基于OVT域地震数据的叠前AVOA裂缝密度反演  

Fracture density estimation using an amplitude-versus-offset-and-azimuth inversion based on prestack seismic data in the offset vector tile domain

作　　者：魏欣伟[1] 薛姣[2,3] 罗霞 WEI Xinwei;XUE Jiao;LUO Xia(Geophysical Research Institute,Sinopec Shengli Oilfield Company,Dongying 257000,China;Institute of Geophysics and Geomatics,China University of Geosciences,Wuhan 430074;Hubei Subsurface Multiscale Image Key Laboratory,Wuhan 430074,China)

机构地区：[1]中国石油化工股份有限公司胜利油田分公司物探研究院,山东东营257000 [2]中国地质大学(武汉)地球物理与空间信息学院,湖北武汉430074 [3]地球内部多尺度成像湖北省重点实验室,湖北武汉430074

出　　处：《石油物探》2021年第5期816-825,共10页Geophysical Prospecting For Petroleum

基　　金：国家科技重大专项“渤海湾盆地济阳坳陷致密油开发示范工程”(2017ZX05072)资助。

摘　　要：基于炮检距向量片(OVT)域地震数据的振幅随偏移距和方位角变化(AVOA)裂缝参数反演,充分利用了OVT道集中丰富的叠前各向异性信息,能够提高裂缝储层预测的有效性。基于裂缝等效介质理论,分别给出了含油和含气条件下反射系数与裂缝密度之间的关系,推导出不同方位地震道集差异与裂缝密度之间的矩阵关系,建立了AVOA裂缝密度反演方程;同时建立了OVT域地震数据分方位入射角提取、波形匹配时差校正和AVOA反演的裂缝密度估计流程。中国SK地区多层系发育致密砂岩含油储层,该地区OVT域地震数据AVOA裂缝密度反演结果显示裂缝发育展布特征与断裂带分布相一致;裂缝密度反演结果与测井资料相吻合,表明所提出的方法在裂缝密度反演和储层预测中的准确性与应用前景,同时为研究区今后的裂缝储层预测和开发提供了依据。The estimation of fracture density using an amplitude-versus-offset-and-azimuth(AVOA)inversion based on prestack seismic data in the offset vector tile(OVT)domain can improve the prediction efficiency of fractured reservoirs because OVT gathers contain valuable information on anisotropy.In this paper,we present the relationship between the reflection coefficient and fracture density for oil-saturated and gas-saturated fractured media,respectively,based on the equivalent medium theory.We derive a matrix equation that relates the differences in seismic traces with different azimuths and fracture densities,and introduce the AVOA inversion approach.We propose a fracture estimation process that entails an azimuth-incident angle gather extraction,a time correction using the waveform matching method,and an AVOA inversion.The SK area is located in middle China and is characterized by oil-saturated tight sandstone reservoirs with fractures.We performed AVOA inversion to estimate the fracture density using field seismic data in the OVT domain in this area.The distribution of fractured reservoirs was consistent with the distribution of faults.The results in terms of fracture density agree with the well log data,thereby demonstrating the accuracy and potential of AVOA inversion in fracture density estimation and fractured reservoir prediction.Moreover,the estimation of fracture parameters is crucial for the exploration and exploitation of hydrocarbon reservoirs.

关 键 词：OVT域 裂缝等效介质 各向异性 叠前AVOA反演 裂缝密度 储层预测 

分 类 号：P631[天文地球—地质矿产勘探]