Effects of elastic anisotropy on primary petroleum migration through buoyancy-driven crack propagation
Effects of elastic anisotropy on primary petroleum migration through buoyancy-driven crack propagation
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DOI：
10.1007/s40948-017-0062-6
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发表时间：
2017-05
影响因子：
5
通讯作者：
Z.-H. Jin;S. E. Johnson
中科院分区：
文献类型：
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作者：
Z.-H. Jin;S. E. Johnson
物质的各向异性对沉积盆地和其他具有层状或叶理岩石的环境中的流体输运行为有重要影响。在本文中，我们提出了一个断裂力学模型，调查石油（石油和天然气）通过传播的垂直，浮力驱动的刀片裂纹在横向各向同性源岩的初次迁移。假定烃源岩具有非常低的渗透率，因此可以模拟为线弹性介质。断裂参数（应力强度因子和裂纹张开位移）推导出使用等效的各向异性弹性性能。裂纹扩展速度（即，石油运移速度）和裂缝开口（裂缝孔径）使用断裂力学准则以及流体力学的平面Poiffille流动方程的一阶近似来确定。对于近水平分层，当垂直方向的弹性模量小于水平方向的弹性模量时，流体运移速度和裂缝开度显著增大。最后，我们讨论了公式的适用性，各向同性材料沿着与等效各向异性弹性参数，本文介绍了裂纹的各向异性岩石的裂缝开口。
Material anisotropy may significantly influence the behavior of fluid transport in sedimentary basins and other environments with laminated or foliated rocks. In this paper, we present a fracture mechanics model to investigate primary migration of petroleum (oil and gas) through propagation of a vertical, buoyancy-driven blade crack in a transversely isotropic source rock. The source rock is assumed to have very low permeability and hence can be modeled as a linear elastic medium. Fracture parameters (stress intensity factor and crack opening displacement) are derived using an equivalent set of anisotropic elastic properties. The crack propagation velocity (i.e., petroleum migration velocity) and crack opening (fracture aperture) are determined using a fracture mechanics criterion together with the first order approximation of plane Poiseuille flow equations of fluid mechanics. For subhorizontal layering, we find that the fluid migration velocity and fracture aperture are significantly increased if the elastic modulus in the vertical direction is smaller than that in the horizontal direction. Finally, we discuss the applicability of the formula for isotropic materials along with the equivalent anisotropic elastic parameters introduced in this paper to evaluate fracture aperture for cracks in anisotropic rocks.