Characteristics of coal fractures and the influence of coal facies on coalbed methane productivity in the South Yanchuan Block, China

Evaluation of deep high-rank coal seam gas content and favorable area division based on GIS: A case study of the South Yanchuan block in Ordos Basin

“…However, for the complex geological structure area, the influencing factors of gas content are multitudinous and the mechanism of action is elusive. Especially for the South Yanchuan block, the discussions of the geological controls on the gas content are limited and the evaluation of CBM resources in this field is insufficient, which leads to the lack of theoretical basis of CBM development in this block (Li et al, 2015a(Li et al, , 2015bTang et al, 2018). To promote the CBM development in this area, the thorough understandings of the CBM accumulation rule and its geological control mechanism are needed, the reasonable evaluation of CBM resources in the south Yanchuan Block is necessary.…”

“…Fu et al (2016) analyzed the importance of influencing factors on CBM content and carved out the grade of the exploration potential of Xishanyao coal (the middle of the southern Junggar Basin, North China) by the analytical hierarchy fuzzy prediction method and optimal segmentation method. Li et al (2015aLi et al ( , 2015b compared the geological setting of five CBM blocks in western Guizhou and eastern Yunnan and proposed the optimized method using coal reservoir physical properties to evaluate the CBM potential by using the multiobjective and multi-level fuzzy optimization model, founding that the Zhina area is the most favorable zone for CBM production. Apparently, the multi-level fuzzy evaluation model integrates the advantages of AHP, geographic information system (GIS) and fuzzy mathematic model, which can be used to convert the different influencing factors into quantitative parameters for the CBM comprehensive evaluation.…”

Characterization and estimation of gas-bearing properties of Devonian coals using well log data from five Illizi Basin wells (Algeria)

“…CBM can be effectively produced from sub-surface coal resources by reducing their pressure by pumping out the water from the cleat systems (Bodden and Erlich, 1998;Li et al, 2015). Typically, the water-saturated cleat systems of CBM formations need to have substantial quantities of water removed, and the depressurization phase takes substantial time, perhaps a year or more for each well bore (McLennan et al, 1995;Li et al, 2018).…”

Anisotropic Adsorption Swelling and Permeability Characteristics with Injecting CO2 in Coal

“…Besides, the difference of pore shape and fracture length, width, roughness, and orientation in the coal skeleton are deemed to be structural inhomogeneity . Especially, diverse pores in coal are divided into open pores, semiopen pores, and closed pores according to pore connectivity. − The fracture network structure generally presented in coal beds mainly includes exogenous fractures and cleats (face cleat and butt cleat); , the former are induced by multistage tectonic movements during coal-forming geological periods, and the latter result from the pyrolysis-induced matrix shrinkage and in situ stress fields . Cleats, acting as the link bridges between adsorption pores and macrofractures, control the seepage pivots of CH 4 output or CO 2 injecting.…”