Abandoned Coal Mines Converted into Natural Gas Storage Facilities

Strategic Insights -

Abandoned underground coal mines can be transformed into efficient natural gas storage facilities with low construction costs and short construction periods. According to a recent study from the China University of Mining and Technology, the rapid growth in natural gas consumption worldwide has been accompanied by a significant demand for storage capacity. Researchers have proposed a simplified technical approach for converting abandoned room-and-pillar coal mines into natural gas storage facilities, which has shown promising results.

Key Takeaways:

  • The research study, funded by Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project, and the National Natural Science Foundation of China, aimed to investigate the feasibility of converting abandoned coal mines into natural gas storage facilities.
  • The study selected a coal mine as the setting to examine performance and effectiveness, and proposed a simplified technical approach for conversion.
  • The research found that the underground coal pillars and surrounding rock masses are at risk of movement and deformation under dual effects of injection-production pressures and creep effect.
  • The study presented and interpreted the rock movements, deformations, and fracture characteristics during the injection-production processes, showing that the instability risk increases when the injection-production pressure approaches in-situ conditions.
  • The research concluded that the findings provide theoretical underpinnings for conversion of abandoned coal mines to gas storage facilities from engineering practices.
  • The authors of the study, including Xuejie Deng, Xiaoming Shi, Yuan An, Jichu Wang, Shicong Li, Zhide Wu, Xifeng Liang, and Benjamin de Wit, have made significant contributions to the field of geomechanics for energy and the environment.

Statistics:

  • The initial deflection of the roof was 142.91 mm, increasing to 226.06 mm after 50 cycles.
  • The stress and resulting displacement on pillars showed 'arched' distributions after injection-production processes.
  • The difference in vertical displacement between the roof and pillars decreased from 108.22 mm to 91.28 mm as injection-production stress increased from 1.8 MPa to 8.2 MPa.
  • The proportional number of fractures in the overlying rock mass increased as more injection-production cycles were added.

Sources:

  • Researchers at China University of Mining and Technology, "Evolution of Rock Mass Stress, Movement, and Deformation During Injection-production Processes In Coal Mines That Have Been Converted Into Natural Gas Storage Facilities," published in Geomechanics for Energy and the Environment, 2025;43 (2025).
  • China University of Mining and Technology, Sch Energy & Min Engn, Beijing 100083, People's Republic of China, Xuejie Deng, contact person.