中国大陆科学钻探孔区的地震波速模型  

Seismic velocity model of the Chinese continental scientific drilling site

作　　者：杨文采[1] 杨午阳[1] 程振炎[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037

出　　处：《地球物理学报》2006年第2期477-489,共13页Chinese Journal of Geophysics

基　　金："九.五"国家重点科学工程项目"中国大陆科学钻探工程";国家重点基础研究发展计划(973)项目(2003CB716505)共同资助.

摘　　要：大陆钻探区地震资料的解释正确与否取决于对该区确定地震波速模型,地震波速模型的确定是反射地震处理极为困难的问题.中国大陆科学钻探提供了难得的深孔岩性、构造与地球物理测井资料,可以对结晶岩区地震资料时深转换的精度与地震波速模型的确定进行检验.本文介绍了科学钻探前根据地表资料建立波速模型的方法及钻探后由钻孔资料建立波速模型的方法.由地表资料建立的波速模型其精度分布是不均匀的,其波速反演的方差将随深度成正比地放大,在有钻孔时应尽量根据钻孔资料加以修正.由地球物理测井和岩芯的波速测试结果建立的波速模型结予波速估计值均匀的约束,说明由钻孔资料取得的波速模型可以有效地降低在深部的误差,提高地震反射与岩性变化和波阻抗合成的地震道之间的相关性.为检验波速模型,由测井资料与波速模型作出的合成地震道与反射地震剖面对比时还必须考虑到井孔的实际轨迹,否则对比相关性可能明显减小.Interpretation of seismic data is dependent on a correct velocity model in the survey area. Determination of the velocity models becomes the most difficult problems in data processes of reflection seismology. During the performance of the Chinese scientific drilling we obtain full cores and well-logging data, providing a good opportunity to build up a correct velocity model for time-depth transfer of the seismic data. This paper introduces first the methods of establishing velocity models based on surface rock measurements before the drilling, and then a method based on cores and well-logging data after the drilling. The accuracy of a velocity model based on surface measurements is not uniform as its variance increases with the depth. The situation can be improved by using drill-hole data. The core measurements and well-logging data give uniform constraints to accuracy of an estimated velocity model, reducing errors of the velocity estimates in deep parts, therefore increasing the fitness between the real seismic profiles and synthetic seismic traces. In order to test the velocity model with best fitness, one has to consider real variation of holes in comparison between the real and the synthetic seismic traces.

关 键 词：大陆科学钻探 反射地震 波速模型 时深转换 精度 

分 类 号：P315[天文地球—地震学]