井间地震层析成像中自动生成初始速度模型的方法研究

Automatically building the initial velocity model in the seismic crosshole tomography

1. 中国科学院地质与地球物理研究所,北京 100101;2. 中国石化石油勘探开发研究院南京石油物探研究所,江苏南京 210014

Geology and Geophysics Institute of Chinese Academy, Beijing 100101, China

初始速度模型对走时层析成像的质量和收敛速度影响很大,但对初始速度如何选择这一问题的探讨不多。经初步研究,提出了一种自动求取层析成像初始速度模型的方法。该方法假定激发点到接收点间的射线是直射线,并利用从地震记录上拾取的初至走时来求取初始速度模型。初始速度模型的建立由程序自动实现,无需人工干预。最后,用数值模拟和物理模型进行了验算,将获得的初始速度模型用于同时迭代重建技术(SIRT)层析成像处理,处理结果与真实速度模型基本对应。

Aim to the initial velocity chose, this method is supposed that the ray from shot to receiver is straight, and the observed traveltimes picked from the seismic sections, the initial velocity model used in the seismic tomography can be calculated. The advantage is not depended on the log data, based on the observed traveltimes completely. The Simultaneous Iterative Reconstruction Technique is utilizes the ray-bending tracing operator based on the Shorted Path Tree. This method is practical by the tomographic results of numeric and physical models. Meanwhile, it is simple and complemented easily, improve the efficacy and stability of tomography algorithm.