叠前P-SV波裂缝参数提取方法

P-SV wave fracture parameter extraction from prestack data.

本文通过适用于单层HTI介质的P-SV波近似反射系数(RPS)公式,对RPS特征进行了分析,并与P-P波反射系数(RPP)进行对比;利用HTI介质中P-SV波近似反射系数公式推导出叠前单层HTI介质裂缝方位及密度反演公式,试验结果证明了文中的叠前P-SV波裂缝参数提取方法的合理性,并得出以下认识:①受HTI介质各向异性的影响,RPS随方位角的变化呈椭圆分布,并且椭圆的属性在一定程度上指示了裂缝的发育方向和发育强度;②各向异性系数ε对RPP没有影响,而γ对于RPP的影响最大;③各向异性系数ε、δ、γ都对RPS有影响,且γ的影响最大;④RPS对裂缝介质(HTI)的各向异性系数更加敏感,因此P-SV波叠前数据较P-P波数据包含更加丰富和准确的裂缝各向异性信息,可采用叠前P-SV波数据反演提取裂缝的方向和密度。模型正、反演试验证实,由裂缝方位角及发育强度反演公式得到的裂缝方位和强度结果精确度较高,因此可以根据本文方法计算并预测裂缝的方位及强度。

This paper analyzes the characteristics of RPS by P-SV approximate reflection coefficient(RPS) suitable for single HTI media,and compares these characteristics with those obtained by P-P reflection coefficient(RPP).Using the P-SV approximate reflection coefficient expression suitable for HTI media,we deduce the inversion expression to predict fracture azimuth and density of pre-stacked data.Results show the rationality of the fractured coefficient extraction method proposed in the paper.We get the following conclusions:①Influencing by the anisotropy of HTI media,RPSdistrib-utes as ellipse via the change of azimuth,whose property may indicate the fractured azimuth and intensity;②The anisotropic coefficientεis nothing to do with RPP,butγhas great influence to RPP; ③but all the 3anisotropic coefficientsε、δ、γ has certain influence to RPS,andγhas great influence to RPStoo;④RPSis more sensitive to fractured media(HTI),which means there must be more rich and correct fractured anisotropic information in P-SV pre-stacked seismic data.So we can inverse fractured azimuth and density from prestacked seismic data.Finally,the forward modeling and inversion results show that the accuracy is high enough to predict the fractured azimuth and density.