基于弹性阻抗的高精度纵横波速比直接反演方法研究与应用  

Study and application of high-precision direct inversion method of P-to-S-wave velocity ratio based on elastic impedance

作　　者：刘应天 李勇[1,2,3] 廖章权[1,2] 胡睿[1,2] 贺东宣 LIU YingTian;LI Yong;LIAO ZhangQuan;HU Rui;HE DongXuan(School of Geophysics,Chengdu University of Technology,Chengdu 610059,China;Key Laboratory of Earth Exploration and Information Technology of the Ministry of Education(Chengdu University of Technology),Chengdu 610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering(Chengdu University of Technology),Chengdu 610059,China)

机构地区：[1]成都理工大学地球物理学院,成都610059 [2]地球勘探与信息技术教育部重点实验室(成都理工大学),成都610059 [3]油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059

出　　处：《地球物理学进展》2024年第3期1152-1163,共12页Progress in Geophysics

摘　　要：纵横波速比作为描述地层属性的重要参数,能有效地划分岩性与识别储层.常规方法中,通常使用AVO技术来反演P波速度和S波速度,然后间接计算纵横波速比.但间接计算可能会造成纵横波速比提取时精度的不足,导致计算结果出现累积误差.为了克服累积误差,本文首先推导出反射系数与纵横波速比之间的直接关系,基于此建立了纵横波速比的弹性阻抗方程(LEI方程).然后使用两类典型的AVO砂页岩模型验证了LEI方程的正演精度,进一步研究发现,纵横波速比对k值的变化十分敏感.因此,构建了一种基于LEI方程的多条件约束的叠前反演算法.经Marmousi2模型试算和川西拗陷-XC构造带工区资料应用表明,该方法有效地提高了纵横波速比反演的精度,提供了一种从叠前地震资料中提取纵横波速比参数的方法.As an important parameter for describing geological properties,P-to-S-wave velocity ratio can effectively distinguish lithology and identify reservoirs.However,conventional methods usually use AVO technology to invert P-wave and S-wave velocities,and then indirectly calculate P-to-S-wave velocity ratio.The indirect calculations may result in the insufficient accuracy of extracting P-to-S-wave velocity ratio and lead to cumulative errors in the calculation results.To overcome this issue,this study first derives the direct relationship between reflection coefficients and P-to-S-wave velocity ratio,and establishes the Linear Elastic Impedance(LEI)equation for P-to-S-wave velocity ratio based on the derived relationship.Then,two typical AVO sand-shale models are used to verify the forward accuracy of the LEI equation.Further research shows that P-to-S-wave velocity ratio is very sensitive to k-values.So,a pre-stack inversion algorithm with multiple constraints based on the LEI equation is proposed.Results from testing on the Marmousi2 model and field data from the Chuanxi fold-XC structure indicate that the proposed method effectively improves the accuracy of P-to-S-wave velocity ratio inversion and provides a method for extracting P-to-S-wave velocity ratio parameters from pre-stack seismic data.

关 键 词：纵横波速比 累积误差 弹性阻抗 模型分辨矩阵 叠前反演 

分 类 号：P631[天文地球—地质矿产勘探]