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

作者：Li T.-F.; Tian H.^*; Xiao X.-M.; Cheng P.; Wang X.; Wu Y.-W.; Wu Z.-J.

来源：天然气地球科学, 2020, 31(9): 1271-1284.

DOI：10.11764/j.issn.1672-1926.2020.04.021

• Low pressure N2 and CO2 adsorption
• Mineral composition
• Particle size
• Shale gas

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.

• 单位
  中国科学院大学