界面张力与润湿角校正对高压压汞法计算泥页岩孔径分布的影响——以松辽盆地青山口组为例

泥页岩储层孔隙结构研究对于页岩油气勘探、开发工作具有重要意义。高压压汞实验法是目前研究页岩孔隙结构、孔径分布广泛使用的方法。有学者对汞在石墨烯材料中润湿性研究发现，液态汞在孔隙中的界面张力γ和润湿角θ是孔半径r的函数，根据这一认识将Washburn方程中的界面张力γ和润湿角θ视为定值的传统数据处理方法表现出明显的不合理性，因此需要对Washburn方程进行参数校正。以松辽盆地青山口组页岩样品为例，进行高压压汞实验，利用校正前后的Washburn方程处理压汞数据，结果发现参数校正后得到的微孔(<2 nm)体积占比，比校正前微孔体积占比增加了118%，中孔(2~50 nm)体积占比减小了7%，大孔(>50 nm)体积占比基本不变，参数校正后得到的孔径分布能更加精确地表征页岩的孔径分布。

Influence of Correction of Interfacial Tension and Wetting Angle to the Pore Size Distribution of Shale by Means of High Pressure Mercury Porosity:A Case Study of Qingshankou Formation in Songliao Basin

It is very important to study the pore structure of shale reservoirs for the exploration and development of shale oil and gas. The high pressure mercury intrusion method is widely used in the study of shale pore structure and pore size distribution. Some scholars have studied the wettability of mercury in graphene materials. It has been found that the interfacial tension γ and wetting angle θ of liquid mercury in the pores are a function of pore radius r. According to this understanding, the traditional data processing method, which regards the interfacial tension γ and wetting angle θ as determinants in the Washburn equation, shows obvious irrationality. So it is necessary to correct the parameters of Washburn equation. In this paper, the high pressure mercury intrusion test was carried out in the Qingshankou Formation of the Songliao Basin. The data of the mercury intrusion corrected by the Washburn equation before and after the correction were analyzed. It was found that the volume fraction of the micropores (<2 nm) obtained after the calibration was increased by 118%, mesoporous (2 to 50 nm) volume proportion decreased by 7%, macroporous (>50 nm) volume ratio of the basic unchanged. The pore size distributions of the shales can be more accurately characterized by the pore size distributions obtained after the calibration.