一体化穿层压裂是实现近距离煤系储层多气共采的关键技术，但常规低黏活性水压裂液易沟通层理等弱结构面，限制了水力裂缝纵向穿层扩展。鉴于此，基于泡沫流体高黏、低滤失和易返排等特性，提出N₂泡沫低伤害穿层压裂煤系储层方法，通过室内浇筑灰岩、页岩与真实煤样的组合体试样，利用自行研制的大尺寸真三轴压裂渗流模拟装置，分别开展N₂泡沫与活性水的真三轴压裂物理模拟实验，对比分析2种压裂介质泵压曲线、压后裂缝形态、缝网导流能力以及主裂缝面粗糙度特征，研究N₂泡沫压裂裂缝起裂特征及垂向扩展行为。实验结果表明：① 高黏与低滤失N₂泡沫压裂液穿层扩展能力强于活性水，相同应力条件下纵向穿层数量更多，但泵压曲线压力峰值低于后者，有利于穿层压裂施工；② 相比活性水，可压缩N₂泡沫流体压裂增压时间更长，且其页岩层破裂压力高于前者约8.7 MPa；③ 压裂完成后，原位应力条件下N₂泡沫压后缝网的重注压力较活性水低3.6 MPa，表明N₂泡沫压裂形成的缝网导流能力更高；④ N₂泡沫与活性水压裂主裂缝面粗糙度分别为20.53和13.56，更粗糙的裂缝面有利于生产过程缝网导流能力的保持。结论认为，可压缩N₂泡沫以其高黏与低滤失特性可实现更好的纵向穿层效果，但横向缝网复杂程度相对较低，建议现场采取“泡沫造主缝+气体/活性水压裂造分支缝”复合压裂工艺，实现多岩性煤系储层的一体化穿层压裂与缝网改造。

Integrated layer-penetration fracturing method is a key technology to realize multi-gas co-production in close-layered coal measure strata. Low-viscosity active water is prone to activate weak structural planes, restricting fracture height containment. In view of this, based on the characteristics of high viscosity, low filtration and high flow-back efficiency of foam fluid, a method of N₂ foam low-damage layer-penetration fracturing coal measure strata is proposed. Using the self-developed large-scale true triaxial hydraulic fracturing seepage simulation device, the N₂ foam and active water fracturing are carried out with layered samples, which is combined with limestone, shale and real coal samples, respectively. The injection pressure curve, fracture morphology, fracture network conductivity and main fracture surface roughness characteristics of the two fracturing media are compared and analyzed, and the fracture initiation characteristics and vertical propagation behavior of N₂ foam fracturing are studied. The test results show that: ① The lay-penetration ability of high-viscosity and low-filtration N₂ foam is stronger than that of active water, under the same in-situ stress condition, the number of penetration layers of foam fracturing is more but the peak pressure during fracturing is lower, in favor of layer-penetration fracturing operation. ② Compared to the active water, the pressurization time of high-compressible foam fracturing is longer, and breakdown pressure in the shale layer is 8.7 MPa higher than that of active water. ③ After fracturing, the re-injection pressure of fracture network after N₂ foam fracturing is 3.6 MPa lower than that of active water under in-situ stress condition, indicating that the flow conductivity of fracture network by N₂ foam fracturing is higher. ④ The roughness of the main fracture surface induced by N₂ foam and active water fracturing is 20.53 and 13.56, respectively, the former is more conducive to maintain the flow conductivity in the production process. It is concluded that foam with high viscosity and low filtration characteristics can achieve a better layer-penetration effect, but the complexity of fracture network is relatively low. It is suggested to adopt the hybrid fracturing process of “foam fracturing for main fracture and gas/active water fracturing for branch fracture” to realize the integrated layer-penetration fracturing and fracture network reconstruction in the coal measure strata.