摘要
共聚焦点(CFP)偏移技术是一种基于等时原理,将Kirchhoff积分法的一步偏移分两步聚焦(即激发聚焦和检波聚焦)来完成的叠前地震成像方法。它通过时空域的零走时成像原理(共聚型CFP偏移)和拉冬域的零截距时间成像原理(双聚型CFP偏移)分别实现构造成像(角平均的标量成像)和岩性成像(考虑AVO的矢量成像)。
本文基于了波动理论来进行共聚型CFP偏移成像和进行CFP-AVP分析,在共聚型成像的过程中,应用了波场延拓理论来生成共聚焦点(CFP)道集,基于波动方程的傅立叶有限差分法进行了CFP偏移成像,并在论文中实现了CFP相对保幅成像,取得了良好的效果。结合基于射线理论的CFP偏移技术,利用差异时移分析,相位误差的对称性,实现了速度模型的扫描更新。基于共聚焦点技术进行的AVP分析是共聚焦点技术在地震属性分析领域的一大突破,论文中两步聚焦都是基于波动理论来实现的,在处理实际资料或者复杂理论模型时,对第二步聚焦结果实现了滤波处理,以提高反射率函数的质量,并最终应用双聚型CFP偏移方法得到了目标区域各聚焦点的AVP剖面。模型试算和实际数据试处理表明了CFP-AVP分析方法的有效性和实用性。
Common focus point migration technology is a kind of prestack seismic imaging method based on the principle of equal traveltime and it separates Kirchhoff integral into two focusing steps (focusing in emission and focusing in detection). If structural information is sought, confocal version of CFP migration is fulfilled by the zero traveltime imaging principle in time domain. And if lithological information is required, bifocal version of CFP migration is implemented by the zero intercept time imaging principle in Radon domain.
In the thesis, we based on the wave extrapolation theory realize the confocal version of CFP migration and do the CFP-AVP analysis, during the confocal version of CFP migration, we create the common focus point gather based on the wavefield continuation theory, and realize the CFP migration applying the Fourier finite difference method which is based on the wave equation, and also we carry out the relative amplitude-preserved processing in the thesis, and get the nice result. Combining the CFP migration based on the radial theory, we use the differential time shift analysis, symmetry property of phase errors to realize the updating of the velocity model. Using the CFP technology to do the Amplitude Versus P analysis is a big breakthrough in the seismic property analysis field, in the thesis we come true the two steps focus by using the wave continuation theory, we make use of the filter processing to the second focus step, and improve the quality of the reflectivity function, and at last using the bifocal version of CFP migration we get the AVP sections of the focus points of the target field. Tests on model and real data show the validity and the practicability of this CFP-AVP analysis method
引文
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