Fracture prediction using prestack Q calculation and attenuation anisotropy
叠前地震衰减各向异性的裂缝预测方法及应用(英文)作者机构:中国石油大学油气资源与探测国家重点实验室北京102249 中国石油大学CNPC物探重点实验室北京102249
出 版 物:《Applied Geophysics》 (应用地球物理(英文版))
年 卷 期:2015年第12卷第3期
页 面:432-440,469页
核心收录:
学科分类:081801[工学-矿产普查与勘探] 081802[工学-地球探测与信息技术] 08[工学] 0818[工学-地质资源与地质工程]
基 金:supported in part by National Science&Technology Major Project(Grant No.2011ZX05019-008) the National Basic Research Program of China(973 Program)(Granted No.2013CB228600) Science Foundation of China University of Petroleum,Beijing(Granted No.KYJJ2012-05-10)
主 题:Fracture attenuation quality factor MST CMP gather
摘 要:The analysis of fractured reservoirs is very important to hydrocarbon exploration. The quality factor Q is a parameter used to characterize the attenuation of seismic waves in subsurface media. Q not only reflects the inherent properties of the medium but also is used to make predictions regarding reservoir fractures. Compared with poststack seismic data, prestack seismic data contain detailed stratigraphic information of seismic attributes and data inversion in reservoirs. The extraction of absorption parameters from prestack data improves the accuracy of attenuation estimates. In this study, I present a new method for calculating Q based on the modified S transform (MST) using common midpoint (CMP) preprocessed gathers. First, I use the MST with adjustable time-frequency resolution to carry out a high-precision time-frequency analysis of prestack CMP gathers and derive the calculation formula for the improved S transform-based frequency spectrum ratio method. Then, I use the energy density ratio to calculate the slope of the frequency spectrum ratio instead of the conventional amplitude ratio. Thus, I establish the relation between the slope of the spectrum ratio and offset as well as eliminate the offset effect by multichannel linear fitting, obtaining accurate Q values from seismic prestack data. Finally, I use the proposed prestack Q extraction method to study the fractured reservoir in Qianjin burried hill and P-wave absorption and attenuation anisotropy with good results in the fracture characterization.