摘要
超深气井温压条件苛刻、流体分布复杂,油管柱泄漏后油套环空压力大且起压机理不清,严重影响超深气井的长期安全平稳生产。为揭示油套环空在复杂泄漏工况下的起压机理,建立了基于泄漏驱动、泄漏过程和气液分布的环空压力机理模型,对油套环空起压关键参数开展了对比分析,表征了环空压力、环空液面和环空气体聚集量等关键指标的变化规律。研究结果表明:超深气井油管柱泄漏存在气体泄漏和液体泄漏2种类型以及5种泄漏工况;气体泄漏情况下,上部泄漏点决定了环空压力的最大值、环空液面最终深度和气体聚集量,泄漏点的增多会提高压力的上升速率,压力上升过程可分为全部泄漏点泄漏、部分泄漏点泄漏和泄漏完全停止3个阶段;液体泄漏情况下,环空液面持续下降,为环空气体提供更多的聚集空间,增加了环空气体聚集量,此时气体积聚所引发的风险最大;不同泄漏工况下环空压力与环空液面高度的表征具有一定的相似性,因此基于U型管理论的泄漏点定位方法不适用于多泄漏点的复杂工况,需要进一步研究新的泄漏识别检测方法。研究结果可为超深气井油套环空压力的分析与管控提供依据。
In ultradeep gas wells with harsh temperature and pressure conditions and complex fluid distribution,the pressure generation in the tubing-casing annulus due to leakage of tubing string is unclear in mechanism and high in value,which impedes the long-term safe and stable production of wells.To reveal the mechanism of pressure generation in the tubing-casing annulus due to leakage of tubing string,an annulus pressure model was built based on leakage drive,leakage process and gas-liquid distribution.Then,the model was used to conduct comparative analysis on the key parameters of pressure generation in the tubing-casing annulus.Finally,the variations of key indicators such as annulus pressure,annulus liquid level and annulus gas accumulation volume were characterized.The results show that two types of leakage(gas leakage and liquid leakage)may occur in tubing string in ultradeep gas wells,mainly under five leakage conditions.In case of gas leakage,the upper leakage point determines the maximum annulus pressure,the ultimate annulus liquid level and the gas accumulation volume.The increase in leakage points accelerates the rate of pressure rise.The pressure rise process is divided into three stages:leakage at all leakage points,leakage at partial leakage points,and stop of leakage.In case of liquid leakage,the annulus liquid level continues to drop,providing more accumulation space for the annulus gas,and increasing the annulus gas accumulation volume.At this time,the risk caused by gas accumulation is the greatest.Under different leakage conditions,the characterization of annulus pressure and annulus liquid level has certain similarities.Therefore,the leakage point localization method based on U tube theory is not suitable for the complex condition with multiple leakage points,and a new leakage detection method is required.The research results provide reference for the analysis and control of tubing-casing annulus pressure in ultradeep gas wells.
作者
曹立虎
孙金声
张波
Cao Lihu;Sun Jinsheng;Zhang Bo(School of Petroleum Engineering,China University of Petroleum(East China);PetroChina Tarim Oilfield Company;CNPC Engineering Technology R&D Company Limited;College of Mechanical and Electrical Engineering,Beijing University of Chemical Technology)
出处
《石油机械》
北大核心
2024年第11期91-98,共8页
China Petroleum Machinery
基金
国家自然科学基金委员会基础科学中心项目“超深特深层油气钻采流动调控”(52288101)
中国石油天然气股份有限公司油气和新能源分公司科技项目“三高井完整性风险量化评价技术研究与现场试验”(2022KT1904)。
关键词
超深气井
油套环空
起压机理
复杂泄漏
环空压力
ultradeep gas well
tubing-casing annulus
pressure generating mechanism
complex leakage
annulus pressure
