Amplitude variation with offset and azimuth inversion to predict and evaluate coal seam fracture parameters  

作　　者：Haibo WU Shujie ZHU Qinjie LIU Shouhua DONG Yanhui HUANG Pingsong ZHANG 

机构地区：[1]School of Earth and Environment,Anhui University of Science and Technology,Huainan 232001,China [2]Institute of Energy,Hefei Comprehensive National Science Center(Anhui Energy Laboratory),Hefei 230051,China [3]Xi’an Research Institute,China Coal Technology&Engineering Group,Xi’an 710076,China [4]School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221116,China [5]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China

出　　处：《Frontiers of Earth Science》2023年第2期505-513,共9页地球科学前沿（英文版）

基　　金：supported by the University Synergy Innovation Program of Anhui Province(Nos.GXXT-2021-016 and GXXT-2019-029);the National Natural Science Foundation of China(Grant No.41902167);the Institute of Energy,Hefei Comprehensive National Science Center(No.21KZS215).

摘　　要：Amplitude variation with offset and azimuth(AVOA)inversion is a mainstream method for predicting and evaluating fracture parameters of conventional oil and gas reservoirs.However,its application to coal seams is limited because of the specificity of the equivalent media model for coal—also,the traditional seismic acquisition system employed in coal fields falls within a narrow azimuth.In this study,we initially derived a P‒P wave reflection coefficient approximation formula for coal seams,which is directly expressed in terms of fracture parameters using the Schoenberg linear-slide model and Hudson model.We analyzed the P‒P wave reflection coefficient’s response to the fracture parameters using a two-layer forward model.Accordingly,we designed a twostep inversion workflow for AVOA inversion of the fracture parameters.Thereafter,high-density wide-azimuth pre-stack 3D seismic data were utilized for inverting the fracture density and strike of the target coal seam.The inversion accuracy was constrained by Student’s tdistribution testing.The analysis and validation of the inversion results revealed that the relative fracture density corresponds to fault locations,with the strike of the fractures and faults mainly at 0°.Therefore,the AVOA inversion method and technical workflow proposed here can be used to efficiently predict and evaluate fracture parameters of coal seams.

关 键 词：equivalent media model fracture density and strike AZIMUTH Student’s t-distribution 

分 类 号：P31[天文地球—固体地球物理学]