Experimental investigation on pores and permeability variation characteristics of coal treated by chemical solvents

Chunshan Zheng; Feng Liao; Sheng Xue; Bingyou Jiang; Xuanping Gong; Baiqing Han; Zhongwei Chen

doi:10.1016/j.geoen.2023.211514

Experimental investigation on pores and permeability variation characteristics of coal treated by chemical solvents

Chunshan Zheng
, Feng Liao
, Sheng Xue
, Bingyou Jiang
, Xuanping Gong
, Baiqing Han
, Zhongwei Chen

Anhui University of Science and Technology
Hefei Comprehensive National Science Center
Ltd.
China Coal Xinji Energy Group Corporation
University of Queensland

Research output: Contribution to journal › Article › peer-review

18 Scopus citations

Abstract

Enhancing coal permeability by adopting chemical solvents treatment is one of the most effective methods to improve coalbed methane production efficiency in deep coal reservoirs with low permeability. However, coal pores and permeability variation characteristics affected by chemical solvents is not quantitatively determined. In this study, after being treated with carbon disulfide (CS₂), acetone (C₃H₆O) and N-methyl pyrrolidone (NMP), changes in coal ultrasonic characteristics were investigated. Relationship between ultrasonic parameter variations and coal fracture development was revealed. Meanwhile, through adopting nuclear magnetic resonance (NMR) and permeability testing equipment, coal pore structure, porosity and permeability changes were studied. Results show that after treated by three chemical solvents, ultrasonic velocity in coal reduces by 7.7%–51.2%, while ultrasonic attenuation coefficient increases by 4.22dB/m-123.8 dB/m, indicating that coal fractures experience good development. Moreover, NMR signal quantity of treated coal under saturated state rises significantly, with big growth in mesopore and macropore peaks. Compared with NMP and acetone, CS₂-treated coal porosity experiences the maximum increase of 7.71%, while the corresponding permeability growth is also the largest of 69.565 × 10⁻¹⁵m². Permeability changes obtained from NMP calculation model is basically consistent with that acquired by lab measurement. Furthermore, changes in extraction rate, ultrasonic parameters, pore fracture characteristics and permeability results of solvent-treated coal are mutually consistent. This verifies that chemical solvents could dissolve molecular substances in coal, effectively increase primary fractures and change small pores to mesopores and macropores, as well as improving pore connectivity. As a result, coalbed methane extraction performance is expected to be enhanced due to increased coal permeability.

Original language	English
Article number	211514
Journal	Geoenergy Science and Engineering
Volume	223
DOIs	https://doi.org/10.1016/j.geoen.2023.211514
State	Published - Apr 2023
Externally published	Yes

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy

Keywords

Chemical solvents
Coal pores
Coalbed methane
Permeability enhancement

Access to Document

10.1016/j.geoen.2023.211514

Cite this

@article{78d1a06d90d64f199ff05af99c99b27a,

title = "Experimental investigation on pores and permeability variation characteristics of coal treated by chemical solvents",

abstract = "Enhancing coal permeability by adopting chemical solvents treatment is one of the most effective methods to improve coalbed methane production efficiency in deep coal reservoirs with low permeability. However, coal pores and permeability variation characteristics affected by chemical solvents is not quantitatively determined. In this study, after being treated with carbon disulfide (CS2), acetone (C3H6O) and N-methyl pyrrolidone (NMP), changes in coal ultrasonic characteristics were investigated. Relationship between ultrasonic parameter variations and coal fracture development was revealed. Meanwhile, through adopting nuclear magnetic resonance (NMR) and permeability testing equipment, coal pore structure, porosity and permeability changes were studied. Results show that after treated by three chemical solvents, ultrasonic velocity in coal reduces by 7.7\%–51.2\%, while ultrasonic attenuation coefficient increases by 4.22dB/m-123.8 dB/m, indicating that coal fractures experience good development. Moreover, NMR signal quantity of treated coal under saturated state rises significantly, with big growth in mesopore and macropore peaks. Compared with NMP and acetone, CS2-treated coal porosity experiences the maximum increase of 7.71\%, while the corresponding permeability growth is also the largest of 69.565 × 10−15m2. Permeability changes obtained from NMP calculation model is basically consistent with that acquired by lab measurement. Furthermore, changes in extraction rate, ultrasonic parameters, pore fracture characteristics and permeability results of solvent-treated coal are mutually consistent. This verifies that chemical solvents could dissolve molecular substances in coal, effectively increase primary fractures and change small pores to mesopores and macropores, as well as improving pore connectivity. As a result, coalbed methane extraction performance is expected to be enhanced due to increased coal permeability.",

keywords = "Chemical solvents, Coal pores, Coalbed methane, Permeability enhancement",

author = "Chunshan Zheng and Feng Liao and Sheng Xue and Bingyou Jiang and Xuanping Gong and Baiqing Han and Zhongwei Chen",

note = "Publisher Copyright: {\textcopyright} 2023",

year = "2023",

month = apr,

doi = "10.1016/j.geoen.2023.211514",

language = "英语",

volume = "223",

journal = "Geoenergy Science and Engineering",

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TY - JOUR

T1 - Experimental investigation on pores and permeability variation characteristics of coal treated by chemical solvents

AU - Zheng, Chunshan

AU - Liao, Feng

AU - Xue, Sheng

AU - Jiang, Bingyou

AU - Gong, Xuanping

AU - Han, Baiqing

AU - Chen, Zhongwei

PY - 2023/4

Y1 - 2023/4

N2 - Enhancing coal permeability by adopting chemical solvents treatment is one of the most effective methods to improve coalbed methane production efficiency in deep coal reservoirs with low permeability. However, coal pores and permeability variation characteristics affected by chemical solvents is not quantitatively determined. In this study, after being treated with carbon disulfide (CS2), acetone (C3H6O) and N-methyl pyrrolidone (NMP), changes in coal ultrasonic characteristics were investigated. Relationship between ultrasonic parameter variations and coal fracture development was revealed. Meanwhile, through adopting nuclear magnetic resonance (NMR) and permeability testing equipment, coal pore structure, porosity and permeability changes were studied. Results show that after treated by three chemical solvents, ultrasonic velocity in coal reduces by 7.7%–51.2%, while ultrasonic attenuation coefficient increases by 4.22dB/m-123.8 dB/m, indicating that coal fractures experience good development. Moreover, NMR signal quantity of treated coal under saturated state rises significantly, with big growth in mesopore and macropore peaks. Compared with NMP and acetone, CS2-treated coal porosity experiences the maximum increase of 7.71%, while the corresponding permeability growth is also the largest of 69.565 × 10−15m2. Permeability changes obtained from NMP calculation model is basically consistent with that acquired by lab measurement. Furthermore, changes in extraction rate, ultrasonic parameters, pore fracture characteristics and permeability results of solvent-treated coal are mutually consistent. This verifies that chemical solvents could dissolve molecular substances in coal, effectively increase primary fractures and change small pores to mesopores and macropores, as well as improving pore connectivity. As a result, coalbed methane extraction performance is expected to be enhanced due to increased coal permeability.

AB - Enhancing coal permeability by adopting chemical solvents treatment is one of the most effective methods to improve coalbed methane production efficiency in deep coal reservoirs with low permeability. However, coal pores and permeability variation characteristics affected by chemical solvents is not quantitatively determined. In this study, after being treated with carbon disulfide (CS2), acetone (C3H6O) and N-methyl pyrrolidone (NMP), changes in coal ultrasonic characteristics were investigated. Relationship between ultrasonic parameter variations and coal fracture development was revealed. Meanwhile, through adopting nuclear magnetic resonance (NMR) and permeability testing equipment, coal pore structure, porosity and permeability changes were studied. Results show that after treated by three chemical solvents, ultrasonic velocity in coal reduces by 7.7%–51.2%, while ultrasonic attenuation coefficient increases by 4.22dB/m-123.8 dB/m, indicating that coal fractures experience good development. Moreover, NMR signal quantity of treated coal under saturated state rises significantly, with big growth in mesopore and macropore peaks. Compared with NMP and acetone, CS2-treated coal porosity experiences the maximum increase of 7.71%, while the corresponding permeability growth is also the largest of 69.565 × 10−15m2. Permeability changes obtained from NMP calculation model is basically consistent with that acquired by lab measurement. Furthermore, changes in extraction rate, ultrasonic parameters, pore fracture characteristics and permeability results of solvent-treated coal are mutually consistent. This verifies that chemical solvents could dissolve molecular substances in coal, effectively increase primary fractures and change small pores to mesopores and macropores, as well as improving pore connectivity. As a result, coalbed methane extraction performance is expected to be enhanced due to increased coal permeability.

KW - Chemical solvents

KW - Coal pores

KW - Coalbed methane

KW - Permeability enhancement

UR - https://www.scopus.com/pages/publications/85159764795

U2 - 10.1016/j.geoen.2023.211514

DO - 10.1016/j.geoen.2023.211514

M3 - 文章

AN - SCOPUS:85159764795

SN - 2949-8910

VL - 223

JO - Geoenergy Science and Engineering

JF - Geoenergy Science and Engineering

M1 - 211514

ER -

Experimental investigation on pores and permeability variation characteristics of coal treated by chemical solvents

Abstract

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Keywords

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