气驱采油注气油管刺漏引发的多相运移及压力突变分析

Analysis on tubing leakage caused by gas injection with pressure mutations when multiphase transport

基于单管局部阻力损失方程,建立了气驱采油注气油管刺漏引发的压力突变模型;考虑气相的压缩性、气相的滑脱及多相流型的变化,建立了环空多相运移耦合模型;对模型编程求解,结果表明:油管刺漏初期,刺漏点发生压力突变,引起刺漏点压力突变的本质因素是气体分流量、环空与油管之间的压力差及气相的可压缩性等因素;油管刺漏中期,油管内气相窜至环空,并沿环空向井口作浮升运动,空隙率逐渐增大,在临近井口处形成气穴,由于环空压力持续增大,使刺漏量及刺漏点两侧压差持续减小;油管刺漏后期,环空带压趋于平缓,刺漏点两侧压力趋于平衡,刺漏量逐渐变为0;刺漏造成的环空压力上升迅猛,并且在泄压后压力急剧回升,对安全生产造成极大危害,应对油管定期监测和诊断,避免油管刺漏的发生。

Based on single tube local resistance loss equation,the gas-drive oil pipe leakage caused by pressure mutation model is put forwarded.By considering the compressibility of gas phase,gas phase slippage and the change of the multiphase flow pattern,an annulus multiphase migration coupling model is established.Programming to solve the model,results obtained show that,at the early stage of tubing leakage,thorn funneled pressure mutations,thorn funneled pressure mutation gas diversion quantity,the pressure differential between the annulus and the tubing and the compressibility of gas phase are the essential factors.At the middle stage of stab tubing leakage,the gas phase to the annulus,and along the float up to the wellhead annulus do sports,void fraction increases gradually,air pockets at near the top of the well,with increase of annulus pressure,on both sides of stab thorn leakage and funneled pressure differential continues to decrease.At the late stage of tubing leakage,annulus pressure flatten out,thorn funneled into balance on both sides of the pressure,thorn leakage quantity gradually becomes zero.Thorn leakage cause of annulus,rapid pressure rise,and sharp renewed pressure after pressure relief,causes great harm to the safety production.The regular monitoring and diagnosis of tubing should be conducted to avoid the occurrence of tubing puncture and leakage.