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.
shale gascasing deformationmicroseismicfault slippageseismic parametersamount of fault slip
万方数据
维普
