叠前重加权L_(1)范数稀疏约束的地震反演方法  

Prestack seismic inversion with reweighted L_(1)-norm sparse constraints

作　　者：赵云[1,2] 文晓涛 尹川[3] 韩文明 李陈龙 ZHAO Yun;WEN Xiaotao;YIN Chuan;HAN Wenming;LI Chenlong(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu,Sichuan 610059,China;College of Geophysics,Chengdu University of Technology,Chengdu,Sichuan 610059,China;CNOOC International Energy Services(Beijing)Co.,Ltd.,Beijing 100010,China)

机构地区：[1]成都理工大学油气藏地质及开发工程重点实验室,四川成都610059 [2]成都理工大学地球物理学院,四川成都610059 [3]中海石油国际能源服务(北京)有限公司,北京100010

出　　处：《石油地球物理勘探》2023年第6期1398-1409,共12页Oil Geophysical Prospecting

基　　金：中国海洋石油集团有限公司“十四·五”重大科技项目“‘两岸一带’重点区勘探开发地球物理关键技术”(KJGG2022‐0903)资助。

摘　　要：传统稀疏约束反演的低稀疏性伪层和低分辨率导致薄层识别难度大。为此,提出了一种基于重加权L_(1)范数稀疏约束的叠前地震反演方法,即将地层反射系数与重加权矩阵的元素相结合,对地层反射系数进行重加权处理,优化、构建反演目标函数,并利用交替方向乘子算法(ADMM)将含有多个参数的非线性反演目标函数转化为多个易于求解的单参数的线性子问题,同时引入软阈值收缩算法(ISTA)求解子问题中存在的混合范数最优解。与仅考虑反射边界位置信息的传统L_(1)范数约束不同,重加权的L_(1)范数挖掘了岩层边界的反射振幅信息,可以更充分地利用L_(1)范数的稀疏性,通过叠前地震反演获得更精确的地层速度边界和密度边界,减弱利用传统L_(1)范数反演结果中可能存在的速度伪层现象。模型测试和工区实测数据应用均表明,所提方法获取的纵波速度、横波速度和密度剖面上边界更准确,分辨率更高,对薄层识别能力更强,极大地减弱了伪层现象,可为后续其他地球物理参数的预测提供更准确的资料基础。Low sparsity pseudo‐layers and low resolution of traditional sparse‐constrained inversion lead to difficulty in thin‐layer identification.To this end,we propose a prestack seismic inversion method based on reweighted L_(1)‐norm sparse constraints,namely to combine the reflection coefficients of the formation with the elements of the reweighted matrix,and the reflection coefficients are further reweighted to optimize and construct the inversion objective function.In addition,the alternating direction method of multipliers(ADMM)is used to transform the nonlinear inversion objective function containing multiple parameters into multiple easily solvable single‐parameter linear subproblems,and iterative shrinkage thresholding algorithm(ISTA)is introduced to solve the mixed norm optimal solution of the subproblems.Unlike the traditional L_(1)‐norm sparse constraints,which only consider the position information of the reflection boundary,the reweighted L_(1)‐norm exploits the amplitude information of the reflection boundary,which can more fully utilize the sparsity of the L_(1)‐norm to obtain more accurate formation velocity boundary and density boundary through the prestack seismic inversion and weaken the velocity pseudo‐layer phenomenon existing in the traditional L_(1)‐norm inversion results.The model test and the application of the measured data in the field data demonstrate that the profile boundaries of P‐and S‐wave velocities and density obtained by the proposed method are more accurate,with higher resolution,better identification ability for thin layers,and the pseudo‐layer phenomenon is greatly reduced.It can provide a more accurate data basis for the subsequent prediction of other geophysical parameters.

关 键 词：重加权 叠前地震反演 稀疏性 分辨率 薄层识别 

分 类 号：P631[天文地球—地质矿产勘探]