井间地震反射波有限角度叠加方法研究与应用

The study and application of cross-hole seismic feflection finite angle stacked method

在井间地震资料采集中,为了使地震波能够传播较远的距离,可控震源能量辐射主要集中在水平方向,这就导致井间地震反射波主要是大角度入射角的地震波,其中含有超过临界角的非正常反射。为了消除这些广角反射对上行反射波成像结果的影响,我们利用CDPMAP方法对上行反射波进行Z—T域到Z—X域的映射,在CDP道集内按照入射角度进行抽取,形成了CDP角度道集;采用声波测井速度进行入射角度道集的合成记录制作,确定临界角范围,实现了正常入射角度范围内的叠加成像。

In order to make seismic wave propagate in longer distance, the energy radiation pattern is focused on the horizontal direction. This result in which there are many seismic waves whose incidence angle is very big in crosswell reflected wave field. It includes both wide-angle reflection which have bigger incidence angle than critical angle and normal-angle reflection. To avoid side effect of these stacked reflection, this paper studied the CDP MAP method based on Vertical Seismic Profiling. It can transform the data from Z-T domain to Z-X domain. So we can create the CDP gather sorted by their incidence angle. Using sonic logging data to get synthetical angle gather, then the range of the critical angle can be decided. So we stack all the data which have normal incidence angle and carry out crosswell imaging.