样品粒径对高过成熟度页岩低压气体吸附实验结果的影响

为了评价样品粒径对页岩孔径参数测定结果的影响，并探索适用于页岩孔径参数测定的粒径范围，以渝东南地区下寒武统牛蹄塘组3块不同TOC含量的页岩为研究对象，结合低压N₂/CO₂等温吸附实验及有机岩石学、激光拉曼光谱学、XRD测试等方法，讨论了样品破碎、筛分等前处理对高过成熟度页岩的矿物组成、比表面积及孔径分布等测定结果的影响。结果表明：研究区下寒武统牛蹄塘组页岩孔隙类型主要为有机质孔和黏土矿物粒间孔，有机质孔隙的发育具有非均一性；破碎筛分会对页岩的矿物组成产生无规律的分异作用；样品粒径小于0.425 mm（>40目）时，粒径降低会增大页岩的比表面积并显著影响介孔和宏孔的孔体积，但是当样品粒径大于2 mm（<10目）时，会显著增加低压N₂等温吸附实验的时间；粒径大小对微孔孔体积的影响不明显。综合实验结果的稳定性、时效性及页岩的非均质性等因素，建议采用10~40目的样品来开展页岩的孔径参数分析测试实验。

The effect of particle size on low pressure gas adsorption experiments for high-maturity shale

To evaluate the effect of particle size on the determination of shale physical parameters and explore the suitable particle size range for such analysis, three samples with different TOC content from the Lower Cambrian Niutitang Formation in southeast Chongqing area were investigated. Combined with low pressure N₂/CO₂ adsorption experiments, organic petrology, laser Raman spectroscopy and XRD mineralogical results, the influence of crushing and sieving on the measurement of mineral composition, specific surface area and pore size distribution were discussed. The results are as follows:(1) Pores within organic matter and intergranular of clay minerals are the main types in shale samples, and the development of organic pores are heterogeneous;(2) The procedure of sieving can cause irregular differentiation to mineral composition of shale samples;(3) The results of low pressure N₂ adsorption experiment indicate that when the particle size is less than 0.425 mm(>40 Mesh), smaller particle size can increase the specific surface area and obviously affect pore volume of mesopores and macropores; However, when the particle size is greater than 2 mm(<10 Mesh), further increase in particle size will significantly increase the experimental time; (4) Particle size has no distinct impact on the micropores in shales. Combining the experimental reliability and time efficiency as well as the heterogeneous nature of shale samples, particle sizes between 10-40 Mesh are recommended for the experimental analysis of shale physical parameters.