衰减补偿的黏弹性最小二乘逆时偏移  

Attenuation compensation for viscoelastic least-squares reverse time migration

作　　者：刘玉敏[1] 李雪松[2] 张伟[3] LIU YuMin;LI XueSong;ZHANG Wei(School of Electrical Engineering and Information,Northeast Petroleum University,Daqing 163318,China;Exploration and Development Research Institute of Daqing Oil Field Company Limited,Daqing 163712,China;College of Earth Science,Northeast Petroleum University,Daqing 163318,China)

机构地区：[1]东北石油大学电气信息工程学院,大庆163318 [2]大庆油田有限责任公司勘探开发研究院,大庆163712 [3]东北石油大学地球科学学院,大庆163318

出　　处：《地球物理学进展》2021年第1期222-229,共8页Progress in Geophysics

基　　金：国家自然科学基金项目(41574117);黑龙江省杰出青年科学基金项目(JC2016006)联合资助。

摘　　要：地震勘探是发现和认识油气藏的重要方法,随着国内油气勘探领域、勘探对象的日趋复杂化,油气勘探迫切需求地震成像的精准度、分辨率和保真度的大幅度提升.相比于常规逆时偏移方法,最小二乘逆时偏移成像有较少的伪像,成像振幅均衡,成像分辨率高.目前常用弹性最小二乘逆时偏移方法来对地下介质进行成像.但由于地下介质通常表现出黏弹性性质,在含油气地层中表现尤为明显,若忽略地下介质的吸收衰减作用,地震波传播中的振幅衰减和频散累积将会影响成像的振幅和相位,进而降低成像分辨率,致使地下构造定位不准.本文基于标准线性体模型的黏弹性波动方程,提出一种衰减补偿的黏弹性最小二乘逆时偏移成像方法,推导了准确的黏弹性最小二乘理论框架下的偏移算子、反偏移算子、步长,并给出了算法的数值实现流程.通过对层状模型和Marmousi模型进行测试,得到本文提出的黏弹性波最小二乘逆时偏移方法的成像结果和收敛速度,并与其他方法的测试效果进行了对比.结果表明,黏弹性最小二乘逆时偏移方法能够准确地归位包含强衰减的多分量地震记录,能够有效避免弹性波最小二乘逆时偏移成像错误的反射层位置,压制成像噪声,收敛速度快,成像精度高.Seismic exploration is an important method for discovering and understanding hydrocarbon reservoirs. With the increasing complexity of domestic hydrocarbon exploration field and exploration objects,hydrocarbon exploration urgently requires a great improvement in the accuracy, resolution and fidelity of seismic imaging.The least squares reverse time migration images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the conventional reverse time migration images.At present, the elastic least-squares reverse time migration approach is commonly used to image underground media.But the earth usually behaves the viscoelastic properties, especially in the petroliferous formation. If these attenuation effects are ignored, amplitude attenuation and dispersion accumulated in the wave propagation will lead to distortion of amplitude and phase of seismic image with lower image resolution. And the imaging resolution will be reduced, resulting in inaccurate positioning of underground structures. Based on the viscoelastic wave equation of Standard Linear Solid(SLS) model, this paper propose a viscoelastic Least-Squares Reverse Time Migration(LSRTM) approach. In this paper, the exact migration operator, de-migration operator and step size under the framework of viscoelastic least square theory are derived, and the numerical implementation flow of the algorithm is given.By testing the layered model and Marmousi model, the imaging results and convergence rate of the viscoelastic wave inverse time migration method proposed in this paper are obtained, and the results are compared with those of other methods.Numerical tests show that the viscoelastic LSRTM can accurately image the multi-component seismic recordings with strong attenuation and can effectively avoid the false reflection events of elastic LSRTM approach.This method have fast convergence speed and high imaging accuracy.

关 键 词：多分量地震资料 最小二乘逆时偏移 黏弹性 标准线性体模型 

分 类 号：P631[天文地球—地质矿产勘探]