江堃,邓守春,李海波. 甲烷燃爆压裂技术的实验研究[J]. 煤炭学报,2023,48(12):4297−4307. DOI: 10.13225/j.cnki.jccs.ZC23.1134
引用本文: 江堃,邓守春,李海波. 甲烷燃爆压裂技术的实验研究[J]. 煤炭学报,2023,48(12):4297−4307. DOI: 10.13225/j.cnki.jccs.ZC23.1134
JIANG Kun,DENG Shouchun,LI Haibo. Experimental study on methane deflagration fracturing technology[J]. Journal of China Coal Society,2023,48(12):4297−4307. DOI: 10.13225/j.cnki.jccs.ZC23.1134
Citation: JIANG Kun,DENG Shouchun,LI Haibo. Experimental study on methane deflagration fracturing technology[J]. Journal of China Coal Society,2023,48(12):4297−4307. DOI: 10.13225/j.cnki.jccs.ZC23.1134

甲烷燃爆压裂技术的实验研究

Experimental study on methane deflagration fracturing technology

  • 摘要: 页岩气资源的高效开发事关我国现代化建设全局,承担着助力“双碳”目标实现的重要使命。鉴于水力压裂耗水量大以及压裂液造成地层不可逆污染,寻求一种更为科学绿色的压裂技术已成为国内外专家研究的热点。提出了采用甲烷原位燃爆压裂技术开发页岩气的新思路,该技术利用电火花点火使储层甲烷与泵入的助燃剂发生燃爆,依靠瞬间产生的高压冲击储层岩石进行压裂,使储层产生一定规模且不受地应力控制的复杂裂缝网络。其优势在于可以防止地层污染,减少地面运输费用,有望成为一种高效、环保的低成本无水压裂技术。利用自主设计的包括致裂装置、气体充装、点火控制和数据采集系统在内的甲烷燃爆压裂实验系统开展了大尺寸物模(ϕ2.0 m×1.5 m)的地面压裂实验,记录了致裂管内空腔压力和井壁压力时程曲线,并与爆炸压裂、水力压裂的井筒压力和成缝特征进行对比。结果表明:燃爆过程中管内膛压峰值为495.18 MPa,是充注压力的82.5倍;试样破碎度低且粉碎区小,主裂缝为7~9条,缝宽在厘米级;甲烷燃爆压裂致裂能量充足、影响范围大、对井筒的损害程度可由充注压力控制;与爆炸压裂和水力压裂相比,该技术拥有更长的高压作用时间,更有利于裂缝起裂扩展,裂缝数量多于水力压裂,长度优于爆炸压裂,可获得最佳压裂效果。通过实验研究记录了高初始压力下甲烷−氧气混合物发生燃爆达到的峰值压力和升压速率,验证了甲烷原位燃爆压裂技术开发页岩气的可行性,可为该技术未来的实际应用提供数据参考和技术指导。

     

    Abstract: The efficient development of shale gas resources is crucial for the economic development and bears the important mission in achieving the “dual carbon” goals in China. Given the large water consumption of hydraulic fracturing and the irreversible pollution of strata caused by fracturing fluids, the search for a more scientific and environment friendly fracturing technology has become a hot topic in recent years. A new approach for developing shale gas using methane in-situ deflagration fracturing technology has been proposed in this study. This technology uses spark ignition to ignite methane in the reservoir and the pumped-in combustion aid to create a detonation, relying on the instant high-pressure shock generated in the reservoir rock for fracturing, enabling the reservoir to generate a complex fracture network of a certain scale without control by geostress. Its advantages lie in preventing strata pollution and reducing surface transportation costs. It is expected to become an efficient and environment friendly low-cost waterless fracturing technology. Using a methane deflagration fracturing experimental system, including independently designed fracturing devices, gas charging, ignition control, and data acquisition systems, a large-scale ground fracturing physical modeling (ϕ2.0 m×1.5 m) experiment was carried out. The pressure-time curve of the cavity pressure in the fracturing tube and the wellbore pressure were recorded and compared with the wellbore pressure and fissure characteristics of explosion fracturing and hydraulic fracturing. The results show that the peak pressure in the wellbore during the deflagration process was 495.18 MPa, 82.5 times the injection pressure. The sample had low fragmentation and a small crush area, with 7 to 9 main fractures, and the fracture width was on the centimeter scale. Methane deflagration fracturing provides ample fracturing energy, a wide impact range, and the extent of damage to the wellbore can be controlled by injection pressure. Compared to explosion fracturing and hydraulic fracturing, the technology has a longer high-pressure action time, which is more conducive to the initiation and expansion of fractures. It produces more fractures than hydraulic fracturing and longer fractures than explosion fracturing, resulting in the best fracturing effects. Experimental studies have recorded the peak pressure and pressure rise rate achieved when methane-oxygen mixtures undergo detonation at high initial pressures. This validates the feasibility of using the methane in-situ deflagration fracturing technology for shale gas development and provides data reference and technical guidance for the future practical application of the technology.

     

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