一种频率域AVO油气检测方法

频率域AVO分析指通过时频转换将地震数据转换到频率域,再对目的层段地震振幅(能量)随频率以及炮检距的变化情况进行研究。本文针对苏里格气田低渗透致密砂岩薄气层在时间域难以识别的问题,介绍了频率域AVO流体识别技术。首先从岩石物理分析入手,根据苏里格气田的实际地质情况,利用统计手段得到基于频散的频率域AVO流体识别理论算法;其次,利用S变换得到较为准确的频率域数据,利用实际地震叠后资料进行储层振幅(能量)随频率变化的分析;最后,针对地震叠前资料进行储层振幅(能量)随频率以及炮检距变化的研究。本文算法的实际应用结果表明:在地震频带内,薄层低孔致密砂体的调谐效应不可能产生明显的频率响应异常,高频段较强的频散效应才是造成频率响应异常的原因。

A frequency AVO method for hydrocarbon detection

Frequency AVO analysis studies amplitude(energy) variation of target stratum versus frequency and offset after time-frequency transform of seismic data.It is difficult to identify tight thin gas reservoir on seismic data in time domain.In this paper,we introduce an approach for fluid identification on seismic data in frequency domain.Firstly,we start with rock physics analysis,and use statistic method to deduce the theory algorithm of AVO analysis in frequency domain for fluid identification based on velocity dispersion.Then,we do S transform to obtain more accurate data in frequency domain to analyze amplitude variation with frequency in reservoir on post-stack seismic data.In the end,we analyze amplitude variation with frequency and offset on seismic pre-stack data of reservoir.Applications of this method show that tuning effect of tight,thin sand with low porosity cannot cause abnormal frequency response in seismic frequency band,only frequency dispersion in high frequency band causes abnormal response.