Study on micro-pore characteristics of structural coal in different coal bodies under scanning electron microscopy

Coal structure is one of the key factors affecting coal pore development characteristics and coalbed methane occurrence and migration behavior. In order to explore the micro-pore development characteristics of coal with different degrees of damage, a large number of observations on micro-pores of four different coal structure types, such as primary structural coal, broken coal, broken coal and glutinous coal, from Zhaozhuang Coal Mine were carried out by using scanning electron microscopy. Based on the observation data of scanning electron microscopy, the genetic types of coal micro-pores were divided, and the pore morphology, pore connectivity, pore size and filling conditions were systematically studied. This study found that there were four types of primary pores, metamorphic pores, mineral pores and exogenous pores in No.3 coal seam of Zhaozhuang Coal Mine, and seven types of micro-pores with different genetic types, such as cellular pores, stomata, mold holes, dissolution holes, friction holes, brecciate holes and broken grains. The genetic types and developmental degrees of micro-pore in different coal-structured coals are different. The primary pores, metamorphic pores and mineral pores are mainly developed in original structure coal and fractured coal with relatively intact structure and structural preservation. Coal pore stability Better and relatively regular pore morphology. Exogenous pores are mostly developed in fragmented coal and xylonite coal with serious coal structure damage, and the pore stability of coal is poor and the pore morphology is irregular. Coal pore connectivity is generally low and filled with debris. The pore size varies widely from a few thousand nanometers to several tens of micrometers.