中古8井区孔洞型碳酸盐岩储集层流体地震预测

Seismic Fluid Prediction in Caved Carbonate Reservoirs in Wellblock ZG8, Tarim Basin

针对塔里木盆地碳酸盐岩储集层孔隙类型复杂多变、非均质性极强的特点和现场难以预测储集层内部流体性质的现状,引入充分考虑了孔隙形状变化并通过微分方式避免速度频散的DEM-Gassmann岩石物理模型,对中古8井区井上碳酸盐岩储集层段进行流体置换,证明地层条件下该井区储集层内水的弹性属性与油气差别较大。通过弹性参数交会对比筛选了对流体性质识别最好的纵横波速度比与纵波阻抗和泊松比与纵波阻抗组合,根据AVO反演结果进行中古8井区鹰山组碳酸盐岩层段的流体预测,预测结果符合地质认识,与24口井资料吻合度为81.08%.理论分析和实例讨论为塔里木盆地碳酸盐岩储集层流体预测提供了切实可行的方案和相关标准。

Regarding the characteristics of complicated pore types and strong heterogeneity of carbonate reservoirs and based on the exploration status of fluid properties difficult to be predicted in Tarim basin,DEM-Gassmann rock-physics model which not only considers the influence of pore shapes on velocity but also diminishes velocity dispersion by differential method was employed for fluid substitution in the carbonate reservoirs in Wellblock ZG8,Tazhong area.It was concluded that the elastic properties of the water in the reservoir were different from those of oil and gas.Based on the comparison of elastic parameter crossplots,P-impedance vs.Vp/Vs and Poisson ratio vs.P-impedance were selected to identify fluid properties,and according to AVO inversion results,fluid property prediction was carried out for the carbonate reservoir in Yingshan formation of Wellblock ZG8.The predicted results were in accordance with the geological understanding obtained from 24 wells.Theoretical and case analysis in this paper provide some applicable methods and corresponding standards for the fluid prediction in the caved carbonate reservoirs in Tarim basin.