Experimental study of cryogenic treatment of Karaganda coal samples


Wang L. Yessenbayev N. Yan X. Sarmalayev I. Cha M. Zhang D. Hazlett R.D.
September 2024KeAi Publishing Communications Ltd.

Petroleum Research
2024#9Issue 3359 - 368 pp.

Karaganda Coal Basin bears the largest undeveloped reserve of coalbed methane (CBM) in Kazakhstan, which lacks water resources for implementing large-volume hydraulic fracturing. Cryogenic fracturing utilizing liquid nitrogen (LN2) has been trialled in fields and is a waterless fracturing technique under intensive research these days. This study aimed to evaluate the cryogenic treatment efficacy of Karaganda coal samples as well as to understand the coal permeability evolution during the thawing period. X-ray fluorescent spectrometry (XRF) and microscope imaging identified the compositional and structural heterogeneities of coal specimens mined from different interlayers. Acoustic emission test, permeability measurement, and microscope imaging comparatively characterized the dry coal structure alteration before and after immersion into LN2. Cryogenic treatment slowed down the S-wave velocity through coal specimens, enhanced permeability by over 65 % after temperature recovery as well as created new fractures, enlarged existing ones, and spalled coal particles. Dynamic permeability evolution against temperature rise during the thawing process has been successfully captured for the first time. Overall, the experimental measurements support that the LN2 cryogenic fracturing technique would be effective in stimulating coalbeds for CBM production in Karaganda Coal Basin.

Acoustic emission , Cryogenic treatment , Dynamic permeability , Karaganda coal , Microscopic image , XRF composition

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State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, College of Energy, Chengdu University of Technology, 610059, China
Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil & Gas Reservoirs in West China, Ministry of Education, Xian Shiyou University, Xian, 710065, China
Petroleum Engineering Department, Nazarbayev University, 010000, Kazakhstan
Department of Civil Engineering, Jeju National University, 62343, South Korea
Department of Civil and Environmental Engineering, Nazarbayev University, 010000, Kazakhstan

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation
Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil & Gas Reservoirs in West China
Petroleum Engineering Department
Department of Civil Engineering
Department of Civil and Environmental Engineering

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