我国煤层气资源丰富，但煤储层多为低渗致密储层，单井产量和采出率普遍较低，现有的技术手段难以支撑我国煤层气产业的快速发展，需要探索提高单井产量和采出率的手段。除了水力压裂、裸眼洞穴完井的物理改造方式，采用化学法改造原始煤储层物性也是近年研究的热点。煤储层酸化氧化技术可以避免物理增产方式造成的储层伤害，并可以促进解吸并改善渗流能力，但对于不同煤阶煤储层，适宜不同煤阶煤储层的酸化氧化试剂需要优化，以及其酸化氧化的作用效果需要评价。通过室内实验，对比分析了保德、沐爱、新疆区块煤样物性特征，包括煤阶、煤体结构、煤的宏观特征、煤质特征、孔渗参数、元素分析、矿物组成方面的区别；通过煤粉酸液前置溶蚀实验，优选出了盐酸最佳浓度，并通过Design-Expert软件设计并开展了五因素三水平的酸液优选正交实验，找出了影响溶蚀效果的敏感因素，优选出了最优的氧化剂类型，并对保德、沐爱、新疆区块煤样，分别优选出了适用于各区块煤储层的酸化氧化试剂体系；应用优选出的各区块酸化氧化试剂体系，对保德、沐爱、新疆区块煤样，分别对比分析了酸化氧化前后的孔隙度、渗透率和润湿性；最后基于沐爱区块一个典型井组，通过数值模拟预测了酸化氧化改造后的产气效果。实验表明：盐酸浓度在3~4 mol/L内，酸液溶蚀效果最好；5个实验因素的影响效果从大到小依次是浸泡时间、酸液种类、浸泡温度、煤样种类、酸液浓度；最优的氧化剂为质量分数3%的过氧化氢溶液；保德区块混合酸化氧化剂配方为10%HCl+2%CH₃COOH+2%HF+3%H₂O₂，沐爱区块的最佳混合酸化氧化剂配方为8%HCl+ 2%CH₃COOH+ 4%HF+ 3%H₂O₂，新疆区块的最佳混合酸化氧化剂配方为12%HCl+1%CH₃COOH+1%HF+3%H₂O₂，煤阶越高，最优酸化氧化试剂体系中HF含量越高。酸化和氧化对煤样的孔隙度和渗透率有提升作用，2者增大规律一致，低阶煤提升效果优于高阶煤。酸化作用使煤的亲水性增强，而氧化作用使煤的亲水性大幅减弱，经优选的酸化氧化体系处理的煤样亲水性减弱。数值模拟预测表明酸化氧化方案生产10 a达到废弃条件时采出率达到了64.64%，与同一时间未进行酸化氧化方案的采出程度相比增加19.72%，增产效果显著；与未进行酸化氧化方案生产18 a达到废弃条件时采出率相比增加0.97%，但酸化氧化措施节省了8 a生产时间达到最终采出率，降低了矿场运营成本。优选出的适宜于低、中、高不同煤阶煤层气藏的酸化氧化体系，改善了目标煤储层的解吸和渗流能力，提高了单井产量和采出率。

China has abundant coalbed methane (CBM) resources, and most of them are low-permeability and tight reservoirs, with generally low production rate and small recovery factor. Existing technologies face great challenges to meet the demand on CBM in China. It is desirable to develop new methods to improve the production rate and enhance recovery factor. In addition to physical stimulation methods such as hydraulic fracturing and open-hole cave completion, the use of chemical methods to improve physical properties of coal reservoirs has also been a hot research topic in recent years. Coal reservoir acidification and oxidation technology can promote desorption of gas and enlarge permeability of reservoir. But for different coal rank coal reservoirs, the acidification and oxidation agents need to be optimized and their performance evaluated. Laboratory experiments are conducted to compare and analyze the physical properties coal samples from Baode, Mu’ai, and Xinjiang blocks, including coal rank, texture, macroscopic characteristics, quality, porosity, permeability, element, and mineral composition. The optimal concentration of hydrochloric acid is determined through pre-dissolution experiment of coal powder in acid solution. Then a five-factor and three-level orthogonal experiment for acid solution optimization is designed and performed by using Design-Expert software, which identifies the sensitive factors affecting the dissolution. For the coal samples in Baode, Mu’ai, and Xinjiang blocks, the oxidant types and the corresponding acidification and oxidation agent systems are optimized. Applying these acidification and oxidation agent systems to coal samples from Baode, Mu’ai, and Xinjiang blocks, the change of porosity, permeability, and wettability are compared and analyzed. Finally, through numerical simulation, the gas production is predicted for acidification and oxidation in typical well group in Block Mu’ai. Results show that the acid solution has the best dissolution at a concentration of hydrochloric acid of 3 mol/L to 4 mol/L; Top factors played in the experiment are soaking time, acid type, soaking temperature, coal sample type, and acid concentration, in descending order of importance; The optimal oxidant is a hydrogen peroxide solution with a concentration of 3%; the mixed acidification oxidant formula in Baode block is 10% HCl + 2% CH₃COOH + 2% HF + 3% H₂O₂; The optimal mixed acidification oxidant formula in Mu’ai block is 8% HCl + 2% CH₃COOH + 4% HF + 3% H₂O₂; the optimal mixed acidification oxidant formula in Xinjiang block is 12% HCl + 1% CH₃COOH + 1% HF + 3% H₂O₂; The higher the coal rank, the greater the HF content in the optimal acidification oxidant system. Both acidification and oxidation improve the porosity and permeability of coal samples to some extent, and the improvement in low-rank coal is more significant than that in high-rank coal. Acidification and oxidation have different effects on the wettability of coal: Acidification increases the hydrophilicity of coal, whereas oxidation reduce the hydrophilicity of coal; and the hydrophilicity of coal samples treated by the optimized acidification and oxidation system is weakened. Reservoir simulation results show that acidification and oxidation lead to a recovery factor of 64.64% after 10 years of production, which is 19.72% higher than that without acidification and oxidation. The advantage of acidification and oxidation is 0.97% after 18 years of production. However, the acidification and oxidation saved 8 years of production time to achieve a close final recovery factor, which greatly reduces the operating costs. The optimized acidizing oxidation agent systems for CBM reservoirs with low, medium, and high ranks improved the desorption and permeability of the target reservoirs, and increase well production and recovery factor. This research provides technical support for stimulation practices of CBM reservoirs in the aforementioned blocks in China, as well as similar coal reservoirs in the world.