鄂尔多斯盆地致密气储集层孔隙流体地震预测方法

摘要

基于鄂尔多斯盆地上古生界二叠系下石盒子组盒8段致密储集层岩石物理分析结果,考虑体积模量对孔隙流体敏感的特点,提出了致密储集层岩相控制下利用压缩系数检测流体性质的方法.该方法首先是进行岩相识别,利用叠前反演的纵横波交会技术计算致密砂岩相的分布;其次是在岩相控制下(排除泥质含量影响),利用可稳定反演的波阻抗和速度计算压缩系数;最后利用气水层压缩系数的差异进行储集层孔隙流体性质判识.苏里格致密气田勘探开发生产实践表明:应用压缩系数进行孔隙流体性质识别的效果较好,能有效预测气水层的分布.%Based on the rock physical analysis of tight gas reservoirs in He8 Member of Permian Lower Shihezi Formation of Ordos Basin,and considering that bulk modulus is sensitive to pore fluid,this study proposes a fluid property detection method by compression coefficient of tight sandstone reservoirs under the constraint of reservoir lithofacies.In this method,lithofacies is identified first by calculating distribution of tight sandstone facies with the cross plot of Vp and Vs obtained from pre-stack seismic inversion;secondly,the compression coefficient is calculated by P-wave impendance and velocity from stable pre-stack seismic inversion with the restriction of lithofacies (excluding the influence of clay content);and finally,pore fluid properties are determined using the differences of compression coefficients in gas and water layers.Its application in tight gas exploration and development in Sulige gas field of Ordos Basin shows that this pore fluid prediction method by calculating compression coefficient can effectively and efficiently delineate the distribution of gas-bearing and water-bearing sandstone.