深水气井环空带压模型的建立与研究

ESTABLISHMENT AND RESEARCH OF ANNULAR PRESSURE MODEL FOR DEEPWATER GAS WELLS

为了研究深水气井作业生产井密闭环空压力变化规律,基于典型深水作业井井身结构,分析了密闭环空组成和特点;根据井筒压力传递特点,建立了非泄露下多套管密闭环空压力预测模型、环空气柱体积变化模型,以及泄露下环空带压数学模型;结合现场作业井进行了环空压力变化研究。研究结果表明:环空密闭压力的快速上升主要集中在生产初期,生产20h后趋于稳定,且越靠近作业管柱内部的环空,压力增大越快;对于B环空压力取得平衡所需的时间,因环空已有气柱厚度的增大而增长;B环空平衡的最终压力随着地层压力的增大而增大,但平衡时间基本稳定。研究结果为深水气井密闭环空压力变化研究、井筒的风险预防与安全控制提供了基础。

In order to study the variation law of closed-loop pressure in deep-water gas wells,the composition and character⁃istics of closed-loop pressure were analyzed based on the wellbore structure of typical deep-water wells.According to the characteristics of wellbore pressure transmission,the prediction model of multi casing closed annulus pressure and the vol⁃ume change model of annular air column without leakage,and the mathematical model of annular pressure under leakage are established.Combined with an example well,the annular pressure analysis is carried out.The results show that the rapid rise of the annulus closed-loop pressure is mainly concentrated in the early stage of production,the pressure tends to be stable af⁃ter 20 hours of production.The closer to the annulus inside the operation string,the faster the pressure increases.With the in⁃crease of the initial gas column thickness,the balanced time required for pressure in B annulus increases.The final balanced pressure of B annulus increases with the increase of formation pressure,but the balanced time is basically stable.The re⁃search results provide the basis for the study of the pressure change in the closed annulus of deepwater gas wells,the risk pre⁃vention and safety control of the wellbore.