Fracture-Cross-Flow Equilibrium in Compositional Two-Phase Reservoir Simulation
Fracture-Cross-Flow Equilibrium in Compositional Two-Phase Reservoir Simulation
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DOI：
10.2118/184402-pa
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发表时间：
2017-06
期刊：
影响因子：
3.6
通讯作者：
A. Zidane;A. Firoozabadi
中科院分区：
文献类型：
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作者：
A. Zidane;A. Firoozabadi
摘要裂缝介质中的成分两相流具有广泛的应用，包括在地下注入二氧化碳（CO 2）以提高石油采收率和封存CO 2。在最近的一项工作中，我们使用单相可压缩湍流的交叉湍流平衡（FCFE）方法来模拟裂缝性油藏。在这项工作中，我们应用相同的概念，在组成的两相湍流，并表明，我们可以计算的所有细节的两相湍流在裂缝介质与中央处理器（CPU）的时间可比的均匀介质。如此高的计算效率取决于FCFE的概念，以及裂缝中输运方程的隐式解，以避免小裂缝单元中的Courant-Freidricks-Levy（CFL）条件。裂缝中两相组分渗流的隐式解存在一些单相渗流中不存在的问题。当多个裂缝在一个界面处相交时，复杂性产生于相a中组分i的摩尔浓度的导数相对于总摩尔浓度的向上流动。此外，由于重力的作用，可能会产生逆流，这增加了使用FCFE概念时的复杂性。我们通过在裂缝/裂缝界面和基质/裂缝界面处提供上游技术来克服这些复杂性。我们计算各种衍生物在恒定的体积V和温度T，通过在断裂单元和矩阵域中执行Crackash计算，以捕获在基体/断裂界面处的不连续性。我们在各种例子中证明了所提出的算法在八组分混合物中不同复杂程度的问题中的效率和准确性。在具有4，300个单元（1，100个裂缝单元）的一个示例中，到1次孔隙体积注入（PVI）的CPU时间大约为3小时。如果没有骨折，CPU时间为2小时28分钟。
Summary Compositional two-phase flow in fractured media has wide applications, including carbon dioxide (CO 2 ) injection in the subsurface for improved oil recovery and for CO 2 sequestration. In a recent work, we used the fracture-crossflow-equilibrium (FCFE) approach in single-phase compressible flow to simulate fractured reservoirs. In this work, we apply the same concept in compositional two-phase flow and show that we can compute all details of two-phase flow in fractured media with a central-processing-unit (CPU) time comparable with that of homogeneous media. Such a high computational efficiency is dependent on the concept of FCFE, and the implicit solution of the transport equations in the fractures to avoid the Courant-Freidricks-Levy (CFL) condition in the small fracture elements. The implicit solution of two-phase compositional flow in fractures has some challenges that do not appear in single-phase flow. The complexities arise from the upstreaming of the derivatives of the molar concentration of component i in phase a ð c a ; i Þ with respect to the total molar concentration ð c i Þ when several fractures intersect at one interface. In addition, because of gravity, countercurrent flow may develop, which adds complexity when using the FCFE concept. We overcome these complexities by providing an upstreaming technique at the fracture/fracture interface and the matrix/fracture interface. We calculate various derivatives at constant volume V and temperature T by performing flash calculations in the fracture elements and the matrix domain to capture the discontinuity at the matrix/fracture interface. We demonstrate in various examples the efficiency and accuracy of the proposed algorithm in problems of various degrees of complexity in eight-component mixtures. In one example with 4,300 elements (1,100 fracture elements), the CPU time to 1 pore volume injection (PVI) is approximately 3 hours. Without the fractures, the CPU time is 2 hours and 28 minutes.