摘要
海底多波地震勘探利用海底电缆(OBC)采集海底各岩层的弹性波的多波多分量信息。在利用振幅随偏移距变化(AVO)进行弹性参数反演中,这些分量对反演所作的贡献是不同的,体现在各反射波的反射系数与弹性参数的信息量及其组合关系的关联程度是不同的。利用波场正演技术分析研究海底多波地震资料中蕴含弹性参数的信息,有助于充分利用海底多波地震资料提高AVO反演弹性参数的可靠性。本文在前人工作的基础上,应用计算反射系数的Aki近似公式,进行海底多波多分量合成数据蕴含弹性参数的定量分析,确定哪些弹性参数或它们的组合关系能最佳地从AVO资料中反演得到。文中考虑的弹性参数是速度及密度的相对扰动量,在时间域内对反射系数的正演计算公式进行线性化,获取反演的灵敏度矩阵,并利用SVD计算反演灵敏度矩阵的特征值及特征向量,继而分析弹性参数反演的信息量。由计算结果可知海底压力波场和质点速度分量资料蕴含的弹性参数的信息要比常规海上地震资料多。
Multiwave multicomponent seismic data of sea bottom formations are obtained by multiwave seismic exploration using ocean bottom cable. In the inversion of elastic parameter by AVO, the components make different contributions to the inversion. To speak exactly, the reflection coefficient and elastic parameter information of each reflection wave together with their correlation degree are different. To analyse elastic parameter informations contained in sea bottom multiwave seismic data by wave field forward technique very favours improving the AVO inversion of elastic parameters with the use of sea bottom multiwave seismic data. Aki approximate formula for reflection coefficient estimation is taken to analyse quantitatively the elastic parameter informations contained in sea bottom synthetic multiwave multicomponent seismic data, and to determine which elastic parameters or their combination can be derived inversively from AVO data optimally. Elastic parameters involved in the paper are the relative perturbation of velocity and density. In time domain, the forward estimation formula of reflection coefficient is linearized to have inversive sensitivity matrix, whose eigenvalue and eigenvector can be obtained by using SVD. The information volume of elastic parameters are analysed finally. The analysis results show that the sea bottom pressure wave field and particle velocity component data have more elastic parameter informations than ordinary offshore seismic data, and that the relative perturbations of P wave velocity, S wave velocity and density can be inversively calculated desirably.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2000年第1期56-63,共8页
Oil Geophysical Prospecting
基金
国家 8 6 3计划!"海上多波地震勘探技术"( 82 0 -0 5 -0 2 -0 3)项目资助
关键词
海底地震勘探
AVO
弹性参数
定量分析
地震勘探
sea bottom seismic exploration, multiwave multicomponent, AVO, elastic parameter, quantitative analysis, inversion, velocity, density
