二次压裂是煤层气开采中初次裂缝产量下降时有效增产手段。为研究煤层气储层二次压裂裂缝扩展规律、优化暂堵参数，开展了室内暂堵压裂模拟试验研究。使用大尺寸真三轴压裂模拟系统，样品尺寸为30 cm×30 cm×30 cm，采集沁水盆地煤岩后通过包裹混凝土得到标准试验样品。首先通过加载三轴应力模拟地层环境，后以恒定排量向井筒中注压裂液模拟初次压裂，初次压裂完成后采用CT扫描对岩样内部的初次裂缝形态进行扫描观测，将暂堵剂注入井筒内部并开展二次压裂试验；试验结束通过CT扫描裂缝形态分析二次压裂裂缝形态。试验结果表明:暂堵效果受暂堵剂粒径和用量影响较大。暂堵剂粒径过大，影响压裂液的悬砂效果，暂堵剂容易在井筒内堆积，导致二次压裂施工压力异常升高，暂堵剂粒径过小，难以形成有效封堵，二次压裂时裂缝以沿初次裂缝扩展为主。随着暂堵剂用量的提高，对初次裂缝的封堵效果增强，二次压裂破裂压力升高，促进二次压裂裂缝沿垂直初次裂缝方向的扩展；另一方面暂堵剂进入二次压裂裂缝后形成二次封堵，促进分支裂缝的形成，二次压裂复杂程度升高。研究认为通过暂堵压裂可以促进分支裂缝的形成，提高二次压裂裂缝的复杂程度，增大压裂改造面积提升二次压裂效果。二次压裂裂缝形态主要受暂堵剂粒径与初次压裂裂缝匹配程度及暂堵剂用量等因素影响。

Re-fracturing is an effective means of increasing production when the primary fracture declines in CBM exploitation. In order to study the crack propagation law of re-fracturing in coalbed methane reservoirs and optimize the parameters of temporary plugging, a simulation experiment of indoor temporary plugging and fracturing was carried out. In this study, a large-scale true triaxial fracturing simulation system was used, and the sample size was 30 cm × 30 cm × 30 cm. After collecting coal and rock in the Qinshui Basin, the standard experimental samples were obtained by wrapping concrete. The experiment first simulates the formation environment by loading triaxial stress, and then injects fracturing fluid into the wellbore with a constant displacement to simulate the initial fracturing. The plugging agent was injected into the wellbore and the re-fracturing experiment was carried out; at the end of the experiment, the fracture morphology of the re-fracturing was analyzed by CT scanning. The experimental results show that the temporary plugging effect is greatly affected by the particle size and dosage of the temporary plugging agent. The particle size of the temporary plugging agent is too large, which affects the sand suspension effect of the fracturing fluid. The temporary plugging agent is easy to accumulate in the wellbore, resulting in an abnormal increase in the re-fracturing construction pressure. The particle size of the temporary plugging agent is too small, and it is difficult to form effective plugging, during the re-fracturing, the fractures mainly propagate along the primary fractures. With the increase of the amount of temporary plugging agent, the plugging effect on the primary fracture is enhanced, and the rupture pressure of re-fracturing increases, which promotes the expansion of re-fracturing fractures in the direction perpendicular to the primary fracture; on the other hand, the temporary plugging agent enters the re-fracturing. After fracturing fractures, secondary plugging is formed, which promotes the formation of branched fractures and increases the complexity of re-fracturing. It is believed that temporary plugging and fracturing can promote the formation of branch fractures, improve the complexity of re-fracturing fractures, and increase the fracturing area to improve the effect of re-fracturing. The fracture morphology of the re-fracturing is mainly affected by factors such as the particle size of the temporary plugging agent and the matching degree of the primary fracturing fractures and the amount of the temporary plugging agent.