含气地层弹性性质及其波场响应

Elastic properties of gas-bearing strata and seismic response

王尚旭

Wang Shangxu

根据储层条件下天然气及地层水弹性参数变化特征的分析,通过含气地层纵、横波速度的计算,采用物理模拟与实验分析,含气地层具有以下波场响应特征:同一地层条件下相对比重较大的天然气比相对比重轻的天然气具有更高的纵波速度;含盐水岩石的纵波速度随盐水矿化度的增高而增大;流体性质不同对纵波速度影响较大,而对横波速度影响很小。地层所含流体不同其波场响应具有一定的差异,含气地层具有较强的反射能量,含水地层反射能量相对减弱;非均质性含气地层其波场响应中绕射波比较发育。

Based on analysis of variation of elastic properties of natural gas and formation water under reservoir conditions,calculation of compressional velocity and shear velocity through gas-bearing strata,and physical si-mulation and experimental analysis,it is believed that gas-bearing strata are characterized by the following seismic responses: compresional velocity of gas with larger specific gravity is higher than that of gas with smaller specific gravity;compresional velocity in rocks containing saline water increases with increasing water salinity;and fluid properties have relatively large influence on compressional velocity,but have little influence on shear velocity.There would be a certain different seismic responses in strata bearing different fluids.Reflected energy in gas-bearing strata is relatively strong,while that in water-bearing strata is relatively weak.Seismic response in he-terogeneous gas-bearing strata would be characterized by relatively well developed diffracted wave.

10.11743/ogg20050605