散射波叠前时间偏移成像

Scattered wave pre-stack time migration

砂体、尖灭、缝洞和小断层等非均质地质体是石油地震勘探非常重要的目标。由于受地震资料信噪比和分辨率的限制,常规的叠前时间偏移一般不易识别这类小尺度的非均匀地质体。而非均匀地质体散射波异常发育,因此利用散射波识别非均匀地质体具有重要的意义。本文提出了一种散射波叠前时间偏移成像方法,利用反射波和散射波的走时差异提取散射波并进行成像,从而识别非均匀地质体。数值试验和实际资料结果表明,该方法能够有效识别小尺度非均匀地质体,可为后续的地震资料解释提供基础数据。

Identification of small-scale non-uniform geological structures such as small faults,pinchouts,cracks and caves etc.is one of important goals of oil & gas exploration.However,such small-scale non-uniform geological structures cannot be imaged clearly based on traditional PSTM because of the limitations of resolution and/or signal-noise-ratio.It is a great signature to describe non-uniform geological structures with the advantage of scattered wave.When reflected wave was attenuated and scattered wave was preserved during seismic imaging,this kind of geological structures will be highlighted and can be easier to be identified.In this paper we present a scattered wave PSTM method,by which scattered wave is extracted and imaged via the travel time difference of reflected wave and scattered wave.Numerical experiments and real data processing show that this method can identify small-scale non-uniform geological structures and provide useful data for subsequent seismic data interpretation.