井下管柱渗漏导致注采气井A环空带压模拟分析研究  

Simulation and Analysis of Sustained "A"-Annulus Pressure of GasInjection-Production Wells Caused by Downhole String leakage

作　　者：赵萌 ZHAO Meng(Oil Production Technology Research Institute of Liaohe Oilfield Company,CNPC,Panjin,Liaoning 124010,China)

机构地区：[1]中国石油辽河油田公司采油工艺研究院

出　　处：《钻采工艺》2024年第5期81-87,共7页Drilling & Production Technology

基　　金：中国石油辽河油田公司重大科技专项“辽河油田储气库群注采关键技术研究”(编号:2023KJZX-07)。

摘　　要：注采气井存在井下管柱渗漏导致A环空带压的现象,影响日常正常运行,测井工具可定位井下管柱漏点位置,但操作繁琐、成本高,有必要开展基于数值模拟的漏点参数诊断研究,定量化剖析环空带压规律。将A环空带压过程划分为气体渗漏、“气泡”膨胀、气柱聚并三个阶段,采用微元分析的思想,基于压力平衡、气液体积耦合等理论,创新建立了“气泡”膨胀阶段的数学模型。结合小孔模型形成A环空带压模拟方法,编制形成注采气井A环空带压计算模拟分析软件,通过参数假设、拟合对比可反向确定渗漏点的数量、深度、当量直径等参数。同时对渗漏点参数进行敏感性分析,研究表明渗漏点深度主要影响A环空的稳定带压值,渗漏点数量与当量直径主要影响A环空压力变化速率。现场注采气井实际运行中,若井下管柱在浅部产生多个大尺寸的渗漏点,A环空会快速产生较大的井口压力,应优先处理最上部渗漏点,避免环空压力过大导致井屏障失效。该研究为注采气井的管柱完整性评价提供了新的技术手段。Gas injection-production wells has the phenomenon that the leakage of downhole string leads to sustained"A"-annulus pressure,which affected the daily normal operation.Logging tools can locate the leakage point of downhole string,but the operation is cumbersome and costly.It is necessary to conduct research on leak point parameter diagnosis based on numerical simulation,and quantitatively analyze the law of pressure in the annulus.The process of sustained"A"-annulus pressure caused by pipe string leakage is divided into three stages:gas leakage,"bubble"expansion,and gas column coalescence.Adopting the concept of elemental analysis,based on the theory of pressure balance and gas-liquid volume coupling,the mathematical model of"bubble"expansion is innovatively established.Combining the small hole model to form a simulation method for sustained"A"-annulus pressure,a software for calculating and analyzing the pressure in the A annulus of injection and production gas wells was developed.The number,depth and equivalent diameter of leakage points can be determined in reverse through parameter assumptions and fitting comparisons.The sensitivity analysis of the leakage point parameters is carried out.The research shows that the depth of leakage point mainly affects the stable pressure value of the A annulus,while the number and equivalent diameter of leakage points mainly affect the rate of pressure change in the A annulus.In the actual operation of gas injection-production wells,if multiple large-sized leakage points are generated in the shallow part of the downhole string,it would quickly generate high wellhead pressure in A annulus.The top leakage point should be prioritized to avoid the failure of the well barrier due to excessive annulus pressure.This study provides a new technical means for evaluating the integrity of tubing in gas injection-production wells.

关 键 词：注采气井 管柱渗漏 A环空带压 数学模型 井屏障 

分 类 号：TE28[石油与天然气工程—油气井工程]