用P-SV波AVO特性判别油气异常
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摘要
地震反射波振幅随炮检距变化的规律（AVO）不仅P波存在，而且P－SV波也同样具有AVO特征。在某些条件下，P－SV波的AVO特征更明显、本文先从Zoeppritz方程出发，利用研究区的物性参数，分析了含气砂岩顶、底界的AVO特性。再用射线追踪方法对实际资料进行由X－t域到θ-x域转换以后，同一层位的含气和非含气部位振幅变化差异十分明显。在包络差剖面上可见含气层周围有明显的振幅异常。据此，可在研究区内利用P－SV波的AVO特性判别油气异常。
AVO phenomenon of seismic reflection waves can be seen in both P wave andP-SV wave. Under some conditions,P-SV wave may show more obvious AVO phe-nomenon than P wave. AVO characteristics of P-SV waves from top and bottom of gas-bearing sandstone has been analysed with the use of Zoeppritz equation and re-lated petrophysical parameters. Having converted seismic data from x-t domain to θx domain by ray tracing method,we can see very obvious amplitude-variation differ-ence between gas-bearing and gas free parts of the same horizon. Besides,the sec-tion of envelope difference shows obvious amplitude anomaly along the periphery of gas reservoir. We can thus discover hydrocarbon accumulation by analysing the AVO characteristics of P-SV wave in an area.
AVO phenomenon of seismic reflection waves can be seen in both P wave andP-SV wave. Under some conditions,P-SV wave may show more obvious AVO phe-nomenon than P wave. AVO characteristics of P-SV waves from top and bottom of gas-bearing sandstone has been analysed with the use of Zoeppritz equation and re-lated petrophysical parameters. Having converted seismic data from x-t domain to θx domain by ray tracing method,we can see very obvious amplitude-variation differ-ence between gas-bearing and gas free parts of the same horizon. Besides,the sec-tion of envelope difference shows obvious amplitude anomaly along the periphery of gas reservoir. We can thus discover hydrocarbon accumulation by analysing the AVO characteristics of P-SV wave in an area.
引文
1Domenico S N主编.横波勘探论文集,石油工业出版社,1987
2周竹生.P-SV波和SH波的AVO分析.石油地球物理勘探,1993,28(4):430～438
3胡中平.AVO分析与转换波的叠加响应.石油地球物理勘探,1994,29(增刊1);20～23
2周竹生.P-SV波和SH波的AVO分析.石油地球物理勘探,1993,28(4):430～438
3胡中平.AVO分析与转换波的叠加响应.石油地球物理勘探,1994,29(增刊1);20～23
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