关于井间地震层析成像中几个问题的探讨

Approach to some problems in crosshole seismic tomography

基于射线理论的井间地震速度层析成像技术已在石油开发和浅层工程勘探领域得到了初步应用，并显示出良好的解决复杂地质问题的能力。本文就目前常用的直达透射液旅行时速度分析成像的应用情况，提出几个容易忽视的问题（直达透射液旅行时的确定、大倾角地层层析的不确定性、射线分布不均匀的影响）并进行讨论。文中展示了这些问题的现象，并设计了井间模型进行正演计算，从理论上定量或定性地分析其形成机制，提出相应的改正方法和对策，旨在提高层析成像的效果。

Crosshole seismic velocity tomography based on seismic ray theory has seen itspreliminary application in oil development and shallow engineering exploration,andexhibits its good ability to cope with complicated geologic problems- Some easy ne-glected problems in the velocity tomography using travel times of direct transmittedwave are discussed,which involve the travel time determination of direct transmit-ted wave,the indefiniteness of steep-formation tomography,and the influence due tothe nonuniformity of seismic rays. The article also describes how we distinguish thephenomena of these problems, design crosshole model for forward computation,analyse their generation mechanisms quantitatively and qualitatively,and take somesatisfactory measures for coping with them so as to improve the effect of tomogra-phy.