Optimization methods of production layer combination for coalbed methane development in multi-coal seams

Yang, Zhaobiao; Zhang, Zhengguang; Qin, Yong; Wu, Congcong; Yi, Tongsheng; Li, Yangyang; Tang, Jun; Chen, Jie

doi:10.1016/s1876-3804(18)30034-x

Cited by 79 publications

(18 citation statements)

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“… 43 Overall, the geological characteristics of eastern Yunnan and western Guizhou include abundant CBM resources, multiple and thin coal seams, high stress, and large variation of coal rank. 8 , 9 , 44 , 45 …”

Section: Geological Backgroundmentioning

confidence: 99%

Pore Structure Characteristics of Coal and Their Geological Controlling Factors in Eastern Yunnan and Western Guizhou, China

Qin

You

et al. 2020

ACS Omega

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Coalbed is the carrier for coalbed methane (CBM) enrichment and migration. The pore structure characteristics of coal and their main geological controlling factors are critical to the exploration and development of CBM. In this paper, 20 coal samples were collected from eastern Yunnan and western Guizhou, China. Based on vitrinite reflectance, proximate analysis, maceral analysis, and low-temperature N 2 adsorption/desorption (LT-N 2 GA) experiments, the hysteresis coefficient of low-temperature N 2 desorption was proposed, the types of pore structure were identified, and the effects of coal facies and rank on the pore structure were revealed. The results show that the R o,max values of the 20 coal samples are between 0.74 and 3.38%, which belong to medium- and high-rank coal. In the coal macerals, the vitrinite is mainly collodetrinite. The inertinite is dominated by semifusinite, and some coal samples contain exinite. The coal samples investigated can be divided into two types. Type A samples mainly contain open pores, while type B samples are rich in bottle-shaped pores. Compared with type A coal samples, type B samples have the characteristics of smaller total pore volume (TPV), smaller average pore diameter (APD), larger specific surface area (SSA), and larger hysteresis coefficient. The coal samples are located in three regions of different coal facies, including low-level swamp (reed) facies, wetland herbaceous swamp facies, and wet forest swamp facies. The tissue preservation index (TPI) values of most coal samples are less than unity, which indicates that herbaceous plants have absolute dominance in the coal-forming plants in eastern Yunnan and western Guizhou. The maximum vitrinite reflectance ( R o,max ), gelification index (GI), TPI, vitrinite content ( V ), inertinite content ( I ), Barrett-Joyner-Halenda pore volume ( V BJH ), Brunauer–Emmett–Teller SSA ( S BET ), and low-temperature N 2 desorption total hysteresis coefficient ( H t ) were clustered using the R-type cluster analysis method. It is found that TPI is the main controlling factor of the pore structure of type A coal samples, while the pore structure of type B coal samples are jointly controlled by TPI and coal rank. Type B coal samples are mainly located in Zhuzang and Laochang high-rank coal research areas, while the distribution of type A coal samples is mainly in other medium–high-rank coal research areas. These results will contribute to the exploration and development of CBM and also guide the study of pore structures of other unconventional gas reservoirs.

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Section: Geological Backgroundmentioning

confidence: 99%

Pore Structure Characteristics of Coal and Their Geological Controlling Factors in Eastern Yunnan and Western Guizhou, China

Qin

You

et al. 2020

ACS Omega

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“…The sampling area, the Western Guizhou and the eastern Yunan Province, is an important coal production base and has abundant CBM resources (Yang et al, 2018;Xu et al, 2019;Zhang et al, 2018). The Tucheng and the Laochang coal mining areas are located in the Southwest and Northeast of the region, respectively (Fig.…”

Section: Geological Settingsmentioning

confidence: 99%

Volume and Surface Distribution Heterogeneity of Nano‐pore in Coal Samples by CO₂ and N₂ Adsorption Experiments

Zhang

Wei

Luo

et al. 2020

Acta Geologica Sinica (Eng)

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In this paper, the heterogeneity of adsorption pores in middle and high rank coal samples were analyzed by using low temperature N 2 and CO 2 adsorption technology and fractal theory. The following results were achieved. 1) According to the results of volume and surface fractal dimension, meso-pores can be classified into Mep-1, Mep-2, and Mep-3, respectively. Micro-pore can be classified into Mip-1, Mip-2, and Mip-3, respectively. 2) Pore types play an important role in affecting the heterogeneity of meso-pores. The volume heterogeneity (VHY) of Mep-1 is simpler than that of Mep-2 and Mep-3 in type A samples. However, the VHY of Mep-1 becomes gradually larger than that of Mep-2 and Mep-3 from type A to type B and C. The VHY of open pore in the same diameter is higher than that of semi-open or closed pore. Meanwhile, the surface heterogeneity (SHY) of types A and B samples is significantly larger than that of type C, the SHY of semi-open or closed pores is more complicated than that of open pores. 3) Coal rank mainly affects the heterogeneity of micro-pores. The heterogeneity of type A is always smaller than that of type B and C. The VHY of Mip-1 is more complicated than that of Mip-2 and Mip-3 in the same samples, and the sensitivity of the VHY of Mip-1 and Mip-2 to the degree of coal rank is smaller than that of Mip-3. Meanwhile, the SHY of Mip-1 and Mip-2 is simpler than that of Mip-3 in the same sample, the SHY of micro-pores remains stable as the pore size decreases, and the affect of coalification level on SHY decreases with the decrease in pore diameter. Full-scale fractal characterization has enabled quantitative characterization of adsorption pore properties and provided useful information with regards to the similarity of pore features in different coal reservoirs.

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“…The Upper Permian coal-bearing strata in western Guizhou possess abundant CBM resources. This area has been a hotspot of CBM development and research in China (Qin et al, 2012;Yang et al, 2018;Guo et al, 2020). The Bide-Santang basin is located in western Guizhou Province and has a total area of 1692 km 2 and a predicted coal-bearing area of 1000 km 2 (Fig.…”

Section: Geological Settingsmentioning

confidence: 99%

Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

Guo

Qin

et al. 2020

Acta Geologica Sinica (Eng)

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The methods of nuclear magnetic resonance (NMR) spectroscopy, mercury injection porosimetry (MIP), and gas -water relative permeability (GWRP) were used to reveal the pore structure and permeability characteristics of high-rank coal reservoirs in the Bide-Santang basin, western Guizhou, South China, to provide guidance for coalbed methane (CBM) exploration and exploitation and obtain direct insights for the development of CBM wells. The results indicate that the coal reservoirs in the study area are characterized by well-developed adsorption pores and poorly developed seepage pores. The bimodal NMR transverse relaxation time (T 2 ) spectra and the mutation in the fractal characteristic of the MIP pore volume indicate poor connectivity between the adsorption pores and the seepage pores. As a result, the effective porosity is relatively low, with an average of 1.70%. The irreducible water saturation of the coal reservoir is relatively high, with an average of 66%, leading to a low gas relative permeability under irreducible water saturation. This is the main reason for the low recovery of high-rank CBM reservoirs, and effective enhanced CBM recovery technology urgently is needed. As a nondestructive and less time-consuming technique, the NMR is a promising method to quantitatively characterize the pores and fractures of coals.

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Optimization methods of production layer combination for coalbed methane development in multi-coal seams

Cited by 79 publications

References 2 publications

Pore Structure Characteristics of Coal and Their Geological Controlling Factors in Eastern Yunnan and Western Guizhou, China

Pore Structure Characteristics of Coal and Their Geological Controlling Factors in Eastern Yunnan and Western Guizhou, China

Volume and Surface Distribution Heterogeneity of Nano‐pore in Coal Samples by CO₂ and N₂ Adsorption Experiments

Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

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Optimization methods of production layer combination for coalbed methane development in multi-coal seams

Cited by 79 publications

References 2 publications

Pore Structure Characteristics of Coal and Their Geological Controlling Factors in Eastern Yunnan and Western Guizhou, China

Pore Structure Characteristics of Coal and Their Geological Controlling Factors in Eastern Yunnan and Western Guizhou, China

Volume and Surface Distribution Heterogeneity of Nano‐pore in Coal Samples by CO2 and N2 Adsorption Experiments

Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

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Volume and Surface Distribution Heterogeneity of Nano‐pore in Coal Samples by CO₂ and N₂ Adsorption Experiments