基于震源机制的断层滑移量计算方法  

Calculation method of the amount of fault slip based on the source mechanism

作　　者：刘怀亮 樊子潇 刘宇 连威 席岩 张小军 LIU Huailiang;FAN Zixiao;LIU Yu;LIAN Wei;XI Yan;ZHANG Xiaojun(Beijing Huamei Century International Technology Co.,Ltd.,Beijing 102299,China;China University of Petroleum(Beijing),Beijing 102249,China;China University of Petroleum(Beijing)Karamay Campus,Karamay,Xinjiang 834000,China;Beijing Industry University,Beijing 100124,China)

机构地区：[1]北京华美世纪国际技术有限公司,北京102299 [2]中国石油大学(北京),北京102249 [3]中国石油大学(北京)克拉玛依校区,新疆克拉玛依834000 [4]北京工业大学,北京100124

出　　处：《世界石油工业》2024年第5期40-47,共8页World Petroleum Industry

摘　　要：四川页岩气区块在开发过程中套管变形问题严重,主要由断层滑移引起,可通过微地震监测识别断层,但是基于微地震参数计算断层滑移量的方法还较为缺乏。基于震源机制基本方程,建立断层滑移量的计算方法,以长宁某井在压裂过程中监测到的微地震信号为样本,采用最大似然估计法对计算过程中所需震源参数b值进行精确计算,得到的断层半径和滑移量与现场结论相符,在此基础上分析了微地震参数和地层参数对断层滑移量的影响。研究结果表明:断层滑移量与地层性质、微地震矩震级和微地震b值有关。地层弹性模量越低,断层内摩擦系数越小,断层滑移量越大;断层滑移量随矩震级增加呈指数关系增加;b值越接近1,断层滑移量越大,且矩震级的变化对断层滑移量的影响越明显。若产生矩震级2.5以上微地震事件或微地震b值异常降低至1附近时,应及时调整压裂参数,降低压裂强度以预防断层发生滑移。该研究成果可对预警断层滑移风险提供参考。Casing deformation is a serious problem in the development of shale gas blocks in Sichuan Province.The main mechanism of casing deformation fault slip,and microseismic signal monitoring is the main means to identify faults.However,the method of calculating fault slip based on microseismic parameters is still lacking.In this paper,based on the basic equation of focal mechanism,a calculation method of fault slip is established,and the microseismic signal detected in the fracturing process of a well in Changning is taken as sample.The maximum likelihood estimation method is used to accurately calculate the focal parameter b value required in the calculation process.The calculated fault radius and slip amount are in agreement with the field conclusions.On this basis,the effects of microseismic and stratigraphic parameters on the amount of fault slip are analyzed.The results show that the slip of fault is related to the formation properties,microseismic moment magnitude and microseismic b value.The lower the formation elastic modulus,the smaller the internal friction coefficient and the larger the slip amount of the fault.The slip of fault increases exponentially with the increase of moment magnitude.The closer the b value is to 1,the greater the slip amount of the fault,and the more obvious the influence of moment magnitude change on the slip amount of the fault.If a microseismic event with a moment magnitude of more than 2.5 occurs or the microseismic b value is abnormally reduced to around 1,the fracturing parameters should be adjusted in time to reduce the fracturing intensity to prevent fault slippage.The results of this research can inform early warning of the risk of fault slip.

关 键 词：页岩气 套管变形 微地震 断层滑移 震源参数 断层滑移量 

分 类 号：TE37[石油与天然气工程—油气田开发工程]