Due to the limited permeability and high methane content of the majority of China’s coal seams, significant coal mining gas disasters frequently occur. There is an urgent need to artificially improve the permeability of coalbed methane (CBM) reservoirs, enhance the recovery efficiency of CBM and prevent mine gas accidents. As a novel coal rock fracture technology, the CO₂ phase transition jet (CPTJ) has been widely used due to its advantages of safety and high fragmentation efficiency. In this study, to ascertain the effects of the pressure of CPTJ fracturing, the influence of its jet pressure on cracked coal rock was revealed, and its effect on CBM extraction was clarified. In this research, the law of CPTJ pressure decay with time was investigated using experimental and theoretical methods. Based on the results, the displacement and discrete fracture network law of CPTJ fracturing coal rock under different jet pressure conditions were studied using particle flow code numerical simulation. Finally, field experiments were conducted at the Shamushu coal mine to assess the efficiency of CPTJ in enhancing CBM drainage. The results showed that the pressure of the CPTJ decreased exponentially with time and significantly influenced the number and expansion size of cracks that broke coal rock but not their direction of development. CPTJ technology can effectively increase the number of connected microscopic pores and fractures in CBM reservoirs, strongly increase the CBM drainage flow rate by between 5.2 and 9.8 times, and significantly reduce the CBM drainage decay coefficient by between 73.58% and 88.24%.

由于我国大部分煤层渗透率有限、瓦斯含量高，重大煤矿瓦斯灾害频发。迫切需要人为提高煤层气藏渗透率，提高煤层气采收率，预防矿井瓦斯事故。CO _{2煤岩破碎技术作为一种新型煤岩破碎技术}相变射流(CPTJ)因其安全、破碎效率高等优点而得到广泛应用。本研究旨在明确CPTJ压裂压力的影响，揭示其射流压力对裂隙煤岩的影响，明确其对煤层气抽采的影响。本研究采用实验和理论方法研究了CPTJ压力随时间衰减的规律。在此基础上，采用颗粒流程序数值模拟研究了不同射流压力条件下CPTJ压裂煤岩的位移和离散裂隙网络规律。最后，在沙木树煤矿进行了现场实验，以评估 CPTJ 增强煤层气抽采的效率。结果表明，CPTJ的压力随时间呈指数下降，显着影响破坏煤岩的裂缝的数量和扩展尺寸，但不影​​响其发展方向。CPTJ技术可以有效增加煤层气储层连通的微观孔隙和裂缝的数量，使煤层气排水流量大幅提高5.2~9.8倍，显着降低煤层气排水衰减系数73.58%~88.24%。