断层附近地应力扰动带宽度及其影响因素  

Width of stress disturbed zone near fault and its influencing factors

作　　者：翁剑桥 曾联波[4] 吕文雅[4] 刘奇[4,5] 祖克威[4,6] WENG Jianqiao;ZENG Lianbo;LYU Wenya;LIU Qi;ZU Kewei(Sichuan Keyuan Testing Center of Engineering Technology,Chengdu 610091,Sichuan,China;Key Laboratory of Shale Gas Evaluation and Exploitation of Sichuan Province,Chengdu 610091,Sichuan,China;Technical Innovation Center for Shale Gas Exploration and Development in Complex Structural Areas,Ministry of Natural Resources,Chengdu 610091,Sichuan,China;College of Geosciences,China University of Petroleum,Beijing 102249,China;Exploration and Development Research Institute of Jilin Oilfield Company,Songyuan 138000,Jilin,China;Research Institute of Exploration and Development,Zhongyuan Oilfield Company,Sinopec,Zhengzhou 450018,Henan,China)

机构地区：[1]四川省科源工程技术测试中心,四川成都610091 [2]页岩气评价与开采四川省重点实验室,四川成都610091 [3]自然资源部复杂构造区页岩气勘探开发工程技术创新中心,四川成都610091 [4]中国石油大学(北京)地球科学学院,北京102249 [5]吉林油田勘探开发研究院,吉林松原138000 [6]中石化中原油田分公司勘探开发科学研究院,河南郑州450018

出　　处：《地质力学学报》2020年第1期39-47,共9页Journal of Geomechanics

基　　金：石油化工联合基金项目(U1663203);国家科技重大专项(2016ZX05003-001)

摘　　要：在建立正断层模型的基础上,利用三维有限元数值模拟方法研究了断层附近地层中的地应力变化规律。其结果表明,由于断层活动,在断层附近普遍发育应力扰动带;在应力扰动带范围内,地应力方向和大小发生明显的变化,断层中部附近应力值普遍较低,而断层端部的应力值通常异常增大。应力扰动带的分布范围主要受断层规模的控制,与断裂带的岩石力学性质、断层走向、断层面形态和边界应力条件等因素也密切相关。随断层长度和断距逐步增大,应力扰动带的宽度相应增加。断裂带的岩石越破碎,其岩石弹性模量越低,断层对地应力的影响宽度越大。断层走向与区域最大水平主应力方向越接近垂直、断距与断层长度的比值越大,区域内的差应力越大,则扰动带宽度与断层规模的比值也越大。选择渤海湾盆地BZ-X油田进行验证,在建立油田实际三维地质模型基础上,根据边界应力条件,利用三维有限元方法对沙河街组二段的地应力分布进行了数值模拟计算。根据断层周围的地应力变化,确定了应力扰动带的分布范围,断层附近应力扰动带宽度的分布规律与正断层模型分析结果相一致。3D normal fault models in a triaxial crustal stress state were established in finite element simulation software to study the characteristics of in-situ stress in the fault developed areas.Simulated data show that the disturbed zones of in-situ stress widely exist in the surrounding rocks due to the fault movement.The principle stress direction in the disturbed zones is obviously deviated from the background stress state.The stress value is lower near the middle of the faults,while the fault ends are the abnormally high stress realm.Based on the analysis results,the distribution of stress disturbed zone is mainly decided by the fault scale.Width of stress disturbed zone proportionally goes up as fault length and displacement increase simultaneously.Rock mechanism,fault strike,shape of fault plane and background stress state affect the width of stress disturbed zone by changing the ratio of width to fault length(W-L).More intensely fractured fault rock along with higher angle between fault strike and background maximum horizontal principle stress direction,greater ratio of fault displacement to fault length(D-L),larger differential stress,leads to higher W/L value.The conclusions are verified in BZ-X Oilfield,Bohai Bay Basin.Building a 3D geologic model on the basis of actual structure relief and regional stress state,the in-situ stress in 2nd member of Shahejie Formation was calculated with the finite element method.The distribution of stress disturbed zones near faults is made clear by analyzing variation of in-situ stress state in surrounding rocks.The width of stress disturbed zones changes regularly as predicted in the law above.Both stress value and orientation,is notably changed in disturbed zones,which could affect artificial fracture propagation and well pattern deployment significantly.

关 键 词：断层 地应力 扰动带宽度 影响因素 有限元数值模拟 BZ-X油田 

分 类 号：TU45[建筑科学—岩土工程] P553[建筑科学—土工工程]