Physical Characteristics of Coal Reservoirs and CBM Favorable Area Prediction in the Huaibei Coalfield, Northern China.

To quantitatively characterize middle-high-ranked coal reservoirs, the physical characteristics of seven coal samples from the Huaibei Coalfield in northern China were investigated in detail based on experiments including proximate analysis, coal petrology, low-temperature nitrogen adsorption (LTNA), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and methane isothermal adsorption. The results show that coal maceral in the Huaibei Coalfield is dominated by vitrinite, with a large change in the maximum vitrinite reflectance ranging from 0.7 to 2.

Investigation on Adsorption Pore and Fractal Analyses of Low-Rank Coals in the Northern Qaidam Basin.

The northern Qaidam Basin has abundant coal and coalbed methane (CBM) resources, and quantitative evaluation of adsorption pore characteristics has great significance for optimum selection of CBM-favorable areas. Based on vitrinite reflectance, coal maceral, proximate analysis, low-temperature N adsorption, and methane isothermal adsorption experiments, the heterogeneities of adsorption pores (pore diameter <100 nm) were quantitatively characterized, and relationships between fractal dimensions and physical parameters of low-ranked coal reservoirs were revealed. The results show that the micropore volume percentage ranges between 33.

Correlating Coal Petrology and Methane Adsorption Parameters of High-Volatile Bituminous Coals with P-Wave Velocity.

The parameters of coal petrology and methane adsorption are significant to exploit coal and coalbed methane (CBM). Based on borehole core sampling, a new method using the P-wave velocity to predict coal maceral, coal face index, and Langmuir parameter of high-volatile bituminous coals was proposed. The results showed that the P-wave velocity correlated positively with coal skeletal density, apparent density, and ash yield with fitting coefficients ( ) of 0.

Coal Macrolithotype Distribution and Its Genetic Analyses in the Deep Jiaozuo Coalfield Using Geophysical Logging Data.

Coal macrolithotypes are closely correlated with coal macerals and pore-fracture structures, which greatly influence the changes in gas content and the coal structure. Traditional macrolithotype identification in coalbed methane (CBM) wells mostly depends on core drilling observation, which is expensive, time-consuming, and difficult for broken core extraction. Geophysical logging is a quick and effective method to address this issue.

Study on the Applicability of Reservoir Fractal Characterization in Middle-High Rank Coals with NMR: Implications for Pore-Fracture Structure Evolution within the Coalification Process.

In order to evaluate the applicability of the pore-fracture structure fractal characterizations in coal reservoirs and confirm the internal relationships between the porosity, permeability, coal metamorphic grade, and pore-fracture structure, the pore-fracture features of 21 middle-high rank coal samples from Anhe, Jiaozuo, and Huaibei coalfields in northern China were investigated using a low-field nuclear magnetic resonance (NMR). All the coal samples are characterized by low moisture content ( ), low and medium ash yield ( ), and high vitrinite (V) in coal maceral. The adsorption space fractal dimension ( ) is positively correlated with the Langmuir volume ( ) under the three-peak transverse relaxation time ( ) spectrum.