摘要
深层气井开发过程中存在油管柱泄漏失效导致的油套环空异常带压现象,易造成气体泄漏、井口顶升和管柱损坏等事故,威胁井筒安全。与传统井下测井方法相比,采用地面诊断技术可快速判断油管泄漏程度,精准定位井下泄漏点,避免生产管柱扰动,实现对井筒潜在风险的“早发现,早识别”。首先根据压力平衡原理建立泄漏点深度求解模型,其次采用小孔模型描述气体泄漏过程,构建基于环空体积相容性原则的气体聚集增压模型,应用控制变量法对环空带压敏感性因素进行定量分析,并根据泄漏点深度和当量尺寸差异,结合环空泄压恢复测试曲线特征,将油套环空起压规律划分为4类典型模式。以案例井参数为例,油管柱泄漏失效条件下引发的油套环空带压按物理过程划分为管柱小孔泄漏、气液两相运移和气穴聚集增压3个阶段,随着时间推移,油套环空压力和气体体积逐步上升,泄漏速率逐渐降低,直至泄漏点内外侧压力平衡时趋于稳定,其中“浅部大孔、高压快升”的起压模型风险等级最高;经过反演计算,案例井油套环空压力值26.1 MPa,泄漏点当量尺寸2.1 mm,最大泄漏速率0.20 m3/min,井筒安全风险相对较高,建议采用机械修补、化学堵剂等方式进行密封堵漏。
In the development process of deep gas well,the phenomenon of abnormal tubing-casing annulus pressure is caused by tubing string leakage and failure,which is likely to lead to gas leakage,wellhead jack-up,string damage and other accidents and consequently threaten wellbore safety.Superior to the traditional downhole logging method,the surface diagnosis technology can judge the tubing leakage degree rapidly,locate downhole leakage points accurately,avoid the disturbance of production string and discover and identify potential wellbore risks as early as possible.Firstly,the leakage point depth calculation model was established according to pressure balance principle.Then,the process of gas leakage was described by means of pinhole model,and the gas accumulation and pressurization model based on the annulus volume compatibility principle was constructed.Finally,the sensitivity factors of annulus pressure were quantitatively analyzed by means of control variable method.In addition,the annulus pressure increase laws were divided into four typical modes based on leakage point depth and equivalent size difference,combined with the characteristics of annulus pressure relief/recovery testing curve.Taking the parameters of one case well as the example,the physical process of the annulus pressure caused by tubing string leakage and failure is divided into three stages,i.e.,pinhole leakage of pipe string,gas-liquid two-phase migration and cavitation accumulation and pressurization.As the time goes,annulus pressure and gas volume increase gradually and leakage rate decreases gradually until the pressure balance period inside and outside the leakage point approaches to the stable value.The pressure increase model of“large hole in the shallow part and fast rising at high pressure”is the highest in risk level.The inversion calculation results show that the annulus pressure of the case well is 26.1 MPa,the equivalent size of leakage point is 2.1 mm and the maximum leakage rate is 0.20 m3/min,indicating higher wellbore safety
作者
胡志强
路保平
侯绪田
杨进
杨顺辉
何汉平
HU Zhiqiang;LU Baoping;HOU Xutian;YANG Jin;YANG Shunhui;HE Hanping(SINOPEC Research Institute of Petroleum Engineering,Beijing 100101,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 100101,China;College of Safety and Ocean Engineering,China University of Petroleum(Beijing),Beijing 102249,China)
出处
《石油钻采工艺》
CAS
北大核心
2020年第5期632-636,共5页
Oil Drilling & Production Technology
基金
中国博士后科学基金项目“高温高压气井油套环空带压泄露点关键参数地面诊断技术研究”(编号:2020M670584)
国家科技重大专项“海上油气田关键工程技术”(编号:2016ZX05033-004)
中国石化科技攻关项目“哈萨克斯坦项目生产井井筒泄漏检测与治理技术”(编号:P20072-3)
中国石化科技攻关项目“尼日利亚、喀麦隆复杂地层钻井关键技术研究”(编号:PE19009-1)。
关键词
深层
气井
井筒安全
环空压力
泄漏参数
诊断技术
起压模式
井筒完整性
deep layer
gas well
well safety
annulus pressure
leakage parameter
pressure increase mode
well integrity
