珠江口盆地碳酸盐岩下构造深度校正探讨

Seismic data depth correction of strata beneath the carbonate in the Pearl River Mouth Basin

地震资料显示,高速层的存在会对下部地层产生上拉现象,影响下部地层成像的准确性,甚至产生构造假象,给油气勘探带来预测难点。文章尝试从理论模型出发,通过研究产生上拉的影响因素,建立上拉系数量版法,定量分析上拉幅度,进而还原下部地层构造。研究表明:上拉幅度受控于高速体速度、厚度和围岩速度,交会量版说明上拉系数与高速体速度基本呈线性关系。在此基础上建立相应地质模型,并进行实例解剖,表明了此种方法对局部构造深度预测是有效的。

A pull-up seismic reflection imaging artifact is caused by the overlying high velocity layer,making the interpretation of the underlying strata inaccurate.This inaccuracy would make the oil&gas exploration difficult.A quantitative template of pull-up coefficient was set up based on the analysis of controlling factors and theoretical models.The structure underlying the high velocity layer can be restored by quantitative analysis of the amplitude of pull-up effect.The results show that the extent of pull-up was controlled by the rate and thickness of high velocity layer,and by the velocity of surrounding rocks.Moreover,the pull-up parameter had a linear relationship with the velocity of carbonate in template.On this basis,the geologic models were made,and the structure was analyzed in a test.It was indicated that this method could be more effective in imaging the structure.