Development of an Efficient Embedded Discrete Fracture Model for 3D Compositional Reservoir Simulation in Fractured Reservoirs
Development of an Efficient Embedded Discrete Fracture Model for 3D Compositional Reservoir Simulation in Fractured Reservoirs
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DOI：
10.2118/154246-pa
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发表时间：
2014-04-01
期刊：
影响因子：
3.6
通讯作者：
Johns, Russell T.
中科院分区：
文献类型：
--
作者：
Moinfar, Ali;Varavei, Abdoljalil;Johns, Russell T.
世界各地许多天然裂缝性油藏已严重枯竭，为了进一步开发，需要改进石油采收率 (IOR) 工艺。因此，裂缝性油藏的建模最近受到越来越多的关注。由于渗透率各向异性和对比，天然裂缝性储层（NFR）的准确建模和模拟仍然具有挑战性。传统双孔隙度和双渗透率模型固有的非物理抽象使其不足以解决裂缝性油藏中的不同流体流动问题。此外，最新的离散裂缝建模技术可能会受到模拟运行时间过长的影响，并且业界尚未广泛使用此类方法，尽管它们比双连续介质模型能够更准确地表示裂缝储层。我们为内部成分储层模拟器开发了嵌入式离散裂缝模型 (DFM)，该模型借用了传统的双介质概念 双连续介质模型，还明确地结合了每个断裂的影响。该模型与现有的有限差分油藏模拟器兼容。与双连续介质模型相比，裂缝具有任意方向，可以是倾斜的或垂直的，从而体现了典型 NFR 的复杂性。通过将结果与包含正交断裂和非对齐断裂的案例研究的细网格、显式断裂模拟的结果进行比较，证实了嵌入式 DFM 的准确性。我们还进行了网格敏感性研究，以显示该方法在网格细化时的收敛性。我们的模拟表明，为了获得准确的结果，嵌入式离散裂缝模型可能只需要在裂缝周围进行适度的网格细化，因此提供了一种计算有效的方法。此外，还提供了注水、注气和一次耗尽的示例，以证明所开发的模拟 NFR 中流体流动方法的性能和适用性。
Many naturally fractured reservoirs around the world have depleted significantly, and improved-oil-recovery (IOR) processes are necessary for further development. Hence, the modeling of fractured reservoirs has received increased attention recently. Accurate modeling and simulation of naturally fractured reservoirs (NFRs) is still challenging because of permeability anisotropies and contrasts. Nonphysical abstractions inherent in conventional dual-porosity and dual-permeability models make them inadequate for solving different fluid-flow problems in fractured reservoirs. Also, recent technologies for discrete fracture modeling may suffer from large simulation run times, and the industry has not used such approaches widely, even though they give more-accurate representations of fractured reservoirs than dual-continuum models.We developed an embedded discrete fracture model (DFM) for an in-house compositional reservoir simulator that borrows the dual-medium concept from conventional dual-continuum models and also incorporates the effect of each fracture explicitly. The model is compatible with existing finite-difference reservoir simulators. In contrast to dual-continuum models, fractures have arbitrary orientations and can be oblique or vertical, honoring the complexity of a typical NFR. The accuracy of the embedded DFM is confirmed by comparing the results with the fine-grid, explicit-fracture simulations for a case study including orthogonal fractures and a case with a nonaligned fracture. We also perform a grid-sensitivity study to show the convergence of the method as the grid is refined. Our simulations indicate that to achieve accurate results, the embedded discrete fracture model may only require moderate mesh refinement around the fractures and hence offers a computationally efficient approach. Furthermore, examples of waterflooding, gas injection, and primary depletion are presented to demonstrate the performance and applicability of the developed method for simulating fluid flow in NFRs.