菲涅耳带与洞缝型油气藏地震波场

Fresnel Zone and seismic wave field in the fracture-vug reservoir.

碳酸盐岩洞缝型油气藏可以看作是由准均质介质中随机分布大小形状各异的低速体共同组成的复杂非均匀介质。应用随机介质模型及非均匀介质弹性波波动方程对洞缝型油气藏进行了系统的正演模拟。对模拟地震波场进行了分析和总结,得出①溶洞横向尺度的变化对振幅影响很大;②溶洞高度的变化对振幅影响较小;③宽度较小溶洞的振幅变化比宽度较大溶洞的振幅变化复杂;④利用振幅可以确定小溶洞宽度;⑤不同溶洞的振幅变化规律存在差别等结论。利用惠更斯原理和菲涅耳带的思想从理论上对这些结论进行了分析和解释,结果说明溶洞型油气藏的地震波场主要由那些非均匀分布、大小形态各异的低速体所产生的强弱不同的散射(绕射)波组成,因此,要解决溶洞型油气藏的问题必需加强以散射(绕射)波为基础的处理方法研究。

The fracture-vug reservoir in carbonate rock may be regarded as a kind of complicated inhomogeneous medium made up of various low-speed bodies,which are random and has different size and form.In order to the predict problem, random medium model and elastic wave equations in inhomogeneous medium are used to forward modeling seismic wave-field systematically. We can find out some interesting phenomena, summarize the change characteristic of the seismic wave-field and get some meaningful conclusions from the resulted seismic wave-field Also we can make proper illustration for these phenomena and conclusions by Huygens's principle and Fresnel Zone opinioa It is proved that the dealing methods based on the opinions of scattering (diffraction) must be strengthened to study the problem of the reservoir by cavern.