关键词: 页岩气, 孔隙结构, 纳米级孔隙, 表征方法

Abstract: Shale gas is the free, adsorbed and dissolved gas accumulated in dark shale beds. The nature of pores is a key factor to decide gas storing of shale gas reservoir. The structure of gas shales pores is complex, and the pore diameters are mainly in nano-scale. The methods used in conventional gas system study cannot explain high production of shale gas systems in USA. The characterization of nanopores in gas shales plays a key role in shale gas system evaluation. The studies of nanopores in gas shales are reviewed and compared with each other. There are three kinds of shale gas system characterization: (1) Image analysis is based on a stereological analysis, using various types of microscopes such as scanning electron microscopes (SEM), transmission electron microscopes (TEM), scanning tunneling microscope (STM) and atomic force microscopes (AFM); (2) Intrusive methods are based on gas adsorption, mercury porosimetry, and calorimetric methods; (3) Nonintrusive methods are based on radiation scattering, wave propagation, positron lifetime spectroscopy, etc. Image analysis can obtain the morphologic information directly, rapidly and conveniently. Intrusive methods have advantages in characterization of fractal features of pore system. Because of in-situ, non- invasive analysis and high penetrability of neutron and X-ray, nonintrusive methods can simulate the pore system evolution under multi-geological settings. As each method has its own advantages, multi-scale detection using multi-technology is recommended in shale gas pore system characterization.

Key words: shale gas, pore structure, nanopore, characterization