塔河地区膏盐层对盐下地层地震反射波特征的影响

Impact of gypsum layer on seismic reflection feature of subsalt layer in Tahe area.

本文以塔河地区过乡 1井地震剖面解释所获得的膏盐层的真实模型作为盐体地震地质模型 ,采用射线正演模拟及地震波在弹性分界面上的能量分配关系 ,分析了盐下反射界面上的地震波运动学和动力学特征及对盐下地层成像精度的影响。分析结果表明 ,地震波经过塔河地区膏盐层及边缘时的反射覆盖次数和反射能量没有发生明显突变 ;小于 2 0 0 m厚的膏盐层所产生的时间上拉值小于 4 .2 ms。由此可见 ,塔河地区的盐体对盐下地层的成像精度影响较小 ,换句话说 ,塔河盐下地震构造成像可信度高。本文的研究结果将有助于开展整个塔河地区复杂盐体的盐下

Taking the real model of gypsum layer obtained from the interpretation of seismic section crossing Xiang 1 well in Tahe area as a seismic-geologic model of salt body and using ray-tracing forward modeling and the relation of energy distribution of seismic wave in elastic interface,the paper analyzed the kinematical and dynamic feature of seismic wave in subsalt reflector and its impact on imaging precision of subsalt layer.The analytic results showed that the reflected folds and reflected energy do not abruptly change when seismic wave traveled through the gypsum layer and its margins of Tahe area;the produced upward time shift is less than 4.2 ms when the thickness of gypsum layer is less than 200m.In view of this,the impact of salt body on imaging precision of subsalt layer is minimum in Tahe area,in other words,the subsalt seismic structural image has high confidence level in Tahe area.The studied results in this paper are of benefit to study the subsalt AVO feature and seismic imaging of complicated salt bodies in Tahe area.