Analysis of the role of seismic velocity in depth prediction

Summary Depth prediction is one of the most important and widely discussed problem in geophysical research, and how to improve the depth prediction accuracy using seismic velocity is always concerned in reservoir geophysics. In the condition of horizontal layered medium, this paper firstly deduced the accuracy limit for RMS velocity based on the NMO theory, then compared the accuracy limits of RMS velocity and average velocity, which is related to depth prediction directly, the results showed they are almost the same, their relative errors is about 0.5%-1% in shallow layers and will be rapidly amplified with depth. The depth prediction error, caused by the velocity error, can't meet the accuracy requirement in the middle and late stages of oilfield development. So this paper holds that the seismic velocity couldn't improve the accuracy of depth prediction further, but can be used to control the structural trend because of its lateral stability, especially in non-well areas.