论文标题

耦合流和地球力学的嵌入式断裂模型

Embedded Fracture Model for Coupled Flow and Geomechanics

论文作者

Shovkun, I., Garipov, T., Tchelepi, H. A.

论文摘要

流体注入和生产会导致储层压力变化,从而导致地下变形。这种现象在具有丰富断裂和断层的储层中尤为重要,因为诱导的滑动和裂缝的打开可能会显着改变其液压特性。在自然断裂的储层中对强烈耦合的孔刺过程进行建模是一个具有挑战性的问题。离散断裂模型(DFM)是一种对断裂储层中的耦合流量和力学进行建模的最新方法。此方法需要构造与断裂构成的计算网格,这在复杂的3D设置中非常具有挑战性。这项研究的目的是开发一种数值方法,该方法不需要骨折附近的网格,并且可以有效地模拟断裂的储层中的水力力学相互作用。我们利用基于强大的不连续性方法(SDA)的制剂,用于机械和嵌入式离散裂缝模型(EDFM)。我们首先提出数学表述,并强调断裂滑动和开口的运动学方面。然后,我们引入了一系列的机械测试,这些测试研究了模型的空间收敛,并将其精度与离散断裂模型(DFM)进行了比较。我们最终考虑了储层的合成耦合案例,并比较了SDA和DFM方法的性能。我们的结果表明所提出的SDA算法的超线性空间收敛。数值模拟证实了所提出的方法在地下应用中对耦合效应进行建模的适用性。

Fluid injection and production cause changes in reservoir pressure, which result in deformations in the subsurface. This phenomenon is particularly important in reservoirs with abundant fractures and faults because the induced slip and opening of the fractures may significantly alter their hydraulic properties. Modeling strongly coupled poro-mechanical processes in naturally fractured reservoirs is a challenging problem. The Discrete Fracture Model (DFM) is a state-of-art method for modeling coupled flow and mechanics in fractured reservoirs. This method requires constructing computational grids that comform to fractures, which is very challenging in complex 3D settings. The objective of this study is to develop a numerical method that does not require gridding near fractures and can efficiently model hydromechanical interactions in fractured reservoirs. We utilize formulations based on the Strong Discontinuity Approach (SDA) for mechanics and Embedded Discrete Fracture Model (EDFM) for flow. We first present a mathematical formulation and emphasize the kinematic aspects of fracture slip and opening. We then introduce a series of mechanical tests that investigate the spatial convergence of the model and compare its accuracy with the Discrete Fracture Model (DFM). We finally consider a synthetic coupled case of a reservoir with several fractures and compare the performance of the SDA and DFM methods. Our results indicate super-linear spatial convergence of the proposed SDA algorithm. Numerical simulations confirm the applicability of the proposed method to modeling the coupling effects in subsurface applications.

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