煤层气自激振荡增产工具空化试验

为提高煤层气采收率,对煤层气自激振荡增产所用空化工具的内部结构进行了室内试验研究,得到了不同流量、孔径和进出口锥度下的节流压差,计算得出各结构及试验条件对应的空化数,进而反映各因素对空化效果的影响。研究结果表明:流量和孔径是影响空化的主要因素,流量与压差成正比,孔径与压差成反比,为了更容易产生空化,应减小孔径,增大流量;流量较小时空化数增加速率大于流量较大时空化数增加速率,孔板直径越小,空化效果越好;流量较大时,孔板直径对空化效果影响不大;采用一次节流(上结构)入口锥度1∶1、出口锥度1∶0.5以及二次节流(下结构)入口锥度1∶0.5,此时空化效果达到最优。研究结果对于煤层气井的增产技术研究具有一定的指导意义。

Experimental on Cavitation of Self-Oscillation Tool for Coalbed Methane

To enhance the recovery of coalbed methane,experimental study was conducted on the internal structure of the cavitation tool used for self-oscillation stimulation of coalbed methane. The choke pressure differences under different flow rates,aperture diameters and inlet and outlet tapers were obtained. The cavitation numbers corresponding to each structure and various experiment conditions were obtained,which reflect the impact of factors on the cavitation effect. The results showed that flow rate and aperture are the main factors affecting cavitation. The flow rate is proportional to the pressure difference,while the aperture is inversely proportional to the pressure difference. To generate cavitation more easily,the aperture should be reduced and the flow rate should be increased. The increase rate of the cavitation number is relatively high when the flow rate is small. Smaller diameter of the aperture results in better cavitation effect. When the flow rate is large,the aperture diameter has little effect on the cavitation effect. Under the first choke( the upper structure) inlet taper of 1 ∶ 1 and the outlet taper of 1. 0 ∶0. 5,and the secondary choke( the lower structure) inlet taper of 1 ∶ 0. 5,the cavitation effect is the best. The study could provide some guidance for the researches on the stimulation technology of coalbed methane wells.