川东南地区龙马溪组页岩孔隙结构全孔径表征及其对含气性的控制

页岩气主要赋存于页岩孔隙中，研究页岩孔隙结构特征是深入认识页岩气富集机理的关键。通过CO2吸附、N2吸附、CH4等温吸附和高压压汞实验，对川东南地区龙马溪组页岩的孔隙结构进行了全孔径表征，并阐明了孔隙结构对页岩含气性的控制作用。页岩的微孔(＜2.0 nm)、中孔(2.0~50.0 nm)和宏孔(＞50.0 nm)都十分发育，且分布特征变化较大。在孔体积方面，中孔提供的孔体积最多，约40.8%，其次是微孔，约34.7%，宏孔的孔体积最少，只提供24.5%。在孔隙比表面积方面，微孔占有绝对优势，约提供76.87%，其次是中孔，约23.05%，宏孔只有0.07%。中孔和微孔提供了页岩中主要的孔体积，控制了游离气的含量。微孔的比表面积与CH4最大吸附量具有很好的正相关关系，且提供了页岩中主要的比表面积，控制了吸附气的含量。宏孔提供的孔体积和比表面积在页岩中不占优势，对吸附气和游离气含量的影响较弱，但可作为页岩气渗流的主要运移通道。因此，明确页岩的微孔、中孔和宏孔的分布特征，尤其是微孔对页岩中吸附气和游离气富集的贡献，对页岩气勘探与开发具有重要指导意义。

The whole-aperture pore structure characteristics and its effect on gas content of the Longmaxi Formation shale in the southeastern Sichuan basin

Since shale gas mainly occurs in shale pores, research on the pore structure characteristics is key to understand shale gas accumulation mechanism. Based on the experiments of CO2 adsorption, N2 adsorption, CH4 isothermal adsorption and high pressure mercury injection, the whole aperture pore structure of the Longmaxi Formation shale is characterized in the Southeastern Sichuan Basin and the controlling effects of pore structure on the gas content are explained. Micropores (<2.0 nm), mesopores (2.050.0 nm) and macropores (>50.0 nm) are developed in shale samples, and the distribution characters change obviously in each sample. In the aspect of pore volume, the mesopores have the biggest contribution to the whole pore volume, taking about 40.8%. It is followed by micropores, taking about 34.7%. The macropores have the minimum proportion in the whole pore volume, only taking 24.5%. In the aspect of surface area, the micropores have an absolute advantage in the whole surface area, accounting for about 76.87%. The second is mesopores, taking about 23.05%. The macropores only provide surface area of 0.07%. The main pore volume is provided by mesopores and micropores, which controls the content of free gas. The surface area of micropores has a good positive correlation with the largest CH4 adsorption contents, and makes up the main surface area in shale samples, which controls the content of adsorbed gas. The macropores are not dominant in pore volume and surface area, and its influence on the content of adsorbed gas and free gas is relatively weak. But the macropores can be the main channels for shale gas seepage. Therefore, understanding the distribution characteristics of micropores, mesopores and macropores, especially the contribution of micropores on the enrichment of adsorbed gas and free gas, has an important guiding significance to the shale gas exploration and development.