水平井定向射孔裂缝起裂与穿层特征数值分析

doi:10.11743/ogg20150320

摘要/Abstract

摘要： 为了探索水力裂缝的起裂形式和受控因素影响以及水力裂缝扩展至产层隔层界面处的穿层特征，运用基于有限元的数值模拟方法建立数值模型对其进行分析和研究，重点探讨了压裂双裂缝形成的可能性和条件，模拟了裂缝延伸至产层与隔层界面处的穿层现象。结果表明，地应力差和射孔方位角对压裂裂缝的起裂形式影响显著，地应力差越大，则裂缝从射孔方向起裂的可能性越小，方位角越大，从射孔方向起裂的可能性也越小，此时若水泥环失效，裂缝可从井壁大主应力方向起裂;若满足岩层物理力学与压裂条件，裂缝同时从射孔方向和井壁大主应力方向起裂的双裂缝起裂形式是可能的;在裂缝延伸过程中，产层与隔层弱胶结界面可使裂缝钝化或滑移成“T”型裂缝，弹性模量较小的隔层有利于裂缝穿层并继续延伸。数值分析结果可对水平井射孔参数优化及水力压裂施工提供些许参考。

关键词: 射孔, 双裂缝, 界面, 数值模拟, 水力压裂, 水平井

Abstract: In order to reveal the initiation mode and controlling factors of hydraulic fracture as well as its propagation characteristics near the interface between production layer and barrier, a FEM-based code is employed and several numerical models are built to emphatically discuss the possibility and necessary conditions of the formation of double fractures.The penetration phenomenon of hydraulic fracture near the interface between production layer and barrier is also numerically simulated.Numerical results show that the differential stress and perforation azimuth play an important role in the initiation mode of hydraulic fractures.Either a higher differential stress or a higher azimuth can decrease the possibility of fracture initiation and propagation along the perforation direction.If the cement sheath is failed, a fracture near the well may initiate along the orientation of maximum principal stress.If both mechanical and hydraulic conditions are satisfied, a double fracturing mode, i.e.two fractures initiating synchronously along the orientation of perforation and maximum principal stress, could be obtained.During propagating, a weak interface between production layer and barrier may terminate the fracture or induce the formation of T-shape fracture.A barrier with lower elastic modulus may help a fracture penetrate through the interface and continue to propagate.The numerical results in this study are expected to provide some references for the perforating parameters optimization and fracturing design of horizontal wells.

Key words: perforation, double-fractures, interface, numerical simulation, hydraulic fracturing, horizontal well

中图分类号:

TE371

李志超,李连崇,唐春安. 水平井定向射孔裂缝起裂与穿层特征数值分析[J]. 石油与天然气地质, 2015, 36(3): 504-509. doi: 10.11743/ogg20150320 Li Zhichao,Li Lianchong,Tang Chun'an. Numerical analysis on hydraulic fracture initiation and penetration characteristics in directionally perforated horizontal wells[J]. Oil & Gas Geology, 2015, 36(3): 504-509. doi: 10.11743/ogg20150320

参考文献

[1] 范江, 张子香.利用水平井改善薄油层开发效果[J].石油学报, 1995, 16(2):56-62. Fan Jiang, Zhang Zixiang.Utilizing horizontal wells to improve the development effects in thin reservoirs[J].Acta Petrolei Sinica, 1995, 16(2):56-62.
[2] 陈勉, 金衍, 张广清.石油工程岩石力学[M].北京:科学出版社, 2008. Chen Mian, Jin Yan, Zhang Guangqing.Petroleum engineering rock mechanics[M].Beijing:Science Press, 2008.
[3] 朱海燕, 邓金根, 刘书杰, 等.定向射孔水力压裂起裂压力的预测模型[J].石油学报, 2013, 34(3):556-562. Zhu Haiyan, Deng Jingen, Liu Shujie, et al.A prediction model for the hydraulic fracture initiation pressure in oriented perforation[J].Acta Petrolei Sinica, 2013, 34(3):556-562.
[4] Li L C, Meng Q M, Wang S Y, Li G.A numerical investigation of the hydraulic fracturing behaviour of conglomerate in Glutenite formation[J].Acta Geotechnica, 2013, 8(6):597-618.
[5] Mofazzzal H M, Rahman M K.Numerical simulation of complex fracture growth during tight reservoir stimulation by hydraulic fraturing[J].Journal of Petroleum Science and Engineering, 2008, 60(2):86-104.
[6] 李连崇, 梁正召, 李根, 等.水力压裂裂缝穿层及扭转扩展的三维模拟分析[J], 岩石力学与工程学报, 2010, 29(1):3208-3215. Li Lianchong, Liang Zhengzhao, Li Gen, et al.Three dimensional numerical analysis of traversing and twisted fractures in hydraulic fracturing[J].Chinese Journal of Rock Mechanics and Engineering, 2010, 29(1):3208-3215.
[7] 赵立强, 刘飞, 王佩珊, 等.复杂水力裂缝网络延伸规律研究进展[J].石油与天然气地质, 2014, 35(4):562-569. Zhao Liqiang, Liu Fei, Wang Peishan, et al.A review of creation and propagation of complex hydraulic fracture network[J].Oil & Gas Geology, 2014, 35(4):562-569.
[8] 杨宇, 孙致学, 郭春华.用灰色模型预测水力压裂缝导流能力[J].石油与天然气地质, 2004, 25(1):111-114. Yang Yu, Sun Zhixue, Guo Chunhua.Prediction of conductivity of hydraulic fracturing induced fractures with gray models[J].Oil & Gas Geology, 2004, 25(1):111-114.
[9] Daneshy A A.Experimental investigation of hydraulic fracturing through perforations[J].Journal of Petroleum Technology, 1973, 25(10):1201-1206.
[10] 张广清, 陈勉.定向射孔水力压裂复杂裂缝形态[J].石油勘探与开发, 2009, 36(1):103-107. Zhang Guangqing, Chen Mian.Complex fracture shapes in hydraulic fracturing with orientated perforations[J].Petroleum Exploration and Development, 2009, 36(1):103-107.
[11] 周健, 陈勉, 金衍, 等.裂缝性储层水力裂缝扩展机理试验研究[J].石油学报.2007, 28(5):109-113. Zhou Jian, Chen Mian, Jin Yan, et al.Experimental study on propagation mechanism of hydraulic fracture in naturally fractured reservoir[J].Acta Petrolei Sinica, 2007, 28(5):109-113.
[12] 赵益忠, 曲连忠, 王幸尊, 等.不同岩性底层水力压裂裂缝扩展规律的模拟实验[J].中国石油大学学报(自然科学版), 2007, 31(3):63-66. Zhao Yizhong, Qu Lianzhong, Wang Xingzun, et al.Simulation experiment on prolongation law of hydraulic fracture for different lithologic formations[J].Journal of China University of Petroleum, 2007, 31(3):63-66.
[13] 赖枫鹏, 李治平, 郭艳东, 等.川东北碳酸盐气藏岩石渗透率变化实验[J].石油与天然气地质, 2012, 33(6):932-937. Lai Fengpeng, Li Zhiping, Guo Yandong, et al.Experiments on permeability change of carbonate gas reservoirs in the northeastern Sichuan Basin[J].Oil & Gas Geology, 2012, 33(6):932-937.
[14] 刘月田.各向异性油藏水平井开发井网设计方法[J].石油勘探与开发.2008, 35(5)619-624. Liu Yuetian.Methodology for horizontal well pattern design in anisotropic oil reservoirs[J].Petroleum Exploration and Development, 2008, 35(5):619-624.
[15] 汪玉梅.低渗透薄互储层水平缝缝间干扰规律[J].大庆石油学院院报, 2008, 32(4):56-60. Wang Yumei.Interference rules of horizontal fractures in thin reservoirs with low permeability[J].Journal of Daqing Petroleum Institute, 2008, 32(4):56-60.
[16] 傅尤校.水力压裂裂缝的延伸与储层的连续性[J].石油学报, 1984, 5(2):55-62. Fu Youxiao.Extension of hydraulic fractures and continuity of reservoir[J].Acta Petrolei Sinica, 1984, 5(2):55-62.
[17] Li L C, Tang C A, Li G, et al.Numerical simulation of 3D hydraulic fracturing based on an improved flow-stress-damage model and a parallel FEM technique[J].Rock Mechanics and rock engineering, 2012, 45(5):801-818.
[18] Ito T, Yamamoto K, Nagakubo S.Effect of anisotropic confining stresses on hydraulically-induced fracture propagation from perforated cased-hole in unconsolidated sands//The 45th US Rock Mechanics/Geomechanics Symposium.San Francisco:2011:26-29.
[19] 姜浒, 陈勉, 张广清, 等.定向射孔对水力裂缝起裂与延伸的影响[J].岩石力学与工程学报, 2009, 28(7):1321-1326. Jiang Hu, Chen Mian, Zhang Guangqing, et al.Impact of oriented perforation on hydraulic fracture initiation and propagation[J].Chinese Journal of Rock Mechanics and Engineering, 2009, 28(7):1321-1326.