Abstract:

In order to swiftly elucidate the influence of internal parameters on the fracturing performance of a liquid CO₂ fracturing tool and optimize its functionality for enhanced coal seam gas extraction efficiency, a rapid assessment experimental apparatus was designed. A set of 9 orthogonal experiments involving 4 horizontal and 3 influencing factors was conducted utilizing a 38 mm mining-specific fracturing tool. The study analyzed the relative significance of the internal charge quantity in the heating tube, liquid CO₂ filling volume in the main pipe, the thickness of the fracture plate, and the caliber of the release aperture on the fracturing tool's performance. Furthermore, pivotal influencing factors were subjected to fixed-variable experiments to explore their impact patterns on the fracturing performance of the liquid CO₂ fracturing tool. Results indicate that, for the 38 mm mining-specific CO₂ fracturing tool, the thickness of the fracture plate exerts the most substantial influence on the fracturing tool's performance, followed by the internal charge quantity in the heating tube. The impact of the liquid CO₂ filling volume in the main pipe and the caliber of the release aperture is comparatively weaker. The fracturing performance of the liquid CO₂ fracturing tool gradually stabilizes with an increase in the thickness of the fracture plate, reaching a point where the plate does not rupture. When the internal parameters of the 38 mm fracturing tool are set to a CO₂ mass of 0.33 kg, a release caliber of 18 mm, a charge quantity of 60 g, and a fracture plate thickness of 2.0 mm, the tool's fracturing performance corresponds to a TNT(Trinitrotoluene) equivalent of 0.202 kg which is enhanced by 21.9 % compared to the current on-site parameters.

Key words: CO₂ fracturing tool, internal parameters, capacity to do work, liquid CO₂ filling volume, internal charge quantity in heating tube, thickness of fracture plate, caliber of release aperture