基于EDFM的致密油藏分段压裂水平井数值模拟

EDFM-based Numerical Simulation of Horizontal Wells with Multi-stage Hydraulic Fracturing in Tight Reservoirs

张烈辉 刘沙 雍锐 李博 赵玉龙

ZHANGLiehui LIUSha YONGRui LIBo ZHAOYulong

“油气藏地质及开发工程”国家重点实验室·西南石油大学, 四川 成都 610500 中国石油西南油气田分公司页岩气研究院, 四川 成都 610051 广州海洋地质调查局, 广东 广州 510075

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China Institute of Shale Gas, Southwest Oil & Gas Field Company, PetroChina, Chengdu, Sichuan 610051, China Guangzhou Marine Geological Survey, Guangzhou, Guangdong 510075, China

为了解决致密油藏分段压裂水平井由于裂缝模型建立难度大导致的产量评价困难的问题，通过引入嵌入式离散裂缝模型（Embedded Discrete Fracture Model，EDFM），采用矩形网格，建立了考虑重力和应力敏感效应的三维致密油藏分段压裂水平井模型。首先，用Saphir对该模型的准确性进行了检验；然后，利用该模型进行了三维致密油藏、天然裂缝性致密油藏以及裂缝分布形态影响的数值模拟研究。结果表明，嵌入式离散裂缝模型能较好反映流体在天然裂缝和压裂缝网内的流动特征；压裂施工位置应选择天然裂缝发育的区域；分段压裂水平井的裂缝分布形态对产能影响显著，缝网与基质接触面积越大，油井产能越大，因此，最优化的裂缝分布可作为体积压裂施工目标。

Fracture modeling for horizontal wells with multi-stage hydraulic fracturing (fracking) in tight reservoirs is extremely challenging, which means that evaluating the productivity of these wells is difficult. To address this problem, a threedimensional (3D) model of horizontal wells with multi-stage hydraulic fracturing in tight reservoirs, which accounts for the effects of gravity and stress sensitivity, was constructed using the embedded discrete fracture model (EDFM) with a rectangular grid. First, Saphir was used to examine the accuracy of this model. The numerical simulation of 3D tight reservoirs, tight naturally fractured reservoirs, and the effects of fracture distribution and morphology was then performed using this model. It was shown that EDFM produces an accurate depiction of fluid flow characteristics in both natural fractures and fracking-induced fracture networks. It was concluded that fracking should be performed in areas where natural fractures are well-developed. Moreover, it was found that well productivity is significantly affected by the distribution and morphology of fractures in a horizontal well with multi-stage fracking, where the greater the area of contact between the fracture network and matrix, the greater the well productivity. Therefore, one of the goals of massive hydraulic fracturing is to realize optimal fracture distribution.

10.11885/j.issn.1674-5086.2018.11.21.05