Optimization of coalbed methane recovery from extraction borehole using novel plastic spraying material: A field application and evaluation

High-quality gas extraction is confronting enormous difficulties due to the leakage of air from the roadway through the coal wall into the extraction system, particularly in the boreholes along the coal seam. In this work, a new set of material and technology for coal wall spraying and sealing was developed to block the air leakage channel and enhance the concentration of extracted gas. The material has excellent air-tightness, resilience, and flame retardancy, and the feasibility of the implementation of the technology was demonstrated by the application in Hexi Coal Mine. The results showed that: the gas-extracted concentration was lower than 10% after 70 days under the conventional borehole sealing method. However, the new material and technology could increase gas-extracted concentration by 26.9 similar to 43.7% with a maximum increase multiple of 4.090 times. Moreover, the average gas-extracted concentration can be increased to 76.7% and maintain a relatively stable state for 80 days. This technology could not only reduce the air leakage, but also strengthen the internal and external pressure difference of the borehole, so that more gas can be extracted at a high concentration, which is expected to provide a reference for the gas disaster control and high-quality gas source guarantee.

Automated summary

A new material and technology for coal wall spraying and sealing were developed to block air leakage and improve gas extraction concentration. The application in Hexi Coal Mine demonstrated the feasibility of this technology. Results showed that the new material and technology could increase gas extraction concentration by 26.9 to 43.7%, with a maximum increase multiple of 4.090 times. This technology has the potential to reduce air leakage, enhance pressure difference, and guarantee high-quality gas sources.