Experimental investigation of BLEVE in liquid CO2 phase-transition blasting for enhanced coalbed methane recovery

Abstract

Enhanced coalbed methane (ECBM) recovery by liquid carbon dioxide phase-transition blasting (LCO2-PB) has been considered as a viable methane recovery. However, the shock of the boiling liquid expanding vapor explosion (BLEVE) of CO2 during the fracturing process is still not clear, hindering the application of technology. In this paper, the pressure and temperature of LCO2-PB were characterized through a controlled BLEVE experiment using a cylindrical section. Three parameters were controlled during the experiments: the fill pressure, the blasting pressure and the release orifice on the tube. The results indicated that the maximum crushed radius of LCO2-PB occurred at the combination of parameters with the highest blasting pressure, medium filling level and maximum release orifice. The peak overpressure and the distance formed were increasing as the burst pressure increased and the filling pressure reduced respectively. The quasi-static effect increases with the increase of the blasting pressure and the reduction of the release orifice. The laboratory and field results all suggest that the action form of cracked coal can be controlled by adjusting initial parameters, which ensuring the extraction concentration and utilization rate, and reducing the natural emission of methane and greenhouse gas emissions.