三维地震资料时深转换中存在的问题及解决方法

Problems in the time-depth conversion of 3D seismic data and their solutions

以前三维地震资料时深转换中应用的分层统一速度成图法，在构造简单、地层厚度横向变化不大的地方，此方法计算的构造图精度较高；但在构造复杂、地层厚度横向变化较大的地方，则此法的成图误差较大。为此，本文采用了分层变速成图法作时深转换，推导了计算公式，从地表开始，用分层段计算每个地层厚度的办法来确定任一反射界面的深度，弥补了以往方法的不足。实际应用的结果表明，本文提供的方法精度较高，具有实用价值。

The stuctural maps obtained with a uniform velocity in time-depth conversion for 3D seismic data are of high accuracy for areas with little lateral change for formation thickness and are of low accuracy for structurally-complexed areas with great lateral change for formation thickness. This paper proposes to stratifiedly do time-depth conversion for each layor with ve locity being either uniform or variable. From the uppermost, the depth of each interface is determined via computation of the thickness of each layer. Computing formulae are derived in the paper. Results from the actual application show that the method is of high accuracy and practical value.