Kirchhoff prestack time migration of crooked-line seismic data

Abstract

Crooked-line seismic survey has been widely used in oil and gas exploration in complex areas of western China. However, due to the unconventional acquisition geometry, current migration methods cannot fully account for the characteristics of crooked-line seismic data and may lead to poorly-resolved images with inaccurate kinematics. To mitigate this problem, we present in this paper a modified Kirchhoff prestack time migration well adapted to crooked-line seismic data. We first carry out a theoretical analysis on the propagation geometry of crooked-line seismic data and demonstrate problems associated with conventional 3D traveltime-based migration. Then, we present a modified 2D migration scheme based on the projection between the actual imaging trace within the vertical plane of seismic reflections and the output imaging trace. Compared with the 3D traveltime-based migration, our method not only ensures the accuracy of imaging depth but also improves the focusing and continuity of the migrated image. We use both synthetic and real data tests to validate the correctness and effectiveness of the proposed method.