关键词: 三维地震勘探, 三维弯曲界面, P波反射时距, 界面反射点

Abstract: It's very difficult and time-consuming to calculate the precise location of the reflection points in the reflection time-distance simulation of 3D complex tectonic model. In order to analyze the P-wave reflection time-distance characteristic systematically and accurately,the paper regards 3D curved interface as the envelope of 3D dipping interface with different tendencies and inclinations,and presents a new method for calculating P-wave reflection time-distance from 3D curved interface,using the principle of reflection from 3D dipping interface. Based on the dip layer CDP theory,the location of shot points and reflection travel times are obtained from the positions of receivers and surface CDPs,finally the 3D P-wave reflection records of shot gather are received,assuming that the distribution of interface reflection points is known. Numerical simulation results of shot gather show that this method has high computing efficiency and can be applied to analysis of the P-wave reflection time-distance characteristic with different positions of shots; especially it can reveal the relation between reflection points and time-distance curve. The reflection time-distance feature comparison of 3D curved interface and 3D dipping interface shows that it's very hard to distinguish time-distance characters between two types of interfaces only from the same survey line orientation,and this problem can be solved by comparing time-distance differences from different survey orientations.

Key words: 3D seismic exploration, 3D curved interface, P wave reflection time-distance, reflection points