油套环空带压气井漏点位置放压诊断研究

Study on the Pressure Relief Diagnosis of Leakage Location in Gas Well with Sustained Production Casing Pressure

高压含硫气井中天然气通过完井管柱渗入油套环空的情况较常见,环空压力超过额定承压能力时,气井将面临较大泄漏风险。漏点位置是适当控制油套环空压力、制定处理措施的重要参考数据。下入漏点检测仪器可确定漏点位置,但是影响生产,费用高,目前应用较少,因此有必要研究漏点位置地面放压诊断方法。基于多相流原理,首先研究了油套环空带压的原因与过程,提出了3类带压原因及其特点,5个气体窜入环空的过程与带压特征,然后针对完井管柱渗漏引起的油套环空带压,依据长时间渗漏后达到压力平衡的原理,建立起压力平衡模型,在此基础上依托多相流计算形成漏点位置计算方法。将油套环空放压测试与漏点位置计算方法相结合,进一步形成漏点位置放压诊断方法,并开展现场应用,确定了漏点大致位置,对油套环空带压气井的生产管理提出了有效建议。形成的漏点位置放压诊断方法为简便有效地粗略确定漏点位置提供了途径,对气井的生产管理和措施制定具有重要作用。

It is common for natural gas to penetrate into annulus of production casing through completion stringing in high pressure sour gas wells.When annulus pressure exceeds the bearing capacity,gas wells will face a great risk of leakage.The location of leakage point is an important reference data for controlling production casing pressure properly and treatment measures.The leakage point can be located by running leakage point detecting instrument,but it will affect the production and with high cost,so it is seldom used presently.Therefore,it is necessary to study the ground pressure relief diagnosis method for locating the leakage point.Based on the principle of multiphase flow,the reason and process of production casing pressure are studied firstly.Three kinds of reasons and characteristics of annular pressure are put forward,and five stages and their characteristics of gas flowing into annulus are also put forward.According to principle of pressure balance after a long time of leaking,a pressure balance model is established,on the basis of which a multi-phase flow calculation method is used to calculate the location of leakage point.By combining annulus pressure relief test and calculation method of leakage point location,the diagnosis method of leakage point location is further formed,and application is carried out to determine the approximate location of leakage point,and effective suggestions are put forward for production management of wells with annulus pressure.The method provides a simple and effective way to determine location of leakage point,and plays an important role in production management and treatment measures.