A Review of Research on Cavity Growth in the Context of Underground Coal Gasification

Huijun Fang, Yuewu Liu (), Tengze Ge, Taiyi Zheng (), Yueyu Yu, Danlu Liu, Jiuge Ding and Longlong Li
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Huijun Fang: China United Coalbed Methane National Engineering Research Center Co., Ltd., Beijing 100095, China
Yuewu Liu: Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Tengze Ge: China United Coalbed Methane National Engineering Research Center Co., Ltd., Beijing 100095, China
Taiyi Zheng: Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Yueyu Yu: China United Coalbed Methane National Engineering Research Center Co., Ltd., Beijing 100095, China
Danlu Liu: China United Coalbed Methane National Engineering Research Center Co., Ltd., Beijing 100095, China
Jiuge Ding: Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Longlong Li: Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China

Energies, 2022, vol. 15, issue 23, 1-21

Abstract: Underground Coal Gasification (UCG) is a leading-edge technology for clean and effective utilization of coal resources, especially for deep coal seams with a depth of more than 1000 m. Since the core operation place of UCG is the cavity, mastering the cavity growth pattern is a prerequisite to ensure the efficient and economic development of UCG. At present, scholars have conducted numerous research works on cavity growth, but the simulation conditions limit the research results. Hence, it is necessary to summarize and sort out the research results of cavity growth patterns, which contribute to deepening the understanding of UCG and pointing out the direction for subsequent research. First of all, this paper summarizes the development history of UCG technology and describes the cavity growth mechanism from chemical reactions and thermo-mechanical failure. Then, the research methods of cavity growth are summarized from three aspects: a field test, laboratory experiment, and numerical simulation. The results show that the appearance of the cavity is teardrop-shaped, and its growth direction is obviously related to the gas injection method, including the injection direction and rate. Subsequently, the factors affecting the cavity growth process are expounded from the geological factors (permeability, moisture content, and coal rank) and operating factors (temperature, pressure, gasification agent’s composition, and gasification agent’s flow pattern). Finally, the existing problems and development trends in the cavity growth are discussed. The follow-up research direction should focus on clarifying the cavity growth mechanism of the controlled-retractable-injection-point (CRIP) method of UCG in the deep coal seam and ascertain the influence of the moisture content in the coal seam on cavity growth.

Keywords: underground coal gasification; cavity growth; field test; laboratory experiment; numerical simulation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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