摘要
岩石中的孔隙和裂隙可用椭球状孔隙模拟,用椭球的长短轴之比定量描述这类孔隙的纵横比。笔者利用Berryman散射模型方法,得到孔隙度、流体饱和度、孔隙纵横比与泊松比、速度、密度的关系,通过一个砂泥岩界面的理论模型的AVO正演模拟,探讨孔隙纵横比对AVO的影响,模拟结果表明对具有相同矿物成份和孔隙度的岩石,由于椭球状孔隙的纵横比不同,导致反射系数(振幅)随入射角的变化也不同。随着孔隙纵横比的增大,AVO交会图对气层的识别能力逐渐降低,孔隙纵横比越小,对AVO交会图识别气层越有利。
Pores and fractures in rocks described with the aspect ratio as their shapes can be simulated by ellipsoids. The Berryman dispersion method was used in this paper, with which the Poisson＇s ratio, velocity and density of porous rocks are related to the porosity, fluid saturation and pore aspect ratio. The effect of aspect ratio on AVO response was also studied by a shale/sand modeling. The results show that the reflectivity or amplitude versus incidence varies with the aspect ratio change under the condition of the same mineral component and porosity, and the distinguishability of gas in AVO cross-plot decreases with the increasing aspect ratio. The smaller the aspect ratio, the easier the gas layer recognition by cross-plot.
出处
《物探与化探》
CAS
CSCD
2008年第1期53-56,共4页
Geophysical and Geochemical Exploration
