partial-differential equations using finite-element techniques are being prepared to simulate multiphase energy transport, energy transport in fractured porous reservoirs, well bore phenomena, and subsidence.

  4. Interactive reservoir simulation

    SciTech Connect

    Regtien, J.M.M. Por, G.J.A.; Stiphout, M.T. van; Vlugt, F.F. van der

    1995-12-31

    Shell`s new Modular Reservoir Simulator (MoReS) has been equipped with a comprehensive and versatile user interface called FrontEnd. Apart from providing a user-friendly environment for interactive reservoir simulation, FrontEnd serves a software platform for other dynamic simulation and reservoir-engineering applications. It offers to all supported applications a common user interface, enables the re-use of code and reduces overall maintenance and support costs associated with the embedded applications. Because of its features, FrontEnd facilitates the transfer of research results in the form of operational software to end users. When coupled with MoReS, FrontEnd can be used for pre- and post-processing and interactive simulation. The pre-processing options allow data to be inputted by means of various OSF/Motif widgets containing a spreadsheet, text editors, dialogues and graphical input. The display of the input data as well as the post-processing of all simulation results is made possible by a variety of user-defined plot of tabular (e.g. timestep summary) and array (simulation grid) data. During a simulation user-defined plots can be displayed and edited, allowing a close inspection of the results as they are being calculated. FrontEnd has been equipped with a powerful input command language, which gives the batch user as much flexibility and control over the input as the interactive user.

  5. Models for naturally fractured, carbonate reservoir simulations

    SciTech Connect

    Tuncay, K.; Park, A.; Ozkan, G.; Zhan, X.; Ortoleva, P.; Hoak, T.; Sundberg, K.

    1998-12-31

    This report outlines the need for new tools for the simulation of fractured carbonate reservoirs. Several problems are identified that call for the development of new reservoir simulation physical models and numerical techniques. These include: karst and vuggy media wherein Darcy`s and traditional multi-phase flow laws do not apply; the need for predicting the preproduction state of fracturing and stress so that the later response of effective stress-dependent reservoirs can be predicted; and methods for predicting the fracturing and collapse of vuggy and karst reservoirs in response to draw-down pressure created during production. Specific research directions for addressing each problem are outlined and preliminary results are noted.

  6. Integration of reservoir simulation and geomechanics

    NASA Astrophysics Data System (ADS)

    Zhao, Nan

    Fluid production from tight and shale gas formations has increased significantly, and this unconventional portfolio of low-permeability reservoirs accounts for more than half of the gas produced in the United States. Stimulation and hydraulic fracturing are critical in making these systems productive, and hence it is important to understand the mechanics of the reservoir. When modeling fractured reservoirs using discrete-fracture network representation, the geomechanical effects are expected to have a significant impact on important reservoir characteristics. It has become more accepted that fracture growth, particularly in naturally fractured reservoirs with extremely low permeability, cannot be reliably represented by conventional planar representations. Characterizing the evolution of multiple, nonplanar, interconnected and possibly nonvertical hydraulic fractures requires hydraulic and mechanical characterization of the matrix, as well as existing latent or healed fracture networks. To solve these challenging problems, a reservoir simulator (Advanced Reactive Transport Simulator (ARTS)) capable of performing unconventional reservoir simulation is developed in this research work. A geomechanical model has been incorporated into the simulation framework with various coupling schemes and this model is used to understand the geomechanical effects in unconventional oil and gas recovery. This development allows ARTS to accept geomechanical information from external geomechanical simulators (soft coupling) or the solution of the geomechanical coupled problem (hard coupling). An iterative solution method of the flow and geomechanical equations has been used in implementing the hard coupling scheme. The hard coupling schemes were verified using one-dimensional and two-dimensional analytical solutions. The new reservoir simulator is applied to learn the influence of geomechanical impact on unconventional oil and gas production in a number of practical recovery scenarios

  7. Wavelet based Simulation of Reservoir Flow

    NASA Astrophysics Data System (ADS)

    Siddiqi, A. H.; Verma, A. K.; Noor-E-Zahra, Noor-E.-Zahra; Chandiok, Ashish; Hasan, A.

    2009-07-01

    Petroleum reservoirs consist of hydrocarbons and other chemicals trapped in the pores of a rock. The exploration and production of hydrocarbon reservoirs is still the most important technology to develop natural energy resources. Therefore, fluid flow simulators play a key role in order to help oil companies. In fact, simulation is the most important tool to model changes in a reservoir over the time. The main problem in petroleum reservoir simulation is to model the displacement of one fluid by another within a porous medium. A typical problem is characterized by the injection of a wetting fluid, for example water into the reservoir at a particular location displacing to the non wetting fluid, for example oil, which is extracted or produced at another location. Buckley-Leverett equation [1] models this process and its numerical simulation and visualization is of paramount importance. There are several numerical methods applied for numerical solution of partial differential equations modeling real world problems. We review in this paper the numerical solution of Buckley-Leverett equation for flat and non flat structures with special focus on wavelet method. We also indicate a few new avenues for further research.

  8. Different pressure grids for reservoir simulation in heterogeneous reservoirs

    SciTech Connect

    Guerillot, D.R.; Verdiere, S.

    1995-12-31

    Petroleum reservoirs are made of highly heterogeneous rocks. These reservoirs could be described by geostatistical models composed of millions of cells. Currently, fluid flow simulations performed within these media need upscaling (or averaging) techniques. Hence, their results are given by averaging on cells which are much larger than the geological model cells. To overcome this problem, the Dual Mesh Method is proposed here, whose purpose is to solve the pressure equation on a low resolution grid, and then to interpolate pressure over the fine mesh by taking into account small scale heterogeneities of the mediums. The aim of this paper is the interpolation step; its implementation is presented and illustrated in a five-spot pattern for three different rock characteristics.

  9. Petroleum reservoir data for testing simulation models

    SciTech Connect

    Lloyd, J.M.; Harrison, W.

    1980-09-01

    This report consists of reservoir pressure and production data for 25 petroleum reservoirs. Included are 5 data sets for single-phase (liquid) reservoirs, 1 data set for a single-phase (liquid) reservoir with pressure maintenance, 13 data sets for two-phase (liquid/gas) reservoirs and 6 for two-phase reservoirs with pressure maintenance. Also given are ancillary data for each reservoir that could be of value in the development and validation of simulation models. A bibliography is included that lists the publications from which the data were obtained.

  10. Next generation oil reservoir simulations

    SciTech Connect

    Joubert, W.

    1996-04-01

    This paper describes a collaborative effort between Amoco Production Company, Los Alamos National Laboratory and Cray Research Inc. to develop a next-generation massively parallel oil reservoir simulation code. The simulator, code-named Falcon, enables highly detailed simulations to be performed on a range of platforms such as the Cray T3D and T3E. The code is currently being used by Amoco to perform a sophisticated field study using multiple geostatistical realizations on a scale of 2-5 million grid blocks and 1000-2000 wells. In this paper we discuss the nature of this collaborative effort, the software design and engineering aspects of the code, parallelization experiences, and performance studies. The code will be marketed to the oil industry by a third-party independent software vendor in mid-1996.

  11. Multigrid methods with applications to reservoir simulation

    SciTech Connect

    Xiao, Shengyou

    1994-05-01

    Multigrid methods are studied for solving elliptic partial differential equations. Focus is on parallel multigrid methods and their use for reservoir simulation. Multicolor Fourier analysis is used to analyze the behavior of standard multigrid methods for problems in one and two dimensions. Relation between multicolor and standard Fourier analysis is established. Multiple coarse grid methods for solving model problems in 1 and 2 dimensions are considered; at each coarse grid level we use more than one coarse grid to improve convergence. For a given Dirichlet problem, a related extended problem is first constructed; a purification procedure can be used to obtain Moore-Penrose solutions of the singular systems encountered. For solving anisotropic equations, semicoarsening and line smoothing techniques are used with multiple coarse grid methods to improve convergence. Two-level convergence factors are estimated using multicolor. In the case where each operator has the same stencil on each grid point on one level, exact multilevel convergence factors can be obtained. For solving partial differential equations with discontinuous coefficients, interpolation and restriction operators should include information about the equation coefficients. Matrix-dependent interpolation and restriction operators based on the Schur complement can be used in nonsymmetric cases. A semicoarsening multigrid solver with these operators is used in UTCOMP, a 3-D, multiphase, multicomponent, compositional reservoir simulator. The numerical experiments are carried out on different computing systems. Results indicate that the multigrid methods are promising.

  12. Application of a delumping procedure to compositional reservoir simulations

    SciTech Connect

    Stenby, E.H.; Christensen, J.R.; Knudsen, K.; Leibovici, C.

    1996-12-31

    Characterization and lumping are always performed when dealing with reservoir fluids. The number of pseudocomponents in a compositional reservoir simulation is normally between three and eight. In order to optimize the reservoir performance, it is necessary to know a detailed composition of the product stream from the reservoir. This paper deals with the problems of how to come from the lumped system (for which the reservoir simulation was performed) to a description of the full system (which is important in order to optimize the down-stream facilities). The equations of the delumping procedure are shown and the application of the method is illustrated through examples, including a constant volume depletion experiment and the fifth SPE Comparative example with a fluid description from a North Sea reservoir (with the calculated composition after a lumping, an experiment and a delumping).

  13. Representation of wells in numerical reservoir simulation

    SciTech Connect

    Ding, Y.; Renard, G.; Weill, L.

    1995-12-31

    In reservoir simulation, linear approximations are generally used for well modeling. However, this type of approximations can be inaccurate for fluid flow calculation in the vicinity of wells leading to incorrect well performance predictions. To overcome such problems, a new well representation has been proposed that uses a ``logarithmic`` type of approximation for vertical wells. In this paper, it is shown how the new well model can be easily implemented in existing simulator through the conventional PI. The relationship between wellbore pressure, wellblock pressure and flow rate is discussed in more detail, especially for the definition of wellblock pressure. Extension of the new approach to off-center wells and to flexible grids are both presented. Through this extension, the equivalence of various gridding techniques for the well model is emphasized. The key element is the accurate calculation of flow components in the vicinity of wells.

  14. SMALL, GEOLOGICALLY COMPLEX RESERVOIRS CAN BENEFIT FROM RESERVOIR SIMULATION

    SciTech Connect

    Richard E. Bennett

    2002-06-24

    on, and an expansion of the scope of the reservoir simulation and modeling effort was initiated, using DOE's BOAST98 (a visual, dynamic, interactive update of BOAST3), 3D, black oil reservoir simulation package as the basis for developing the reservoir model. Reservoir characterization, modeling, and reservoir simulation resulted in a significant change in the depletion strategy. Information from the reservoir characterization and modeling effort indicate that in-fill drilling and relying on natural water influx from the aquifer could increase remaining reserves by 125,000 barrels of oil per well, and that up to 10 infill wells could be drilled in the field. Through this scenario, field production could be increased two to three times over the current 65 bopd. Based on the results of the study, permits have been applied for to drill a directional infill well to encounter the productive zone at a high angle in order to maximize the amount of pay and reservoirs encountered.

  15. Large eddy simulation of a pumped- storage reservoir

    NASA Astrophysics Data System (ADS)

    Launay, Marina; Leite Ribeiro, Marcelo; Roman, Federico; Armenio, Vincenzo

    2016-04-01

    The last decades have seen an increasing number of pumped-storage hydropower projects all over the world. Pumped-storage schemes move water between two reservoirs located at different elevations to store energy and to generate electricity following the electricity demand. Thus the reservoirs can be subject to important water level variations occurring at the daily scale. These new cycles leads to changes in the hydraulic behaviour of the reservoirs. Sediment dynamics and sediment budgets are modified, sometimes inducing problems of erosion and deposition within the reservoirs. With the development of computer performances, the use of numerical techniques has become popular for the study of environmental processes. Among numerical techniques, Large Eddy Simulation (LES) has arisen as an alternative tool for problems characterized by complex physics and geometries. This work uses the LES-COAST Code, a LES model under development in the framework of the Seditrans Project, for the simulation of an Upper Alpine Reservoir of a pumped-storage scheme. Simulations consider the filling (pump mode) and emptying (turbine mode) of the reservoir. The hydraulic results give a better understanding of the processes occurring within the reservoir. They are considered for an assessment of the sediment transport processes and of their consequences.

  16. 13. Symposium on reservoir simulation: Proceedings

    SciTech Connect

    1995-12-31

    This is a conference proceedings which deals with the latest developments and trends in reservoir simulation techniques and modeling. It includes papers dealing with multiphase flow in oil and gas wells; flow calculation methods in deviated and horizontal wells; fluid flow in fractured reservoirs; and simulation techniques for enhanced recovery and well stimulation processes. Most papers provide case studies using the various computer models or computer systems, including numerous studies on parallel processing equipment.

  17. An integrated data model for reservoir simulation

    SciTech Connect

    Aydelotte, S.R.

    1994-02-01

    This paper describes the capability of the Epicenter data model to manage reservoir-simulation information, including the spatial model used to describe the properties of the earth and the product-flow network mode used to describe production performance. In addition to data values, the data model describes data creation and quality and provides a reliable means of understanding the source. To use the data model, reservoir-simulation applications need to be rewritten to conform to the data-model nomenclature and conventions. While this is a significant task, the benefit to reservoir simulation practitioners and vendors includes integration of technical applications (such as mapping, well logging, and geophysical interpretation systems), data portability (allowing Vendor A's simulator to use data prepared by Vendor B's preprocessor), and interpretability such as using a third-party optimization package to conduct a series of simulations.

  18. Compositional and black oil reservoir simulation

    SciTech Connect

    Coats, K.H.; Thomas, L.K.; Pierson, R.G.

    1995-12-31

    This paper describes a three-dimensional, three-phase reservoir simulation model for black oil and compositional applications. Both IMPES and fully implicit formulations are included. The model`s use of a relaxed volume balance concept effectively conserves both mass and volume and reduces Newton iterations. A new implicit well rate calculation method improves IMPES stability. It approximates wellbore crossflow effects with high efficiency and relative simplicity in both IMPES and fully implicit formulations. Multiphase flow in the tubing and near-well turbulent gas flow effects are treated implicitly. Initial saturations are calculated as a function of water-oil and gas-oil capillary pressures which are optimally dependent upon the Leverett J function or initial saturations may be entered as data arrays. A normalization of the relative permeability and capillary pressure curves is used to calculate these terms as a function of rock type and grid block residual saturations. Example problems are presented, including several of the SPE Comparative Solution problems and field simulations. 48 refs.

  19. A general formulation for compositional reservoir simulation

    SciTech Connect

    Rodriguez, F.; Guzman, J.; Galindo-Nava, A. |

    1994-12-31

    In this paper the authors present a general formulation to solve the non-linear difference equations that arise in compositional reservoir simulation. The general approach here presented is based on newton`s method and provides a systematic approach to generate several formulations to solve the compositional problem, each possessing a different degree of implicitness and stability characteristics. The Fully-Implicit method is at the higher end of the implicitness spectrum while the IMPECS method, implicit in pressure-explicit in composition and saturation, is at the lower end. They show that all methods may be obtained as particular cases of the fully-implicit method. Regarding the matrix problem, all methods have a similar matrix structure; the composition of the Jacobian matrix is however unique in each case, being in some instances amenable to reductions for optimal solution of the matrix problem. Based on this, a different approach to derive IMPECS type methods is proposed; in this case, the whole set of 2nc + 6 equations, that apply in each gridblock, is reduced to a single pressure equation through matrix reduction operations; this provides a more stable numerical scheme, compared to other published IMPCS methods, in which the subset of thermodynamic equilibrium equations is arbitrarily decoupled form the set of gridblock equations to perform such reduction. The authors discuss how the general formulation here presented can be used to formulate and construct an adaptive-implicit compositional simulators. They also present results on the numerical performance of FI, IMPSEC and IMPECS methods on some test problems.

  20. Massachusetts reservoir simulation tool—User’s manual

    USGS Publications Warehouse

    Levin, Sara B.

    2016-10-06

    IntroductionThe U.S. Geological Survey developed the Massachusetts Reservoir Simulation Tool to examine the effects of reservoirs on natural streamflows in Massachusetts by simulating the daily water balance of reservoirs. The simulation tool was developed to assist environmental managers to better manage water withdrawals in reservoirs and to preserve downstream aquatic habitats.

  1. Petroleum reservoir simulation in a virtual environment

    SciTech Connect

    Jacobsen, J.S.; Bethel, E.W.; Datta-Gupta, A.; Holland, P.J.

    1995-12-31

    In this paper, the authors describe an approach to combining a reservoir simulation with 3-D visualization and virtual reality technology. Their prototype VR/visualization system minimizes human-machine interface barriers and provides enhanced control over the simulation, thereby maximizing scientific judgment and use of intuition. They illustrate the practical advantage of using the VR/visualization prototype system in reservoir engineering by visualizing the results of a waterflood in an oil field with a three-dimensional, spatially correlated heterogeneous permeability field.

  2. Hybrid-CVFE method for flexible-grid reservoir simulation

    SciTech Connect

    Fung, L.S.K.; Buchanan, L.; Sharma, R. )

    1994-08-01

    Well flows and pressures are the most important boundary conditions in reservoir simulation. In a typical simulation, rapid changes and large pressure, temperature, saturation, and composition gradients occur in near-well regions. Treatment of these near-well phenomena significantly affects the accuracy of reservoir simulation results; therefore, extensive efforts have been devoted to the numerical treatment of wells and near-well flows. The flexible control-volume finite-element (CVFE) method is used to construct hybrid grids. The method involves use of a local cylindrical or elliptical grid to represent near-well flow accurately while honoring complex reservoir boundaries. The grid transition is smooth without any special discretization approximation, which eliminates the grid transition problem experienced with Cartesian local grid refinement and hybrid Cartesian gridding techniques.

  3. Evolution of analyzing reservoir simulation data

    SciTech Connect

    Phelps, R.E.; Huang, A.Y.

    1994-12-31

    Numerical Reservoir Simulation is routinely used by the petroleum producing companies world-wide as an engineering tool to efficiently manage their hydrocarbon reservoirs. The task of building models with a large number of grid-blocks is not easy, and to analyze the voluminous results produced by such models is even more difficult. This paper discusses the historical evolution of techniques used to analyze reservoir simulation data over the past decade. It outlines how the advancement of workstation technology and the introduction of X-Window System opened up an entirely new way of utilizing mainframe computing power and workstation graphical display capabilities, simultaneously. The paper also discusses Saudi Aramco`s experience in the development of sophisticated reservoir simulation post-processing packages. The need for direct communication between the programmer and end-users to facilitate a user-friendly package is emphasized. A practical example illustrating the benefit of these post-processing packages in the construction and history matching of a large model with approximately 52,000 cells is presented. Savings in manpower and computer resources using current technology are estimated.

  4. Evolution of analyzing reservoir simulation data

    SciTech Connect

    Phelps, R.E.; Huang, A.Y.

    1995-12-01

    Petroleum-producing companies world-wide routinely use numerical reservoir simulation as an engineering tool to manage their hydrocarbon reservoirs efficiently. The task of building models with a large number of gridblocks is not easy, and analyzing the voluminous results produced by such models is even more difficult. This paper discusses the historical evolution of techniques used to analyze reservoir simulation data over the past decade. It outlines how the advancement of workstation technology and the introduction of an X-Window system opened up an entirely new way of using mainframe computing power and workstation graphical display capabilities simultaneously. The paper also discusses Saudi Aramco`s experience in the development of sophisticated reservoir simulation postprocessing packages. The authors emphasize the need for direct communication between the programmer and end users to facilitate a user-friendly package. They present a practical example illustrating the benefit of these postprocessing packages in the construction and history matching of a large model with approximately 52,000 cells. They estimate savings in manpower and computer resources using current technology.

  5. Geomechanically Coupled Simulation of Flow in Fractured Reservoirs

    NASA Astrophysics Data System (ADS)

    Barton, C.; Moos, D.; Hartley, L.; Baxter, S.; Foulquier, L.; Holl, H.; Hogarth, R.

    2012-12-01

    Capturing the necessary and sufficient detail of reservoir hydraulics to accurately evaluate reservoir behavior remains a significant challenge to the exploitation and management of fracture-dominated geothermal reservoirs. In these low matrix permeability reservoirs, stimulation response is controlled largely by the properties of natural and induced fracture networks, which are in turn controlled by the in situ stresses, the fracture distribution and connectivity and the hydraulic behavior of the fractures. This complex interaction of fracture flow systems with the present-day stress field compounds the problem of developing an effective and efficient simulation to characterize, model and predict fractured reservoir performance. We discuss here a case study of the integration of geological, geophysical, geomechanical, and reservoir engineering data to characterize the in situ stresses, the natural fracture network and the controls on fracture permeability in geothermal reservoirs. A 3D geomechanical reservoir model includes constraints on stress magnitudes and orientations, and constraints on mechanical rock properties and the fractures themselves. Such a model is essential to understanding reservoir response to stimulation and production in low matrix permeability, fracture-dominated reservoirs. The geomechanical model for this study was developed using petrophysical, drilling, and wellbore image data along with direct well test measurements and was mapped to a 3D structural grid to facilitate coupled simulation of the fractured reservoir. Wellbore image and stimulation test data were used along with microseismic data acquired during the test to determine the reservoir fracture architecture and to provide control points for a realistic inter-connected discrete fracture network. As most fractures are stress-sensitive, their hydraulic conductivities will change with changes in bottomhole flowing and reservoir pressures, causing variations in production profiles

  6. Rabi multi-sector reservoir simulation model

    SciTech Connect

    Bruijnzeels, C.; O`Halloran, C.

    1995-12-31

    To ensure optimum ultimate recovery of the 46 meter thick oil rim of the Rabi Field in Gabon, a full field simulation model was required. Due to it`s size and complexity, with local cusping, coning and geological circumstances dominating individual well behavior, a single full field model would be too large for existing hardware. A method was developed to simulate the full field with 5 separate sector models, whilst allowing the development in one sector model to have an effect on the boundary conditions of another sector. In this manner, the 13 x 4.5 km field could be simulated with a horizontal well spacing down to 175 meter. This paper focuses on the method used to attach single 3-phase tank cells to a sector simulation grid in order to represent non-simulated parts of the field. It also describes the history matching methodology and how to run a multisector model in forecasting mode. This method can be used for any reservoir, where size and complexity require large reservoir simulation models that normally could not be modeled within the constraints of available computer facilities. Detailed studies can be conducted on specific parts of a field, whilst allowing for dynamic flow and pressure effects caused by the rest of the field.

  7. Compositional reservoir simulation in parallel supercomputing environments

    SciTech Connect

    Briens, F.J.L. ); Wu, C.H. ); Gazdag, J.; Wang, H.H. )

    1991-09-01

    A large-scale compositional reservoir simulation ({gt}1,000 cells) is not often run on a conventional mainframe computer owing to excessive turnaround times. This paper presents programming and computational techniques that fully exploit the capabilities of parallel supercomputers for a large-scale compositional simulation. A novel algorithm called sequential staging of tasks (SST) that can take full advantage of parallel-vector processing to speed up the solution of a large linear system is introduced. The effectiveness of SST is illustrated with results from computer experiments conducted on an IBM 3090-600E.

  8. Comparison of flash calculations in compositional reservoir simulation

    SciTech Connect

    Wang, P.; Barker, J.W.

    1995-12-31

    This paper compares several recent flash algorithms in the context of compositional reservoir simulation. We evaluate three reduced equation methods: (1) the 3-equation flash of Michelsen, which applies only when all binary interaction coefficients (k{sub ij}) are zero; (2) Hendricks and van Bergen; and (3) Kaul and Thrasher. We also evaluate; (4) the non-iterative flash; and (5) the method of Young. We find that these last two methods, which are similar in concept, work well for reservoir simulation where the flash must be closely coupled with the solution of the pressure equation, and where a good initial guess is generally available. The reduced equation flashes offer no significant improvement over these other methods; this is true even for the 3-equation flash which solves a simpler problem (with k{sub ij} = 0).

  9. Iterative Schemes for Time Parallelization with Application to Reservoir Simulation

    SciTech Connect

    Garrido, I; Fladmark, G E; Espedal, M S; Lee, B

    2005-04-18

    Parallel methods are usually not applied to the time domain because of the inherit sequentialness of time evolution. But for many evolutionary problems, computer simulation can benefit substantially from time parallelization methods. In this paper, they present several such algorithms that actually exploit the sequential nature of time evolution through a predictor-corrector procedure. This sequentialness ensures convergence of a parallel predictor-corrector scheme within a fixed number of iterations. The performance of these novel algorithms, which are derived from the classical alternating Schwarz method, are illustrated through several numerical examples using the reservoir simulator Athena.

  10. Performance prediction using geostatistics and window reservoir simulation

    SciTech Connect

    Fontanilla, J.P.; Al-Khalawi, A.A.; Johnson, S.G.

    1995-11-01

    This paper is the first window model study in the northern area of a large carbonate reservoir in Saudi Arabia. It describes window reservoir simulation with geostatistics to model uneven water encroachment in the southwest producing area of the northern portion of the reservoir. In addition, this paper describes performance predictions that investigate the sweep efficiency of the current peripheral waterflood. A 50 x 50 x 549 (240 m. x 260 m. x 0.15 m. average grid block size) geological model was constructed with geostatistics software. Conditional simulation was used to obtain spatial distributions of porosity and volume of dolomite. Core data transforms were used to obtain horizontal and vertical permeability distributions. Simple averaging techniques were used to convert the 549-layer geological model to a 50 x 50 x 10 (240 m. x 260 m. x 8 m. average grid block size) window reservoir simulation model. Flux injectors and flux producers were assigned to the outermost grid blocks. Historical boundary flux rates were obtained from a coarsely-ridded full-field model. Pressure distribution, water cuts, GORs, and recent flowmeter data were history matched. Permeability correction factors and numerous parameter adjustments were required to obtain the final history match. The permeability correction factors were based on pressure transient permeability-thickness analyses. The prediction phase of the study evaluated the effects of infill drilling, the use of artificial lifts, workovers, horizontal wells, producing rate constraints, and tight zone development to formulate depletion strategies for the development of this area. The window model will also be used to investigate day-to-day reservoir management problems in this area.

  11. Activity of sulfate-reducing bacteria under simulated reservoir conditions

    SciTech Connect

    Rosnes, J.T.; Graue, A.; Lien, T. )

    1991-05-01

    This paper reports on sulfate-reducing bacteria (SRB) that have been isolated from hot oilfield waters from subsea oil reservoirs in the North Sea. Experiments with these bacteria in a reservoir simulator indicate that SRB may maintain their activity in the conditions found in most North Sea reservoirs and, if precautions are not taken, may contribute to souring of the oil and gas.

  12. Multi-Purpose, Multi-Reservoir Simulation on a PC

    DTIC Science & Technology

    1988-08-01

    The methodology and difficulties in converting a large, general purpose, mainframe, batch oriented computer program (for reservoir simulation ) to...work effectively in the PC environment are described in this paper. A brief overview of the present capabilities of the general purpose reservoir ... simulation program (HEC-5), that works on mainframe and MS DOS compatible computers, is also presented. Keywords: Simulation, Personal computer, Reservior

  13. ADVANCED TECHNIQUES FOR RESERVOIR SIMULATION AND MODELING OF NONCONVENTIONAL WELLS

    SciTech Connect

    Louis J. Durlofsky; Khalid Aziz

    2004-08-20

    Nonconventional wells, which include horizontal, deviated, multilateral and ''smart'' wells, offer great potential for the efficient management of oil and gas reservoirs. These wells are able to contact larger regions of the reservoir than conventional wells and can also be used to target isolated hydrocarbon accumulations. The use of nonconventional wells instrumented with downhole inflow control devices allows for even greater flexibility in production. Because nonconventional wells can be very expensive to drill, complete and instrument, it is important to be able to optimize their deployment, which requires the accurate prediction of their performance. However, predictions of nonconventional well performance are often inaccurate. This is likely due to inadequacies in some of the reservoir engineering and reservoir simulation tools used to model and optimize nonconventional well performance. A number of new issues arise in the modeling and optimization of nonconventional wells. For example, the optimal use of downhole inflow control devices has not been addressed for practical problems. In addition, the impact of geological and engineering uncertainty (e.g., valve reliability) has not been previously considered. In order to model and optimize nonconventional wells in different settings, it is essential that the tools be implemented into a general reservoir simulator. This simulator must be sufficiently general and robust and must in addition be linked to a sophisticated well model. Our research under this five year project addressed all of the key areas indicated above. The overall project was divided into three main categories: (1) advanced reservoir simulation techniques for modeling nonconventional wells; (2) improved techniques for computing well productivity (for use in reservoir engineering calculations) and for coupling the well to the simulator (which includes the accurate calculation of well index and the modeling of multiphase flow in the wellbore

  14. Suitable Conditions of Reservoir Simulation for Searching Rule Curves

    NASA Astrophysics Data System (ADS)

    Kangrang, Anongrit; Chaleeraktrakoon, Chavalit

    The objective of this study is to carry out a suitable length of inflow record using in the simulation model. The second objective is to find an effect of initial reservoir capacity of reservoir simulation for searching the optimal rule curves. The reservoir simulation model was connected with genetic algorithms to search the optimal rule curves quickly. The model has been applied to determine the optimal rule curves of the Bhumibol and Sirikit Reservoirs (the Chao Phraya River Basin, Thailand). The optimal rule curves of each condition were used to assess by a Monte Carlo simulation. The results show that the shortest period of dry inflow record using in the simulation model in order to search the optimal rule curves is 10 year. Furthermore, the minimum initial capacity of reservoir for searching optimal rule curves is 10% of full capacity.

  15. Feasibility study of sedimentary enhanced geothermal systems using reservoir simulation

    NASA Astrophysics Data System (ADS)

    Cho, Jae Kyoung

    The objective of this research is to evaluate the preliminary feasibility of commercial geothermal projects, from a sedimentary reservoir with low permeability that requires productivity enhancement, using numerical reservoir simulation. The performance of a sedimentary geothermal reservoir is investigated in terms of reservoir hydraulics and thermal evolution. To build a reliable benchmark for simulation study, validation of the numerical reservoir model with respect to an analytical model is presented, and the process to achieve an acceptable match between the numerical and analytical solutions is described. The analytical model used in this study is based on the work of Gringarten (1978), which consists of a conceptual geothermal reservoir, considering an injection and production well doublet in a homogeneous porous media. A commercial thermal reservoir simulator (STARS from Computer Modeling Group, CMG) is used in this work for numerical modeling. In order to reproduce the analytical model results, the numerical simulation model is modified to include the same assumptions of the analytical model. Simulation model parameters that make the numerical results deviate from the analytical solution, such as the grid block size, time step and no-flow boundary are identified and investigated. An analytical tracer test model proposed by Shook (2000) is numerically modeled. This model allows us to predict the time when the temperature of the produced water decreases by capturing a tracer component at production well. Reservoir simulation models with different porosity and permeability distribution are tested to see the effects of reservoir inhomogeneity and anisotropy. In particular, premature thermal breakthrough due to the presence of high permeability streak in a reservoir model is simulated. In an effort to apply the knowledge we obtained from the analytical solutions, the effects of reservoir rock and water properties, as a function of pressure and temperature, are

  16. Cooperative Learning in Reservoir Simulation Classes: Overcoming Disparate Entry Skills

    ERIC Educational Resources Information Center

    Awang, Mariyamni

    2006-01-01

    Reservoir simulation is one of the core courses in the petroleum engineering curriculum and it requires knowledge and skills in three major disciplines, namely programming, numerical methods and reservoir engineering. However, there were often gaps in the students' readiness to undertake the course, even after completing the necessary…

  17. Estimation of discontinuous coefficients in parabolic systems: Applications to reservoir simulation

    NASA Technical Reports Server (NTRS)

    Lamm, P. D.

    1984-01-01

    Spline based techniques for estimating spatially varying parameters that appear in parabolic distributed systems (typical of those found in reservoir simulation problems) are presented. The problem of determining discontinuous coefficients, estimating both the functional shape and points of discontinuity for such parameters is discussed. Convergence results and a summary of numerical performance of the resulting algorithms are given.

  18. Identification and quantification of fracture behavior through reservoir simulation

    SciTech Connect

    Cline, S. |

    1995-08-01

    This study demonstrated the use of reservoir simulation as a tool for quantifying and describing the relative significance of fracture and matrix flow units to overall reservoir storage capacity and transmissibility in a field development example. A high matrix porosity Pennsylvanian age sandstone oil reservoir, that is currently undergoing the early stages of secondary recovery by waterflood, was studied. Unexpected early water breakthrough indicated the presence of a high directional permeability fracture system superimposed on the high porosity matrix system. To further understand the reservoir behavior, improve field performance and to quantify the relative contributions of fracture and matrix units to permeability and storage capacity, a reservoir simulation and characterization project was initiated. Well test, well log, tracer and geologic data were integrated into the simulation project. The integrated study indicated that the fractures exhibited high directional permeability but low storage capacity relative to the matrix portion of the reservoir. Although fractures heavily influenced overall fluid flow behavior, they did not contain large storage capacity. The system had a low calculated fracture intensity index. Reservoir simulation enabled the quantification of the relative importance of the two flow systems which in turn had a large impact on total reserves estimates and production forecasting. Simulation results indicated a need to realign injector and producer patterns which improved production rates and ultimate recovery.

  19. Fractal distributions of reservoir properties and their use in reservoir simulation

    SciTech Connect

    Berta, D.; Hardy, H.H.; Beier, R.A.

    1994-12-31

    Geostatistics has become a popular way to distribute reservoir properties between wells. One of the geostatistical methods being used is fractal geostatistics. Most porosity well logs have been found to have a fractal character. An analysis of vertical and horizontal logs, core photos, and outcrop photos has led to a rather simple model to describe porosity and permeability distributions. This representation has been tested in reservoir simulation of a mature waterflood and found to match production history with very little history matching. Fractal distributions were found to require much less history matching than classical layer cake models. Conoco is now actively applying this new technology to a number of its reservoirs.

  20. Coupling geostatistics to detailed reservoir description allows better visualization and more accurate characterization/simulation of turbidite reservoirs: Elk Hills oil field, California

    SciTech Connect

    Allan, M.E.; Wilson, M.L.; Wightman, J. )

    1996-01-01

    The Elk Hills giant oilfield, located in the southern San Joaquin Valley of California, has produced 1.1 billion barrels of oil from Miocene and shallow Pliocene reservoirs. 65% of the current 64,000 BOPD production is from the pressure-supported, deeper Miocene turbidite sands. In the turbidite sands of the 31 S structure, large porosity permeability variations in the Main Body B and Western 31 S sands cause problems with the efficiency of the waterflooding. These variations have now been quantified and visualized using geostatistics. The end result is a more detailed reservoir characterization for simulation. Traditional reservoir descriptions based on marker correlations, cross-sections and mapping do not provide enough detail to capture the short-scale stratigraphic heterogeneity needed for adequate reservoir simulation. These deterministic descriptions are inadequate to tie with production data as the thinly bedded sand/shale sequences blur into a falsely homogenous picture. By studying the variability of the geologic petrophysical data vertically within each wellbore and spatially from well to well, a geostatistical reservoir description has been developed. It captures the natural variability of the sands and shales that was lacking from earlier work. These geostatistical studies allow the geologic and petrophysical characteristics to be considered in a probabilistic model. The end-product is a reservoir description that captures the variability of the reservoir sequences and can be used as a more realistic starting point for history matching and reservoir simulation.

  1. Coupling geostatistics to detailed reservoir description allows better visualization and more accurate characterization/simulation of turbidite reservoirs: Elk Hills oil field, California

    SciTech Connect

    Allan, M.E.; Wilson, M.L.; Wightman, J.

    1996-12-31

    The Elk Hills giant oilfield, located in the southern San Joaquin Valley of California, has produced 1.1 billion barrels of oil from Miocene and shallow Pliocene reservoirs. 65% of the current 64,000 BOPD production is from the pressure-supported, deeper Miocene turbidite sands. In the turbidite sands of the 31 S structure, large porosity & permeability variations in the Main Body B and Western 31 S sands cause problems with the efficiency of the waterflooding. These variations have now been quantified and visualized using geostatistics. The end result is a more detailed reservoir characterization for simulation. Traditional reservoir descriptions based on marker correlations, cross-sections and mapping do not provide enough detail to capture the short-scale stratigraphic heterogeneity needed for adequate reservoir simulation. These deterministic descriptions are inadequate to tie with production data as the thinly bedded sand/shale sequences blur into a falsely homogenous picture. By studying the variability of the geologic & petrophysical data vertically within each wellbore and spatially from well to well, a geostatistical reservoir description has been developed. It captures the natural variability of the sands and shales that was lacking from earlier work. These geostatistical studies allow the geologic and petrophysical characteristics to be considered in a probabilistic model. The end-product is a reservoir description that captures the variability of the reservoir sequences and can be used as a more realistic starting point for history matching and reservoir simulation.

  2. Hydrodynamic modeling of petroleum reservoirs using simulator MUFITS

    NASA Astrophysics Data System (ADS)

    Afanasyev, Andrey

    2015-04-01

    MUFITS is new noncommercial software for numerical modeling of subsurface processes in various applications (www.mufits.imec.msu.ru). To this point, the simulator was used for modeling nonisothermal flows in geothermal reservoirs and for modeling underground carbon dioxide storage. In this work, we present recent extension of the code to petroleum reservoirs. The simulator can be applied in conventional black oil modeling, but it also utilizes a more complicated models for volatile oil and gas condensate reservoirs as well as for oil rim fields. We give a brief overview of the code by providing the description of internal representation of reservoir models, which are constructed of grid blocks, interfaces, stock tanks as well as of pipe segments and pipe junctions for modeling wells and surface networks. For conventional black oil approach, we present the simulation results for SPE comparative tests. We propose an accelerated compositional modeling method for sub- and supercritical flows subjected to various phase equilibria, particularly to three-phase equilibria of vapour-liquid-liquid type. The method is based on the calculation of the thermodynamic potential of reservoir fluid as a function of pressure, total enthalpy and total composition and storing its values as a spline table, which is used in hydrodynamic simulation for accelerated PVT properties prediction. We provide the description of both the spline calculation procedure and the flashing algorithm. We evaluate the thermodynamic potential for a mixture of two pseudo-components modeling the heavy and light hydrocarbon fractions. We develop a technique for converting black oil PVT tables to the potential, which can be used for in-situ hydrocarbons multiphase equilibria prediction under sub- and supercritical conditions, particularly, in gas condensate and volatile oil reservoirs. We simulate recovery from a reservoir subject to near-critical initial conditions for hydrocarbon mixture. We acknowledge

  3. A chemical EOR benchmark study of different reservoir simulators

    NASA Astrophysics Data System (ADS)

    Goudarzi, Ali; Delshad, Mojdeh; Sepehrnoori, Kamy

    2016-09-01

    Interest in chemical EOR processes has intensified in recent years due to the advancements in chemical formulations and injection techniques. Injecting Polymer (P), surfactant/polymer (SP), and alkaline/surfactant/polymer (ASP) are techniques for improving sweep and displacement efficiencies with the aim of improving oil production in both secondary and tertiary floods. There has been great interest in chemical flooding recently for different challenging situations. These include high temperature reservoirs, formations with extreme salinity and hardness, naturally fractured carbonates, and sandstone reservoirs with heavy and viscous crude oils. More oil reservoirs are reaching maturity where secondary polymer floods and tertiary surfactant methods have become increasingly important. This significance has added to the industry's interest in using reservoir simulators as tools for reservoir evaluation and management to minimize costs and increase the process efficiency. Reservoir simulators with special features are needed to represent coupled chemical and physical processes present in chemical EOR processes. The simulators need to be first validated against well controlled lab and pilot scale experiments to reliably predict the full field implementations. The available data from laboratory scale include 1) phase behavior and rheological data; and 2) results of secondary and tertiary coreflood experiments for P, SP, and ASP floods under reservoir conditions, i.e. chemical retentions, pressure drop, and oil recovery. Data collected from corefloods are used as benchmark tests comparing numerical reservoir simulators with chemical EOR modeling capabilities such as STARS of CMG, ECLIPSE-100 of Schlumberger, REVEAL of Petroleum Experts. The research UTCHEM simulator from The University of Texas at Austin is also included since it has been the benchmark for chemical flooding simulation for over 25 years. The results of this benchmark comparison will be utilized to improve

  4. A CUDA based parallel multi-phase oil reservoir simulator

    NASA Astrophysics Data System (ADS)

    Zaza, Ayham; Awotunde, Abeeb A.; Fairag, Faisal A.; Al-Mouhamed, Mayez A.

    2016-09-01

    Forward Reservoir Simulation (FRS) is a challenging process that models fluid flow and mass transfer in porous media to draw conclusions about the behavior of certain flow variables and well responses. Besides the operational cost associated with matrix assembly, FRS repeatedly solves huge and computationally expensive sparse, ill-conditioned and unsymmetrical linear system. Moreover, as the computation for practical reservoir dimensions lasts for long times, speeding up the process by taking advantage of parallel platforms is indispensable. By considering the state of art advances in massively parallel computing and the accompanying parallel architecture, this work aims primarily at developing a CUDA-based parallel simulator for oil reservoir. In addition to the initial reported 33 times speed gain compared to the serial version, running experiments showed that BiCGSTAB is a stable and fast solver which could be incorporated in such simulations instead of the more expensive, storage demanding and usually utilized GMRES.

  5. Reservoir simulation of a high viscous crude and strong water drive reservoir in Sarawak, Malaysia

    SciTech Connect

    Ramli, A.

    1995-10-01

    The Bokor field is located offshore Sarawak, Malaysia and is one of the largest fields in the Baram Delta Province. The A3/6 group of reservoirs is the largest among the Bokor reservoir groups. The reservoir comprises a series of multiple, stacked, well-developed, fluviomarine sandstones connected to a large aquifer. Production from this reservoir started in 1983 and since then some 15 MMstb of oil have been produced. To better understand the production performance, displacement mechanism and further development opportunities in this high viscous crude (10 cP) and strong water drive reservoir, a 3D sector reservoir simulation has been carried out. The model comprises 8640 active grid blocks, with 14 strings completed on four reservoir units with separate fluid contacts. The layering system and grid dimensions were found to be critical in the history matching process, which was supported by a X-sectional study carried out prior to embarking on the 3D model. Based on the history match, remaining oil was identified on the eastern flank, at the top of each sand unit (due to water under-running) and in the downdip area due to the existing crestal oriented development. The history matched model was subsequently used to aid further development planning and to formulate a cost-effective reservoir management strategy. Various development scenarios were tested in this 3D model, which include infill drilling, horizontal wells and pressure maintenance by water injection. This paper describes the various steps taken to obtain a good history match over the 10 years of production history and discusses the findings of the prediction runs.

  6. Multimodal reservoir porosity simulation: An application to a tight oil reservoir

    NASA Astrophysics Data System (ADS)

    Sauvageau, Mathieu; Gloaguen, Erwan; Claprood, Maxime; Lefebvre, René; Bêche, Martin

    2014-08-01

    At appraisal stage of a reservoir characterization, a key step is the inference of the reservoir static properties, such as porosity. In this study, we present a new nested workflow that optimally integrates 3D acoustic impedance and geophysical log data for the estimation of the spatial distribution of reservoir porosity, which is applied to a tight sandstone oil reservoir located in Quebec, Canada. In this workflow, 3D seismic is the main source of spatial information. First, the statistical petrophysical relationship between acoustic impedance and reservoir porosity is established using collocated geophysical log data. Second, a conventional least-squares post-stack inversion of the impedance is computed on the seismic grid. The fit between well log data and numerically computed traces was found to be inaccurate. This leads to the third step, involving a post-stack stochastic impedance inversion using the same seismic traces not only to improve well and trace fit but also to estimate the uncertainty on the inverted impedances. Finally, a Bayesian simulation algorithm adapted to the estimation of a multi-modal porosity distribution is used to simulate realizations of porosity over the entire seismic grid. Results show that the over-smoothing effect of least-squares inversion has a major impact on resource evaluation, especially by not reproducing the high-valued tail of the porosity distribution. The adapted Bayesian algorithm combined with stochastic impedance inversion thus allows a better reproduction of the porosity distribution and improves estimation of the geophysical and geological uncertainty.

  7. Large-scale three-dimensional geothermal reservoir simulation on PCs

    SciTech Connect

    Antunez, Emilio; Moridis, George; Pruess, Karsten

    1994-01-20

    TOUGH2, Lawrence Berkeley Laboratory's general purpose simulator for mass and heat flow and transport was enhanced with the addition of a set of preconditioned conjugate gradient solvers and ported to a PC. The code was applied to a number of large 3-D geothermal reservoir problems with up to 10,000 grid blocks. Four test problems were investigated. The first two involved a single-phase liquid system, and a two-phase system with regular Cartesian grids. The last two involved a two-phase field problem with irregular gridding with production from and injection into a single porosity reservoir, and a fractured reservoir. The code modifications to TOUGH2 and its setup in the PC environment are described. Algorithms suitable for solving large matrices that are generally non-symmetric and non-positive definite are reviewed. Computational work per time step and CPU time requirements are reported as function of problem size. The excessive execution time and storage requirements of the direct solver in TOUGH2 limits the size of manageable 3-D reservoir problems to a few hundred grid blocks. The conjugate gradient solvers significantly reduced the execution time and storage requirements making possible the execution of considerably larger problems (10,000+ grid blocks). It is concluded that the current PCs provide an economical platform for running large-scale geothermal field simulations that just a few years ago could only be executed on mainframe computers.

  8. Large-scale three-dimensional geothermal reservoir simulation on PCs

    SciTech Connect

    Antunez, E.; Moridis, G.; Pruess, K.

    1994-01-01

    TOUGH2, Lawrence Berkeley Laboratory`s general purpose simulator for mass and heat flow and transport was enhanced with the addition of a set of preconditioned conjugate gradient solvers and ported to a PC. The code was applied to a number of large 3-D geothermal reservoir problems with up to 10,000 grid blocks. Four test problems were investigated. The first two involved a single-phase liquid system, and a two-phase system with regular Cartesian grids. The last two involved a two-phase field problem with irregular gridding with production from and injection into a single porosity reservoir, and a fractured reservoir. The code modifications to TOUGH2 and its setup in the PC environment are described. Algorithms suitable for solving large matrices that are generally non-symmetric and non-positive definite are reviewed. Computational work per time step and CPU time requirements are reported as function of problem size. The excessive execution time and storage requirements of the direct solver in TOUGH2 limits the size of manageable 3-D reservoir problems to a few hundred grid blocks. The conjugate gradient solvers significantly reduced the execution time and storage requirements making possible the execution of considerably larger problems (10,000 + grid blocks). It is concluded that the current PCs provide an economical platform for running large-scale geothermal field simulations that just a few years ago could only be executed on mainframe computers.

  9. Marine radiocarbon reservoir age simulations for the past 50000 years

    NASA Astrophysics Data System (ADS)

    Butzin, Martin; Köhler, Peter; Lohmann, Gerrit

    2016-04-01

    We present simulations of marine radiocarbon reservoir ages using the ocean general circulation model LSG-HAMOCC2s, and evaluate the results with Marine13 raw data records. Our model considers various climatic background states. Radiocarbon cycle boundary conditions are atmospheric Δ14C values according to IntCal13, a recent atmospheric CO2 reconstruction, and spatially variable concentrations of dissolved inorganic carbon derived from marine carbon cycle simulations. Our model reasonably agrees with glacial marine Δ14C records but indicates reservoir ages varying with time, different to the invariant reservoir age corrections applied to the observations and to Marine13. Modelled global-mean reservoir ages are in the range 400-800 years compared to the invariant Marine13 value of 405 years. Self-consistent simulations involving the Cariaco Basin record (which is the most continuous marine record contributing to IntCal13 for periods prior to about 30 kyears) amplify the temporal reservoir age variability with global-mean values of about 350-850 years, and improve the agreement with Δ14C observations in some areas.

  10. Application of advanced reservoir characterization, simulation, and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, West Texas (Delaware Basin). Technical progress report

    SciTech Connect

    Dutton, S.P.

    1996-04-30

    The objective of this project is to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. Project objectives are divided into two major phases. The objectives of the reservoir characterization phase of the project are to provide a detailed understanding of the architecture and heterogeneity of two fields, the Ford Geraldine unit and Ford West field, which produce from the Bell Canyon and Cherry Canyon Formations, respectively, of the Delaware Mountain Group and to compare Bell Canyon and Cherry Canyon reservoirs. Reservoir characterization will utilize 3-D seismic data, high-resolution sequence stratigraphy, subsurface field studies, outcrop characterization, and other techniques. One the reservoir-characterization study of both field is completed, a pilot area of approximately 1 mi{sup 2} in one of the fields will be chosen for reservoir simulation. The objectives of the implementation phase of the project are to: (1) apply the knowledge gained from reservoir characterization and simulation studies to increase recovery from the pilot area; (2) demonstrate that economically significant unrecovered oil remains in geologically resolvable untapped compartments; and (3) test the accuracy of reservoir characterization and flow simulation as predictive tools in resource preservation of mature fields. A geologically designed, enhanced recovery program (CO{sub 2} flood, waterflood, or polymer flood) and well-completion program will be developed, and one to three infill well will be drilled and cored. Technical progress is summarized for: geophysical characterization; reservoir characterization; outcrop characterization; and producibility problem characterization.

  11. An adaptive nonlinear solution scheme for reservoir simulation

    SciTech Connect

    Lett, G.S.

    1996-12-31

    Numerical reservoir simulation involves solving large, nonlinear systems of PDE with strongly discontinuous coefficients. Because of the large demands on computer memory and CPU, most users must perform simulations on very coarse grids. The average properties of the fluids and rocks must be estimated on these grids. These coarse grid {open_quotes}effective{close_quotes} properties are costly to determine, and risky to use, since their optimal values depend on the fluid flow being simulated. Thus, they must be found by trial-and-error techniques, and the more coarse the grid, the poorer the results. This paper describes a numerical reservoir simulator which accepts fine scale properties and automatically generates multiple levels of coarse grid rock and fluid properties. The fine grid properties and the coarse grid simulation results are used to estimate discretization errors with multilevel error expansions. These expansions are local, and identify areas requiring local grid refinement. These refinements are added adoptively by the simulator, and the resulting composite grid equations are solved by a nonlinear Fast Adaptive Composite (FAC) Grid method, with a damped Newton algorithm being used on each local grid. The nonsymmetric linear system of equations resulting from Newton`s method are in turn solved by a preconditioned Conjugate Gradients-like algorithm. The scheme is demonstrated by performing fine and coarse grid simulations of several multiphase reservoirs from around the world.

  12. Characterization of fluvial sedimentology for reservoir simulation modeling

    SciTech Connect

    Henriquez, A.; Tyler, K.J.; Hurst, A. )

    1990-09-01

    This paper presents a critical study of 3D stochastic simulation of a fluvial reservoir and of the transfer of the geological model to a reservoir simulation grid. The stochastic model is conditioned by sand-body thickness and position in wellbores. Geological input parameters-sand-body orientation and width/thickness ratios-are often difficult to determine, and are invariably subject to interpretation. Net/gross ratio (NGR) and sand-body thickness are more easily estimated. Sand-body connectedness varies, depending on the modeling procedure; however, a sedimentary process-related model gives intermediate values for connectedness between the values for a regular packing model and the stochastic model. The geological model is transferred to a reservoir simulation grid by use of transmissibility multipliers and an NGR value for each block. The transfer of data smooths out much of the detailed geological information, and the calculated recovery factors are insensitive to the continuity measured in the geological model. Hence, the authors propose improvements to the interface between geological and reservoir simulation models.

  13. Reservoir simulation in a North Sea reservoir experiencing significant compaction drive

    SciTech Connect

    Cook, C.C.; Jewell, S.

    1995-12-31

    The Valhall field in the Norwegian North Sea is a high porosity chalk reservoir undergoing primary pressure depletion. Over the last ten years there have been a number of computer modeling studies of the field which have all assumed an original oil-in-place of approximately 2,000 MMSTB (318.0{times}10{sup 6}m{sup 3}) to the present due to the addition of wells and the optimization of completion techniques. However, the single most important and unique feature influencing Valhall long term production performance is reservoir rock compaction. This paper describes the mathematical model used to simulate reservoir performance in a compacting reservoir with specific discussion regarding the proportion of oil produced by each physical recovery process. An understanding of the recovery mechanisms and their relative importance is critical for the successful management of the field. This paper also presents an alternative method for evaluating the various recovery processes using a simple solution to the material balance equation. This is used to substantiate the magnitude of the various recovery mechanisms identified in the simulation model.

  14. Reservoir simulation and the in-house vector processor: experience for the first year. [CRAY-1S

    SciTech Connect

    Killough, J.E.; Levesque, J.M.

    1982-01-01

    This paper details the changes which have been made in ARCO Oil and Gas Company's reservoir simulation models to operate more efficiently with an in-house CRAY-1S vector processor. A unique method for vectorization of a compositional reservoir simulation model is presented. A method is described for utilizing the capabilities of the CRAY-1S I/O (Input/Output) processor for problems that are not contained in memory. 6 refs.

  15. On-line Optimization-Based Simulators for Fractured and Non-fractured Reservoirs

    SciTech Connect

    Milind D. Deo

    2005-08-31

    Oil field development is a multi-million dollar business. Reservoir simulation is often used to guide the field management and development process. Reservoir characterization and geologic modeling tools have become increasingly sophisticated. As a result the geologic models produced are complex. Most reservoirs are fractured to a certain extent. The new geologic characterization methods are making it possible to map features such as faults and fractures, field-wide. Significant progress has been made in being able to predict properties of the faults and of the fractured zones. Traditionally, finite difference methods have been employed in discretizing the domains created by geologic means. For complex geometries, finite-element methods of discretization may be more suitable. Since reservoir simulation is a mature science, some of the advances in numerical methods (linear, nonlinear solvers and parallel computing) have not been fully realized in the implementation of most of the simulators. The purpose of this project was to address some of these issues. {sm_bullet} One of the goals of this project was to develop a series of finite-element simulators to handle problems of complex geometry, including systems containing faults and fractures. {sm_bullet} The idea was to incorporate the most modern computing tools; use of modular object-oriented computer languages, the most sophisticated linear and nonlinear solvers, parallel computing methods and good visualization tools. {sm_bullet} One of the tasks of the project was also to demonstrate the construction of fractures and faults in a reservoir using the available data and to assign properties to these features. {sm_bullet} Once the reservoir model is in place, it is desirable to find the operating conditions, which would provide the best reservoir performance. This can be accomplished by utilization optimization tools and coupling them with reservoir simulation. Optimization-based reservoir simulation was one of the

  16. Numerical Simulation for Natural State of Two-Phase Liquid Dominated Geothermal Reservoir with Steam Cap Underlying Brine Reservoir

    NASA Astrophysics Data System (ADS)

    Pratama, Heru Berian; Miryani Saptadji, Nenny

    2016-09-01

    Hydrothermal reservoir which liquid-dominated hydrothermal reservoir is a type of geothermal reservoir that most widely used for power plant. The exploitation of mass and heat from the geothermal fluid will decrease the pressure in the reservoir over time. Therefore the pressure drop in the reservoir will have an impact on the formation of boiling zones or boiling will increase. The impacts are an increase in the fraction of steam, dryness, in the reservoir and with good vertical permeability will form a steam cap underlying the brine reservoir. The two- phase liquid dominated reservoir is sensitive to the porosity and difficult to assign average properties of the entire reservoir when there is boiling zone in some area of the reservoir. These paper showed successful development of two-phase liquid dominated geothermal reservoir and discussed the formation of steam cap above brine reservoir through numerical simulation for state natural conditions. The natural state modeling in steam cap shows a match with the conceptual model of the vapor-dominated developed. These paper also proofed the presence of transition zone, boiling zone, between steam cap and brine reservoir.

  17. Multigrid Methods for Fully Implicit Oil Reservoir Simulation

    NASA Technical Reports Server (NTRS)

    Molenaar, J.

    1996-01-01

    In this paper we consider the simultaneous flow of oil and water in reservoir rock. This displacement process is modeled by two basic equations: the material balance or continuity equations and the equation of motion (Darcy's law). For the numerical solution of this system of nonlinear partial differential equations there are two approaches: the fully implicit or simultaneous solution method and the sequential solution method. In the sequential solution method the system of partial differential equations is manipulated to give an elliptic pressure equation and a hyperbolic (or parabolic) saturation equation. In the IMPES approach the pressure equation is first solved, using values for the saturation from the previous time level. Next the saturations are updated by some explicit time stepping method; this implies that the method is only conditionally stable. For the numerical solution of the linear, elliptic pressure equation multigrid methods have become an accepted technique. On the other hand, the fully implicit method is unconditionally stable, but it has the disadvantage that in every time step a large system of nonlinear algebraic equations has to be solved. The most time-consuming part of any fully implicit reservoir simulator is the solution of this large system of equations. Usually this is done by Newton's method. The resulting systems of linear equations are then either solved by a direct method or by some conjugate gradient type method. In this paper we consider the possibility of applying multigrid methods for the iterative solution of the systems of nonlinear equations. There are two ways of using multigrid for this job: either we use a nonlinear multigrid method or we use a linear multigrid method to deal with the linear systems that arise in Newton's method. So far only a few authors have reported on the use of multigrid methods for fully implicit simulations. Two-level FAS algorithm is presented for the black-oil equations, and linear multigrid for

  18. Parallelization of a Compositional Reservoir Simulator

    NASA Astrophysics Data System (ADS)

    Reme, Hilde; Åge Øye, Geir; Espedal, Magne S.; Fladmark, Gunnar E.

    A finite volume dicretization has been used to solve compositional flow in porous media. Secondary migration in fractured rocks has been the main motivation for the work. Multipoint flux approximation has been implemented and adaptive local grid refinement, based on domain decomposition, is used at fractures and faults. The parallelization method, which is described in this paper, strongly promotes code reuse and gives a very high level of parallelization despite low implementation costs. The programming framework is also portable to other platforms or other applications. We have presented computer experiments to examine the parallel efficiency of the implemented parallel simulator with respect to scalability and speedup. Keywords: porous media, multipoint flux approximation, domain decomposition, parallelization

  19. Simulation of Reservoir Systems with HEC-5 on a Personal Computer

    DTIC Science & Technology

    1990-03-01

    purpose, Multi- reservoir Simulation on a PC Technical Paper No. 123, Developing and Managing a Comprehensive Reservoir Analysis Model 2 INFIVE ORCOED...Program HEC-5..." and " Reservoir Simulation has begun:" (Figure 10). ’ l i ’ :I’ I , Figure 10. Interactive HEC-5: Main Screen 24 During simulation, an...April 1988. 14. U.S. Army Corps of Engineers, Hydrologic Engineering Center, "Multi-Purpose, Multi- Reservoir Simulation on a PC ", Technical Paper No

  20. Compositional reservoir simulation on CM-5 and KSR-1 parallel machines

    SciTech Connect

    Ghori, S.G.; Wang, C.H.; Lim, M.T.; Pope, G.A.; Sepehrnoori, K.; Wheeler, M.F.

    1995-12-31

    Recently, use of parallel machines in reservoir simulation has received considerable attention from the petroleum industry. This paper presents parallelization of a 3D compositional, equation-of-state reservoir simulator on the CM-5 and KSR-1. To the best of the authors` knowledge, this is the first time that the parallelization of a compositional reservoir simulator has been performed on both the CM-5 and KSR-1. For new users of the CM-5 machines, the software and hardware of CM-5 architecture is presented, as well as details of the parallelization techniques. For example, domain decomposition, I/O`s, phase equilibrium computations, and well model are described. The parallelism techniques on the KSR-1 are presented with the emphasis on the porting of the phase equilibrium calculation. The performance of each machine is evaluated by showing the speedup on different sets of processing nodes. Two test problems were used to explore the capability of the parallelized version of the code; one is a waterflood problem and the other is a CO{sub 2} multiple contact miscible flood, both in a West Texas oil field. These field problems were run on 1, 2, 4, 8, 16, and 32 processors to get insight into the locations of communication bottlenecks, generally occurring in the programming with distributed memory machines. The problems of latency and bandwidth which are associated with communication efficiency of the CM-5 are also addressed.

  1. Water-Balance Simulations of Runoff and Reservoir Storage for the Upper Helmand Watershed and Kajakai Reservoir, Central Afghanistan

    USGS Publications Warehouse

    Vining, Kevin C.; Vecchia, Aldo V.

    2007-01-01

    A study was performed to provide information on monthly historical and hypothetical future runoff for the Upper Helmand watershed and reservoir storage in Kajakai Reservoir that could be used by Afghanistan authorities to make economic and demographic decisions concerning reservoir design and operation, reservoir sedimentation, and development along the Helmand River. Estimated reservoir volume at the current spillway elevation of 1,033.5 meters decreased by about 365 million cubic meters from 1968 to 2006 because of sedimentation. Water-balance simulations indicated a good fit between modeled and recorded monthly runoff at the two gaging stations in the watershed for water years 1956-79 and indicated an excellent fit between modeled and recorded monthly changes in Kajakai Reservoir storage for water years 1956-79. Future simulations, which included low starting reservoir water levels and a spillway raised to an elevation of 1,045 meters, indicated that the reservoir is likely to fill within 2 years. Although Kajakai Reservoir is likely to fill quickly, multiyear deficits may still occur. If future downstream irrigation demand doubles but future precipitation, temperature, and reservoir sedimentation remain similar to historical conditions, the reservoir would have more than a 50-percent chance of being full during April or May of a typical year. Future simulations with a 10-percent reduction in precipitation indicated that supply deficits would occur more than 1 in 4 years, on average, during August, September, or October. The reservoir would be full during April or May fewer than 1 in 2 years, on average, and multiyear supply deficits could occur. Increased sedimentation had little effect on reservoir levels during April through July, but the frequency of deficits increased substantially during September and October.

  2. NFFLOW: A reservoir simulator incorporating explicit fractures (SPE 153890)

    SciTech Connect

    Boyle, E.J.; Sams, W.N.

    2012-01-01

    NFFLOW is a research code that quickly and inexpensively simulates flow in moderately fractured reservoirs. It explicitly recognizes fractures separately from rock matrix. In NFFLOW fracture flow is proportional to the pressure gradient along the fracture, and flow in the rock matrix is determined by Darcy’s Law. The two flow mechanisms are coupled through the pressure gradient between a fracture and its adjacent rock matrix. Presented is a promising change to NFFLOW that allows for flow across a rock matrix block.

  3. Reservoir simulation studies: Wairakei Geothermal Field, New Zealand. Final report

    SciTech Connect

    Pritchett, J.W.; Rice, L.F.; Garg, S.K.

    1980-01-01

    Numerical reservoir simulation techniques were used to perform a history-match of the Wairakei geothermal system in New Zealand. First, a one-dimensional (vertical) model was chosen; realistic stratigraphy was incorporated and the known production history was imposed. The effects of surface and deep recharge were included. Good matches were obtained, both for the reservoir pressure decline history and changes in average discharge enthalpy with time. Next, multidimensional effects were incorporated by treating with a two-dimensional vertical section. Again, good history matches were obtained, although computed late-time discharge enthalpies were slightly high. It is believed that this disparity arises from inherently three-dimensional effects. Predictive calculations using the two-dimensional model suggest that continued future production will cause little additional reservoir pressure drop, but that thermal degradation will occur. Finally, ground subsidence data at Wairakei was examined. It was concluded that traditional elastic pore-collapse models based on classical soil-mechanics concepts are inadequate to explain the observed surface deformation. It is speculated that the measured subsidence may be due to structural effects such as aseismic slippage of a buried reservoir boundary fault.

  4. Estimation of discontinuous coefficients in parabolic systems - Applications to reservoir simulation

    NASA Technical Reports Server (NTRS)

    Lamm, Patricia K.

    1987-01-01

    Spline-based techniques for estimating spatially varying parameters that appear in parabolic distributed systems (typical of those found in reservoir simulation problems) are presented. In particular, the problem of determining discontinuous coefficients is discussed, estimating both the functional shape and points of discontinuity for such parameters. In addition, the ideas may also be applied to problems with unknown initial conditions and unknown parameters appearing in terms representing external forces. Convergence results and a summary of numerical performance of the resulting algorithms are given.

  5. Galerkin finite-element simulation of a geothermal reservoir

    USGS Publications Warehouse

    Mercer, J.W.; Pinder, G.F.

    1973-01-01

    The equations describing fluid flow and energy transport in a porous medium can be used to formulate a mathematical model capable of simulating the transient response of a hot-water geothermal reservoir. The resulting equations can be solved accurately and efficiently using a numerical scheme which combines the finite element approach with the Galerkin method of approximation. Application of this numerical model to the Wairakei geothermal field demonstrates that hot-water geothermal fields can be simulated using numerical techniques currently available and under development. ?? 1973.

  6. Numerical simulation of reservoir parameters' synergetic time-variability on development rules.

    PubMed

    Hou, Jian; Zhang, Yanhui; Wang, Daigang; Zhou, Kang

    2016-01-01

    Time variability of reservoir parameters in water flooding has an effect on oilfield development rules. Meanwhile, time variability of different reservoir macro-parameters has certain synergetic relationship with each other. Based on microscopic network simulation and reservoir numerical simulation, a new simulation method is presented, which can describe the influence of reservoir parameters' synergetic time-variability on oilfield development rules both in macroscopic and microscopic scales. Microscopic network simulation can effectively simulate the impact of micro-parameters' variation on macro-parameters, thus a comprehensive model is built to reflect the variability of reservoir parameters. On the basis of considering time variability of porosity, permeability, and relative permeability in water flooding, an improved reservoir numerical simulator is established, which can effectively simulate the effect of reservoir parameters' synergetic variation on oilfield development rules.

  7. Assessment of uncertainty and degasification efficiency in coal seam gas drainage through stochastic reservoir simulation

    NASA Astrophysics Data System (ADS)

    Özgen Karacan, C.

    2016-04-01

    Coal seam degasification improves coal mine safety by reducing the gas content of coal seams and also by generating added value as an energy source. Coal bed reservoir simulation, as a reservoir management and forecasting tool, is one of the most effective ways to help with these two main objectives. However, as in all modeling and simulation studies, reservoir description and whether observed productions can be predicted are important considerations. Using geostatistical realizations as spatial maps of different coal reservoir properties is a more realistic approach than assuming uniform properties across the field. In fact, this approach can help with simultaneous history matching of multiple wellbores to enhance the confidence in spatial models of different coal properties that are pertinent to degasification. The problem that still remains, however, is the uncertainty in geostatistical, and thus reservoir, simulations originating from partial sampling of the seam that does not properly reflect the stochastic nature of coal property realizations. This study demonstrates the use of geostatistical realizations generated through sequential Gaussian simulation and co-simulation techniques and assesses the uncertainty in coal seam reservoir simulations with history matching errors. 100 individual realizations of 10 coal properties were generated using geostatistical techniques. These realizations were used to create 100 realization bundles (property datasets). Each of these bundles was then used in coal seam reservoir simulations for simultaneous history matching of degasification wells. History matching errors for each bundle were evaluated and the single set of realizations that would minimize the error for all wells was defined. Errors were compared with those of E-type and the average realization of the best matches. The study helped to determine the realization bundle that consisted of the spatial maps of coal properties, which resulted in minimum error. In

  8. Reservoir simulation studies on the Cerro Prieto geothermal field

    SciTech Connect

    Castaneda, M.; Abril, A.; Arellano, V.; Marquez, R.

    1982-01-01

    A reservoir engineering and simulation study is being carried out on the Cerro Prieto geothermal field. A preliminary material balance has been applied to the old part of this field. A single block with constant properties in the horizontal direction was used for this preliminary material balance. The vertical block column was subdivided in several levels in order to take into account the known lithologic column. From existing pressure and enthalpy field histories, a single phase (liquid) reservoir assumption was selected. Under this assumption, a lateral radial recharge was considered in obtaining the pressure and enthalpy history match. These preliminary results indicate that another type of recharge is probably taking place in this part of the field, rather than lateral radial.

  9. Scale Model Simulation of Enhanced Geothermal Reservoir Creation

    NASA Astrophysics Data System (ADS)

    Gutierrez, M.; Frash, L.; Hampton, J.

    2012-12-01

    Geothermal energy technology has successfully provided a means of generating stable base load electricity for many years. However, implementation has been spatially limited to limited availability of high quality traditional hydro-thermal resources possessing the combination of a shallow high heat flow anomaly and an aquifer with sufficient permeability and continuous fluid recharge. Enhanced Geothermal Systems (EGS) has been proposed as a potential solution to enable additional energy production from the non-conventional hydro-thermal resources. Hydraulic fracturing is considered the primary means of creating functional EGS reservoirs at sites where the permeability of the rock is too limited to allow cost effective heat recovery. EGS reservoir creation requires improved fracturing methodology, rheologically controllable fracturing fluids, and temperature hardened proppants. Although large fracture volumes (several cubic km) have been created in the field, circulating fluid through these full volumes and maintaining fracture volumes have proven difficult. Stimulation technology and methodology as used in the oil and gas industry for sedimentary formations are well developed; however, they have not sufficiently been demonstrated for EGS reservoir creation. Insufficient data and measurements under geothermal conditions make it difficult to directly translate experience from the oil and gas industries to EGS applications. To demonstrate the feasibility of EGS reservoir creation and subsequent geothermal energy production, and to improve the understanding of hydraulic and propping in EGS reservoirs, a heated true-triaxial load cell with a high pressure fluid injection system was developed to simulate an EGS system from stimulation to production. This apparatus is capable of loading a 30x30x30 cubic cm rock sample with independent principal stresses up to 13 MPa while simultaneously providing heating up to 180 degree C. Multiple orientated boreholes of 5 to 10 mm

  10. An inverse problem solution to the flow of tracers in naturally fractured reservoirs

    SciTech Connect

    Jetzabeth Ramirez S.; Fernando Samaniego V.; Fernando Rodriguez; Jesus Rivera R.

    1994-01-20

    This paper presents a solution for the inverse problem to the flow of tracers in naturally fractured reservoirs. The models considered include linear flow in vertical fractures, radial flow in horizontal fractures, and cubic block matrix-fracture geometry. The Rosenbrock method for nonlinear regression used in this study, allowed the estimation of up to six parameters for the cubic block matrix fracture geometry. The nonlinear regression for the three cases was carefully tested against syntetical tracer concentration responses affected by random noise, with the objective of simulating as close as possible step injection field data. Results were obtained within 95 percent confidence limits. The sensitivity of the inverse problem solution on the main parameters that describe this flow problem was investigated. The main features of the nonlinear regression program used in this study are also discussed. The procedure of this study can be applied to interpret tracer tests in naturally fractured reservoirs, allowing the estimation of fracture and matrix parameters of practical interest (longitudinal fracture dispersivity alpha, matrix porosity phi2, fracture half-width w, matrix block size d, matrix diffusion coefficient D2 and the adsorption constant kd). The methodology of this work offers a practical alternative for tracer flow tests interpretation to other techniques.

  11. Improved storage efficiency through geologic modeling and reservoir simulation

    SciTech Connect

    Ammer, J.R.; Mroz, T.H.; Covatch, G.L.

    1997-11-01

    The US Department of Energy (DOE), through partnerships with industry, is demonstrating the importance of geologic modeling and reservoir simulation for optimizing the development and operation of gas storage fields. The geologic modeling and reservoir simulation study for the Natural Fuel Gas Supply Corporation CRADA was completed in September 1995. The results of this study were presented at the 1995 Society of Petroleum Engineers` (SPE) Eastern Regional Meeting. Although there has been no field verification of the modeling results, the study has shown the potential advantages and cost savings opportunities of using horizontal wells for storage enhancement. The geologic modeling for the Equitrans` CRADA was completed in September 1995 and was also presented at the 1995 SPE Eastern Regional Meeting. The reservoir modeling of past field performance was completed in November 1996 and prediction runs are currently being made to investigate the potential of offering either a 10 day or 30 day peaking service in addition to the existing 110 day base load service. Initial results have shown that peaking services can be provided through remediation of well damage and by drilling either several new vertical wells or one new horizontal well. The geologic modeling for the Northern Indiana Public Service Company CRADA was completed in November 1996 with a horizontal well being completed in January 1997. Based on well test results, the well will significantly enhance gas deliverability from the field and will allow the utilization of gas from an area of the storage field that was not accessible from their existing vertical wells. Results are presented from these three case studies.

  12. The parallel subdomain-levelset deflation method in reservoir simulation

    NASA Astrophysics Data System (ADS)

    van der Linden, J. H.; Jönsthövel, T. B.; Lukyanov, A. A.; Vuik, C.

    2016-01-01

    Extreme and isolated eigenvalues are known to be harmful to the convergence of an iterative solver. These eigenvalues can be produced by strong heterogeneity in the underlying physics. We can improve the quality of the spectrum by 'deflating' the harmful eigenvalues. In this work, deflation is applied to linear systems in reservoir simulation. In particular, large, sudden differences in the permeability produce extreme eigenvalues. The number and magnitude of these eigenvalues is linked to the number and magnitude of the permeability jumps. Two deflation methods are discussed. Firstly, we state that harmonic Ritz eigenvector deflation, which computes the deflation vectors from the information produced by the linear solver, is unfeasible in modern reservoir simulation due to high costs and lack of parallelism. Secondly, we test a physics-based subdomain-levelset deflation algorithm that constructs the deflation vectors a priori. Numerical experiments show that both methods can improve the performance of the linear solver. We highlight the fact that subdomain-levelset deflation is particularly suitable for a parallel implementation. For cases with well-defined permeability jumps of a factor 104 or higher, parallel physics-based deflation has potential in commercial applications. In particular, the good scalability of parallel subdomain-levelset deflation combined with the robust parallel preconditioner for deflated system suggests the use of this method as an alternative for AMG.

  13. The benefits of enhanced integration capabilities in 3-D reservoir modelling and simulation

    SciTech Connect

    O`Rourke, S.T.; Ikwumonu, A.

    1996-12-31

    The use of proprietary, closely linked 3-D geological and reservoir simulation software has greatly enhanced the reservoir modelling process by enabling complete integration of geological and engineering data in a 3-D manner. The software were used to model and simulate a deltaic sandstone reservoir in the Nigerian Forcados Yokri field in order to describe the reservoir sweep pattern. A simple simulation of the reservoir was first carried out to identify the main controls on the reservoir performance, which in this case were the intra-reservoir shales. As they are the only baffles or barriers to flow, proper modelling of them was critical to achieving a history match. Well logs, 3-D seismic, limited core data and sequence stratigraphic concepts were used to define a three dimensional depositional model which was then used to guide the 3-D reservoir architecture modelling. The reservoir model was evaluated in the 3-D simulator and, when the initial model did not yield a proper match with the historical production data, alternative models were easily generated and simulated until an acceptable match was achieved. The result was a 10% increase in predicted ultimate recovery, a better understanding of the reservoir and an optimized reservoir depletion plan.

  14. CO/sub 2/ Huff-Puff simulation using a compositional reservoir simulator

    SciTech Connect

    Hsu, H.H.; Brugman, R.J.

    1986-01-01

    Increased field application of the CO/sub 2/ Huff-Puff process has resulted in increased laboratory and numerical simulation activity. This paper focuses on numerical simulation of the CO/sub 2/ Huff-Puff process in a light oil reservoir, using a fully-compositional reservoir simulator. A simulation model is first validated by successfully history-matching production data from two huff-puff cycles. A performance prediction is then conducted for a third cycle. A number of parametric runs are performed to determine oil recovery as affected by: 1. The number of cycles; 2. The timing of injection, soak and back-production operations; and 3. The quantity and composition of the injected solvent.

  15. A generalized well management scheme for reservoir simulation

    SciTech Connect

    Fang, W.Y.; Lo, K.K.

    1995-12-31

    A new generalized well management scheme has been formulated to maximize oil production under multiple facility constraints. The scheme integrates reserve performance, wellbore hydraulics, surface facility constraints and lift-gas allocation o maximize oil production. It predicts well performance based on up-to-date hydraulics and reservoir conditions. The scheme has been implemented in a black oil simulator by using Separable programming and Simplex algorithm. This production optimization scheme has been applied to two full-field models. The oil production of these two full-field models is limited by water, gas and liquid haling limits at both field- and flow station-levels. The gas production is limited by injectivity as well as gas handling limits. For a 12-year production forecast on Field A, the new scheme increased oil production by 3 to 9%. For a 12-year production forecast on field B, the new scheme increased oil production by 7 to 9%.

  16. Foam flooding reservoir simulation algorithm improvement and application

    NASA Astrophysics Data System (ADS)

    Wang, Yining; Wu, Xiaodong; Wang, Ruihe; Lai, Fengpeng; Zhang, Hanhan

    2014-05-01

    As one of the important enhanced oil recovery (EOR) technologies, Foam flooding is being used more and more widely in the oil field development. In order to describe and predict foam flooding, experts at domestic and abroad have established a number of mathematical models of foam flooding (mechanism, empirical and semi-empirical models). Empirical models require less data and apply conveniently, but the accuracy is not enough. The aggregate equilibrium model can describe foam generation, burst and coalescence by mechanism studying, but it is very difficult to accurately describe. The research considers the effects of critical water saturation, critical concentration of foaming agent and critical oil saturation on the sealing ability of foam and considers the effect of oil saturation on the resistance factor for obtaining the gas phase relative permeability and the results were amended by laboratory test, so the accuracy rate is higher. Through the reservoir development concepts simulation and field practical application, the calculation is more accurate and higher.

  17. Deriving multiple near-optimal solutions to deterministic reservoir operation problems

    NASA Astrophysics Data System (ADS)

    Liu, Pan; Cai, Ximing; Guo, Shenglian

    2011-08-01

    Even deterministic reservoir operation problems with a single objective function may have multiple near-optimal solutions (MNOS) whose objective values are equal or sufficiently close to the optimum. MNOS is valuable for practical reservoir operation decisions because having a set of alternatives from which to choose allows reservoir operators to explore multiple options whereas the traditional algorithm that produces a single optimum does not offer them this flexibility. This paper presents three methods: the near-shortest paths (NSP) method, the genetic algorithm (GA) method, and the Markov chain Monte Carlo (MCMC) method, to explore the MNOS. These methods, all of which require a long computation time, find MNOS using different approaches. To reduce the computation time, a narrower subspace, namely a near-optimal space (NOSP, described by the maximum and minimum bounds of MNOS) is derived. By confining the MNOS search within the NOSP, the computation time of the three methods is reduced. The proposed methods are validated with a test function before they are examined with case studies of both a single reservoir (the Three Gorges Reservoir in China) and a multireservoir system (the Qing River Cascade Reservoirs in China). It is found that MNOS exists for the deterministic reservoir operation problems. When comparing the three methods, the NSP method is unsuitable for large-scale problems but provides a benchmark to which solutions of small- and medium-scale problems can be compared. The GA method can produce some MNOS but is not very efficient in terms of the computation time. Finally, the MCMC method performs best in terms of goodness-of-fit to the benchmark and computation time, since it yields a wide variety of MNOS based on all retained intermediate results as potential MNOS. Two case studies demonstrate that the MNOS identified in this study are useful for real-world reservoir operation, such as the identification of important operation time periods and

  18. Modeling of geothermal reservoirs: Fundamental processes, computer simulation, and field applications

    SciTech Connect

    Pruess, K.

    1988-09-01

    This article attempts to critically evaluate the present state of the art of geothermal reservoir simulation. Methodological aspects of geothermal reservoir modeling are briefly reviewed, with special emphasis on flow in fractured media. Then we examine applications of numerical simulation to studies of reservoir dynamics, well test design and analysis, and modeling of specific fields. Tangible impacts of reservoir simulation technology on geothermal energy development are pointed out. We conclude with considerations on possible future developments in the mathematical modeling of geothermal fields. 45 refs., 4 figs., 2 tabs.

  19. Predicting the natural state of fractured carbonate reservoirs: An Andector Field, West Texas test of a 3-D RTM simulator

    SciTech Connect

    Tuncay, K.; Romer, S.; Ortoleva, P.; Hoak, T.; Sundberg, K.

    1998-12-31

    The power of the reaction, transport, mechanical (RTM) modeling approach is that it directly uses the laws of geochemistry and geophysics to extrapolate fracture and other characteristics from the borehole or surface to the reservoir interior. The objectives of this facet of the project were to refine and test the viability of the basin/reservoir forward modeling approach to address fractured reservoir in E and P problems. The study attempts to resolve the following issues: role of fracturing and timing on present day location and characteristics; clarifying the roles and interplay of flexure dynamics, changing rock rheological properties, fluid pressuring and tectonic/thermal histories on present day reservoir location and characteristics; and test the integrated RTM modeling/geological data approach on a carbonate reservoir. Sedimentary, thermal and tectonic data from Andector Field, West Texas, were used as input to the RTM basin/reservoir simulator to predict its preproduction state. The results were compared with data from producing reservoirs to test the RTM modeling approach. The effects of production on the state of the field are discussed in a companion report. The authors draw the following conclusions: RTM modeling is an important new tool in fractured reservoir E and P analysis; the strong coupling of RTM processes and the geometric and tensorial complexity of fluid flow and stresses require the type of fully coupled, 3-D RTM model for fracture analysis as pioneered in this project; flexure analysis cannot predict key aspects of fractured reservoir location and characteristics; fracture history over the lifetime of a basin is required to understand the timing of petroleum expulsion and migration and the retention properties of putative reservoirs.

  20. Multi-purpose, multi-reservoir simulation on a PC. Technical paper

    SciTech Connect

    Eichert, B.S.; Franke, C.

    1988-08-01

    The methodology and difficulties in converting a large, general-purpose, mainframe, batch-oriented computer program (for reservoir simulation) to work effectively in the PC environment are described in this paper. A brief overview of the present capabilities of the general purpose reservoir simulation program (HEC-5), which works on mainframe and MS DOS compatible computers, is also presented.

  1. Advanced Techniques for Reservoir Simulation and Modeling of Non-Conventional Wells

    SciTech Connect

    Durlofsky, Louis J.

    2000-08-28

    This project targets the development of (1) advanced reservoir simulation techniques for modeling non-conventional wells; (2) improved techniques for computing well productivity (for use in reservoir engineering calculations) and well index (for use in simulation models), including the effects of wellbore flow; and (3) accurate approaches to account for heterogeneity in the near-well region.

  2. Static and dynamic load-balancing strategies for parallel reservoir simulation

    SciTech Connect

    Anguille, L.; Killough, J.E.; Li, T.M.C.; Toepfer, J.L.

    1995-12-31

    Accurate simulation of the complex phenomena that occur in flow in porous media can tax even the most powerful serial computers. Emergence of new parallel computer architectures as a future efficient tool in reservoir simulation may overcome this difficulty. Unfortunately, major problems remain to be solved before using parallel computers commercially: production serial programs must be rewritten to be efficient in parallel environments and load balancing methods must be explored to evenly distribute the workload on each processor during the simulation. This study implements both a static load-balancing algorithm and a receiver-initiated dynamic load-sharing algorithm to achieve high parallel efficiencies on both the IBM SP2 and Intel IPSC/860 parallel computers. Significant speedup improvement was recorded for both methods. Further optimization of these algorithms yielded a technique with efficiencies as high as 90% and 70% on 8 and 32 nodes, respectively. The increased performance was the result of the minimization of message-passing overhead.

  3. Numerical simulation of water injection into vapor-dominated reservoirs

    SciTech Connect

    Pruess, K.

    1995-01-01

    Water injection into vapor-dominated reservoirs is a means of condensate disposal, as well as a reservoir management tool for enhancing energy recovery and reservoir life. We review different approaches to modeling the complex fluid and heat flow processes during injection into vapor-dominated systems. Vapor pressure lowering, grid orientation effects, and physical dispersion of injection plumes from reservoir heterogeneity are important considerations for a realistic modeling of injection effects. An example of detailed three-dimensional modeling of injection experiments at The Geysers is given.

  4. Developing the aquatic-coupled reservoir model to simulate carbon dioxide emission from a young boreal hydroelectric reservoir

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Roulet, N. T.; Strachan, I. B.; Tremblay, A.

    2013-12-01

    We developed a process-based biogeochemical reservoir model, called AF-DNDC (Aquatic-coupled Forest-DNDC), to project carbon (C) flux from water surface of a recently created hydro-electric reservoir that flooded a boreal landscape. The basis of the reservoir model is Forest-DNDC, a biogeochemical model for C and nitrogen cycling in forests and wetlands. AF-DNDC was developed by coupling a lake C model to a flooded version of Forest-DNDC. AF-DNDC includes the C cycling through the aquatic carbon pools, such as DIC (dissolved inorganic C), DOC (dissolved organic C), and planktonic community as well as C exchange between air, water, and sediment. AF-DNDC was used to examine the net change in carbon dioxide (CO2) exchange between the surface and the atmosphere over the first seven years post flooding of the Eastmain-1 reservoir in northern Quebec. With present day climate and environmental conditions, simulated daily CO2 emissions from the flooded forest averaged 1.69 g C m-2 d-1 (range 0 to 20.49), and from the flooded peatland averaged 0.87 g C m-2 d-1 (range 0 to 6.86). Simulated CO2 emissions decreased with the age of reservoir. They were larger than eddy-covariance measured CO2 fluxes from the water surface over flooded forests, but compared well to the eddy-covariance fluxes during the open-water period. The simulated emissions were significantly correlated with the measured fluxes from the flooded forest (r2 = 0.33; p < 0.01) and flooded peatland (r2 = 0.41; p < 0.01). The patterns over the year were similar. AF-DNDC is suitable for use to assess the major changes in CO2 exchange due to the creation of reservoirs in boreal regions.

  5. Geothermal reservoir simulation to enhance confidence in predictions for nuclear waste disposal

    SciTech Connect

    Kneafsey, Timothy J.; Pruess, Karsten; O'Sullivan, Michael J.; Bodvarsson, Gudmundur S.

    2002-06-15

    Numerical simulation of geothermal reservoirs is useful and necessary in understanding and evaluating reservoir structure and behavior, designing field development, and predicting performance. Models vary in complexity depending on processes considered, heterogeneity, data availability, and study objectives. They are evaluated using computer codes written and tested to study single and multiphase flow and transport under nonisothermal conditions. Many flow and heat transfer processes modeled in geothermal reservoirs are expected to occur in anthropogenic thermal (AT) systems created by geologic disposal of heat-generating nuclear waste. We examine and compare geothermal systems and the AT system expected at Yucca Mountain, Nevada, and their modeling. Time frames and spatial scales are similar in both systems, but increased precision is necessary for modeling the AT system, because flow through specific repository locations will affect long-term ability radionuclide retention. Geothermal modeling experience has generated a methodology, used in the AT modeling for Yucca Mountain, yielding good predictive results if sufficient reliable data are available and an experienced modeler is involved. Codes used in geothermal and AT modeling have been tested extensively and successfully on a variety of analytical and laboratory problems.

  6. On an iterative ensemble smoother and its application to a reservoir facies estimation problem

    NASA Astrophysics Data System (ADS)

    Luo, Xiaodong; Chen, Yan; Valestrand, Randi; Stordal, Andreas; Lorentzen, Rolf; Nævdal, Geir

    2014-05-01

    For data assimilation problems there are different ways in utilizing the available observations. While certain data assimilation algorithms, for instance, the ensemble Kalman filter (EnKF, see, for examples, Aanonsen et al., 2009; Evensen, 2006) assimilate the observations sequentially in time, other data assimilation algorithms may instead collect the observations at different time instants and assimilate them simultaneously. In general such algorithms can be classified as smoothers. In this aspect, the ensemble smoother (ES, see, for example, Evensen and van Leeuwen, 2000) can be considered as an smoother counterpart of the EnKF. The EnKF has been widely used for reservoir data assimilation (history matching) problems since its introduction to the community of petroleum engineering (Nævdal et al., 2002). The applications of the ES to reservoir data assimilation problems are also investigated recently (see, for example, Skjervheim and Evensen, 2011). Compared to the EnKF, the ES has certain technical advantages, including, for instance, avoiding the restarts associated with each update step in the EnKF and also having fewer variables to update, which may result in a significant reduction in simulation time, while providing similar assimilation results to those obtained by the EnKF (Skjervheim and Evensen, 2011). To further improve the performance of the ES, some iterative ensemble smoothers are suggested in the literature, in which the iterations are carried out in the forms of certain iterative optimization algorithms, e.g., the Gaussian-Newton (Chen and Oliver, 2012) or the Levenberg-Marquardt method (Chen and Oliver, 2013; Emerick and Reynolds, 2012), or in the context of adaptive Gaussian mixture (AGM, see Stordal and Lorentzen, 2013). In Emerick and Reynolds (2012) the iteration formula is derived based on the idea that, for linear observations, the final results of the iterative ES should be equal to the estimate of the EnKF. In Chen and Oliver (2013), the

  7. Compositional Space Parameterization Approach for Reservoir Flow Simulation

    NASA Astrophysics Data System (ADS)

    Voskov, D.

    2011-12-01

    an adaptive tabulation procedure for the parameterization of the compositional space. Since a single tie-simplex 'supports' (i.e., identifies the phase-state of) a large number of compositions in its vicinity, the efficiency gains of adaptive construction are considerable. I will present the comparison of our adaptive tie-simplex parameterization method with conventional EoS (Equation-of-State) procedures for two- and three-phase displacements in homogeneous and heterogeneous reservoirs. The results indicate clearly that the new method is at least an order-of-magnitude more efficient than conventional EoS methods for two-phase flow. For multi-phase systems the approach helps to increase robustness of phase change identification that improves a stability of multi-phase flow simulation.

  8. Simulating annual glacier flow with a linear reservoir model

    NASA Astrophysics Data System (ADS)

    Span, Norbert; Kuhn, Michael

    2003-05-01

    In this paper we present a numerical simulation of the observation that most alpine glaciers have reached peak velocities in the early 1980s followed by nearly exponential decay of velocity in the subsequent decade. We propose that similarity exists between precipitation and associated runoff hydrograph in a river basin on one side and annual mean specific mass balance of the accumulation area of alpine glaciers and ensuing changes in ice flow on the other side. The similarity is expressed in terms of a linear reservoir with fluctuating input where the year to year change of ice velocity is governed by two terms, a fraction of the velocity of the previous year as a recession term and the mean specific balance of the accumulation area of the current year as a driving term. The coefficients of these terms directly relate to the timescale, the mass balance/altitude profile, and the geometric scale of the glacier. The model is well supported by observations in the upper part of the glacier where surface elevation stays constant to within ±5 m over a 30 year period. There is no temporal trend in the agreement between observed and modeled horizontal velocities and no difference between phases of acceleration and phases of deceleration, which means that the model is generally valid for a given altitude on a given glacier.

  9. 3D scientific visualization of reservoir simulation post-processing

    SciTech Connect

    Sousa, M.C.; Miranda-Filho, D.N.

    1994-12-31

    This paper describes a 3D visualization software designed at PETROBRAS and TecGraf/PUC-RJ in Brazil for the analysis of reservoir engineering post-processing data. It offers an advanced functional environment on graphical workstations with intuitive and ergonomic interface. Applications to real reservoir models show the enriching features of the software.

  10. Long-term Reservoir Routing Simulations Using Data-Driven Approaches

    NASA Astrophysics Data System (ADS)

    Ashouri, H.; Chowdhary, H.; Chinnayakanahalli, K.; Dodov, B.

    2015-12-01

    Flood is a highly complex natural hazard that accounts for major losses to human societies worldwide. Dams built with the aim of mitigating the flood risk significantly modify river flow regimes but unavailability and/or inaccessibility of proper information about reservoir operational rules impose a big hurdle to global flood modeling. This is specifically critical for flood-prone regions where lack of proper representation of reservoir operation can lead to significant under- or overestimation of the flood magnitude, risk, and losses. With the availability of longer in-situ observational data records, as well as advancements in satellite altimetry techniques for measuring reservoir levels, operational rules can be indirectly deduced. In this study, the observed reservoir levels as well as the historical and forecast time series of inflows are incorporated into a stochastic autoregressive moving average statistical modeling scheme to simulate the releases from the dam at each time step. The resulting operational rule curve is used in a reservoir simulation model to simulate the outflows from the reservoirs. The efficiency of the model is examined for three case studies in the United States, including John Martin Reservoir (CO), Coralville Lake (IA, and specifically for the devastating 2008 flood in the state), and Boca Reservoir (CA). Statistical measures are derived and tested to evaluate the accuracy of the simulated hydrographs against USGS streamflow gauge observations. The results prove the capability of the developed model in simulating reasonably accurate outflows from dams and will be presented at the meeting.

  11. Assessment of a Hybrid Continuous/Discontinuous Galerkin Finite Element Code for Geothermal Reservoir Simulations

    NASA Astrophysics Data System (ADS)

    Xia, Yidong; Podgorney, Robert; Huang, Hai

    2017-03-01

    FALCON (Fracturing And Liquid CONvection) is a hybrid continuous/discontinuous Galerkin finite element geothermal reservoir simulation code based on the MOOSE (Multiphysics Object-Oriented Simulation Environment) framework being developed and used for multiphysics applications. In the present work, a suite of verification and validation (V&V) test problems for FALCON was defined to meet the design requirements, and solved to the interests of enhanced geothermal system modeling and simulation. The intent for this test problem suite is to provide baseline comparison data that demonstrates the performance of FALCON solution methods. The test problems vary in complexity from a single mechanical or thermal process, to coupled thermo-hydro-mechanical processes in geological porous medium. Numerical results obtained by FALCON agreed well with either the available analytical solutions or experimental data, indicating the verified and validated implementation of these capabilities in FALCON. Whenever possible, some form of solution verification has been attempted to identify sensitivities in the solution methods, and suggest best practices when using the FALCON code.

  12. Coupling of geochemical and multiphase flow processes for validation of the MUFITS reservoir simulator against TOUGHREACT

    NASA Astrophysics Data System (ADS)

    De Lucia, Marco; Kempka, Thomas; Afanasyev, Andrey; Melnik, Oleg; Kühn, Michael

    2016-04-01

    Coupled reactive transport simulations, especially in heterogeneous settings considering multiphase flow, are extremely time consuming and suffer from significant numerical issues compared to purely hydrodynamic simulations. This represents a major hurdle in the assessment of geological subsurface utilization, since it constrains the practical application of reactive transport modelling to coarse spatial discretization or oversimplified geological settings. In order to overcome such limitations, De Lucia et al. [1] developed and validated a one-way coupling approach between geochemistry and hydrodynamics, which is particularly well suited for CO2 storage simulations, while being of general validity. In the present study, the models used for the validation of the one-way coupling approach introduced by De Lucia et al. (2015), and originally performed with the TOUGHREACT simulator, are transferred to and benchmarked against the multiphase reservoir simulator MUFITS [2]. The geological model is loosely inspired by an existing CO2 storage site. Its grid comprises 2,950 elements enclosed in a single layer, but reflecting a realistic three-dimensional anticline geometry. For the purpose of this comparison, homogeneous and heterogeneous scenarios in terms of porosity and permeability were investigated. In both cases, the results of the MUFITS simulator are in excellent agreement with those produced with the fully-coupled TOUGHREACT simulator, while profiting from significantly higher computational performance. This study demonstrates how a computationally efficient simulator such as MUFITS can be successfully included in a coupled process simulation framework, and also suggests ameliorations and specific strategies for the coupling of chemical processes with hydrodynamics and heat transport, aiming at tackling geoscientific problems beyond the storage of CO2. References [1] De Lucia, M., Kempka, T., and Kühn, M. A coupling alternative to reactive transport simulations

  13. An Exact Solution to the Draining Reservoir Problem of the Incompressible and Non-Viscous Liquid

    ERIC Educational Resources Information Center

    Hong, Seok-In

    2009-01-01

    The exact expressions for the drain time and the height, velocity and acceleration of the free surface are found for the draining reservoir problem of the incompressible and non-viscous liquid. Contrary to the conventional approximate results, they correctly describe the initial time dependence of the liquid velocity and acceleration. Torricelli's…

  14. Universal approximators for multi-objective direct policy search in water reservoir management problems: a comparative analysis

    NASA Astrophysics Data System (ADS)

    Giuliani, Matteo; Mason, Emanuele; Castelletti, Andrea; Pianosi, Francesca

    2014-05-01

    The optimal operation of water resources systems is a wide and challenging problem due to non-linearities in the model and the objectives, high dimensional state-control space, and strong uncertainties in the hydroclimatic regimes. The application of classical optimization techniques (e.g., SDP, Q-learning, gradient descent-based algorithms) is strongly limited by the dimensionality of the system and by the presence of multiple, conflicting objectives. This study presents a novel approach which combines Direct Policy Search (DPS) and Multi-Objective Evolutionary Algorithms (MOEAs) to solve high-dimensional state and control space problems involving multiple objectives. DPS, also known as parameterization-simulation-optimization in the water resources literature, is a simulation-based approach where the reservoir operating policy is first parameterized within a given family of functions and, then, the parameters optimized with respect to the objectives of the management problem. The selection of a suitable class of functions to which the operating policy belong to is a key step, as it might restrict the search for the optimal policy to a subspace of the decision space that does not include the optimal solution. In the water reservoir literature, a number of classes have been proposed. However, many of these rules are based largely on empirical or experimental successes and they were designed mostly via simulation and for single-purpose reservoirs. In a multi-objective context similar rules can not easily inferred from the experience and the use of universal function approximators is generally preferred. In this work, we comparatively analyze two among the most common universal approximators: artificial neural networks (ANN) and radial basis functions (RBF) under different problem settings to estimate their scalability and flexibility in dealing with more and more complex problems. The multi-purpose HoaBinh water reservoir in Vietnam, accounting for hydropower

  15. Fishery management problems and possibilities on large southeastern reservoirs

    USGS Publications Warehouse

    Parsons, John W.

    1958-01-01

    In recognition of these problems, the development and application of sound management procedures may be accomplished by controlling species composition and availability of fish through water level control, timber clearing, application of selective toxicants, commercial fishing, introduction of new fish species, and the management of tailwaters and tributaries. Extended research and interagency cooperation are necessary to properly develop and apply sound management. Promotion of angling and regulation of the fishery may best be realized by providing adequate fishing facilities, elimination of certain restricted areas, and in some cases revision of laws and regulations. Biologists must not only meet the present demands for improved sport fishing but must also balance fish yield by increasing the use of food fish by sport and commercial operations.

  16. Using microstructure observations to quantify fracture properties and improve reservoir simulations. Final report, September 1998

    SciTech Connect

    Laubach, S.E.; Marrett, R.; Rossen, W.; Olson, J.; Lake, L.; Ortega, O.; Gu, Y.; Reed, R.

    1999-01-01

    The research for this project provides new technology to understand and successfully characterize, predict, and simulate reservoir-scale fractures. Such fractures have worldwide importance because of their influence on successful extraction of resources. The scope of this project includes creation and testing of new methods to measure, interpret, and simulate reservoir fractures that overcome the challenge of inadequate sampling. The key to these methods is the use of microstructures as guides to the attributes of the large fractures that control reservoir behavior. One accomplishment of the project research is a demonstration that these microstructures can be reliably and inexpensively sampled. Specific goals of this project were to: create and test new methods of measuring attributes of reservoir-scale fractures, particularly as fluid conduits, and test the methods on samples from reservoirs; extrapolate structural attributes to the reservoir scale through rigorous mathematical techniques and help build accurate and useful 3-D models of the interwell region; and design new ways to incorporate geological and geophysical information into reservoir simulation and verify the accuracy by comparison with production data. New analytical methods developed in the project are leading to a more realistic characterization of fractured reservoir rocks. Testing diagnostic and predictive approaches was an integral part of the research, and several tests were successfully completed.

  17. Simulations of Flow Circulations and Atrazine Concentrations in a Midwest U.S. Reservoir

    NASA Astrophysics Data System (ADS)

    Zhao, Xianggui; Gu, Roy R.; Guo, Chuling; Wang, Kui; Li, Shijie

    Atrazine is the most commonly used herbicide in the spring for pre-emergent weed control in the corn cropping area in the Midwestern United States. A frequent high level of herbicide concentrations in reservoirs is a great concern for public health and aquatic ecosystems. In this study, a two-dimensional hydrodynamics and toxic contaminant transport model was applied to Saylorville Reservoir, Iowa, USA. The model simulates physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical. Model results were validated by measured temperatures and atrazine concentrations. Simulated flow velocities, water temperatures, and chemical concentrations demonstrated that the spatial variation of atrazine concentrations was largely affected by seasonal flow circulation patterns in the reservoir. In particular, the simulated fate and transport of atrazine showed the effect of flow circulation on spatial distribution of atrazine during summer months as the river flow formed an underflow within the reservoir and resulted in greater concentrations near the surface of the reservoir. Atrazine concentrations in the reservoir peaked around the end of May and early June. A thorough understanding of the fate and transport of atrazine in the reservoir can assist in developing operation and pollution prevention strategies with respect to timing, amount, and depth of withdrawal. The responses of atrazine transport to various boundary conditions provide useful information in assessing environmental impact of alternative upstream watershed management practices on the quality of reservoir water.

  18. Modeling dolomitized carbonate-ramp reservoirs: A case study of the Seminole San Andres unit. Part 2 -- Seismic modeling, reservoir geostatistics, and reservoir simulation

    SciTech Connect

    Wang, F.P.; Dai, J.; Kerans, C.

    1998-11-01

    In part 1 of this paper, the authors discussed the rock-fabric/petrophysical classes for dolomitized carbonate-ramp rocks, the effects of rock fabric and pore type on petrophysical properties, petrophysical models for analyzing wireline logs, the critical scales for defining geologic framework, and 3-D geologic modeling. Part 2 focuses on geophysical and engineering characterizations, including seismic modeling, reservoir geostatistics, stochastic modeling, and reservoir simulation. Synthetic seismograms of 30 to 200 Hz were generated to study the level of seismic resolution required to capture the high-frequency geologic features in dolomitized carbonate-ramp reservoirs. Outcrop data were collected to investigate effects of sampling interval and scale-up of block size on geostatistical parameters. Semivariogram analysis of outcrop data showed that the sill of log permeability decreases and the correlation length increases with an increase of horizontal block size. Permeability models were generated using conventional linear interpolation, stochastic realizations without stratigraphic constraints, and stochastic realizations with stratigraphic constraints. Simulations of a fine-scale Lawyer Canyon outcrop model were used to study the factors affecting waterflooding performance. Simulation results show that waterflooding performance depends strongly on the geometry and stacking pattern of the rock-fabric units and on the location of production and injection wells.

  19. Analysis of formation pressure test results in the Mount Elbert methane hydrate reservoir through numerical simulation

    USGS Publications Warehouse

    Kurihara, M.; Sato, A.; Funatsu, K.; Ouchi, H.; Masuda, Y.; Narita, H.; Collett, T.S.

    2011-01-01

    Targeting the methane hydrate (MH) bearing units C and D at the Mount Elbert prospect on the Alaska North Slope, four MDT (Modular Dynamic Formation Tester) tests were conducted in February 2007. The C2 MDT test was selected for history matching simulation in the MH Simulator Code Comparison Study. Through history matching simulation, the physical and chemical properties of the unit C were adjusted, which suggested the most likely reservoir properties of this unit. Based on these properties thus tuned, the numerical models replicating "Mount Elbert C2 zone like reservoir" "PBU L-Pad like reservoir" and "PBU L-Pad down dip like reservoir" were constructed. The long term production performances of wells in these reservoirs were then forecasted assuming the MH dissociation and production by the methods of depressurization, combination of depressurization and wellbore heating, and hot water huff and puff. The predicted cumulative gas production ranges from 2.16??106m3/well to 8.22??108m3/well depending mainly on the initial temperature of the reservoir and on the production method.This paper describes the details of modeling and history matching simulation. This paper also presents the results of the examinations on the effects of reservoir properties on MH dissociation and production performances under the application of the depressurization and thermal methods. ?? 2010 Elsevier Ltd.

  20. Simulated Occupational Problems in Encouraging Career Exploration.

    ERIC Educational Resources Information Center

    Johnson, Richard G.

    The present study attempted to determine the optimal difficulty level of some occupational problems for students with varying interests and ability levels. Some 288 high school boys were presented with simulated vocational problems in sales, medical laboratory technology, and x-ray technology. The criterion for a successful performance was set at…

  1. Vortex formation in coalescence of droplets with a reservoir using molecular dynamics simulations.

    PubMed

    Taherian, Fereshte; Marcon, Valentina; Bonaccurso, Elmar; van der Vegt, Nico F A

    2016-10-01

    The flow patterns generated by the coalescence of aqueous ethanol droplets with a water reservoir are investigated using molecular dynamics simulations. The influence of surface tension gradient, which leads to the spreading of the droplet along the liquid-vapor interface of the reservoir, is studied by changing the ethanol concentration of the droplet. The internal circulation (vortex strength) of the droplet and the reservoir are analyzed separately. Simulation results reveal the formation of swirling flows within the droplet at early times when the radius of the coalescence neck due to the capillary forces increases rapidly with time. The vortex strength is found to be higher at lower concentrations of ethanol (higher liquid-vapor surface tension of the droplet), where the driving force for the contact line movement (capillary force) is stronger. The circulation diminishes by moving the center of mass of the droplet toward the reservoir. The lower surface tension of the droplet compared to the reservoir leads to surface tension gradient driven flow, which transports the droplet molecules along the liquid-vapor interface of the reservoir. Such a flow motion results in the generation of convective flows in the underlying water, which forms swirling flows within the reservoir. Therefore, the vortex strength of the reservoir is higher at higher ethanol concentrations of the droplet. The reservoir circulation decays to zero as soon as the ethanol concentration becomes homogeneous along the interface of the pool. The time evolution of circulation within the droplet and the reservoir are correlated with the center of mass motion of the droplet toward the surface, the time variation of the precursor film radius and the dynamic surface tension of the reservoir.

  2. Solid hydrocarbon: a migration-of-fines problem in carbonate reservoirs

    SciTech Connect

    Lomando, A.J.

    1986-05-01

    The most familiar example of a migration-of-fines problem is authigenic kaolinite, which can detach, migrate through a pore system, and bridge pore throats, thus reducing permeability. under certain conditions, a similar problem is caused by solid hydrocarbon, independent of a mode of origin, which has precipitated in carbonate pore systems. Cores from several reservoirs in the Lower Cretaceous of east Texas were used as the data base in this study. Three morphotypes of solid hydrocarbon have been identified from thin-section and scanning electron microscope observations: droplets, peanut brittle, and carpets. Droplets are small, individual, rounded particles scattered on pore walls. Peanut brittle ranges from a continuous to discontinuous thin coating with random rounded lumps that probably have droplet precursors. Carpets are thick, continuous coatings and, at the extreme, can effectively occlude whole pores. Initially, solid hydrocarbon reduces permeability without necessarily decreasing porosity significantly. Likewise, solid hydrocarbon cannot be detected directly from wireline logs. Acidizing to enhance communication to the well bore is a common completion procedure in limestone and calcareous sandstone reservoirs. In reservoirs containing solid hydrocarbon, acid etches the substrate and releases solid hydrocarbon, which migrates in the pore system and bridges pore throats. Differential well-bore pressure also may cause solid hydrocarbon to migrate. Therefore, wettability, which controls hydrocarbon adhesion to the pore walls, and the dominant morphotype are important factors in the extent of reservoir damage.

  3. Comparisons of Simulated Hydrodynamics and Water Quality for Projected Demands in 2046, Pueblo Reservoir, Southeastern Colorado

    USGS Publications Warehouse

    Ortiz, Roderick F.; Galloway, Joel M.; Miller, Lisa D.; Mau, David P.

    2008-01-01

    Pueblo Reservoir is one of southeastern Colorado's most valuable water resources. The reservoir provides irrigation, municipal, and industrial water to various entities throughout the region. The reservoir also provides flood control, recreational activities, sport fishing, and wildlife enhancement to the region. The Bureau of Reclamation is working to meet its goal to issue a Final Environmental Impact Statement (EIS) on the Southern Delivery System project (SDS). SDS is a regional water-delivery project that has been proposed to provide a safe, reliable, and sustainable water supply through the foreseeable future (2046) for Colorado Springs, Fountain, Security, and Pueblo West. Discussions with the Bureau of Reclamation and the U.S. Geological Survey led to a cooperative agreement to simulate the hydrodynamics and water quality of Pueblo Reservoir. This work has been completed and described in a previously published report, U.S. Geological Survey Scientific Investigations Report 2008-5056. Additionally, there was a need to make comparisons of simulated hydrodynamics and water quality for projected demands associated with the various EIS alternatives and plans by Pueblo West to discharge treated water into the reservoir. Plans by Pueblo West are fully independent of the SDS project. This report compares simulated hydrodynamics and water quality for projected demands in Pueblo Reservoir resulting from changes in inflow and water quality entering the reservoir, and from changes to withdrawals from the reservoir as projected for the year 2046. Four of the seven EIS alternatives were selected for scenario simulations. The four U.S. Geological Survey simulation scenarios were the No Action scenario (EIS Alternative 1), the Downstream Diversion scenario (EIS Alternative 2), the Upstream Return-Flow scenario (EIS Alternative 4), and the Upstream Diversion scenario (EIS Alternative 7). Additionally, the results of an Existing Conditions scenario (water years 2000 through

  4. Quantum Simulation of the Factorization Problem

    NASA Astrophysics Data System (ADS)

    Rosales, Jose Luis; Martin, Vicente

    2016-11-01

    Feynman's prescription for a quantum simulator was to find a Hamitonian for a system that could serve as a computer. The Pólya-Hilbert conjecture proposed the demonstration of Riemann's hypothesis through the spectral decomposition of Hermitian operators. Here we study the problem of decomposing a number into its prime factors, N =x y , using such a simulator. First, we derive the Hamiltonian of the physical system that simulates a new arithmetic function formulated for the factorization problem that represents the energy of the computer. This function rests alone on the primes below √{N }. We exactly solve the spectrum of the quantum system without resorting to any external ad hoc conditions, also showing that it obtains, for x ≪√{N }, a prediction of the prime counting function that is almost identical to Riemann's R (x ) function. It has no counterpart in analytic number theory, and its derivation is a consequence of the quantum theory of the simulator alone.

  5. Ultrasonic and numerical modeling of reflections from simulated fractured reservoirs

    SciTech Connect

    Stephen, T.; Zhu, Xiang,

    1997-10-01

    In order to develop modeling techniques for the characterization of fracture properties in tight gas sands from surface seismic reflection data we examine seismic waves scattered from anisotropic heterogeneity with laboratory data and numerical modeling. Laboratory models representing features of a fractured reservoir were constructed using Phenolite embedded in a Lucite background, and seismic surveys were gathered over these models. In parallel with laboratory measurement, finite-difference modeling of reflections from a fractured medium were carried out. Fracture zone properties were calculated using an effective medium theory, the variation of fracture density produced a heterogeneous medium. The heterogeneity was modeled with a stochastic process, characterized by a probability density function and an auto-correlation function. Results from both modeling efforts show that prestacked AVO data can contain important information describing reservoir heterogeneity.

  6. Numerical simulation of fluid implementing heat transfer in naturally fractured geothermal reservoir with DFN method

    NASA Astrophysics Data System (ADS)

    Lee, T.; Kim, K.; Lee, K.; Lee, H.; Lee, W.

    2015-12-01

    Natural fractures have an effect on the fluid flow and heat transfer in the naturally fractured geothermal reservoir. However, most of the previous works in this area assumed that reservoir systems are continuum model whether it is single continuum or dual continuum. Moreover, some people have studied without continuum model but, it was just pipeline model. In this paper, we developed a generalized discrete fracture network (DFN) geothermal reservoir simulator. In the model, 2D flow is possible within a rectangular fracture, which is important in thick naturally fractured reservoirs. The DFN model developed in this study was validated for two synthetic fracture systems using a commercial thermal model, TETRAD. Comparison results showed an excellent matching between both models. However, this model is only fracture model and it can't calculate simulation of fluid flow and heat transfer in matrix. Therefore, matrix flow model will be added to this model.

  7. Some mismatches occurred when simulating fractured reservoirs as homogeneous porous media

    SciTech Connect

    Mario Cesar Suarez Arriaga; Fernando Samaniego V.; Fernando Rodriguez

    1996-01-24

    The understanding of transport processes that occur in naturally fractured geothermal systems is far from being complete. Often, evaluation and numerical simulations of fractured geothermal reservoirs, are carried out by assuming equivalent porous media and homogeneous petrophysical properties within big matrix blocks. The purpose of this paper, is to present a comparison between results obtained from numerical studies of a naturally fractured reservoir treated as a simple porous medium and the simulation of some real aspects of the fractured reservoir. A general conclusion outlines the great practical importance of considering even approximately, the true nature of such systems. Our results show that the homogeneous simplified evaluation of the energy resource in a fractured system, could result in unrealistic estimates of the reservoir capacity to generate electricity.

  8. Numerical simulation of heterogeneous fractured gas reservoir systems with turbulence and closure stress effects

    SciTech Connect

    Allam, A.M.; Crichlow, H.B.; Soliman, M.Y.

    1981-01-01

    A numerical technique for analyzing the behavior of a fractured gas reservoir system is presented. The reservoir is simulated by a fully implicit three-dimensional model that incorporates the effects of turbulent flow and closure stress in a finite conductivity fracture. The model utilizes the real gas pseudo-pressure, two-point upstream transmissibilities and a stable iterative process based on a sparse matrix approach to solving the equation systems. This paper presents a description of the model and applications to various reservoirs to illustrate the effects of fracture heights, turbulence and closure pressure on well performance. 16 refs.

  9. Waterflooding simulation of reservoir containing horizontal well stimulated by multistage hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Mazo, A. B.; Khamidullin, M. R.; Potashev, K. A.

    2016-11-01

    The article presents a three-dimensional mathematical model for two-phase fluid flow near a multistage hydraulically fractured horizontal well (MSHFHW). The flow in the reservoir and in the fractures is simulated separately, and the flow rate is governed by Darcy's law. Finite volume method is used for spatial approximation. The obtained systems of linear equations for pressure in the reservoir and in the fractures are solved simultaneously, which allows us to avoid using iterative process for solution adjustment both in the fractures and the reservoir. Saturation is calculated by the implicit adaptive scheme AIM.

  10. Simulators' validation study: Problem solution logic

    NASA Technical Reports Server (NTRS)

    Schoultz, M. B.

    1974-01-01

    A study was conducted to validate the ground based simulators used for aircraft environment in ride-quality research. The logic to the approach for solving this problem is developed. The overall problem solution flow chart is presented. The factors which could influence the human response to the environment on board the aircraft are analyzed. The mathematical models used in the study are explained. The steps which were followed in conducting the validation tests are outlined.

  11. Advanced Techniques for Reservoir Simulation and Modeling of Non-Conventional Wells

    SciTech Connect

    Durlofsky, Louis J.; Aziz, Khalid

    2001-08-23

    Research results for the second year of this project on the development of improved modeling techniques for non-conventional (e.g., horizontal, deviated or multilateral) wells were presented. The overall program entails the development of enhanced well modeling and general simulation capabilities. A general formulation for black-oil and compositional reservoir simulation was presented.

  12. Application of advanced reservoir characterization, simulation and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, West Texas (Delaware Basin). Annual report

    SciTech Connect

    Dutton, S.P.; Asquith, G.B.; Barton, M.D.; Cole, A.G.; Gogas, J.; Malik, M.A.; Clift, S.J.; Guzman, J.I.

    1997-11-01

    The objective of this project is to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost-effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. This project involves reservoir characterization of two Late Permian slope and basin clastic reservoirs in the Delaware Basin, West Texas, followed by a field demonstration in one of the fields. The fields being investigated are Geraldine Ford and Ford West fields in Reeves and Culberson Counties, Texas. Project objectives are divided into two major phases, reservoir characterization and implementation. The objectives of the reservoir characterization phase of the project were to provide a detailed understanding of the architecture and heterogeneity of the two fields, the Ford Geraldine unit and Ford West field. Reservoir characterization utilized 3-D seismic data, high-resolution sequence stratigraphy, subsurface field studies, outcrop characterization, and other techniques. Once reservoir characterized was completed, a pilot area of approximately 1 mi{sup 2} at the northern end of the Ford Geraldine unit was chosen for reservoir simulation. This report summarizes the results of the second year of reservoir characterization.

  13. One-dimensional simulation of stratification and dissolved oxygen in McCook Reservoir, Illinois

    USGS Publications Warehouse

    Robertson, Dale M.

    2000-01-01

    As part of the Chicagoland Underflow Plan/Tunnel and Reservoir Plan, the U.S. Army Corps of Engineers, Chicago District, plans to build McCook Reservoir.a flood-control reservoir to store combined stormwater and raw sewage (combined sewage). To prevent the combined sewage in the reservoir from becoming anoxic and producing hydrogen sulfide gas, a coarse-bubble aeration system will be designed and installed on the basis of results from CUP 0-D, a zero-dimensional model, and MAC3D, a three-dimensional model. Two inherent assumptions in the application of MAC3D are that density stratification in the simulated water body is minimal or not present and that surface heat transfers are unimportant and, therefore, may be neglected. To test these assumptions, the previously tested, one-dimensional Dynamic Lake Model (DLM) was used to simulate changes in temperature and dissolved oxygen in the reservoir after a 1-in-100-year event. Results from model simulations indicate that the assumptions made in MAC3D application are valid as long as the aeration system, with an air-flow rate of 1.2 cubic meters per second or more, is operated while the combined sewage is stored in the reservoir. Results also indicate that the high biochemical oxygen demand of the combined sewage will quickly consume the dissolved oxygen stored in the reservoir and the dissolved oxygen transferred through the surface of the reservoir; therefore, oxygen must be supplied by either the rising bubbles of the aeration system (a process not incorporated in DLM) or some other technique to prevent anoxia.

  14. Simulation of irreversible rock compaction effects on geopressured reservoir response: Topical report

    SciTech Connect

    Riney, T.D.

    1986-12-01

    A series of calculations are presented which quantitatively demonstrate the effects of nonlinear stress-deformation properties on the behavior of geopressured reservoirs. The range of stress-deformation parameters considered is based on information available from laboratory rock mechanics tests performed at the University of Texas at Austin and at Terra Tek, Inc. on cores recovered from geopressured wells. The effects of irreversible formation rock compaction, associated permeability reduction, and repetitive load/unload cycling are considered. The formation rock and geopressured brine properties are incorporated into an existing reservoir simulator using a bilinear model for the irreversible compaction process. Pressure drawdown and buildup testing of a well producing from the geopressured formation is simulated for a suite of calculations covering the range of formation parameters. The results are presented and discussed in terms of the inference (e.g., permeability and reservoir volume) that would be drawn from the simulated test data by an analyst using conventional methods.

  15. Visualization of reservoir simulation data with an immersive virtual reality system

    SciTech Connect

    Williams, B.K.

    1996-10-01

    This paper discusses an investigation into the use of an immersive virtual reality (VR) system to visualize reservoir simulation output data. The hardware and software configurations of the test-immersive VR system are described and compared to a nonimmersive VR system and to an existing workstation screen-based visualization system. The structure of 3D reservoir simulation data and the actions to be performed on the data within the VR system are discussed. The subjective results of the investigation are then presented, followed by a discussion of possible future work.

  16. Minimization of Gibbs free energy in compositional reservoir simulation

    SciTech Connect

    Trungenstein, J.A.

    1985-02-01

    This paper describes the formulation of vapor-liquid phase equilibrium as a linearly constrained minimization problem. It also describes a second minimization problem designed to test for local phase stability. Vectorized unconstrained minimization techniques can be used to solve this pair of constrained minimization problems. The methods of this paper are applied to liquid-vapor equilibria for mixtures both far from and near to the phase boundary. Significant improvements over the standard successive substitution algorithm are demonstrated.

  17. Simulation of Hydrodynamics at Stratified Reservoirs Using a Staged Modeling Approach

    SciTech Connect

    Khangaonkar, Tarang P.; Yang, Zhaoqing; Paik, Joongcheol; Sotiropoulos, Fotis

    2008-10-01

    Hydropower reservoirs impounded by high-head dams exhibit complex circulation that confuses the downstream migrating salmon and limits successful collection and passage of fish. Fish passage engineers attempt to modify the hydrothermal behavior at reservoirs through structural and operational modifications and often use hydrodynamic simulations to guide their actions. Simulation of key hydrothermal processes such as (a) development of a stable two-layer stratified system, (b) density-driven currents over a reservoir length scale, and (c) discharge hydraulics near the power generation and fish collection intakes requires highly specialized models applied at differing temporal and spatial scales. A staged modeling approach is presented that uses external coupling of models at varying temporal scales and spatial resolution to simulate the entire hydraulic regime from the mouth of the reservoir at the upstream end to the discharge at the dam. The staged modeling approach is illustrated using a case study where structural modifications were evaluated to improve reservoir stratification and density-driven currents. The model results provided input and valuable insight in the development of a new structure design and configuration for effective fish collection near the forebay of a high-head dam.

  18. Simulation of water temperature in two reservoirs with Delft3d

    NASA Astrophysics Data System (ADS)

    Yang, J. Y.; Zhou, L. Y.

    2016-08-01

    The proposeled Guanjingkou and Fengdou reservoir will be constructed at Chongqing city and Muling city in China respectively. The water temperature in the reservoir, in the downstream, and the aquatic ecosystem would be altered by the construction of the reservoirs. This paper simulates the water temperature in the two reservoirs by using the Delft3d z-layer model, which uses the fixed elevation for layers. According to the simulation results, the temperature profile in the reservoirs can be divided into three layers: the upmost epilimnion layer, the beneathed thermocline layer, and the constant tepmerature layer at bottom. The temperature effects can be reduced by measurements of stoplogs gates and mutiple gates, respectively. Based on the simulation results in the wet, nomal, and dry year, the temperature of water released from the stoplogs gates at Guanjingkou reservior can be respectively increased by 5.7°C, 6.8°C, 9.6°C, and 5.5°C in the irrigation season from May to August. The temperature of water released from the mutiple gates at Fengdou reservior can be respectively increased by 7.7 °C, 1.9 °C, 9.5 °C, and 10.1 °C from May to August. The negative impacts from the water with lower temperature on the related ecosystem can be significently alleviated.

  19. Problems related to water quality and algal control in Lopez Reservoir, San Luis Obispo County, California

    USGS Publications Warehouse

    Fuller, Richard H.; Averett, Robert C.; Hines, Walter G.

    1975-01-01

    A study to determine the present enrichment status of Liopez Reservoir in San Luis Obispo county, California, and to evaluate copper sulfate algal treatment found that stratification in the reservoir regulates nutrient release and that algal control has been ineffective. Nuisance algal blooms, particularly from March to June, have been a problem in the warm multipurpose reservoir since it was initially filled following intense storms in 1968-69. The cyanophyte Anabaena unispora has been dominant; cospecies are the diatoms Stephanodiscus astraea and Cyclotella operculata, and the chlorophytes Pediastrum deplex and Sphaerocystis schroeteri. During an A. unispora bloom in May 1972 the total lake surface cell count was nearly 100,000 cells/ml. Thermal stratification from late spring through autumn results in oxygen deficiency in the hypolimnion and metalimnion caused by bacterial oxidation of organic detritus. The anaerobic conditions favor chemical reduction of organic matter, which constitute 10-14% of the sediment. As algae die, sink to the bottom, and decompose, nutrients are released to the hypolimnion , and with the autumn overturn are spread to the epilimnion. Algal blooms not only hamper recreation, but through depletion of dissolved oxygen in the epilimnion may have caused periodic fishkills. Copper sulfate mixed with sodium citrate and applied at 1.10-1.73 lbs/acre has not significantly reduced algal growth; a method for determining correct dosage is presented. (Lynch-Wisconsin)

  20. Evaluation of Gas Production Potential of Hydrate Deposits in Alaska North Slope using Reservoir Simulations

    NASA Astrophysics Data System (ADS)

    Nandanwar, M.; Anderson, B. J.

    2015-12-01

    Over the past few decades, the recognition of the importance of gas hydrates as a potential energy resource has led to more and more exploration of gas hydrate as unconventional source of energy. In 2002, U.S. Geological Survey (USGS) started an assessment to conduct a geology-based analysis of the occurrences of gas hydrates within northern Alaska. As a result of this assessment, many potential gas hydrate prospects were identified in the eastern National Petroleum Reserve Alaska (NPRA) region of Alaska North Slope (ANS) with total gas in-place of about 2 trillion cubic feet. In absence of any field test, reservoir simulation is a powerful tool to predict the behavior of the hydrate reservoir and the amount of gas that can be technically recovered using best suitable gas recovery technique. This work focuses on the advanced evaluation of the gas production potential of hydrate accumulation in Sunlight Peak - one of the promising hydrate fields in eastern NPRA region using reservoir simulations approach, as a part of the USGS gas hydrate development Life Cycle Assessment program. The main objective of this work is to develop a field scale reservoir model that fully describes the production design and the response of hydrate field. Due to the insufficient data available for this field, the distribution of the reservoir properties (such as porosity, permeability and hydrate saturation) are approximated by correlating the data from Mount Elbert hydrate field to obtain a fully heterogeneous 3D reservoir model. CMG STARS is used as a simulation tool to model multiphase, multicomponent fluid flow and heat transfer in which an equilibrium model of hydrate dissociation was used. Production of the gas from the reservoir is carried out for a period of 30 years using depressurization gas recovery technique. The results in terms of gas and water rate profiles are obtained and the response of the reservoir to pressure and temperature changes due to depressurization and hydrate

  1. Tight gas reservoir simulation: Modeling discrete irregular strata-bound fracture network flow, including dynamic recharge from the matrix

    SciTech Connect

    McKoy, M.L., Sams, W.N.

    1997-10-01

    The US Department of Energy, Federal Energy Technology Center, has sponsored a project to simulate the behavior of tight, fractured, strata-bound gas reservoirs that arise from irregular discontinuous, or clustered networks of fractures. New FORTRAN codes have been developed to generate fracture networks, or simulate reservoir drainage/recharge, and to plot the fracture networks and reservoirs pressures. Ancillary codes assist with raw data analysis.

  2. Corticostriatal response selection in sentence production: Insights from neural network simulation with reservoir computing.

    PubMed

    Hinaut, Xavier; Lance, Florian; Droin, Colas; Petit, Maxime; Pointeau, Gregoire; Dominey, Peter Ford

    2015-11-01

    Language production requires selection of the appropriate sentence structure to accommodate the communication goal of the speaker - the transmission of a particular meaning. Here we consider event meanings, in terms of predicates and thematic roles, and we address the problem that a given event can be described from multiple perspectives, which poses a problem of response selection. We present a model of response selection in sentence production that is inspired by the primate corticostriatal system. The model is implemented in the context of reservoir computing where the reservoir - a recurrent neural network with fixed connections - corresponds to cortex, and the readout corresponds to the striatum. We demonstrate robust learning, and generalization properties of the model, and demonstrate its cross linguistic capabilities in English and Japanese. The results contribute to the argument that the corticostriatal system plays a role in response selection in language production, and to the stance that reservoir computing is a valid potential model of corticostriatal processing.

  3. Simulation studies to evaluate the effect of fracture closure on the performance of fractured reservoirs; Final report

    SciTech Connect

    Howrie, I.; Dauben, D.

    1994-03-01

    A three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The overall objectives of the study were to: (1) evaluate the reservoir conditions for which fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. The evaluations of reservoir performance were made by a modern dual porosity simulator, TETRAD. This simulator treats both porosity and permeability as functions of pore pressure. The Austin Chalk in the Pearsall Field in of South Texas was selected as the prototype fractured reservoir for this work. During the first year, simulations of vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure change. Sensitivity runs indicated that the simulator was predicting the effects of critical reservoir parameters in a logical and consistent manner. The results confirmed that horizontal wells could increase both rate of oil recovery and total oil recovery from naturally fractured reservoirs. In the second year, the performance of the same vertical and horizontal wells was reevaluated with fracture permeability treated as a function of reservoir pressure. To investigate sensitivity to in situ stress, differing loading conditions were assumed. Simulated natural depletions confirm that pressure sensitive fractures degrade well performance. The severity of degradation worsens when the initial reservoir pressure approaches the average stress condition of the reservoir, such as occurs in over pressured reservoirs. Simulations with water injection indicate that degradation of permeability can be counteracted when reservoir pressure is maintained and oil recovery can be increased when reservoir properties are favorable.

  4. A combination of streamtube and geostatical simulation methodologies for the study of large oil reservoirs

    SciTech Connect

    Chakravarty, A.; Emanuel, A.S.; Bernath, J.A.

    1997-08-01

    The application of streamtube models for reservoir simulation has an extensive history in the oil industry. Although these models are strictly applicable only to fields under voidage balance, they have proved to be useful in a large number of fields provided that there is no solution gas evolution and production. These models combine the benefit of very fast computational time with the practical ability to model a large reservoir over the course of its history. These models do not, however, directly incorporate the detailed geological information that recent experience has taught is important. This paper presents a technique for mapping the saturation information contained in a history matched streamtube model onto a detailed geostatistically derived finite difference grid. With this technique, the saturation information in a streamtube model, data that is actually statistical in nature, can be identified with actual physical locations in a field and a picture of the remaining oil saturation can be determined. Alternatively, the streamtube model can be used to simulate the early development history of a field and the saturation data then used to initialize detailed late time finite difference models. The proposed method is presented through an example application to the Ninian reservoir. This reservoir, located in the North Sea (UK), is a heterogeneous sandstone characterized by a line drive waterflood, with about 160 wells, and a 16 year history. The reservoir was satisfactorily history matched and mapped for remaining oil saturation. A comparison to 3-D seismic survey and recently drilled wells have provided preliminary verification.

  5. Quantum simulation of dissipative processes without reservoir engineering

    SciTech Connect

    Di Candia, R.; Pedernales, J. S.; del Campo, A.; Solano, E.; Casanova, J.

    2015-05-29

    We present a quantum algorithm to simulate general finite dimensional Lindblad master equations without the requirement of engineering the system-environment interactions. The proposed method is able to simulate both Markovian and non-Markovian quantum dynamics. It consists in the quantum computation of the dissipative corrections to the unitary evolution of the system of interest, via the reconstruction of the response functions associated with the Lindblad operators. Our approach is equally applicable to dynamics generated by effectively non-Hermitian Hamiltonians. We confirm the quality of our method providing specific error bounds that quantify its accuracy.

  6. Quantum Simulation of Dissipative Processes without Reservoir Engineering

    PubMed Central

    Di Candia, R.; Pedernales, J. S.; del Campo, A.; Solano, E.; Casanova, J.

    2015-01-01

    We present a quantum algorithm to simulate general finite dimensional Lindblad master equations without the requirement of engineering the system-environment interactions. The proposed method is able to simulate both Markovian and non-Markovian quantum dynamics. It consists in the quantum computation of the dissipative corrections to the unitary evolution of the system of interest, via the reconstruction of the response functions associated with the Lindblad operators. Our approach is equally applicable to dynamics generated by effectively non-Hermitian Hamiltonians. We confirm the quality of our method providing specific error bounds that quantify its accuracy. PMID:26024437

  7. Problem reporting management system performance simulation

    NASA Technical Reports Server (NTRS)

    Vannatta, David S.

    1993-01-01

    This paper proposes the Problem Reporting Management System (PRMS) model as an effective discrete simulation tool that determines the risks involved during the development phase of a Trouble Tracking Reporting Data Base replacement system. The model considers the type of equipment and networks which will be used in the replacement system as well as varying user loads, size of the database, and expected operational availability. The paper discusses the dynamics, stability, and application of the PRMS and addresses suggested concepts to enhance the service performance and enrich them.

  8. Motor operated valves problems tests and simulations

    SciTech Connect

    Pinier, D.; Haas, J.L.

    1996-12-01

    An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a {open_quotes}boiler{close_quotes} effect: determination of the necessary modifications: development and testing of anti-boiler effect systems.

  9. BM platform, B Field, Offshore Northwest Java: A case history of multi-disciplinary integration including 3D seismic, reservoir simulation and horizontal drilling

    SciTech Connect

    Cooke, D.; Aziz, A.; Baldauff, J.; Diswarin, N.

    1996-12-31

    This case history describes how a multidisciplinary team used a 3D survey and reservoir simulation to review and revise the development plans for the BM platform, located in the B Field, Offshore Northwest Java, Indonesia. The case history starts with the collection of necessary parophysical, geologic and production data. These data are input to a reservoir simulation which shows there should be no problems with the new platform. However, this initial simulation has known problems with contradicting input structure maps and fluid contacts. Hopefully, these problems can be addressed with a new 3D seismic survey - if the seismic data can be acquired, processed, interpreted and input to the simulation before drilling starts at the BM platform. The seismic acquisition could not be done with the traditional towed seismic streamer cables - instead stationary ocean bottom cables with dual geophone-hydrophone sensors were used. Processing of the seismic data was done in a way that allowed interpretation of the critical area even before acquisition of the entire survey was finished. The new 3D structure maps changed the MDT`s opinion of what reservoir and what areas contained the bulk of the oil reserves. Unfortunately, the new maps were not available until after the jacket was set but before the wells drilled. The NMT updated the simulation with the new 3D data, which led to changes in development well bottom hole locations and an ambitious horizontal well.

  10. Application of reservoir management and reservoir simulation to monitor and improve the performance of the M4/7/N1 reservoirs in the Samarang field, offshore Sabah, East Malaysia

    SciTech Connect

    Baxendale, D.

    1995-10-01

    The Samarang field was discovered in 1972, offshore southwest Sabah, East Malaysia. The field was declared commercial in 1974, and first production commenced in 1975. The M4/7/N1 cluster of reservoirs is one of the main groups of reservoirs in the Samarang field, containing some 23% of the field`s expected ultimate recovery. The observed basal/edge natural water drive and the gascap expansion drive are expected to recover about 50% of the M4/7/N1`s original oil in-place. However, the combined drive was not anticipated to fully sweep the reservoir. Hence, the need for a field wide review of the reservoir. To actively manage the remaining hydrocarbon resource a detailed 3D full field simulation project was initiated. A comprehensive geological study of the M4/7/N1 reservoirs was first conducted to formulate the geological input to the simulation model. The model was validated by history matching the reservoir`s seventeen years of production data. This model was then used to actively manage the hydrocarbon resource base by: predicting future oil recovery under various development options, locating potential infill well locations, and by optimizing the reservoir management strategy. Reservoir management of this mature field through the utilization of reservoir simulation tools, has helped to maximize hydrocarbon recovery by determining the optimum depletion strategy with respect to the remaining hydrocarbon resource. Future infill drilling locations have been identified and the results from the model have been used to support the operator`s development strategy for the pool.

  11. Deposition and simulation of sediment transport in the Lower Susquehanna River reservoir system

    USGS Publications Warehouse

    Hainly, R.A.; Reed, L.A.; Flippo, H.N.; Barton, G.J.

    1995-01-01

    The Susquehanna River drains 27,510 square miles in New York, Pennsylvania, and Maryland and is the largest tributary to the Chesapeake Bay. Three large hydroelectric dams are located on the river, Safe Harbor (Lake Clarke) and Holtwood (Lake Aldred) in southern Pennsylvania, and Conowingo (Conowingo Reservoir) in northern Maryland. About 259 million tons of sediment have been deposited in the three reservoirs. Lake Clarke contains about 90.7 million tons of sediment, Lake Aldred contains about 13.6 million tons, and Conowingo Reservoir contains about 155 million tons. An estimated 64.8 million tons of sand, 19.7 million tons of coal, 112 million tons of silt, and 63.3 million tons of clay are deposited in the three reservoirs. Deposition in the reservoirs is variable and ranges from 0 to 30 feet. Chemical analyses of sediment core samples indicate that the three reservoirs combined contain about 814,000 tons of organic nitrogen, 98,900 tons of ammonia as nitrogen, 226,000 tons of phosphorus, 5,610,000 1tons of iron, 2,250,000 tons of aluminum, and about 409,000 tons of manganese. Historical data indicate that Lake Clarke and Lake Aldred have reached equilibrium, and that they no longer store sediment. A comparison of cross-sectional data from Lake Clarke and Lake Aldred with data from Conowingo Reservoir indicates that Conowingo Reservoir will reach equilibrium within the next 20 to 30 years. As the Conowingo Reservoir fills with sediment and approaches equilibrium, the amount of sediment transported to the Chesapeake Bay will increase. The most notable increases will take place when very high flows scour the deposited sediment. Sediment transport through the reservoir system was simulated with the U.S. Army Corps of Engineers' HEC-6 computer model. The model was calibrated with monthly sediment loads for calendar year 1987. Calibration runs with options set for maximum trap efficiency and a "natural" particle-size distribution resulted in an overall computed trap

  12. OGS#PETSc approach for robust and efficient simulations of strongly coupled hydrothermal processes in EGS reservoirs

    NASA Astrophysics Data System (ADS)

    Watanabe, Norihiro; Blucher, Guido; Cacace, Mauro; Kolditz, Olaf

    2016-04-01

    A robust and computationally efficient solution is important for 3D modelling of EGS reservoirs. This is particularly the case when the reservoir model includes hydraulic conduits such as induced or natural fractures, fault zones, and wellbore open-hole sections. The existence of such hydraulic conduits results in heterogeneous flow fields and in a strengthened coupling between fluid flow and heat transport processes via temperature dependent fluid properties (e.g. density and viscosity). A commonly employed partitioned solution (or operator-splitting solution) may not robustly work for such strongly coupled problems its applicability being limited by small time step sizes (e.g. 5-10 days) whereas the processes have to be simulated for 10-100 years. To overcome this limitation, an alternative approach is desired which can guarantee a robust solution of the coupled problem with minor constraints on time step sizes. In this work, we present a Newton-Raphson based monolithic coupling approach implemented in the OpenGeoSys simulator (OGS) combined with the Portable, Extensible Toolkit for Scientific Computation (PETSc) library. The PETSc library is used for both linear and nonlinear solvers as well as MPI-based parallel computations. The suggested method has been tested by application to the 3D reservoir site of Groß Schönebeck, in northern Germany. Results show that the exact Newton-Raphson approach can also be limited to small time step sizes (e.g. one day) due to slight oscillations in the temperature field. The usage of a line search technique and modification of the Jacobian matrix were necessary to achieve robust convergence of the nonlinear solution. For the studied example, the proposed monolithic approach worked even with a very large time step size of 3.5 years.

  13. Simulation of Hydrodynamics and Water Quality in Pueblo Reservoir, Southeastern Colorado, for 1985 through 1987 and 1999 through 2002

    USGS Publications Warehouse

    Galloway, Joel M.; Ortiz, Roderick F.; Bales, Jerad D.; Mau, David P.

    2008-01-01

    Pueblo Reservoir is west of Pueblo, Colorado, and is an important water resource for southeastern Colorado. The reservoir provides irrigation, municipal, and industrial water to various entities throughout the region. In anticipation of increased population growth, the cities of Colorado Springs, Fountain, Security, and Pueblo West have proposed building a pipeline that would be capable of conveying 78 million gallons of raw water per day (240 acre-feet) from Pueblo Reservoir. The U.S. Geological Survey, in cooperation with Colorado Springs Utilities and the Bureau of Reclamation, developed, calibrated, and verified a hydrodynamic and water-quality model of Pueblo Reservoir to describe the hydrologic, chemical, and biological processes in Pueblo Reservoir that can be used to assess environmental effects in the reservoir. Hydrodynamics and water-quality characteristics in Pueblo Reservoir were simulated using a laterally averaged, two-dimensional model that was calibrated using data collected from October 1985 through September 1987. The Pueblo Reservoir model was calibrated based on vertical profiles of water temperature and dissolved-oxygen concentration, and water-quality constituent concentrations collected in the epilimnion and hypolimnion at four sites in the reservoir. The calibrated model was verified with data from October 1999 through September 2002, which included a relatively wet year (water year 2000), an average year (water year 2001), and a dry year (water year 2002). Simulated water temperatures compared well to measured water temperatures in Pueblo Reservoir from October 1985 through September 1987. Spatially, simulated water temperatures compared better to measured water temperatures in the downstream part of the reservoir than in the upstream part of the reservoir. Differences between simulated and measured water temperatures also varied through time. Simulated water temperatures were slightly less than measured water temperatures from March to

  14. Reservoir Simulation on the Cerro Prieto Geothermal Field: A Continuing Study

    SciTech Connect

    Castaneda, M.; Marquez, R.; Arellano, V.; Esquer, C.A.

    1983-12-15

    The Cerro Prieto geothermal field is a liquid-dominated geothermal reservoir of complex geological and hydrological structure. It is located at the southern end of the Salton-Mexicali trough which includes other geothermal anomalies as Heber and East Mesa. Although in 1973, the initial power plant installed capacity was 75 MW of electrical power, this amount increased to 180 MW in 1981 as field development continued. It is expected to have a generating capacity of 620 MW by the end of 1985, when two new plants will be completely in operation. Questions about field deliverability, reservoir life and ultimate recovery related to planned installations are being presently asked. Numerical modeling studies can give very valuable answers to these questions, even at the early stages in the development of a field. An effort to simulate the Cerro Prieto geothermal reservoir has been undergoing for almost two years. A joint project among Comision Federal de Electricidad (CFE), Instituto de Investigaciones Electricas (IIE) and Intercomp of Houstin, Texas, was created to perform reservoir engineering and simulation studies on this field. The final project objective is tosimulate the behavior of the old field region when production from additional wells located in the undeveloped field zones will be used for feeding the new power plants.

  15. Simulating California reservoir operation using the classification and regression-tree algorithm combined with a shuffled cross-validation scheme

    NASA Astrophysics Data System (ADS)

    Yang, Tiantian; Gao, Xiaogang; Sorooshian, Soroosh; Li, Xin

    2016-03-01

    The controlled outflows from a reservoir or dam are highly dependent on the decisions made by the reservoir operators, instead of a natural hydrological process. Difference exists between the natural upstream inflows to reservoirs and the controlled outflows from reservoirs that supply the downstream users. With the decision maker's awareness of changing climate, reservoir management requires adaptable means to incorporate more information into decision making, such as water delivery requirement, environmental constraints, dry/wet conditions, etc. In this paper, a robust reservoir outflow simulation model is presented, which incorporates one of the well-developed data-mining models (Classification and Regression Tree) to predict the complicated human-controlled reservoir outflows and extract the reservoir operation patterns. A shuffled cross-validation approach is further implemented to improve CART's predictive performance. An application study of nine major reservoirs in California is carried out. Results produced by the enhanced CART, original CART, and random forest are compared with observation. The statistical measurements show that the enhanced CART and random forest overperform the CART control run in general, and the enhanced CART algorithm gives a better predictive performance over random forest in simulating the peak flows. The results also show that the proposed model is able to consistently and reasonably predict the expert release decisions. Experiments indicate that the release operation in the Oroville Lake is significantly dominated by SWP allocation amount and reservoirs with low elevation are more sensitive to inflow amount than others.

  16. Validation of the MUFITS reservoir simulator against standard industrial simulation tools for CO2 storage at the Ketzin pilot site

    NASA Astrophysics Data System (ADS)

    Afanasyev, Andrey; Kempka, Thomas; Kühn, Michael; Melnik, Oleg

    2016-04-01

    We give an overview of the reservoir simulator MUFITS capabilities for modelling underground carbon dioxide storage using the EOS-modules GASSTORE and BLACKOIL. The GASSTORE module covers three-phase solid-liquid-gas flows of water, carbon dioxide and salt components. The extended black-oil model is utilized in the BLACKOIL module, which can be applied in the CO2 storage scenarios to two-phase flows of CO2 and brine components. The modules allow comprehensive options including salt precipitation/dissolution, thermal processes, multiple properties regions, and complicated initial vertical equilibration. The PVT tables for the BLACKOIL module can be generated automatically from the GASSTORE module for a given reservoir temperature and brine salinity. We test the simulator against published benchmarking studies. We then consider an application case of CO2 storage at the Ketzin pilot site in Germany. For that purpose, we use a calibrated 3D geological reservoir model comprising a highly heterogeneous distribution of porosity and permeability in a fluvial geological setting. The simulation is conducted using the EOS-module BLACKOIL and the modelling results are in excellent agreement with the results of the industrial simulators applied in previous benchmarks. In particular, the bottom-hole pressure in the injection well, the total mass of dissolved CO2 and spatial CO2 distribution are identical with previously published results.

  17. A methodology for incorporating geomechanically-based fault damage zones models into reservoir simulation

    NASA Astrophysics Data System (ADS)

    Paul, Pijush Kanti

    In the fault damage zone modeling study for a field in the Timor Sea, I present a methodology to incorporate geomechanically-based fault damage zones into reservoir simulation. In the studied field, production history suggests that the mismatch between actual production and model prediction is due to preferential fluid flow through the damage zones associated with the reservoir scale faults, which is not included in the baseline petrophysical model. I analyzed well data to estimate stress heterogeneity and fracture distributions in the reservoir. Image logs show that stress orientations are homogenous at the field scale with a strike-slip/normal faulting stress regime and maximum horizontal stress oriented in NE-SW direction. Observed fracture zones in wells are mostly associated with well scale fault and bed boundaries. These zones do not show any anomalies in production logs or well test data, because most of the fractures are not optimally oriented to the present day stress state, and matrix permeability is high enough to mask any small anomalies from the fracture zones. However, I found that fracture density increases towards the reservoir scale faults, indicating high fracture density zones or damage zones close to these faults, which is consistent with the preferred flow direction indicated by interference and tracer test done between the wells. It is well known from geologic studies that there is a concentration of secondary fractures and faults in a damage zone adjacent to larger faults. Because there is usually inadequate data to incorporate damage zone fractures and faults into reservoir simulation models, in this study I utilized the principles of dynamic rupture propagation from earthquake seismology to predict the nature of fractured/damage zones associated with reservoir scale faults. The implemented workflow can be used to more routinely incorporate damage zones into reservoir simulation models. Applying this methodology to a real reservoir utilizing

  18. Numerical Simulation of Injectivity Effects of Mineral Scaling and Clay Swelling in a Fractured Geothermal Reservoir

    SciTech Connect

    Xu, Tianfu; Pruess, Karsten

    2004-05-10

    A major concern in the development of hot dry rock (HDR) and hot fractured rock (HFR) reservoirs is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths such as those caused by thermally-induced stress cracking. Past analyses of HDR and HFR reservoirs have tended to focus primarily on the coupling between hydrology (flow), heat transfer, and rock mechanics. Recent studies suggest that rock-fluid interactions and associated mineral dissolution and precipitation effects could have a major impact on the long-term performance of HFR reservoirs. The present paper uses recent European studies as a starting point to explore chemically-induced effects of fluid circulation in HFR systems. We examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance by maintaining or even enhancing injectivity. Chemical manipulations considered here include pH modification and dilution with fresh water. We performed coupled thermo-hydrologic-chemical simulations in which the fractured medium was represented by a one-dimensional MINC model (multiple interacting continua), using the non-isothermal multi-phase reactive geochemical transport code TOUGHREACT. Results indicate that modifying the injection water chemistry can enhance mineral dissolution and reduce clay swelling. Chemical interactions between rocks and fluids will change a HFR reservoir over time, with some changes favorable and others not. A detailed, quantitative understanding of processes and mechanisms can suggest chemical methods for reservoir management, which may be employed to improve the performance of the geothermal system.

  19. Analysis of numerical simulations and influencing factors of seasonal manganese pollution in reservoirs.

    PubMed

    Peng, Hui; Zheng, Xilai; Chen, Lei; Wei, Yang

    2016-07-01

    Seasonal manganese pollution has become an increasingly pressing water quality issue for water supply reservoirs in recent years. Manganese is a redox-sensitive element and is released from sediment under anoxic conditions near the sediment-water interface during summer and autumn, when water temperature stratification occurs. The reservoir water temperature and water dynamic conditions directly influence the formation of manganese pollution. Numerical models are useful tools to quantitatively evaluate manganese pollution and its influencing factors. This paper presents a reservoir manganese pollution model by adding a manganese biogeochemical module to a water quality model-CE-QUAL-W2. The model is applied to the Wangjuan reservoir (Qingdao, China), which experiences manganese pollution during summer and autumn. Field data are used to verify the model, and the results show that the model can reproduce the main features of the thermal stratification and manganese distribution. The model is used to evaluate the manganese pollution process and its four influencing factors, including air temperature, water level, wind speed, and wind directions, through different simulation scenarios. The results show that all four factors can influence manganese pollution. High air temperature, high water level, and low wind speed aggravate manganese pollution, while low air temperature, low water level, and high wind speed reduce manganese pollution. Wind that travels in the opposite direction of the flow aggravates manganese pollution, while wind in the same direction as the flow reduces manganese pollution. This study provides useful information to improve our understanding of seasonal manganese pollution in reservoirs, which is important for reservoir manganese pollution warnings and control.

  20. Simulating California Reservoir Operation Using the Classification and Regression Tree Algorithm Combined with a Shuffled Cross-Validation Scheme

    NASA Astrophysics Data System (ADS)

    Yang, T.; Gao, X.; Sorooshian, S.; Li, X.

    2015-12-01

    The controlled outflows from a reservoir or dam are highly dependent on the decisions made by the reservoir operators, instead of a natural hydrological process. Difference exists between the natural upstream inflows to reservoirs, and the controlled outflows from reservoirs that supply the downstream users. With the decision maker's awareness of changing climate, reservoir management requires adaptable means to incorporate more information into decision making, such as the consideration of policy and regulation, environmental constraints, dry/wet conditions, etc. In this paper, a reservoir outflow simulation model is presented, which incorporates one of the well-developed data-mining models (Classification and Regression Tree) to predict the complicated human-controlled reservoir outflows and extract the reservoir operation patterns. A shuffled cross-validation approach is further implemented to improve model's predictive performance. An application study of 9 major reservoirs in California is carried out and the simulated results from different decision tree approaches are compared with observation, including original CART and Random Forest. The statistical measurements show that CART combined with the shuffled cross-validation scheme gives a better predictive performance over the other two methods, especially in simulating the peak flows. The results for simulated controlled outflow, storage changes and storage trajectories also show that the proposed model is able to consistently and reasonably predict the human's reservoir operation decisions. In addition, we found that the operation in the Trinity Lake, Oroville Lake and Shasta Lake are greatly influenced by policy and regulation, while low elevation reservoirs are more sensitive to inflow amount than others.

  1. Reservoir Control Center: Activities and Accomplishments of the Southwestern Division of the Army Corps of Engineers Related to Reservoir Regulation and Water Management. Part 1.

    DTIC Science & Technology

    1981-01-01

    within the division, including multiple level outlet facilities, reservoir simulation studies, reregulation structures, and release reoxy- genation...through a careful evaluation of their problems a study was designed including data collection, mathematical reservoir simulation models, and a physical...model. In the reservoir simulation , the Eiker model and a modified version of the WESTEX model which included a suspended particle settling routine were

  2. An improved multilevel Monte Carlo method for estimating probability distribution functions in stochastic oil reservoir simulations

    DOE PAGES

    Lu, Dan; Zhang, Guannan; Webster, Clayton G.; ...

    2016-12-30

    In this paper, we develop an improved multilevel Monte Carlo (MLMC) method for estimating cumulative distribution functions (CDFs) of a quantity of interest, coming from numerical approximation of large-scale stochastic subsurface simulations. Compared with Monte Carlo (MC) methods, that require a significantly large number of high-fidelity model executions to achieve a prescribed accuracy when computing statistical expectations, MLMC methods were originally proposed to significantly reduce the computational cost with the use of multifidelity approximations. The improved performance of the MLMC methods depends strongly on the decay of the variance of the integrand as the level increases. However, the main challengemore » in estimating CDFs is that the integrand is a discontinuous indicator function whose variance decays slowly. To address this difficult task, we approximate the integrand using a smoothing function that accelerates the decay of the variance. In addition, we design a novel a posteriori optimization strategy to calibrate the smoothing function, so as to balance the computational gain and the approximation error. The combined proposed techniques are integrated into a very general and practical algorithm that can be applied to a wide range of subsurface problems for high-dimensional uncertainty quantification, such as a fine-grid oil reservoir model considered in this effort. The numerical results reveal that with the use of the calibrated smoothing function, the improved MLMC technique significantly reduces the computational complexity compared to the standard MC approach. Finally, we discuss several factors that affect the performance of the MLMC method and provide guidance for effective and efficient usage in practice.« less

  3. An improved multilevel Monte Carlo method for estimating probability distribution functions in stochastic oil reservoir simulations

    SciTech Connect

    Lu, Dan; Zhang, Guannan; Webster, Clayton G.; Barbier, Charlotte N.

    2016-12-30

    In this paper, we develop an improved multilevel Monte Carlo (MLMC) method for estimating cumulative distribution functions (CDFs) of a quantity of interest, coming from numerical approximation of large-scale stochastic subsurface simulations. Compared with Monte Carlo (MC) methods, that require a significantly large number of high-fidelity model executions to achieve a prescribed accuracy when computing statistical expectations, MLMC methods were originally proposed to significantly reduce the computational cost with the use of multifidelity approximations. The improved performance of the MLMC methods depends strongly on the decay of the variance of the integrand as the level increases. However, the main challenge in estimating CDFs is that the integrand is a discontinuous indicator function whose variance decays slowly. To address this difficult task, we approximate the integrand using a smoothing function that accelerates the decay of the variance. In addition, we design a novel a posteriori optimization strategy to calibrate the smoothing function, so as to balance the computational gain and the approximation error. The combined proposed techniques are integrated into a very general and practical algorithm that can be applied to a wide range of subsurface problems for high-dimensional uncertainty quantification, such as a fine-grid oil reservoir model considered in this effort. The numerical results reveal that with the use of the calibrated smoothing function, the improved MLMC technique significantly reduces the computational complexity compared to the standard MC approach. Finally, we discuss several factors that affect the performance of the MLMC method and provide guidance for effective and efficient usage in practice.

  4. Computer simulation of reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout

    USGS Publications Warehouse

    Hsieh, Paul

    2010-01-01

    This report describes the application of a computer model to simulate reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout. Reservoir and fluid data used for model development are based on (1) information released in BP's investigation report of the incident, (2) information provided by BP personnel during meetings in Houston, Texas, and (3) calibration by history matching to shut-in pressures measured in the capping stack during the Well Integrity Test. The model is able to closely match the measured shut-in pressures. In the simulation of the 86-day period from the blowout to shut in, the simulated reservoir pressure at the well face declines from the initial reservoir pressure of 11,850 pounds per square inch (psi) to 9,400 psi. After shut in, the simulated reservoir pressure recovers to a final value of 10,300 psi. The pressure does not recover back to the initial pressure owing to reservoir depletion caused by 86 days of oil discharge. The simulated oil flow rate declines from 63,600 stock tank barrels per day just after the Deepwater Horizon blowout to 52,600 stock tank barrels per day just prior to shut in. The simulated total volume of oil discharged is 4.92 million stock tank barrels. The overall uncertainty in the simulated flow rates and total volume of oil discharged is estimated to be + or - 10 percent.

  5. Simulation studies to evaluate the effect of fracture closure on the performance of naturally fractured reservoirs. Annual report

    SciTech Connect

    Not Available

    1991-10-01

    The first of a three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The objectives of the study are to (1) evaluate the reservoir conditions where fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. Simulation studies were conducted with a dual porosity simulator capable of simulating the performance of vertical and horizontal wells. Each simulator was initialized using properties typical of the Austin Chalk reservoir in Pearsall Field, Texas. Simulations of both vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure change. Sensitivity runs indicate that the simulator is predicting the effects of critical reservoir parameters in a logical and consistent manner. The results to-date confirm that horizontal wells can increase both oil recovery rate and total oil recovery from naturally fractured reservoirs. The year one simulation results will provide the baseline for the ongoing study which will evaluate the performance degradation caused by the sensitivity of fracture permeability to pressure change, and investigate fluid injection pressure maintenance as a means to improve oil recovery performance. The study is likely to conclude that fracture closure decreases oil recovery and that pressure support achieved through fluid injection could be beneficial in improving recovery.

  6. Simulation of extreme reservoir level distribution with the SCHADEX method (EXTRAFLO project)

    NASA Astrophysics Data System (ADS)

    Paquet, Emmanuel; Penot, David; Garavaglia, Federico

    2013-04-01

    The standard practice for the design of dam spillways structures and gates is to consider the maximum reservoir level reached for a given hydrologic scenario. This scenario has several components: peak discharge, flood volumes on different durations, discharge gradients etc. Within a probabilistic analysis framework, several scenarios can be associated with different return times, although a reference return level (e.g. 1000 years) is often prescribed by the local regulation rules or usual practice. Using continuous simulation method for extreme flood estimation is a convenient solution to provide a great variety of hydrological scenarios to feed a hydraulic model of dam operation: flood hydrographs are explicitly simulated by a rainfall-runoff model fed by a stochastic rainfall generator. The maximum reservoir level reached will be conditioned by the scale and the dynamics of the generated hydrograph, by the filling of the reservoir prior to the flood, and by the dam gates and spillway operation during the event. The simulation of a great number of floods will allow building a probabilistic distribution of maximum reservoir levels. A design value can be chosen at a definite return level. An alternative approach is proposed here, based on the SCHADEX method for extreme flood estimation, proposed by Paquet et al. (2006, 2013). SCHADEX is a so-called "semi-continuous" stochastic simulation method in that flood events are simulated on an event basis and are superimposed on a continuous simulation of the catchment saturation hazard using rainfall-runoff modelling. The SCHADEX process works at the study time-step (e.g. daily), and the peak flow distribution is deduced from the simulated daily flow distribution by a peak-to-volume ratio. A reference hydrograph relevant for extreme floods is proposed. In the standard version of the method, both the peak-to-volume and the reference hydrograph are constant. An enhancement of this method is presented, with variable peak

  7. Geological and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir

    SciTech Connect

    Chidsey Jr., Thomas C.

    2001-10-31

    The objective of the Ferron Sandstone project was to develop a comprehensive, interdisciplinary, quantitative characterization f fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah was collected. Both new and existing data was integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations.

  8. SAG injection in a North Sea stratified reservoir: Flow experiment and simulation

    SciTech Connect

    Hanssen, J.E.; Surguchev, L.M.; Svorstoel, I.

    1994-12-31

    This paper is a study of a novel recovery process for stratified reservoirs with large permeability contrasts. A slug of foaming surfactant is injected alternately with gas, thus by analogy with WAG making this a SAG injection process. A combined experimental and numerical evaluation demonstrating effective diversion by foam and significant recovery potential over WAG of the method is reported. An experiment with the new process was performed in a visual 2-D porous medium flow model approximately scaled to the conditions of a North Sea reservoir that is characterized by high permeability contrast and limited interlayer communication. The experiment showed poor performance of conventional WAG, which swept mainly the high-permeable layer. Placement of a surfactant slug and later foam generation in the swept layer was successfully demonstrated and gave efficient injectant diversion into the other layers, resulting in complete sweep of the reservoir model by continued WAG. In summary the results of this paper show experimentally and by simulation on the same system that SAG injection as implemented here is superior to WAG injection and that the rich observations made in the experimental ca be matched with reasonable accuracy using a commercial simulator with only empirical parameters.

  9. Simplifying the task of grouping fluid components in compositional reservoir simulation

    SciTech Connect

    Lomeland, F.; Harstad, O.

    1995-04-01

    The main results from a compositional reservoir simulation are the production rates. Normally, these are stable oil and dry gas streams, but other streams may also be reported. The detailed description of the fluid compositions can therefore be reduced to some extent if the overall description of the fluid properties is acceptable. This is achieved by lumping the components into component groups called pseudocomponents. This reduces the computation time and the needed memory. The traditional way to prepare a fluid model with pseudocomponents is to group them based on personal experience and parameter regression. This requires a lot of experience and continues practice, and probably represents one of the greatest obstacles for a reservoir engineer confronted with compositional reservoir simulation for the first time. This paper presents an automatic method of selecting pseudocomponents. The authors will compare the new method with other existing methods that automatically group components into pseudocomponents. The existing methods used in the comparison follow: (1) the method of mole-weighted average with components grouped to have approximately equal mole fraction; (2) the method of mass-weighted average with components grouped to have approximately equal mass fraction; (3) the method of Newly et al.

  10. Simulated effects of proposed reservoir-development alternatives on streamflow quantity in the White River, Colorado and Utah

    USGS Publications Warehouse

    Kuhn, Gerhard; Ellis, S.R.

    1984-01-01

    Numerous reservoirs have been proposed for the White River basin in Colorado and Utah, primarily to provide water for oil-shale development. A multireservoir-flow model was used to simulate the effects of streamflow withdrawal at four of the proposed reservoirs using historical streamflow data from the 1932-81 water years. The proposed reservoirs considered in the study were Avery, Powell Park, Taylor Draw, and White River Reservoirs; construction of Taylor Draw Dam was completed during the study. Annual streamflow depletions from the White River ranging from about 93,000 to 226,000 acre-feet were simulated for the 50 year period. Simulated streamflow throughout the year generally became smaller and more constant as streamflow throughout the year generally became smaller and more constant as streamflow depletion increased. Minimum streamflow requirements would not have been met for a maximum of 13 years and water-use requirements associated with the proposed reservoirs would not have been met for a maximum of 3 years. The current water-use pattern, which depletes about 40,000 acre-feet per year and is dominated by irrigation of hay meadows and pastureland, was maintained in the simulation. Relations between reservoir active capacity and yield applicable to the White River also were developed. These relations show that reservoir storage of about 400,000 acre-feet is the maximum practicable for the White River. (USGS)

  11. Characterization and simulation of an exhumed fractured petroleum reservoir. Final report, March 18, 1996--September 30, 1998

    SciTech Connect

    Forster, C.B.; Nielson, D.L.; Deo, M.

    1998-12-01

    An exhumed fractured reservoir located near Alligator Ridge in central Nevada provides the basis for developing and testing different approaches for simulating fractured petroleum reservoirs. The fractured analog reservoir comprises a 90 m thickness of silty limestone and shaly interbeds within the Devonian Pilot Shale. A period of regional compression followed by ongoing basin and range extension has created faults and fractures that, in tern, have controlled the migration of both oil and gold ore-forming fluids. Open pit gold mines provide access for observing oil seepage, collecting the detailed fracture data needed to map variations in fracture intensity near faults, build discrete fracture network models and create equivalent permeability structures. Fault trace patterns mapped at the ground surface provide a foundation for creating synthetic fault trace maps using a stochastic procedure conditioned by the outcrop data. Conventional simulations of petroleum production from a 900 by 900 m sub-domain within the reservoir analog illustrate the possible influence of faults and fractures on production. The consequences of incorporating the impact of different stress states (e.g., extension, compression or lithostatic) are also explored. Simulating multiphase fluid flow using a discrete fracture, finite element simulator illustrates how faults acting as conduits might be poorly represented by the upscaling procedures used to assign equivalent permeability values within reservoir models. The parallelized reservoir simulators developed during this project provide a vehicle to evaluate when it might be necessary to incorporate very fine scale grid networks in conventional reservoir simulators or to use finely gridded discrete fracture reservoir simulators.

  12. Some Current Problems in Simulator Design, Testing and Use.

    ERIC Educational Resources Information Center

    Caro, Paul W.

    Concerned with the general problem of the effectiveness of simulator training, this report reflects information developed during the conduct of aircraft simulator training research projects sponsored by the Air Force, Army, Navy, and Coast Guard. Problems are identified related to simulator design, testing, and use, all of which impact upon…

  13. Feasibility of steam injection process in a thin, low-permeability heavy oil reservoir of Arkansas -- a numerical simulation study

    SciTech Connect

    Sarkar, A.K.; Sarathi, P.S.

    1993-12-01

    This report details the findings of an in-depth study undertaken to assess the viability of the steam injection process in the heavy oil bearing Nacatoch sands of Arkansas. Published screening criteria and DOE`s steamflood predictive models were utilized to screen and select reservoirs for further scrutiny. Although, several prospects satisfied the steam injection screening criteria, only a single candidate was selected for detailed simulation studies. The selection was based on the availability of needed data for simulation and the uniqueness of the reservoir. The reservoir investigated is a shallow, thin, low-permeability reservoir with low initial oil saturation and has an underlying water sand. The study showed that the reservoir will respond favorably to steamdrive, but not to cyclic steaming. Steam stimulation, however, is necessary to improve steam injectivity during subsequent steamdrive. Further, in such marginal heavy oil reservoirs (i.e., reservoir characterized by thin pay zone and low initial oil saturation) conventional steamdrive (i.e., steam injection using vertical wells) is unlikely to be economical, and nonconventional methods must be utilized. It was found that the use of horizontal injectors and horizontal producers significantly improved the recovery and oil-steam ratio and improved the economics. It is recommended that the applicability of horizontal steam injection technology in this reservoir be further investigated.

  14. Analysis of induced seismicity and heat transfer in geothermal reservoirs by coupled simulation

    NASA Astrophysics Data System (ADS)

    Gan, Quan

    . Conversely, at high relative non-dimensional flow rates the propagating pressure pulse is larger and migrates more quickly through the reservoir but the thermal drawdown is uniform across the reservoir and without the presence of a distinct thermal front, and less capable of triggering late-stage seismicity. In Chapter 2 we develop a dimensionless model to predict the thermal drawdown response, and quantify the relationship between the timing and magnitude of late stage seismic event and the induced thermal stress from thermal drawdown. We evaluate the uniformity of thermal drawdown as a function of a dimensionless flow rate QD that scales with fracture spacing s( m), injection rate q (kg/s), and the distance between the injector and the target point L* ( Qd ∝ qs2 / L*). By assuming the dominant heat transfer by heat conduction within the fractured medium, this model is either capable to predict the timing of induced seismicity by the thermal stress by the analytical formula. Due to the significant influence of fracture network geometry in heat transfer and induced seismicity, a discrete fracture network model is developed (Chapter 3) to couple stress and fluid flow in a discontinuous fractured mass represented as a continuum by coupling the continuum simulator TF_FLAC 3D with cell-by-cell discontinuum laws for deformation and flow. Both equivalent medium crack and permeability tensor approaches are employed to characterize preexisting discrete fractures. The evolution of fracture permeability accommodates stress-dependent aperture under different stress states, including normal closure, shear dilation, and for fracture walls out of contact under tensile loading. This discrete fracture network model is applied (Chapter 4) in a generic reservoir with an initial permeability in the range of 10-17 to 10-16 m2, fracture density of ~0.09m -1 and fractures oriented such that either none, one, or both sets of fractures are critically stressed. For a given reservoir with a pre

  15. Numerical simulations of CO2 -assisted gas production from hydrate reservoirs

    NASA Astrophysics Data System (ADS)

    Sridhara, P.; Anderson, B. J.; Myshakin, E. M.

    2015-12-01

    A series of experimental studies over the last decade have reviewed the feasibility of using CO2 or CO2+N2 gas mixtures to recover CH4 gas from hydrates deposits. That technique would serve the dual purpose of CO2 sequestration and production of CH4 while maintaining the geo-mechanical stability of the reservoir. In order to analyze CH4 production process by means of CO2 or CO2+N2 injection into gas hydrate reservoirs, a new simulation tool, Mix3HydrateResSim (Mix3HRS)[1], was previously developed to account for the complex thermodynamics of multi-component hydrate phase and to predict the process of CH4 substitution by CO2 (and N2) in the hydrate lattice. In this work, Mix3HRS is used to simulate the CO2 injection into a Class 2 hydrate accumulation characterized by a mobile aqueous phase underneath a hydrate bearing sediment. That type of hydrate reservoir is broadly confirmed in permafrost and along seashore. The production technique implies a two-stage approach using a two-well design, one for an injector and one for a producer. First, the CO2 is injected into the mobile aqueous phase to convert it into immobile CO2 hydrate and to initiate CH4 release from gas hydrate across the hydrate-water boundary (generally designating the onset of a hydrate stability zone). Second, CH4 hydrate decomposition is induced by the depressurization method at a producer to estimate gas production potential over 30 years. The conversion of the free water phase into the CO2 hydrate significantly reduces competitive water production in the second stage, thereby improving the methane gas production. A base case using only the depressurization stage is conducted to compare with enhanced gas production predicted by the CO2-assisted technique. The approach also offers a possibility to permanently store carbon dioxide in the underground formation to greater extent comparing to a direct injection of CO2 into gas hydrate sediment. Numerical models are based on the hydrate formations at the

  16. The big fat LARS - a LArge Reservoir Simulator for hydrate formation and gas production

    NASA Astrophysics Data System (ADS)

    Beeskow-Strauch, Bettina; Spangenberg, Erik; Schicks, Judith M.; Giese, Ronny; Luzi-Helbing, Manja; Priegnitz, Mike; Klump, Jens; Thaler, Jan; Abendroth, Sven

    2013-04-01

    Simulating natural scenarios on lab scale is a common technique to gain insight into geological processes with moderate effort and expenses. Due to the remote occurrence of gas hydrates, their behavior in sedimentary deposits is largely investigated on experimental set ups in the laboratory. In the framework of the submarine gas hydrate research project (SUGAR) a large reservoir simulator (LARS) with an internal volume of 425 liter has been designed, built and tested. To our knowledge this is presently a word-wide unique set up. Because of its large volume it is suitable for pilot plant scale tests on hydrate behavior in sediments. That includes not only the option of systematic tests on gas hydrate formation in various sedimentary settings but also the possibility to mimic scenarios for the hydrate decomposition and subsequent natural gas extraction. Based on these experimental results various numerical simulations can be realized. Here, we present the design and the experimental set up of LARS. The prerequisites for the simulation of a natural gas hydrate reservoir are porous sediments, methane, water, low temperature and high pressure. The reservoir is supplied by methane-saturated and pre-cooled water. For its preparation an external gas-water mixing stage is available. The methane-loaded water is continuously flushed into LARS as finely dispersed fluid via bottom-and-top-located sparger. The LARS is equipped with a mantle cooling system and can be kept at a chosen set temperature. The temperature distribution is monitored at 14 reasonable locations throughout the reservoir by Pt100 sensors. Pressure needs are realized using syringe pump stands. A tomographic system, consisting of a 375-electrode-configuration is attached to the mantle for the monitoring of hydrate distribution throughout the entire reservoir volume. Two sets of tubular polydimethylsiloxan-membranes are applied to determine gas-water ratio within the reservoir using the effect of permeability

  17. Revised Comparisons of Simulated Hydrodynamics and Water Quality for Projected Demands in 2046, Pueblo Reservoir, Southeastern Colorado

    USGS Publications Warehouse

    Ortiz, Roderick F.; Miller, Lisa D.

    2009-01-01

    Pueblo Reservoir is one of southeastern Colorado's most valuable water resources. The reservoir provides irrigation, municipal, and industrial water to various entities throughout the region. The reservoir also provides flood control, recreational activities, sport fishing, and wildlife enhancement to the region. The Southern Delivery System (SDS) project is a regional water-delivery project that has been proposed to provide a safe, reliable, and sustainable water supply through the foreseeable future (2046) for Colorado Springs, Fountain, Security, and Pueblo West. Discussions with the Bureau of Reclamation and the U.S. Geological Survey led to a cooperative agreement to simulate the hydrodynamics and water quality of Pueblo Reservoir. This work has been completed and described in a previously published report, U.S. Geological Survey Scientific Investigations Report 2008-5056. Additionally, there was a need to make comparisons of simulated hydrodynamics and water quality for projected demands associated with the various Environmental Impact Statements (EIS) alternatives and plans by Pueblo West to discharge treated wastewater into the reservoir. Wastewater plans by Pueblo West are fully independent of the SDS project. This report compares simulated hydrodynamics and water quality for projected demands in Pueblo Reservoir resulting from changes in inflow and water quality entering the reservoir, and from changes to withdrawals from the reservoir as projected for the year 2046. Four of the seven EIS alternatives were selected for scenario simulations. The four U.S. Geological Survey simulation scenarios were the No Action scenario (EIS Alternative 1), the Downstream Diversion scenario (EIS Alternative 2), the Upstream Return-Flow scenario (EIS Alternative 4), and the Upstream Diversion scenario (EIS Alternative 7). Additionally, the results of an Existing Conditions scenario (year 2006 demand conditions) were compared to the No Action scenario (projected demands in

  18. Prediction of effects of hydraulic fracturing using reservoir and well flow simulation

    SciTech Connect

    Mineyuki Hanano; Tayuki Kondo

    1992-01-01

    This paper presents a method to predict and evaluate effects of hydraulic fracturing jobs by using reservoir and well flow numerical simulation. The concept of the method i5 that steam production rate at the operating well head pressure is predicted with different fracture conditions which would be attained by the hydraulic fracturing jobs. Then, the effects of the hydraulic fracturing is evaluated by comparing the predicted steam production rate and that before the hydraulic fracturing. This course of analysis will suggest how large fracture should be created by the fracturing job to attain large enough increase in steam production at the operating condition and the best scheme of the hydraulic fracturing job.

  19. Block-preconditioned conjugate-gradient-like methods for numerical reservoir simulation

    SciTech Connect

    Eisenstat, S.C.; Elman, H.C.; Schultz, M.H.

    1985-02-01

    The authors describe a collection of block-preconditioners for use in solving large sparse linear systems of equations by iterative methods, and they compare their performance with several point-preconditioners in solving some systems arising in numerical reservoir simulation. They consider block-preconditioners that handle either lines or planes in an implicit manner, and pointwise incomplete LU factorizations combined with partial elimination preprocessors. Their conclusions are that the best of the pointwise methods are both more robust and faster, but that the best of the block methods are competitive for certain orderings of unknowns and require less storage.

  20. Parallel, Multigrid Finite Element Simulator for Fractured/Faulted and Other Complex Reservoirs based on Common Component Architecture (CCA)

    SciTech Connect

    Milind Deo; Chung-Kan Huang; Huabing Wang

    2008-08-31

    Black-oil, compositional and thermal simulators have been developed to address different physical processes in reservoir simulation. A number of different types of discretization methods have also been proposed to address issues related to representing the complex reservoir geometry. These methods are more significant for fractured reservoirs where the geometry can be particularly challenging. In this project, a general modular framework for reservoir simulation was developed, wherein the physical models were efficiently decoupled from the discretization methods. This made it possible to couple any discretization method with different physical models. Oil characterization methods are becoming increasingly sophisticated, and it is possible to construct geologically constrained models of faulted/fractured reservoirs. Discrete Fracture Network (DFN) simulation provides the option of performing multiphase calculations on spatially explicit, geologically feasible fracture sets. Multiphase DFN simulations of and sensitivity studies on a wide variety of fracture networks created using fracture creation/simulation programs was undertaken in the first part of this project. This involved creating interfaces to seamlessly convert the fracture characterization information into simulator input, grid the complex geometry, perform the simulations, and analyze and visualize results. Benchmarking and comparison with conventional simulators was also a component of this work. After demonstration of the fact that multiphase simulations can be carried out on complex fracture networks, quantitative effects of the heterogeneity of fracture properties were evaluated. Reservoirs are populated with fractures of several different scales and properties. A multiscale fracture modeling study was undertaken and the effects of heterogeneity and storage on water displacement dynamics in fractured basements were investigated. In gravity-dominated systems, more oil could be recovered at a given pore

  1. Multi-objective combined simulation-optimization of Lake Tana multi reservoir system, Ethiopia, using two different generalized reservoir system operation models

    NASA Astrophysics Data System (ADS)

    Müller, R.; Saliha, A. H.; Schütze, N.

    2012-04-01

    Finding optimal management strategies can be a challenging task when water resources systems serve multiple contrary goals. Reasonable trade offs among these goals has to be found. Multi-objective optimization (MOO) is able to obtain a so called Pareto front containing multiple trade off solutions (Pareto optimal solutions). An attractive and powerful MOO method is multi-objective combined simulation-optimization (MOCSO). Generally MOCSO model consists of mainly two components, a simulation model and a multi-objective optimization algorithm. Generalized reservoir system operation models (GRSOM) are commonly used as simulation models in water resources planning and management of multi-reservoir systems. The purpose of the GRSOM in MOCSO is to simulate a specific management in order to evaluate the objective functions for the multi-objective optimization algorithm. As the distribution of water in reservoir system is affected by the particular operation of the GRSOM model, the choice of the simulation model is a crucial step in MOCSO setup which may significantly affect the obtained results. In a case study of Lake Tana sub basin (Ethiopia) two MOCSO models are compared. The general reservoir operation simulation models HEC-5 and OASIS (Operational Analysis and Simulation of Integrated Systems) are combined with the Multi-Objective Covariance Matrix-Adaptation Evolution Strategy (MO-CMA-ES). HEC-5 is a pure simulation model which computes the distribution of water in the system sequentially and serially from upstream to downstream following an given algorithm. OASIS, a simulation-optimization model, incorporates a linear or nonlinear solver which distributes the water sequentially in the system according to objective function defined by the decision maker. Lake Tana is the largest fresh water lake in Ethiopia. Its water resources are controllable due to the Chara Chara weir. For hydropower production water is directly diverted from Lake Tana to Belles sub

  2. Three-dimensional geomechanical simulation of reservoir compaction and implications for well failures in the Belridge diatomite

    SciTech Connect

    Fredrich, J.T.; Argueello, J.G.; Thorne, B.J.; Wawersik, W.R. |

    1996-11-01

    This paper describes an integrated geomechanics analysis of well casing damage induced by compaction of the diatomite reservoir at the Belridge Field, California. Historical data from the five field operators were compiled and analyzed to determine correlations between production, injection, subsidence, and well failures. The results of this analysis were used to develop a three-dimensional geomechanical model of South Belridge, Section 33 to examine the diatomite reservoir and overburden response to production and injection at the interwell scale and to evaluate potential well failure mechanisms. The time-dependent reservoir pressure field was derived from a three-dimensional finite difference reservoir simulation and used as input to three-dimensional non-linear finite element geomechanical simulations. The reservoir simulation included -200 wells and covered 18 years of production and injection. The geomechanical simulation contained 437,100 nodes and 374,130 elements with the overburden and reservoir discretized into 13 layers with independent material properties. The results reveal the evolution of the subsurface stress and displacement fields with production and injection and suggest strategies for reducing the occurrence of well casing damage.

  3. Numerical Simulation of Subsurface Transport and Groundwater Impacts from Hydraulic Fracturing of Tight/Shale Gas Reservoirs

    NASA Astrophysics Data System (ADS)

    Reagan, M. T.; Moridis, G. J.; Keen, N. D.

    2014-12-01

    The use of reservoir stimulation techniques, such as hydraulic fracturing, has grown tremendously over the last decade, and concerns have arisen that reservoir stimulation creates environmental threats through the creation of permeable pathways that could connect the stimulated reservoir to shallower groundwater aquifers. This study investigates, by numerical simulation, gas and water transport between a deeper tight-gas reservoir and a shallower overlying groundwater aquifer following hydraulic fracturing operations, assuming that the formation of a connecting pathway has already occurred. We focus on two general transport scenarios: 1) communication between the reservoir and aquifer via a connecting fracture or fault and 2) communication via a deteriorated, preexisting nearby well. The simulations explore a range of permeabilities and geometries over time scales, and evaluate the mechanisms and factors that could lead to the escape of gas or reservoir fluid and the contamination of groundwater resources. We also examine the effects of overpressured reservoirs, and explore long-term transport processes as part of a continuing study. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Gas production from the reservoir via a horizontal well is likely to mitigate release through the reduction of available free gas and the lowering of reservoir pressure. We also find that fractured tight-gas reservoirs are unlikely to act as a continuing source of large volumes of migrating gas, and incidents of gas escape are likely to be limited in duration and scope. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.

  4. Simulation studies to evaluate the effect of fracture closure on the performance of naturally fractured reservoirs. Annual report

    SciTech Connect

    Not Available

    1992-11-01

    The second year of this three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The overall objectives of the study are to: (1) evaluate the reservoir conditions where fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. Simulation studies have been conducted with a dual porosity simulator capable of simulating the performance of vertical and horizontal wells. Each simulation model has been initialized with properties typical of the Austin Chalk reservoir in Pearsall Field, Texas. During year one, simulations of both vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure charge. The results confirmed that horizontal wells could increase both rate of oil recovery and total oil recovery from naturally fractured reservoirs. During the second year the performances of the same vertical and horizontal wells were evaluated with the assumption that fracture permeability was a function of reservoir pressure. This required repetition of most of the natural depletion cases simulated in year one while invoking the pressure-sensitive fracture permeability option. To investigate sensitivity to in situ stress, two stress conditions were simulated for each primary variable. The water injection cases, begun in year one, were extended to include most of the reservoir parameters investigated for natural depletion, including fracture permeability as a function of net stress and the use of horizontal wells. The results thus far confirm that pressure-sensitive fractures degrade well performance and that the degradation is reduced by water injection pressure maintenance. Furthermore, oil recovery can be significantly increased by water injection pressure maintenance.

  5. Numerical simulation of groundwater movement and managed aquifer recharge from Sand Hollow Reservoir, Hurricane Bench area, Washington County, Utah

    USGS Publications Warehouse

    Marston, Thomas M.; Heilweil, Victor M.

    2012-01-01

    The Hurricane Bench area of Washington County, Utah, is a 70 square-mile area extending south from the Virgin River and encompassing Sand Hollow basin. Sand Hollow Reservoir, located on Hurricane Bench, was completed in March 2002 and is operated primarily as a managed aquifer recharge project by the Washington County Water Conservancy District. The reservoir is situated on a thick sequence of the Navajo Sandstone and Kayenta Formation. Total recharge to the underlying Navajo aquifer from the reservoir was about 86,000 acre-feet from 2002 to 2009. Natural recharge as infiltration of precipitation was approximately 2,100 acre-feet per year for the same period. Discharge occurs as seepage to the Virgin River, municipal and irrigation well withdrawals, and seepage to drains at the base of reservoir dams. Within the Hurricane Bench area, unconfined groundwater-flow conditions generally exist throughout the Navajo Sandstone. Navajo Sandstone hydraulic-conductivity values from regional aquifer testing range from 0.8 to 32 feet per day. The large variability in hydraulic conductivity is attributed to bedrock fractures that trend north-northeast across the study area.A numerical groundwater-flow model was developed to simulate groundwater movement in the Hurricane Bench area and to simulate the movement of managed aquifer recharge from Sand Hollow Reservoir through the groundwater system. The model was calibrated to combined steady- and transient-state conditions. The steady-state portion of the simulation was developed and calibrated by using hydrologic data that represented average conditions for 1975. The transient-state portion of the simulation was developed and calibrated by using hydrologic data collected from 1976 to 2009. Areally, the model grid was 98 rows by 76 columns with a variable cell size ranging from about 1.5 to 25 acres. Smaller cells were used to represent the reservoir to accurately simulate the reservoir bathymetry and nearby monitoring wells; larger

  6. Proposal of a micromagnetic standard problem for ferromagnetic resonance simulations

    NASA Astrophysics Data System (ADS)

    Baker, Alexander; Beg, Marijan; Ashton, Gregory; Albert, Maximilian; Chernyshenko, Dmitri; Wang, Weiwei; Zhang, Shilei; Bisotti, Marc-Antonio; Franchin, Matteo; Hu, Chun Lian; Stamps, Robert; Hesjedal, Thorsten; Fangohr, Hans

    2017-01-01

    Nowadays, micromagnetic simulations are a common tool for studying a wide range of different magnetic phenomena, including the ferromagnetic resonance. A technique for evaluating reliability and validity of different micromagnetic simulation tools is the simulation of proposed standard problems. We propose a new standard problem by providing a detailed specification and analysis of a sufficiently simple problem. By analyzing the magnetization dynamics in a thin permalloy square sample, triggered by a well defined excitation, we obtain the ferromagnetic resonance spectrum and identify the resonance modes via Fourier transform. Simulations are performed using both finite difference and finite element numerical methods, with OOMMF and Nmag simulators, respectively. We report the effects of initial conditions and simulation parameters on the character of the observed resonance modes for this standard problem. We provide detailed instructions and code to assist in using the results for evaluation of new simulator tools, and to help with numerical calculation of ferromagnetic resonance spectra and modes in general.

  7. Three-dimensional numerical reservoir simulation of the EGS Demonstration Project at The Geysers geothermal field

    NASA Astrophysics Data System (ADS)

    Borgia, Andrea; Rutqvist, Jonny; Oldenburg, Curt M.; Hutchings, Lawrence; Garcia, Julio; Walters, Mark; Hartline, Craig; Jeanne, Pierre; Dobson, Patrick; Boyle, Katie

    2013-04-01

    -isothermal porous media numerical flow simulator in order to model the evolution and injection-related operational dynamics of The Geysers geothermal field. At the bottom of the domain in the felsite, we impose a constant temperature, constant saturation, low-permeability boundary. Laterally we set no-flow boundaries (no mass or heat flow), while at the top we use a fully aqueous-phase-saturated constant atmospheric pressure boundary condition. We compute initial conditions for two different conceptual models. The first conceptual model has two phases (gas and aqueous) with decreasing proportions of gas from the steam zone downward; the second model has dry steam all the way from the steam zone to the bottom. The first may be more similar to a pre-exploitation condition, before production reduced pressure and dried out the system, while the second is calibrated to the pressure and temperature actually measured in the reservoir today. Our preliminary results are in reasonable agreement with the pressure monitoring at Prati State 31. These results will be used in hydrogeomechanical modeling to plan, design, and validate the effects of injection in the system.

  8. Numerical simulation of ultrasonic wave transmission experiments in rocks of shale gas reservoirs

    NASA Astrophysics Data System (ADS)

    Chen, Qiao; Yao, Guanghua; Zhu, Honglin; Tan, Yanhu; Xu, Fenglin

    2017-01-01

    Shale gas reservoirs have risen in importance in China's new power source exploration and development program. The investigation of the propagation of ultrasonic waves in shale forms the basis for the full waveform application of acoustic logging data to the exploration of shale gas. Using acoustic wave theory, initial conditions, vibration source conditions, and stability conditions are developed in combination with experimental background of ultrasonic wave transmission. With improved boundary conditions, we performed numerical simulations of the ultrasound transmission experiments in shale using the high-order staggered-grid finite difference method (second-order in the time domain and fourth-order in the space domain). With programs developed within MatLab, the results obtained from numerical simulations agree well with experimental results based on physical models. In addition, using snapshots of the wave field that give a microscopic perspective, the propagation laws for ultrasonic waves can be analyzed. Using this method, human error is avoided, transmission experiments costs can be reduced and efficiency improved. This method extends the scope of experimental investigations regarding the transmission of ultrasonic waves in a shale gas reservoir with increasing stratification, and thus has great theoretical value and practical significance.

  9. Geothermal reservoir engineering computer code comparison and validation

    SciTech Connect

    Faust, C.R.; Mercer, J.W.; Miller, W.J.

    1980-11-12

    The results of computer simulations for a set of six problems typical of geothermal reservoir engineering applications are presented. These results are compared to those obtained by others using similar geothermal reservoir simulators on the same problem set. The purpose of this code comparison is to check the performance of participating codes on a set of typical reservoir problems. The results provide a measure of the validity and appropriateness of the simulators in terms of major assumptions, governing equations, numerical accuracy, and computational procedures. A description is given of the general reservoir simulator - its major assumptions, mathematical formulation, and numerical techniques. Following the description of the model is the presentation of the results for the six problems. Included with the results for each problem is a discussion of the results; problem descriptions and result tabulations are included in appendixes. Each of the six problems specified in the contract was successfully simulated. (MHR)

  10. Hydrothermal simulation of a fractured carbonate reservoir in southern Italy and automated detections of optimal positions for geothermal doublet installations

    NASA Astrophysics Data System (ADS)

    Niederau, Jan; Gomez, Sergio; Ebigbo, Anozie; Inversi, Barbara; Marquart, Gabriele; Scrocca, Davide

    2015-04-01

    In this work, we present the results of hydrothermal simulations for assessing the geothermal potential of a fractured carbonate reservoir in Campania (Guardia Lombardi). Local surface heat flows of up to 90 mW/m² suggest that this area is a potential medium-enthalpy geothermal reservoir. The targeted reservoir rocks are fractured shallow-water carbonates (Jurassic to Cretaceous) of the Apulia Platform. During the Apennine orogeny, those carbonates were affected by at least two tectonic phases: Thrust-related folding of the carbonate platform due to compression followed by extension which caused major normal faulting. Based on seismic interpretation, a discretized structural model is set up, comprising the reservoir unit and the overlying sedimentary cover. The model comprises an area of 42 km × 28 km and extends to a depth of about six kilometers. Results of calibrated hydrothermal reservoir simulations suggest that free convection occurs in some parts of the reservoir. For assessing optimal locations for potential hydrothermal doublet systems, a tool was developed which uses the results of the reservoir simulationsin combination with predefined constraints. Those constraints or minimum requirements consider: a) minimum temperature for operating the doublet system, b) minimum matrix permeability allowing for a pumping rate of 40 L/s, and c) social constraints (location of cities or conservation areas, where the construction of a potential geothermal energy plant would be problematic). The optimization tool ranks possible doublet system locations by evaluating an objective function for the minimum requirements. Those locations are further used to extract smaller models from the big reservoir model and simulate the operation of a hypothetical geothermal doublet system. By assessing the optimized results, an optimal location of a geothermal energy plant would produce water with a temperature of 163 °C from a depth of almost 4 km.

  11. A virtual company concept for reservoir management

    SciTech Connect

    Martin, F.D.; Kendall, R.P.; Whitney, E.M.

    1998-12-31

    This paper describes how reservoir management problems were pursued with a virtual company concept via the Internet and World Wide Web. The focus of the paper is on the implementation of virtual asset management teams that were assembled with small independent oil companies. The paper highlights the mechanics of how the virtual team transferred data and interpretations, evaluated geological models of complex reservoirs, and used results of simulation studies to analyze various reservoir management strategies.

  12. Mineral trapping of CO2 in operated geothermal reservoirs - Numerical simulations on various scales

    NASA Astrophysics Data System (ADS)

    Kühn, Michael; Stanjek, Helge; Peiffer, Stefan; Clauser, Christoph

    2013-04-01

    A novel approach to store CO2 not only by hydrodynamic trapping within a reservoir, but to convert dissolved CO2 into the geochemically more stable form of calcite in a reaction with calcium obtained from dissolution of sulphates and alkalinity from feldspars or fly ashes is described here. The presentation gives answers to the key questions: • Where are potential geothermal reservoirs with anhydrite abundant? • Does the transfer of anhydrite into calcite work at all and what are the reaction rates? • What are probable alkalinity sources and how fast are they available? Numerical simulation is a means to quantify the entire process of CO2 storage and to deepen the understanding of the detailed chemical processes. We performed numerical simulations on multiple scales. The relevant scales reach from the micro or thin section scale (ca. 1 cm) to the reservoir scale (ca. 10 km). The idea is to provide constraints for smaller scale models from the larger scale and derive functionality from smaller scale models of processes which cannot be resolved in larger scale models, due to restrictions of discretization of the applied numerical mesh. With regard to the 3 questions above we can conclude that the combination of CO2 storage and geothermal energy production is generally feasible because candidate sites are available, anhydrite is transformable into calcite and alkalinity can be provided by fly ashes (Back et al. 2010) or even in-situ (Kühn and Clauser 2006). Based on our laboratory investigations and numerical studies we are able to estimate the storage potential for mineral trapping of CO2 in geothermal reservoirs (Kühn et al. 2009). On the one hand the maximum is unfortunately less than a million tons over the life time of a geothermal heating plant. On the other hand significant storage capacities are available in geological formations with regard to hydrodynamic trapping for millions of tonnes of carbon dioxide. This is why under the current circumstances

  13. Multiscale Snow/Icemelt Discharge Simulations into Alpine Reservoirs: adding Glacier Dynamics to a Hydrological Model

    NASA Astrophysics Data System (ADS)

    Schueller, Felix; Förster, Kristian; Hanzer, Florian; Huttenlau, Matthias; Marzeion, Ben; Strasser, Ulrich; Achleitner, Stefan; Kirnbauer, Robert

    2015-04-01

    Glacier and snow runoff in high alpine regions is an essential process in hydrological research for its high relevance on lower altitude areas and hydro-power generation. MUSICALS II (Multiscale Snow/Icemelt Discharge Simulations into Alpine Reservoirs) seeks to identify and quantify water availability and runoff in alpine headwater catchments. The focus is on future changes due to glacier retreat, altering the multi-day and seasonal runoff available for hydropower operations. Our aim is to investigate and improve runoff forecasts by coupling the semi-distributed hydrological model HQSim with a simple glacier evolution model. The glacier model MMBM (Marzeion Mass Balance Model) with its statistical nature allows for fast modelling of the dynamical properties of glaciers. We present the design of the coupled hydrological application for different hydro power headwater catchments in Tyrol. The capabilities of the glacier model to simulate the selected glaciers is shown. Simulated discharge with the original and the coupled model are compared to downstream gauge measurements. Using the multi-objective optimization algorithm AMALGAM (A Multi-ALgorithm, Genetically Adaptive Multiobjective model), we optimize the glacier module parameters fully automatically. The results show the improvements in runoff modelling for past periods, when altering of glaciated catchment parts is considered. This indicates consideration of this process is mandatory for simulating future developments.

  14. Non-equilibrium simulation of CH4 production through the depressurization method from gas hydrate reservoirs

    NASA Astrophysics Data System (ADS)

    Qorbani, Khadijeh; Kvamme, Bjørn

    2016-04-01

    Natural gas hydrates (NGHs) in nature are formed from various hydrate formers (i.e. aqueous, gas, and adsorbed phases). As a result, due to Gibbs phase rule and the combined first and second laws of thermodynamics CH4-hydrate cannot reach thermodynamic equilibrium in real reservoir conditions. CH4 is the dominant component in NGH reservoirs. It is formed as a result of biogenic degradation of biological material in the upper few hundred meters of subsurface. It has been estimated that the amount of fuel-gas reserve in NGHs exceed the total amount of fossil fuel explored until today. Thus, these reservoirs have the potential to satisfy the energy requirements of the future. However, released CH4 from dissociated NGHs could find its way to the atmosphere and it is a far more aggressive greenhouse gas than CO2, even though its life-time is shorter. Lack of reliable field data makes it difficult to predict the production potential, as well as safety of CH4 production from NGHs. Computer simulations can be used as a tool to investigate CH4 production through different scenarios. Most hydrate simulators within academia and industry treat hydrate phase transitions as an equilibrium process and those which employ the kinetic approach utilize simple laboratory data in their models. Furthermore, it is typical to utilize a limited thermodynamic description where only temperature and pressure projections are considered. Another widely used simplification is to assume only a single route for the hydrate phase transitions. The non-equilibrium nature of hydrate indicates a need for proper kinetic models to describe hydrate dissociation and reformation in the reservoir with respect to thermodynamics variables, CH4 mole-fraction, pressure and temperature. The RetrasoCodeBright (RCB) hydrate simulator has previously been extended to model CH4-hydrate dissociation towards CH4 gas and water. CH4-hydrate is added to the RCB data-base as a pseudo mineral. Phase transitions are treated

  15. Problems Caused by Microbes and Treatment Strategies Monitoring and Preventing Reservoir Souring Using Molecular Microbiological Methods (MMM)

    NASA Astrophysics Data System (ADS)

    Gittel, Antje

    The injection of seawater during the process of secondary oil recovery in offshore oilfields supplies huge amounts of sulphate to the prokaryotic reservoir communities. Together with the presence of oil organics and their degradation products as electron donors, this facilitates the enrichment and growth of sulphate-reducing prokaryotes (SRP) in the reservoir, as well as in pipings and top-side installations (Sunde and Torsvik, 2005; Vance and Thrasher, 2005). The activity of SRP causes severe economic problems due to the reactivity and toxicity of the produced hydrogen sulphide (H2S), one of the major problems being reservoir souring. Besides the use of broad-spectrum biocides or inhibitors for sulphate reduction, the addition of nitrate effectively decreased the net production of H2S in model column studies (Myhr et al., 2002; Hubert et al., 2005; Dunsmore et al., 2006) and field trials (Telang et al., 1997; Bødtker et al., 2008). The mechanisms by which nitrate addition might affect souring control are (i) the stimulation of heterotrophic nitrate-reducing bacteria (hNRB) that outcompete SRP for electron donors, (ii) the activity of nitrate-reducing, sulphide-oxidising bacteria (NR-SOB), and (iii) the inhibition of SRP by the production of nitrite and nitrous oxides (Sunde and Torsvik, 2005; Hubert and Voordouw, 2007).

  16. Coal chemistry for mechanical engineers: from macromolecular thermodynamics to reservoir simulation

    SciTech Connect

    Vyacheslav Romanov

    2007-06-15

    In pilot trials and commercial scale field demonstrations of CO{sub 2} storage in coal seams, quite often unexpected problems with coal swelling around injector and reducing injection efficiency (e.g., Allison unit in the San Juan Basin, RECOPOL in Poland, Hokkaido project in Japan, etc.) can stall or even terminate the site development. To avoid the costly mistakes with the prospective site evaluation, the state of the art in reservoir modeling needs to be improved by taking into account coal properties at the macromolecular level. The current models are based on the rock mechanics, which ignores decades of experimental and theoretical studies of interaction between coal and injected fluids. A pseudopolymer approach is introduced to the modelers as a viable alternative, especially, at medium to high fluid pressures. Further, it is discussed how the thermodynamics of CO{sub 2} dissolution in the macromolecular network of the coal matrix can be incorporated into geomechanical models. 96 refs., 4 figs.

  17. Coal Chemistry for Mechanical Engineers: From Macromolecular Thermodynamics to Reservoir Simulation

    SciTech Connect

    Romanov, V.

    2007-05-01

    In pilot trials and commercial scale field demonstrations of CO2 storage in coal seams, quite often unexpected problems with coal swelling around injector and reducing injection efficiency (e.g., Allison unit in the San Juan Basin, RECOPOL in Poland, Hokkaido project in Japan, etc.) can stall or even terminate the site development. To avoid the costly mistakes with the prospective site evaluation, the state of the art in reservoir modeling needs to be improved by taking into account coal properties at the macromolecular level. The current models are based on the rock mechanics, which ignores decades of experimental and theoretical studies of interaction between coal and injected fluids. A pseudopolymer approach is introduced to the modelers as a viable alternative, especially, at medium to high fluid pressures. Further, it is discussed how the thermodynamics of CO2 dissolution in the macromolecular network of the coal matrix can be incorporated into geomechanical models.

  18. Use of TOUGHREACT to Simulate Effects of Fluid Chemistry onInjectivity in Fractured Geothermal Reservoirs with High Ionic StrengthFluids

    SciTech Connect

    Xu, Tianfu; Zhang, Guoxiang; Pruess, Karsten

    2005-02-09

    Recent studies suggest that mineral dissolution/precipitation and clay swelling effects could have a major impact on the performance of hot dry rock (HDR) and hot fractured rock (HFR) reservoirs. A major concern is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths. A Pitzer ionic interaction model has been introduced into the publicly available TOUGHREACT code for solving non-isothermal multi-phase reactive geochemical transport problems under conditions of high ionic strength, expected in typical HDR and HFR systems. To explore chemically-induced effects of fluid circulation in these systems, we examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance. We performed a number of coupled thermo-hydrologic-chemical simulations in which the fractured medium was represented by a one-dimensional MINC model (multiple interacting continua). Results obtained with the Pitzer activity coefficient model were compared with those using an extended Debye-Hueckel equation. Our simulations show that non-ideal activity effects can be significant even at modest ionic strength, and can have major impacts on permeability evolution in injection-production systems. Alteration of injection water chemistry, for example by dilution with fresh water, can greatly alter precipitation and dissolution effects, and can offer a powerful tool for operating hot dry rock and hot fractured rock reservoirs in a sustainable manner.

  19. Reservoir Modeling by Data Integration via Intermediate Spaces and Artificial Intelligence Tools in MPS Simulation Frameworks

    SciTech Connect

    Ahmadi, Rouhollah; Khamehchi, Ehsan

    2013-12-15

    Conditioning stochastic simulations are very important in many geostatistical applications that call for the introduction of nonlinear and multiple-point data in reservoir modeling. Here, a new methodology is proposed for the incorporation of different data types into multiple-point statistics (MPS) simulation frameworks. Unlike the previous techniques that call for an approximate forward model (filter) for integration of secondary data into geologically constructed models, the proposed approach develops an intermediate space where all the primary and secondary data are easily mapped onto. Definition of the intermediate space, as may be achieved via application of artificial intelligence tools like neural networks and fuzzy inference systems, eliminates the need for using filters as in previous techniques. The applicability of the proposed approach in conditioning MPS simulations to static and geologic data is verified by modeling a real example of discrete fracture networks using conventional well-log data. The training patterns are well reproduced in the realizations, while the model is also consistent with the map of secondary data.

  20. Simulation and control problems in elastic robots

    NASA Technical Reports Server (NTRS)

    Tadikonda, S. S. K.; Baruh, H.

    1989-01-01

    Computational issues associated with modeling and control of robots with revolute joints and elastic arms are considered. A manipulator with one arm and pinned at one end is considered to investigate various aspects of the modeling procedure and the model, and the effect of coupling between the rigid-body and the elastic motions. The rigid-body motion of a manipulator arm is described by means of a reference frame attached to the shadow beam, and the linear elastic operator denoting flexibility is defined with respect to this reference frame. The small elastic motion assumption coupled with the method of assumed modes is used to model the elasticity in the arm. It is shown that only terms up to quadratic in these model amplitudes need to be retained. An important aspect of the coupling between the rigid-body and the elastic motion is the centrifugal stiffening effect. This effect stiffens the elastic structure, as to be expected on physical grounds, gives rise to a time-varying inertia term for the rigid-body motion, and, in general, results in an effective inertia term smaller than the rigid-body inertia term. Simulation results are presented for an elastic beam pinned at one end and free at the other, and rotating in a horizontal plane, and control issues such as the order of the model, number of sensors, and modal extraction are examined within this context.

  1. Image analysis for Validation of Simulations of Fluid Mix Problem

    SciTech Connect

    Kamath, C; Miller, P

    2007-01-10

    As computer simulations gain acceptance for the modeling of complex physical phenomena, there is an increasing need to validate these simulation codes by comparing them to experiments. Currently, this is done qualitatively, using a visual approach. This is obviously very subjective and more quantitative metrics are needed, especially to identify simulations which are closer to experiments than other simulations. In this paper, we show how image processing techniques can be effectively used in such comparisons. Using an example from the problem of mixing of two fluids, we show that we can quantitatively compare experimental and simulation images by extracting higher level features to characterize the objects in the images.

  2. Simulating reservoir releases to mitigate climate impacts on fish sustainability below Shasta Lake using stochastic and mechanistic modeling approaches

    NASA Astrophysics Data System (ADS)

    Sapin, J. R.; Saito, L.; Rajagopalan, B.; Caldwell, R. J.

    2013-12-01

    Preservation of the Chinook salmon fishery on the Sacramento River in California has been a major concern since the winter-run Chinook was listed as threatened in 1989. The construction of Shasta Dam and Reservoir in 1945 prevented the salmon from reaching their native cold-water spawning habitat, resulting in severe population declines. The temperature control device (TCD) installed at Shasta Dam in 1997 provides increased capabilities of supplying cold-water habitat downstream of the dam to stimulate salmon spawning. However, increased air temperatures due to climate change could make it more difficult to meet downstream temperature targets with the TCD. By coupling stochastic hydroclimatology generation with two-dimensional hydrodynamic modeling of the reservoir we can simulate TCD operations under extreme climate conditions. This is accomplished by stochastically generating climate and inflow scenarios (created with historical data from NOAA, USGS and USBR) as input into a CE-QUAL-W2 model of the reservoir that can simulate TCD operations. Simulations will investigate if selective withdrawal from multiple gates of the TCD are capable of meeting temperature targets downstream of the dam under extreme hydroclimatic conditions. Moreover, our non-parametric methods for stochastically generating climate and inflow scenarios are capable of producing statistically representative years of extreme wet or extreme dry conditions beyond what is seen in the historical record. This allows us to simulate TCD operations for unprecedented hydroclimatic conditions with implications for climate changes in the watershed. Preliminary results of temperature outputs from simulations of TCD operations under extreme climate conditions with CE-QUAL-W2 will be presented. The conditions chosen for simulation are grounded to real-world managerial concerns by utilizing collaborative workshops with reservoir managers to establish which hydroclimatic scenarios would be of most concern for

  3. Simulating the gas hydrate production test at Mallik using the pilot scale pressure reservoir LARS

    NASA Astrophysics Data System (ADS)

    Heeschen, Katja; Spangenberg, Erik; Schicks, Judith M.; Priegnitz, Mike; Giese, Ronny; Luzi-Helbing, Manja

    2014-05-01

    LARS, the LArge Reservoir Simulator, allows for one of the few pilot scale simulations of gas hydrate formation and dissociation under controlled conditions with a high resolution sensor network to enable the detection of spatial variations. It was designed and built within the German project SUGAR (submarine gas hydrate reservoirs) for sediment samples with a diameter of 0.45 m and a length of 1.3 m. During the project, LARS already served for a number of experiments simulating the production of gas from hydrate-bearing sediments using thermal stimulation and/or depressurization. The latest test simulated the methane production test from gas hydrate-bearing sediments at the Mallik test site, Canada, in 2008 (Uddin et al., 2011). Thus, the starting conditions of 11.5 MPa and 11°C and environmental parameters were set to fit the Mallik test site. The experimental gas hydrate saturation of 90% of the total pore volume (70 l) was slightly higher than volumes found in gas hydrate-bearing formations in the field (70 - 80%). However, the resulting permeability of a few millidarcy was comparable. The depressurization driven gas production at Mallik was conducted in three steps at 7.0 MPa - 5.0 MPa - 4.2 MPa all of which were used in the laboratory experiments. In the lab the pressure was controlled using a back pressure regulator while the confining pressure was stable. All but one of the 12 temperature sensors showed a rapid decrease in temperature throughout the sediment sample, which accompanied the pressure changes as a result of gas hydrate dissociation. During step 1 and 2 they continued up to the point where gas hydrate stability was regained. The pressure decreases and gas hydrate dissociation led to highly variable two phase fluid flow throughout the duration of the simulated production test. The flow rates were measured continuously (gas) and discontinuously (liquid), respectively. Next to being discussed here, both rates were used to verify a model of gas

  4. The Diffusion Simulator - Teaching Geomorphic and Geologic Problems Visually.

    ERIC Educational Resources Information Center

    Gilbert, R.

    1979-01-01

    Describes a simple hydraulic simulator based on more complex models long used by engineers to develop approximate solutions. It allows students to visualize non-steady transfer, to apply a model to solve a problem, and to compare experimentally simulated information with calculated values. (Author/MA)

  5. Implict Monte Carlo Radiation Transport Simulations of Four Test Problems

    SciTech Connect

    Gentile, N

    2007-08-01

    Radiation transport codes, like almost all codes, are difficult to develop and debug. It is helpful to have small, easy to run test problems with known answers to use in development and debugging. It is also prudent to re-run test problems periodically during development to ensure that previous code capabilities have not been lost. We describe four radiation transport test problems with analytic or approximate analytic answers. These test problems are suitable for use in debugging and testing radiation transport codes. We also give results of simulations of these test problems performed with an Implicit Monte Carlo photonics code.

  6. Conformity assessment for seismic monitoring and reservoir simulation at the Ketzin pilot site - how much conformity can be reached?

    NASA Astrophysics Data System (ADS)

    Lüth, Stefan; Ivanova, Alexandra; Kempka, Thomas

    2016-04-01

    The EU CCS Directive defines three high-level criteria which have to be fulfilled by a site operator in the post closure phase of a storage site before liability can be transferred to the public after site closure. One of these high-level requirements is "Demonstrating conformity between observed and simulated plume behaviour". The observed plume behaviour is derived from geophysical and/or geochemical monitoring. Repeated 3D seismic observations have proven to provide the most comprehensive image of a CO2 plume in various projects such as Sleipner, Weyburn, or Ketzin. The simulated plume behaviour is derived from reservoir simulation using a model calibrated with monitoring results. Plume observations using any monitoring method are always affected by limited resolution and detection ability, and reservoir simulations will only be able to provide an approximated representation of the occurring reservoir processes. Therefore, full conformity between observed and simulated plume behaviour is difficult to achieve, if it is at all. It is therefore of crucial importance for each storage site to understand to what degree conformity can be achieved under realistic conditions, comprising noise affected monitoring data and reservoir models based on geological uncertainties. We applied performance criteria (plume footprint area, lateral migration distance, plume volume, and similarity index) for a comparison between monitoring results (4D seismic measurements) and reservoir simulations, considering a range of seismic amplitude values as noise threshold and a range of minimum thickness of the simulated CO2 plume. Relating the performance criteria to the noise and thickness threshold values allows assessing the quality of conformance between simulated and observed behaviour of a CO2 plume. The Ketzin site is provided with a comprehensive monitoring data set and a history-matched reservoir model. Considering the relatively high noise level, which is inherent for land

  7. A Simulated Research Problem for Undergraduate Metamorphic Petrology.

    ERIC Educational Resources Information Center

    Amenta, Roddy V.

    1984-01-01

    Presents a laboratory problem in metamorphic petrology designed to simulate a research experience. The problem deals with data on scales ranging from a geologic map to hand specimens to thin sections. Student analysis includes identifying metamorphic index minerals, locating their isograds on the map, and determining the folding sequence. (BC)

  8. THE ITA PROBLEM: A Ready-to-Use Simulation

    ERIC Educational Resources Information Center

    Halleck, Gene B.

    2008-01-01

    This simulation probes what is known as the "foreign" teaching assistant problem. The "problem" can be found at large state universities in the United States where international graduate students are required to earn their scholarships by teaching undergraduate courses and arises because of a combination of issues, including…

  9. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

    NASA Astrophysics Data System (ADS)

    Reagan, Matthew T.; Moridis, George J.; Keen, Noel D.; Johnson, Jeffrey N.

    2015-04-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.

  10. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport.

    PubMed

    Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

    2015-04-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes.

  11. Simulation-based inexact chance-constrained nonlinear programming for eutrophication management in the Xiangxi Bay of Three Gorges Reservoir.

    PubMed

    Huang, Y L; Huang, G H; Liu, D F; Zhu, H; Sun, W

    2012-10-15

    Although integrated simulation and optimization approaches under stochastic uncertainty have been applied to eutrophication management problems, few studies are reported in eutrophication control planning where multiple formats of uncertainties and nonlinearities are addressed in forms of intervals and probabilistic distributions within an integrated framework. Since the impounding of Three Gorges Reservoir (TGR), China in 2003, the hydraulic conditions and aquatic environment of the Xiangxi Bay (XXB) have changed significantly. The resulting emergence of eutrophication and algal blooms leads to its deteriorated water quality. The XXB becomes an ideal case study area. Thus, a simulation-based inexact chance-constrained nonlinear programming (SICNP) model is developed and applied to eutrophication control planning in the XXB of the TGR under uncertainties. In the SICNP, the wastewater treatment costs for removing total phosphorus (TP) are set as the objective function; effluent discharge standards, stream water quality standards and eutrophication control standards are considered in the constraints; a steady-state simulation model for phosphorus transport and fate is embedded in the environmental standards constraints; the interval programming and chance-constrained approaches are integrated to provide interval decision variables but also the associated risk levels in violating the system constraints. The model results indicate that changes in the violating level (q) will result in different strategy distributions at spatial and temporal scales; the optimal value of cost objective is from [2.74, 13.41] million RMB to [2.25, 13.08] million RMB when q equals from 0.01 to 0.25; the required TP treatment efficiency for the Baisha plant is the most stringent, which is followed by the Xiakou Town and the Zhaojun Town, while the requirement for the Pingyikou cement plant is the least stringent. The model results are useful for making optimal policies on eutrophication

  12. Modeling naturally fractured reservoirs: From experimental rock mechanics to flow simulation

    NASA Astrophysics Data System (ADS)

    Rijken, Margaretha Catharina Maria

    Fractures have a big impact on reservoir production but are inherently difficult to quantify. This study gives a robust and practical workflow to obtain a mechanically consistent naturally fractured reservoir model without direct sampling of the fracture network. The three tiers of the workflow are: (1) subcritical testing, (2) geomechanical modeling, and (3) flow modeling. Subcritical fracture index, a rock property, has been shown to influence fracture attributes such as length, spacing and connectivity. Subcritical tests show that the average subcritical index for sandstones in ambient air is around 62, whereas the average value for microstructurally comparable carbonates samples is 120. Thin-section analysis shows that an increase in cement content increases the subcritical index. Furthermore, sandstone samples containing more than 15% carbonate cement, sandstone samples containing more than 40% clay, and pure carbonate samples exhibit a large drop in subcritical index when the environment is changed from ambient air or oil to fresh water or brine. Geomechanical modeling has shown that the mechanical bed thickness has a large influence on fracture pattern characteristics and has the potential to overshadow fracture pattern changes due to strain level, strain anisotropy and subcritical index. Furthermore, an increase in strain anisotropy reduces the number of dominant through-going fracture sets and decreases the fracture spacing between the through-going fractures. This spacing variation not only influences the preferential drainage direction, it can also enhance the drainage efficiency, because more rock is exposed to the through-going fractures which are more likely to be intersected by a borehole. The level of detail provided by the geomechanical model greatly exceeds the level of detail normally used in reservoir simulation. Therefore, upscaling of the geomechanically generated fracture patterns is necessary for practical flow modeling. This study shows

  13. Simulation of commercial scale CO2 injection into a fracture reservoir

    NASA Astrophysics Data System (ADS)

    Li, Y.; Li, S.; Zhang, Y.

    2011-12-01

    Geologic Carbon Sequestration is a proposed means to reduce atmospheric concentration of carbon dioxide (CO2). At Teapot Dome, Wyoming, CO2 will be injected into the Tensleep Formation, a depleted oil reservoir characterized with significant heterogeneity including facies, faults, and fractures. We've collected geological and engineering characterization data of the entire Teapot Dome field, including core data, well logs, seismic data, and production records. All data were screened for accuracy, before subsets of the data are used to build a geologic reservoir model. A formation structural model is created first by interpreting faults and stratigraphy from 3D seismic data. Formation MicroImager logs are analyzed for fracture characteristics to generate in-situ fracture intensity at wells, which is subsequently interpolated throughout the model with kriging. Based on the intensity and a set of geometric fracture parameters (constrained by outcrop and core measurements), a 3D stochastic Discrete Fracture Network (DFN) is created. One realization of the DFN is upscaled to a dual-porosity simulation model using a variant of the Oda's method. This method upscales the fracture network to an effective grid-block fracture permeability. To account for fluid transfer from matrix to fracture, a sigma factor is computed using average fracture spacings within the grid block. Matrix porosity is populated in the model by kriging interpolation of well-log-derived values. With the dual-porosity model, CO2 is injected near the crest of the dome (the proposed location) at a rate of 2.6 Mt/year for 50 years, with an injection bottomhole pressure set at 160% hydrostatic pressure. Boundary of the model is open except along one bounding fault assumed sealed. Results of the simulation suggest that provided that fluid pressure buildup is not an issue (simulated pressure buildup near the fault is minor), the Tensleep Formation at Teapot Dome can sustain commercial-scale injection over time

  14. Noble gas and hydrocarbon tracers in multiphase unconventional hydrocarbon systems: Toward integrated advanced reservoir simulators

    NASA Astrophysics Data System (ADS)

    Darrah, T.; Moortgat, J.; Poreda, R. J.; Muehlenbachs, K.; Whyte, C. J.

    2015-12-01

    Although hydrocarbon production from unconventional energy resources has increased dramatically in the last decade, total unconventional oil and gas recovery from black shales is still less than 25% and 9% of the totals in place, respectively. Further, the majority of increased hydrocarbon production results from increasing the lengths of laterals, the number of hydraulic fracturing stages, and the volume of consumptive water usage. These strategies all reduce the economic efficiency of hydrocarbon extraction. The poor recovery statistics result from an insufficient understanding of some of the key physical processes in complex, organic-rich, low porosity formations (e.g., phase behavior, fluid-rock interactions, and flow mechanisms at nano-scale confinement and the role of natural fractures and faults as conduits for flow). Noble gases and other hydrocarbon tracers are capably of recording subsurface fluid-rock interactions on a variety of geological scales (micro-, meso-, to macro-scale) and provide analogs for the movement of hydrocarbons in the subsurface. As such geochemical data enrich the input for the numerical modeling of multi-phase (e.g., oil, gas, and brine) fluid flow in highly heterogeneous, low permeability formations Herein we will present a combination of noble gas (He, Ne, Ar, Kr, and Xe abundances and isotope ratios) and molecular and isotopic hydrocarbon data from a geographically and geologically diverse set of unconventional hydrocarbon reservoirs in North America. Specifically, we will include data from the Marcellus, Utica, Barnett, Eagle Ford, formations and the Illinois basin. Our presentation will include geochemical and geological interpretation and our perspective on the first steps toward building an advanced reservoir simulator for tracer transport in multicomponent multiphase compositional flow (presented separately, in Moortgat et al., 2015).

  15. Numerical simulations of the Macondo well blowout reveal strong control of oil flow by reservoir permeability and exsolution of gas.

    PubMed

    Oldenburg, Curtis M; Freifeld, Barry M; Pruess, Karsten; Pan, Lehua; Finsterle, Stefan; Moridis, George J

    2012-12-11

    In response to the urgent need for estimates of the oil and gas flow rate from the Macondo well MC252-1 blowout, we assembled a small team and carried out oil and gas flow simulations using the TOUGH2 codes over two weeks in mid-2010. The conceptual model included the oil reservoir and the well with a top boundary condition located at the bottom of the blowout preventer. We developed a fluid properties module (Eoil) applicable to a simple two-phase and two-component oil-gas system. The flow of oil and gas was simulated using T2Well, a coupled reservoir-wellbore flow model, along with iTOUGH2 for sensitivity analysis and uncertainty quantification. The most likely oil flow rate estimated from simulations based on the data available in early June 2010 was about 100,000 bbl/d (barrels per day) with a corresponding gas flow rate of 300 MMscf/d (million standard cubic feet per day) assuming the well was open to the reservoir over 30 m of thickness. A Monte Carlo analysis of reservoir and fluid properties provided an uncertainty distribution with a long tail extending down to 60,000 bbl/d of oil (170 MMscf/d of gas). The flow rate was most strongly sensitive to reservoir permeability. Conceptual model uncertainty was also significant, particularly with regard to the length of the well that was open to the reservoir. For fluid-entry interval length of 1.5 m, the oil flow rate was about 56,000 bbl/d. Sensitivity analyses showed that flow rate was not very sensitive to pressure-drop across the blowout preventer due to the interplay between gas exsolution and oil flow rate.

  16. Numerical simulations of the Macondo well blowout reveal strong control of oil flow by reservoir permeability and exsolution of gas

    PubMed Central

    Oldenburg, Curtis M.; Freifeld, Barry M.; Pruess, Karsten; Pan, Lehua; Finsterle, Stefan; Moridis, George J.

    2012-01-01

    In response to the urgent need for estimates of the oil and gas flow rate from the Macondo well MC252-1 blowout, we assembled a small team and carried out oil and gas flow simulations using the TOUGH2 codes over two weeks in mid-2010. The conceptual model included the oil reservoir and the well with a top boundary condition located at the bottom of the blowout preventer. We developed a fluid properties module (Eoil) applicable to a simple two-phase and two-component oil-gas system. The flow of oil and gas was simulated using T2Well, a coupled reservoir-wellbore flow model, along with iTOUGH2 for sensitivity analysis and uncertainty quantification. The most likely oil flow rate estimated from simulations based on the data available in early June 2010 was about 100,000 bbl/d (barrels per day) with a corresponding gas flow rate of 300 MMscf/d (million standard cubic feet per day) assuming the well was open to the reservoir over 30 m of thickness. A Monte Carlo analysis of reservoir and fluid properties provided an uncertainty distribution with a long tail extending down to 60,000 bbl/d of oil (170 MMscf/d of gas). The flow rate was most strongly sensitive to reservoir permeability. Conceptual model uncertainty was also significant, particularly with regard to the length of the well that was open to the reservoir. For fluid-entry interval length of 1.5 m, the oil flow rate was about 56,000 bbl/d. Sensitivity analyses showed that flow rate was not very sensitive to pressure-drop across the blowout preventer due to the interplay between gas exsolution and oil flow rate. PMID:21730177

  17. Numerical Simulations and Tracer Studies as a Tool to Support Water Circulation Modeling in Breeding Reservoirs

    NASA Astrophysics Data System (ADS)

    Zima, Piotr

    2014-12-01

    The article presents a proposal of a method for computer-aided design and analysis of breeding reservoirs in zoos and aquariums. The method applied involves the use of computer simulations of water circulation in breeding pools. A mathematical model of a pool was developed, and a tracer study was carried out. A simplified model of two-dimensional flow in the form of a biharmonic equation for the stream function (converted into components of the velocity vector) was adopted to describe the flow field. This equation, supplemented by appropriate boundary conditions, was solved numerically by the finite difference method. Next, a tracer migration equation was solved, which was a two-dimensional advection-dispersion equation describing the unsteady transport of a non-active, permanent solute. In order to obtain a proper solution, a tracer study (with rhodamine WT as a tracer) was conducted in situ. The results of these measurements were compared with numerical solutions obtained. The results of numerical simulations made it possible to reconstruct water circulation in the breading pool and to identify still water zones, where water circulation was impeded.

  18. A Circuit Simulation Technique for Congested Network Traffic Assignment Problem

    NASA Astrophysics Data System (ADS)

    Cho, Hsun-Jung; Huang, Heng

    2007-12-01

    The relation between electrical circuit and traffic network has been proposed by Sasaki and Inouye, but they proposed link cost function is a linear function which cannot present the congestion situation. Cho and Huang extended the link cost function to a nonlinear function which can explain the congested network. In this paper, we proposed a foremost and novel approach to solve the traffic assignment problem (TAP) by simulating the electrical circuit network which consists of nonlinear link cost function models. Comparing with the solutions of Frank-Wolfe algorithm, the simulation results are nearly identical. Thus, the simulation of a network circuit model can be applied to solve network traffic assignment problems. Finally, two examples are proposed, and the results confirmed that electrical circuit simulation is workable in solving congested network traffic assignment problems.

  19. Characterization of Anaerobic Chemical Processes in Reservoirs: Problem Description and Conceptual Model Formulation.

    DTIC Science & Technology

    1981-04-01

    CHARACTERIZATION OF ANAEROBIC CHEMICAL PROCESSES IN RESERVOIRS...ETC(U) APR al D GUNNISON, J M BRANNON UNCLASSIFIED WES/TR/E-8i-6 L 1111 1.01115 32...INISTRUCTIONS REPORT DOCUMENTATION PAGE RECINT. COMSPLETIG FORM 4. TIL adSb~)S. TYPE Of REPORT G PERIOD COySRED OIARACTERIZATION OFAAEROBIC QEMICAL...Engineers, U. S. Army Ap(J%8 Washington, D . C. 2031480r J 14. MONITORING AGENCY NAME & ADORESS(f different bass Conti.IIing Office) 1S. SECURITY CLASS

  20. Intercomparison of simulation models for CO{sub 2} disposal in underground storage reservoirs

    SciTech Connect

    Pruess, K.; Tsang, C.F.; Law, D.; Oldenburg, C.

    2001-01-01

    An intercomparison study between simulation codes for terrestrial sequestration of CO{sub 2} is proposed. The objectives are, on the one hand, to focus and evaluate key processes through numerical simulation and, on the other, to explore the strengths of different codes and achieve acceptance of such codes for use in the development of geologic systems for CO{sub 2} disposal. This will be carried out through the study of a series of test problems by groups using their simulation codes. A progression from simple and uncoupled to increasingly complex and coupled problems is envisioned. The proposed study will attempt to involve interested technical groups worldwide, and will proceed through an iterative process of problem definition, solution comparison, discussion and refinement. The Internet will be used as a medium for communicating and organizing activities, and for a flexible exchange of information and documentation of results. In addition, it is planned to hold a series of workshops. The present write-up includes an initial set of eight proposed test problems and represents the first step in the process. Readers are encouraged to communicate with us at the email address above to indicate their interest and to provide suggestions and input.

  1. Development of a compositional model fully coupled with geomechanics and its application to tight oil reservoir simulation

    NASA Astrophysics Data System (ADS)

    Xiong, Yi

    Tight oil reservoirs have received great attention in recent years as unconventional and promising petroleum resources; they are reshaping the U.S. crude oil market due to their substantial production. However, fluid flow behaviors in tight oil reservoirs are not well studied or understood due to the complexities in the physics involved. Specific characteristics of tight oil reservoirs, such as nano-pore scale and strong stress-dependency result in complex porous medium fluid flow behaviors. Recent field observations and laboratory experiments indicate that large effects of pore confinement and rock compaction have non-negligible impacts on the production performance of tight oil reservoirs. On the other hand, there are approximations or limitations for modeling tight oil reservoirs under the effects of pore confinement and rock compaction with current reservoir simulation techniques. Thus this dissertation aims to develop a compositional model coupled with geomechanics with capabilities to model and understand the complex fluid flow behaviors of multiphase, multi-component fluids in tight oil reservoirs. MSFLOW_COM (Multiphase Subsurface FLOW COMpositional model) has been developed with the capability to model the effects of pore confinement and rock compaction for multiphase fluid flow in tight oil reservoirs. The pore confinement effect is represented by the effect of capillary pressure on vapor-liquid equilibrium (VLE), and modeled with the VLE calculation method in MSFLOW_COM. The fully coupled geomechanical model is developed from the linear elastic theory for a poro-elastic system and formulated in terms of the mean stress. Rock compaction is then described using stress-dependent rock properties, especially stress-dependent permeability. Thus MSFLOW_COM has the capabilities to model the complex fluid flow behaviors of tight oil reservoirs, fully coupled with geomechanics. In addition, MSFLOW_COM is validated against laboratory experimental data, analytical

  2. Simulation of reservoir storage and firm yields of three surface-water supplies, Ipswich River Basin, Massachusetts

    USGS Publications Warehouse

    Zarriello, Phillip J.

    2002-01-01

    A Hydrologic Simulation Program FORTRAN (HSPF) model previously developed for the Ipswich River Basin was modified to simulate the hydrologic response and firm yields of the water-supply systems of Lynn, Peabody, and Salem-Beverly. The updated model, expanded to include a portion of the Saugus River Basin that supplies water to Lynn, simulated reservoir system storage over a 35-year period (1961-95) under permitted withdrawals and hypothetical restrictions designed to maintain seasonally varied streamflow for aquatic habitat. A firm yield was calculated for each system and each withdrawal restriction by altering demands until the system failed. This is considered the maximum withdrawal rate that satisfies demands, but depletes reservoir storage. Simulations indicate that, under the permitted withdrawals, Lynn and Salem-Beverly were able to meet demands and generally have their reservoir system recover to full capacity during most years; reservoir storage averaged 83 and 82 percent of capacity, respectively. The firm yields for the Lynn and Salem-Beverly systems were 11.4 and 12.2 million gallons per day (Mgal/d), respectively, or 8 and 21 percent more than average 1998-2000 demands, respectively. Under permitted withdrawals and average 1998-2000 demands, the Peabody system failed in all years; thus Peabody purchased water to meet demands. The firm yield for the Peabody system is 3.70 Mgal/d, or 37 percent less than the average 1998-2000 demand. Simulations that limit withdrawals to levels recommended by the Ipswich River Fisheries Restoration Task Group (IRFRTG) indicate that under average 1998-2000 demands, reservoir storage was depleted in each of the three systems. Reservoir storage under average 1998-2000 demands and IRFRTG-recommended streamflow requirements averaged 15, 22, and 71 percent of capacity for the Lynn, Peabody, Salem-Beverly systems, respectively. The firm-yield estimates under the IRFRTG-recommended streamflow requirements were 6.02, 1.94, and 7

  3. Geological and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir

    SciTech Connect

    M. Lee Allison

    1997-03-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reser v oir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similiar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined . Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations . Transfer of the project results to the petroleum industry is an integral component of the project. Four activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone in the Ivie Creek case-study area: (1) geostatistics, (2) field description of clinoform bounding surfaces, (3) reservoir modeling, and (4) technology transfer.

  4. Application of advanced reservoir characterization, simulation, and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, West Texas (Delaware Basin). Quarterly report, October 1 - December 31, 1996

    SciTech Connect

    Dutton, S.P.

    1997-01-01

    The objective of this project is to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. Project objectives are divided into two major phases. The objectives of the reservoir characterization phase of the project are to provide a detailed understanding of the architecture and heterogeneity of two fields, the Ford Geraldine unit and Ford West field, which produce from the Bell Canyon and Cherry Canyon Formations, respectively, of the Delaware Mountain Group and to compare Bell Canyon and Cherry Canyon reservoirs. Reservoir characterization will utilize 3-D seismic data, high-resolution sequence stratigraphy, subsurface field studies, outcrop characterization, and other techniques. Once the reservoir-characterization study of both fields is completed, a pilot area of approximately 1 mi{sup 2} in one of the fields will be chosen for reservoir simulation. The objectives of the implementation phase of the project are to (1) apply the knowledge gained from reservoir characterization and simulation studies to increase recovery from the pilot area, (2) demonstrate that economically significant unrecovered oil remains in geologically resolvable untapped compartments, and (3) test the accuracy of reservoir characterization and flow simulation as predictive tools in resource preservation of mature fields. A geologically designed, enhanced-recovery program (CO{sub 2} flood, waterflood, or polymer flood) and well-completion program will be developed, and one to three infill wells will be drilled and cored. Technical progress is summarized for: geophysical characterization; reservoir characterization; outcrop characterization; and recovery technology identification and analysis.

  5. Application of advanced reservoir characterization, simulation, and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, West Texas (Delaware Basin). Quarterly report, April 1,1996 - June 30, 1996

    SciTech Connect

    Dutton, S.P.

    1996-07-01

    The objective of this project is to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. Project objectives are divided into two major phases. The objectives of the reservoir characterization phase of the project are to provide a detailed understanding of the architecture and heterogeneity of two fields, the Ford Geraldine unit and Ford West field, which produce from the Bell Canyon and Cherry Canyon Formations, respectively, of the Delaware Mountain Group and to compare Bell Canyon and Cherry Canyon reservoirs. Reservoir characterization will utilize 3-D seismic data, high-resolution sequence stratigraphy, subsurface field studies, outcrop characterization, and other techniques. Once the reservoir- characterization study of both fields is completed, a pilot area of approximately 1 mi{sup 2} in one of the fields will be chosen for reservoir simulation. The objectives of the implementation phase of the project are to (1) apply the knowledge gained from reservoir characterization and simulation studies to increase recovery from the pilot area, (2) demonstrate that economically significant unrecovered oil remains in geologically resolvable untapped compartments, and (3) test the accuracy of reservoir characterization and flow simulation as predictive tools in resource preservation of mature fields. A geologically designed, enhanced-recovery program (CO{sub 2} flood, waterflood, or polymer flood) and well-completion program will be developed, and one to three infill wells will be drilled and cored. Progress to date is summarized for reservoir characterization.

  6. A comparative study of three simulation optimization algorithms for solving high dimensional multi-objective optimization problems in water resources

    NASA Astrophysics Data System (ADS)

    Schütze, Niels; Wöhling, Thomas; de Play, Michael

    2010-05-01

    Some real-world optimization problems in water resources have a high-dimensional space of decision variables and more than one objective function. In this work, we compare three general-purpose, multi-objective simulation optimization algorithms, namely NSGA-II, AMALGAM, and CMA-ES-MO when solving three real case Multi-objective Optimization Problems (MOPs): (i) a high-dimensional soil hydraulic parameter estimation problem; (ii) a multipurpose multi-reservoir operation problem; and (iii) a scheduling problem in deficit irrigation. We analyze the behaviour of the three algorithms on these test problems considering their formulations ranging from 40 up to 120 decision variables and 2 to 4 objectives. The computational effort required by each algorithm in order to reach the true Pareto front is also analyzed.

  7. Simulation of spatial and temporal distributions of non-point source pollution load in the Three Gorges Reservoir Region.

    PubMed

    Shen, Zhenyao; Qiu, Jiali; Hong, Qian; Chen, Lei

    2014-09-15

    Non-point source (NPS) pollution has become the largest threat to water quality in recent years. Major pollutants, particularly from agricultural activities, which include nitrogen, phosphorus and sediment that have been released into aquatic environments, have caused a range of problems in the Three Gorges Reservoir Region (TGRR), China. It is necessary to identify the spatial and temporal distributions of NPS pollutants and the highly polluted areas for the purpose of watershed management. In this study, the NPS pollutant load was simulated using the Soil and Water Assessment Tool (SWAT) and the small-scale watershed extended method (SWEM). The simulation results for four typical small catchments were extended to the entire watershed leading to estimates of the NPS load from 2001 to 2009. The results demonstrated that the NPS pollution load in the western area was the highest and that agricultural land was the primary pollutant source. The similar annual variation trends of runoff and sediment loads demonstrated that the sediment load was closely related to runoff. The loads of total nitrogen (TN) and total phosphorus (TP) were relatively stable from 2001 to 2007, except for high loads in 2006. The increase in pollution source strength was an important reason for the significant upward trend of TN and TP loads from 2008 to 2009. The rainfall from April to October contributed to the largest amount of runoff, sediment and nutrient loads for the year. The NPS load intensities in each sub-basin reveal large variations in the spatial distribution of different pollutants. It was shown that the temporal and spatial distributions of pollutant loads were positively correlated with the annual rainfall amounts and with human activities. Furthermore, this finding illustrates that conservation practices and nutrient management should be implemented in specific sites during special periods for the purpose of NPS pollution control in the TGRR.

  8. Simulation of Sediment Transport Caused by Landslide at Nanhua Reservoir Watershed in Southern Taiwan

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Hsi; Huang, Cong-Gi; Lin, Huan-Hsuan

    2016-04-01

    As a result of heavy rainfall, steep topography, young and weak geological formations, earthquakes, loose soils, slope land cultivation and other human disturbance, much area in Taiwan are prone to the occurrence of disastrous mass movements such as landslides and sediment disasters. During recent years, the extreme rainfall events brought huge amounts of rainfall and triggered severe changes in watershed environments. Typhoon Morakot in August 2009 caused severe landslides, debris flow, flooding and sediment disasters induced by record-break rainfall. The maximum rainfall of mountain area in Chiayi, Tainan, Kaohsiung and Pingtung County were over 2,900 mm. The study area is located at Nanhua reservoir watershed in southern Taiwan. The numerical model (HEC-RAS 4.1 and FLO-2D) will be used to simulate the sediment transport caused by landslide and the study will find out the separating location of erosion and deposition in the river, the danger area of riverbank, and the safety of the river terrace village under the return period of 50-year, 100-year and 200-year (such as Typhoon Morakot). The results of this study can provide for the disaster risk management of administrative decisions to lessen the impacts of natural hazards and may also be useful for time-space variation of sediment disasters caused by Climate Change.

  9. [Problem in the hygienic regulation and standardization of biotechnological strains in reservoir water].

    PubMed

    Sheina, N I; Zholdakova, Z I; Ivanov, N G

    2010-01-01

    The pattern of the negative effect of biotechnological strains belonging to different taxons was experimentally studied. The effect of the strains manifested as imbalance of immunocompetent cells, development of immediate and delayed hypersensitivity, and altered qualitative and quantitative characteristics of the autochtonic microflora of the intestine. The minimum acting (10(5) cells/l) and non-acting (10(4) cells/l) enteral exposure levels were determined for the bulk of the test strains. Analysis of the authors' findings and the data available in the literature made it possible to propose a study program on the hygienic regulation and standardization of industrial microorganisms and their based microbiological products in the reservoir water.

  10. Few-Body Problem: Theory and Computer Simulations

    NASA Astrophysics Data System (ADS)

    Flynn, Chris

    A conference held in honour of the 60th birthday of Professor Mauri Valtonen in Turku, Finland, 4th-9th July 2005. The conference's major themes were the few-body problem in celestial mechanics and its numerical study; the theory of few-body escape; dynamics of multiple stars; computer simulations versus observations; planetary systems and few-body dynamics, and chaos in the few-body problem.

  11. The Fermi-Pasta-Ulam problem: Simulation and modern dynamics

    SciTech Connect

    Weissert, T.P.

    1992-01-01

    In 1952, Enrico Fermi, John Pasta and Stanislaw Ulam (FPU) simulated the loaded string model, perturbed with small, nonlinear interaction terms. Because Poincare's theorem guarantees the non-existence of a complete set of integrals for three-body problem, they expected to see the diffusion of energy from its single-mode initial condition to all other modes of the string. But for every combination of initial conditions, the energy remained bounded within the lowest few modes. No theoretical explanation existed for this failure of the underlying hypothesis that erogidicity follows from the lack of a complete set of integrals of the motion in a Hamiltonian model. The author traces the history of this problem from the FPU simulation to the point that a consensus was reached concerning its solution twenty years later. During this period, the simulation of nonlinearly-perturbed integral models became the methodology for a new era in dynamics. Through the use of simulation, dynamicists discovered deterministic chaos, in which the exponential separation of pair orbits generate randomness in deterministic macroscopic systems, and a new kind of structure-related to the KAM theorem-that provides limited order in the absence of analytic integrals of the motions. The author maps the set of conceptually-related journal articles into a chronological inference topology that tracks the understanding of this problem of dynamics. Simulating non-integrable models on a digital computer requires the discretization of time and space. These approximations affect what the simulation can reveal about the model, and the model about reality. Simulations play the role of experiments on mathematical models. A discussion is presented of the issues that emerge with the use of simulation as a heuristic device and the groundwork is laid for an epistemology of simulation.

  12. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

    PubMed Central

    Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

    2015-01-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes. Key Points: Short-term leakage fractured reservoirs requires high-permeability pathways Production strategy affects the likelihood and magnitude of gas release Gas release is likely short-term, without additional driving forces PMID

  13. Application of advanced reservoir characterization, simulation, and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, West Texas (Delaware Basin). Quarterly report, July 1 - September 30, 1996

    SciTech Connect

    Dutton, S.P.

    1996-10-01

    The objective of this project is to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. Project objectives are divided into two major phases. The objectives of the reservoir characterization phase of the project are to provide a detailed understanding of the architecture and heterogeneity of two fields, the Ford Geraldine unit and Ford West field, which produce from the Bell Canyon and Cherry Canyon Formations, respectively, of the Delaware Mountain Group and to compare Bell Canyon and Cherry Canyon reservoirs. Reservoir characterization will utilize 3-D seismic data, high-resolution sequence stratigraphy, subsurface field studies, outcrop characterization, and other techniques. Once the reservoir- characterization study of both fields is completed, a pilot area of approximately 1 mi{sup 2} in one of the fields will be chosen for reservoir simulation. The objectives of the implementation phase of the project are to (1) apply the knowledge gained from reservoir characterization and simulation studies to increase recovery from the pilot area, (2) demonstrate that economically significant unrecovered oil remains in geologically resolvable untapped compartments, and (3) test the accuracy of reservoir characterization and flow simulation as predictive tools in resource preservation of mature fields. A geologically designed, enhanced-recovery program (CO{sup 2} flood, waterflood, or polymer flood) and well-completion program will be developed, and one to three infill wells will be drilled and cored. Accomplishments for this past quarter are discussed.

  14. A dual-porosity reservoir model with a nonlinear coupling term

    SciTech Connect

    Zimmerman, R.W.; Chen, G.; Hadgu, T.; Bodvarsson, G.S.

    1992-09-01

    Since their introduction by Barenblatt et al. (1960), double-porosity models have been widely used for simulating flow in fractured reservoirs, such as geothermal reservoirs. In a dual-porosity system, the matrix blocks provide most of the storage of the reservoir, whereas the fractures provide the global transmissivity. Initially, most work on dual-porosity models emphasized the development of analytical solutions to idealized reservoir problems. Increasingly, the dual-porosity approach is being implemented by numerical reservoir simulators. Accurate numerical simulation of a dual-porosity problem often requires a prohibitively large number of computational cells in order to resolve the transient pressure gradients in the matrix blocks. We discuss a new dual-porosity model that utilizes a nonlinear differential equation to approximate the fracture/matrix interactions, When implemented into a numerical simulator, it eliminates the need to discretize the matrix blocks, and thereby allows more efficient simulation of reservoir problems.

  15. Simulated monthly hydrologic data and estimated flood characteristics for Cherry Creek at a proposed reservoir site near Terry, Montana

    USGS Publications Warehouse

    Parrett, Charles; Johnson, D.R.

    1995-01-01

    A monthly hydrologic budget for water years 1937- 92 was developed for the proposed Cherry Creek Reservoir (maximum volume about 14,100 acre-feet). Monthly suspended-sediment loads and dissolved- solids concentrations in the reservoir and flood hydrographs and volumes having recurrence intervals of 25-, 50-, and 100-years were estimated. Monthly streamflow and precipitation were estimated using a mixed-station, record-extension procedure. Monthly suspended-sediment and dissolved-solids concentrations in the reservoir were estimated from regression relations between logarithms of concen- tration and streamflow. The simulation showed that flows that Cherry Creek generally were adequate to maintain the reservoir elevation above the minimum operating level for a seepage loss of 0 cubic ft per square. With a seepage loss rate of 3 cubic ft per square, diversions from the Yellowstone River were required for about on third of the months. Cumulative sediment deposition during the 56-year simulation period was about 138 acre-ft from Cherry Creek alone and was about 149 acre-ft when additional water was imported from the Yellowstone River. The concentration of dissolved solids in the reservoir reached a maximum value of about 2,540 mg/L for a seepage loss of 0 cubic ft per square. For a seepage loss of 3 cubic ft per square, water was imported from the Yellowstone River and the maximum concentration of dissolved solids was about 1,200 mg/L. Volumes for flood discharges were estimated from synthetic 24-hour duration storms that were used in a rainfall-runoff model (HEC-1).

  16. A reduced-order based CE-QUAL-W2 model for simulation of nitrate concentration in dam reservoirs

    NASA Astrophysics Data System (ADS)

    Noori, Roohollah; Yeh, Hund-Der; Ashrafi, Khosro; Rezazadeh, Najmeh; Bateni, Sayed M.; Karbassi, Abdulreza; Kachoosangi, Fatemeh Torabi; Moazami, Saber

    2015-11-01

    When the number of computational grids increases, water quality simulation complexities arise. Therefore, using a reduced order framework to express the variations of the objective parameter may facilitate the simulation task and also the interpretation of computational results. In this regard, a new reduced-order approach was proposed to link a water quality simulator model (CE-QUAL-W2, W2) with a data reduction technique (proper orthogonal decomposition, POD). The W2 model simulated spatio-temporal variations of nitrate in the Karkheh Reservoir, Iran. Thereafter, the POD model reduced the dimensions of simulated nitrate in the computational grids. The performance of the developed reduced-order model (ROM) results was evaluated through the comparison of the regenerated nitrate data by the model, and the simulated ones by W2. Findings indicated that the first four modes among 1825 computed ones by ROM conserved approximately over 91% of the nitrate variations. It means that the ROM was capable of showing the spatio-temporal variations of nitrate in the reservoir using the first few modes. Finally, confirmation of ROM indicated that the error of order of magnitude was less than 0.001, for nitrate ROM to regenerate nitrate data using 100 basis functions.

  17. Physical properties of rocks and aqueous fluids at conditions simulating near- and supercritical reservoirs

    NASA Astrophysics Data System (ADS)

    Kummerow, Juliane; Raab, Siegfried

    2016-04-01

    The growing interest in exploiting supercritical geothermal reservoirs calls for a thorough identification and understanding of physico-chemical processes occuring in geological settings with a high heat flow. In reservoir engineering, electrical sounding methods are common geophysical exploration and monitoring tools. However, a realistic interpretation of field measurements is based on the knowledge of both, the physical properties of the rock and those of the interacting fluid at defined temperature and pressure conditions. Thus, laboratory studies at simulated in-situ conditions provide a link between the field data and the material properties in the depth. The physico-chemical properties of fluids change dramatically above the critical point, which is for pure water 374.21 °C and 221.2 bar. In supercritical fluids mass transfer and diffusion-controlled chemical reactions are enhanced and cause mineral alterations. Also, ion mobility and ion concentration are affected by the change of physical state. All this cause changes in the electrical resistivity of supercritical fluids and may have considerable effects on the porosity and hydraulic properties of the rocks they are in contact with. While there are some datasets available for physical and chemical properties of water and single component salt solutions above their critical points, there exist nearly no data for electrical properties of mixed brines, representing the composition of natural geothermal fluids. Also, the impact of fluid-rock interactions on the electrical properties of multicomponent fluids in a supercritical region is scarcely investigated. For a better understanding of fluid-driven processes in a near- and supercritical geological environment, in the framework of the EU-funded FP7 program IMAGE we have measured (1) the electrical resistivity of geothermal fluids and (2) physical properties of fluid saturated rock samples at simulated in-situ conditions. The permeability and electrical

  18. The Million-Body Problem: Particle Simulations in Astrophysics

    ScienceCinema

    Rasio, Fred [Northwestern University

    2016-07-12

    Computer simulations using particles play a key role in astrophysics. They are widely used to study problems across the entire range of astrophysical scales, from the dynamics of stars, gaseous nebulae, and galaxies, to the formation of the largest-scale structures in the universe. The 'particles' can be anything from elementary particles to macroscopic fluid elements, entire stars, or even entire galaxies. Using particle simulations as a common thread, this talk will present an overview of computational astrophysics research currently done in our theory group at Northwestern. Topics will include stellar collisions and the gravothermal catastrophe in dense star clusters.

  19. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries

    NASA Astrophysics Data System (ADS)

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-09-01

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs.

  20. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries

    PubMed Central

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-01-01

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs. PMID:27628131

  1. Simulation Study of CO2-EOR in Tight Oil Reservoirs with Complex Fracture Geometries.

    PubMed

    Zuloaga-Molero, Pavel; Yu, Wei; Xu, Yifei; Sepehrnoori, Kamy; Li, Baozhen

    2016-09-15

    The recent development of tight oil reservoirs has led to an increase in oil production in the past several years due to the progress in horizontal drilling and hydraulic fracturing. However, the expected oil recovery factor from these reservoirs is still very low. CO2-based enhanced oil recovery is a suitable solution to improve the recovery. One challenge of the estimation of the recovery is to properly model complex hydraulic fracture geometries which are often assumed to be planar due to the limitation of local grid refinement approach. More flexible methods like the use of unstructured grids can significantly increase the computational demand. In this study, we introduce an efficient methodology of the embedded discrete fracture model to explicitly model complex fracture geometries. We build a compositional reservoir model to investigate the effects of complex fracture geometries on performance of CO2 Huff-n-Puff and CO2 continuous injection. The results confirm that the appropriate modelling of the fracture geometry plays a critical role in the estimation of the incremental oil recovery. This study also provides new insights into the understanding of the impacts of CO2 molecular diffusion, reservoir permeability, and natural fractures on the performance of CO2-EOR processes in tight oil reservoirs.

  2. Numerical simulation of the electrical properties of shale gas reservoir rock based on digital core

    NASA Astrophysics Data System (ADS)

    Nie, Xin; Zou, Changchun; Li, Zhenhua; Meng, Xiaohong; Qi, Xinghua

    2016-08-01

    In this paper we study the electrical properties of shale gas reservoir rock by applying the finite element method to digital cores which are built based on an advanced Markov Chain Monte Carlo method and a combination workflow. Study shows that the shale gas reservoir rock has strong anisotropic electrical conductivity because the conductivity is significantly different in both horizontal and vertical directions. The Archie formula is not suitable for application in shale reservoirs. The formation resistivity decreases in two cases; namely (a) with the increase of clay mineral content and the cation exchange capacity of clay, and (b) with the increase of pyrite content. The formation resistivity is not sensitive to the solid organic matter but to the clay and gas in the pores.

  3. Simulating quantum correlations as a distributed sampling problem

    SciTech Connect

    Degorre, Julien; Laplante, Sophie; Roland, Jeremie

    2005-12-15

    It is known that quantum correlations exhibited by a maximally entangled qubit pair can be simulated with the help of shared randomness, supplemented with additional resources, such as communication, postselection or nonlocal boxes. For instance, in the case of projective measurements, it is possible to solve this problem with protocols using one bit of communication or making one use of a nonlocal box. We show that this problem reduces to a distributed sampling problem. We give a new method to obtain samples from a biased distribution, starting with shared random variables following a uniform distribution, and use it to build distributed sampling protocols. This approach allows us to derive, in a simpler and unified way, many existing protocols for projective measurements, and extend them to positive operator value measurements. Moreover, this approach naturally leads to a local hidden variable model for Werner states.

  4. Simulation studies to evaluate the effect of fracture closure on the performance of naturally fractured reservoirs

    SciTech Connect

    Dauben, D.L.

    1991-07-15

    The study has two principal objectives: (1) To evaluate the effects of fracture closure on the recovery of oil and gas reserves from naturally fractured petroleum or natural gas reservoirs. (2) To evaluate procedures for improving the recovery of these reserves using innovative fluid injection techniques to maintain reservoir pressure and mitigate the impact of fracture closure. The total scope of the study has been subdivided into three main tasks: (1) Baseline studies (non-pressure sensitive fractures); (2)studies with pressure sensitive fractures; and (3) innovative approaches for improving oil recovery.

  5. Reservoir Characterization and Flow Simulation for CO 2-EOR in the Tensleep Formation Using Discrete Fracture Networks, Teapot Dome, Wyoming

    NASA Astrophysics Data System (ADS)

    Kavousi Ghahfarokhi, Payam

    The Tensleep oil reservoir at Teapot Dome, Wyoming, USA, is a naturally fractured tight sandstone reservoir that has been considered for carbon-dioxide enhanced oil recovery (CO2-EOR) and sequestration. CO2-EOR analysis requires a thorough understanding of the Tensleep fracture network. Wireline image logs from the field suggest that the reservoir fracture network is dominated by early formed structural hinge oblique fractures with interconnectivity enhanced by hinge parallel and hinge perpendicular fracture sets. Available post stack 3D seismic data are used to generate a seismic fracture intensity attribute for the reservoir fracture network. The resulting seismic fracture intensity is qualitatively correlated to the field production history. Wells located on hinge-oblique discontinuities are more productive than other wells in the field. We use Oda's method to upscale the fracture permeabilities in the discrete fracture network for use in a dual porosity fluid flow simulator. We analytically show that Oda's method is sensitive to the grid orientation relative to fracture set strike. Results show that the calculated permeability tensors have maximum geometric mean for the non-zero permeability components (kxx,kyy,kzz,kxy) when the dominant fracture set cuts diagonally through the grid cell at 45° relative to the grid cell principal directions (i,j). The geometric mean of the permeability tensor components falls to a minimum when the dominant fracture set is parallel to either grid wall (i or j principal directions). The latter case has off-diagonal permeability terms close to zero. We oriented the Tensleep reservoir grid to N72°W to minimize the off-diagonal permeability terms. The seismic fracture intensity attribute is then used to generate a realization of the reservoir fracture network. Subsequently, fracture properties are upscaled to the reservoir grid scale for a fully compositional flow simulation. We implemented a PVT analysis using CO2 swelling test

  6. Coupling Hydraulic Fracturing Propagation and Gas Well Performance for Simulation of Production in Unconventional Shale Gas Reservoirs

    NASA Astrophysics Data System (ADS)

    Wang, C.; Winterfeld, P. H.; Wu, Y. S.; Wang, Y.; Chen, D.; Yin, C.; Pan, Z.

    2014-12-01

    Hydraulic fracturing combined with horizontal drilling has made it possible to economically produce natural gas from unconventional shale gas reservoirs. An efficient methodology for evaluating hydraulic fracturing operation parameters, such as fluid and proppant properties, injection rates, and wellhead pressure, is essential for the evaluation and efficient design of these processes. Traditional numerical evaluation and optimization approaches are usually based on simulated fracture properties such as the fracture area. In our opinion, a methodology based on simulated production data is better, because production is the goal of hydraulic fracturing and we can calibrate this approach with production data that is already known. This numerical methodology requires a fully-coupled hydraulic fracture propagation and multi-phase flow model. In this paper, we present a general fully-coupled numerical framework to simulate hydraulic fracturing and post-fracture gas well performance. This three-dimensional, multi-phase simulator focuses on: (1) fracture width increase and fracture propagation that occurs as slurry is injected into the fracture, (2) erosion caused by fracture fluids and leakoff, (3) proppant subsidence and flowback, and (4) multi-phase fluid flow through various-scaled anisotropic natural and man-made fractures. Mathematical and numerical details on how to fully couple the fracture propagation and fluid flow parts are discussed. Hydraulic fracturing and production operation parameters, and properties of the reservoir, fluids, and proppants, are taken into account. The well may be horizontal, vertical, or deviated, as well as open-hole or cemented. The simulator is verified based on benchmarks from the literature and we show its application by simulating fracture network (hydraulic and natural fractures) propagation and production data history matching of a field in China. We also conduct a series of real-data modeling studies with different combinations of

  7. Terahertz-dependent identification of simulated hole shapes in oil-gas reservoirs

    NASA Astrophysics Data System (ADS)

    Bao, Ri-Ma; Zhan, Hong-Lei; Miao, Xin-Yang; Zhao, Kun; Feng, Cheng-Jing; Dong, Chen; Li, Yi-Zhang; Xiao, Li-Zhi

    2016-10-01

    Detecting holes in oil-gas reservoirs is vital to the evaluation of reservoir potential. The main objective of this study is to demonstrate the feasibility of identifying general micro-hole shapes, including triangular, circular, and square shapes, in oil-gas reservoirs by adopting terahertz time-domain spectroscopy (THz-TDS). We evaluate the THz absorption responses of punched silicon (Si) wafers having micro-holes with sizes of 20 μm-500 μm. Principal component analysis (PCA) is used to establish a model between THz absorbance and hole shapes. The positions of samples in three-dimensional spaces for three principal components are used to determine the differences among diverse hole shapes and the homogeneity of similar shapes. In addition, a new Si wafer with the unknown hole shapes, including triangular, circular, and square, can be qualitatively identified by combining THz-TDS and PCA. Therefore, the combination of THz-TDS with mathematical statistical methods can serve as an effective approach to the rapid identification of micro-hole shapes in oil-gas reservoirs. Project supported by the National Natural Science Foundation of China (Grant No. 61405259), the National Basic Research Program of China (Grant No. 2014CB744302), and the Specially Founded Program on National Key Scientific Instruments and Equipment Development, China (Grant No. 2012YQ140005).

  8. Preliminary Three-Dimensional Simulation of Sediment and Cesium Transport in the Ogi Dam Reservoir using FLESCOT – Task 6, Subtask 2

    SciTech Connect

    Onishi, Yasuo; Kurikami, Hiroshi; Yokuda, Satoru T.

    2014-03-28

    After the accident at the Fukushima Daiichi Nuclear Power Plant in March 2011, the Japan Atomic Energy Agency and the Pacific Northwest National Laboratory initiated a collaborative project on environmental restoration. In October 2013, the collaborative team started a task of three-dimensional modeling of sediment and cesium transport in the Fukushima environment using the FLESCOT (Flow, Energy, Salinity, Sediment Contaminant Transport) code. As the first trial, we applied it to the Ogi Dam Reservoir that is one of the reservoirs in the Japan Atomic Energy Agency’s (JAEA’s) investigation project. Three simulation cases under the following different temperature conditions were studied: • incoming rivers and the Ogi Dam Reservoir have the same water temperature • incoming rivers have lower water temperature than that of the reservoir • incoming rivers have higher water temperature than that of the reservoir. The preliminary simulations suggest that seasonal temperature changes influence the sediment and cesium transport. The preliminary results showed the following: • Suspended sand, and cesium adsorbed by sand, coming into the reservoirs from upstream rivers is deposited near the reservoir entrance. • Suspended silt, and cesium adsorbed by silt, is deposited farther in the reservoir. • Suspended clay, and cesium adsorbed by clay, travels the farthest into the reservoir. With sufficient time, the dissolved cesium reaches the downstream end of the reservoir. This preliminary modeling also suggests the possibility of a suitable dam operation to control the cesium migration farther downstream from the dam. JAEA has been sampling in the Ogi Dam Reservoir, but these data were not yet available for the current model calibration and validation for this reservoir. Nonetheless these preliminary FLESCOT modeling results were qualitatively valid and confirmed the applicability of the FLESCOT code to the Ogi Dam Reservoir, and in general to other reservoirs in

  9. Low-Sulfate Seawater Injection into Oil Reservoir to Avoid Scaling Problem

    NASA Astrophysics Data System (ADS)

    Merdhah, Amer Badr Bin; Mohd Yassin, Abu Azam

    This study presents the results of laboratory experiments carried out to investigate the formation of calcium, strontium and barium sulfates from mixing Angsi seawater or low sulfate seawater with the following sulfate contents (75, 50, 25, 5 and 1%) and formation water contain high concentration of calcium, strontium and barium ions at various temperatures (40-90°C) and atmospheric pressure. The knowledge of solubility of common oil field scale formation and how their solubilities are affected by changes in salinity and temperatures is also studied. Results show a large of precipitation occurred in all jars containing seawater while the amount of precipitation decreased when the low sulfate seawater was used. At higher temperatures the mass of precipitation of CaSO4 and SrSO4 scales increases and the mass of precipitation of BaSO4 scale decreases since the solubilities of CaSO4 and SrSO4 scales decreases and the solubility of BaSO4 increases with increasing temperature. It can be concluded that even at sulfate content of 1% there may still be a scaling problem.

  10. A simulation research on evaluation of development in shale oil reservoirs by near-miscible CO2 flooding

    NASA Astrophysics Data System (ADS)

    Lai, Fengpeng; Li, Zhiping; Fu, Yingkun; Yang, Zhihao; Li, Hong

    2015-08-01

    Shale oil is a key resource that could mitigate the impending energy shortage in the future. Despite its abundance in China, studies on shale oil are still at the preliminary stage. Shale oil development through CO2 flooding has been successfully implemented in the United States. Therefore, the mechanics of CO2 flooding in shale oil reservoirs should be investigated. This study applies a simulation method to evaluate the development efficiency of CO2 flooding in shale oil reservoirs. Near-miscible CO2 flooding can effectively develop shale oil. After 20 years, recovery could improve by up to 9.56% as a result of depletion development under near-miscible CO2 flooding with 0.5% pore volume gas injection. Horizontal well injection is better than vertical well injection in terms of sweep efficiency and recovery. Cyclic gas injection is superior to continuous gas injection because the former reduces gas channelling. Thus, the use of horizontal wells with near-miscible cyclic gas injections has the potential to effectively develop shale oil reservoirs.

  11. Assessing Reservoir Depositional Environments to Develop and Quantify Improvements in CO2 Storage Efficiency. A Reservoir Simulation Approach

    SciTech Connect

    Okwen, Roland; Frailey, Scott; Leetaru, Hannes; Moulton, Sandy

    2014-09-30

    The storage potential and fluid movement within formations are dependent on the unique hydraulic characteristics of their respective depositional environments. Storage efficiency (E) quantifies the potential for storage in a geologic depositional environment and is used to assess basinal or regional CO2 storage resources. Current estimates of storage resources are calculated using common E ranges by lithology and not by depositional environment. The objectives of this project are to quantify E ranges and identify E enhancement strategies for different depositional environments via reservoir simulation studies. The depositional environments considered include deltaic, shelf clastic, shelf carbonate, fluvial deltaic, strandplain, reef, fluvial and alluvial, and turbidite. Strategies considered for enhancing E include CO2 injection via vertical, horizontal, and deviated wells, selective completions, water production, and multi-well injection. Conceptual geologic and geocellular models of the depositional environments were developed based on data from Illinois Basin oil fields and gas storage sites. The geologic and geocellular models were generalized for use in other US sedimentary basins. An important aspect of this work is the development of conceptual geologic and geocellular models that reflect the uniqueness of each depositional environment. Different injection well completions methods were simulated to investigate methods of enhancing E in the presence of geologic heterogeneity specific to a depositional environment. Modeling scenarios included horizontal wells (length, orientation, and inclination), selective and dynamic completions, water production, and multiwell injection. A Geologic Storage Efficiency Calculator (GSECalc) was developed to calculate E from reservoir simulation output. Estimated E values were normalized to diminish their dependency on fluid relative permeability. Classifying depositional environments according to

  12. Mathematical simulation of temperatures in deep impoundments: verification tests of the Water Resources Engineers, Inc. model - Horsetooth and Flaming Gorge Reservoirs

    USGS Publications Warehouse

    King, D.L.; Sartoris, Jim J.

    1973-01-01

    Successful use of predictive mathematical models requires verification of the accuracy of the models by applying them to existing situations where the prediction can be compared with reality. A Corps of Engineers' modification of a deep reservoir thermal stratification model developed by Water Resources Engineers, Inc., was applied to two existing Bureau of Reclamation reservoirs for verification. Diffusion coefficients used for the Corps' Detroit Reservoir were found to apply to Horsetooth Reservoir in Colorado, for which very food computer input data were available. The Detroit diffusion coefficients gave a reasonable simulation of Flaming Gorge Reservoir in Wyoming and Utah, which has very complex and variable physical characteristics and for which only average-quality computer input data were available.

  13. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Technical progress report, July 1, 1996--September 30, 1996

    SciTech Connect

    Allison, M.L.

    1996-10-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project.

  14. List-Based Simulated Annealing Algorithm for Traveling Salesman Problem

    PubMed Central

    Zhan, Shi-hua; Lin, Juan; Zhang, Ze-jun

    2016-01-01

    Simulated annealing (SA) algorithm is a popular intelligent optimization algorithm which has been successfully applied in many fields. Parameters' setting is a key factor for its performance, but it is also a tedious work. To simplify parameters setting, we present a list-based simulated annealing (LBSA) algorithm to solve traveling salesman problem (TSP). LBSA algorithm uses a novel list-based cooling schedule to control the decrease of temperature. Specifically, a list of temperatures is created first, and then the maximum temperature in list is used by Metropolis acceptance criterion to decide whether to accept a candidate solution. The temperature list is adapted iteratively according to the topology of the solution space of the problem. The effectiveness and the parameter sensitivity of the list-based cooling schedule are illustrated through benchmark TSP problems. The LBSA algorithm, whose performance is robust on a wide range of parameter values, shows competitive performance compared with some other state-of-the-art algorithms. PMID:27034650

  15. iTOUGH2-EOS1SC. Multiphase Reservoir Simulator for Water under Sub- and Supercritical Conditions. User's Guide

    SciTech Connect

    Magnusdottir, Lilja; Finsterle, Stefan

    2015-03-01

    Supercritical fluids exist near magmatic heat sources in geothermal reservoirs, and the high enthalpy fluid is becoming more desirable for energy production with advancing technology. In geothermal modeling, the roots of the geothermal systems are normally avoided but in order to accurately predict the thermal behavior when wells are drilled close to magmatic intrusions, it is necessary to incorporate the heat sources into the modeling scheme. Modeling supercritical conditions poses a variety of challenges due to the large gradients in fluid properties near the critical zone. This work focused on using the iTOUGH2 simulator to model the extreme temperature and pressure conditions in magmatic geothermal systems.

  16. Toward optical signal processing using photonic reservoir computing.

    PubMed

    Vandoorne, Kristof; Dierckx, Wouter; Schrauwen, Benjamin; Verstraeten, David; Baets, Roel; Bienstman, Peter; Van Campenhout, Jan

    2008-07-21

    We propose photonic reservoir computing as a new approach to optical signal processing in the context of large scale pattern recognition problems. Photonic reservoir computing is a photonic implementation of the recently proposed reservoir computing concept, where the dynamics of a network of nonlinear elements are exploited to perform general signal processing tasks. In our proposed photonic implementation, we employ a network of coupled Semiconductor Optical Amplifiers (SOA) as the basic building blocks for the reservoir. Although they differ in many key respects from traditional software-based hyperbolic tangent reservoirs, we show using simulations that such a photonic reservoir can outperform traditional reservoirs on a benchmark classification task. Moreover, a photonic implementation offers the promise of massively parallel information processing with low power and high speed.

  17. Numerical simulation of the blast impact problem using the Direct Simulation Monte Carlo (DSMC) method

    NASA Astrophysics Data System (ADS)

    Sharma, Anupam; Long, Lyle N.

    2004-10-01

    A particle approach using the Direct Simulation Monte Carlo (DSMC) method is used to solve the problem of blast impact with structures. A novel approach to model the solid boundary condition for particle methods is presented. The solver is validated against an analytical solution of the Riemann shocktube problem and against experiments on interaction of a planar shock with a square cavity. Blast impact simulations are performed for two model shapes, a box and an I-shaped beam, assuming that the solid body does not deform. The solver uses domain decomposition technique to run in parallel. The parallel performance of the solver on two Beowulf clusters is also presented.

  18. Geology and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Annual report, October 1, 1996--September 30, 1997

    SciTech Connect

    Chidsey, T.C. Jr.; Anderson, P.B.; Morris, T.H.; Dewey, J.A. Jr.; Mattson, A.; Foster, C.B.; Snelgrove, S.H.; Ryer, T.A.

    1998-05-01

    The objective of the Ferron Sandstone (Utah) project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Both new and existing data is being integrated into a 3-D model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. The project is divided into four tasks: (1) regional stratigraphic analysis, (2) case studies, (3) reservoirs models, and (4) field-scale evaluation of exploration strategies. The primary objective of the regional stratigraphic analysis is to provide a more detailed interpretation of the stratigraphy and gross reservoir characteristics of the Ferron Sandstone as exposed in outcrop. The primary objective of the case-studies work is to develop a detailed geological and petrophysical characterization, at well-sweep scale or smaller, of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir. Work on tasks 3 and 4 consisted of developing two- and three-dimensional reservoir models at various scales. The bulk of the work on these tasks is being completed primarily during the last year of the project, and is incorporating the data and results of the regional stratigraphic analysis and case-studies tasks.

  19. Improved recovery from Gulf of Mexico reservoirs. Volume III (of 4): Characterization and simulation of representative resources. Final report, February 14, 1995--October 13, 1996

    SciTech Connect

    Kimbrell, W.C.; Bassiouni, Z.A.; Bourgoyne, A.T.

    1997-01-13

    Significant innovations have been made in seismic processing and reservoir simulation. In addition, significant advances have been made in deviated and horizontal drilling technologies. Effective application of these technologies along with improved integrated resource management methods offer opportunities to significantly increase Gulf of Mexico production, delay platform abandonments, and preserve access to a substantial remaining oil target for both exploratory drilling and advanced recovery processes. In an effort to illustrate the impact that these new technologies and sources of information can have upon the estimates of recoverable oil in the Gulf of Mexico, additional and detailed data was collected for two previously studied reservoirs: a South March Island reservoir operated by Taylor Energy and Gulf of Mexico reservoir operated by Mobil, whose exact location has been blind-coded at their request, and an additional third representative reservoir in the Gulf of Mexico, the KEKF-1 reservoir in West Delta Block 84 Field. The new data includes reprocessed 2-D seismic data, newly acquired 3-D data, fluid data, fluid samples, pressure data, well test data, well logs, and core data/samples. The new data was used to refine reservoir and geologic characterization of these reservoirs. Further laboratory investigation also provided additional simulation input data in the form of PVT properties, relative permeabilities, capillary pressures, and water compatibility. Geologic investigations were also conducted to refine the models of mud-rich submarine fan architectures used by seismic analysts and reservoir engineers. These results were also used, in part, to assist in the recharacterization of these reservoirs.

  20. Variable neighbourhood simulated annealing algorithm for capacitated vehicle routing problems

    NASA Astrophysics Data System (ADS)

    Xiao, Yiyong; Zhao, Qiuhong; Kaku, Ikou; Mladenovic, Nenad

    2014-04-01

    This article presents the variable neighbourhood simulated annealing (VNSA) algorithm, a variant of the variable neighbourhood search (VNS) combined with simulated annealing (SA), for efficiently solving capacitated vehicle routing problems (CVRPs). In the new algorithm, the deterministic 'Move or not' criterion of the original VNS algorithm regarding the incumbent replacement is replaced by an SA probability, and the neighbourhood shifting of the original VNS (from near to far by k← k+1) is replaced by a neighbourhood shaking procedure following a specified rule. The geographical neighbourhood structure is introduced in constructing the neighbourhood structures for the CVRP of the string model. The proposed algorithm is tested against 39 well-known benchmark CVRP instances of different scales (small/middle, large, very large). The results show that the VNSA algorithm outperforms most existing algorithms in terms of computational effectiveness and efficiency, showing good performance in solving large and very large CVRPs.

  1. Combined simulated annealing algorithm for the discrete facility location problem.

    PubMed

    Qin, Jin; Ni, Ling-Lin; Shi, Feng

    2012-01-01

    The combined simulated annealing (CSA) algorithm was developed for the discrete facility location problem (DFLP) in the paper. The method is a two-layer algorithm, in which the external subalgorithm optimizes the decision of the facility location decision while the internal subalgorithm optimizes the decision of the allocation of customer's demand under the determined location decision. The performance of the CSA is tested by 30 instances with different sizes. The computational results show that CSA works much better than the previous algorithm on DFLP and offers a new reasonable alternative solution method to it.

  2. Forward-Inverse Adaptive Techniques for Reservoir Characterization and Simulation: Theory and Applications

    SciTech Connect

    Doss, S D; Ezzedine, S; Gelinas, R; Chawathe, A

    2001-06-11

    A novel approach called Forward-Inverse Adaptive Techniques (FIAT) for reservoir characterization is developed and applied to three representative exploration cases. Inverse modeling refers to the determination of the entire reservoir permeability under steady state single-phase flow regime, given only field permeability, pressure and production well measurements. FIAT solves the forward and inverse partial differential equations (PDEs) simultaneously by adding a regularization term and filtering pressure gradients. An implicit adaptive-grid, Galerkin, numerical scheme is used to numerically solve the set of PDEs subject to pressure and permeability boundary conditions. Three examples are presented. Results from all three cases demonstrate attainable and reasonably accurate solutions and, more importantly, provide insights into the consequences of data undersampling.

  3. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Technical progress report, April 1--June 30, 1995

    SciTech Connect

    Allison, M.L.

    1995-07-28

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Technical progress this quarter is divided into regional stratigraphy, case studies, stochastic modeling and fluid-flow simulation, and technology transfer activities. The regional stratigraphy of the Ferron Sandstone outcrop belt from Last Chance Creek to Ferron Creek is being described and interpreted. Photomosaics and a database of existing surface and subsurface data are being used to determine the extent and depositional environment of each parasequence, and the nature of the contacts with adjacent rocks or flow units. For the second field season, detailed geological and petrophysical characterization of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir, is continuing at selected case-study areas.

  4. Control of Microbial Sulfide Production with Biocides and Nitrate in Oil Reservoir Simulating Bioreactors.

    PubMed

    Xue, Yuan; Voordouw, Gerrit

    2015-01-01

    Oil reservoir souring by the microbial reduction of sulfate to sulfide is unwanted, because it enhances corrosion of metal infrastructure used for oil production and processing. Reservoir souring can be prevented or remediated by the injection of nitrate or biocides, although injection of biocides into reservoirs is not commonly done. Whether combined application of these agents may give synergistic reservoir souring control is unknown. In order to address this we have used up-flow sand-packed bioreactors injected with 2 mM sulfate and volatile fatty acids (VFA, 3 mM each of acetate, propionate and butyrate) at a flow rate of 3 or 6 pore volumes (PV) per day. Pulsed injection of the biocides glutaraldehyde (Glut), benzalkonium chloride (BAC) and cocodiamine was used to control souring. Souring control was determined as the recovery time (RT) needed to re-establish an aqueous sulfide concentration of 0.8-1 mM (of the 1.7-2 mM before the pulse). Pulses were either for a long time (120 h) at low concentration (long-low) or for a short time (1 h) at high concentration (short-high). The short-high strategy gave better souring control with Glut, whereas the long-low strategy was better with cocodiamine. Continuous injection of 2 mM nitrate alone was not effective, because 3 mM VFA can fully reduce both 2 mM nitrate to nitrite and N2 and, subsequently, 2 mM sulfate to sulfide. No synergy was observed for short-high pulsed biocides and continuously injected nitrate. However, use of continuous nitrate and long-low pulsed biocide gave synergistic souring control with BAC and Glut, as indicated by increased RTs in the presence, as compared to the absence of nitrate. Increased production of nitrite, which increases the effectiveness of souring control by biocides, is the most likely cause for this synergy.

  5. Control of Microbial Sulfide Production with Biocides and Nitrate in Oil Reservoir Simulating Bioreactors

    PubMed Central

    Xue, Yuan; Voordouw, Gerrit

    2015-01-01

    Oil reservoir souring by the microbial reduction of sulfate to sulfide is unwanted, because it enhances corrosion of metal infrastructure used for oil production and processing. Reservoir souring can be prevented or remediated by the injection of nitrate or biocides, although injection of biocides into reservoirs is not commonly done. Whether combined application of these agents may give synergistic reservoir souring control is unknown. In order to address this we have used up-flow sand-packed bioreactors injected with 2 mM sulfate and volatile fatty acids (VFA, 3 mM each of acetate, propionate and butyrate) at a flow rate of 3 or 6 pore volumes (PV) per day. Pulsed injection of the biocides glutaraldehyde (Glut), benzalkonium chloride (BAC) and cocodiamine was used to control souring. Souring control was determined as the recovery time (RT) needed to re-establish an aqueous sulfide concentration of 0.8–1 mM (of the 1.7–2 mM before the pulse). Pulses were either for a long time (120 h) at low concentration (long-low) or for a short time (1 h) at high concentration (short-high). The short-high strategy gave better souring control with Glut, whereas the long-low strategy was better with cocodiamine. Continuous injection of 2 mM nitrate alone was not effective, because 3 mM VFA can fully reduce both 2 mM nitrate to nitrite and N2 and, subsequently, 2 mM sulfate to sulfide. No synergy was observed for short-high pulsed biocides and continuously injected nitrate. However, use of continuous nitrate and long-low pulsed biocide gave synergistic souring control with BAC and Glut, as indicated by increased RTs in the presence, as compared to the absence of nitrate. Increased production of nitrite, which increases the effectiveness of souring control by biocides, is the most likely cause for this synergy. PMID:26696994

  6. A new method for representing multiple wells with arbitrary rates in numerical reservoir simulation

    SciTech Connect

    Peaceman, D.W.

    1995-12-31

    A new equation is presented for calculating the equivalent wellblock radii for all N{sub w} wells in a reservoir. Arbitrary well rates and the interaction between wells are fully accounted for. The data required for the new equation may be obtained in a preprocessor by calculating N{sub w} single-phase pressure distributions. Then an accurate equivalent wellblock radius can be calculated for each well each time step, even under conditions where well rates vary with time.

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

    SciTech Connect

    Dutton, Shirley P.; Flanders, William A.

    2001-11-04

    The objective of this Class III project was demonstrate that reservoir characterization and enhanced oil recovery (EOR) by CO2 flood can increase production from slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico. Phase 1 of the project, reservoir characterization, focused on Geraldine Ford and East Ford fields, which are Delaware Mountain Group fields that produce from the upper Bell Canyon Formation (Ramsey sandstone). The demonstration phase of the project was a CO2 flood conducted in East Ford field, which is operated by Orla Petco, Inc., as the East Ford unit.

  8. Efficient and robust compositional two-phase reservoir simulation in fractured media

    NASA Astrophysics Data System (ADS)

    Zidane, A.; Firoozabadi, A.

    2015-12-01

    Compositional and compressible two-phase flow in fractured media has wide applications including CO2 injection. Accurate simulations are currently based on the discrete fracture approach using the cross-flow equilibrium model. In this approach the fractures and a small part of the matrix blocks are combined to form a grid cell. The major drawback is low computational efficiency. In this work we use the discrete-fracture approach to model the fractures where the fracture entities are described explicitly in the computational domain. We use the concept of cross-flow equilibrium in the fractures (FCFE). This allows using large matrix elements in the neighborhood of the fractures. We solve the fracture transport equations implicitly to overcome the Courant-Freidricks-Levy (CFL) condition in the small fracture elements. Our implicit approach is based on calculation of the derivative of the molar concentration of component i in phase (cαi ) with respect to the total molar concentration (ci ) at constant volume V and temperature T. This contributes to significant speed up of the code. The hybrid mixed finite element method (MFE) is used to solve for the velocity in both the matrix and the fractures coupled with the discontinuous Galerkin (DG) method to solve the species transport equations in the matrix, and a finite volume (FV) discretization in the fractures. In large scale problems the proposed approach is orders of magnitude faster than the existing models.

  9. Direct simulation of groundwater transit-time distributions using the reservoir theory

    NASA Astrophysics Data System (ADS)

    Etcheverry, David; Perrochet, Pierre

    Groundwater transit times are of interest for the management of water resources, assessment of pollution from non-point sources, and quantitative dating of groundwaters by the use of environmental isotopes. The age of water is the time water has spent in an aquifer since it has entered the system, whereas the transit time is the age of water as it exits the system. Water at the outlet of an aquifer is a mixture of water elements with different transit times, as a consequence of the different flow-line lengths. In this paper, transit-time distributions are calculated by coupling two existing methods, the reservoir theory and a recent age-simulation method. Based on the derivation of the cumulative age distribution over the whole domain, the approach accounts for the whole hydrogeological framework. The method is tested using an analytical example and its applicability illustrated for a regional layered aquifer. Results show the asymmetry and multimodality of the transit-time distribution even in advection-only conditions, due to the aquifer geometry and to the velocity-field heterogeneity. Résumé Les temps de transit des eaux souterraines sont intéressants à connaître pour gérer l'évaluation des ressources en eau dans le cas de pollution à partir de sources non ponctuelles, et aussi pour dater quantitativement les eaux souterraines au moyen des isotopes du milieu. L'âge de l'eau est le temps qu'elle a passé dans un aquifère depuis qu'elle est entrée dans le système, alors que le temps de transit est l'âge de l'eau au moment où elle quitte le système. L'eau à la sortie d'un aquifère est un mélange d'eaux possédant différents temps de transit, du fait des longueurs différentes des lignes de courant suivies. Dans ce papier, les distributions des temps de transit sont calculées en couplant deux méthodes, la théorie du réservoir et une méthode récente de simulation des âges. Basée sur la dérivation de la distribution cumulées des âges sur

  10. Design and Performance Frameworks for Constructing Problem-Solving Simulations

    PubMed Central

    Stevens, Ron; Palacio-Cayetano, Joycelin

    2003-01-01

    Rapid advancements in hardware, software, and connectivity are helping to shorten the times needed to develop computer simulations for science education. These advancements, however, have not been accompanied by corresponding theories of how best to design and use these technologies for teaching, learning, and testing. Such design frameworks ideally would be guided less by the strengths/limitations of the presentation media and more by cognitive analyses detailing the goals of the tasks, the needs and abilities of students, and the resulting decision outcomes needed by different audiences. This article describes a problem-solving environment and associated theoretical framework for investigating how students select and use strategies as they solve complex science problems. A framework is first described for designing on-line problem spaces that highlights issues of content, scale, cognitive complexity, and constraints. While this framework was originally designed for medical education, it has proven robust and has been successfully applied to learning environments from elementary school through medical school. Next, a similar framework is detailed for collecting student performance and progress data that can provide evidence of students' strategic thinking and that could potentially be used to accelerate student progress. Finally, experimental validation data are presented that link strategy selection and use with other metrics of scientific reasoning and student achievement. PMID:14506505

  11. Simulation of Detonation Problems with MLS Grid Free Methodology

    SciTech Connect

    Yao, J; Gunger, M E; Matuska, D A

    2002-06-05

    The MLS grid free rezone method, a simple, flexible finite difference method to solve general mechanics problems, especially detonation problems, is proposed in this paper. The spatial points that carry time dependent data are distributed in space in such a way that provides nearly uniform spacing of points, accurate presentation of boundaries, easy variation of resolutions and arbitrary deletion of irrelevant regions. Local finite difference operators are obtained with simple MLS differentiation. There is no specific topological or geometrical restriction with the distribution of data points. Therefore this method avoids many drawbacks of the traditional CFD methods. Because of its flexibility, it can be used to simulate a wide range of mechanics problems. Because of its simplicity, it has the potential to become a preferred method. Most traditional CFD methods, from a SPH view, can be considered as special cases of grid free methods of specific kernel functions. Such a generalization allows the development of a unified grid free CFD code that can be switched to various CFD methods by switching the kernel functions. Because of the flexibility in management and simplicity of coding, such a unified code is desired.

  12. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Annual report, October 1, 1995--September 30, 1996

    SciTech Connect

    Chidsey, T.C. Jr.

    1997-05-01

    The objective of the Ferron Sandstone project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir to allow realistic inter-well and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah was collected. Both new and existing data is being integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. This report covers research activities for fiscal year 1995-96, the third year of the project. Most work consisted of interpreting the large quantity of data collected over two field seasons. The project is divided into four tasks: (1) regional stratigraphic analysis, (2) case studies, (3) reservoirs models, and (4) field-scale evaluation of exploration strategies. The primary objective of the regional stratigraphic analysis is to provide a more detailed interpretation of the stratigraphy and gross reservoir characteristics of the Ferron Sandstone as exposed in outcrop. The primary objective of the case-studies work is to develop a detailed geological and petrophysical characterization, at well-sweep scale or smaller, of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir.

  13. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly progress report, July 1--September 30, 1995

    SciTech Connect

    Allison, M.L.

    1995-10-30

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. Technical progress this quarter is divided into regional stratigraphy, case studies, stochastic modeling and fluid-flow simulation, and technology transfer activities. The regional stratigraphy of the Ferron Sandstone outcrop belt is being described and interpreted. Detailed geological and petrophysical characterization of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir, is continuing at selected case-study areas. Interpretations of lithofacies, bounding surfaces, and other geologic information are being combined with permeability measurements from closely spaced traverses and from drill-hole cores (existing and two drilled during the quarter). Petrophysical and statistical analyses are being incorporated with the geological characterization to develop a three-dimensional model of the reservoirs through fluid-flow simulation.

  14. Petroleum and aqueous inclusions from deeply buried reservoirs: Experimental simulations and consequences for overpressure estimates

    NASA Astrophysics Data System (ADS)

    Pironon, Jacques; Bourdet, Julien

    2008-10-01

    Synthetic hydrocarbon and aqueous inclusions have been created in the laboratory batch reactors in order to mimic inclusion formation or re-equilibration in deeply buried reservoirs. Inclusions were synthesized in quartz and calcite using pure water and Mexican dead oil, or n-tetradecane (C 14H 30), at a temperature and pressure of 150 °C and 1 kbar. One-phase hydrocarbon inclusions are frequently observed at standard laboratory conditions leading to homogenization temperatures between 0 and 60 °C. UV epifluorescence of Mexican oil inclusions is not uniform; blue and green-yellow colored inclusions coexist; however, no clear evidence of variations in fluid chemistry were observed. Homogenization temperatures were recorded and the maxima of Th plotted on histograms are in good agreement with expected Th in a range of 6 °C. Broad histograms were reconstructed showing non-symmetrical Th distributions over a 20 °C temperature range centered on the expected Th. This histogram broadening is due to the fragility of the fluid inclusions that were created by re-filling of pre-existing microcavities. Such Th histograms are similar to Th histograms recorded on natural samples from deeply buried carbonate reservoirs. Th values lower than those expected were measured for hydrocarbon inclusions in quartz and calcite, and for aqueous inclusions in calcite. However, the results confirm the ability of fluid inclusions containing two immiscible fluids to lead to PT reconstructions, even in overpressured environments.

  15. Stress field respond to massive injection of cold water into a geothermal reservoir study by geomechanical simulation

    NASA Astrophysics Data System (ADS)

    Jeanne, P.; Rutqvist, J.

    2015-12-01

    In this paper, we study the evolution and distribution of the stress tensor within the northwest part of The Geysers geothermal field during 9 years of injection (from 2003 to 2012). Based on a refined 3D structural model, developed by Calpine Corporation, where the horizon surfaces are mapped, we use the GMS™ GUI to construct a realistic three-dimensional geologic model of the Northwest Geysers geothermal field. This model includes a low permeability graywacke layer that forms the caprock for the reservoir, an isothermal steam zone (the Normal Temperature Reservoir) within metagraywacke, a hornfels zone (the High Temperature Reservoir), and a felsite layer that is assumed to extend downward to the magmatic heat source. This model is mapped into a rectangular grid for use with the TOUGH-FLAC numerical simulator. Then, we reproduce the injection history of seven active wells between 2003 and 2012. Finally, our results are compared with previous works where the stress tensor was studied from the inversion of focal plane mechanism in the same area and during the same period. As in these publications we find that: (1) changes in the orientation of principal horizontal stress are very small after one decade of injection, and (2) at injection depth significant rotations of the initially vertically oriented maximum compressive principal stress occur in response to changes in the fluid injection rates. As observed in the field, we found that σ1 tilted towards the σ2 direction by approximately 15° when injection rates were at their peak level. Such a rotation consequently results in a local change in the state stress from a normal stress regime (Sv > SHmax> > Shmin) to a strike slip regime (SHmax> Sv > > Shmin) above and below the injection zone. Our results show that thermal processes are the principal cause for the stress tensor rotation.

  16. The use of detailed reservoir description and simulation studies in investigating completion strategies, cormorant, UK North Sea

    SciTech Connect

    Stiles, J.H.; Valenti, N.P.

    1987-01-01

    A portion of the Cormorant field in the U.K. North Sea is being developed using a subsea production system. All layers in the stratified reservoir section are being waterflooded concurrently by perforating the entire interval in both producers and injectors. The permeability contrast among the layers is such that there is potential for severe imbalance in the movement of the waterflood fronts, resulting in large volumes of early water production from high permeability layers and incomplete displacement of oil from less permeable layers. With the high cost of expanding platform facilities or performing workovers on subsea wells to re-distribute production and/or injection, there is considerable incentive to optimise the completions in new wells. This paper describes studies undertaken by Esso Exploration and Production U.K. to evaluate various completion strategies for newe subsea wells. These studies were done to complement work done by the operator, Shell U.K. Explorations and Production. The studies included detailed reservoir description work to define the oil-in-pace and permeability distribution, followed by simulation of the waterflood for a representative reservoir cross-section. Wellbore, flowline and pipeline hydraulics for the complex productions and injection system were included to more accurately model well rates. The results provide general insight into the nature of the displacement when waterflooding a stratified section with a limited nuber of wells. They also provide specific guidance on: (1) dual vs. single completions, (2) perforating, testing and stimulation sequence and (3) the benefits of partially perforating high permeability sands.

  17. Sensitivity Studies of 3D Geothermal Reservoir Simulation: A Case Study in I-Lan Plain, Taiwan

    NASA Astrophysics Data System (ADS)

    Kuo, C. W.; Song, S. R.

    2015-12-01

    A large scale geothermal project conducted by Ministry of Science and Technology is initiated recently in I-Lan south area, northeastern Taiwan. The ultimate goal of this national project is to increase the percentage of renewable energy (ex. geothermal energy) to generate electricity. An integrated team which consists of various specialties are held together to investigate I-Lan area comprehensively. For example, I-Lan geological data, petrophysical analysis, seismicity, temperature gradient and distribution, hydrology, geochemistry, and heat source study etc. The geothermal gradient measured at one drilling well (1200m deep) is up to 50˚C/km and the prediction of temperature based on fluid inclusion analysis could be up to 300˚C. The geothermal reservoir is expected to occur at a fractured geological formation, Siling sandstone layer. A 3D subsurface geological model is built mainly based on the seismic exploration of the subsurface structure and well log data. According to the current conceptual model, the target area is bounded by two main faults, Jiaosi and Choshui faults. The preliminary results from all the investigations are integrated and used as input parameters to create a realistic numerical reservoir model. Numerical simulator TOUGH2 is used to study the geothermal energy potential. The initial state of temperature distribution is simulated and compared to the high resolution of magnetotelluric (MT) data. Simulation results show that they have similar pattern and therefore the prediction of geothermal potential in this area would be more reliable. Based on the realistic initial state, sensitivity studies are performed to investigate effects of relevant parameters on temperature distribution.

  18. The self-similar solutions of the problem of carbon dioxide injection into the reservoir saturated with methane and its hydrate

    NASA Astrophysics Data System (ADS)

    Musakaev, N. G.; Khasanov, M. K.

    2016-10-01

    In this paper the research of carbon dioxide injection into a porous medium initially saturated with methane and its hydrate was performed. The mathematical model of heat and mass transfer in a porous media, accompanied by the formation of carbon dioxide hydrate, is presented. The self-similar solutions, for the axisymmetric problem definition, were built. These solutions describe the distribution of the fluid parameters in a reservoir.

  19. Geological and petrophysical characterization of the ferron sandstone for 3-D simulation of a fluvial-deltaic reservoir. Annual report, October 1, 1994--September 30, 1995

    SciTech Connect

    Chidsey, T.C. Jr.; Allison, M.L.

    1996-05-01

    The objective of the Ferron Sandstone project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah was collected. Both new and existing data is being integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. This report covers research activities for fiscal year 1994-95, the second year of the project. Most work consisted of developing field methods and collecting large quantities of existing and new data. We also continued to develop preliminary regional and case-study area interpretations. The project is divided into four tasks: (1) regional stratigraphic analysis, (2) case studies, (3) reservoirs models, and (4) field-scale evaluation of exploration strategies.

  20. 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

    Dutton, S.P.; Flanders, W.A.; Guzman, J.I.; Zirczy, H.

    1999-06-08

    The objective of this Class III project is to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost-effective way to recover a higher percentage of the original oil in place through geologically based field development. This year the project focused on reservoir characterization of the East Ford unit, a representative Delaware Mountain Group field that produces from the upper Bell Canyon Formation (Ramsey Sandstone). The field, discovered in 1960, is operated by Orla Petco, Inc., as the East Ford unit; it contained an estimated 19.8 million barrels (MMbbl) of original oil in place. Petrophysical characterization of the East Ford unit was accomplished by integrating core and log data and quantifying petrophysical properties from wireline logs. Most methods of petrophysical analysis that had been developed during an earlier study of the Ford Geraldine unit were successfully transferred to the East Ford unit. The approach that was used to interpret water saturation from resistivity logs, however, had to be modified because in some East Ford wells the log-calculated water saturation was too high and inconsistent with observations made during the actual production. Log-porosity to core-porosity transforms and core-porosity to core-permeability transforms were derived from the East Ford reservoir. The petrophysical data were used to map porosity, permeability, net pay, water saturation, mobil-oil saturation, and other reservoir properties.

  1. Application of integrated reservoir management and reservoir characterization to optimize infill drilling. Annual technical progress report, June 13, 1996--June 12, 1997

    SciTech Connect

    Nevans, J.W.; Pregger, B.; Blasingame, T.; Doublet, L.; Freeman, G.; Callard, J.; Moore, D.; Davies, D.; Vessell, R.

    1997-08-01

    Infill drilling of wells on a uniform spacing, without regard to reservoir performance and characterization, does not optimize reservoir development because it fails to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, and carbonate reservoirs in particular. New and emerging technologies, such as geostatistical modeling, rigorous decline curve analysis, reservoir rock typing, and special core analysis can be used to develop a 3-D simulation model for prediction of infill locations. The purpose of this project is to demonstrate the application of advanced secondary recovery technologies to remedy producibility problems in typical shallow shelf carbonate reservoirs of the Permian Basin, Texas. Typical problems include poor sweep efficiency, poor balancing of injection and production rates, and completion techniques that are inadequate for optimal production and injection.

  2. Numerical simulation of phase transition problems with explicit interface tracking

    SciTech Connect

    Hu, Yijing; Shi, Qiangqiang; de Almeida, Valmor F.; Li, Xiao-lin

    2015-12-19

    Phase change is ubiquitous in nature and industrial processes. Started from the Stefan problem, it is a topic with a long history in applied mathematics and sciences and continues to generate outstanding mathematical problems. For instance, the explicit tracking of the Gibbs dividing surface between phases is still a grand challenge. Our work has been motivated by such challenge and here we report on progress made in solving the governing equations of continuum transport in the presence of a moving interface by the front tracking method. The most pressing issue is the accounting of topological changes suffered by the interface between phases wherein break up and/or merge takes place. The underlying physics of topological changes require the incorporation of space-time subscales not at reach at the moment. Therefore we use heuristic geometrical arguments to reconnect phases in space. This heuristic approach provides new insight in various applications and it is extensible to include subscale physics and chemistry in the future. We demonstrate the method on applications such as simulating freezing, melting, dissolution, and precipitation. The later examples also include the coupling of the phase transition solution with the Navier-Stokes equations for the effect of flow convection.

  3. Numerical simulation of phase transition problems with explicit interface tracking

    DOE PAGES

    Hu, Yijing; Shi, Qiangqiang; de Almeida, Valmor F.; ...

    2015-12-19

    Phase change is ubiquitous in nature and industrial processes. Started from the Stefan problem, it is a topic with a long history in applied mathematics and sciences and continues to generate outstanding mathematical problems. For instance, the explicit tracking of the Gibbs dividing surface between phases is still a grand challenge. Our work has been motivated by such challenge and here we report on progress made in solving the governing equations of continuum transport in the presence of a moving interface by the front tracking method. The most pressing issue is the accounting of topological changes suffered by the interfacemore » between phases wherein break up and/or merge takes place. The underlying physics of topological changes require the incorporation of space-time subscales not at reach at the moment. Therefore we use heuristic geometrical arguments to reconnect phases in space. This heuristic approach provides new insight in various applications and it is extensible to include subscale physics and chemistry in the future. We demonstrate the method on applications such as simulating freezing, melting, dissolution, and precipitation. The later examples also include the coupling of the phase transition solution with the Navier-Stokes equations for the effect of flow convection.« less

  4. Application of simulated annealing to some seismic problems

    NASA Astrophysics Data System (ADS)

    Velis, Danilo Ruben

    Wavelet estimation, ray tracing, and traveltime inversion are fundamental problems in seismic exploration. They can be finally reduced to minimizing a highly nonlinear cost function with respect to a certain set of unknown parameters. I use simulated annealing (SA) to avoid local minima and inaccurate solutions often arising by the use of linearizing methods. I illustrate all applications using numerical and/or real data examples. The first application concerns the 4th-order cumulant matching (CM) method for wavelet estimation. Here the reliability of the derived wavelets depends strongly on the amount of data. Tapering the trace cumulant estimate reduces significantly this dependency, and allows for a trace-by-trace implementation. For this purpose, a hybrid strategy that combines SA and gradient-based techniques provides efficiency and accuracy. In the second application I present SART (SA ray tracing), which is a novel method for solving the two-point ray tracing problem. SART overcomes some well known difficulties in standard methods, such as the selection of new take-off angles, and the multipathing problem. SA finds the take-off angles so that the total traveltime between the endpoints is a global minimum. SART is suitable for tracing direct, reflected, and headwaves, through complex 2-D and 3-D media. I also develop a versatile model representation in terms of a number of regions delimited by curved interfaces. Traveltime tomography is the third SA application. I parameterize the subsurface geology by using adaptive-grid bicubic B-splines for smooth models, or parametric 2-D functions for anomaly bodies. The second approach may find application in archaeological and other near-surface studies. The nonlinear inversion process attempts to minimize the rms error between observed and predicted traveltimes.

  5. Application of advanced reservoir characterization, simulation, and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, West Texas (Delaware Basin), Class III

    SciTech Connect

    Dutton, Shirley P.; Flanders, William A.; Zirczy, Helena H.

    2000-05-24

    The objective of this Class 3 project was to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. Phase 1 of the project, reservoir characterization, was completed this year, and Phase 2 began. The project is focused on East Ford field, a representative Delaware Mountain Group field that produces from the upper Bell Canyon Formation (Ramsey sandstone). The field, discovered in 1960, is operated by Oral Petco, Inc., as the East Ford unit. A CO{sub 2} flood is being conducted in the unit, and this flood is the Phase 2 demonstration for the project.

  6. Limitations in the use of pseudofunctions for up-scaling reservoir simulation models

    SciTech Connect

    Taggart, I.J.; Soedarmo, E.; Paterson, L.

    1995-12-31

    This work presents an alternative methodology of generating two-phase pseudo relative permeability and capillary pressure functions, using numerical simulation, when non-constant characteristic saturation curves exert a strong impact on the displacement process. The proposed length-dependence pseudofunction technique generates pseudofunctions from 2-dimensional cross-sectional black-oil simulations and later used in a 1-simulation predictions are compared to those of the conventional Kyte and Berry method. In addition to this, a case example is given to validate the application of length-dependent pseudos in a 3-dimensional simulation. In this example, sets of length-dependence pseudofunctions were generated and used in a 2-dimensional areal study. Simulation results showed that: (a) Curved saturation characteristic velocities occurred in most up-scaled representations and (b) The introduction of length-dependence pseudofunctions could result in improved predictions using coarse simulation models.

  7. Drainage-system development in consecutive melt seasons at a polythermal, Arctic glacier, evaluated by flow-recession analysis and linear-reservoir simulation.

    PubMed

    Hodgkins, Richard; Cooper, Richard; Tranter, Martyn; Wadham, Jemma

    2013-07-26

    [1] The drainage systems of polythermal glaciers play an important role in high-latitude hydrology, and are determinants of ice flow rate. Flow-recession analysis and linear-reservoir simulation of runoff time series are here used to evaluate seasonal and inter-annual variability in the drainage system of the polythermal Finsterwalderbreen, Svalbard, in 1999 and 2000. Linear-flow recessions are pervasive, with mean coefficients of a fast reservoir varying from 16 (1999) to 41 h (2000), and mean coefficients of an intermittent, slow reservoir varying from 54 (1999) to 114 h (2000). Drainage-system efficiency is greater overall in the first of the two seasons, the simplest explanation of which is more rapid depletion of the snow cover. Reservoir coefficients generally decline during each season (at 0.22 h d(-1) in 1999 and 0.52 h d(-1) in 2000), denoting an increase in drainage efficiency. However, coefficients do not exhibit a consistent relationship with discharge. Finsterwalderbreen therefore appears to behave as an intermediate case between temperate glaciers and other polythermal glaciers with smaller proportions of temperate ice. Linear-reservoir runoff simulations exhibit limited sensitivity to a relatively wide range of reservoir coefficients, although the use of fixed coefficients in a spatially lumped model can generate significant subseasonal error. At Finsterwalderbreen, an ice-marginal channel with the characteristics of a fast reservoir, and a subglacial upwelling with the characteristics of a slow reservoir, both route meltwater to the terminus. This suggests that drainage-system components of significantly contrasting efficiencies can coexist spatially and temporally at polythermal glaciers.

  8. Drainage-system development in consecutive melt seasons at a polythermal, Arctic glacier, evaluated by flow-recession analysis and linear-reservoir simulation

    PubMed Central

    Hodgkins, Richard; Cooper, Richard; Tranter, Martyn; Wadham, Jemma

    2013-01-01

    [1] The drainage systems of polythermal glaciers play an important role in high-latitude hydrology, and are determinants of ice flow rate. Flow-recession analysis and linear-reservoir simulation of runoff time series are here used to evaluate seasonal and inter-annual variability in the drainage system of the polythermal Finsterwalderbreen, Svalbard, in 1999 and 2000. Linear-flow recessions are pervasive, with mean coefficients of a fast reservoir varying from 16 (1999) to 41 h (2000), and mean coefficients of an intermittent, slow reservoir varying from 54 (1999) to 114 h (2000). Drainage-system efficiency is greater overall in the first of the two seasons, the simplest explanation of which is more rapid depletion of the snow cover. Reservoir coefficients generally decline during each season (at 0.22 h d−1 in 1999 and 0.52 h d−1 in 2000), denoting an increase in drainage efficiency. However, coefficients do not exhibit a consistent relationship with discharge. Finsterwalderbreen therefore appears to behave as an intermediate case between temperate glaciers and other polythermal glaciers with smaller proportions of temperate ice. Linear-reservoir runoff simulations exhibit limited sensitivity to a relatively wide range of reservoir coefficients, although the use of fixed coefficients in a spatially lumped model can generate significant subseasonal error. At Finsterwalderbreen, an ice-marginal channel with the characteristics of a fast reservoir, and a subglacial upwelling with the characteristics of a slow reservoir, both route meltwater to the terminus. This suggests that drainage-system components of significantly contrasting efficiencies can coexist spatially and temporally at polythermal glaciers. PMID:25598557

  9. Geological and petrophysical characterization of the ferron sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly report, January 1 - March 31, 1996

    SciTech Connect

    Allison, M.L.

    1996-04-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial- deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Technical progress this quarter is divided into case-study evaluation, geostatistics, and technology transfer activities. The work focused on one parasequence set, referred to as the Kf-1, in the Willow Springs Wash and Ivie Creek case-study areas. In the Ivie Creek case-study area the Kf-1 represents a river-dominated delta deposit which changes from proximal to distal from east to west. In the Willow Springs Wash case-study area the Kf-1 contains parasequences which represent river-dominated and wave-modified environments of deposition. Interpretations of lithofacies, bounding surfaces, and other geologic information are being used to determine reservoir architecture. Graphical interpretations of important flow boundaries in the case-study areas, identified on photomosaics, are being used to construct cross sections, paleogeographic, maps, and reservoir models. Geostatistical analyses are being incorporated with the geological characterization to develop a three-dimensional model of the reservoirs for fluid-flow simulation.

  10. Reservoir characterization of Pennsylvanian sandstone reservoirs. Final report

    SciTech Connect

    Kelkar, M.

    1995-02-01

    This final report summarizes the progress during the three years of a project on Reservoir Characterization of Pennsylvanian Sandstone Reservoirs. The report is divided into three sections: (i) reservoir description; (ii) scale-up procedures; (iii) outcrop investigation. The first section describes the methods by which a reservoir can be described in three dimensions. The next step in reservoir description is to scale up reservoir properties for flow simulation. The second section addresses the issue of scale-up of reservoir properties once the spatial descriptions of properties are created. The last section describes the investigation of an outcrop.

  11. Authors' reply to discussion of reservoir simulation: state of the art

    SciTech Connect

    Coats, K.H.

    1983-06-01

    This article argues that although many of the mechanisms operative in chemical flooding are not well understood, a final judgment of curently available simulators cannot be made until adequate laboratory data are available to exploit the mechansims that are known. Refers to the Bell Creek micellar/polymer pilot simulation and chemical flood simulation of the El Dorado pilot as compared to the field results.

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

    SciTech Connect

    Dutton, Shirley P.; Flanders, William A.; Mendez, Daniel L.

    2001-05-08

    The objective of this Class 3 project was demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstone's of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost effective way to recover oil more economically through geologically based field development. This project was focused on East Ford field, a Delaware Mountain Group field that produced from the upper Bell Canyon Formation (Ramsey sandstone). The field, discovered in 9160, is operated by Oral Petco, Inc., as the East Ford unit. A CO2 flood was being conducted in the unit, and this flood is the Phase 2 demonstration for the project.

  13. Simulation study to determine the feasibility of injecting hydrogen sulfide, carbon dioxide and nitrogen gas injection to improve gas and oil recovery oil-rim reservoir

    NASA Astrophysics Data System (ADS)

    Eid, Mohamed El Gohary

    This study is combining two important and complicated processes; Enhanced Oil Recovery, EOR, from the oil rim and Enhanced Gas Recovery, EGR from the gas cap using nonhydrocarbon injection gases. EOR is proven technology that is continuously evolving to meet increased demand and oil production and desire to augment oil reserves. On the other hand, the rapid growth of the industrial and urban development has generated an unprecedented power demand, particularly during summer months. The required gas supplies to meet this demand are being stretched. To free up gas supply, alternative injectants to hydrocarbon gas are being reviewed to support reservoir pressure and maximize oil and gas recovery in oil rim reservoirs. In this study, a multi layered heterogeneous gas reservoir with an oil rim was selected to identify the most optimized development plan for maximum oil and gas recovery. The integrated reservoir characterization model and the pertinent transformed reservoir simulation history matched model were quality assured and quality checked. The development scheme is identified, in which the pattern and completion of the wells are optimized to best adapt to the heterogeneity of the reservoir. Lateral and maximum block contact holes will be investigated. The non-hydrocarbon gases considered for this study are hydrogen sulphide, carbon dioxide and nitrogen, utilized to investigate miscible and immiscible EOR processes. In November 2010, re-vaporization study, was completed successfully, the first in the UAE, with an ultimate objective is to examine the gas and condensate production in gas reservoir using non hydrocarbon gases. Field development options and proces schemes as well as reservoir management and long term business plans including phases of implementation will be identified and assured. The development option that maximizes the ultimate recovery factor will be evaluated and selected. The study achieved satisfactory results in integrating gas and oil

  14. 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.

  15. Numerical simulations of blast-impact problems using the direct simulation Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Sharma, Anupam

    There is an increasing need to design protective structures that can withstand or mitigate the impulsive loading due to the impact of a blast or a shock wave. A preliminary step in designing such structures is the prediction of the pressure loading on the structure. This is called the "load definition." This thesis is focused on a numerical approach to predict the load definition on arbitrary geometries for a given strength of the incident blast/shock wave. A particle approach, namely the Direct Simulation Monte Carlo (DSMC) method, is used as the numerical model. A three-dimensional, time-accurate DSMC flow solver is developed as a part of this study. Embedded surfaces, modeled as triangulations, are used to represent arbitrary-shaped structures. Several techniques to improve the computational efficiency of the algorithm of particle-structure interaction are presented. The code is designed using the Object Oriented Programming (OOP) paradigm. Domain decomposition with message passing is used to solve large problems in parallel. The solver is extensively validated against analytical results and against experiments. Two kinds of geometries, a box and an I-shaped beam are investigated for blast impact. These simulations are performed in both two- and three-dimensions. A major portion of the thesis is dedicated to studying the uncoupled fluid dynamics problem where the structure is assumed to remain stationary and intact during the simulation. A coupled, fluid-structure dynamics problem is solved in one spatial dimension using a simple, spring-mass-damper system to model the dynamics of the structure. A parametric study, by varying the mass, spring constant, and the damping coefficient, to study their effect on the loading and the displacement of the structure is also performed. Finally, the parallel performance of the solver is reported for three sample-size problems on two Beowulf clusters.

  16. Numerical Simulation of Magma Reservoirs to Interpret Chrono-Chemical Signal

    NASA Astrophysics Data System (ADS)

    Lovera, O. M.; Harrison, M.; Schmitt, A. K.; Wielicki, M. M.; Tierney, C. R.

    2015-12-01

    We have developed a 2-D finite difference thermokinetic model to describe the evolution of open-system magma reservoirs incorporating crustal assimilation, melt recharge and fractional crystallization. The model is based on a T-crystallization relationship coupled to a zircon growth model calibrated from zircon solubility and a crustal T-assimilation curve from the EC-RAFC models of Spera and Bohrson (2004). Our model takes into account the latent heat of melting and/or solidification and features temperature-dependent thermal diffusivity. Trace element abundances in the melt are calculated through conservation of mass and isotopic speciation allowing prediction of the distribution of ɛHf values in zircons. Applications to model the evolution of deeply emplaced large granitoids (i.e., ~25km, ~15000 km3) show that steady recharge yields a zircon population that records the full spectrum of ɛHf in the system whereas no recharge yields a much narrower range. . Insights gained from modeling reinforce our view that the relationship between assimilation and geothermal structure can be used to estimate past crustal thickness of convergent margins. Modeling of shallow, initially small, subvolcanic magma reservoirs (i.e., ~7 km, ~200 km3) permits insights into zircon age and compositional variability for large silicic volcanic fields and associated calderas. Thermal modeling indicates that substantial recharge is required to maintain magmatic temperatures in the core of an intrusive complex where zircon remains saturated for periods of 100's of kiloyears. Coupled with previously developed statistical methods, zircon rim-ages predicted by the model were compared to the U-Th rim ages measured from five distinct lava domes of the Altiplano-Puna Volcanic Complex erupted between ca. 87 and 120 ka. The fitting constrains the amount of recharge to ~10-3 km3/a between the time of initial intrusion (>500 ka) and the eruption age (75-100 ka). Thus zircons may have the potential to

  17. Subglacial melting associated with activity at Bárdarbunga volcano, Iceland, explored using numerical reservoir simulations

    NASA Astrophysics Data System (ADS)

    Reynolds, Hannah I.; Gudmundsson, Magnús T.; Högnadóttir, Thórdís

    2015-04-01

    cause rapid increase in geothermal activity. However, a shallow intrusion into a cold groundwater reservoir will have a very muted thermal response even when an intrusion stops within a few tens of meters from the surface. Thus, our results indicate that minor subglacial eruptions, similar or slightly larger than the small eruption north of the glacier on the 29 August, are the most plausible explanation for the formation of the ice cauldrons observed. These results have implications for the understanding and interpretation of thermal signals observed at ice-covered volcanoes, highlighting the importance of reservoir/bedrock thermal state prior to intrusion.

  18. Numerical simulations of depressurization-induced gas production from gas hydrate reservoirs at the Walker Ridge 312 site, northern Gulf of Mexico

    SciTech Connect

    Myshakin, Evgeniy M.; Gaddipati, Manohar; Rose, Kelly; Anderson, Brian J.

    2012-06-01

    In 2009, the Gulf of Mexico (GOM) Gas Hydrates Joint-Industry-Project (JIP) Leg II drilling program confirmed that gas hydrate occurs at high saturations within reservoir-quality sands in the GOM. A comprehensive logging-while-drilling dataset was collected from seven wells at three sites, including two wells at the Walker Ridge 313 site. By constraining the saturations and thicknesses of hydrate-bearing sands using logging-while-drilling data, two-dimensional (2D), cylindrical, r-z and three-dimensional (3D) reservoir models were simulated. The gas hydrate occurrences inferred from seismic analysis are used to delineate the areal extent of the 3D reservoir models. Numerical simulations of gas production from the Walker Ridge reservoirs were conducted using the depressurization method at a constant bottomhole pressure. Results of these simulations indicate that these hydrate deposits are readily produced, owing to high intrinsic reservoir-quality and their proximity to the base of hydrate stability. The elevated in situ reservoir temperatures contribute to high (5–40 MMscf/day) predicted production rates. The production rates obtained from the 2D and 3D models are in close agreement. To evaluate the effect of spatial dimensions, the 2D reservoir domains were simulated at two outer radii. The results showed increased potential for formation of secondary hydrate and appearance of lag time for production rates as reservoir size increases. Similar phenomena were observed in the 3D reservoir models. The results also suggest that interbedded gas hydrate accumulations might be preferable targets for gas production in comparison with massive deposits. Hydrate in such accumulations can be readily dissociated due to heat supply from surrounding hydrate-free zones. Special cases were considered to evaluate the effect of overburden and underburden permeability on production. The obtained data show that production can be significantly degraded in comparison with a case using

  19. Petrophysical Characterization and Reservoir Simulator for Methane Gas Production from Gulf of Mexico Hydrates

    SciTech Connect

    Kishore Mohanty; Bill Cook; Mustafa Hakimuddin; Ramanan Pitchumani; Damiola Ogunlana; Jon Burger; John Shillinglaw

    2006-06-30

    Gas hydrates are crystalline, ice-like compounds of gas and water molecules that are formed under certain thermodynamic conditions. Hydrate deposits occur naturally within ocean sediments just below the sea floor at temperatures and pressures existing below about 500 meters water depth. Gas hydrate is also stable in conjunction with the permafrost in the Arctic. Most marine gas hydrate is formed of microbially generated gas. It binds huge amounts of methane into the sediments. Estimates of the amounts of methane sequestered in gas hydrates worldwide are speculative and range from about 100,000 to 270,000,000 trillion cubic feet (modified from Kvenvolden, 1993). Gas hydrate is one of the fossil fuel resources that is yet untapped, but may play a major role in meeting the energy challenge of this century. In this project novel techniques were developed to form and dissociate methane hydrates in porous media, to measure acoustic properties and CT properties during hydrate dissociation in the presence of a porous medium. Hydrate depressurization experiments in cores were simulated with the use of TOUGHFx/HYDRATE simulator. Input/output software was developed to simulate variable pressure boundary condition and improve the ease of use of the simulator. A series of simulations needed to be run to mimic the variable pressure condition at the production well. The experiments can be matched qualitatively by the hydrate simulator. The temperature of the core falls during hydrate dissociation; the temperature drop is higher if the fluid withdrawal rate is higher. The pressure and temperature gradients are small within the core. The sodium iodide concentration affects the dissociation pressure and rate. This procedure and data will be useful in designing future hydrate studies.

  20. Monte Carlo molecular simulation of the hydration of Na-montmorillonite at reservoir conditions.

    PubMed

    de Pablo, L; Chávez, M L; Sum, A K; de Pablo, J J

    2004-01-08

    The hydration of Na-saturated Wyoming-type montmorillonite is investigated by Monte Carlo simulations at constant stress in the NP(zz)T ensemble and at constant chemical potential in the microVT ensemble, at the sedimentary basin temperature of 353 K and pressure of 625 bar, equivalent to 2-4 km depth. The simulations use procedures established in Chavez-Paez et al. [J. Chem. Phys. 114, 1405 (2001)]. At these conditions, simulations predict a single stable form of 1,2-water layer Na-montmorillonite, containing 164.38 mg/g or 53.37 molecules/layer of adsorbed water and having a spacing of 12.72 A. The corresponding density is 0.32 g/ml. Sodium ions are coordinated with six molecules of water separated 2.30-2.33 A. Water molecules are closer to the central interlayer plane and the spacing is larger than that at 300 K and 1 bar. The interlayer configuration consists of two symmetrical layers of oriented water molecules 1.038 A from the central plane, with the hydrogen atoms in two outermost layers, 3.826 A apart, and the sodium ions on the central plane located between the water layers. The interlayer configuration can be considered to be a stable two-layer intermediate between the one- and two-layer hydrates. Our simulations do not predict formation of other hydrates of Na-montmorillonite at 353 K and 615 bar.

  1. Parallel reservoir computing using optical amplifiers.

    PubMed

    Vandoorne, Kristof; Dambre, Joni; Verstraeten, David; Schrauwen, Benjamin; Bienstman, Peter

    2011-09-01

    Reservoir computing (RC), a computational paradigm inspired on neural systems, has become increasingly popular in recent years for solving a variety of complex recognition and classification problems. Thus far, most implementations have been software-based, limiting their speed and power efficiency. Integrated photonics offers the potential for a fast, power efficient and massively parallel hardware implementation. We have previously proposed a network of coupled semiconductor optical amplifiers as an interesting test case for such a hardware implementation. In this paper, we investigate the important design parameters and the consequences of process variations through simulations. We use an isolated word recognition task with babble noise to evaluate the performance of the photonic reservoirs with respect to traditional software reservoir implementations, which are based on leaky hyperbolic tangent functions. Our results show that the use of coherent light in a well-tuned reservoir architecture offers significant performance benefits. The most important design parameters are the delay and the phase shift in the system's physical connections. With optimized values for these parameters, coherent semiconductor optical amplifier (SOA) reservoirs can achieve better results than traditional simulated reservoirs. We also show that process variations hardly degrade the performance, but amplifier noise can be detrimental. This effect must therefore be taken into account when designing SOA-based RC implementations.

  2. A Spreadsheet Simulation of the Monty Hall Problem

    ERIC Educational Resources Information Center

    Patterson, Mike C.; Harmel, Bob; Friesen, Dan

    2010-01-01

    The "Monty Hall" problem or "Three Door" problem--where a person chooses one of three doors in hope of winning a valuable prize but is subsequently offered the choice of changing his or her selection--is a well known and often discussed probability problem. In this paper, the structure, history, and ultimate solution of the…

  3. Simulation Modeling of Zooplankton and Benthos in Reservoirs: Documentation and Development of Model Constructs.

    DTIC Science & Technology

    1980-03-01

    phosphorus to account for material flow in the system. Fourth, the recommended minimum time frame for model simulation is 1 day. Subject areas covered by...percent N after 15 weeks in a buffered Hexamine solution (Hopkins 1968). Hopkins believed that most of the leached material was protein. Similar...Modeling such a simple flow of material would be relatively easy, but, unfortunately, it would probably have little relation to the real world. The

  4. Problem-Solving in the Pre-Clinical Curriculum: The Uses of Computer Simulations.

    ERIC Educational Resources Information Center

    Michael, Joel A.; Rovick, Allen A.

    1986-01-01

    Promotes the use of computer-based simulations in the pre-clinical medical curriculum as a means of providing students with opportunities for problem solving. Describes simple simulations of skeletal muscle loads, complex simulations of major organ systems and comprehensive simulation models of the entire human body. (TW)

  5. Application of integrated reservoir management and reservoir characterization to optimize infill drilling. Quarterly progress report, June 13, 1995--September 12, 1995

    SciTech Connect

    Pande, P.K.

    1995-09-12

    At this stage of the reservoir characterization research, the main emphasis is on the geostatistics and reservoir simulation. Progress is reported on geological analysis, reservoir simulation, and reservoir management.

  6. Solution to the indexing problem of frequency domain simulation experiments

    NASA Technical Reports Server (NTRS)

    Mitra, Mousumi; Park, Stephen K.

    1991-01-01

    A frequency domain simulation experiment is one in which selected system parameters are oscillated sinusoidally to induce oscillations in one or more system statistics of interest. A spectral (Fourier) analysis of these induced oscillations is then performed. To perform this spectral analysis, all oscillation frequencies must be referenced to a common, independent variable - an oscillation index. In a discrete-event simulation, the global simulation clock is the most natural choice for the oscillation index. However, past efforts to reference all frequencies to the simulation clock generally yielded unsatisfactory results. The reason for these unsatisfactory results is explained in this paper and a new methodology which uses the simulation clock as the oscillation index is presented. Techniques for implementing this new methodology are demonstrated by performing a frequency domain simulation experiment for a network of queues.

  7. Simulation of Sediment and Cesium Transport in the Ukedo River and the Ogi Dam Reservoir during a Rainfall Event using the TODAM Code

    SciTech Connect

    Onishi, Yasuo; Yokuda, Satoru T.; Kurikami, Hiroshi

    2014-03-28

    The accident at the Fukushima Daiichi Nuclear Power Plant in March 2011 caused widespread environmental contamination. Although decontamination activities have been performed in residential areas of the Fukushima area, decontamination of forests, rivers, and reservoirs is still controversial because of the economical, ecological, and technical difficulties. Thus, an evaluation of contaminant transport in such an environment is important for safety assessment and for implementation of possible countermeasures to reduce radiation exposure to the public. The investigation revealed that heavy rainfall events play a significant role in transporting radioactive cesium deposited on the land surface, via soil erosion and sediment transport in rivers. Therefore, we simulated the sediment and cesium transport in the Ukedo River and its tributaries in Fukushima Prefecture, including the Ogaki Dam Reservoir, and the Ogi Dam Reservoir of the Oginosawa River in Fukushima Prefecture during and after a heavy rainfall event by using the TODAM (Time-dependent, One-dimensional Degradation And Migration) code. The main outcomes are the following: • Suspended sand is mostly deposited on the river bottom. Suspended silt and clay, on the other hand, are hardly deposited in the Ukedo River and its tributaries except in the Ogaki Dam Reservoir in the Ukedo River even in low river discharge conditions. • Cesium migrates mainly during high river discharge periods during heavy rainfall events. Silt and clay play more important roles in cesium transport to the sea than sand does. • The simulation results explain variations in the field data on cesium distributions in the river. Additional field data currently being collected and further modeling with these data may shed more light on the cesium distribution variations. • Effects of 40-hour heavy rainfall events on clay and cesium transport continue for more than a month. This is because these reservoirs slow down the storm-induced high

  8. Use of Flight Simulators for Pilot-Control Problems

    NASA Technical Reports Server (NTRS)

    Rathert, George A., Jr.; Creer, Brent Y.; Douvillier, Joseph G., Jr.

    1959-01-01

    Comparisons have been made between actual flight results and results obtained with fixed and moving flight simulators in a number of phases of flying airplanes with a wide range of characteristics. These results have been used to study the importance of providing motion stimuli in a simulator in order that the pilot operate the simulator in a realistic manner. Regions of airplane characteristics where motion stimuli are either mandatory or desirable are indicated.

  9. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly report, July 1--September 30, 1997

    SciTech Connect

    Allison, M.L.

    1997-11-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Two activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone: (1) evaluation of the Ivie Creek and Willow Springs Wash case-study areas and (2) technology transfer.

  10. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly report, April 1--June 30, 1998

    SciTech Connect

    Chidsey, T.C. Jr.

    1998-07-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. Two activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone: (1) preparation of the project final report and (2) technology transfer.

  11. Session: Reservoir Technology

    SciTech Connect

    Renner, Joel L.; Bodvarsson, Gudmundur S.; Wannamaker, Philip E.; Horne, Roland N.; Shook, G. Michael

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five papers: ''Reservoir Technology'' by Joel L. Renner; ''LBL Research on the Geysers: Conceptual Models, Simulation and Monitoring Studies'' by Gudmundur S. Bodvarsson; ''Geothermal Geophysical Research in Electrical Methods at UURI'' by Philip E. Wannamaker; ''Optimizing Reinjection Strategy at Palinpinon, Philippines Based on Chloride Data'' by Roland N. Horne; ''TETRAD Reservoir Simulation'' by G. Michael Shook

  12. HEC Activities in Reservoir Analysis.

    DTIC Science & Technology

    1980-06-01

    June 1979. Now, HEC-5, "Simulation of Flood Con- trol and Conservation Systems," (9) is our primary reservoir simulation program. Since its June release...are being incorporated into the reservoir simulation model HEC-5. The objective is to provide a computer program and methodology for total water

  13. Computer simulation of plasma and N-body problems

    NASA Technical Reports Server (NTRS)

    Harries, W. L.; Miller, J. B.

    1975-01-01

    The following FORTRAN language computer codes are presented: (1) efficient two- and three-dimensional central force potential solvers; (2) a three-dimensional simulator of an isolated galaxy which incorporates the potential solver; (3) a two-dimensional particle-in-cell simulator of the Jeans instability in an infinite self-gravitating compressible gas; and (4) a two-dimensional particle-in-cell simulator of a rotating self-gravitating compressible gaseous system of which rectangular coordinate and superior polar coordinate versions were written.

  14. [Landscape pattern change and its simulation forecast in Zigui County of Three Gorges Reservoir Area].

    PubMed

    Jiang, Huan-Huan; Li, Ji-Hong; Fan, Wen-Yi; Bao, Chen-Guang

    2009-02-01

    Based on the TM images of 1987 and 2002, the landscape pattern change of Zigui County from 1987 to 2002 was analyzed by using landscape index method; and the simulation forecast of this change in next 50 years was conducted by using Markov model. The results showed that in 1987-2002, the landscape pattern of Zigui County changed dramatically. The area of sparse wood land increased greatly while that of upland and shrub land decreased obviously, and the distribution of the areas of different landscape types tended to balance. The average shape index of landscape had an overall decline, which was represented by the concentrated and connected distribution of different landscape types, simplification of landscape shape, and obvious human interference. As a whole, the landscape diversity and fragmentation in Zigui County were improved to some extent. In next 50 years, the area of sparse wood land in Zigui would have a rapid increase, followed by that of forestland, while the areas of upland and shrub land would be declining, and the other landscape types would have a less fluctuation in their areas. The main driving forces of the landscape pattern change in Zigui were the relocation of the County and the implementation of forestry policies.

  15. Numerical simulation of heterogeneous fractured gas reservoir systems with turbulence and closure stress effects

    SciTech Connect

    Allam, A.M.

    1982-01-01

    Although techniques for designing a fracture treatment are available, the intended results of these techniques are often not attained. The evaluation of fracturing treatments on low permeability gas wells is required to both optimize the fracturing design and form prediction calculations of a treatments effect. This study primarily investigates the effect of fracture height on the performance of vertically fractured wells. The effects of layered media, turbulance, and closure pressure are included in this work. Consider that a well, intercepted by a vertical fracture, is in the center of a squared drainage system with closed outer boundary. Any increase in well productivity will be determined by fracture parameters, which are: fracture length, height, fracture conductivity, and location of the fracture in the formaton. On the basis of the analysis of fluid flow in porous media, the problem solving technique used in this study is the numerical method. A three-dimensional finite difference fully implicit model was written for this. In addition, the Sparse Matrix technique was used as a solver. Furthermore, Slices Source Over Relaxation was used as an iterative method for solving routines. Presented here are the numerical results of the three-dimensional model for a well intercepting a vertical fracture wth finite conductivity. The results are presented in the general form of dimensionless variables. Type curves considering the effect of fracture height on well performance are included. In addition, type curves for turbulent flow in the fracture are also obtained. Finally, other important contributions of this work are the data showing the effect of layered formation on fractured well performance.

  16. The Wooly Mammoth as a Computer-Simulated Scientific Problem-Solving Tool.

    ERIC Educational Resources Information Center

    Szabo, Michael

    Mammo I and Mammo II are two versions of a computer simulation based upon scientific problems surrounding the finds of carcasses of the Wooly Mammoth in Siberia. The simulation program consists of two parts: the data base and program logic. The purpose of the data pieces is to provide data of an informative nature and to enable problem solvers to…

  17. Design and Application of Interactive Simulations in Problem-Solving in University-Level Physics Education

    ERIC Educational Resources Information Center

    Ceberio, Mikel; Almudí, José Manuel; Franco, Ángel

    2016-01-01

    In recent years, interactive computer simulations have been progressively integrated in the teaching of the sciences and have contributed significant improvements in the teaching-learning process. Practicing problem-solving is a key factor in science and engineering education. The aim of this study was to design simulation-based problem-solving…

  18. A global optimization algorithm for simulation-based problems via the extended DIRECT scheme

    NASA Astrophysics Data System (ADS)

    Liu, Haitao; Xu, Shengli; Wang, Xiaofang; Wu, Junnan; Song, Yang

    2015-11-01

    This article presents a global optimization algorithm via the extension of the DIviding RECTangles (DIRECT) scheme to handle problems with computationally expensive simulations efficiently. The new optimization strategy improves the regular partition scheme of DIRECT to a flexible irregular partition scheme in order to utilize information from irregular points. The metamodelling technique is introduced to work with the flexible partition scheme to speed up the convergence, which is meaningful for simulation-based problems. Comparative results on eight representative benchmark problems and an engineering application with some existing global optimization algorithms indicate that the proposed global optimization strategy is promising for simulation-based problems in terms of efficiency and accuracy.

  19. Reservoir System Regulation for Water Quality Control.

    DTIC Science & Technology

    1983-03-01

    Davis, California 95616. [PHASE I!- 1979 SINGLE RESERVOIR SIMULATION FOR WATER TEMPERATURE PHASE 31- 1980 TWO RESERVOIR SIMULATION FOR WATER TEMPERATURE...AND SEVEN CONSTITUENTS 1981 FIELD TESTING AND MINOR MODIFICATIONS ’IFI PHASE 3nm- 1982 TEN RESERVOIR SIMULATION FOR WATER TEMPERATURE AND SEVEN

  20. An Elevated Reservoir of Air Pollutants over the Mid-Atlantic States During the 2011 DISCOVER-AQ Campaign: Airborne Measurements and Numerical Simulations

    NASA Technical Reports Server (NTRS)

    He, Hao; Loughner, Christopher P.; Stehr, Jeffrey W.; Arkinson, Heather L.; Brent, Lacey C.; Follette-Cook, Melanie B.; Tzortziou, Maria A.; Pickering, Kenneth E.; Thompson, Anne M.; Martins, Douglas K.; Diskin, Glenn S.; Anderson, Bruce E.; Crawford, James H.; Weinheimer, Andrew J.; Lee, Pius; Hains, Jennifer C.; Dickerson, Russell R.

    2013-01-01

    During a classic heat wave with record high temperatures and poor air quality from July 18 to 23, 2011, an elevated reservoir of air pollutants was observed over and downwind of Baltimore, MD, with relatively clean conditions near the surface. Aircraft and ozonesonde measurements detected approximately 120 parts per billion by volume ozone at 800 meters altitude, but approximately 80 parts per billion by volume ozone near the surface. High concentrations of other pollutants were also observed around the ozone peak: approximately 300 parts per billion by volume CO at 1200 meters, approximately 2 parts per billion by volume NO2 at 800 meters, approximately 5 parts per billion by volume SO2 at 600 meters, and strong aerosol optical scattering (2 x 10 (sup 4) per meter) at 600 meters. These results suggest that the elevated reservoir is a mixture of automobile exhaust (high concentrations of O3, CO, and NO2) and power plant emissions (high SO2 and aerosols). Back trajectory calculations show a local stagnation event before the formation of this elevated reservoir. Forward trajectories suggest an influence on downwind air quality, supported by surface ozone observations on the next day over the downwind PA, NJ and NY area. Meteorological observations from aircraft and ozonesondes show a dramatic veering of wind direction from south to north within the lowest 5000 meters, implying that the development of the elevated reservoir was caused in part by the Chesapeake Bay breeze. Based on in situ observations, Community Air Quality Multi-scale Model (CMAQ) forecast simulations with 12 kilometers resolution overestimated surface ozone concentrations and failed to predict this elevated reservoir; however, CMAQ research simulations with 4 kilometers and 1.33 kilometers resolution more successfully reproduced this event. These results show that high resolution is essential for resolving coastal effects and predicting air quality for cities near major bodies of water such as

  1. Impacts of boreal hydroelectric reservoirs on seasonal climate and precipitation recycling as simulated by the CRCM5: a case study of the La Grande River watershed, Canada

    NASA Astrophysics Data System (ADS)

    Irambona, C.; Music, B.; Nadeau, D. F.; Mahdi, T. F.; Strachan, I. B.

    2016-12-01

    Located in northern Quebec, Canada, eight hydroelectric reservoirs of a 9782-km2 maximal area cover 6.4% of the La Grande watershed. This study investigates the changes brought by the impoundment of these reservoirs on seasonal climate and precipitation recycling. Two 30-year climate simulations, corresponding to pre- and post-impoundment conditions, were used. They were generated with the fifth-generation Canadian Regional Climate Model (CRCM5), fully coupled to a 1D lake model (FLake). Seasonal temperatures and annual energy budget were generally well reproduced by the model, except in spring when a cold bias, probably related to the overestimation of snow cover, was seen. The difference in 2-m temperature shows that reservoirs induce localized warming in winter (+0.7 ± 0.02 °C) and cooling in the summer (-0.3 ± 0.02 °C). The available energy at the surface increases throughout the year, mostly due to a decrease in surface albedo. Fall latent and sensible heat fluxes are enhanced due to additional energy storage and availability in summer and spring. The changes in precipitation and runoff are within the model internal variability. At the watershed scale, reservoirs induce an additional evaporation of only 5.9 mm year-1 (2%). We use Brubaker's precipitation recycling model to estimate how much of the precipitation is recycled within the watershed. In both simulations, the maximal precipitation recycling occurs in July (less than 6%), indicating weak land-atmosphere coupling. Reservoirs do not seem to affect this coupling, as precipitation recycling only decreased by 0.6% in July.

  2. An elevated reservoir of air pollutants over the Mid-Atlantic States during the 2011 DISCOVER-AQ campaign: Airborne measurements and numerical simulations

    NASA Astrophysics Data System (ADS)

    He, Hao; Loughner, Christopher P.; Stehr, Jeffrey W.; Arkinson, Heather L.; Brent, Lacey C.; Follette-Cook, Melanie B.; Tzortziou, Maria A.; Pickering, Kenneth E.; Thompson, Anne M.; Martins, Douglas K.; Diskin, Glenn S.; Anderson, Bruce E.; Crawford, James H.; Weinheimer, Andrew J.; Lee, Pius; Hains, Jennifer C.; Dickerson, Russell R.

    2014-03-01

    During a classic heat wave with record high temperatures and poor air quality from July 18 to 23, 2011, an elevated reservoir of air pollutants was observed over and downwind of Baltimore, MD, with relatively clean conditions near the surface. Aircraft and ozonesonde measurements detected ˜120 ppbv ozone at 800 m altitude, but ˜80 ppbv ozone near the surface. High concentrations of other pollutants were also observed around the ozone peak: ˜300 ppbv CO at 1200 m, ˜2 ppbv NO2 at 800 m, ˜5 ppbv SO2 at 600 m, and strong aerosol optical scattering (2 × 10-4 m-1) at 600 m. These results suggest that the elevated reservoir is a mixture of automobile exhaust (high concentrations of O3, CO, and NO2) and power plant emissions (high SO2 and aerosols). Back trajectory calculations show a local stagnation event before the formation of this elevated reservoir. Forward trajectories suggest an influence on downwind air quality, supported by surface ozone observations on the next day over the downwind PA, NJ and NY area. Meteorological observations from aircraft and ozonesondes show a dramatic veering of wind direction from south to north within the lowest 5000 m, implying that the development of the elevated reservoir was caused in part by the Chesapeake Bay breeze. Based on in situ observations, CMAQ forecast simulations with 12 km resolution overestimated surface ozone concentrations and failed to predict this elevated reservoir; however, CMAQ research simulations with 4 km and 1.33 km resolution more successfully reproduced this event. These results show that high resolution is essential for resolving coastal effects and predicting air quality for cities near major bodies of water such as Baltimore on the Chesapeake Bay and downwind areas in the Northeast.

  3. Dynamic model for simulating the acceptance problem of nuclear energy

    SciTech Connect

    Seifritz, W.; Mennig, J.

    1987-01-01

    Nonlinear dynamics are attaining greater interest in different fields of application. Since the early 1980s, these methods have been applied intensively to a variety of very different general problems, such as the description of political and economic processes as well as the symbiotic behavior in the flora and fauna. The authors have tried to apply these mathematical methods to the dynamic behavior inherent in the problem of the acceptance of nuclear energy. The model, which simplifies the real situation, is two-dimensional and describes the symbiosis of two individuals: the capacity of nuclear power plants P and their acceptance A by the public. It is clear that in reality the acceptance problem depends on a series of other variables as well. However, it is believed that our investigations reveal some universal properties inherent to our socioeconomic system: nonlinearity and dissipative processes.

  4. Design and Performance Frameworks for Constructing Problem-Solving Simulations

    ERIC Educational Resources Information Center

    Stevens, Rons; Palacio-Cayetano, Joycelin

    2003-01-01

    Rapid advancements in hardware, software, and connectivity are helping to shorten the times needed to develop computer simulations for science education. These advancements, however, have not been accompanied by corresponding theories of how best to design and use these technologies for teaching, learning, and testing. Such design frameworks…

  5. Simulated effects of proposed Arkansas Valley Conduit on hydrodynamics and water quality for projected demands through 2070, Pueblo Reservoir, southeastern Colorado

    USGS Publications Warehouse

    Ortiz, Roderick F.

    2013-01-01

    The purpose of the Arkansas Valley Conduit (AVC) is to deliver water for municipal and industrial use within the boundaries of the Southeastern Colorado Water Conservancy District. Water supplied through the AVC would serve two needs: (1) to supplement or replace existing poor-quality water to communities downstream from Pueblo Reservoir; and (2) to meet a portion of the AVC participants’ projected water demands through 2070. The Bureau of Reclamation (Reclamation) initiated an Environmental Impact Statement (EIS) to address the potential environmental consequences associated with constructing and operating the proposed AVC, entering into a conveyance contract for the Pueblo Dam north-south outlet works interconnect (Interconnect), and entering into a long-term excess capacity master contract (Master Contract). Operational changes, as a result of implementation of proposed EIS alternatives, could change the hydrodynamics and water-quality conditions in Pueblo Reservoir. An interagency agreement was initiated between Reclamation and the U.S. Geological Survey to accurately simulate hydrodynamics and water quality in Pueblo Reservoir for projected demands associated with four of the seven proposed EIS alternatives. The four alternatives submitted to the USGS for scenario simulation included various combinations (action or no action) of the proposed Arkansas Valley Conduit, Master Contract, and Interconnect options. The four alternatives were the No Action, Comanche South, Joint Use Pipeline North, and Master Contract Only. Additionally, scenario simulations were done that represented existing conditions (Existing Conditions scenario) in Pueblo Reservoir. Water-surface elevations, water temperature, dissolved oxygen, dissolved solids, dissolved ammonia, dissolved nitrate, total phosphorus, total iron, and algal biomass (measured as chlorophyll-a) were simulated. Each of the scenarios was simulated for three contiguous water years representing a wet, average, and dry

  6. Identifying Students with Chemical Health Problems: Background and Simulation.

    ERIC Educational Resources Information Center

    Maine State Dept. of Educational and Cultural Services, Augusta. Div. of Alcohol and Drug Education Services.

    This document discusses the role of school personnel in identifying and referring students with chemical health problems. It introduces the topic by stating that school personnel should be aware of how to deal with students who have violated school rules and those who are seeking help. It states that they should know how to draw the line…

  7. A simulation-optimization approach to retrieve reservoir releasing strategies under the trade-off objectives considering flooding, sedimentation, turbidity and water supply during typhoons

    NASA Astrophysics Data System (ADS)

    Huang, C. L.; Hsu, N. S.; Yeh, W. W. G.; You, G. J. Y.

    2014-12-01

    This study develops a simulation-optimization approach for retrieving optimal multi-layer reservoir conjunctive release strategies considering the natural hazards of sedimentation, turbidity and flooding during typhoon invasion. The purposes of the developed approach are: (1) to apply WASP-based fluid dynamic sediment concentration simulation model and the developed extracting method of ideal releasing practice to search the optimal initial solution for optimization; and (2) to construct the replacing sediment concentration simulation model which embedded in the optimization model. In this study, the optimization model is solved by tabu search, and the optimized releasing hydrograph is then used for construction of the decision model. This study applies Adaptive Network-based Fuzzy Inference System (ANFIS) and Real-time Recurrent Learning Neural Network (RTRLNN) as construction tool of the concentration simulation model for total suspended solids. This developed approach is applied to the Shihmen Reservoir basin, Taiwan. The assessment index of operational outcome of multi-purpose multi-layer conjunctive releasing are maximum sediment concentration at Yuan-Shan weir, sediment removed ratio, highest water level at Shan-Yin Bridge, and final water level in Shihmen reservoir. The analyzed and optimizing results shows the following: (1) The multi-layer releasing during the stages before flood coming and before peak flow possess high potential for flood detention and sedimentation control; and during the stages after peak flow, for turbidity control and storage; (2) The ability of error toleration and adaption of ANFIS is superior, so ANFIS-based sediment concentration simulation model surpass RTRLNN-based model on simulating the mechanism and characteristics of sediment transport; and (3) The developed approach can effectively and automatically retrieve the optimal multi-layer releasing strategies under the trade-off control between flooding, sedimentation, turbidity

  8. Fundamental problems in porous materials: Experiments & computer simulation

    NASA Astrophysics Data System (ADS)

    Xu, Zhanping

    Porous materials have attracted massive scientific and technological interest because of their extremely high surface-to-volume ratio, molecular tunability in construction, and surface-based applications. Through my PhD work, porous materials were engineered to meet the design in selective binding, self-healing, and energy damping. For example, crystalline MOFs with pore size spanning from a few angstroms to a couple of nanometers were chemically engineered to show 120 times more efficiency in binding of large molecules. In addition, we found building blocks released from those crystals can be further patched back through a healing process at ambient and low temperatures down to -56 °C. When building blocks are replaced with graphenes, ultra-flyweight aerogels with pore size larger than 100 nm were made to delay shock waves. More stable rigid porous metal with larger pores (~um) was also fabricated, and its performance and survivability are under investigation. Aside from experimental studies, we also successfully applied numerical simulations to study the mutual interaction between the nonplanar liquid-solid interface and colloidal particles during the freezing of the colloidal suspensions. Colloidal particles can be either rejected or engulfed by the evolving interface depending on the freezing speed and strength of interface-particle interaction. Our interactive simulation was achieved by programming both simulation module and visualization module on high performance GPU devices.

  9. Simulation, Control, and Applications for Flow and Scattering Problems

    DTIC Science & Technology

    2015-04-10

    and Optimization (08 2011) Kazufumi Ito, Tomoya Takeuchi. CIP immersed interface methods for hyperbolic equations withdiscontinuous coefficients ...augmented variables along the interface between the fluid flow and the porous media so that the problem can be decoupled as several Poisson equations . The...computational fluid dynamics and control of incompressible flows modeled by Navier-Stokes equations . Under the support of the current ARO grant, we

  10. The simulation research of dissolved nitrogen and phosphorus non-point source pollution in Xiao-Jiang watershed of Three Gorges Reservoir area.

    PubMed

    Wu, Lei; Long, Tian-Yu; Li, Chong-Ming

    2010-01-01

    Xiao-jiang, with a basin area of almost 5,276 km(2) and a length of 182.4 km, is located in the center of the Three Gorges Reservoir Area, and is the largest tributary of the central section in Three Gorges Reservoir Area, farmland accounts for a large proportion of Xiao-jiang watershed, and the hilly cropland of purple soil is much of the farmland of the watershed. After the second phase of water storage in the Three Gorges Reservoir, the majority of sub-rivers in the reservoir area experienced eutrophication phenomenon frequently, and non-point source (NPS) pollution has become an important source of pollution in Xiao-jiang Watershed. Because dissolved nitrogen and phosphorus non-point source pollution are related to surface runoff and interflow, using climatic, topographic and land cover data from the internet and research institutes, the Semi-Distributed Land-use Runoff Process (SLURP) hydrological model was introduced to simulate the complete hydrological cycle of the Xiao-jiang Watershed. Based on the SLURP distributed hydrological model, non-point source pollution annual output load models of land use and rural residents were respectively established. Therefore, using GIS technology, considering the losses of dissolved nitrogen and phosphorus in the course of transport, a dissolved non-point source pollution load dynamic model was established by the organic coupling of the SLURP hydrological model and land-use output model. Through the above dynamic model, the annual dissolved non-point source nitrogen and phosphorus pollution output as well as the load in different types were simulated and quantitatively estimated from 2001 to 2008, furthermore, the loads of Xiao-jiang Watershed were calculated and expressed by temporal and spatial distribution in the Three Gorges Reservoir Area. The simulation results show that: the temporal changes of dissolved nitrogen and phosphorus load in the watershed are close to the inter-annual changes of rainfall runoff, and the

  11. Simulation Model for Scenario Optimization of the Ready-Mix Concrete Delivery Problem

    NASA Astrophysics Data System (ADS)

    Galić, Mario; Kraus, Ivan

    2016-12-01

    This paper introduces a discrete simulation model for solving routing and network material flow problems in construction projects. Before the description of the model a detailed literature review is provided. The model is verified using a case study of solving the ready-mix concrete network flow and routing problem in metropolitan area in Croatia. Within this study real-time input parameters were taken into account. Simulation model is structured in Enterprise Dynamics simulation software and Microsoft Excel linked with Google Maps. The model is dynamic, easily managed and adjustable, but also provides good estimation for minimization of costs and realization time in solving discrete routing and material network flow problems.

  12. Simulated paraplegia: an occasional problem for the neurosurgeon.

    PubMed Central

    Maurice-Williams, R S; Marsh, H

    1985-01-01

    Fourteen cases of simulated paraplegia and tetraplegia encountered amongst 4,800 neurosurgical admissions are described. The classification of such cases is difficult. Use of the term "hysteria" depends on whether the behaviour is judged to be conscious or not, but this can rarely be decided. In most of the patients the paralysis was of relatively short duration and recovered rapidly with simple methods of treatment which permitted this to occur without loss of face, but such cases presenting as acute neurological emergencies represent only one relatively simple form of pretended or "hysterical" illness. Many of these patients are probably never seen by psychiatrists. PMID:4031935

  13. Reservoir System Analysis for Water Quality.

    DTIC Science & Technology

    1984-08-01

    reservoirs on flows and damages in the system. The program should also be useful In selecting the 2 PHASE Z- 1979 SINGLE RESERVOIR SIMULATION FOR WATER...TEMPERATURE PHASE H- 1980 TWO RESERVOIR SIMULATION FOR WATER TEMPERATURE AND SEVEN CONSTITUENTS 1981 FIELD TESTING AND MINOR MODIFICATIONS PHASE M- 1982...TEN RESERVOIR SIMULATION FOR WATER TEMPERATURE AND . TAB SEVEN CONSTITUENTS 1P.IX Ot1Oun4 ___ ___ __ __ ___ __ ___ __ ___ _ .zt ltl@a’tlo@ . 113

  14. Improved Efficiency of Miscible CO2 Floods and Enhanced Prospects for CO2 Flooding Heterogeneous Reservoirs

    SciTech Connect

    Grigg, Reid B.; Schechter, David S.

    1999-10-15

    The goal of this project is to improve the efficiency of miscible CO2 floods and enhance the prospects for flooding heterogeneous reservoirs. This report provides results of the second year of the three-year project that will be exploring three principles: (1) Fluid and matrix interactions (understanding the problems). (2) Conformance control/sweep efficiency (solving the problems. 3) Reservoir simulation for improved oil recovery (predicting results).

  15. Influence of reservoir conditions on multiphase flow in natural sandstone using lattice Boltzmann simulation: Investigation of suitable conditions in CCS and EOR

    NASA Astrophysics Data System (ADS)

    Tsuji, T.; Jiang, F.; Christensen, K. T.

    2015-12-01

    Microscopic two-phase fluid behavior in porous media is influenced by reservoir temperature, interfacial tension, pore structure, and porous medium characteristics (e.g., wettability), which vary significantly from one reservoir to the next. Pore-scale interfacial instabilities, such as snap-off and fingering phenomena, influence the stability, injectivity, mobility, and saturation within the reservoir. Therefore, understanding microscopic multiphase flow in porous media is crucial to estimating critical reservoir-scale characteristics, including storage capacity, leakage risk, and storage efficiency. Here we calculated fluid displacements within 3D pore spaces of natural sandstone using two-phase lattice Boltzmann (LB) simulation and characterized the influence of reservoir conditions upon multiphase flow. We classified the two-phase flow behavior that occurred under various conditions into three typical fluid displacement patterns on the diagram of capillary number (Ca) and viscosity ratio of the two fluids (M). Then the saturation of the nonwetting phase was calculated and mapped on the Ca-M diagram. The saturation map is useful to investigate suitable conditions in CCS and EOR. We further characterized dynamic pore-filling events (i.e., Haines jumps) from the fluid pressure variation. The results revealed the onset of capillary fingering in natural rock at a higher Ca than previously reported for homogeneous porous media, with the crossover region between typical displacement patterns much broader than in a homogeneous granular model. These differences between two-phase flow in natural rock and in a homogeneous porous structure could be the result of the heterogeneity of the natural rock.

  16. Application of Integrated Reservoir Management and Reservoir Characterization to Optimize Infill Drilling

    SciTech Connect

    1998-01-01

    Infill drilling if wells on a uniform spacing without regard to reservoir performance and characterization foes not optimize reservoir development because it fails to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, and carbonate reservoirs in particular. New and emerging technologies, such as geostatistical modeling, rigorous decline curve analysis, reservoir rock typing, and special core analysis can be used to develop a 3-D simulation model for prediction of infill locations.

  17. Application of Integrated Reservoir management and Reservoir Characterization to Optimize Infill Drilling

    SciTech Connect

    B. Pregger; D. Davies; D. Moore; G. Freeman; J. Callard; J.W. Nevans; L. Doublet; R. Vessell; T. Blasingame

    1997-08-31

    Infill drilling if wells on a uniform spacing without regard to reservoir performance and characterization foes not optimize reservoir development because it fails to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, and carbonate reservoirs in particular. New and emerging technologies, such as geostatistical modeling, rigorous decline curve analysis, reservoir rock typing, and special core analysis can be used to develop a 3-D simulation model for prediction of infill locations.

  18. Application of Integrated Reservoir Management and Reservoir Characterization to Optimize Infill Drilling

    SciTech Connect

    1998-03-12

    Infill drilling if wells on a uniform spacing without regard to reservoir performance and characterization foes not optimize reservoir development because it fails to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, and carbonate reservoirs in particular. New and emerging technologies, such as geostatistical modeling, rigorous decline curve analysis, reservoir rock typing, and special core analysis can be used to develop a 3-D simulation model for prediction of infill locations.

  19. The cascade of reservoirs of the ``Mayak`` Plant: Case history and the first version of a computer simulator

    SciTech Connect

    Mironenko, M.V.; Spasennykh, M.Yu.; Polyakov, V.B.

    1994-07-01

    The improvement of the ecological conditions at waste storing reservoirs is an important task of the restoration activity at Production Association (PA) ``Mayak`` (South Urals). The radionuclides mostly {sup 90}Sr, {sup 137}Cs, and chemical pollutants deposited in the reservoir water and in the bottom sediment are very dangerous sources for the contamination of Techa River below the reservoirs and the contamination of groundwater in the surrounding formations. The spreading of radioactive contaminants has both hydrogeological and the chemical features. The thermodynamic approach used to account for physical-chemical interactions between water and the bed rocks based on Gibbs free energy minimization of multicomponent system (H-O-Ca-Mg-K-Na-S-Cl-C-Sr) permitted the authors to calculate the corresponding ionic and complex species existing in the solutions, and to characterize the processes of precipitation and dissolution. The model takes into account the input and output surface and underground water fluxes, mass exchange of the reservoir with the atmosphere, radioactive decay and water-sediment interaction including processes of the {sup 90}Sr and {sup 137}Cs sorption on the grains of the sediment and the radionuclide diffusion in the pore water. This model was used in the retrospective and prognosis calculations of radiation and hydrochemical regime of these reservoirs.

  20. Methodology for analysis and simulation of large multidisciplinary problems

    NASA Technical Reports Server (NTRS)

    Russell, William C.; Ikeda, Paul J.; Vos, Robert G.

    1989-01-01

    The Integrated Structural Modeling (ISM) program is being developed for the Air Force Weapons Laboratory and will be available for Air Force work. Its goal is to provide a design, analysis, and simulation tool intended primarily for directed energy weapons (DEW), kinetic energy weapons (KEW), and surveillance applications. The code is designed to run on DEC (VMS and UNIX), IRIS, Alliant, and Cray hosts. Several technical disciplines are included in ISM, namely structures, controls, optics, thermal, and dynamics. Four topics from the broad ISM goal are discussed. The first is project configuration management and includes two major areas: the software and database arrangement and the system model control. The second is interdisciplinary data transfer and refers to exchange of data between various disciplines such as structures and thermal. Third is a discussion of the integration of component models into one system model, i.e., multiple discipline model synthesis. Last is a presentation of work on a distributed processing computing environment.

  1. Numerical simulation of shock/bubble-cloud interaction problems

    NASA Astrophysics Data System (ADS)

    Ando, Keita; Colonius, Tim; Brennen, Christopher

    2009-11-01

    The interaction of a shock wave with a dilute bubble cloud is computed using a continuum two-phase model incorporating the effect of a distribution of nuclei sizes. The bubble dynamics are evaluated using a Rayleigh-Plesset-type equation including the effects of heat transfer, liquid viscosity and compressibility. A finite-volume WENO scheme coupled with an approximate HLLC Riemann solver is developed to solve the shock problems. Linear and shock wave propagation through a one-dimensional bubble screen is computed and the effect of phase cancellations among the different-sized bubbles is quantified. The size distribution in the screen is found to increase the cushioning of the shock loading. Computations of shock/bubble-cloud interaction in two dimensions are also presented.

  2. Integrating Problem-Based Learning and Simulation: Effects on Student Motivation and Life Skills.

    PubMed

    Roh, Young Sook; Kim, Sang Suk

    2015-07-01

    Previous research has suggested that a teaching strategy integrating problem-based learning and simulation may be superior to traditional lecture. The purpose of this study was to assess learner motivation and life skills before and after taking a course involving problem-based learning and simulation. The design used repeated measures with a convenience sample of 83 second-year nursing students who completed the integrated course. Data from a self-administered questionnaire measuring learner motivation and life skills were collected at pretest, post-problem-based learning, and post-simulation time points. Repeated-measures analysis of variance determined that the mean scores for total learner motivation (F=6.62, P=.003), communication (F=8.27, P<.001), problem solving (F=6.91, P=.001), and self-directed learning (F=4.45, P=.016) differed significantly between time points. Post hoc tests using the Bonferroni correction revealed that total learner motivation and total life skills significantly increased both from pretest to postsimulation and from post-problem-based learning test to postsimulation test. Subscales of learner motivation and life skills, intrinsic goal orientation, self-efficacy for learning and performance, problem-solving skills, and self-directed learning skills significantly increased both from pretest to postsimulation test and from post-problem-based learning test to post-simulation test. The results demonstrate that an integrating problem-based learning and simulation course elicits significant improvement in learner motivation and life skills. Simulation plus problem-based learning is more effective than problem-based learning alone at increasing intrinsic goal orientation, task value, self-efficacy for learning and performance, problem solving, and self-directed learning.

  3. FLAG Simulations of the Elasticity Test Problem of Gavrilyuk et al.

    SciTech Connect

    Kamm, James R.; Runnels, Scott R.; Canfield, Thomas R.; Carney, Theodore C.

    2014-04-23

    This report contains a description of the impact problem used to compare hypoelastic and hyperelastic material models, as described by Gavrilyuk, Favrie & Saurel. That description is used to set up hypoelastic simulations in the FLAG hydrocode.

  4. An Advanced Reservoir Simulator for Tracer Transport in Multicomponent Multiphase Compositional Flow and Applications to the Cranfield CO2 Sequestration Site

    NASA Astrophysics Data System (ADS)

    Moortgat, J.

    2015-12-01

    Reservoir simulators are widely used to constrain uncertainty in the petrophysical properties of subsurface formations by matching the history of injection and production data. However, such measurements may be insufficient to uniquely characterize a reservoir's properties. Monitoring of natural (isotopic) and introduced tracers is a developing technology to further interrogate the subsurface for applications such as enhanced oil recovery from conventional and unconventional resources, and CO2 sequestration. Oak Ridge National Laboratory has been piloting this tracer technology during and following CO2 injection at the Cranfield, Mississippi, CO2 sequestration test site. Two campaigns of multiple perfluorocarbon tracers were injected together with CO2 and monitored at two wells at 68 m and 112 m from the injection site. The tracer data suggest that multiple CO2 flow paths developed towards the monitoring wells, indicative of either channeling through high permeability pathways or of fingering. The results demonstrate that tracers provide an important complement to transient pressure data. Numerical modeling is essential to further explain and interpret the observations. To aid the development of tracer technology, we enhanced a compositional multiphase reservoir simulator to account for tracer transport. Our research simulator uses higher-order finite element (FE) methods that can capture the small-scale onset of fingering on the coarse grids required for field-scale modeling, and allows for unstructured grids and anisotropic heterogeneous permeability fields. Mass transfer between fluid phases and phase behavior are modeled with rigorous equation-of-state based phase-split calculations. We present our tracer simulator and preliminary results related to the Cranfield experiments. Applications to noble gas tracers in unconventional resources are presented by Darrah et al.

  5. Multi-time scale Climate Informed Stochastic Hybrid Simulation-Optimization Model (McISH model) for Multi-Purpose Reservoir System

    NASA Astrophysics Data System (ADS)

    Lu, M.; Lall, U.

    2013-12-01

    In order to mitigate the impacts of climate change, proactive management strategies to operate reservoirs and dams are needed. A multi-time scale climate informed stochastic model is developed to optimize the operations for a multi-purpose single reservoir by simulating decadal, interannual, seasonal and sub-seasonal variability. We apply the model to a setting motivated by the largest multi-purpose dam in N. India, the Bhakhra reservoir on the Sutlej River, a tributary of the Indus. This leads to a focus on timing and amplitude of the flows for the monsoon and snowmelt periods. The flow simulations are constrained by multiple sources of historical data and GCM future projections, that are being developed through a NSF funded project titled 'Decadal Prediction and Stochastic Simulation of Hydroclimate Over Monsoon Asia'. The model presented is a multilevel, nonlinear programming model that aims to optimize the reservoir operating policy on a decadal horizon and the operation strategy on an updated annual basis. The model is hierarchical, in terms of having a structure that two optimization models designated for different time scales are nested as a matryoshka doll. The two optimization models have similar mathematical formulations with some modifications to meet the constraints within that time frame. The first level of the model is designated to provide optimization solution for policy makers to determine contracted annual releases to different uses with a prescribed reliability; the second level is a within-the-period (e.g., year) operation optimization scheme that allocates the contracted annual releases on a subperiod (e.g. monthly) basis, with additional benefit for extra release and penalty for failure. The model maximizes the net benefit of irrigation, hydropower generation and flood control in each of the periods. The model design thus facilitates the consistent application of weather and climate forecasts to improve operations of reservoir systems. The

  6. On a model simulating lack of hydraulic connection between a man-made reservoir and the volume of poroelastic rock hosting the focus of a post-impoundment earthquake

    NASA Astrophysics Data System (ADS)

    Chander, Ramesh; Tomar, S. K.

    2016-12-01

    The idea that a direct hydraulic connection between a man-made reservoir and the foci of post-impoundment earthquakes may not exist at all sites is eminently credible on geological grounds. Our aim is to provide a simple earth model and related theory for use during investigations of earthquakes near new man-made reservoirs. We consider a uniform circular reservoir which rests on the top surface of a no-hydraulic-connection earth model (NHCEM). The model comprises a top elastic (E) layer, an intermediate poroelastic (P) layer, and a bottom elastic half space. The focus of a potential earthquake in the P layer is located directly under the reservoir. The E layer disrupts the hydraulic connection between the reservoir and the focus. Depth of water in the reservoir varies as H ' + hcos( ω t). Expressions for reservoir-induced stresses and pore pressure in different layers of the NHCEM are obtained by solving the boundary-value problem invoking full coupling between mean normal stress and pore pressure in the P layer. As an application of the derived mathematical results, we have examined and found that earthquakes on 60∘ normal faults may occur in the P-layer of a selected NHCEM at epochs of low reservoir level if the reservoir lies mostly in the footwall of the fault. The exercise was motivated by observations of such earthquakes under the man-made Lake Mead after it was impounded.

  7. Analysis, preliminary design and simulation systems for control-structure interaction problems

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alvin, Kenneth F.

    1991-01-01

    Software aspects of control-structure interaction (CSI) analysis are discussed. The following subject areas are covered: (1) implementation of a partitioned algorithm for simulation of large CSI problems; (2) second-order discrete Kalman filtering equations for CSI simulations; and (3) parallel computations and control of adaptive structures.

  8. Exploring the Use of Computer Simulation to Evaluate the Implementation of Problem-Solving Consultation

    ERIC Educational Resources Information Center

    Newell, Markeda

    2010-01-01

    The purpose of this study was to examine how school psychologists implemented the problem-solving consultation process within a computer-simulated school environment. Four school psychologists were recruited to complete three simulated consultation cases. The school environment was computer generated and all of the teachers and target students…

  9. Developing Clinical Competency in Crisis Event Management: An Integrated Simulation Problem-Based Learning Activity

    ERIC Educational Resources Information Center

    Liaw, S. Y.; Chen, F. G.; Klainin, P.; Brammer, J.; O'Brien, A.; Samarasekera, D. D.

    2010-01-01

    This study aimed to evaluate the integration of a simulation based learning activity on nursing students' clinical crisis management performance in a problem-based learning (PBL) curriculum. It was hypothesized that the clinical performance of first year nursing students who participated in a simulated learning activity during the PBL session…

  10. Simulation Technique in the Teaching and Testing of Problem-Solving Skills.

    ERIC Educational Resources Information Center

    McGuire, Christine

    This presentation, by an invited speaker at the 46th annual meeting of the National Association for Research in Science Teaching, describes simulation techniques used in the medical education program at the University of Illinois. Medical students interact with simulated patients and acquire problem-solving competencies for use in working with…

  11. The Effect of Simulation Games on the Learning of Computational Problem Solving

    ERIC Educational Resources Information Center

    Liu, Chen-Chung; Cheng, Yuan-Bang; Huang, Chia-Wen

    2011-01-01

    Simulation games are now increasingly applied to many subject domains as they allow students to engage in discovery processes, and may facilitate a flow learning experience. However, the relationship between learning experiences and problem solving strategies in simulation games still remains unclear in the literature. This study, thus, analyzed…

  12. TOUGH Simulations of the Updegraff's Set of Fluid and Heat Flow Problems

    SciTech Connect

    Moridis, G.J.; Pruess , K.

    1992-11-01

    The TOUGH code [Pruess, 1987] for two-phase flow of water, air, and heat in penneable media has been exercised on a suite of test problems originally selected and simulated by C. D. Updegraff [1989]. These include five 'verification' problems for which analytical or numerical solutions are available, and three 'validation' problems that model laboratory fluid and heat flow experiments. All problems could be run without any code modifications (*). Good and efficient numerical performance, as well as accurate results were obtained throughout. Additional code verification and validation problems from the literature are briefly summarized, and suggestions are given for proper applications of TOUGH and related codes.

  13. Navigating the Problem Space: The Medium of Simulation Games in the Teaching of History

    ERIC Educational Resources Information Center

    McCall, Jeremiah

    2012-01-01

    Simulation games can play a critical role in enabling students to navigate the problem spaces of the past while simultaneously critiquing the models designers offer to represent those problem spaces. There is much to be gained through their use. This includes rich opportunities for students to engage the past as independent historians; to consider…

  14. The Obtaining of Oil from an Oil Reservoir.

    ERIC Educational Resources Information Center

    Dawe, R. A.

    1979-01-01

    Discusses the mechanics of how an actual oil reservoir works and provides some technical background in physics. An experiment which simulates an oil reservoir and demonstrates quantitatively all the basic concepts of oil reservoir rock properties is also presented. (HM)

  15. Simulated annealing algorithm for solving chambering student-case assignment problem

    NASA Astrophysics Data System (ADS)

    Ghazali, Saadiah; Abdul-Rahman, Syariza

    2015-12-01

    The problem related to project assignment problem is one of popular practical problem that appear nowadays. The challenge of solving the problem raise whenever the complexity related to preferences, the existence of real-world constraints and problem size increased. This study focuses on solving a chambering student-case assignment problem by using a simulated annealing algorithm where this problem is classified under project assignment problem. The project assignment problem is considered as hard combinatorial optimization problem and solving it using a metaheuristic approach is an advantage because it could return a good solution in a reasonable time. The problem of assigning chambering students to cases has never been addressed in the literature before. For the proposed problem, it is essential for law graduates to peruse in chambers before they are qualified to become legal counselor. Thus, assigning the chambering students to cases is a critically needed especially when involving many preferences. Hence, this study presents a preliminary study of the proposed project assignment problem. The objective of the study is to minimize the total completion time for all students in solving the given cases. This study employed a minimum cost greedy heuristic in order to construct a feasible initial solution. The search then is preceded with a simulated annealing algorithm for further improvement of solution quality. The analysis of the obtained result has shown that the proposed simulated annealing algorithm has greatly improved the solution constructed by the minimum cost greedy heuristic. Hence, this research has demonstrated the advantages of solving project assignment problem by using metaheuristic techniques.

  16. Running in the rain: using a shared simulation to solve open-ended physics problems

    NASA Astrophysics Data System (ADS)

    Scanlon, Eileen; O'Shea, Tim; Smith, Randall; Taylor, Josie; O'Malley, Claire

    1993-03-01

    The five ways of using computer simulations for students learning physics are for `hypothetical' experiments, for `breaking' the laws of nature, for `tidy' experiments, for `instrumental' data capture and display and for direct mathematical `modelling'. This article describes a distributed computer simulation running on linked workstations and reports on students' attempts at solving the `running in the rain' problem. The simulation of the problem is implemented in SharedARK, a prototype technology for allowing students to work together at a distance from each other.

  17. Influence of Height in Simulation of Soil Structure Interaction Problems with Dampers

    NASA Astrophysics Data System (ADS)

    Bogdanovic, Aleksandra; Edip, Kemal; Stojmanovska, Marta

    2016-12-01

    In numerical simulation of soil structure interaction problems the presence of dampers in the frame is an advantage yet a special topic to be considered. This paper presents valuable observation on the dynamic soil structure interaction analysis of multi storey frames and considers the effect of height in simulation of soil structure interaction problems. Comparison of these problems has been done by comparing the obtained results from different set up in the software ANSYS. The results of numerical analysis illustrate that it has to be paid more attention when considering the structures not alone but also considering the effect of soil medium.

  18. Simulated effects of water-level changes in the Mississippi River and Pokegama Reservoir on ground-water levels, Grand Rapids area, Minnesota

    USGS Publications Warehouse

    Jones, Perry M.

    2005-01-01

    The extent of aquifer water-level changes resulting from these river, wetland, and lake water-level changes varied because of the complex hydrogeology of the study area. A 1.00-foot decline in reservoir/river water levels caused a maximum simulated ground-water-level decline in the middle aquifer near Jay Gould and Little Jay Gould Lakes of 1.09 feet and a maximum simulated ground-water-level decline of 1.00 foot in the lower aquifer near Cut-off and Blackwater Lakes. The amount and extent of ground-water-level changes in the middle and lower aquifers can be explained by the thickness, extent, and connectivity of the aquifers. Surface-water/ground-water interactions near wetlands and lakes with water levels unchanged from the calibrated model resulted in small water-table altitude differences among the simulations. Results of the ground-water modeling indicate that lowering of the reservoir and river water levels by 1.00 foot likely will not substantially affect water levels in the middle and lower aquifers.

  19. Effects of an integrated problem-based learning and simulation course for nursing students.

    PubMed

    Roh, Young Sook; Kim, Sang Suk; Kim, Sung Hee

    2014-03-01

    The adaptability of high-fidelity simulations to multiple learning strategies is an essential feature of their effective use, however, little is known about the effects of integration simulations with problem-based learning. The purpose of this study was to identify the effects of an integrated course with problem-based learning and simulation by evaluating college-based stress, student perceptions on their competence and small group learning, and comparing stress and student perceptions level by grade point average. One group post-test only design was employed with a cohort of 185 second year nursing students who were enrolled in a seven-block integrated circulo-respiratory course with problem-based learning and simulation. Nursing students evaluated their stress as moderate with the academic subdomain as the highest stressor. The students reported favorable student perceptions on competence and small group learning. Nursing students view problem-based learning with simulations-based learning favorably irrespective of their course grade. The results of this study indicate that integration of problem-based learning with simulation should be considered for broader application in nursing education.

  20. Simulation Modeling by Classification of Problems: A Case of Cellular Manufacturing

    NASA Astrophysics Data System (ADS)

    Afiqah, K. N.; Mahayuddin, Z. R.

    2016-02-01

    Cellular manufacturing provides good solution approach to manufacturing area by applying Group Technology concept. The evolution of cellular manufacturing can enhance performance of the cell and to increase the quality of the product manufactured but it triggers other problem. Generally, this paper highlights factors and problems which emerge commonly in cellular manufacturing. The aim of the research is to develop a thorough understanding of common problems in cellular manufacturing. A part from that, in order to find a solution to the problems exist using simulation technique, this classification framework is very useful to be adapted during model building. Biology evolution tool was used in the research in order to classify the problems emerge. The result reveals 22 problems and 25 factors using cladistic technique. In this research, the expected result is the cladogram established based on the problems in cellular manufacturing gathered.

  1. Design and Application of Interactive Simulations in Problem-Solving in University-Level Physics Education

    NASA Astrophysics Data System (ADS)

    Ceberio, Mikel; Almudí, José Manuel; Franco, Ángel

    2016-08-01

    In recent years, interactive computer simulations have been progressively integrated in the teaching of the sciences and have contributed significant improvements in the teaching-learning process. Practicing problem-solving is a key factor in science and engineering education. The aim of this study was to design simulation-based problem-solving teaching materials and assess their effectiveness in improving students' ability to solve problems in university-level physics. Firstly, we analyze the effect of using simulation-based materials in the development of students' skills in employing procedures that are typically used in the scientific method of problem-solving. We found that a significant percentage of the experimental students used expert-type scientific procedures such as qualitative analysis of the problem, making hypotheses, and analysis of results. At the end of the course, only a minority of the students persisted with habits based solely on mathematical equations. Secondly, we compare the effectiveness in terms of problem-solving of the experimental group students with the students who are taught conventionally. We found that the implementation of the problem-solving strategy improved experimental students' results regarding obtaining a correct solution from the academic point of view, in standard textbook problems. Thirdly, we explore students' satisfaction with simulation-based problem-solving teaching materials and we found that the majority appear to be satisfied with the methodology proposed and took on a favorable attitude to learning problem-solving. The research was carried out among first-year Engineering Degree students.

  2. Carbon dioxide emissions from Tucuruí reservoir (Amazon biome): New findings based on three-dimensional ecological model simulations.

    PubMed

    Curtarelli, Marcelo Pedroso; Ogashawara, Igor; de Araújo, Carlos Alberto Sampaio; Lorenzzetti, João Antônio; Leão, Joaquim Antônio Dionísio; Alcântara, Enner; Stech, José Luiz

    2016-05-01

    We used a three-dimensional model to assess the dynamics of diffusive carbon dioxide flux (F(CO2)) from a hydroelectric reservoir located at Amazon rainforest. Our results showed that for the studied periods (2013 summer/wet and winter/dry seasons) the surface averaged F(CO2) presented similar behaviors, with regular emissions peaks. The mean daily surface averaged F(CO2) showed no significant difference between the seasons (p>0.01), with values around -1338mg Cm-2day-1 (summer/wet) and -1395mg Cm-2day-1 (winter/dry). At diel scale, the F(CO2) was large during the night and morning and low during the afternoon in both seasons. Regarding its spatial distribution, the F(CO2) showed to be more heterogeneous during the summer/wet than during the winter/dry season. The highest F(CO2) were observed at transition zone (-300mg Cm-2h-1) during summer and at littoral zone (-55mg Cm-2h-1) during the winter. The total CO2 emitted by the reservoir along 2013 year was estimated to be 1.1Tg C year-1. By extrapolating our results we found that the total carbon emitted by all Amazonian reservoirs can be around 7Tg C year-1, which is 22% lower than the previous published estimate. This significant difference should not be neglected in the carbon inventories since the carbon emission is a key factor when comparing the environmental impacts of different sources of electricity generation and can influences decision makers in the selection of the more appropriate source of electricity and, in case of hydroelectricity, the geographical position of the reservoirs.

  3. Counting solutions for the N -queens and Latin-square problems by Monte Carlo simulations.

    PubMed

    Zhang, Cheng; Ma, Jianpeng

    2009-01-01

    We apply Monte Carlo simulations to count the numbers of solutions of two well-known combinatorial problems: the N -queens problem and Latin-square problem. The original system is first converted to a general thermodynamic system, from which the number of solutions of the original system is obtained by using the method of computing the partition function. Collective moves are used to further accelerate sampling: swap moves are used in the N -queens problem and a cluster algorithm is developed for the Latin squares. The method can handle systems of 10;{4}degrees of freedom with more than 10;{10,000} solutions.

  4. Optimal Control Problem of Feeding Adaptations of Daphnia and Neural Network Simulation

    NASA Astrophysics Data System (ADS)

    Kmet', Tibor; Kmet'ov, Mria

    2010-09-01

    A neural network based optimal control synthesis is presented for solving optimal control problems with control and state constraints and open final time. The optimal control problem is transcribed into nonlinear programming problem, which is implemented with adaptive critic neural network [9] and recurrent neural network for solving nonlinear proprojection equations [10]. The proposed simulation methods is illustrated by the optimal control problem of feeding adaptation of filter feeders of Daphnia. Results show that adaptive critic based systematic approach and neural network solving of nonlinear equations hold promise for obtaining the optimal control with control and state constraints and open final time.

  5. How to solve complex problems in foundry plants - future of casting simulation -

    NASA Astrophysics Data System (ADS)

    Ohnaka, I.

    2015-06-01

    Although the computer simulation of casting has progressed dramatically over the last decades, there are still many challenges and problems. This paper discusses how to solve complex engineering problems in foundry plants and what we should do in the future, in particular, for casting simulation. First, problem solving procedures including application of computer simulation are demonstrated and various difficulties are pointed-out exemplifying mainly porosity defects in sand castings of spheroidal graphite cast irons. Next, looking back conventional scientific and engineering research to understand casting phenomena, challenges and problems are discussed from problem solving view point, followed by discussion on the issues we should challenge such as how to integrate huge amount of dispersed knowledge in various disciplines, differentiation of science-oriented and engineering-oriented models, professional ethics, how to handle fluctuating materials, initial and boundary conditions, error accumulation, simulation codes as black-box, etc. Finally some suggestions are made on how to challenge the issues such as promotion of research on the simulation based on the science- oriented model and publication of reliable data of casting phenomena in complicated-shaped castings including reconsideration of the evaluation system.

  6. Final Report for LDRD Project on Rapid Problem Setup for Mesh-Based Simulation (Rapsodi)

    SciTech Connect

    Brown, D L; Henshaw, W; Petersson, N A; Fast, P; Chand, K

    2003-02-07

    Under LLNL Exploratory Research LDRD funding, the Rapsodi project developed rapid setup technology for computational physics and engineering problems that require computational representations of complex geometry. Many simulation projects at LLNL involve the solution of partial differential equations in complex 3-D geometries. A significant bottleneck in carrying out these simulations arises in converting some specification of a geometry, such as a computer-aided design (CAD) drawing to a computationally appropriate 3-D mesh that can be used for simulation and analysis. Even using state-of-the-art mesh generation software, this problem setup step typically has required weeks or months, which is often much longer than required to carry out the computational simulation itself. The Rapsodi project built computational tools and designed algorithms that help to significantly reduce this setup time to less than a day for many realistic problems. The project targeted rapid setup technology for computational physics and engineering problems that use mixed-element unstructured meshes, overset meshes or Cartesian-embedded boundary (EB) meshes to represent complex geometry. It also built tools that aid in constructing computational representations of geometry for problems that do not require a mesh. While completely automatic mesh generation is extremely difficult, the amount of manual labor required can be significantly reduced. By developing novel, automated, component-based mesh construction procedures and automated CAD geometry repair and cleanup tools, Rapsodi has significantly reduced the amount of hand crafting required to generate geometry and meshes for scientific simulation codes.

  7. Path integral Monte Carlo simulation of global and local superfluidity in liquid 4He reservoirs separated by nanoscale apertures

    NASA Astrophysics Data System (ADS)

    Volkoff, Tyler; Kwon, Yongkyung; Whaley, K. Birgitta

    2016-10-01

    We present a path integral Monte Carlo study of the global superfluid fraction and local superfluid density in cylindrically symmetric reservoirs of liquid 4He separated by nanoaperture arrays. The superfluid response to both translations along the axis of symmetry (longitudinal response) and rotations about the cylinder axis (transverse response) are computed, together with radial and axial density distributions that reveal the microscopic inhomogeneity arising from the combined effects of the confining external potential and the 4He-4He interatomic potentials. We make a microscopic determination of the length scale of decay of superfluidity at the radial boundaries of the system by analyzing the local superfluid density distribution to extract a displacement length that quantifies the superfluid mass displacement away from the boundary. We find that the longitudinal superfluid response is reduced in reservoirs separated by a septum containing sufficiently small apertures compared to a cylinder with no intervening aperture array, for all temperatures below Tλ. For a single aperture in the septum, a significant drop in the longitudinal superfluid response is seen when the aperture diameter is made smaller than twice the empirical temperature-dependent 4He healing length, consistent with the formation of a weak link between the reservoirs. Increasing the diameter of a single aperture or the number of apertures in the array results in an increase of the superfluid density toward the expected bulk value.

  8. A hybrid simulation-optimization approach for solving the areal groundwater pollution source identification problems

    NASA Astrophysics Data System (ADS)

    Ayvaz, M. Tamer

    2016-07-01

    In this study, a new simulation-optimization approach is proposed for solving the areal groundwater pollution source identification problems which is an ill-posed inverse problem. In the simulation part of the proposed approach, groundwater flow and pollution transport processes are simulated by modeling the given aquifer system on MODFLOW and MT3DMS models. The developed simulation model is then integrated to a newly proposed hybrid optimization model where a binary genetic algorithm and a generalized reduced gradient method are mutually used. This is a novel approach and it is employed for the first time in the areal pollution source identification problems. The objective of the proposed hybrid optimization approach is to simultaneously identify the spatial distributions and input concentrations of the unknown areal groundwater pollution sources by using the limited number of pollution concentration time series at the monitoring well locations. The applicability of the proposed simulation-optimization approach is evaluated on a hypothetical aquifer model for different pollution source distributions. Furthermore, model performance is evaluated for measurement error conditions, different genetic algorithm parameter combinations, different numbers and locations of the monitoring wells, and different heterogeneous hydraulic conductivity fields. Identified results indicated that the proposed simulation-optimization approach may be an effective way to solve the areal groundwater pollution source identification problems.

  9. Numerical modeling of the simulated gas hydrate production test at Mallik 2L-38 in the pilot scale pressure reservoir LARS - Applying the "foamy oil" model

    NASA Astrophysics Data System (ADS)

    Abendroth, Sven; Thaler, Jan; Klump, Jens; Schicks, Judith; Uddin, Mafiz

    2014-05-01

    In the context of the German joint project SUGAR (Submarine Gas Hydrate Reservoirs: exploration, extraction and transport) we conducted a series of experiments in the LArge Reservoir Simulator (LARS) at the German Research Centre of Geosciences Potsdam. These experiments allow us to investigate the formation and dissociation of hydrates at large scale laboratory conditions. We performed an experiment similar to the field-test conditions of the production test in the Mallik gas hydrate field (Mallik 2L-38) in the Beaufort Mackenzie Delta of the Canadian Arctic. The aim of this experiment was to study the transport behavior of fluids in gas hydrate reservoirs during depressurization (see also Heeschen et al. and Priegnitz et al., this volume). The experimental results from LARS are used to provide details about processes inside the pressure vessel, to validate the models through history matching, and to feed back into the design of future experiments. In experiments in LARS the amount of methane produced from gas hydrates was much lower than expected. Previously published models predict a methane production rate higher than the one observed in experiments and field studies (Uddin et al. 2010; Wright et al. 2011). The authors of the aforementioned studies point out that the current modeling approach overestimates the gas production rate when modeling gas production by depressurization. They suggest that trapping of gas bubbles inside the porous medium is responsible for the reduced gas production rate. They point out that this behavior of multi-phase flow is not well explained by a "residual oil" model, but rather resembles a "foamy oil" model. Our study applies Uddin's (2010) "foamy oil" model and combines it with history matches of our experiments in LARS. Our results indicate a better agreement between experimental and model results when using the "foamy oil" model instead of conventional models of gas flow in water. References Uddin M., Wright J.F. and Coombe D

  10. Hybrid Simulated Annealing and Genetic Algorithms for Industrial Production Management Problems

    NASA Astrophysics Data System (ADS)

    Vasant, Pandian; Barsoum, Nader

    2009-08-01

    This paper describes the origin and significant contribution on the development of the Hybrid Simulated Annealing and Genetic Algorithms (HSAGA) approach for finding global optimization. HSAGA provide an insight approach to handle in solving complex optimization problems. The method is, the combination of meta-heuristic approaches of Simulated Annealing and novel Genetic Algorithms for solving a non-linear objective function with uncertain technical coefficients in an industrial production management problems. The proposed novel hybrid method is designed to search for global optimal for the non-linear objective function and search for the best feasible solutions of the decision variables. Simulated experiments were carried out rigorously to reflect the advantages of the proposed method. A description of the well developed method and the advanced computational experiment with MATLAB technical tool is presented. An industrial production management optimization problem is solved using HSAGA technique. The results are very much promising.

  11. Multi-Physics Demonstration Problem with the SHARP Reactor Simulation Toolkit

    SciTech Connect

    Merzari, E.; Shemon, E. R.; Yu, Y. Q.; Thomas, J. W.; Obabko, A.; Jain, Rajeev; Mahadevan, Vijay; Tautges, Timothy; Solberg, Jerome; Ferencz, Robert Mark; Whitesides, R.

    2015-12-21

    This report describes to employ SHARP to perform a first-of-a-kind analysis of the core radial expansion phenomenon in an SFR. This effort required significant advances in the framework Multi-Physics Demonstration Problem with the SHARP Reactor Simulation Toolkit used to drive the coupled simulations, manipulate the mesh in response to the deformation of the geometry, and generate the necessary modified mesh files. Furthermore, the model geometry is fairly complex, and consistent mesh generation for the three physics modules required significant effort. Fully-integrated simulations of a 7-assembly mini-core test problem have been performed, and the results are presented here. Physics models of a full-core model of the Advanced Burner Test Reactor have also been developed for each of the three physics modules. Standalone results of each of the three physics modules for the ABTR are presented here, which provides a demonstration of the feasibility of the fully-integrated simulation.

  12. On planetary motion—a way to solve the problem and a spreadsheet simulation

    NASA Astrophysics Data System (ADS)

    Benacka, Jan

    2014-07-01

    The article presents a way of solving the problem of planetary motion, or, the Kepler problem, without using the r\\to 1/r transition. The governing equation is solved for the components of the velocity vector in Cartesian coordinates. Substitution for speed in the law of energy conservation yields the equation of the trajectory. A time implicit closed formula for the azimuth is derived. An Excel application is presented that simulates the motion by solving the azimuth equation numerically without using programming.

  13. Application of a Two-Dimensional Reservoir Water-Quality Model of Beaver Lake, Arkansas, for the Evaluation of Simulated Changes in Input Water Quality, 2001-2003

    USGS Publications Warehouse

    Galloway, Joel M.; Green, W. Reed

    2007-01-01

    L3 and L4 and the least increase occurred at sites L2 and L5 when calibrated daily input phosphorus concentrations were increased. When orthophosphorus was increased in all three tributaries simultaneously by a factor of 10, daily mean orthophosphorus concentrations in the epilimnion of the reservoir were almost 11 times greater than the calibrated concentrations at sites L2 and L5, and 15 times greater in the epilimnion of the reservoir at sites L3 and L4. Phosphorus concentrations in Beaver Lake increased less when nitrogen and phosphorus were increased simultaneously than when phosphorus was increased independently. The greatest simulated increase in algal biomass (represented as chlorophyll a) occurred when nitrogen and phosphorus were increased simultaneously in the three main tributaries. On average, the chlorophyll a values only increased less than 1 microgram per liter when concentrations of nitrogen or phosphorous were increased independently by a factor of 10 at all three tributaries. In comparison, when nitrogen and phosphorus were increased simultaneously by a factor of 10 for all three tributaries, the chlorophyll a concentration increased by about 10 micrograms per liter on average, with a maximum increase of about 57 micrograms per liter in the epilimnion at site L3 in Beaver Lake. Changes in algal biomass with changes in input nitrogen and phosphorus were variable through time in the Beaver Lake model from April 2001 to April 2003. When calibrated daily input nitrogen and phosphorus concentrations were increased simultaneously for the three main tributaries, the increase in chlorophyll a concentration was the greatest in late spring and summer of 2002. Changes in calibrated daily input inorganic suspended solids concentrations were examined because of the effect they may have on water clarity in Beaver Lake. The increase in total suspended solids was greatest in the hypolimnion at the upstream end of Beaver Lake, and negligible changes

  14. Carbonate petroleum reservoirs

    SciTech Connect

    Roehl, P.O.; Choquette, P.W.

    1985-01-01

    This book presents papers on the geology of petroleum deposits. Topics considered include diagenesis, porosity, dolomite reservoirs, deposition, reservoir rock, reefs, morphology, fracture-controlled production, Cenozoic reservoirs, Mesozoic reservoirs, and Paleozoic reservoirs.

  15. Assessing problem-solving skills in construction education with the virtual construction simulator

    NASA Astrophysics Data System (ADS)

    Castronovo, Fadi

    The ability to solve complex problems is an essential skill that a construction and project manager must possess when entering the architectural, engineering, and construction industry. Such ability requires a mixture of problem-solving skills, ranging from lower to higher order thinking skills, composed of cognitive and metacognitive processes. These skills include the ability to develop and evaluate construction plans and manage the execution of such plans. However, in a typical construction program, introducing students to such complex problems can be a challenge, and most commonly the learner is presented with only part of a complex problem. To support this challenge, the traditional methodology of delivering design, engineering, and construction instruction has been going through a technological revolution, due to the rise of computer-based technology. For example, in construction classrooms, and other disciplines, simulations and educational games are being utilized to support the development of problem-solving skills. Previous engineering education research has illustrated the high potential that simulations and educational games have in engaging in lower and higher order thinking skills. Such research illustrated their capacity to support the development of problem-solving skills. This research presents evidence supporting the theory that educational simulation games can help with the learning and retention of transferable problem-solving skills, which are necessary to solve complex construction problems. The educational simulation game employed in this study is the Virtual Construction Simulator (VCS). The VCS is a game developed to provide students in an engaging learning activity that simulates the planning and managing phases of a construction project. Assessment of the third iteration of the VCS(3) game has shown pedagogical value in promoting students' motivation and a basic understanding of construction concepts. To further evaluate the benefits on

  16. Simulation of Runoff and Reservoir Inflow for Use in a Flood-Analysis Model for the Delaware River, Pennsylvania, New Jersey, and New York, 2004-2006

    USGS Publications Warehouse

    Goode, Daniel J.; Koerkle, Edward H.; Hoffman, Scott A.; Regan, R. Steve; Hay, Lauren E.; Markstrom, Steven L.

    2010-01-01

    A model was developed to simulate inflow to reservoirs and watershed runoff to streams during three high-flow events between September 2004 and June 2006 for the main-stem subbasin of the Delaware River draining to Trenton, N.J. The model software is a modified version of the U.S. Geological Survey (USGS) Precipitation-Runoff Modeling System (PRMS), a modular, physically based, distributed-parameter modeling system developed to evaluate the impacts of various combinations of precipitation, climate, and land use on surface-water runoff and general basin hydrology. The PRMS model simulates time periods associated with main-stem flooding that occurred in September 2004, April 2005, and June 2006 and uses both daily and hourly time steps. Output from the PRMS model was formatted for use as inflows to a separately documented reservoir and riverrouting model, the HEC-ResSim model, developed by the U.S. Army Corps of Engineers Hydrologic Engineering Center to evaluate flooding. The models were integrated through a graphical user interface. The study area is the 6,780 square-mile watershed of the Delaware River in the states of Pennsylvania, New Jersey, and New York that drains to Trenton, N.J. A geospatial database was created for use with a geographic information system to assist model discretization, determine land-surface characterization, and estimate model parameters. The USGS National Elevation Dataset at 100-meter resolution, a Digital Elevation Model (DEM), was used for model discretization into streams and hydrologic response units. In addition, geospatial processing was used to estimate initial model parameters from the DEM and other data layers, including land use. The model discretization represents the study area using 869 hydrologic response units and 452 stream segments. The model climate data for point stations were obtained from multiple sources. These sources included daily data for 22 National Weather Service (NWS) Cooperative Climate Station network

  17. Geomechanical simulation of the stress tensor rotation caused by injection of cold water in a deep geothermal reservoir

    NASA Astrophysics Data System (ADS)

    Jeanne, Pierre; Rutqvist, Jonny; Dobson, Patrick F.; Garcia, Julio; Walters, Mark; Hartline, Craig; Borgia, Andrea

    2015-12-01

    We present a three-dimensional thermohydromechanical numerical study of the evolution and distribution of the stress tensor within the northwest part of The Geysers geothermal reservoir (in California), including a detailed study of the region around one injection well from 2003 to 2012. Initially, after imposing a normal faulting stress regime, we calculated local changes in the stress regime around injection wells. Our results were compared with previously published studies in which the stress state was inferred from inverting the focal plane mechanism of seismic events. Our main finding is that changes in stress tensor orientation are caused by injection-induced progressive cooling of the reservoir, as well as by the seasonal variations in injection rate. Because of the gravity flow and cooling around a liquid zone formed by the injection, the vertical stress reduction is larger and propagates far below the injection well. At the same time, the horizontal stress increases, mostly because of stress redistribution below and above the cooling area. These two phenomena cause the rotation of the stress tensor and the appearance of a strike-slip regime above, inside, and below the cooling area. The cooling and the associated rotation of the stress regime can play a significant role in the observed long-term deepening of the microseismicity below active injection wells.

  18. Effects of selective withdrawal on hydrodynamics and water quality of a thermally stratified reservoir in the southern side of the Mediterranean Sea: a simulation approach.

    PubMed

    Zouabi-Aloui, Besma; Adelana, Segun Michael; Gueddari, Moncef

    2015-05-01

    This study uses a multidisciplinary approach to simulate the spatial and temporal patterns of hydrodynamics and water quality in a thermally stratified reservoir in the southern side of the Mediterranean Sea in response to water withdrawal elevation using the 2D water quality and laterally averaged hydrodynamic model CE-QUAL-W2. The withdrawal elevation controls largely the transfer of heat and constituents in the dam in particular during thermal stratification. Fifteen scenarios of withdrawal elevation are possible. To identify the most effective scenarios, a hierarchical clustering technique was performed and only four scenarios were clustered. Deep withdrawals deepen the hypoxia, increase the thickness of the metalimnion, and weaken the stratification stability, which facilitate the vertical transfer of heat and dissolved oxygen mainly. Surface withdrawals, however, shrink the metalimnion and tend to strengthen the stratification, resulting in less transfer of matter from the epilimnion to the hypolimnion. Most of the bottom sediment is overlaid by the hypolimnion. The oxygen depletes significantly and waters become anoxic at a few meters depth. For all scenarios, the reservoir experiences a summer hypolimnetic anoxia, which lasts from 42 to 80 days and seems to decrease as withdrawal elevation increases. At the end of stratification, waters below the withdrawal elevation showed a noticeable release of iron, nutrients, and suspended sediments that increases with depth and near-bottom turbulence. Attention should be drawn to shallower withdrawals because they accumulate nutrients and silts continuously in the reservoir, which may deteriorate water quality. Based on these results, a withdrawal elevation rule is presented. This rule may be adjusted to optimize water withdrawal elevation for dams in the region with similar geometry.

  19. Performance and complementarity of two systemic models (reservoir and neural networks) used to simulate spring discharge and piezometry for a karst aquifer

    NASA Astrophysics Data System (ADS)

    Kong-A-Siou, Line; Fleury, Perrine; Johannet, Anne; Borrell Estupina, Valérie; Pistre, Séverin; Dörfliger, Nathalie

    2014-11-01

    Karst aquifers can provide previously untapped freshwater resources and have thus generated considerable interest among stakeholders involved in the water supply sector. Here we compare the capacity of two systemic models to simulate the discharge and piezometry of a karst aquifer. Systemic models have the advantage of allowing the study of heterogeneous, complex karst systems without relying on extensive geographical and meteorological datasets. The effectiveness and complementarity of the two models are evaluated for a range of hydrologic conditions and for three methods to estimate evapotranspiration (Monteith, a priori ET, and effective rainfall). The first model is a reservoir model (referred to as VENSIM, after the software used), which is designed with just one reservoir so as to be as parsimonious as possible. The second model is a neural network (NN) model. The models are designed to simulate the rainfall-runoff and rainfall-water level relations in a karst conduit. The Lez aquifer, a karst aquifer located near the city of Montpellier in southern France and a critical water resource, was chosen to compare the two models. Simulated discharge and water level were compared after completing model design and calibration. The results suggest that the NN model is more effective at incorporating the nonlinearity of the karst spring for extreme events (extreme low and high water levels), whereas VENSIM provides a better representation of intermediate-amplitude water level fluctuations. VENSIM is sensitive to the method used to estimate evapotranspiration, whereas the NN model is not. Given that the NN model performs better for extreme events, it is better for operational applications (predicting floods or determining water pumping height). VENSIM, on the other hand, seems more appropriate for representing the hydrologic state of the basin during intermediate periods, when several effects are at work: rain, evapotranspiration, development of vegetation, etc. A

  20. Late-stage magma flow in a shallow felsic reservoir: Merging the anisotropy of magnetic susceptibility record with numerical simulations in La Gloria Pluton, central Chile

    NASA Astrophysics Data System (ADS)

    GutiéRrez, F.; PayacáN, I.; Gelman, S. E.; Bachmann, O.; Parada, M. A.

    2013-05-01

    La Gloria Pluton is a 10 Myr old epizonal intrusion located in the southern Andes. We present anisotropy of magnetic susceptibility data that indicate a magnetic fabric that is mainly oblate. We find that lineations are weak and have a N-NW trend with a nearly horizontal dip, while foliations are more pronounced, have NW trends, and have dips that vary from vertical at the walls of the intrusion to horizontal at the center and under the roof of the chamber. To interpret these magmatic fabrics, we developed a time-dependent 2-D magmatic fluid dynamic numerical simulation. Our model is calibrated with MELTS and accounts for the coupled processes of cooling, crystallization, and degassing of a magma chamber. Simulations indicate that the resulting convective flow pattern in the crystallizing reservoir is consistent with the magnetic fabric, which is largely produced in the shear zone between the convecting liquid-dominated core and the growing solidification fronts adjacent to the walls. The magnetic fabric records the last increment of strain induced by convective magmatic flow in the cooling reservoir during crystallization at the rheological magma locking point along solidification fronts. Despite the small size of the pluton, the core of the chamber remains thermally insulated from the colder host rocks, surviving up to 20 kyr above the solidus, which allows enough time for the extraction of residual leucogranitic melt and partial late magmatic reactive recrystallization. The results of the simulations are also consistent with the previously determined compositional and mineralogical zonation patterns in the pluton.

  1. Tenth workshop on geothermal reservoir engineering: proceedings

    SciTech Connect

    Not Available

    1985-01-22

    The workshop contains presentations in the following areas: (1) reservoir engineering research; (2) field development; (3) vapor-dominated systems; (4) the Geysers thermal area; (5) well test analysis; (6) production engineering; (7) reservoir evaluation; (8) geochemistry and injection; (9) numerical simulation; and (10) reservoir physics. (ACR)

  2. Examining the Accuracy of Astrophysical Disk Simulations with a Generalized Hydrodynamical Test Problem

    NASA Astrophysics Data System (ADS)

    Raskin, Cody; Owen, J. Michael

    2016-11-01

    We discuss a generalization of the classic Keplerian disk test problem allowing for both pressure and rotational support, as a method of testing astrophysical codes incorporating both gravitation and hydrodynamics. We argue for the inclusion of pressure in rotating disk simulations on the grounds that realistic, astrophysical disks exhibit non-negligible pressure support. We then apply this test problem to examine the performance of various smoothed particle hydrodynamics (SPH) methods incorporating a number of improvements proposed over the years to address problems noted in modeling the classical gravitation-only Keplerian disk. We also apply this test to a newly developed extension of SPH based on reproducing kernels called CRKSPH. Counterintuitively, we find that pressure support worsens the performance of traditional SPH on this problem, causing unphysical collapse away from the steady-state disk solution even more rapidly than the purely gravitational problem, whereas CRKSPH greatly reduces this error.

  3. Majorana Positivity and the Fermion Sign Problem of Quantum Monte Carlo Simulations.

    PubMed

    Wei, Z C; Wu, Congjun; Li, Yi; Zhang, Shiwei; Xiang, T

    2016-06-24

    The sign problem is a major obstacle in quantum Monte Carlo simulations for many-body fermion systems. We examine this problem with a new perspective based on the Majorana reflection positivity and Majorana Kramers positivity. Two sufficient conditions are proven for the absence of the fermion sign problem. Our proof provides a unified description for all the interacting lattice fermion models previously known to be free of the sign problem based on the auxiliary field quantum Monte Carlo method. It also allows us to identify a number of new sign-problem-free interacting fermion models including, but not limited to, lattice fermion models with repulsive interactions but without particle-hole symmetry, and interacting topological insulators with spin-flip terms.

  4. The Use of a Real Life Simulated Problem Based Learning Activity in a Corporate Environment

    ERIC Educational Resources Information Center

    Laurent, Mark A.

    2013-01-01

    This narrative study examines using a real life simulated problem base learning activity during education of clinical staff, which is expected to design and develop clinically correct electronic charting systems. Expertise in healthcare does not readily transcend to the realm of manipulating software to collect patient data that is pertinent to…

  5. Teaching clinical reasoning and problem-solving skills using human patient simulation.

    PubMed

    Vyas, Deepti; Ottis, Erica J; Caligiuri, Frank J

    2011-11-10

    This paper discusses using human patient simulation (HPS) to expose students to complex dynamic patient cases that require clinical judgment, problem-solving skills, and teamwork skills for success. An example of an HPS exercise used to teach multifaceted clinical concepts in a therapeutics course also is provided.

  6. Factors Affecting Perceived Learning of Engineering Students in Problem Based Learning Supported by Business Simulation

    ERIC Educational Resources Information Center

    Chaparro-Pelaez, Julian; Iglesias-Pradas, Santiago; Pascual-Miguel, Felix J.; Hernandez-Garcia, Angel

    2013-01-01

    Although literature about problem based learning (PBL) is not scarce, there is little research on experiences about learning methodologies that combine PBL and the use of simulation tools. This lack of studies is even more notable in the case of engineering courses. The motivation for this study is to show how such a combination of PBL and…

  7. MFIX simulation of NETL/PSRI challenge problem of circulating fluidized bed

    DOE PAGES

    Li, Tingwen; Dietiker, Jean-François; Shahnam, Mehrdad

    2012-12-01

    In this paper, numerical simulations of NETL/PSRI challenge problem of circulating fluidized bed (CFB) using the open-source code Multiphase Flow with Interphase eXchange (MFIX) are reported. Two rounds of simulation results are reported including the first-round blind test and the second-round modeling refinement. Three-dimensional high fidelity simulations are conducted to model a 12-inch diameter pilot-scale CFB riser. Detailed comparisons between numerical results and experimental data are made with respect to axial pressure gradient profile, radial profiles of solids velocity and solids mass flux along different radial directions at various elevations for operating conditions covering different fluidization regimes. Overall, the numericalmore » results show that CFD can predict the complex gas–solids flow behavior in the CFB riser reasonably well. In addition, lessons learnt from modeling this challenge problem are presented.« less

  8. Partitioned semi-implicit methods for simulation of biomechanical fluid-structure interaction problems

    NASA Astrophysics Data System (ADS)

    Naseri, A.; Lehmkuhl, O.; Gonzalez, I.; Oliva, A.

    2016-09-01

    This paper represents numerical simulation of fluid-structure interaction (FSI) system involving an incompressible viscous fluid and a lightweight elastic structure. We follow a semi-implicit approach in which we implicitly couple the added-mass term (pressure stress) of the fluid to the structure, while other terms are coupled explicitly. This significantly reduces the computational cost of the simulations while showing adequate stability. Several coupling schemes are tested including fixed-point method with different static and dynamic relaxation, as well as Newton-Krylov method with approximated Jacobian. Numerical tests are conducted in the context of a biomechanical problem. Results indicate that the Newton-Krylov solver outperforms fixed point ones while introducing more complexity to the problem due to the evaluation of the Jacobian. Fixed-point solver with Aitken's relaxation method also proved to be a simple, yet efficient method for FSI simulations.

  9. Composing Problem Solvers for Simulation Experimentation: A Case Study on Steady State Estimation

    PubMed Central

    Leye, Stefan; Ewald, Roland; Uhrmacher, Adelinde M.

    2014-01-01

    Simulation experiments involve various sub-tasks, e.g., parameter optimization, simulation execution, or output data analysis. Many algorithms can be applied to such tasks, but their performance depends on the given problem. Steady state estimation in systems biology is a typical example for this: several estimators have been proposed, each with its own (dis-)advantages. Experimenters, therefore, must choose from the available options, even though they may not be aware of the consequences. To support those users, we propose a general scheme to aggregate such algorithms to so-called synthetic problem solvers, which exploit algorithm differences to improve overall performance. Our approach subsumes various aggregation mechanisms, supports automatic configuration from training data (e.g., via ensemble learning or portfolio selection), and extends the plugin system of the open source modeling and simulation framework James II. We show the benefits of our approach by applying it to steady state estimation for cell-biological models. PMID:24705453

  10. A proposed simulation optimization model framework for emergency department problems in public hospital

    NASA Astrophysics Data System (ADS)

    Ibrahim, Ireen Munira; Liong, Choong-Yeun; Bakar, Sakhinah Abu; Ahmad, Norazura; Najmuddin, Ahmad Farid

    2015-12-01

    The Emergency Department (ED) is a very complex system with limited resources to support increase in demand. ED services are considered as good quality if they can meet the patient's expectation. Long waiting times and length of stay is always the main problem faced by the management. The management of ED should give greater emphasis on their capacity of resources in order to increase the quality of services, which conforms to patient satisfaction. This paper is a review of work in progress of a study being conducted in a government hospital in Selangor, Malaysia. This paper proposed a simulation optimization model framework which is used to study ED operations and problems as well as to find an optimal solution to the problems. The integration of simulation and optimization is hoped can assist management in decision making process regarding their resource capacity planning in order to improve current and future ED operations.

  11. Potential Impacts of Leakage from Black Rock Reservoir on the Hanford Site Unconfined Aquifer: Initial Hypothetical Simulations of Flow and Contaminant Transport

    SciTech Connect

    Freedman, Vicky L.

    2007-03-09

    Initial scoping calculations of the unconfined aquifer at the Hanford Site were carried out for the U.S. Bureau of Reclamation (USBR) to investi¬gate the potential impacts on the Hanford unconfined aquifer that would result from leakage from the proposed Black Rock Reservoir to the west. Although impacts on groundwater flow and contaminant transport were quantified based on numerical simulation results, the investigation represented a quali¬tative assessment of the potential lateral recharge that could result in adverse effects on the aquifer. Because the magnitude of the potential leakage is unknown, hypothetical bounding calculations were performed. When a quantitative analysis of the magnitude of the potential recharge from Black Rock Reservoir is obtained, the hydrologic impacts analysis will be revisited. The analysis presented in this report represent initial bounding calculations. A maximum lateral recharge (i.e., upland flux) was determined in the first part of this study by executing steady-state flow simulations that raised the water table no higher than the elevation attained in the Central Plateau during the Hanford operational period. This metric was selected because it assumed a maximum remobilization of contaminants that existed under previous fully saturated conditions. Three steady-state flow fields were then used to analyze impacts to transient contaminant transport: a maximum recharge (27,000 acre-ft/yr), a no additional flux (365 acre-ft/yr), and an intermediate recharge case (16,000 acre-ft/yr). The transport behavior of four radionuclides was assessed for a 300 year simula¬tion period with the three flow fields. The four radionuclides are current contaminants of concern (COCs) in the Central Plateau and include tritium, iodine-129, technetium-99, and uranium-238. Transient flow and transport simulations were used to establish hypothetical concentration distributions in the subsurface. Using the simulated concentration distributions in 2005

  12. Numerical simulation of dam-break problem using staggered finite volume method

    NASA Astrophysics Data System (ADS)

    Budiasih, L. K.; Wiryanto, L. H.

    2016-02-01

    A problem in a dam-break is when a wall separating two sides of water is removed. A shock wave occurs and propagates. The behavior of the wave is interesting to be investigated with respect to the water depth and its wave speed. The aim of this research is to model dam-break problem using the non-linear shallow water equations and solve them numerically using staggered finite volume method. The solution is used to simulate the dam-break on a wet bed. Our numerical solution will be compared to the analytical solution of shallow water equations for dam-break problem. The momentum non-conservative finite volume scheme on a staggered grid will give a good agreement for dam-break problem on a wet bed, for depth ratios greater than 0.25.

  13. Feature Extraction from Simulations and Experiments: Preliminary Results Using a Fluid Mix Problem

    SciTech Connect

    Kamath, C; Nguyen, T

    2005-01-04

    Code validation, or comparing the output of computer simulations to experiments, is necessary to determine which simulation is a better approximation to an experiment. It can also be used to determine how the input parameters in a simulation can be modified to yield output that is closer to the experiment. In this report, we discuss our experiences in the use of image processing techniques for extracting features from 2-D simulations and experiments. These features can be used in comparing the output of simulations to experiments, or to other simulations. We first describe the problem domain and the data. We next explain the need for cleaning or denoising the experimental data and discuss the performance of different techniques. Finally, we discuss the features of interest and describe how they can be extracted from the data. The focus in this report is on extracting features from experimental and simulation data for the purpose of code validation; the actual interpretation of these features and their use in code validation is left to the domain experts.

  14. Parallel Simulation of Three-Dimensional Free Surface Fluid Flow Problems

    SciTech Connect

    BAER,THOMAS A.; SACKINGER,PHILIP A.; SUBIA,SAMUEL R.

    1999-10-14

    Simulation of viscous three-dimensional fluid flow typically involves a large number of unknowns. When free surfaces are included, the number of unknowns increases dramatically. Consequently, this class of problem is an obvious application of parallel high performance computing. We describe parallel computation of viscous, incompressible, free surface, Newtonian fluid flow problems that include dynamic contact fines. The Galerkin finite element method was used to discretize the fully-coupled governing conservation equations and a ''pseudo-solid'' mesh mapping approach was used to determine the shape of the free surface. In this approach, the finite element mesh is allowed to deform to satisfy quasi-static solid mechanics equations subject to geometric or kinematic constraints on the boundaries. As a result, nodal displacements must be included in the set of unknowns. Other issues discussed are the proper constraints appearing along the dynamic contact line in three dimensions. Issues affecting efficient parallel simulations include problem decomposition to equally distribute computational work among a SPMD computer and determination of robust, scalable preconditioners for the distributed matrix systems that must be solved. Solution continuation strategies important for serial simulations have an enhanced relevance in a parallel coquting environment due to the difficulty of solving large scale systems. Parallel computations will be demonstrated on an example taken from the coating flow industry: flow in the vicinity of a slot coater edge. This is a three dimensional free surface problem possessing a contact line that advances at the web speed in one region but transitions to static behavior in another region. As such, a significant fraction of the computational time is devoted to processing boundary data. Discussion focuses on parallel speed ups for fixed problem size, a class of problems of immediate practical importance.

  15. Developing and Managing a Comprehensive Reservoir Analysis Model

    DTIC Science & Technology

    1988-11-01

    a flood control only, single event reservoir simulation model to a generalized hydrologic and economic reservoir simulation model with capabilities...The first release of HEC-5, May 1973, gave the Corps of Engineers a mainframe based, reservoir simulation model which automated the traditional manual

  16. Solving complex maintenance planning optimization problems using stochastic simulation and multi-criteria fuzzy decision making

    SciTech Connect

    Tahvili, Sahar; Österberg, Jonas; Silvestrov, Sergei; Biteus, Jonas

    2014-12-10

    One of the most important factors in the operations of many cooperations today is to maximize profit and one important tool to that effect is the optimization of maintenance activities. Maintenance activities is at the largest level divided into two major areas, corrective maintenance (CM) and preventive maintenance (PM). When optimizing maintenance activities, by a maintenance plan or policy, we seek to find the best activities to perform at each point in time, be it PM or CM. We explore the use of stochastic simulation, genetic algorithms and other tools for solving complex maintenance planning optimization problems in terms of a suggested framework model based on discrete event simulation.

  17. Coupled electromagnetic-thermodynamic simulations of microwave heating problems using the FDTD algorithm.

    PubMed

    Kopyt, Paweł; Celuch, Małgorzata

    2007-01-01

    A practical implementation of a hybrid simulation system capable of modeling coupled electromagnetic-thermodynamic problems typical in microwave heating is described. The paper presents two approaches to modeling such problems. Both are based on an FDTD-based commercial electromagnetic solver coupled to an external thermodynamic analysis tool required for calculations of heat diffusion. The first approach utilizes a simple FDTD-based thermal solver while in the second it is replaced by a universal commercial CFD solver. The accuracy of the two modeling systems is verified against the original experimental data as well as the measurement results available in literature.

  18. HEAP: Heat Energy Analysis Program, a computer model simulating solar receivers. [solving the heat transfer problem

    NASA Technical Reports Server (NTRS)

    Lansing, F. L.

    1979-01-01

    A computer program which can distinguish between different receiver designs, and predict transient performance under variable solar flux, or ambient temperatures, etc. has a basic structure that fits a general heat transfer problem, but with specific features that are custom-made for solar receivers. The code is written in MBASIC computer language. The methodology followed in solving the heat transfer problem is explained. A program flow chart, an explanation of input and output tables, and an example of the simulation of a cavity-type solar receiver are included.

  19. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface ground water: background, base cases, shallow reservoirs, short-term gas and water transport

    EPA Pesticide Factsheets

    Researchers examined gas and water transport between a deep tight shale gas reservoir and a shallow overlying aquifer in the two years following hydraulic fracturing, assuming a pre-existing connecting pathway.

  20. Parallel computations using a cluster of workstations to simulate elasticity problems

    NASA Astrophysics Data System (ADS)

    Darmawan, J. B. B.; Mungkasi, S.

    2016-11-01

    Computational physics has played important roles in real world problems. This paper is within the applied computational physics area. The aim of this study is to observe the performance of parallel computations using a cluster of workstations (COW) to simulate elasticity problems. Parallel computations with the COW configuration are conducted using the Message Passing Interface (MPI) standard. In parallel computations with COW, we consider five scenarios with twenty simulations. In addition to the execution time, efficiency is used to evaluate programming algorithm scenarios. Sequential and parallel programming performances are evaluated based on their execution time and efficiency. Results show that the one-dimensional elasticity equations are not appropriate to be solved in parallel with MPI_Send and MPI_Recv technique in the MPI standard, because the total amount of time to exchange data is considered more dominant compared with the total amount of time to conduct the basic elasticity computation.

  1. Simulator test to study hot-flow problems related to a gas cooled reactor

    NASA Technical Reports Server (NTRS)

    Poole, J. W.; Freeman, M. P.; Doak, K. W.; Thorpe, M. L.

    1973-01-01

    An advance study of materials, fuel injection, and hot flow problems related to the gas core nuclear rocket is reported. The first task was to test a previously constructed induction heated plasma GCNR simulator above 300 kW. A number of tests are reported operating in the range of 300 kW at 10,000 cps. A second simulator was designed but not constructed for cold-hot visualization studies using louvered walls. A third task was a paper investigation of practical uranium feed systems, including a detailed discussion of related problems. The last assignment resulted in two designs for plasma nozzle test devices that could be operated at 200 atm on hydrogen.

  2. A procedure for automating CFD simulations of an inlet-bleed problem

    NASA Astrophysics Data System (ADS)

    Chyu, Wei J.; Rimlinger, Mark J.; Shih, Tom I.-P.

    1995-03-01

    A procedure was developed to improve the turn-around time for computational fluid dynamics (CFD) simulations of an inlet-bleed problem involving oblique shock-wave/boundary-layer interactions on a flat plate with bleed into a plenum through one or more circular holes. This procedure is embodied in a preprocessor called AUTOMAT. With AUTOMAT, once data for the geometry and flow conditions have been specified (either interactively or via a namelist), it will automatically generate all input files needed to perform a three-dimensional Navier-Stokes simulation of the prescribed inlet-bleed problem by using the PEGASUS and OVERFLOW codes. The input files automatically generated by AUTOMAT include those for the grid system and those for the initial and boundary conditions. The grid systems automatically generated by AUTOMAT are multi-block structured grids of the overlapping type. Results obtained by using AUTOMAT are presented to illustrate its capability.

  3. Solution of the nonlinear inverse scattering problem by T -matrix completion. II. Simulations

    NASA Astrophysics Data System (ADS)

    Levinson, Howard W.; Markel, Vadim A.

    2016-10-01

    This is Part II of the paper series on data-compatible T -matrix completion (DCTMC), which is a method for solving nonlinear inverse problems. Part I of the series [H. W. Levinson and V. A. Markel, Phys. Rev. E 94, 043317 (2016), 10.1103/PhysRevE.94.043317] contains theory and here we present simulations for inverse scattering of scalar waves. The underlying mathematical model is the scalar wave equation and the object function that is reconstructed is the medium susceptibility. The simulations are relevant to ultrasound tomographic imaging and seismic tomography. It is shown that DCTMC is a viable method for solving strongly nonlinear inverse problems with large data sets. It provides not only the overall shape of the object, but the quantitative contrast, which can correspond, for instance, to the variable speed of sound in the imaged medium.

  4. Potential Impacts of Leakage from Black Rock Reservoir on the Hanford Site Unconfined Aquifer: Initial Hypothetical Simulations of Flow and Contaminant Transport

    SciTech Connect

    Freedman, Vicky L.

    2008-01-30

    Initial scoping calculations of the unconfined aquifer at the Hanford Site were carried out for the U.S. Bureau of Reclamation (USBR) to investigate the potential impacts on the Hanford unconfined aquifer that would result from leakage from the proposed Black Rock Reservoir to the west. Although impacts on groundwater flow and contaminant transport were quantified based on numerical simulation results, the investigation represented a qualitative assessment of the potential lateral recharge that could result in adverse effects on the aquifer. Because the magnitude of the potential leakage is unknown, hypothetical bounding calculations were performed. When a quantitative analysis of the magnitude of the potential recharge from Black Rock Reservoir is obtained, the hydrologic impacts analysis will be revisited. The analysis presented in this report represents initial bounding calculations. A maximum lateral recharge (i.e., upland flux) was determined in the first part of this study by executing steady-state flow simulations that raised the water table no higher than the elevation attained in the Central Plateau during the Hanford operational period. This metric was selected because it assumed a maximum remobilization of contaminants that existed under previous fully saturated conditions. Three steady-state flow fields were then used to analyze impacts to transient contaminant transport: a maximum recharge (27,000 acre-ft/yr), a no additional flux (365 acre-ft/yr), and an intermediate recharge case (16,000 acre-ft/yr). The transport behavior of four radionuclides was assessed for a 300 year simulation period with the three flow fields. The four radionuclides are tritium, iodine-129, technetium-99, and uranium-238. Transient flow and transport simulations were used to establish hypothetical concentration distributions in the subsurface. Using the simulated concentration distributions in 2005 as initial conditions for steady-state flow runs, simulations were executed to

  5. Dynamics of corrosion rates associated with nitrite or nitrate mediated control of souring under biological conditions simulating an oil reservoir.

    PubMed

    Rempel, C L; Evitts, R W; Nemati, M

    2006-10-01

    Representative microbial cultures from an oil reservoir and electrochemical techniques including potentiodynamic scan and linear polarization were used to investigate the time dependent corrosion rate associated with control of biogenic sulphide production through addition of nitrite, nitrate and a combination of nitrate-reducing, sulphide-oxidizing bacteria (NR-SOB) and nitrate. The addition of nitrate alone did not prevent the biogenic production of sulphide but the produced sulphide was eventually oxidized and removed from the system. The addition of nitrate and NR-SOB had a similar effect on oxidation and removal of sulphide present in the system. However, as the addition of nitrate and NR-SOB was performed towards the end of sulphide production phase, the assessment of immediate impact was not possible. The addition of nitrite inhibited the biogenic production of sulphide immediately and led to removal of sulphide through nitrite mediated chemical oxidation of sulphide. The real time corrosion rate measurement revealed that in all three cases an acceleration in the corrosion rate occurred during the oxidation and removal of sulphide. Amendments of nitrate and NR-SOB or nitrate alone both gave rise to localized corrosion in the form of pits, with the maximum observed corrosion rates of 0.72 and 1.4 mm year(-1), respectively. The addition of nitrite also accelerated the corrosion rate but the maximum corrosion rate observed following nitrite addition was 0.3 mm year(-1). Furthermore, in the presence of nitrite the extent of pitting was not as high as those observed with other control methods.

  6. Solving iTOUGH2 simulation and optimization problems using the PEST protocol

    SciTech Connect

    Finsterle, S.A.; Zhang, Y.

    2011-02-01

    The PEST protocol has been implemented into the iTOUGH2 code, allowing the user to link any simulation program (with ASCII-based inputs and outputs) to iTOUGH2's sensitivity analysis, inverse modeling, and uncertainty quantification capabilities. These application models can be pre- or post-processors of the TOUGH2 non-isothermal multiphase flow and transport simulator, or programs that are unrelated to the TOUGH suite of codes. PEST-style template and instruction files are used, respectively, to pass input parameters updated by the iTOUGH2 optimization routines to the model, and to retrieve the model-calculated values that correspond to observable variables. We summarize the iTOUGH2 capabilities and demonstrate the flexibility added by the PEST protocol for the solution of a variety of simulation-optimization problems. In particular, the combination of loosely coupled and tightly integrated simulation and optimization routines provides both the flexibility and control needed to solve challenging inversion problems for the analysis of multiphase subsurface flow and transport systems.

  7. A linked simulation-optimization model for solving the unknown groundwater pollution source identification problems.

    PubMed

    Ayvaz, M Tamer

    2010-09-20

    This study proposes a linked simulation-optimization model for solving the unknown groundwater pollution source identification problems. In the proposed model, MODFLOW and MT3DMS packages are used to simulate the flow and transport processes in the groundwater system. These models are then integrated with an optimization model which is based on the heuristic harmony search (HS) algorithm. In the proposed simulation-optimization model, the locations and release histories of the pollution sources are treated as the explicit decision variables and determined through the optimization model. Also, an implicit solution procedure is proposed to determine the optimum number of pollution sources which is an advantage of this model. The performance of the proposed model is evaluated on two hypothetical examples for simple and complex aquifer geometries, measurement error conditions, and different HS solution parameter sets. Identified results indicated that the proposed simulation-optimization model is an effective way and may be used to solve the inverse pollution source identification problems.

  8. Numerical simulation of CO2 leakage from a geologic disposal reservoir including transitions from super- to sub-critical conditions, and boiling of liquid of CO2

    SciTech Connect

    Pruess, Karsten

    2003-03-31

    The critical point of CO{sub 2} is at temperature and pressure conditions of T{sub crit} = 31.04 C, P{sub crit} = 73.82 bar. At lower (subcritical) temperatures and/or pressures, CO{sub 2} can exist in two different phase states, a liquid and a gaseous state, as well as in two-phase mixtures of these states. Disposal of CO{sub 2} into brine formations would be made at supercritical pressures. However, CO{sub 2} escaping from the storage reservoir may migrate upwards towards regions with lower temperatures and pressures, where CO{sub 2} would be in subcritical conditions. An assessment of the fate of leaking CO{sub 2} requires a capability to model not only supercritical but also subcritical CO{sub 2}, as well as phase changes between liquid and gaseous CO{sub 2} in sub-critical conditions. We have developed a methodology for numerically simulating the behavior of water-CO{sub 2} mixtures in permeable media under conditions that may include liquid, gaseous, and supercritical CO{sub 2}. This has been applied to simulations of leakage from a deep storage reservoir in which a rising CO{sub 2} plume undergoes transitions from supercritical to subcritical conditions. We find strong cooling effects when liquid CO{sub 2} rises to elevations where it begins to boil and evolve a gaseous CO{sub 2} phase. A three-phase zone forms (aqueous - liquid - gas), which over time becomes several hundred meters thick as decreasing temperatures permit liquid CO{sub 2} to advance to shallower elevations. Fluid mobilities are reduced in the three-phase region from phase interference effects. This impedes CO{sub 2} upflow, causes the plume to spread out laterally, and gives rise to dispersed CO{sub 2} discharge at the land surface. Our simulation suggests that temperatures along a CO{sub 2} leakage path may decline to levels low enough so that solid water ice and CO{sub 2} hydrate phases may be formed.

  9. An Assessment of Some Design Constraints on Heat Production of a 3D Conceptual EGS Model Using an Open-Source Geothermal Reservoir Simulation Code

    SciTech Connect

    Yidong Xia; Mitch Plummer; Robert Podgorney; Ahmad Ghassemi

    2016-02-01

    Performance of heat production process over a 30-year period is assessed in a conceptual EGS model with a geothermal gradient of 65K per km depth in the reservoir. Water is circulated through a pair of parallel wells connected by a set of single large wing fractures. The results indicate that the desirable output electric power rate and lifespan could be obtained under suitable material properties and system parameters. A sensitivity analysis on some design constraints and operation parameters indicates that 1) the fracture horizontal spacing has profound effect on the long-term performance of heat production, 2) the downward deviation angle for the parallel doublet wells may help overcome the difficulty of vertical drilling to reach a favorable production temperature, and 3) the thermal energy production rate and lifespan has close dependence on water mass flow rate. The results also indicate that the heat production can be improved when the horizontal fracture spacing, well deviation angle, and production flow rate are under reasonable conditions. To conduct the reservoir modeling and simulations, an open-source, finite element based, fully implicit, fully coupled hydrothermal code, namely FALCON, has been developed and used in this work. Compared with most other existing codes that are either closed-source or commercially available in this area, this new open-source code has demonstrated a code development strategy that aims to provide an unparalleled easiness for user-customization and multi-physics coupling. Test results have shown that the FALCON code is able to complete the long-term tests efficiently and accurately, thanks to the state-of-the-art nonlinear and linear solver algorithms implemented in the code.

  10. Development and Application of a Computer Simulation Program to Enhance the Clinical Problem-Solving Skills of Students.

    ERIC Educational Resources Information Center

    Boh, Larry E.; And Others

    1987-01-01

    A project to (1) develop and apply a microcomputer simulation program to enhance clinical medication problem solving in preclerkship and clerkship students and (2) perform an initial formative evaluation of the simulation is described. A systematic instructional design approach was used in applying the simulation to the disease state of rheumatoid…

  11. Simulated effects of the 2003 permitted withdrawals and water-management alternatives on reservoir storage and firm yields of three surface-water supplies, Ipswich River Basin, Massachusetts

    USGS Publications Warehouse

    Zarriello, Phillip J.

    2004-01-01

    The Hydrologic Simulation ProgramFORTRAN (HSPF) model of the Ipswich River Basin previously developed by the U.S. Geological Survey was modified to evaluate the effects of the 2003 withdrawal permits and water-management alternatives on reservoir storage and yields of the Lynn, Peabody, and SalemBeverly water-supply systems. These systems obtain all or part of their water from the Ipswich River Basin. The HSPF model simulated the complex water budgets to the three supply systems, including effects of regulations that restrict withdrawals by the time of year, minimum streamflow thresholds, and the capacity of each system to pump water from the river. The 2003 permits restrict withdrawals from the Ipswich River between November 1 and May 31 to streamflows above a 1.0 cubic foot per second per square mile (ft3/s/mi2) threshold, to high flows between June 1 and October 31, and to a maximum annual volume. Yields and changes in reservoir storage over the 35-year simulation period (196195) were also evaluated for each system with a hypothetical low-capacity pump, alternative seasonal streamflow thresholds, and withdrawals that result in successive failures (depleted storage). The firm yields, the maximum yields that can be met during a severe drought, calculated for each water-supply system, under the 2003 permitted withdrawals, were 7.31 million gallons per day (Mgal/d) for the Lynn, 3.01 Mgal/d for the Peabody, and 7.98 Mgal/d for the SalemBeverly systems; these yields are 31, 49, and 21 percent less than their average 19982000 demands, respectively. The simulations with the same permit restrictions and a hypothetical low-capacity pump for each system resulted in slightly increased yields for the Lynn and SalemBeverly systems, but a slightly decreased yield for the Peabody system. Simulations to evaluate the effects of alternative streamflow thresholds on water supply indicated that firm yields were generally about twice as sensitive to decreases in the November

  12. Simulation research on improved regularized solution of the inverse problem in spectral extinction measurements.

    PubMed

    Mroczka, Janusz; Szczuczyński, Damian

    2012-04-10

    We present further results of the simulation research on the constrained regularized least squares (CRLS) solution of the ill-conditioned inverse problem in spectral extinction (turbidimetric) measurements, which we originally presented in this journal [Appl. Opt. 49, 4591 (2010)]. The inverse problem consists of determining the particle size distribution (PSD) function of a particulate system on the basis of a measured extinction coefficient as a function of wavelength. In our previous paper, it was shown that under assumed conditions the problem can be formulated in terms of the discretized Fredholm integral equation of the first kind. The CRLS method incorporates two constraints, which the PSD sought will satisfy: nonnegativity of the PSD values and normalization of the PSD to unity when integrated over the whole range of particle size, into the regularized least squares (RLS) method. This leads to the quadratic programming problem, which is solved by means of the active set algorithm within the research. The simulation research that is the subject of the present paper is a continuation and extension of the research described in our previous paper. In the present research, the performance of the CRLS method variants is compared not only to the corresponding RLS method variants but also to other regularization techniques: the truncated generalized singular value decomposition and the filtered generalized singular value decomposition, as well as nonlinear iterative algorithms: The Twomey algorithm and the Twomey-Markowski algorithm. Moreover, two methods of selecting the optimum value of the regularization parameter are considered: The L-curve method and the generalized cross validation method. The results of our simulation research provide even stronger proof that the CRLS method performs considerably better with reconstruction of PSD than other inversing methods, in terms of better fidelity and smaller uncertainty.

  13. Simulation of product distribution at PT Anugrah Citra Boga by using capacitated vehicle routing problem method

    NASA Astrophysics Data System (ADS)

    Lamdjaya, T.; Jobiliong, E.

    2017-01-01

    PT Anugrah Citra Boga is a food processing industry that produces meatballs as their main product. The distribution system of the products must be considered, because it needs to be more efficient in order to reduce the shipment cost. The purpose of this research is to optimize the distribution time by simulating the distribution channels with capacitated vehicle routing problem method. Firstly, the distribution route is observed in order to calculate the average speed, time capacity and shipping costs. Then build the model using AIMMS software. A few things that are required to simulate the model are customer locations, distances, and the process time. Finally, compare the total distribution cost obtained by the simulation and the historical data. It concludes that the company can reduce the shipping cost around 4.1% or Rp 529,800 per month. By using this model, the utilization rate can be more optimal. The current value for the first vehicle is 104.6% and after the simulation it becomes 88.6%. Meanwhile, the utilization rate of the second vehicle is increase from 59.8% to 74.1%. The simulation model is able to produce the optimal shipping route with time restriction, vehicle capacity, and amount of vehicle.

  14. Application of advanced reservoir characterization, simulation, and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, west Texas (Delaware Basin). Annual progress report, March 31, 1995--March 31, 1996

    SciTech Connect

    Dutton, S.P.; Hovorka, S.D.; Cole, A.G.

    1996-08-01

    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 field development. Reservoirs in the Delaware Mountain Group 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. Detailed correlations of the Ramsey sandstone reservoirs in Geraldine Ford field suggest that lateral sandstone continuity is less than interpreted by previous studies. The degree of lateral heterogeneity in the reservoir sandstones suggests that they were deposited by eolian-derived turbidites. According to the eolian-derived turbidite model, sand dunes migrated across the exposed shelf to the shelf break during sea-level lowstands and provided well sorted sand for turbidity currents or grain flows into the deep basin.

  15. Analysis of real-time reservoir monitoring : reservoirs, strategies, & modeling.

    SciTech Connect

    Mani, Seethambal S.; van Bloemen Waanders, Bart Gustaaf; Cooper, Scott Patrick; Jakaboski, Blake Elaine; Normann, Randy Allen; Jennings, Jim; Gilbert, Bob; Lake, Larry W.; Weiss, Chester Joseph; Lorenz, John Clay; Elbring, Gregory Jay; Wheeler, Mary Fanett; Thomas, Sunil G.; Rightley, Michael J.; Rodriguez, Adolfo; Klie, Hector; Banchs, Rafael; Nunez, Emilio J.; Jablonowski, Chris

    2006-11-01

    The project objective was to detail better ways to assess and exploit intelligent oil and gas field information through improved modeling, sensor technology, and process control to increase ultimate recovery of domestic hydrocarbons. To meet this objective we investigated the use of permanent downhole sensors systems (Smart Wells) whose data is fed real-time into computational reservoir models that are integrated with optimized production control systems. The project utilized a three-pronged approach (1) a value of information analysis to address the economic advantages, (2) reservoir simulation modeling and control optimization to prove the capability, and (3) evaluation of new generation sensor packaging to survive the borehole environment for long periods of time. The Value of Information (VOI) decision tree method was developed and used to assess the economic advantage of using the proposed technology; the VOI demonstrated the increased subsurface resolution through additional sensor data. Our findings show that the VOI studies are a practical means of ascertaining the value associated with a technology, in this case application of sensors to production. The procedure acknowledges the uncertainty in predictions but nevertheless assigns monetary value to the predictions. The best aspect of the procedure is that it builds consensus within interdisciplinary teams The reservoir simulation and modeling aspect of the project was developed to show the capability of exploiting sensor information both for reservoir characterization and to optimize control of the production system. Our findings indicate history matching is improved as more information is added to the objective function, clearly indicating that sensor information can help in reducing the uncertainty associated with reservoir characterization. Additional findings and approaches used are described in detail within the report. The next generation sensors aspect of the project evaluated sensors and packaging

  16. Volume 4: Characterization of representative reservoirs -- Gulf of Mexico field, U-8 reservoir

    SciTech Connect

    Koperna, G.J. Jr.; Johnson, H.R.; Salamy, S.P.; Reeves, T.K.; Sawyer, W.K.; Kimbrell, W.C.; Schenewerk, P.A.

    1998-07-01

    A reservoir study was performed using a publicly available black oil simulator to history match and predict the performance of a Gulf of Mexico reservoir. The first objective of this simulation study was to validate the Black Oil Applied Simulation Tool version three for personal computers (BOAST3-PC) model to ensure the integrity of the simulation runs. Once validation was completed, a field history match for the Gulf of Mexico U-8 oil reservoir was attempted. A verbal agreement was reached with the operator of this reservoir to blindcode the name and location of the reservoir. In return, the operator supplied data and assistance in regards to the technical aspects of the research. On the basis of the best history match, different secondary recovery techniques were simulated as a predictive study for enhancing the reservoir productivity.

  17. Parallel Simulation of Three-Dimensional Free-Surface Fluid Flow Problems

    SciTech Connect

    BAER,THOMAS A.; SUBIA,SAMUEL R.; SACKINGER,PHILIP A.

    2000-01-18

    We describe parallel simulations of viscous, incompressible, free surface, Newtonian fluid flow problems that include dynamic contact lines. The Galerlin finite element method was used to discretize the fully-coupled governing conservation equations and a ''pseudo-solid'' mesh mapping approach was used to determine the shape of the free surface. In this approach, the finite element mesh is allowed to deform to satisfy quasi-static solid mechanics equations subject to geometric or kinematic constraints on the boundaries. As a result, nodal displacements must be included in the set of problem unknowns. Issues concerning the proper constraints along the solid-fluid dynamic contact line in three dimensions are discussed. Parallel computations are carried out for an example taken from the coating flow industry, flow in the vicinity of a slot coater edge. This is a three-dimensional free-surface problem possessing a contact line that advances at the web speed in one region but transitions to static behavior in another part of the flow domain. Discussion focuses on parallel speedups for fixed problem size, a class of problems of immediate practical importance.

  18. Simulation of Fort Peck Lake Temperature Releases and Downstream Missouri River Temperatures

    DTIC Science & Technology

    2007-12-09

    18 Table 5. Fort Peck Reservoir simulation variations... Reservoir simulation variations and data years used in the reservoir temperature analysis. Analysis Parameter Variation HydrodynamicYear Meteorological

  19. Multiphase Simulated Annealing Based on Boltzmann and Bose-Einstein Distribution Applied to Protein Folding Problem

    PubMed Central

    Liñán-García, Ernesto; Sánchez-Hernández, Juan Paulo; González-Barbosa, J. Javier; González-Flores, Carlos

    2016-01-01

    A new hybrid Multiphase Simulated Annealing Algorithm using Boltzmann and Bose-Einstein distributions (MPSABBE) is proposed. MPSABBE was designed for solving the Protein Folding Problem (PFP) instances. This new approach has four phases: (i) Multiquenching Phase (MQP), (ii) Boltzmann Annealing Phase (BAP), (iii) Bose-Einstein Annealing Phase (BEAP), and (iv) Dynamical Equilibrium Phase (DEP). BAP and BEAP are simulated annealing searching procedures based on Boltzmann and Bose-Einstein distributions, respectively. DEP is also a simulated annealing search procedure, which is applied at the final temperature of the fourth phase, which can be seen as a second Bose-Einstein phase. MQP is a search process that ranges from extremely high to high temperatures, applying a very fast cooling process, and is not very restrictive to accept new solutions. However, BAP and BEAP range from high to low and from low to very low temperatures, respectively. They are more restrictive for accepting new solutions. DEP uses a particular heuristic to detect the stochastic equilibrium by applying a least squares method during its execution. MPSABBE parameters are tuned with an analytical method, which considers the maximal and minimal deterioration of problem instances. MPSABBE was tested with several instances of PFP, showing that the use of both distributions is better than using only the Boltzmann distribution on the classical SA. PMID:27413369

  20. Multiphase Simulated Annealing Based on Boltzmann and Bose-Einstein Distribution Applied to Protein Folding Problem.

    PubMed

    Frausto-Solis, Juan; Liñán-García, Ernesto; Sánchez-Hernández, Juan Paulo; González-Barbosa, J Javier; González-Flores, Carlos; Castilla-Valdez, Guadalupe

    2016-01-01

    A new hybrid Multiphase Simulated Annealing Algorithm using Boltzmann and Bose-Einstein distributions (MPSABBE) is proposed. MPSABBE was designed for solving the Protein Folding Problem (PFP) instances. This new approach has four phases: (i) Multiquenching Phase (MQP), (ii) Boltzmann Annealing Phase (BAP), (iii) Bose-Einstein Annealing Phase (BEAP), and (iv) Dynamical Equilibrium Phase (DEP). BAP and BEAP are simulated annealing searching procedures based on Boltzmann and Bose-Einstein distributions, respectively. DEP is also a simulated annealing search procedure, which is applied at the final temperature of the fourth phase, which can be seen as a second Bose-Einstein phase. MQP is a search process that ranges from extremely high to high temperatures, applying a very fast cooling process, and is not very restrictive to accept new solutions. However, BAP and BEAP range from high to low and from low to very low temperatures, respectively. They are more restrictive for accepting new solutions. DEP uses a particular heuristic to detect the stochastic equilibrium by applying a least squares method during its execution. MPSABBE parameters are tuned with an analytical method, which considers the maximal and minimal deterioration of problem instances. MPSABBE was tested with several instances of PFP, showing that the use of both distributions is better than using only the Boltzmann distribution on the classical SA.

  1. Simulation of Sub-Drains Performance Using Visual MODFLOW for Slope Water Seepage Problem

    NASA Astrophysics Data System (ADS)

    Baharuddin, M. F. T.; Tajudin, S. A. A.; Abidin, M. H. Z.; Yusoff, N. A.

    2016-07-01

    Numerical simulation technique was used for investigating water seepage problem at the Botanic Park Kuala Lumpur. A proposed sub-drains installation in problematic site location was simulated using Modular Three-Dimensional Finite Difference Groundwater Flow (MODFLOW) software. The results of simulation heads during transient condition showed that heads in between 43 m (water seepage occurred at level 2) until 45 m (water seepage occurred at level 4) which heads measurement are referred to mean sea level. However, elevations measurements for level 2 showed the values between 41 to 42 m from mean sea level and elevations for level 4 between 42 to 45 m from mean sea level. These results indicated an increase in heads for level 2 and level 4 between 1 to 2 m when compared to elevations slope at the level 2 and level 4. The head increases surpass the elevation level of the slope area that causing water seepage at level 2 and level 4. In order to overcome this problems, the heads level need to be decrease to 1 until 2 m by using two options of sub-drain dimension size. Sub-drain with the dimension of 0.0750 m (diameter), 0.10 m (length) and using 4.90 m spacing was the best method to use as it was able to decrease the heads to the required levels of 1 to 2 m.

  2. Using Elearning techniques to support problem based learning within a clinical simulation laboratory.

    PubMed

    Docherty, Charles; Hoy, Derek; Topp, Helena; Trinder, Kathryn

    2004-01-01

    This paper details the results of the first phase of a project that used eLearning to support students' learning within a simulated environment. The locus was a purpose built Clinical Simulation Laboratory (CSL) where the School's newly adopted philosophy of Problem Based Learning (PBL) was challenged through lecturers reverting to traditional teaching methods. The solution, a student-centred, problem-based approach to the acquisition of clinical skills was developed using learning objects embedded within web pages that substituted for lecturers providing instruction and demonstration. This allowed lecturers to retain their facilitator role, and encouraged students to explore, analyse and make decisions within the safety of a clinical simulation. Learning was enhanced through network communications and reflection on video performances of self and others. Evaluations were positive, students demonstrating increased satisfaction with PBL, improved performance in exams, and increased self-efficacy in the performance of nursing activities. These results indicate that an elearning approach can support PBL in delivering a student centred learning experience.

  3. A Volume-of-Fluid based simulation method for wave impact problems

    NASA Astrophysics Data System (ADS)

    Kleefsman, K. M. T.; Fekken, G.; Veldman, A. E. P.; Iwanowski, B.; Buchner, B.

    2005-06-01

    In this paper, some aspects of water impact and green water loading are considered by numerically investigating a dambreak problem and water entry problems. The numerical method is based on the Navier-Stokes equations that describe the flow of an incompressible viscous fluid. The equations are discretised on a fixed Cartesian grid using the finite volume method. Even though very small cut cells can appear when moving an object through the fixed grid, the method is stable. The free surface is displaced using the Volume-of-Fluid method together with a local height function, resulting in a strictly mass conserving method. The choice of boundary conditions at the free surface appears to be crucial for the accuracy and robustness of the method. For validation, results of a dambreak simulation are shown that can be compared with measurements. A box has been placed in the flow, as a model for a container on the deck of an offshore floater on which forces are calculated. The water entry problem has been investigated by dropping wedges with different dead-rise angles, a cylinder and a cone into calm water with a prescribed velocity. The resulting free surface dynamics, with the sideways jets, has been compared with photographs of experiments. Also a comparison of slamming coefficients with theory and experimental results has been made. Finally, a drop test with a free falling wedge has been simulated.

  4. Solving the problem of negative populations in approximate accelerated stochastic simulations using the representative reaction approach.

    PubMed

    Kadam, Shantanu; Vanka, Kumar

    2013-02-15

    Methods based on the stochastic formulation of chemical kinetics have the potential to accurately reproduce the dynamical behavior of various biochemical systems of interest. However, the computational expense makes them impractical for the study of real systems. Attempts to render these methods practical have led to the development of accelerated methods, where the reaction numbers are modeled by Poisson random numbers. However, for certain systems, such methods give rise to physically unrealistic negative numbers for species populations. The methods which make use of binomial variables, in place of Poisson random numbers, have since become popular, and have been partially successful in addressing this problem. In this manuscript, the development of two new computational methods, based on the representative reaction approach (RRA), has been discussed. The new methods endeavor to solve the problem of negative numbers, by making use of tools like the stochastic simulation algorithm and the binomial method, in conjunction with the RRA. It is found that these newly developed methods perform better than other binomial methods used for stochastic simulations, in resolving the problem of negative populations.

  5. 3D inversion of time-lapse CSEM data for reservoir monitoring

    NASA Astrophysics Data System (ADS)

    Black, N.; Wilson, G. A.; Zhdanov, M. S.

    2010-12-01

    Effective reservoir monitoring requires time-lapse reservoir information throughout the interwell volume. The ability to understand and control reservoir behavior over the course of production allows for optimization of reservoir performance and production strategies. Good monitoring information makes it possible to improve the timing and location of new drilling (for both production and injection wells), to recognize flow paths, and to map oil that has been bypassed. Recent studies have inferred the feasibility of time-lapse marine controlled-source electromagnetic (CSEM) methods for the monitoring of offshore oil and gas fields. However, quantitative interpretations to ascertain what reservoir information may be recovered have not been performed. The time-lapse CSEM inverse problem can be highly constrained since the geometry of the reservoir is established prior from high resolution seismic surveys, rock and fluid properties are measured from well logs, and multiple history matched production scenarios are contained in dynamic reservoir models. We present a 3D inversion study of synthetic time-lapse CSEM data modeled from dynamic reservoir simulations. We demonstrate that even with few constraints on the model, the hydrocarbon-water front can be recovered from 3D inversion.

  6. Increasing Heavy Oil Reserves in the Wilmington Oil Field Through Advanced Reservoir Characterization and Thermal Production Technologies

    SciTech Connect

    Scott Hara

    1997-08-08

    The project involves improving thermal recovery techniques in a slope and basin clastic (SBC) reservoir in the Wilmington field, Los Angeles Co., Calif. using advanced reservoir characterization and thermal production technologies. The existing steamflood in the Tar zone of Fault Block (FB) II-A has been relatively inefficient because of several producibility problems which are common in SBC reservoirs. Inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil, and nonuniform distribution of remaining oil have all contributed to poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated formation sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. The advanced technologies to be applied include: (1) Develop three-dimensional (3-D) deterministic and stochastic geologic models. (2) Develop 3-D deterministic and stochastic thermal reservoir simulation models to aid in reservoir management and subsequent development work. (3) Develop computerized 3-D visualizations of the geologic and reservoir simulation models to aid in analysis. (4) Perform detailed study on the geochemical interactions between the steam and the formation rock and fluids. (5) Pilot steam injection and production via four new horizontal wells (2 producers and 2 injectors). (6) Hot water alternating steam (WAS) drive pilot in the existing steam drive area to improve thermal efficiency. (7) Installing a 2100 foot insulated, subsurface harbor channel crossing to supply steam to an island location. (8) Test a novel alkaline steam completion technique to control well sanding problems and fluid entry profiles. (9) Advanced reservoir management through computer-aided access to production and

  7. Increasing Heavy Oil Reserves in the Wilmington Oil Field Through Advanced Reservoir Characterization and Thermal Production Technologies

    SciTech Connect

    Scott Hara

    1998-03-03

    The project involves improving thermal recovery techniques in a slope and basin clastic (SBC) reservoir in the Wilmington field, Los Angeles Co., Calif. using advanced reservoir characterization and thermal production technologies. The existing steamflood in the Tar zone of Fault Block (FB) II-A has been relatively inefficient because of several producibility problems which are common in SBC reservoirs. Inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil, and nonuniform distribution of remaining oil have all contributed to poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated formation sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. The advanced technologies to be applied include: (1) Develop three-dimensional (3-D) deterministic and stochastic geologic models. (2) Develop 3-D deterministic and stochastic thermal reservoir simulation models to aid in reservoir management and subsequent development work. (3) Develop computerized 3-D visualizations of the geologic and reservoir simulation models to aid in analysis. (4) Perform detailed study on the geochemical interactions between the steam and the formation rock and fluids. (5) Pilot steam injection and production via four new horizontal wells (2 producers and 2 injectors). (6) Hot water alternating steam (WAS) drive pilot in the existing steam drive area to improve thermal efficiency. (7) Installing a 2100 foot insulated, subsurface harbor channel crossing to supply steam to an island location. (8) Test a novel alkaline steam completion technique to control well sanding problems and fluid entry profiles. (9) Advanced reservoir management through computer-aided access to production and

  8. Simulation Software

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Various NASA Small Business Innovation Research grants from Marshall Space Flight Center, Langley Research Center and Ames Research Center were used to develop the 'kernel' of COMCO's modeling and simulation software, the PHLEX finite element code. NASA needed it to model designs of flight vehicles; one of many customized commercial applications is UNISIM, a PHLEX-based code for analyzing underground flows in oil reservoirs for Texaco, Inc. COMCO's products simulate a computational mechanics problem, estimate the solution's error and produce the optimal hp-adapted mesh for the accuracy the user chooses. The system is also used as a research or training tool in universities and in mechanical design in industrial corporations.

  9. Improving Gas Storage Development Planning Through Simulation-Optimization

    SciTech Connect

    Johnson, V.M.; Ammer, J.; Trick, M.D.

    2000-07-25

    This is the first of two papers describing the application of simulator-optimization methods to a natural gas storage field development planning problem. The results presented here illustrate the large gains in cost-effectiveness that can be made by employing the reservoir simulator as the foundation for a wide-ranging search for solutions to management problems. The current paper illustrates the application of these techniques given a deterministic view of the reservoir. A companion paper will illustrate adaptations needed to accommodate uncertainties regarding reservoir properties.

  10. Considering social and environmental concerns as reservoir operating objectives

    NASA Astrophysics Data System (ADS)

    Tilmant, A.; Georis, B.; Doulliez, P.

    2003-04-01

    Sustainability principles are now widely recognized as key criteria for water resource development schemes, such as hydroelectric and multipurpose reservoirs. Development decisions no longer rely solely on economic grounds, but also consider environmental and social concerns through the so-called environmental and social impact assessments. The objective of this paper is to show that environmental and social concerns can also be addressed in the management (operation) of existing or projected reservoir schemes. By either adequately exploiting the results of environmental and social impact assessments, or by carrying out survey of water users, experts and managers, efficient (Pareto optimal) reservoir operating rules can be derived using flexible mathematical programming techniques. By reformulating the problem as a multistage flexible constraint satisfaction problem, incommensurable and subjective operating objectives can contribute, along with classical economic objectives, to the determination of optimal release decisions. Employed in a simulation mode, the results can be used to assess the long-term impacts of various operating rules on the social well-being of affected populations as well as on the integrity of the environment. The methodology is illustrated with a reservoir reallocation problem in Chile.

  11. Modifying Reservoir Operations to Improve Capabilities for Meeting Water Supply Needs During Drought

    DTIC Science & Technology

    1990-12-01

    economic analyses are also performed either with or using output from reservoir simulation models; are particularly pertinent to studies of operational...ways using a reservoir simulation model. For example, for a given demand level or targeted diversion amount, the actual diversion and diversion...reallocation and other modifications in operation of existing reservoirs. Traditional yield analysis involves using a reservoir simulation model

  12. Optimization of Multiple-Purpose Reservoir Systems Operations: A Review of Modeling and Analysis Approaches

    DTIC Science & Technology

    1991-01-01

    interactive menu-driven microcomputer single- reservoir simulation model (Ford 1990). RESQ performs the same basic computations as HEC-3 but is limited...capability of routing conservative constituents through a single reservoir . Simulation Models Which Use Network Flow Programming Algorithms The reservoir...Raphson convergence technique, into a Hydrologic Engineering Center reservoir simulation model to develop a method for determining the economically optimum

  13. Molecular simulation of protein-surface interactions: Benefits, problems, solutions, and future directions (Review)

    PubMed Central

    Latour, Robert A.

    2009-01-01

    While the importance of protein adsorption to materials surfaces is widely recognized, little is understood at this time regarding how to design surfaces to control protein adsorption behavior. All-atom empirical force field molecular simulation methods have enormous potential to address this problem by providing an approach to directly investigate the adsorption behavior of peptides and proteins at the atomic level. As with any type of technology, however, these methods must be appropriately developed and applied if they are to provide realistic and useful results. Three issues that are particularly important for the accurate simulation of protein adsorption behavior are the selection of a valid force field to represent the atomic-level interactions involved, the accurate representation of solvation effects, and system sampling. In this article, each of these areas is addressed and future directions for continued development are presented. PMID:19809597

  14. Fluid pressure responses for a Devil's Slide-like system: problem formulation and simulation

    USGS Publications Warehouse

    Thomas, Matthew A.; Loague, Keith; Voss, Clifford I.

    2015-01-01

    This study employs a hydrogeologic simulation approach to investigate subsurface fluid pressures for a landslide-prone section of the central California, USA, coast known as Devil's Slide. Understanding the relative changes in subsurface fluid pressures is important for systems, such as Devil's Slide, where slope creep can be interrupted by episodic slip events. Surface mapping, exploratory core, tunnel excavation records, and dip meter data were leveraged to conceptualize the parameter space for three-dimensional (3D) Devil's Slide-like simulations. Field observations (i.e. seepage meter, water retention, and infiltration experiments; well records; and piezometric data) and groundwater flow simulation (i.e. one-dimensional vertical, transient, and variably saturated) were used to design the boundary conditions for 3D Devil's Slide-like problems. Twenty-four simulations of steady-state saturated subsurface flow were conducted in a concept-development mode. Recharge, heterogeneity, and anisotropy are shown to increase fluid pressures for failure-prone locations by up to 18.1, 4.5, and 1.8% respectively. Previous estimates of slope stability, driven by simple water balances, are significantly improved upon with the fluid pressures reported here. The results, for a Devil's Slide-like system, provide a foundation for future investigations

  15. Simulations for Complex Fluid Flow Problems from Berkeley Lab's Center for Computational Sciences and Engineering (CCSE)

    DOE Data Explorer

    The Center for Computational Sciences and Engineering (CCSE) develops and applies advanced computational methodologies to solve large-scale scientific and engineering problems arising in the Department of Energy (DOE) mission areas involving energy, environmental, and industrial technology. The primary focus is in the application of structured-grid finite difference methods on adaptive grid hierarchies for compressible, incompressible, and low Mach number flows. The diverse range of scientific applications that drive the research typically involve a large range of spatial and temporal scales (e.g. turbulent reacting flows) and require the use of extremely large computing hardware, such as the 153,000-core computer, Hopper, at NERSC. The CCSE approach to these problems centers on the development and application of advanced algorithms that exploit known separations in scale; for many of the application areas this results in algorithms are several orders of magnitude more efficient than traditional simulation approaches.

  16. Movement simulation of the variable masses in the Gylden-Meshcherskii problem

    SciTech Connect

    Starinova, Olga L.; Salmin, Vadim V.

    2014-12-10

    The Gylden-Meshcherskii problem is used for various cases of dynamics of two points of the variable mass. For example, it describes of double star evolution due to mass loss at the photon expense and the corpuscular activity. Except, it is mathematical model for the movement of spacecraft with propulsion system. In the present work the mass variation laws, allowing a stationary form of the movement differential equations are considered. Movement simulation for all cases was conducted. The relative movement trajectories was constructed as for known Eddington-Jeans laws and for other mass variation laws.

  17. Neighbourhood generation mechanism applied in simulated annealing to job shop scheduling problems

    NASA Astrophysics Data System (ADS)

    Cruz-Chávez, Marco Antonio

    2015-11-01

    This paper presents a neighbourhood generation mechanism for the job shop scheduling problems (JSSPs). In order to obtain a feasible neighbour with the generation mechanism, it is only necessary to generate a permutation of an adjacent pair of operations in a scheduling of the JSSP. If there is no slack time between the adjacent pair of operations that is permuted, then it is proven, through theory and experimentation, that the new neighbour (schedule) generated is feasible. It is demonstrated that the neighbourhood generation mechanism is very efficient and effective in a simulated annealing.

  18. Innovative techniques for the description of reservoir heterogeneity using tracers. Final report, October 1992--December 1993

    SciTech Connect

    Pope, G.A.; Sepehrnoori, K.; Delshad, M.; Ferreira, L.; Gupta, A.; Maroongroge, V.

    1994-11-01

    This is the final report of a three year research project on the use of tracers for reservoir characterization. The objective of this research was to develop advanced, innovative techniques for the description of reservoir characteristics using both single-well backflow and interwell tracer tests. (1) The authors implemented and validated tracer modeling features in a compositional simulator (UTCOMP). (2) They developed and applied a new single well tracer test for estimating reservoir heterogeneity. (3) They developed and applied a new single well tracer test for estimating reservoir wettability in-situ. (4) They developed a new, simple and efficient method to analyze two well tracer tests based upon type curve matching and illustrated its use with actual field tracer data. (5) They developed a new method for deriving an integrated reservoir description based upon combinatorial optimization schemes. (6) They developed a new, interwell tracer test for reservoir heterogeneity called vertical tracer profiling (VTP) and demonstrated its advantages over conventional interwell tracer testing. (7) They developed a simple and easy analytical method to estimate swept pore volume from interwell tracer data and showed both the theoretical basis for this method and its practical utility. (8) They made numerous enhancements to our compositional reservoir simulator such as including the full permeability tensor, adding faster solvers, improving its speed and robustness and making it easier to use (better I/0) for tracer simulation problems. (9) They applied the enhanced version of UTCOMP to the analysis of interwell tracer data using perfluorocarbons at Elks Hill Naval Petroleum Reserve. All of these accomplishments taken together have significantly improved the state of reservoir tracer technology and have demonstrated that it is a far more powerful and useful tool for quantitative reservoir characterization than previously realized or practiced by the industry.

  19. Naturally fractured reservoirs: Optimized E and P strategies using a reaction-transport-mechanical simulator in an integrated approach. Summary of project accomplishments; Final report, September 30, 1998

    SciTech Connect

    Ortoleva, P.J.; Sundberg, K.R.; Hoak, T.E.

    1998-12-01

    Major accomplishments of this project occurred in three primary categories: (1) fractured reservoir location and characteristics prediction for exploration and production planning; (2) implications of geologic data analysis and synthesis for exploration and development programs; and (3) fractured reservoir production modeling. The results in each category will be discussed in turn. Seven detailed reports have been processed separately.

  20. Evaluation of Equations of State and Mixing Models for Simulating the Brine-CO2 System with a Lattice Boltzmann Model Under Reservoir Conditions

    NASA Astrophysics Data System (ADS)

    Schaap, M. G.

    2013-12-01

    This DOE-funded study is a collaboration between Oregon State University (led by Dr. Dorthe Wildenschild) and the University of Arizona to investigate pore-scale aspects of capillary trapping to enhance the efficiency of geological CO2 sequestration in deep saline aquifers where super-critical conditions prevail. Compared to most current reservoir-scale studies, our research takes several steps back in scale to observe and model trapping at the pore-scale using a combination of computed micro-tomography imaging (performed by OSU) and multi-phase/multi-component lattice Boltzmann (LB) simulations (carried out by UA). The main objective is to quantify how pore-scale mechanisms translate into continuum scale properties that can subsequently support improved modelling of sequestration at large spatio-temporal scales. For the purposes of this project it is important to correctly simulate the physical conditions under which super-critical CO2 will be present after injection into the host rock. In practice this means that the LB model should be able to handle the pressures (P), densities (ρ), temperatures (T) that prevail in deep geological media. A logical way of dealing with is is to combine a single-component LB model with and Equation of State (EOS) that describes the physical interrelations among P, ρ and T (Yuan and Scheafer, 2006). Previously, we showed that the Peng-Robinson (PR) EOS provides an excellent fit to super-critical conditions for the pure CO2 system. However, simulating pure-CO2 systems is not sufficient as the super-critical CO2 will co-exist (and interact) with brine present in the saline aquifers. In effect this means that we need to simulate multi-component systems: one phase being the super-critical CO2, the other phase being a brine of varying salinity. Previously, we have used used a Shan-Chen-type model (Shan Chen, 1993, 1994) as modified by Martys and Chen (1996) for simplified capillari pressure dominated air-water systems in porous media

  1. A simulation study of inorganic sulfur cycling in the water level fluctuation zone of the Three Gorges Reservoir, China and the implications for mercury methylation.

    PubMed

    Liu, Jiang; Jiang, Tao; Huang, Rong; Wang, Dingyong; Zhang, Jinzhong; Qian, Sheng; Yin, Deliang; Chen, Hong

    2017-01-01

    The water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) in China experiences a drying and wetting rotation every year, and the water level induced redox variation may influence inorganic sulfur speciation and mercury methylation. In this work, a simulative flooding and drying experiment and a sulfate added flooding experiment were conducted to study this topic. The results showed that sulfate was reduced from the 10th d during the flooding period based on the detected sulfide in water and the increased elemental sulfur (S(0)) in sediment. Sulfate reduction and sulfide re-oxidation led to the increase of S(0) contents with the maximal values of 1.86 and 0.46 mg kg(-1) during the flooding and drying period, respectively. Methylmercury (MeHg) content in sediment displayed a rising trend (0.16-0.28 μg kg(-1)) in the first 40 d during the flooding period, and then declined from 0.28 to 0.15 μg kg(-1). A positive correlation between MeHg content and S(0) content in soil (r = 0.53, p < 0.05) was found during the flooding period, and a positive but not significant correlation between the percent of MeHg in THg (%MeHg) and S(0) content (r = 0.85, p = 0.08). In sulfate added flooding simulation, MeHg content in sediment did not increase with the sulfate concentration increasing. The increased pyrite in high-sulfate treatment may fix mercury through adsorption process. This study demonstrated that inorganic sulfur species especially S(0) and chromium reducible sulfur (CRS) play an important role on mercury methylation in the WLFZ of the TGR.

  2. Acoustic velocity log numerical simulation and saturation estimation of gas hydrate reservoir in Shenhu area, South China Sea.

    PubMed

    Xiao, Kun; Zou, Changchun; Xiang, Biao; Liu, Jieqiong

    2013-01-01

    Gas hydrate model and free gas model are established, and two-phase theory (TPT) for numerical simulation of elastic wave velocity is adopted to investigate the unconsolidated deep-water sedimentary strata in Shenhu area, South China Sea. The relationships between compression wave (P wave) velocity and gas hydrate saturation, free gas saturation, and sediment porosity at site SH2 are studied, respectively, and gas hydrate saturation of research area is estimated by gas hydrate model. In depth of 50 to 245 m below seafloor (mbsf), as sediment porosity decreases, P wave velocity increases gradually; as gas hydrate saturation increases, P wave velocity increases gradually; as free gas saturation increases, P wave velocity decreases. This rule is almost consistent with the previous research result. In depth of 195 to 220 mbsf, the actual measurement of P wave velocity increases significantly relative to the P wave velocity of saturated water modeling, and this layer is determined to be rich in gas hydrate. The average value of gas hydrate saturation estimated from the TPT model is 23.2%, and the maximum saturation is 31.5%, which is basically in accordance with simplified three-phase equation (STPE), effective medium theory (EMT), resistivity log (Rt), and chloride anomaly method.

  3. Acoustic Velocity Log Numerical Simulation and Saturation Estimation of Gas Hydrate Reservoir in Shenhu Area, South China Sea

    PubMed Central

    Xiao, Kun; Zou, Changchun; Xiang, Biao; Liu, Jieqiong

    2013-01-01

    Gas hydrate model and free gas model are established, and two-phase theory (TPT) for numerical simulation of elastic wave velocity is adopted to investigate the unconsolidated deep-water sedimentary strata in Shenhu area, South China Sea. The relationships between compression wave (P wave) velocity and gas hydrate saturation, free gas saturation, and sediment porosity at site SH2 are studied, respectively, and gas hydrate saturation of research area is estimated by gas hydrate model. In depth of 50 to 245 m below seafloor (mbsf), as sediment porosity decreases, P wave velocity increases gradually; as gas hydrate saturation increases, P wave velocity increases gradually; as free gas saturation increases, P wave velocity decreases. This rule is almost consistent with the previous research result. In depth of 195 to 220 mbsf, the actual measurement of P wave velocity increases significantly relative to the P wave velocity of saturated water modeling, and this layer is determined to be rich in gas hydrate. The average value of gas hydrate saturation estimated from the TPT model is 23.2%, and the maximum saturation is 31.5%, which is basically in accordance with simplified three-phase equation (STPE), effective medium theory (EMT), resistivity log (Rt), and chloride anomaly method. PMID:23935407

  4. Fully analogue photonic reservoir computer.

    PubMed

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-03-03

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers.

  5. Fully analogue photonic reservoir computer

    PubMed Central

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-01-01

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers. PMID:26935166

  6. Reservoir characterization of Pennsylvanian Sandstone Reservoirs. Annual report

    SciTech Connect

    Kelkar, M.

    1992-09-01

    This annual report describes the progress during the second year of a project on Reservoir Characterization of Pennsylvanian Sandstone Reservoirs. The report is divided into three sections: (i) reservoir description and scale-up procedures; (ii) outcrop investigation; (iii) in-fill drilling potential. The first section describes the methods by which a reservoir can be characterized, can be described in three dimensions, and can be scaled up with respect to its properties, appropriate for simulation purposes. The second section describes the progress on investigation of an outcrop. The outcrop is an analog of Bartlesville Sandstone. We have drilled ten wells behind the outcrop and collected extensive log and core data. The cores have been slabbed, photographed and the several plugs have been taken. In addition, minipermeameter is used to measure permeabilities on the core surface at six inch intervals. The plugs have been analyzed for the permeability and porosity values. The variations in property values will be tied to the geological descriptions as well as the subsurface data collected from the Glen Pool field. The third section discusses the application of geostatistical techniques to infer in-fill well locations. The geostatistical technique used is the simulated annealing technique because of its flexibility. One of the important reservoir data is the production data. Use of production data will allow us to define the reservoir continuities, which may in turn, determine the in-fill well locations. The proposed technique allows us to incorporate some of the production data as constraints in the reservoir descriptions. The technique has been validated by comparing the results with numerical simulations.

  7. World, We Have Problems: Simulation for Large Complex, Risky Projects, and Events

    NASA Technical Reports Server (NTRS)

    Elfrey, Priscilla

    2010-01-01

    Prior to a spacewalk during the NASA STS/129 mission in November 2009, Columbia Broadcasting System (CBS) correspondent William Harwood reported astronauts, "were awakened again", as they had been the day previously. Fearing something not properly connected was causing a leak, the crew, both on the ground and in space, stopped and checked everything. The alarm proved false. The crew did complete its work ahead of schedule, but the incident reminds us that correctly connecting hundreds and thousands of entities, subsystems and systems, finding leaks, loosening stuck valves, and adding replacements to very large complex systems over time does not occur magically. Everywhere major projects present similar pressures. Lives are at - risk. Responsibility is heavy. Large natural and human-created disasters introduce parallel difficulties as people work across boundaries their countries, disciplines, languages, and cultures with known immediate dangers as well as the unexpected. NASA has long accepted that when humans have to go where humans cannot go that simulation is the sole solution. The Agency uses simulation to achieve consensus, reduce ambiguity and uncertainty, understand problems, make decisions, support design, do planning and troubleshooting, as well as for operations, training, testing, and evaluation. Simulation is at the heart of all such complex systems, products, projects, programs, and events. Difficult, hazardous short and, especially, long-term activities have a persistent need for simulation from the first insight into a possibly workable idea or answer until the final report perhaps beyond our lifetime is put in the archive. With simulation we create a common mental model, try-out breakdowns of machinery or teamwork, and find opportunity for improvement. Lifecycle simulation proves to be increasingly important as risks and consequences intensify. Across the world, disasters are increasing. We anticipate more of them, as the results of global warming

  8. Predicting the severity of spurious "double ITCZ" problem in CMIP5 coupled models from AMIP simulations

    NASA Astrophysics Data System (ADS)

    Xiang, Baoqiang; Zhao, Ming; Held, Isaac M.; Golaz, Jean-Christophe

    2017-02-01

    The severity of the double Intertropical Convergence Zone (DI) problem in climate models can be measured by a tropical precipitation asymmetry index (PAI), indicating whether tropical precipitation favors the Northern Hemisphere or the Southern Hemisphere. Examination of 19 Coupled Model Intercomparison Project phase 5 models reveals that the PAI is tightly linked to the tropical sea surface temperature (SST) bias. As one of the factors determining the SST bias, the asymmetry of tropical net surface heat flux in Atmospheric Model Intercomparison Project (AMIP) simulations is identified as a skillful predictor of the PAI change from an AMIP to a coupled simulation, with an intermodel correlation of 0.90. Using tropical top-of-atmosphere (TOA) fluxes, the correlations are lower but still strong. However, the extratropical asymmetries of surface and TOA fluxes in AMIP simulations cannot serve as useful predictors of the PAI change. This study suggests that the largest source of the DI bias is from the tropics and from atmospheric models.

  9. Simulation of Detonation Problems with the MLS Grid-Free Methodology

    SciTech Connect

    Yao, J; Gunger, M E; Matuska, D A

    2002-08-27

    The Moving Least Squares (MLS) grid-free method, a simple, flexible finite difference method for solution of general continuum mechanics problems, especially detonation problems, is proposed in this paper. The spatial points that carry time dependent data are distributed in space in such a way that provides nearly uniform spacing of points, accurate presentation of boundaries, easy variation of resolution and arbitrary reorganization of the computational domain. Local finite difference operators are obtained with simple MLS differentiation. There is no specific topological or geometrical restriction of the distribution of data points. Therefore this method avoids many drawbacks of the traditional methods. Because of its flexibility, it can be used to simulate a wide range of mechanics problems. Because of its simplicity, it has the potential to become a preferred method. Most traditional computational continuum mechanics (CCM) methods, from a Smooth Particle Hydrodynamics (SPH) view, can be considered as special cases of grid-free methods of specific kernel functions. Such a generalization allows the development of a unified grid-free method that can represent most finite difference methods by switching the kernel functions. The flexible management and ease of coding make such a unified code attractive for many applications. A simple three-dimensional narrow-band level-set algorithm, which is associated with the MLS grid free data point distribution in three dimensions, is also proposed.

  10. A memory structure adapted simulated annealing algorithm for a green vehicle routing problem.

    PubMed

    Küçükoğlu, İlker; Ene, Seval; Aksoy, Aslı; Öztürk, Nursel

    2015-03-01

    Currently, reduction of carbon dioxide (CO2) emissions and fuel consumption has become a critical environmental problem and has attracted the attention of both academia and the industrial sector. Government regulations and customer demands are making environmental responsibility an increasingly important factor in overall supply chain operations. Within these operations, transportation has the most hazardous effects on the environment, i.e., CO2 emissions, fuel consumption, noise and toxic effects on the ecosystem. This study aims to construct vehicle routes with time windows that minimize the total fuel consumption and CO2 emissions. The green vehicle routing problem with time windows (G-VRPTW) is formulated using a mixed integer linear programming model. A memory structure adapted simulated annealing (MSA-SA) meta-heuristic algorithm is constructed due to the high complexity of the proposed problem and long solution times for practical applications. The proposed models are integrated with a fuel consumption and CO2 emissions calculation algorithm that considers the vehicle technical specifications, vehicle load, and transportation distance in a green supply chain environment. The proposed models are validated using well-known instances with different numbers of customers. The computational results indicate that the MSA-SA heuristic is capable of obtaining good G-VRPTW solutions within a reasonable amount of time by providing reductions in fuel consumption and CO2 emissions.

  11. SVD-GFD scheme to simulate complex moving body problems in 3D space

    NASA Astrophysics Data System (ADS)

    Wang, X. Y.; Yu, P.; Yeo, K. S.; Khoo, B. C.

    2010-03-01

    The present paper presents a hybrid meshfree-and-Cartesian grid method for simulating moving body incompressible viscous flow problems in 3D space. The method combines the merits of cost-efficient and accurate conventional finite difference approximations on Cartesian grids with the geometric freedom of generalized finite difference (GFD) approximations on meshfree grids. Error minimization in GFD is carried out by singular value decomposition (SVD). The Arbitrary Lagrangian-Eulerian (ALE) form of the Navier-Stokes equations on convecting nodes is integrated by a fractional-step projection method. The present hybrid grid method employs a relatively simple mode of nodal administration. Nevertheless, it has the geometrical flexibility of unstructured mesh-based finite-volume and finite element methods. Boundary conditions are precisely implemented on boundary nodes without interpolation. The present scheme is validated by a moving patch consistency test as well as against published results for 3D moving body problems. Finally, the method is applied on low-Reynolds number flapping wing applications, where large boundary motions are involved. The present study demonstrates the potential of the present hybrid meshfree-and-Cartesian grid scheme for solving complex moving body problems in 3D.

  12. Numerical simulation of low gravity draining. [computerized simulation of liquid sloshing in cylindrical tanks, and boundary value problems

    NASA Technical Reports Server (NTRS)

    Bizzell, G. D.; Crane, G. E.

    1976-01-01

    A boundary value problem was solved numerically for a liquid that is assumed to be inviscid and incompressible, having a motion that is irrotational and axisymmetric, and having a constant (5 degrees) solid-liquid contact angle. The avoidance of excessive mesh distortion, encountered with strictly Lagrangian or Eulerian kinematics, was achieved by introducing an auxiliary kinematic velocity field along the free surface in order to vary the trajectories used in integrating the ordinary differential equations simulating the moving boundary. The computation of the velocity potential was based upon a nonuniform triangular mesh which was automatically revised to varying depths to accommodate the motion of the free surface. These methods permitted calculation of draining induced axisymmetric slosh through the many (or fractional) finite amplitude oscillations that can occur depending upon the balance of draining, gravitational, and surface tension forces. Velocity fields, evolution of the free surface with time, and liquid residual volumes were computed for three and one half decades of Weber number and for two Bond numbers, tank fill levels, and drain radii. Comparisons with experimental data are very satisfactory.

  13. Simulation of the dissolved nitrogen and phosphorus loads in different land uses in the Three Gorges Reservoir Region--based on the improved export coefficient model.

    PubMed

    Wang, Jinliang; Shao, Jing'an; Wang, Dan; Ni, Jiupai; Xie, Deti

    2015-11-01

    Nonpoint source pollution is one of the primary causes of eutrophication of water bodies. The concentrations and loads of dissolved pollutants have a direct bearing on the environmental quality of receiving water bodies. Based on the Johnes export coefficient model, a pollutant production coefficient was established by introducing the topographical index and measurements of annual rainfall. A pollutant interception coefficient was constructed by considering the width and slope of present vegetation. These two coefficients were then used as the weighting factors to modify the existing export coefficients of various land uses. A modified export coefficient model was created to estimate the dissolved nitrogen and phosphorus loads in different land uses in the Three Gorges Reservoir Region (TGRR) in 1990, 1995, 2000, 2005, and 2010. The results show that the new land use export coefficient was established by the modification of the production pollution coefficient and interception pollution coefficient. This modification changed the single numerical structure of the original land use export coefficient and takes into consideration temporal and spatial differentiation features. The modified export coefficient retained the change structure of the original single land use export coefficient, and also demonstrated that the land use export coefficient was not only impacted by the change of land use itself, but was also influenced by other objective conditions, such as the characteristics of the underlying surface, amount of rainfall, and the overall presence of vegetation. In the five analyzed years, the simulation values of the dissolved nitrogen and phosphorus loads in paddy fields increased after applying the modification in calculation. The dissolved nitrogen and phosphorus loads in dry land comprised the largest proportions of the TGRR's totals. After modification, the dry land values showed an initial increase and then a decrease over time, but the increments were

  14. Can Multimedia Make Kids Care about Social Studies? The GlobalEd Problem-Based Learning Simulation

    ERIC Educational Resources Information Center

    Ioannou, Andri; Brown, Scott W.; Hannafin, Robert D.; Boyer, Mark A.

    2009-01-01

    This study investigated whether using multimedia-based instructional material in a problem-based social studies simulation enhances student learning about world issues, increases interest in social studies, and generates positive attitudes toward the instruction. The GlobalEd Project, a Web-based international negotiation simulation embedded in…

  15. Reservoir environment of the Onuma geothermal power plant, northeast Japan, estimated by forward analysis of long-term artificial-tracer concentration change, using single-box-model simulator

    SciTech Connect

    Shigeno, Hiroshi; Takahashi, Masaaki; Tetsuro, Noda

    1993-01-28

    A single-box-model numerical simulator for personal computer analysis was developed in order to estimate macroscopic parameter values for exploited geothermal reservoirs and essential fluids coming from the depth. The simulator was designed to compute history data concerning total production and reinjection fluids at geothermal power plants from the assumed parameter values, based on conservation laws for water mass, heat energy and masses of conservative chemical constituents of geothermal fluids. Using two kinds of forward analysis techniques, i.e. the cast-net and pursuit methods, programs containing the simulator can semiautomatically select the optimum combination of the unknown parameter values by minimizing the differences between the simulated and measured history data for specific enthalpy and chemical compositions of the production fluids. The forward analysis programs were applied to the history data from the Onuma geothermal power plant (production capacity, 10MWe) where waste hot water reinjection, chemical monitoring and artificial tracer tests have been conducted since 1970, almost the beginning of the geothermal exploitation. Using the history data, enthalpy and iodine concentrations of the total production fluids with the amounts of KI tracer injected as spikes, the macroscopic parameter values for the exploited reservoir and the essential hot water from the depth were uniquely determined as follows: mass of the hot water convecting in the exploited reservoir (M0), 3.23x109kg; recycling fraction of the reinjected waste hot water to the reservoir (R), 0.74; specific enthalpy of the essential water from the depth (H1), 385kcalkg; iodine concentration of the water (I1), 0.086mg/kg with chlorine concentration (C1), 259mg/kg. These results support the conceptual model that the exploited Onuma reservoir mainly in the Tertiary volcanics is supplied with the neutral Na-Cl type hot water of abnormally high B/CI mole ratio of around 1.0 by a large

  16. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    SciTech Connect

    Wiggins, Michael L.; Brown, Raymon L.; Civan, Faruk; Hughes, Richard G.

    2003-02-11

    This research was directed toward developing a systematic reservoir characterization methodology which can be used by the petroleum industry to implement infill drilling programs and/or enhanced oil recovery projects in naturally fractured reservoir systems in an environmentally safe and cost effective manner. It was anticipated that the results of this research program will provide geoscientists and engineers with a systematic procedure for properly characterizing a fractured reservoir system and a reservoir/horizontal wellbore simulator model which can be used to select well locations and an effective EOR process to optimize the recovery of the oil and gas reserves from such complex reservoir systems.

  17. Potential Impacts of Leakage from Black Rock Reservoir on the Hanford Site Unconfined Aquifer: Initial Hypothetical Simulations of Flow and Contaminant Transport - Errata

    SciTech Connect

    Freedman, Vicky L.

    2007-04-30

    Errata for report documenting initial scoping calculations investigating the potential impacts on the Hanford unconfined aquifer resulting from leakage from the proposed Black Rock Reservoir to the west. These calculations were performed for the U.S. Bureau of Reclamation.

  18. Problems Caused by Microbes and Treatment Strategies The Effect of Nitrate Injection in Oil Reservoirs - Experience with Nitrate Injection in the Halfdan Oilfield

    NASA Astrophysics Data System (ADS)

    Larsen, Jan; Skovhus, Torben Lund

    This chapter deals with the use of nitrate injection for reservoir souring mitigation in an oilfield with seawater injection in the Danish sector of the North Sea. Nitrate impacts on the activity of sulphate-reducing bacteria (SRB) and biofilm redox potential (Larsen et al., 2007), as a result of which corrosion due to SRB activity will be reduced, souring inhibited and previously formed sulphide removed (Larsen, 2002). One important aspect is that the microbiological reduction of nitrate provides approximately three times more energy to SRB than the reduction of sulphate. Therefore, when both nitrate and sulphate are present, nitrate becomes the preferred electron acceptor and SRB capable of growing on nitrate will dominate. Nitrate provides a competitive advantage to nitrate-utilising bacteria (indicated by the general acronym NUB) during competition for available carbon sources as the NUB are capable of much faster growth than SRB.

  19. Applications of weakly compressible model to turbulent flow problem towards adaptive turbulence simulation

    NASA Astrophysics Data System (ADS)

    Tsuji, Takuya; Yokomine, Takehiko; Shimizu, Akihiko

    2002-11-01

    We have been engaged in the development of multi-scale adaptive simulation technique for incompressible turbulent flow. This is designed as that important scale components in the flow field are detected automatically by lifting wavelet and solved selectively. In conventional incompressible scheme, it is very common to solve Poisson equation of pressure to meet the divergence free constraints of incompressible flow. It may be not impossible to solve the Poisson eq. in the adaptive way, but this is very troublesome because it requires generation of control volume at each time step. We gave an eye on weakly compressible model proposed by Bao(2001). This model was derived from zero Mach limit asymptotic analysis of compressible Navier-Stokes eq. and does not need to solve the Poisson eq. at all. But it is relatively new and it requires demonstration study before the combination with the adaptation by wavelet. In present study, 2-D and 3-D Backstep flow were selected as test problems and applicability to turbulent flow is verified in detail. Besides, combination of adaptation by wavelet with weakly compressible model towards the adaptive turbulence simulation is discussed.

  20. Filtering analysis of a direct numerical simulation of the turbulent Rayleigh-Benard problem

    NASA Technical Reports Server (NTRS)

    Eidson, T. M.; Hussaini, M. Y.; Zang, T. A.

    1990-01-01

    A filtering analysis of a turbulent flow was developed which provides details of the path of the kinetic energy of the flow from its creation via thermal production to its dissipation. A low-pass spatial filter is used to split the velocity and the temperature field into a filtered component (composed mainly of scales larger than a specific size, nominally the filter width) and a fluctuation component (scales smaller than a specific size). Variables derived from these fields can fall into one of the above two ranges or be composed of a mixture of scales dominated by scales near the specific size. The filter is used to split the kinetic energy equation into three equations corresponding to the three scale ranges described above. The data from a direct simulation of the Rayleigh-Benard problem for conditions where the flow is turbulent are used to calculate the individual terms in the three kinetic energy equations. This is done for a range of filter widths. These results are used to study the spatial location and the scale range of the thermal energy production, the cascading of kinetic energy, the diffusion of kinetic energy, and the energy dissipation. These results are used to evaluate two subgrid models typically used in large-eddy simulations of turbulence. Subgrid models attempt to model the energy below the filter width that is removed by a low-pass filter.

  1. Optimisation of decision making under uncertainty throughout field lifetime: A fractured reservoir example

    NASA Astrophysics Data System (ADS)

    Arnold, Dan; Demyanov, Vasily; Christie, Mike; Bakay, Alexander; Gopa, Konstantin

    2016-10-01

    Assessing the change in uncertainty in reservoir production forecasts over field lifetime is rarely undertaken because of the complexity of joining together the individual workflows. This becomes particularly important in complex fields such as naturally fractured reservoirs. The impact of this problem has been identified in previous and many solutions have been proposed but never implemented on complex reservoir problems due to the computational cost of quantifying uncertainty and optimising the reservoir development, specifically knowing how many and what kind of simulations to run. This paper demonstrates a workflow that propagates uncertainty throughout field lifetime, and into the decision making process by a combination of a metric-based approach, multi-objective optimisation and Bayesian estimation of uncertainty. The workflow propagates uncertainty estimates from appraisal into initial development optimisation, then updates uncertainty through history matching and finally propagates it into late-life optimisation. The combination of techniques applied, namely the metric approach and multi-objective optimisation, help evaluate development options under uncertainty. This was achieved with a significantly reduced number of flow simulations, such that the combined workflow is computationally feasible to run for a real-field problem. This workflow is applied to two synthetic naturally fractured reservoir (NFR) case studies in appraisal, field development, history matching and mid-life EOR stages. The first is a simple sector model, while the second is a more complex full field example based on a real life analogue. This study infers geological uncertainty from an ensemble of models that are based on the carbonate Brazilian outcrop which are propagated through the field lifetime, before and after the start of production, with the inclusion of production data significantly collapsing the spread of P10-P90 in reservoir forecasts. The workflow links uncertainty

  2. SimPEG: An open-source framework for geophysical simulations and inverse problems

    NASA Astrophysics Data System (ADS)

    Cockett, R.; Kang, S.; Heagy, L.

    2014-12-01

    Geophysical surveys are powerful tools for obtaining information about the subsurface. Inverse modelling provides a mathematical framework for constructing a model of physical property distributions that are consistent with the data collected by these surveys. The geosciences are increasingly moving towards the integration of geological, geophysical, and hydrological information to better characterize the subsurface. This integration must span disciplines and is not only challenging scientifically, but the inconsistencies between conventions often makes implementations complicated, non-reproducible, or inefficient. We have developed an open source software package for Simulation and Parameter Estimation in Geophysics (SimPEG), which provides a generalized framework for solving geophysical forward and inverse problems. SimPEG is written entirely in Python with minimal dependencies in the hopes that it can be used both as a research tool and for education. SimPEG includes finite volume discretizations on structured and unstructured meshes, interfaces to standard numerical solver packages, convex optimization algorithms, model parameterizations, and tailored visualization routines. The framework is modular and object-oriented, which promotes real time experimentation and combination of geophysical problems and inversion methodologies. In this presentation, we will highlight a few geophysical examples, including direct-current resistivity and electromagnetics, and discuss some of the challenges and successes we encountered in developing a flexible and extensible framework. Throughout development of SimPEG we have focused on simplicity, usability, documentation, and extensive testing. By embracing a fully open source development paradigm, we hope to encourage reproducible research, cooperation, and communication to help tackle some of the inherently multidisciplinary problems that face integrated geophysical methods.

  3. Majorana-Time-Reversal Symmetries: A Fundamental Principle for Sign-Problem-Free Quantum Monte Carlo Simulations

    NASA Astrophysics Data System (ADS)

    Li, Zi-Xiang; Jiang, Yi-Fan; Yao, Hong

    2016-12-01

    A fundamental open issue in physics is whether and how the fermion sign problem in quantum Monte Carlo (QMC) simulations can be solved generically. Here, we show that Majorana-time-reversal (MTR) symmetries can provide a unifying principle to solve the fermion sign problem in interacting fermionic models. By systematically classifying Majorana-bilinear operators according to the anticommuting MTR symmetries they respect, we rigorously prove that there are two and only two fundamental symmetry classes which are sign-problem-free and which we call the "Majorana class" and "Kramers class," respectively. Novel sign-problem-free models in the Majorana class include interacting topological superconductors and interacting models of charge-4 e superconductors. We believe that our MTR unifying principle could shed new light on sign-problem-free QMC simulation on strongly correlated systems and interacting topological matters.

  4. Uncertainty analysis for water supply reservoir yields

    NASA Astrophysics Data System (ADS)

    Kuria, Faith; Vogel, Richard

    2015-10-01

    Understanding the variability of water supply reservoir yields is central for planning purposes. The basis of this study is an empirical global relationship between reservoir storage capacity, water supply yield and reliability based on a global database of 729 rivers. Monte Carlo simulations reveal that the coefficient of variation of estimates of water supply reservoir yields depend only on the length of streamflows record and the coefficient of variation of the streamflows used to estimate the yield. We compare the results of those Monte Carlo experiments with an analytical uncertainty method First Order Variance Approximation (FOVA). FOVA is shown to produce a general, accurate and useful expression for estimating the coefficient of variation of water supply reservoir yield estimates. We also document how the FOVA analytical model can be used to determine the minimum length of streamflow record required during the design of water supply reservoirs so as to ensure that the yield delivered from reservoir falls within a prespecified margin of error.

  5. Sprocket- Chain Simulation: Modelling and Simulation of a Multi Physics problem by sequentially coupling MotionSolve and nanoFluidX

    NASA Astrophysics Data System (ADS)

    Jayanthi, Aditya; Coker, Christopher

    2016-11-01

    In the last decade, CFD simulations have transitioned from the stage where they are used to validate the final designs to the main stream development of products driven by the simulation. However, there are still niche areas of applications liking oiling simulations, where the traditional CFD simulation times are probative to use them in product development and have to rely on experimental methods, which are expensive. In this paper a unique example of Sprocket-Chain simulation will be presented using nanoFluidx a commercial SPH code developed by FluiDyna GmbH and Altair Engineering. The grid less nature of the of SPH method has inherent advantages in the areas of application with complex geometry which pose severe challenge to classical finite volume CFD methods due to complex moving geometries, moving meshes and high resolution requirements leading to long simulation times. The simulations times using nanoFluidx can be reduced from weeks to days allowing the flexibility to run more simulation and can be in used in main stream product development. The example problem under consideration is a classical Multiphysics problem and a sequentially coupled solution of Motion Solve and nanoFluidX will be presented. This abstract is replacing DFD16-2016-000045.

  6. Increasing heavy oil reservers in the Wilmington oil Field through advanced reservoir characterization and thermal production technologies, technical progress report, October 1, 1996--December 31, 1996

    SciTech Connect

    Hara, S. , Casteel, J.

    1997-05-11

    The project involves improving thermal recovery techniques in a slope and basin clastic (SBC) reservoir in the Wilmington field, Los Angeles Co., Calif. using advanced reservoir characterization and thermal production technologies. The existing steamflood in the Tar zone of Fault Block (FB) 11-A has been relatively inefficient because of several producibility problems which are common in SBC reservoirs. Inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil, and nonuniform distribution of remaining oil have all contributed to poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated formation sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. The advanced technologies to be applied include: (1) Develop three-dimensional (3-D) deterministic and stochastic geologic models. (2) Develop 3-D deterministic and stochastic thermal reservoir simulation models to aid in reservoir management and subsequent development work. (3) Develop computerized 3-D visualizations of the geologic and reservoir simulation models to aid in analysis. (4) Perform detailed study on the geochemical interactions between the steam and the formation rock and fluids. (5) Pilot steam injection and production via four new horizontal wells (2 producers and 2 injectors). (6) Hot water alternating steam (WAS) drive pilot in the existing steam drive area to improve thermal efficiency. (7) Installing a 2100 foot insulated, subsurface harbor channel crossing to supply steam to an island location. (8) Test a novel alkaline steam completion technique to control well sanding problems and fluid entry profiles. (9) Advanced reservoir management through computer-aided access to production and

  7. Expansion of flight simulator capability for study and solution of aircraft directional control problems on runways

    NASA Technical Reports Server (NTRS)

    Kibbee, G. W.

    1978-01-01

    The development, evaluation, and evaluation results of a DC-9-10 runway directional control simulator are described. An existing wide bodied flight simulator was modified to this aircraft configuration. The simulator was structured to use either two of antiskid simulations; (1) an analog mechanization that used aircraft hardware; or (2) a digital software simulation. After the simulation was developed it was evaluated by 14 pilots who made 818 simulated flights. These evaluations involved landings, rejected takeoffs, and various ground maneuvers. Qualitatively most pilots evaluated the simulator as realistic with good potential especially for pilot training for adverse runway conditions.

  8. Prescriptive Reservoir System Analysis Model - Missouri River System Application

    DTIC Science & Technology

    1991-11-01

    identical to those used with the reservoir simulation model in use by the Corps Missouri River l)ivision (MRI)), applied to the same period. Composite...8217l’o test the reasonableness of’ the rusults, IIE(-PI{M results were compared with those ofthe MRI) reservoir simulation model. This comparison is...34Multi- reservoir simulation and optimization model SIM-V," UM-38, Texas Department of Water Resources, Austin, TX. U.S. Army Corps of Engineers

  9. How common problems with estimating surface radiative fluxes impact snow simulations

    NASA Astrophysics Data System (ADS)

    Lapo, K. E.; Lundquist, J. D.; Hinkelman, L. M.

    2012-12-01

    Net radiation provides most of the melt energy for seasonal snow, a critical water resource for many parts of the world. In many cases shortwave radiation is the dominant flux, but when it is reduced by factors such as high albedo, cloud cover, and topographic shading, longwave radiation can also contribute substantially to the surface energy balance. Methods for determining these surface fluxes include: numerical weather models, reanalysis, direct observations, satellite measurements, and empirical algorithms based on proxy data. Long- and shortwave irradiances are rarely measured in mountainous environments. Those measurements that are made in these locations are subject to difficult conditions, which often result in snow-covered instruments and tilted instrumentation or sloped installation surface. To avoid these problems, measurements may be taken from a more protected valley location, but this may lead to a mismatch between measurement and study site conditions, such as a fog covered valley observation used to force a simulation at a higher, fog-free elevation. Satellites are useful tools for observing surface fluxes over large areas. However, satellite data products can have problems with mixed pixels of clouds and no clouds. Finally, algorithms based on proxy data have known biases and errors, can lack cloud and topographic corrections, and may not represent the diurnal cycle or cloud cover variability. In this study, we explored four scenarios for estimating long- and shortwave surface irradiances that have known errors and assessed the impact of these errors on simulations of SWE. The four scenarios were: 1) improper instrument siting such as a tilted sensor or improper projection of observations onto sloped terrain, 2) biases and errors in surface irradiances characteristic of algorithms based on proxy data, 3) mixed pixels of cloudy and non-cloudy conditions resulting from a coarse spatial resolution in a satellite or reanalysis product, and 4) lack of

  10. Simulations of dusty plasmas using a special-purpose computer system designed for gravitational N-body problems

    SciTech Connect

    Yamamoto, K.; Mizuno, Y.; Hibino, S.; Inuzuka, H.; Cao, Y.; Liu, Y.; Yazawa, K.

    2006-01-15

    Simulations of dusty plasmas were performed using GRAPE-6, a special-purpose computer designed for gravitational N-body problems. The collective behavior of dust particles, which are injected into the plasma, was studied by means of three-dimensional computer simulations. As an example of a dusty plasma simulation, experiments on Coulomb crystals in plasmas are simulated. Formation of a quasi-two-dimensional Coulomb crystal has been observed under typical laboratory conditions. Another example was to simulate movement of dust particles in plasmas under microgravity conditions. Fully three-dimensional spherical structures of dust clouds have been observed. For the simulation of a dusty plasma in microgravity with 3x10{sup 4} particles, GRAPE-6 can perform the whole operation 1000 times faster than by using a Pentium 4 1.6 GHz processor.

  11. Validation of a Pressure-Based Combustion Simulation Tool Using a Single Element Injector Test Problem

    NASA Technical Reports Server (NTRS)

    Thakur, Siddarth; Wright, Jeffrey

    2006-01-01

    The traditional design and analysis practice for advanced propulsion systems, particularly chemical rocket engines, relies heavily on expensive full-scale prototype development and testing. Over the past decade, use of high-fidelity analysis and design tools such as CFD early in the product development cycle has been identified as one way to alleviate testing costs and to develop these devices better, faster and cheaper. Increased emphasis is being placed on developing and applying CFD models to simulate the flow field environments and performance of advanced propulsion systems. This necessitates the development of next generation computational tools which can be used effectively and reliably in a design environment by non-CFD specialists. A computational tool, called Loci-STREAM is being developed for this purpose. It is a pressure-based, Reynolds-averaged Navier-Stokes (RANS) solver for generalized unstructured grids, which is designed to handle all-speed flows (incompressible to hypersonic) and is particularly suitable for solving multi-species flow in fixed-frame combustion devices. Loci-STREAM integrates proven numerical methods for generalized grids and state-of-the-art physical models in a novel rule-based programming framework called Loci which allows: (a) seamless integration of multidisciplinary physics in a unified manner, and (b) automatic handling of massively parallel computing. The objective of the ongoing work is to develop a robust simulation capability for combustion problems in rocket engines. As an initial step towards validating this capability, a model problem is investigated in the present study which involves a gaseous oxygen/gaseous hydrogen (GO2/GH2) shear coaxial single element injector, for which experimental data are available. The sensitivity of the computed solutions to grid density, grid distribution, different turbulence models, and different near-wall treatments is investigated. A refined grid, which is clustered in the vicinity of

  12. Understanding Microbial Reservoir Souring and Desouring Processes Using Reactive Transport Modeling

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Bouskill, N.; Hubbard, C. G.; Hubbard, S. S.; Ajo Franklin, J. B.; Li, L.; Engelbrektson, A. L.; Coates, J. D.; Surasani, V.

    2013-12-01

    Microbial sulfate reduction is the major metabolic process that leads to oil reservoir souring. Souring typically occurs when (sea)water is injected into the oil reservoir to maintain pressure and sweep remnant oil through the reservoir. Because biogenesis of hydrogen sulfide has detrimental impacts on oil production operations and can cause significant environmental and health problems, we strive to develop predictive understanding of reservoir souring and associated mitigation processes. Recent laboratory sediment column experiments have demonstrated the effectiveness of nitrate, chlorate and perchlorate treatments as souring control strategies. In this study, we describe the development of a reactive transport model that is based on the reaction mechanisms and kinetics revealed through the column experimental data. The model was used to simulate the temporal and spatial evolution of the primary chemical species (e.g. sulfate, sulfide, nitrate, chlorate and perchlorate) and the microbial dynamics involved in the souring and desouring processes. The growth and inhibition dynamics of the sulfate reducing bacterial population are explicitly simulated and constrained by energetics. Simulation of the laboratory experimental results show that the model captured the spatio-temporal trend of the chemical species and microbial guilds during both souring and desouring. Ongoing research is focusing on extending the reactive transport model to mechanistically understand, quantify, and predict souring and desouring processes within heterogeneous reservoirs as a step toward optimizing field scale souring control strategies.

  13. Examining the accuracy of astrophysical disk simulations with a generalized hydrodynamical test problem [The role of pressure and viscosity in SPH simulations of astrophysical disks

    SciTech Connect

    Raskin, Cody; Owen, J. Michael

    2016-10-24

    Here, we discuss a generalization of the classic Keplerian disk test problem allowing for both pressure and rotational support, as a method of testing astrophysical codes incorporating both gravitation and hydrodynamics. We argue for the inclusion of pressure in rotating disk simulations on the grounds that realistic, astrophysical disks exhibit non-negligible pressure support. We then apply this test problem to examine the performance of various smoothed particle hydrodynamics (SPH) methods incorporating a number of improvements proposed over the years to address problems noted in modeling the classical gravitation-only Keplerian disk. We also apply this test to a newly developed extension of SPH based on reproducing kernels called CRKSPH. Counterintuitively, we find that pressure support worsens the performance of traditional SPH on this problem, causing unphysical collapse away from the steady-state disk solution even more rapidly than the purely gravitational problem, whereas CRKSPH greatly reduces this error.

  14. Examining the accuracy of astrophysical disk simulations with a generalized hydrodynamical test problem [The role of pressure and viscosity in SPH simulations of astrophysical disks

    DOE PAGES

    Raskin, Cody; Owen, J. Michael

    2016-10-24

    Here, we discuss a generalization of the classic Keplerian disk test problem allowing for both pressure and rotational support, as a method of testing astrophysical codes incorporating both gravitation and hydrodynamics. We argue for the inclusion of pressure in rotating disk simulations on the grounds that realistic, astrophysical disks exhibit non-negligible pressure support. We then apply this test problem to examine the performance of various smoothed particle hydrodynamics (SPH) methods incorporating a number of improvements proposed over the years to address problems noted in modeling the classical gravitation-only Keplerian disk. We also apply this test to a newly developed extensionmore » of SPH based on reproducing kernels called CRKSPH. Counterintuitively, we find that pressure support worsens the performance of traditional SPH on this problem, causing unphysical collapse away from the steady-state disk solution even more rapidly than the purely gravitational problem, whereas CRKSPH greatly reduces this error.« less

  15. Seismic monitoring of heavy oil reservoirs: Rock physics and finite element modelling

    NASA Astrophysics Data System (ADS)

    Theune, Ulrich

    In the past decades, remote monitoring of subsurface processes has attracted increasing attention in geophysics. With repeated geophysical surveys one attempts to detect changes in the physical properties in the underground without directly accessing the earth. This technique has been proven to be very valuable for monitoring enhanced oil recovery programs. This thesis presents an modelling approach for the feasibility analysis for monitoring of a thermal enhanced oil recovery technique applied to heavy oil reservoirs in the Western Canadian Sedimentary Basin. In order to produce heavy oil from shallow reservoirs thermal oil recovery techniques such as the Steam Assisted Gravity Drainage (SAGD) are often employed. As these techniques are expensive and technically challenging, early detection of operational problems is without doubt of great value. However, the feasibility of geophysical monitoring depends on many factors such as the changes in the rock physical properties of the target reservoir. In order to access the feasibility of seismic monitoring for heavy oil reservoirs, a fluid-substitutional rock physical study has been carried out to simulate the steam injection. The second modelling approach is based on a modified finite element algorithm to simulate the propagation of elastic waves in the earth, which has been developed independently in the framework of this thesis. The work summarized in this thesis shows a possibility to access the feasibility of seismic monitoring for heavy oil reservoirs through an extensive rock-physical study. Seismic monitoring is a useful tool in reservoir management decision process. However, the work reported here suggests that seismic monitoring of SAGD processes in the heavy oil reservoirs of the Western Canadian Sedimentary Basin is only feasible in shallow, unconsolidated deposits. For deeper, but otherwise geological similar reservoirs, the SAGD does not create a sufficient change in the rock physical properties to be

  16. Water coning in porous media reservoirs for compressed air energy storage

    SciTech Connect

    Wiles, L.E.; McCann, R.A.

    1981-06-01

    The general purpose of this work is to define the hydrodynamic and thermodynamic response of a CAES porous media reservoir subjected to simulated air mass cycling. This research will assist in providing design guidelines for the efficient and stable operation of the air storage reservoir. This report presents the analysis and results for the two-phase (air-water), two-dimensional, numerical modeling of CAES porous media reservoirs. The effects of capillary pressure and relative permeability were included. The fluids were considered to be immisicible; there was no phase change; and the system was isothermal. The specific purpose of this analysis was to evaluate the reservoir parameters that were believed to be important to water coning. This phenomenon may occur in reservoirs in which water underlies the air storage zone. It involves the possible intrusion of water into the wellbore or near-wellbore region. The water movement is in response to pressure gradients created during a reservoir discharge cycle. Potential adverse effects due to this water movement are associated with the pressure response of the reservoir and the geochemical stability of the near-wellbore region. The results obtained for the simulated operation of a CAES reservoir suggest that water coning should not be a severe problem, due to the slow response of the water to the pressure gradients and the relatively short duration in which those gradients exist. However, water coning will depend on site-specific conditions, particularly the fluid distributions following bubble development, and, therefore, a water coning analysis should be included as part of site evaluation.

  17. Reservoir technology research at the Idaho National Engineering Laboratory

    SciTech Connect

    Stiger, S.G.; Renner, J.L.

    1987-01-01

    The Idaho National Engineering Laboratory (INEL) has been conducting geothermal reservoir research and testing sponsored by the US Department of Energy (DOE) since 1983. The INEL research program is primarily aimed at the development of reservoir engineering techniques for fractured geothermal reservoirs. Numerical methods have been developed which allow the simulation of fluid flow and heat transfer in complex fractured reservoirs. Sensitivity studies have illustrated the importance of incorporating the influence of fractures in reservoir simulations. Related efforts include fracture characterization, geochemical reaction kinetics and field testing.

  18. Gaussian variational ansatz in the problem of anomalous sea waves: Comparison with direct numerical simulation

    SciTech Connect

    Ruban, V. P.

    2015-05-15

    The nonlinear dynamics of an obliquely oriented wave packet on a sea surface is analyzed analytically and numerically for various initial parameters of the packet in relation to the problem of the so-called rogue waves. Within the Gaussian variational ansatz applied to the corresponding (1+2)-dimensional hyperbolic nonlinear Schrödinger equation (NLSE), a simplified Lagrangian system of differential equations is derived that describes the evolution of the coefficients of the real and imaginary quadratic forms appearing in the Gaussian. This model provides a semi-quantitative description of the process of nonlinear spatiotemporal focusing, which is one of the most probable mechanisms of rogue wave formation in random wave fields. The system of equations is integrated in quadratures, which allows one to better understand the qualitative differences between linear and nonlinear focusing regimes of a wave packet. Predictions of the Gaussian model are compared with the results of direct numerical simulation of fully nonlinear long-crested waves.

  19. Gaussian variational ansatz in the problem of anomalous sea waves: Comparison with direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Ruban, V. P.

    2015-05-01

    The nonlinear dynamics of an obliquely oriented wave packet on a sea surface is analyzed analytically and numerically for various initial parameters of the packet in relation to the problem of the so-called rogue waves. Within the Gaussian variational ansatz applied to the corresponding (1+2)-dimensional hyperbolic nonlinear Schrödinger equation (NLSE), a simplified Lagrangian system of differential equations is derived that describes the evolution of the coefficients of the real and imaginary quadratic forms appearing in the Gaussian. This model provides a semi-quantitative description of the process of nonlinear spatiotemporal focusing, which is one of the most probable mechanisms of rogue wave formation in random wave fields. The system of equations is integrated in quadratures, which allows one to better understand the qualitative differences between linear and nonlinear focusing regimes of a wave packet. Predictions of the Gaussian model are compared with the results of direct numerical simulation of fully nonlinear long-crested waves.

  20. Nuclear EMP simulation for large-scale urban environments. FDTD for electrically large problems.

    SciTech Connect

    Smith, William S.; Bull, Jeffrey S.; Wilcox, Trevor; Bos, Randall J.; Shao, Xuan-Min; Goorley, John T.; Costigan, Keeley R.

    2012-08-13

    In case of a terrorist nuclear attack in a metropolitan area, EMP measurement could provide: (1) a prompt confirmation of the nature of the explosion (chemical or nuclear) for emergency response; and (2) and characterization parameters of the device (reaction history, yield) for technical forensics. However, urban environment could affect the fidelity of the prompt EMP measurement (as well as all other types of prompt measurement): (1) Nuclear EMP wavefront would no longer be coherent, due to incoherent production, attenuation, and propagation of gamma and electrons; and (2) EMP propagation from source region outward would undergo complicated transmission, reflection, and diffraction processes. EMP simulation for electrically-large urban environment: (1) Coupled MCNP/FDTD (Finite-difference time domain Maxwell solver) approach; and (2) FDTD tends to be limited to problems that are not 'too' large compared to the wavelengths of interest because of numerical dispersion and anisotropy. We use a higher-order low-dispersion, isotropic FDTD algorithm for EMP propagation.

  1. Incorporating reservoir heterogeneity with geostatistics to investigate waterflood recoveries

    SciTech Connect

    Wolcott, D.S. ); Chopra, A.K. )

    1993-03-01

    This paper presents an investigation of infill drilling performance and reservoir continuity with geostatistics and a reservoir simulator. The geostatistical technique provides many possible realizations and realistic descriptions of reservoir heterogeneity. Correlation between recovery efficiency and thickness of individual sand subunits is shown. Additional recovery from infill drilling results from thin, discontinuous subunits. The technique may be applied to variations in continuity for other sandstone reservoirs.

  2. Can physical joint simulators be used to anticipate clinical wear problems of new joint replacement implants prior to market release?

    PubMed

    Medley, John B

    2016-05-01

    One of the most important mandates of physical joint simulators is to provide test results that allow the implant manufacturer to anticipate and perhaps avoid clinical wear problems with their new products. This is best done before market release. This study gives four steps to follow in conducting such wear simulator testing. Two major examples involving hip wear simulators are discussed in which attempts had been made to predict clinical wear performance prior to market release. The second one, involving the DePuy ASR implant systems, is chosen for more extensive treatment by making it an illustrative example to explore whether wear simulator testing can anticipate clinical wear problems. It is concluded that hip wear simulator testing did provide data in the academic literature that indicated some risk of clinical wear problems prior to market release of the ASR implant systems. This supports the idea that physical joint simulators have an important role in the pre-market testing of new joint replacement implants.

  3. Flow Characterization in Naturally Fractured Reservoirs

    NASA Astrophysics Data System (ADS)

    Alajmi, A.; Gharbi, R.

    2008-12-01

    Most hydrocarbon reservoirs are fractured in nature with various degrees of fracture intensities. With the current oil prices and growing demand for oil, a great interest is built in the petroleum industry to characterize partially fractured reservoirs and to develop an increased understanding of the physics of fluid flow in these types of reservoirs. This is due to the fact that fractured reservoirs have different performance behavior and high potential for oil recovery than conventional reservoirs. Therefore, prediction and understanding of fluid displacement in these reservoirs is very much critical in the decision on the applicability of oil recovery methods. Using a finite difference numerical simulator, this study investigated the effect of reservoir fracture intensities on the displacement behavior. Several heterogeneous permeable media, each with different probability of fracture intensity, were generated stochastically. The fracture intensity covers reservoirs with no fracture (zero fracture intensity) to fully fractured reservoirs (fracture intensity of 1). In order to better describe and model fractured reservoirs, a dual porosity-dual permeability model was built. Extensive simulations of water displacing oil were then performed in each of the generated fractured models for different well configurations. The objective was to determine the functional relationships between the displacement performance, fracture intensities, and well configurations. The study has resulted in significant new insights into the flow characterization in naturally fractured reservoirs. Results show that the reservoir fracture intensity has considerable effects on the efficiency of fluid displacement in naturally fractured reservoirs. A critical value of reservoir fracture intensity appears to sort favorable from unfavorable displacement, causing the displacement to be either fracture-dominated or matrix-dominated. The conditions under which fluid displacement may yield better

  4. Integrated management of multiple reservoir field developments

    SciTech Connect

    Lyons, S.L.; Chan, H.M.; Harper, J.L.; Boyett, B.A.; Dowson, P.R.; Bette, S.

    1995-10-01

    This paper consists of two sections. The authors first describe the coupling of a pipeline network model to a reservoir simulator and then the application of this new simulator to optimize the production strategy of two Mobil field developments. Mobil`s PEGASUS simulator is an integrated all purpose reservoir simulator that handles black-oil, compositional, faulted and naturally fractured reservoirs. The authors have extended the simulator to simultaneously model multiple reservoirs coupled with surface pipeline networks and processes. This allows them to account for the effects of geology, well placement, and surface production facilities on well deliverability in a fully integrated fashion. They have also developed a gas contract allocation system that takes the user-specified constraints, target rates and swing factors and automatically assigns rates to the individual wells of each reservoir. This algorithm calculates the overall deliverability and automatically reduces the user-specified target rates to meet the deliverability constraints. The algorithm and solution technique are described. This enhanced simulator has been applied to model a Mobil field development in the Southern Gas Basin, offshore United Kingdom, which consists of three separate gas reservoirs connected via a pipeline network. The simulator allowed the authors to accurately determine the impact on individual reservoir and total field performance by varying the development timing of these reservoirs. Several development scenarios are shown to illustrate the capabilities of PEGASUS. Another application of this technology is in the field developments in North Sumatra, Indonesia. Here the objective is to economically optimize the development of multiple fields to feed the PT Arun LNG facility. Consideration of a range of gas compositions, well productivity`s, and facilities constraints in an integrated fashion results in improved management of these assets. Model specifics are discussed.

  5. Application of integrated reservoir management and reservoir characterization to optimize infill drilling. Quarterly technical progress report, March 13--June 12, 1997

    SciTech Connect

    1997-12-31

    The eighteen 10-acre infill wells which were drilled as part of the field demonstration portion of the project are all currently in service with no operational problems. These wells consist of fourteen producing wells and four injection wells. The producing wells are currently producing a total of approximately 650 bopd, down from a peak rate of 900 bopd. Unit production is currently averaging approximately 3,000 bopd, 12,000 bwpd and 18,000 bwipd. The paper describes progress in core analysis, reservoir surveillance, well stimulation, validation of reservoir characterization (includes thin section analyses, depositional environments, and paleontologic analysis), material balance decline curve analysis, and validation of reservoir simulation (includes geostatistical and deterministic).

  6. Training Students to Analyze Spatial and Temporal Heterogeneities in Reservoir and Seal Petrology, Mineralogy, and Geochemistry: Implications for CO{sub 2} Sequestration Prediction, Simulation, and Monitoring

    SciTech Connect

    Bowen, Brenda

    2013-09-30

    The objective of this project was to expose and train multiple students in geological tools that are essential to reservoir characterization and geologic sequestration including but not limited to advanced petrological methods, mineralogical methods, and geochemical methods; core analysis, and geophysical well-log interpretation. These efforts have included training of multiple students through geologically based curriculum and research using advanced petrological, mineralogical, and geochemical methods. In whole, over the last 3+ years, this award has supported 5,828 hours of student research, supporting the work of several graduate and undergraduate students. They have all received training directly related to ongoing CO{sub 2} sequestration demonstrations. The students have all conducted original scientific research on topics related to understanding the importance of lithological, textural, and compositional variability in formations that are being targeted as CO{sub 2} sequestration reservoirs and seals. This research was linked to the Mount Simon Sandstone reservoir and overlying Eau Claire Formation seal in the Illinois Basin- a system where over one million tons of CO{sub 2} are actively being injected with the first large-scale demonstration of anthropogenic CO{sub 2} storage in the U.S. Student projects focused specifically on 1) reservoir porosity characterization and evaluation, 2) petrographic, mineralogical, and geochemical evidence of fluid-related diagenesis in the caprock, 3) textural changes in reservoir samples exposed to experimental CO{sub 2} + brine conditions, 4) controls on spatial heterogeneity in composition and texture in both the reservoir and seal, 5) the implications of small-scale fractures within the reservoir, and 6) petrographic and stable isotope analyses of carbonates in the seal to understand the burial history of the system. The student-led research associated with this project provided real-time and hands-on experience with a

  7. Numerical modeling of water injection into vapor-dominatedgeothermal reservoirs

    SciTech Connect

    Pruess, Karsten

    2006-11-06

    Water injection has been recognized as a powerful techniquefor enhancing energy recovery from vapor-dominated geothermal systemssuch as The Geysers. In addition to increasing reservoir pressures,production well flow rates, and long-term sustainability of steamproduction, injection has also been shown to reduce concentrations ofnon-condensible gases (NCGs) in produced steam. The latter effectimproves energy conversion efficiency and reduces corrosion problems inwellbores and surface lines.This report reviews thermodynamic andhydrogeologic conditions and mechanisms that play an important role inreservoir response to water injection. An existing general-purposereservoir simulator has been enhanced to allow modeling of injectioneffects in heterogeneous fractured reservoirs in three dimensions,including effects of non-condensible gases of different solubility.Illustrative applications demonstrate fluid flow and heat transfermechanisms that are considered crucial for developing approaches to insitu abatement of NCGs.

  8. Electromagnetic Heating Methods for Heavy Oil Reservoirs

    SciTech Connect

    Sahni, A.; Kumar, M.; Knapp, R.B.

    2000-05-01

    The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. They present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency). They show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. They model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case they use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. They identify the parameters which are critical in electromagnetic heating. They also discuss past field applications of electromagnetic heating including technical challenges and limitations.

  9. Problem-based learning using patient-simulated videos showing daily life for a comprehensive clinical approach

    PubMed Central

    Ohira, Yoshiyuki; Uehara, Takanori; Noda, Kazutaka; Suzuki, Shingo; Shikino, Kiyoshi; Kajiwara, Hideki; Kondo, Takeshi; Hirota, Yusuke; Ikusaka, Masatomi

    2017-01-01

    Objectives We examined whether problem-based learning tutorials using patient-simulated videos showing daily life are more practical for clinical learning, compared with traditional paper-based problem-based learning, for the consideration rate of psychosocial issues and the recall rate for experienced learning. Methods Twenty-two groups with 120 fifth-year students were each assigned paper-based problem-based learning and video-based problem-based learning using patient-simulated videos. We compared target achievement rates in questionnaires using the Wilcoxon signed-rank test and discussion contents diversity using the Mann-Whitney U test. A follow-up survey used a chi-square test to measure students’ recall of cases in three categories: video, paper, and non-experienced. Results Video-based problem-based learning displayed significantly higher achievement rates for imagining authentic patients (p=0.001), incorporating a comprehensive approach including psychosocial aspects (p<0.001), and satisfaction with sessions (p=0.001). No significant differences existed in the discussion contents diversity regarding the International Classification of Primary Care Second Edition codes and chapter types or in the rate of psychological codes. In a follow-up survey comparing video and paper groups to non-experienced groups, the rates were higher for video (χ2=24.319, p<0.001) and paper (χ2=11.134, p=0.001). Although the video rate tended to be higher than the paper rate, no significant difference was found between the two. Conclusions Patient-simulated videos showing daily life facilitate imagining true patients and support a comprehensive approach that fosters better memory. The clinical patient-simulated video method is more practical and clinical problem-based tutorials can be implemented if we create patient-simulated videos for each symptom as teaching materials.  PMID:28245193

  10. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    SciTech Connect

    Wiggins, Michael L.; Brown, Raymon L.; Civan, Frauk; Hughes, Richard G.

    2001-08-15

    Research continues on characterizing and modeling the behavior of naturally fractured reservoir systems. Work has progressed on developing techniques for estimating fracture properties from seismic and well log data, developing naturally fractured wellbore models, and developing a model to characterize the transfer of fluid from the matrix to the fracture system for use in the naturally fractured reservoir simulator.

  11. Status of Norris Reservoir

    SciTech Connect

    Not Available

    1990-09-01

    This is one in a series of reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Norris Reservoir summarizes reservoir and watershed characteristics, reservoir uses, conditions that impair reservoir uses, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most up-to-date publications and data available, and from interviews with water resource professionals in various federal, state, and local agencies, and in public and private water supply and wastewater treatment facilities. 14 refs., 3 figs.

  12. A Problem-Based Learning Approach to Civics Education: Exploring the Free Exercise Clause with Supreme Court Simulations

    ERIC Educational Resources Information Center

    Pagnotti, John; Russell, William B., III

    2015-01-01

    The purpose of this article is to empower those interested in teaching students powerful and engaging social studies. Through the lens of Supreme Court simulations, this article provides educators with a viable, classroom-tested lesson plan to bring Problem-Based Learning into their classrooms. The specific aim of the lesson is to provide students…

  13. Simulating Results of Experiments on Gene Regulation of the Lactose Operon in Escherichia coli; a Problem-Solving Exercise.

    ERIC Educational Resources Information Center

    Hitchen, Trevor; Metcalfe, Judith

    1987-01-01

    Describes a simulation of the results of real experiments which use different strains of Escherichia coli. Provides an inexpensive practical problem-solving exercise to aid the teaching and understanding of the Jacob and Monod model of gene regulation. (Author/CW)

  14. Simulation-Based Medical Education Is No Better than Problem-Based Discussions and Induces Misjudgment in Self-Assessment

    ERIC Educational Resources Information Center

    Wenk, Manuel; Waurick, Rene; Schotes, David; Wenk, Melanie; Gerdes, Christina; Van Aken, Hugo K.; Popping, Daniel M.

    2009-01-01

    Simulation-based teaching (SBT) is increasingly used in medical education. As an alternative to other teaching methods there is a lack of evidence concerning its efficacy. The aim of this study was to evaluate the potency of SBT in anesthesia in comparison to problem-based discussion (PBD) with students in a randomized controlled setting.…

  15. Simulating the Camp David Negotiations: A Problem-Solving Tool in Critical Pedagogy

    ERIC Educational Resources Information Center

    McMahon, Sean F.; Miller, Chris

    2013-01-01

    This article reflects critically on simulations. Building on the authors' experience simulating the Palestinian-Israeli-American Camp David negotiations of 2000, they argue that simulations are useful pedagogical tools that encourage creative--but not critical--thinking and constructivist learning. However, they can also have the deleterious…

  16. Diagnosing problems with imputation models using the Kolmogorov-Smirnov test: a simulation study

    PubMed Central

    2013-01-01

    Background Multiple imputation (MI) is becoming increasingly popular as a strategy for handling missing data, but there is a scarcity of tools for checking the adequacy of imputation models. The Kolmogorov-Smirnov (KS) test has been identified as a potential diagnostic method for assessing whether the distribution of imputed data deviates substantially from that of the observed data. The aim of this study was to evaluate the performance of the KS test as an imputation diagnostic. Methods Using simulation, we examined whether the KS test could reliably identify departures from assumptions made in the imputation model. To do this we examined how the p-values from the KS test behaved when skewed and heavy-tailed data were imputed using a normal imputation model. We varied the amount of missing data, the missing data models and the amount of skewness, and evaluated the performance of KS test in diagnosing issues with the imputation models under these different scenarios. Results The KS test was able to flag differences between the observations and imputed values; however, these differences did not always correspond to problems with MI inference for the regression parameter of interest. When there was a strong missing at random dependency, the KS p-values were very small, regardless of whether or not the MI estimates were biased; so that the KS test was not able to discriminate between imputed variables that required further investigation, and those that did not. The p-values were also sensitive to sample size and the proportion of missing data, adding to the challenge of interpreting the results from the KS test. Conclusions Given our study results, it is difficult to establish guidelines or recommendations for using the KS test as a diagnostic tool for MI. The investigation of other imputation diagnostics and their incorporation into statistical software are important areas for future research. PMID:24252653

  17. Enhanced genetic algorithm optimization model for a single reservoir operation based on hydropower generation: case study of Mosul reservoir, northern Iraq.

    PubMed

    Al-Aqeeli, Yousif H; Lee, T S; Abd Aziz, S

    2016-01-01

    Achievement of the optimal hydropower generation from operation of water reservoirs, is a complex problems. The purpose of this study was to formulate and improve an approach of a genetic algorithm optimization model (GAOM) in order to increase the maximization of annual hydropower generation for a single reservoir. For this purpose, two simulation algorithms were drafted and applied independently in that GAOM during 20 scenarios (years) for operation of Mosul reservoir, northern Iraq. The first algorithm was based on the traditional simulation of reservoir operation, whilst the second algorithm (Salg) enhanced the GAOM by changing the population values of GA through a new simulation process of reservoir operation. The performances of these two algorithms were evaluated through the comparison of their optimal values of annual hydropower generation during the 20 scenarios of operating. The GAOM achieved an increase in hydropower generation in 17 scenarios using these two algorithms, with the Salg being superior in all scenarios. All of these were done prior adding the evaporation (Ev) and precipitation (Pr) to the water balance equation. Next, the GAOM using the Salg was applied by taking into consideration the volumes of these two parameters. In this case, the optimal values obtained from the GAOM were compared, firstly with their counterpart that found using the same algorithm without taking into consideration of Ev and Pr, secondly with the observed values. The first comparison showed that the optimal values obtained in this case decreased in all scenarios, whilst maintaining the good results compared with the observed in the second comparison. The results proved the effectiveness of the Salg in increasing the hydropower generation through the enhanced approach of the GAOM. In addition, the results indicated to the importance of taking into account the Ev and Pr in the modelling of reservoirs operation.

  18. Multi-Physics Modelling of Fault Mechanics Using REDBACK: A Parallel Open-Source Simulator for Tightly Coupled Problems

    NASA Astrophysics Data System (ADS)

    Poulet, Thomas; Paesold, Martin; Veveakis, Manolis

    2017-03-01

    Faults play a major role in many economically and environmentally important geological systems, ranging from impermeable seals in petroleum reservoirs to fluid pathways in ore-forming hydrothermal systems. Their behavior is therefore widely studied and fault mechanics is particularly focused on the mechanisms explaining their transient evolution. Single faults can change in time from seals to open channels as they become seismically active and various models have recently been presented to explain the driving forces responsible for such transitions. A model of particular interest is the multi-physics oscillator of Alevizos et al. (J Geophys Res Solid Earth 119(6), 4558-4582, 2014) which extends the traditional rate and state friction approach to rate and temperature-dependent ductile rocks, and has been successfully applied to explain spatial features of exposed thrusts as well as temporal evolutions of current subduction zones. In this contribution we implement that model in REDBACK, a parallel open-source multi-physics simulator developed to solve such geological instabilities in three dimensions. The resolution of the underlying system of equations in a tightly coupled manner allows REDBACK to capture appropriately the various theoretical regimes of the system, including the periodic and non-periodic instabilities. REDBACK can then be used to simulate the drastic permeability evolution in time of such systems, where nominally impermeable faults can sporadically become fluid pathways, with permeability increases of several orders of magnitude.

  19. Naturally fractured reservoirs: Optimized E and P strategies using a reaction-transport-mechanical simulator in an integrated approach. Annual report, 1996--1997

    SciTech Connect

    Hoak, T.; Jenkins, R.; Ortoleva, P.; Ozkan, G.; Shebl, M.; Sibo, W.; Tuncay, K.; Sundberg, K.

    1998-07-01

    The methodology and results of this project are being tested using the Andector-Goldsmith Field in the Permian Basin, West Texas. The study area includes the Central Basin Platform and the Midland Basin. The Andector-Goldsmith Field lies at the juncture of these two zones in the greater West Texas Permian Basin. Although the modeling is being conducted in this area, the results have widespread applicability to other fractured carbonate and other reservoirs throughout the world.

  20. Improved Simulation of Subsurface Flow in Heterogeneous Reservoirs Using a Fully Discontinuous Control-Volume-Finite-Element Method, Implicit Timestepping and Dynamic Unstructured Mesh Optimization

    NASA Astrophysics Data System (ADS)

    Salinas, P.; Jackson, M.; Pavlidis, D.; Pain, C.; Adam, A.; Xie, Z.; Percival, J. R.

    2015-12-01

    We present a new, high-order, control-volume-finite-element (CVFE) method with discontinuous representation for pressure and velocity to simulate multiphase flow in heterogeneous porous media. Time is discretized using an adaptive, fully implicit method. Heterogeneous geologic features are represented as volumes bounded by surfaces. Within these volumes, termed geologic domains, the material properties are constant. A given model typically contains numerous such geologic domains. Our approach conserves mass and does not require the use of CVs that span domain boundaries. Computational efficiency is increased by use of dynamic mesh optimization, in which an unstructured mesh adapts in space and time to key solution fields, such as pressure, velocity or saturation, whilst preserving the geometry of the geologic domains. Up-, cross- or down-scaling of material properties during mesh optimization is not required, as the properties are uniform within each geologic domain. We demonstrate that the approach, amongst other features, accurately preserves sharp saturation changes associated with high aspect ratio geologic domains such as fractures and mudstones, allowing efficient simulation of flow in highly heterogeneous models. Moreover, accurate solutions are obtained at significantly lower computational cost than an equivalent fine, fixed mesh and conventional CVFE methods. The use of implicit time integration allows the method to efficiently converge using highly anisotropic meshes without having to reduce the time-step. The work is significant for two key reasons. First, it resolves a long-standing problem associated with the use of classical CVFE methods to model flow in highly heterogeneous porous media, in which CVs span boundaries between domains of contrasting material properties. Second, it reduces computational cost/increases solution accuracy through the use of dynamic mesh optimization and time-stepping with large Courant number.

  1. Mathematical modeling of the thermal and hydrodynamic structure of the cooling reservoir

    NASA Astrophysics Data System (ADS)

    Saminskiy, G.; Debolskaya, E.

    2012-04-01

    Hydrothermal conditions of the cooling reservoir is determined by the heat and mass transfer from the water surface to the atmosphere and the processes of heat transfer directly in the water mass of the reservoir. As the capacity of power plants, the corresponding increase in the volume of heated water and the use of deep lakes and reservoirs as coolers there is a need to develop new, more accurate, and the application of existing methods for the numerical simulation. In calculating the hydrothermal regime it must take into account the effect of wind, density (buoyancy) forces, and other data of the cooling reservoir. In addition to solving practical problems it is important to know not only the magnitude of the average temperature, but also its area and depth distribution. A successful solution can be achieved through mathematical modeling of general systems of equations of transport processes and the correct formulation of the problem, based on appropriate initial data. The purpose of the work is application of software package GETM for simulating the hydrothermal regime of cooling reservoir with an estimate of three-dimensional structure of transfer processes, the effects of wind, the friction of the water surface. Three-dimensional models are rarely applied, especially for far-field problems. If such models are required, experts in the field must develop and apply them. Primary physical processes included are surface heat transfer, short-wave and long-wave radiation and penetration, convective mixing, wind and flow induced mixing, entrainment of ambient water by pumped-storage inflows, inflow density stratification as impacted by temperature and dissolved and suspended solids. The model forcing data consists of the system bathymetry developed into the model grid; the boundary condition flow and temperature; the tributary and flow and temperature; and the system meteorology. Ivankovskoe reservoir belongs to the reservoirs of valley type (Tver region, Russia). It

  2. INCREASING HEAVY OIL RESERVES IN THE WILMINGTON OIL FIELD THROUGH ADVANCED RESERVOIR CHARACTERIZATION AND THERMAL PRODUCTION TECHNOLOGIES

    SciTech Connect

    Unknown

    2001-08-08

    The objective of this project is to increase the recoverable heavy oil reserves within sections of the Wilmington Oil Field, near Long Beach, California, through the testing and application of advanced reservoir characterization and thermal production technologies. The hope is that successful application of these technologies will result in their implementation throughout the Wilmington Field and, through technology transfer, will be extended to increase the recoverable oil reserves in other slope and basin clastic (SBC) reservoirs. The existing steamflood in the Tar zone of Fault Block II-A (Tar II-A) has been relatively inefficient because of several producibility problems which are common in SBC reservoirs: inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil and non-uniform distribution of the remaining oil. This has resulted in poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. A suite of advanced reservoir characterization and thermal production technologies are being applied during the project to improve oil recovery and reduce operating costs, including: (1) Development of three-dimensional (3-D) deterministic and stochastic reservoir simulation models--thermal or otherwise--to aid in reservoir management of the steamflood and post-steamflood phases and subsequent development work. (2) Development of computerized 3-D visualizations of the geologic and reservoir simulation models to aid reservoir surveillance and operations. (3) Perform detailed studies of the geochemical interactions between the steam and the formation rock and fluids. (4) Testing and proposed application of a

  3. The Use of Simulation Models in Solving the Problems of Merging two Plants of the Company

    NASA Astrophysics Data System (ADS)

    Sedláček, Michal