Extended finite element simulation of fracture network propagation in formation containing frictional and cemented natural fractures
Extended finite element simulation of fracture network propagation in formation containing frictional and cemented natural fractures
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含有摩擦和胶结天然裂缝的地层中裂缝网络扩展的扩展有限元模拟
DOI：
10.1016/j.jngse.2017.12.013
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发表时间：
2018-02
影响因子：
--
通讯作者：
Wu HengAn
中科院分区：
文献类型：
--
作者：
Wang XiaoLong;Shi Fang;Liu Chuang;Lu DeTang;Liu He;Wu HengAn
页岩气储层通常需要水力压裂处理来产生复杂的裂缝网络以提高产量。页岩地层中通常含有胶结和胶结的天然裂缝。水力裂缝与这两种类型的预先存在的天然裂缝之间的相互作用是不同的。本文采用扩展有限元法（XFEM）建立了二维流固耦合水力压裂模型，模拟水力压裂裂缝与天然裂缝的相互作用，进而模拟裂缝网络的形成。结果表明，当水力裂缝与天然裂缝相交时，水力裂缝可能被阻滞，沿天然裂缝沿着方向扩展，也可能不受影响地穿过天然裂缝。对于摩擦型天然裂隙，裂隙网络的形成受裂隙夹角、摩擦系数、应力各向异性和岩石抗拉强度等因素的影响。研究发现，减小应力差和界面摩擦力，或提高岩石抗拉强度，都可能导致更复杂的裂隙网络。对于胶结型天然裂缝，裂缝网络的形成主要取决于裂缝与岩石的夹角以及岩石与水泥的韧性比。天然裂缝的交角和胶结韧性越小，岩石断裂韧性越大，裂缝网络越复杂。此外，对于相同的天然裂缝初始几何构型，水力压裂往往导致含摩擦性天然裂缝地层的裂缝网络比含胶结性天然裂缝地层的复杂。这些发现为裂缝复杂性的性质和程度提供了新的见解，有助于优化页岩气藏的水力压裂设计。
Shale gas reservoirs often need hydraulic fracturing treatments to create complex fracture network to enhance production. Frictional and cemented natural fractures are often contained in shale formations. The interactions between the hydraulic fractures and these two types of pre-existing natural fractures are different. In this study, we established a two-dimensional fluid-solid coupled hydraulic fracturing model using the extended finite element method (XFEM) to simulate the interactions between hydraulic fractures and natural fractures, and further the formation of fracture network. The results show that when a hydraulic fracture intersects with a natural fracture, the hydraulic fracture may be arrested and propagate along the direction of natural fracture, or cross the natural fracture without being affected. For the frictional natural fractures, the intersection angle, frictional coefficient, stress anisotropy and rock tensile strength have a significant influence on creating fracture network. It is found that decreasing stress difference and interfacial friction, or increasing rock tensile strength may lead to more complex fracture network. For the cemented natural fractures, the intersection angle and the ratio of cement toughness and rock toughness play critical roles in the creation of fracture network. Smaller intersection angle and cement toughness of natural fractures and larger rock fracture toughness often lead to more complex fracture network. In addition, for the same initial geometrical configuration of natural fractures, hydraulic fracturing often leads to more complex fracture network in formations containing frictional natural fractures compared with formations containing cemented natural fractures. These findings offer new insights into the nature and degree of fracture complexity, helping to optimize hydraulic fracturing design in shale gas reservoirs.
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影响因子：
6.1
作者：
A. A. Daneshy-A.
通讯作者：
A. A. Daneshy-A.
DOI：
10.2118/94568-ms
发表时间：
2005
期刊：
--
影响因子：
--
作者：
N. Potluri;D. Zhu;A. Hill
通讯作者：
N. Potluri;D. Zhu;A. Hill
DOI：
--
发表时间：
2015-11
期刊：
--
影响因子：
--
作者：
R. Jeffrey;James Kear;D. Kasperczyk;Xi Zhang;D. Chuprakov;Romain Prioul;J. Schouten
通讯作者：
R. Jeffrey;James Kear;D. Kasperczyk;Xi Zhang;D. Chuprakov;Romain Prioul;J. Schouten
DOI：
10.1016/0148-9062(96)83899-x
发表时间：
--
期刊：
--
影响因子：
--
作者：
E. C.
通讯作者：
E. C.
影响因子：
2.9
作者：
E. Budyn;G. Zi;N. Moës;T. Belytschko
通讯作者：
E. Budyn;G. Zi;N. Moës;T. Belytschko