弹性波阻抗在时移地震中的应用分析

Application and analysis of elastic impedance in time-lapse seismolgy

常规声波波阻抗由于缺乏横波的信息,使得它对于流体的变化很不敏感,而弹性波阻抗反演,除了与纵波速度,密度有关之外,还与横波速度、入射角度有关,由于考虑了AVO(Amplitude Variation with Offset)效应,使得对流体和岩性的预测能力增强.本文将弹性波阻抗反演应用于时移地震中,采用AVA(Amplitude Variation with Angle)约束稀疏脉冲反演来进行弹性波阻抗反演,得到纵横波阻抗等弹性参数,通过交会图分析,将弹性参数转换为油藏参数,如预测含水饱和度的变化,通过本方法可增强对储层流体的预测,提高储层管理能力.

Acoustic Impedance is the product of compressional velocity and density. It is insensitive to the changes in fluid. This is unfavorable to the detection of oil and gas. Elastic Impedance is not only related to compressional velocity and density, but also related to shear velocity and an angle of incidence. As a result of considering AVO effect, Elastic Impedance is more capable of detecting of fluid and lithology than acoustic Impedance. Apply the method of elastic impedance inversion to time-lapse seismic, use AVA constrained sparse spike inversion to process elastic impedance inversion, and use cross-plot technique to predict changes in dynamic reservoir properties, such as water saturation. Estimates of saturation allow integration of time-lapse seismic with elastic impedance inversion to improve reservoir fluid-flow prediction and enhance reservoir management decisions.