脉冲冲击波有效作用距离影响因素模拟分析

利用数值模拟方法,分析储能、作业次数、弹性模量、地应力对重复脉冲冲击波有效作用效果的影响。结果表明:低储能时无法致裂储层,以解堵为主,高储能时可以使储层产生微裂缝提高渗透率;随着作业次数的增加,冲击波有效作用距离不断增加至最大值,此后再增加作业次数,有效作用距离基本不变;地应力对有效作用距离影响比较明显,随着地应力的增加,有效作用距离呈对数规律减小;在地应力较小、弹性模量较大时,随着作业次数增加有效作用距离增大,但试验表明作业次数增加会使储层软化,减小弹性模量,降低冲击波作业效果;当地应力较大时,弹性模量和作业次数对有效作用距离基本无影响,因此重复强冲击波对弹性模量大、地应力小的储层解堵、增产、增注效果较好,且存在一个合理的冲击波作业次数。实际应用时应根据储层参数选井,优化冲击波作业参数。

Numerical simulation study on parameters impacting effective influence distance of pulse shock waves for well stimulation

Numerical simulation was conducted to analyze the influence of energy storage, operation frequency, elastic modulus, and stress in rocks on effective repeated pulse shock waves for well stimulation. The simulation results show that, in the case with low energy storage, only plug removal can be achieved with no reservoir fracturing, while in the case with high energy storage, micro fractures can be generated that can induce reservoir fracturing and increase the formation permeability. With the increase of the number of operations, the effective influence distance of the shock wave can be increased continuously to a maximum value. After that, it remains constant. The rock stress has a great effect on the performance of the shock wave. With the increase of the rock stress, the effective distance of the shock wave decreases logarithmically, and when the rock stress is low and the elastic modulus is high, the effective distance increases as the number of operations increases. When the rock stress is high, the operation frequency and elastic modulus have little effect on the effective distance. The repeated strong shock wave can enhance plugging removal and increase production or injection of wells for the reservoir with large elastic modulus and low rock stress. In practical applications, the operation frequency can be optimized based on specific reservoir conditions.