Pilot experiment for underground in-situ pyrolysis of tar-rich coal in the northern Shaanxi Province

Authors

DUAN Zhonghui, Key Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, Xi’an 710021, China; Shaanxi Coal Geology Group Co., Ltd., Xi’an 710021, ChinaFollow
YANG Fu, Key Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, Xi’an 710021, China; Shaanxi Coal Geology Group Co., Ltd., Xi’an 710021, ChinaFollow
WANG Zhendong, Key Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, Xi’an 710021, China; Shaanxi Coal Geology Group Co., Ltd., Xi’an 710021, China
MA Li, Key Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, Xi’an 710021, China; Shaanxi Coal Geology Group Co., Ltd., Xi’an 710021, China
DUAN Xiaoqing, Shaanxi 185 Coalfield Geology Co., Ltd., Yulin 719000, China
CAO Husheng, Shaanxi 185 Coalfield Geology Co., Ltd., Yulin 719000, China
CHEN Liang, Shaanxi 185 Coalfield Geology Co., Ltd., Yulin 719000, China

Abstract

Objective The breakthrough of the pilot experiment for underground in-situ pyrolysis of tar-rich coal in the northern Shaanxi has added new vitality to the research on in-situ conversion of fossil energy such as tar-rich coal and oil shale, and the results have attracted wide attention both inside and outside the industry. The research on underground in-situ pyrolysis of tar rich coal is still in its infancy, lacking systematic research on field engineering data.Methods Based on the pilot experiment, the main geological conditions and engineering difficulties have been clarified, and the progress of underground in-situ pyrolysis has been summarized. The next technical breakthrough directions are also discussed. Results and Conclusions The results show that: (1) The superior geological conditions of the pilot experiment area, such as stable coal seams, good coal quality, high tar yield of coal seams, large oil generation potential, weak water-rich coal measures and large thickness of aquiclude. However, there are some factors affecting the engineering implementation, such as poor connectivity of coal seam pores, low diversion capacity, poor thermal conductivity of coal seams, difficulty in efficient heating, difficulty in coal reservoir reconstruction, and high requirements for volume .fracturing; (2) Comprehensive geological evaluation is conducive to avoiding the influence of unfavorable factors such as formation water and faults on the underground pyrolysis process. Controllable shock wave fracturing technology is helpful for the connectivity of underground coal seams. The stable operation of efficient underground electric heaters is the key to efficient oil production. (3) After one month of heating operation, the world's first barrel of underground in-situ pyrolysis oil was extracted, which opened up the technical path of underground in-situ pyrolysis extraction of tar-rich coal and initially obtained the underground temperature, pressure and other process parameters for efficient oil production. The pilot experiment has a short heating cycle, low oil production and high energy consumption, lacks a technical systematic evaluation of project operation.It is necessary to continue upgrading technologies in terms of developing efficient underground electric heaters, underground coal seam volume fracturing, pyrolysis-gasification integration, comprehensive utilization of heat energy and integrated CCS, so as to comprehensively improve the economy, safety and reliability of underground in-situ pyrolysis extraction of tar-rich coal.

Keywords

tar-rich coal, underground in-situ pyrolysis, pilot experiment, pyrolytic-gasification integration, northern Shaanxi Province

DOI

10.12363/issn.1001-1986.24.05.0362

Recommended Citation

DUAN Zhonghui, YANG Fu, WANG Zhendong, et al. (2024) "Pilot experiment for underground in-situ pyrolysis of tar-rich coal in the northern Shaanxi Province," Coal Geology & Exploration: Vol. 52: Iss. 7, Article 3.
DOI: 10.12363/issn.1001-1986.24.05.0362
Available at: https://cge.researchcommons.org/journal/vol52/iss7/3

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