Pore Characteristics of Coal Reservoir in Jixi Basin

摘要

The pore structure is the core problem in the study of unconventional reservoirs such as coalbed methane(CBM),which not only controls the reservoir capacity but also affects the development evaluation.Taking coal in Jixi Basin as the research object,quantitative analysis of pore and fracture structure by low temperature nitrogen adsorption method,argon ion polishing scanning electron microscope and nuclear magnetic resonance(NMR),combined with energy spectrum analysis,whole rock analysis,coal components.Based on the experimental data,the main controlling factors of pore development in the Jixi Basin are discussed.The results show that the organic pores in the Jixi Basin are mainly gas pores,and the main pores are bottle-shaped pores.The mineral pores are mainly intercrystalline pores of clay minerals.The pores are cylindrical pores with open ends and parallel plate-shaped pores with openings on both sides.The low temperature nitrogen adsorption curves of coal all develop hysteresis loops,which have strong adsorption capacity and difficult desorption.The NMR spectrum shows two types of bimodal and trimodal distribution,the latter showing fracture development well,which is conducive to CBM migration.The degree of stomatal development is mainly controlled by the degree of evolution,and the mineral pores are closely related to the clay mineral content.