Application of Waterproof and Breathable Membrane in In-situ Detection Device for Methane Concentration in Shallow Gas

Shallow gas is a huge safety hazard in the exploration and exploitation of urban underground space as well as marine oil and gas resources. At this stage, the detection method for shallow gas is still based on drilling and sampling. In this paper, we study and design an in-situ detection device for shallow gas pressure and methane concentration based on waterproof and breathable membrane technology and non-dispersive infrared gas detection technology. The design of the mud-water-gas separation structure and the selection of materials are highlighted to achieve the extraction of surrounding shallow gas. The waterproof and pressure reduction experiments of the device were also carried out on the simulated high water pressure experimental platform built, and the results proved that the device still has good waterproof performance under high pressure environment, and the relationship between the internal pressure of the device and the actual environmental pressure was also analyzed. Through the data record analysis of the simulation experiment and the field shallow gas methane concentration experiment, the device has the advantages of waterproof, stable and accurate, which is suitable for the field detection of shallow gas pressure and methane concentration and meets the needs of related research work.