Moment tensor inversion method from borehole data constrained by shear-tensile source model
TANG Jie1, LI Cong1, LIU Yingchang1, CHEN Xueguo2
1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China; 2. Exploration and Development Research Institute, SENOPEC Shengli Oilfield, Dongying, Shangdong 257015, China
Abstract:Hydraulic fracturing microseismic data can be used to estimate moment tensor and study the azimuth and detailed characteristics of fractures,which have a great effect on depicting the fracture system inside the reservoir.Moment tensor inversion is a linear inversion method.It is not sufficient to invert all moment tensors from single well data.Therefore,additional constraints,near-field data or simplified source models should be considered.Pertinently,the shear-tensile source constrained inversion was studied in this paper.It uses nonlinear inversion method to limit the moment tensor to describing the shear-tensile source,in order to reduce inversion parameters and enhance robust.Firstly,the principle of trust-domain microseismic source mechanism inversion constrained by shear-tensile source was introduced.And then,the application effect of the method was tested using the theoretical model records of single well,double wells and three wells under different tensile angle conditions.The following conclusions were drawn.The moment tensor inversion and the shear-tensile source constrained inversion based on the data of three wells achieved good results when the test data didn't contain any noise.When the data of few wells were used,the moment tensor inversion couldn't obtain reasonable results.When the test data contained noise,the shear-tensile source constrained inversion achieved better anti-noise performance,and the inversion effect based on the data of three wells is better than that based on single-well data.The amplitudes derived by shear-tensile source inversion are more selective.
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