叶功勤, 曹函, 高强, 陈裕, 孙平贺, 张绍和. 充填型单缝煤岩水力脉动解堵试验研究[J]. 工程科学学报, 2022, 44(3): 348-356. DOI: 10.13374/j.issn2095-9389.2020.10.17.001
引用本文: 叶功勤, 曹函, 高强, 陈裕, 孙平贺, 张绍和. 充填型单缝煤岩水力脉动解堵试验研究[J]. 工程科学学报, 2022, 44(3): 348-356. DOI: 10.13374/j.issn2095-9389.2020.10.17.001
YE Gong-qin, CAO Han, GAO Qiang, CHEN Yu, SUN Ping-he, ZHANG Shao-he. Experimental study of the unblocking of coalbed with single-slit filling by pulse hydraulic fracturing[J]. Chinese Journal of Engineering, 2022, 44(3): 348-356. DOI: 10.13374/j.issn2095-9389.2020.10.17.001
Citation: YE Gong-qin, CAO Han, GAO Qiang, CHEN Yu, SUN Ping-he, ZHANG Shao-he. Experimental study of the unblocking of coalbed with single-slit filling by pulse hydraulic fracturing[J]. Chinese Journal of Engineering, 2022, 44(3): 348-356. DOI: 10.13374/j.issn2095-9389.2020.10.17.001

充填型单缝煤岩水力脉动解堵试验研究

Experimental study of the unblocking of coalbed with single-slit filling by pulse hydraulic fracturing

  • 摘要: 利用室内自行研制的可调频脉动水力压裂系统及预制充填型单缝的煤岩,开展不同频率条件下水力脉动解堵试验,研究脉动作用下解堵水压演化过程和解堵效果。试验结果表明,水力脉动解堵压力演化过程可分为三个阶段:压力上升阶段、压力下降阶段和压力波动稳定阶段。在疲劳损伤和脉动波的双重作用下,脉动作用下的煤岩解堵表现出解堵压力阀值比定常流作用下更低、压降持续时间更短、压降幅值更小的特点。定常流作用下煤粉运移集中在压力下降阶段;脉动压力作用下煤粉在压力下降阶段和压力波动稳定阶段均有运移,且压力下降时间与运移煤粉总量成正相关关系,但煤粉总的运移量和定常流作用下的相当。脉动作用和定常流作用下径向渗透主要发生在压力上升至压力峰值阶段,但脉动流的解堵时间短,则滤液渗透半径小对储层的伤害小。综合考虑解堵压力、煤粉运移、解堵渗透路径和解堵渗流深度,特别是解堵压力和解堵渗流深度作为主要评价因素,在3 Hz条件下解堵效果最好,其具有较低的解堵压力和最小的解堵渗流深度。

     

    Abstract: As an unconventional natural gas resource, coalbed methane has huge reserves in China and has good prospects for exploitation. During the coalbed methane extraction process, a large amount of coal powder is produced. Coal powder accumulates in fissures and blocks them, which is one of the important factors affecting the permeability of coalbed methane. A hydraulic fracturing system with adjustable frequency pulsation and single-slit filling prefabricated samples were developed for testing coalbed fissure unblocking. Experiments were carried out to study the evolution process of the unblocking pressure and the unblocking effect of pulse action under different frequency conditions. Results show that the evolution process of the unblocking pressure can be divided into three stages: pressure rise phase, decline phase, and pressure fluctuation stability phase. Compared to that, under a steady flow, the pressure threshold under the pulse action is lower, pressure drop duration is shorter, and pressure drop amplitude is smaller. The migration of pulverized coal under the action of steady flow is concentrated in the pressure drop stage. Under the action of pulsating pressure, pulverized coal migrates in the pressure drop stage and the pressure fluctuation stable stage. The pressure drop time is positively correlated with the total amount of pulverized coal transported, but the total transport volume of pulverized coal is equivalent to that under the action of steady flow. The fluid infiltration along the radial direction mainly occurs during the pressure rise to the peak pressure. The filtrate penetration radius is smaller due to the shorter unblocking time under the pulsating flow, and the reservoir damage is small. Comprehensively considering the unblocking pressure, coal migration, unblocking seepage path, and unblocking seepage depth, especially the unblocking pressure and unblocking seepage depth, as the main evaluation factors, the best unblocking effect is under the condition of 3 Hz, which has a lower solution.

     

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