复杂地表复杂地下地区地震成像技术研究

A Study on seismic imaging techniques in complex surface and subsurface areas

杨勤勇 方伍宝

Yang Qinyong Fang Wubao

针对我国南方复杂地表和复杂地下地区的地震勘探难点,开展了偏移成像技术研究。首先对偏移算法进行了论述,推导出叠前时间偏移中的旅行时计算方法和加权因子计算方法,提出了非对称旅行时计算思想,使起伏地表直接Kirchhoff叠前时间偏移技术能够适应速度的较强横向变化;然后讨论了全速度模型建立技术(浅中深层速度融合技术),给出了起伏地表条件下综合建立速度模型的实现流程;最后给出了起伏地表叠前深度偏移的Fourier有限差分延拓算子,实现了起伏地表的叠前深度偏移。利用合成地震数据和实际数据验证了方法的有效性和实用性。

Aiming at seismic survey difficulties in complex surface and subsurface areas of South China,seismic migration and imaging techniques are studied.First,migration algorithms are discussed and the methods to calculate travel-time and weighting factor are derived for pre-stack time migration,presenting an idea of calculating asymmetrical travel-time,which can allow Kirchhoff pre-stack time migration directly from rugged topography to match higher lateral changes of velocity.Second,a technique to build an overall velocity model(a technique to integrate shallow,middle and deep velocity into a model)is discussed,resulting in a workflow to build a comprehensive velocity model under a condition of rugged topography.Finally,the continuation operator of Fourier finite difference has been developed for the pre-stack depth migration directly from rugged topography.All the proposed methods have been verified with synthetic and real seismic data.

10.11743/ogg20080517