基于孔隙矿物和流体分布的致密油储层润湿性研究

基于孔隙周围矿物分布和不同大小孔隙内流体分布特征研究致密油储层岩石整体及不同大小孔隙的润湿性。首先基于扫描电镜实验研究了致密油储层中不同尺寸孔喉周围的矿物分布特征，其次借助自发渗吸和核磁共振实验研究了不同流体进入致密油储层孔隙后的分布状态，最后基于孔隙周围的矿物分布特征，通过岩石分别在水相和油相中自吸后的自吸曲线和核磁T₂谱分布判断岩石整体及孔喉润湿性。研究结果表明，目标岩心大孔隙周围以碳酸盐岩矿物为主，小孔隙周围以黏土矿物和硅酸盐矿物为主；自发渗吸和核磁实验相互验证显示岩石整体偏水湿，具体为大孔隙偏油湿，小孔隙偏水湿。该研究为评价致密油岩石整体及不同大小孔隙的润湿性提供了新思路。

Study on the wettability of tight oil reservoir based on pore mineral and fluid distribution

The overall wettability of tight oil reservoir rock and the wettability of its different sizes of pores were studied based on the mineral distribution around pores and the fluid distribution characteristics in different sizes of pores. Firstly, the mineral distribution characteristics around different sizes of pore throats in tight oil reservoirs were researched on the basis of scanning electron microscope (SEM) experiment. Then, the distribution states of fluid after flowing into the pores of tight oil reservoirs were investigated by means of spontaneous imbibition and nuclear magnetic resonance (NMR) experiment. Finally, based on the mineral distribution characteristics around pores, overall rock wettability and pore throat wettability were analyzed by using the imbibition curve and NMR T₂ spectrum distribution after the imbibition of the rock in water phase and oil phase respectively. It is indicated that around the large pores in the target core are mainly carbonate minerals and around the small pores are mainly clay minerals and silicate minerals. What’s more, spontaneous imbibition and NMR experiment verify each other, indicating that the rock is overall prone to water wettability, specifically water wettability prone in large pores and water wettability prone in small pores. This research provides a new idea for evaluating the overall wettability of tight oil reservoir rocks and the wettability of their different sizes of pores.