碳酸盐岩储层孔隙结构因子及渗透率敏感性分析

孔隙结构是影响碳酸盐岩储层渗透率的重要因素之一。孔隙结构对地震响应特征的影响主要体现在岩石骨架模型中。从岩石骨架模型中推导出的剪切柔度因子能够表征孔隙结构且对渗透率有一定的敏感性。在岩石物理模型调研基础上,归纳总结了常用的几种模型,并从中推导出新的孔隙结构因子;然后对比了各孔隙结构因子对低孔低渗和高孔高渗碳酸盐岩渗透率的敏感性,优选出对渗透率更敏感的剪切Lee因子;最后进行了剪切Lee因子渗透率敏感机理分析。分析结果表明,剪切Lee因子对渗透率敏感性更高,因此在渗透率预测时考虑剪切Lee因子可以提高预测精度;同时剪切Lee因子与孔隙主尺度之间具有良好的线性关系,这为孔隙主尺度地震预测提供了一条途径。

Carbonate rocks have complex storage spaces and pore structures.Their velocity and permeability vary greatly even with the same porosity,owing to the influence of pore structures.As a factor describing pore structure,shear flexibility factor affects the division of pore structures in carbonate reservoirs and the prediction of reservoir permeability.Pore structure factors that are more sensitive to carbonate pore structure and reservoir permeability were identified.According to the concept of shear flexibility factor,five new pore structure factors were proposed from five rock skeleton models.The sensitivity of these factors to permeability was analyzed using carbonate core data.Finally,the reason for the sensitivity of shear Lee factor to permeability was analyzed.The results showed that shear Lee factor is more sensitive to permeability of carbonate reservoirs,and its ability to divide the carbonate rock pore structure is better than that of the shear flexibility factor; therefore,it can be used as a factor to better divide pore structure.Shear Lee factor represents rock consolidation.The stronger the rock consolidation and the higher the P-wave velocity,the smaller the pores and the lower the permeability.This study will improve the prediction accuracy of the physical properties of reservoir if pore structure factors are considered.

中国石油天然气集团有限公司科技项目(2021DJ3701)和中国石油天然气股份有限公司科技项目(kt2021-12-02)共同资助。