电热化学聚能冲击波致裂储层数值模拟及破岩规律研究

Numerical Simulation and Rock Breaking Law of Reservoir Induced by Electrothermal Chemical Energy-Gathered Shock Wave

  • 摘要: 为探究电热化学聚能冲击波储层改造技术的破岩规律及机理,首先,在明确技术装置演变的基础上,分析了聚能冲击波在储层中传播破坏的机制;然后,利用脆性材料动态破坏JH−2数值模型模拟,在物理模拟试验检验模拟方法的基础上,开展了聚能冲击波重复冲击破岩试验,分析了不同聚能冲击波波形对破岩效果的影响规律及机理;最后,对不同组合冲击波波形进行了模拟优选。研究表明:聚能冲击波破坏岩石过程包括近井破碎缓冲阶段、多裂缝竞争性起裂扩展阶段、优势裂缝延伸扩展阶段;峰值压力90 MPa、脉宽15 μs的冲击波具有较好的致裂效果;“低峰值压力+小脉宽”冲击和“高峰值压力+大脉宽”冲击组合重复冲击的破岩效果较好,产生裂缝数量多且裂缝区长度大、破碎区长度小。研究结果在一定程度上明确了电热化学聚能冲击波储层改造技术的破岩机理,为现场应用提供了理论支撑。

     

    Abstract: To explore the rock breaking law and mechanism of the reservoir stimulation technology by electrothermal chemical energy-gathered shock wave, a group of work have been done. Firstly, based on a clear understanding of the evolution of technological devices, the mechanism of propagation and damage of energy-gathered shock waves in reservoirs was analyzed. Then, by using the JH−2 numerical model of brittle material with dynamic failure and conducting physical simulation tests to verify the simulation method, the repeated impact rock breaking test of the energy-gathered shock wave was carried out, and the influence law and mechanism of different energy-gathered shock wave waveforms on the rock breaking effect were analyzed. Finally, the waveforms of different combinations of shock waves were simulated and optimized. The results indicate that the process of rock breaking by energy-gathered shock waves includes the near wellbore fragmentation buffering stage, the competitive initiation and expansion stage of multiple fractures, and the extension and expansion stage of dominant fractures. The combination of shock wave parameters with a peak pressure of 90 MPa and a pulse width of 15 μs has a good fracturing effect. The combinations of low peak pressure with small pulse width and high peak pressure with large pulse width have a better effect on repeated impact rock breaking, which produces a large number of fractures with long lengths and smaller fracture zones. The research results have clarified the rock breaking mechanism of the reservoir stimulation technology by electrothermal chemical energy-gathered shock waves to some extent, providing theoretical support for field applications.

     

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