| 储层非均质性对水力压裂的影响 |
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| 引用本文： | 王宇,李晓,李守定,郑博,李关访,吴雨松,赵志恒,张搏.储层非均质性对水力压裂的影响[J].工程地质学报(英文版),2015,23(3):511-520. |
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| 作者姓名： | 王宇 李晓 李守定 郑博 李关访 吴雨松 赵志恒 张搏 |
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| 作者单位： | 1.中国科学院地质与地球物理研究所, 中国科学院页岩与地质工程重点实验室 北京 100029; |
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| 基金项目： | 国家自然科学基金项目，中国科学院战略性先导科技专项 B 类(Grants Nos．XDB10030000， XDB10030300)资助． |
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| 摘 要： | 从岩石细观非均质性的特点出发,采用RFPA2D-Flow软件对单孔和双孔数值模型进行压裂计算,研究岩石非均质性对水力压裂的响应,重点探讨双孔模型孔间吸引效应对裂纹演化形态的影响。岩石细观单元的力学、水力学特性由统计分布生成以体现岩石的随机不均质性,水力压裂过程中流体压力传递通过单元渗流-损伤耦合迭代来实现。数值计算结果表明:(1)岩石非均质性影响裂缝的扩展形态,导致水力裂纹尖端微裂纹的分支。随着均质度的增加,水力裂纹的扩展形态变得更加平直光滑,单孔模型两侧裂纹更加对称,双孔间裂纹的连通性变差。(2)岩石的非均匀性对于岩石的起裂压力和地层破裂压力影响较大。随着均质度的增大,起裂应力和地层破裂应力增大,并且两者间的差值逐渐变小,在储层为均质的条件下,两者几乎相等。(3)相同的边界条件下,均质模型的应力分布曲线光滑连续,非均质模型的应力分布曲线呈现出明显波动,井眼对称剖面上的应力分布不尽相同,反映了细观单元强度非均匀性及裂缝扩展形态对应力分布的影响。(4)双孔模型孔间存在孔隙水压力增加带,孔间产生吸引效应,双孔方位影响临界压力。研究结果对水压裂试验设计和现场压裂施工具有一定的参考意义。
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| 关 键 词： | 水力压裂 非均质性 水力裂纹 数值模拟 裂纹演化 |
| 收稿时间： | 2014-05-24 |
INFLUENCE OF RESERVOIR HETEROGENEITY ON HYDROFRACTURE |
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| WANG Yu,LI Xiao,Li Shouding,Zheng Bo,Li Guanfang,Wu Yusong,Zhao Zhiheng,Zhang Bo.INFLUENCE OF RESERVOIR HETEROGENEITY ON HYDROFRACTURE[J].Journal of Engineering Geology,2015,23(3):511-520. |
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| Authors: | WANG Yu LI Xiao Li Shouding Zheng Bo Li Guanfang Wu Yusong Zhao Zhiheng Zhang Bo |
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| Institution: | 1.Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029;2.University of Chinese Academy of Sciences, Beijing 100049 |
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| Abstract: | Based on the mesoscopic heterogeneity of rock, the RFPA2D-Flow software is used to explore the law of fracking. In this model, material is discretized into a large number of elements with the same size and different mechanical and permeable parameters in order to represent heterogeneity of rock. A coupling analysis of seepage and damage under hydraulic fracturing on rock is performed to simulate the fracture process of rock. Through the numerical results of single and double hole model, we draw the conclusions as follows:(1)The rock heterogeneity influences the pattern of fracture, results in the branching of hydraulic fracture. With the increase of the homogeneity, form of hydraulic fracture gets much smoother. The fractures in the single wellbore model are more symmetrical on both sides of wellbore. The connectivity between the double holes gets worse.(2)Heterogeneity of rock has a significant influence on the initiation and breakdown pressure. Both fracture initiation and breakdown pressure values increase with the increasing homogeneity. When the rock is homogeneous, both are almost equal.(3) At the same boundary conditions, the stress distribution curve of homogenous model is smooth and continuous, however, the curve display fluctuation in heterogeneous model. The fluctuation gets obvious with the increasing heterogeneity.(4)Pore pressure increment zone exists between the two holes in the double hole model, anattract effect occurs between the two holes, the critical pressure is influenced by the orientation of the two holes. The above results are of some significance to hydraulic fracturing tests and engineering practice. |
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| Keywords: | Hydraulic fracturing Heterogeneity Hydraulic fracture Numerical simulation Fracture evolution |
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