苏北盆地火成岩发育区复杂断块精确成像对策

摘要

Pre-stack depth migration is an effective imaging method for complex structure and velocity field zones .In order to verify precise imaging ability of Kirchhoff ’s pre-stack depth migration(KPSDM) and the reverse -time migra-tion( RTM) ,imaging tests were carried out based on the velocity model for complex fault block of igneous area in Subei ba -sin.Experimental results showed that under the condition of reliable high -frequency velocity field ,RTM has obvious ad-vantage in imaging of fault blocks ,otherwise ,KPSDM was a viable option .In order to verify above experimental results ,by selecting seismic data with higher signal to noise ratio ( SNR) ,a reliable high-frequency velocity field was established , and the imaging processing was carried out .The results showed that RTM has obvious advantage over KPSDM in the aspect of improving imaging results of fault blocks and target layer under igneous rock .Therefore ,imaging methods for fault blocks of igneous zone were selected by SNR of seismic data .If seismic data have high SNR ,a more accurate high frequency ve-locity field can be set up .Thus RTM can achieve precise imaging for target layer .If the seismic data have low SNR ,KPS-DM will become a good choice .%叠前深度偏移是解决构造及速度场双复杂区成像的有效方法，为了验证克希霍夫积分法叠前深度偏移及逆时偏移在苏北盆地火成岩发育区复杂断块的精确成像能力，进行了基于苏北盆火成岩区复杂断块模型的成像试验，结果显示：在提供可靠的高频近似速度场的情况下，逆时偏移优势明显，反之，则克希霍夫积分法叠前深度偏移是可行的选择。为验证实验结果，选取信噪比较高的实际数据建立可靠的高频速度场并进行成像处理，结果证实：逆时偏移在断块成像及火成岩下目的层成像方面，效果明显优于克希霍夫积分法叠前深度偏移。因此，苏北盆地火成岩区复杂断块精确成像的方法选择，应根据数据信噪比而定，信噪比高，可建立较准确的高频速度场，宜采用逆时偏移；信噪比低则采用克希霍夫叠前深度偏移。