混合地震反演技术及其在水合物勘探中的应用

Hybrid seismic inversion and its application in hydrate exploration

(1.中国科学院海洋研究所,山东青岛266071；2.中国科学院海洋地质与环境重点实验室，山东青岛266071；3.中国石油大学，山东东营257061；4.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257002)

Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China

在没有钻井资料的勘探地区，人们期望能快速准确地反演出各种属性参数。虽然叠后反演简单易行，但仅能反演出波阻抗信息；而叠前反演能够提供较多的属性参数，但运算量巨大。为将叠前和叠后的优势有机地结合起来，人们提出了混合反演的方法。混合反演法的基本原理是：首先采用基因遗传算法，在叠前数据上根据勘探要求任意选择控制点进行波形反演，建立弹性模型；然后利用AVO处理方法得到P波和伪S波剖面；最后，在P波和伪S波数据体上，以弹性模型作为低频背景趋势，进行叠后约束稀疏脉冲反演，得到P波阻抗和S波阻抗剖面以及纵横波速度比、泊松比和拉梅参数等地震属性参数。利用混合反演法对我国南海北部的0101线进行了反演，得到了品质较高的多种属性剖面，并对水合物的赋存情况进行了分析。

In a new exploration area, we often expect to inverse various seismic attributes quickly and exactly for reservoir prediction. Although the poststack inversion is simple and quite easy in operation, it can only obtain the acoustic impedance. The prestack inversion can provide many attributes, but it has a disadvantage of large amount of calculation. In order to combine the advantages of prestack and poststack inversion, the hybrid seismic inversion is proposed, which can perform a large volume of seismic data within a reasonable time interval. The principles of hybrid seismic inversion are that 1) the genetic algorithm (GA) is applied to inverse waveform to prestack data at arbitrary controlling points by the requirement of exploration, and establish elastic models; 2) the AVO processing is used to generate P-wave and pseudo S-wave profiles; and 3) the elastic models are used as the background trend of low-frequency impedance for poststack constrained sparse impulse inversion on P-wave and S-wave volumes, with some attributes being obtained from it, including P-wave and S-wave impedance profiles, vp/vs, and Lame’s constant. In addition, the hybrid seismic inversion is applied to line 0101 in the northern South China Sea, getting many high-quality attribute profiles. Finally, the occurrence of gas hydrate is also discussed.