Theoretical Technology, Exploration and Development Progress, and Prospect of Coal-rock Gas in China

doi:10.3969/j.issn.1672-7703.2025.04.001

Abstract

Abstract: As a new type of unconventional natural gas resource, the exploration and development of coal-rock gas is of great significance for ensuring China’s energy security. This paper systematically elaborates on the research progress of coal-rock gas geological theories, key technologies, current status of exploration and development, and prospects for its development. The research shows that: ① A consensus has been basically reached in the industry on the connotation of the new type of coal-rock gas. It is clarified that coal rock is a typical dualporosity reservoir, and coal-rock gas reservoirs are characterized by high free gas content, oil-bearing in some reservoirs, and migration and accumulation of coal-rock gas in multi-fractured coal reservoirs. Effective reservoir formation requires good preservation conditions. ② The understanding of coal-rock gas accumulation mechanism and the theoretical framework of the whole petroleum system of coal-measure are taking shape. Based on the particularity of coal dual-porosity reservoirs, the action mechanism of fluid dynamic fields in different media is analyzed, and the understanding of the “three-field control” accumulation mechanism of coal-rock gas is initially formed. Two types of accumulation models, “source-reservoir integration and box-type sealing” and “multi-source co-storage and high-point enrichment”,are established, and the whole petroleum system of coal-measure is initially constructed. ③ In response to the characteristics of coal-rock gas reservoirs, a series of technologies have been initiallyformed, including geological-engineering sweet spot evaluation, experimental testing, horizontal well multi-stage fracturing, productivity evaluation and production optimization. Technologies such as three-dimensional development of multi-layer and multi-gas in coal measures and water-free reservoir reconstruction are actively explored. These technologies have supported the cumulative proven coal-rock gas geological reserves of 596.8×10⁹m³ nationwide, with the 2024 output reaching 2.7×10⁹m³. ④ It is preliminarily estimated that the national coal-rock gas geological resources exceed 30×1012 m3, with the development prospect of achieving an annual output of 30×10⁹ m³ by 2035, which will become a new growth pole of the natural gas industry. The current “three major challenges” in coal-rock gas exploration and development are clarified. It is proposed that future efforts should be made to strengthen theoretical and technological research in six key directions: coal-rock gas accumulation mechanism and construction of whole petroleum system of coal-measure, coal-rock gas selection and sweet spot evaluation technology, fluid seepage mechanism and migration law in coal rock, full-life cycle development optimization of coal-rock gas, coal rock mechanical characteristics and fracture propagation law, and efficient drilling, completion and reservoir reconstruction, so as to promote the high-quality development of the coal-rock gas industry.

Key words: coal-rock gas, geological characteristics, accumulation theory, exploration and development, key technologies, resource potential;development prospect, whole petroleum system of coal-measure, three-dimensional development of coal-measure multi-layers

CLC Number:

TE122.1

Li Guoxin, He Xinxing, Zhao Qun, Zhang Junfeng, Zhang Guosheng, Zhang Lei, Xu Wanglin, Zhang Bin, Yang Zhi. Theoretical Technology, Exploration and Development Progress, and Prospect of Coal-rock Gas in China[J]. China Petroleum Exploration, 2025, 30(4): 1-16.

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