During coal gas reservoir well drilling and completions and stimulations, the contact of different types of working liquid with the reservoir and interaction with each other will impact the stress sensitivity of reservoir. Coal samples tested were cored from moderate coal rank in Ningwu basin, after fracturing, the coal samples were soaked in different working fluids, and then were tested for stress sensitivity by increasing and reducing confining pressure. The results show that stress sensitivity of fractured coal sample is 0.73, the stress sensitivity of core samples with working fluid intrusion is 0.79~0.94, the stress sensitivity of coal is greater than tight sandstone and shale before and after being damaged by working fluid. In combination with rock mechanic test results, the fracture development of coal is favorable to the invasion of the working fluid, after being effected by working liquid coal strength reduces, making crack easier to close and strengthening the stress sensitivity of coal reservoirs. Research results can provide basic parameters for coalbed reservoir protection during coalbed methane well drilling and completion, stimulation and exploitation.%煤岩气藏钻井、完井和增产改造等环节，不同类型工作液与储层接触相互作用，必将对储层的应力敏感性产生影响。选取宁武盆地中煤阶煤岩，系统开展了不同类型工作液作用人造裂缝煤样的应力敏感性试验。试验结果表明，人造裂缝煤样应力敏感系数为0.73，工作液作用后应力敏感系数为0.79~0.94。通过应力敏感系数对比分析表明，工作液作用下煤岩的应力敏感性强于致密砂岩和页岩。结合岩石力学试验结果可知，煤岩裂隙发育有利于工作液的侵入，工作液作用后煤岩强度降低使裂缝更容易闭合，强化了煤岩储层的应力敏感性。研究成果可为煤层气井钻完井、增产改造和开采过程中煤层气储层保护提供基础参数。
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