在过去的几年中,为了实现全三维的叠前深度偏移(PreSDM模块),提出了许多技术以更新所需要的速度深度模型。 这些技术(许多技术列在“进一步阅读的建议”中)受到一些具体的理论上或实践上的限制。而且,通常进行速度估计的地表信息的空间采样受到时间的限制。典型的叠前偏移的速度信息(通常以CRP的道集形式出现)输出在一个粗制的网格上,通常为500×500m。 In the past few years, many techniques have been proposed to update the required depth-depth models in order to achieve a full three-dimensional prestack depth migration (PreSDM module). These techniques, many of which are listed in the “Further Reading Suggestions,” are subject to some specific theoretical or practical limitations. Moreover, spatial sampling of surface information, which is usually used for velocity estimation, is time-limited. The typical velocity information for prestack migration (usually in the form of gathers of CRPs) is output on a coarse grid, typically 500 × 500 m.