基于全直径岩心CT扫描技术的三元复合驱后微观孔隙结构特征

采用CT扫描技术对5块全直径天然岩心进行微观孔隙结构定量化研究,直观展示了不同类型砂体不同物性特征的岩石三维微观孔隙结构参数,结合驱替实验开展"双胞胎"岩样水驱、三元复合驱微观孔隙结构参数变化规律研究。结果表明:全直径岩心CT扫描是研究微观孔隙结构的有效手段,岩心扫描切片可以有效地反映砂体内部的层理及孔隙分布特征;随着孔隙度降低,岩心孔隙直径和喉道直径依次减小,孔喉比依次增大,配位数依次减小;水驱和三元复合驱对储层孔隙结构变化均具有积极影响,随驱替倍数的增加,孔喉半径、配位数与面孔率增加,孔喉比降低,后续水驱阶段的三元复合驱岩样微观孔隙结构更为复杂;相同驱替倍数条件下,聚合物驱对储层结构的改变程度明显高于水驱。

Microscopic pore structure characteristics after ASP flooding based on CT scanning technique of the full-diameter core

Quantitative study was conducted for the microscopic pore structure of 5 natural cores with all diameter by means of CT scanning technique, the three-dimension microscopic pore structure parameters of the rocks with different physical properties of different types of the sandbodies were visually demonstrated, the study on the variation law of the microscopic pore-structure parameters was engaged for the water flooding and ASP flooding of the “twin” rock sample combined with the displacing experiment. The results show that the full-diameter core CT scanning is an effective way to study the microscopic pore structure, the core scanning slices can effectively reflect the bedding and pore distribution characteristics in the sandbodies;with the porosity decreases, the pore diameter and throat diameter decrease as well one by one, while the pore throat ratio increases one by one, the number of the coordination decreases;the water flooding and ASP flooding have positive influences on the pore structure change of the reservoir, with the increase of the displaced multiplier i.e. PV, the hole throat radius, coordination number and surface porosity increase as well, while the pore throat ratio decreases, the micro-pore structure of the ASP flooded rock sample at the subsequent water-flooding stage is more complex;under the same displaced multiple condition, the modified degree to the reservoir structure for the polymer flooding is significantly higher than that for the water flooding.