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Francisco Marcondes Choongyong Han Kamy Sepehrnoori 《Journal of Petroleum Science and Engineering》2008,63(1-4):53-60
Corner-point meshes have been implemented in several commercial reservoir simulators due to their flexibility to deal with several important features of the hydrocarbon bearing-reservoirs, such as irregular boundaries, geologic fractures, and faults. Although this type of mesh presents an important step in discretization of the domains for reservoirs, some parts of the approximate equation in discretized formulations are neglected in most commercial simulators. The neglected terms are related to the cross derivatives and, in general, are neglected to produce the same Jacobian stencil as when Cartesian grids are employed. This work presents an investigation of the effect of cross derivatives in discretization schemes using structured non-orthogonal boundary-fitted meshes in conjunction with a compositional reservoir simulator. The main goal is to investigate the difference between the numerical results with and without the cross derivatives that arise when the Cartesian equations are written for a transformed plane. We used an in-house compositional reservoir simulator to carry out this study. The component mass balance equations for a compositional, multiphase, multi-component fluid flow are solved using a fully implicit reservoir simulator in conjunction with the finite volume method. The results of several reservoir simulation case studies that were performed to carry out this study are presented in this paper. 相似文献
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Faruk O. Alpak Carlos Torres-Verdín Kamy Sepehrnoori Sheng Fang Leonid Knizhnerman 《Journal of Petroleum Science and Engineering》2003,40(3-4):121-144
We develop and validate a novel numerical algorithm for the simulation of axisymmetric single-phase fluid flow phenomena in porous and permeable media. In this new algorithm, the two-dimensional parabolic partial differential equation for fluid flow is transformed into an explicit finite-difference operator problem. The latter is solved by making use of an extended Krylov subspace method (EKSM) constructed with both positive and inverse powers of the finite-difference operator. A significant advantage of the method of solution presented in this paper is that simulations of pressure can be obtained at a multitude of times with practically the same efficiency as that of a single-time simulation. Moreover, the usage of inverse powers of the finite-difference operator provides a substantial increase in efficiency with respect to that of standard Krylov subspace methods. Tests of numerical performance with respect to analytical solutions for point and line sources validate the accuracy of the developed method of solution. We also validate the algorithm by making comparisons between analytical and numerical solutions in the Laplace transform domain. Additional tests of accuracy and efficiency are performed against a commercial simulator for spatially complex and anisotropic models of permeable media. 相似文献
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Simulation of shale gas transport and production with complex fractures using embedded discrete fracture model 下载免费PDF全文
Wei Yu Yifei Xu Malin Liu Kan Wu Kamy Sepehrnoori 《American Institute of Chemical Engineers》2018,64(6):2251-2264
The goal of this study is to develop a new model to simulate gas and water transport in shale nanopores and complex fractures. A new gas diffusivity equation was first derived to consider multiple important physical mechanisms such as gas desorption, gas slippage and diffusion, and non‐Darcy flow. For complex fractures, a state‐of‐the‐art embedded discrete fracture model (EDFM) was implemented. Numerical model is verified against a commercial reservoir simulator for shale gas simulation with multiple planar fractures. After that, a series of simulation studies was performed to investigate the impacts of complex gas transport mechanisms and various fracture geometries on well performance. The critical parameters controlling well performance are identified. The simulation results reveal that modeling of gas production from complex fractures as well as modeling important gas transport mechanisms in shale gas reservoirs is extremely significant. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2251–2264, 2018 相似文献
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Jing Wang Hui‐Qing Liu Hong‐ling Zhang Kamy Sepehrnoori 《American Institute of Chemical Engineers》2017,63(10):4628-4641
Preformed particle gel (PPG) treatment is a proven cost‐effective method for improving oil recovery. Although PPG system has a suspension‐like property, it has different propagation rules from the rigid particle suspension in porous media because of its good deformation property. In this study, an advanced phenomenological model of PPG propagation in porous media is presented. The model includes both PPG plugging and restarting behaviors. Log‐normal and normal distribution functions have been introduced in this model to calculate the PPG plugging probability. Power‐law equation is used to calculate the PPG restarting rate. This method can represent the commensurate relation between PPG and throat size. Then, the equations are solved numerically, using an explicit finite‐difference formulation in conjunction with a fourth‐order Runge‐Kutta method. The results match favorably with several laboratory experiments. Finally, the propagation rules and sensitivity analysis of PPG size, permeability and injection rate to propagation rules, and permeability reduction are performed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4628–4641, 2017 相似文献
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超临界CO2压裂技术现状与展望 总被引:5,自引:3,他引:2
以水基压裂液开发非常规油气过程中所面临的问题为背景,总结了超临界CO2压裂技术的独特优势、技术特点、工艺流程及其作业机制。全面分析了超临界CO2压裂技术的起源、超临界CO2压裂岩石起裂机制、缝内携砂规律、井筒流动与控制、压裂设备及现场试验等研究发展现状,得到了当前阻碍该技术工业化应用的关键问题,并给出了相应对策。针对超临界CO2压裂岩石起裂机制的研究多为现象性描述,未来应重视理论分析与模拟实验相结合,给出定量评价方法;超临界CO2缝内携砂能力的研究除了加强增黏剂方向的攻关力度外,研发纳米纤维实现物理增黏、开发新型低密度支撑剂、提高施工设备技术参数等也是有益的工作。未来超临界CO2压裂技术将逐渐由直井单层压裂向水平井多级压裂发展并与连续油管拖动压裂相结合,逐渐满足页岩气、煤层气、致密砂岩气等非常规油气的规模化开发需求。 相似文献
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Wettability alteration mechanism is still believed to be the main contributor to low salinity water injection (LSWI) effect on oil recovery from carbonate rocks. The authors investigated the main mechanism and contributor to the LSWI effect on oil recovery from carbonate rocks through history matching recently published corefloods using the UTCHEM simulator. The history match results suggest that wettability alteration has negligible effect on water relative permeability, which could be related to the double electric layer expansion mechanism. This paper provides a basis to develop a LSWI model to predict oil recovery from carbonate rocks. 相似文献
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以水基压裂液开发非常规油气过程中所面临的问题为背景,总结了超临界CO2压裂技术的独特优势、技术特点、工艺流程及其作业机制。全面分析了超临界CO2压裂技术的起源、超临界CO2压裂岩石起裂机制、缝内携砂规律、井筒流动与控制、压裂设备及现场试验等研究发展现状,得到了当前阻碍该技术工业化应用的关键问题,并给出了相应对策。针对超临界CO2压裂岩石起裂机制的研究多为现象性描述,未来应重视理论分析与模拟实验相结合,给出定量评价方法;超临界CO2缝内携砂能力的研究除了加强增黏剂方向的攻关力度外,研发纳米纤维实现物理增黏、开发新型低密度支撑剂、提高施工设备技术参数等也是有益的工作。未来超临界CO2压裂技术将逐渐由直井单层压裂向水平井多级压裂发展并与连续油管拖动压裂相结合,逐渐满足页岩气、煤层气、致密砂岩气等非常规油气的规模化开发需求。 相似文献
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As a result of advances in horizontal completions
and multi-stage hydraulic fracturing, the U.S. has
been able to economically develop several decades of
worth of natural gas. However, a considerable concern has
risen on the economic viability of shale gas development
for reasons associated with the fast production declines as
well as recent down-turns of natural gas prices besides rises
in the costs of new technologies. Therefore, an economic
analysis is required to investigate the profitability of the refracturing
treatment of unconventional gas resources. Net
present value of cash flows and internal rate of return are
calculated for a range of gas prices considering 20 years of
natural gas production from a typical unconventional shale
gas reservoir. A systematic comparison is then accomplished
for three scenarios: (1) re-fracturing versus no refracturing,
(2) combination of re-fracturing and drilling
new wells, and (3) time-dependent re-fracturing treatment.
Further, this paper incorporates the cost of re-fracturing
treatment, the cost of drilling a new horizontal well, the
water treatment cost, as well as the current and future price
of natural gas in the model. The findings of this work
would help the future re-stimulation development plans of
the emerging unconventional shale gas plays. 相似文献
10.
Abstract The data assimilation process of adjusting variables in a reservoir simulation model to honor observations of field data is known as history matching and has been extensively studied for a few decades. However, limited success has been achieved due to the high complexity of the problem and the large computational effort required in the real fields. Successful applications of the ensemble Kalman filter (EnKF) to reservoir history matching have been reported in various publications. The EnKF is a sequential method: once new data are available, only these data are used to update all the unknown reservoir properties while previous geological information is unused directly. In this method, multiple reservoir models rather than one single model are implemented, and each model is called a member. Conventionally, the impact of each member on the updating is equally treated. Another approach is the weighted EnKF. During the updating, the method weighs the contribution of each member through the comparison between the simulation response and the measurements. Better matching performance has been found in the weighted EnKF than in the conventional EnKF. To improve computational efficiency, two-level high-performance computing for reservoir history matching process is implemented in this research, distributing ensemble members simultaneously while simulating each member in a parallel style. An automatic history-matching module based on the weighted EnKF and high-performance computing is developed and validated through a synthetic case operating from primary, waterflooding to flooding of water alternating with gas. The study shows that the weighted EnKF improves the matching results, and the high-performance computing process significantly reduces the history matching execution time. 相似文献