Investigation on the CBM Extraction Techniques in the Broken-Soft and Low-Permeability Coal Seams in Zhaozhuang Coalmine

Table 1

Coal structure characteristics and description of Zhaozhuang coalmine.

Stratum	Thickness/m	Macrolithotype	Structure	Description
1	0.40~0.50	Semidark	Mylonitic	Mylonite, semidark coal, mainly in the form of scales, hand twist into powder, local visible
2	2.60-3.80	Semibright	Cataclastic	Mainly cataclastic coal, with thin layer of crushed coal, horizontal bedding, dip angle of 2°~3°, fissure development, fissure cut through bedding oblique crossing, a few centimeters to dozens of centimeters in length, fissure dip angle of 40° and 120°, obviously wrinkled mirror face
3	0.20~0.40	Semidark	Fragmented	Mainly fragmented coal, hand twist into granules
4	0.30~1.20	Semidark	Mylonitic	Mylonite coal, mainly in the form of scales, hand twisted into powder. At the top of the layer, there is a thin layer of carbonaceous mudstone gangue, which can be seen locally.