基于动校正前CRP道集的多波联合AVO反演新方法

A New Joint AVO Inversion Method Based on the CRP Before NMO Correction

叠前AVO反演可以得到地层的弹性信息,继而进行地层岩性和流体类型识别。与速度信息相比,弹性模量信息更有利于储层描述。因此,本文采用叠前AVO反演方法直接反演得到纵波模量反射系数、横波模量反射系数和密度反射系数,联合纵波(PP)资料和转换横波(PS)资料进行AVO反演提高反演结果的精度和稳定性。常规AVO反演方法所采用的数据都是动校正后的CRP道集,动校正处理引入的动校正拉伸效应会影响反演效果,降低反演精度,尤其是密度的反演结果会受到较大影响。本文采用动校正前的CRP道集进行联合AVO反演,在反演过程中引入贝叶斯理论,从而提高反演的稳定性和精度。理论模型试算结果表明,本文提出的反演方法具有更好的稳定性、更高的精度以及更强的抗噪能力。

Prestack amplitude versus offset(AVO)inversion is a practical method to obtain the elastic information directly,which is usually applied in the lithology and fluid prediction.Compared with velocity,elastic modulus can be more instructive for reservoir characterization.Thus,P-wave modulus reflection coefficient,S-wave modulus reflection coefficient and density reflection coefficient will be inverted in this paper.By combining PP and PS seismic data,we can improve the accuracy of AVO inversion.Current methods of AVO inversion use the seismic data after NMO correction.However,NMO stretch caused by NMO correction will introduce error into the inversion.This paper develops an improved PP and PS AVO joint inversion method using the seismic data before NMO correction to invert the parameters more precisely.The inversion method is based on linearized approximation of the Zoeppritz equation and Bayesian parameter estimation theory.Synthetic data tests show that the method can generally invert more accurate modulus and density.