大面积变速绘制构造图中速度参数的求取方法

Methods for velocity parameters extraction in plotting velocityvaried large-area structural maps

中国地质大学, 武汉 430074

Department of Applicd Geophysics． China University of Geosciences, Wuhan 430074

本文讨论了地震勘探中提取平均速度的各种方法, 并对其精度作了估计。文中特别对如何利用速度谱资料求取平均速度的问题作了较为详尽的讨论。指出了使用迪克斯(Dix)公式求取速度参数精度低, 且计算工作量大。为克服其缺点, 在一个高成熟探区我们提出了用多项式拟合法制作速度量板, 直接由均方根速度求取平均速度的方法。此方法具有精度高, 计算工作量小等优点, 是地震勘探中研究速度的一种新思路、新方法。为了提供大面积变速成图中所需的各主要反射层(5个区)的平均速度与层速度资料, 文中也简介了如何综合各种速度信息及绘制速度平面图的一些具体做法。

This paper makes a review of various methods for average velocity extraction in seismic survey and an estimate of precisions for them.Much discussion has been made on how to obtain average velocities from velocity spectrum. It is concluded that velocity calculation using the Dix formula is of low accuracy and hoavy computation. To overcome this shortcoming, for highly-matured exploration areas, we proposed here an alternative method which constructs a velocity template using polynomial fitting and compute the average velocities directly from the root-mean-square velocities. This technique is of high accuracy and not of much computation and provides a new approach to the velocity study in seismic survey.Also, in order to provide the average and interval velocities of each prominent reflector (5reflectors) for velocity-varied large-area mapping, some pieces of practice in integrating various velocity information and plotting the velocity map are briefly discussed.