摘要
气窜引起的高压气井套管环空压力严重影响气井的安全生产。基于对含微裂隙水泥环结构特征和高压气体渗流过程的分析,用水泥环综合渗透率和一维不稳定渗流来描述高压气体的窜流过程,根据质量守恒定律和体积相容性原则,建立了气体侵入状态下含液密闭环空压力计算模型,并用该模型研究了各个因素对环空压力的影响。环空压力的上升过程分为快速上升期和平稳上升期,环空压力的影响因素有环空液体的气体溶解度和可压缩性、水泥返高、水泥环综合渗透率以及环空体积。环空压力的上升速度随环空液体可压缩性的提高而降低;环空压力的极限值和上升速度随着水泥返高的增加而增大;水泥环综合渗透率越大,环空压力上升速度越快;环空体积的增加能够有效延长压力上升时间。从工程角度,高压气井应合理配置环空液体的可压缩性,全井段固井的高压气井应采用自修复水泥以提高固井质量,如有必要应采取相应的措施来降低水泥环的综合渗透率,同时适当增加环空体积。
The sustained annular pressure caused by channeling threatens the casing safety significantly. Cement mantle composite permeability and one-dimension unstable seepage were used to describe the channeling of high pressure gas based on the analysis of the structure of the cement mantle containing micro-fractures and the seepage process of high pressure gas. According to the mass conservation law and volume accordance principle, a model was built to predict and analyze the pressure rising process when gas invades into the trapped annulus, and then this model was used to study the impacts of different factors on the annular pressure. The pressure rising process can be divided into rapid rising stage and stable rising stage, and the factors affecting annular pressure include the gas solubility and compressibility of annular liquid, height of cement return, composite permeability of cement mantle and annular volume; the rising velocity of annular pressure declines with the increase of annular liquid compressibility; the ultimate value and rising velocity of annular pressure increase with the increase of cement return height; the higher the composite permeability of the cement mantle, the faster the annular pressure increase; the increase of annular volume can prolong the rising time of pressure. From the viewpoint of engineering, high pressure gas wells should take annular liquid with proper compressibility, self-repairing cement should be used in high pressure gas wells cemented whole to improve cement quality, the composite permeability of cement mantle should be reduced by using proper measures if necessary, and annulus volume is properly increased to prevent the pressure from rising up too quickly.
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2015年第4期518-522,共5页
Petroleum Exploration and Development
基金
国家科技重大专项"西部山前复杂地层安全快速钻井技术"(2011ZX05021-001)
教育部长江学者创新团队"海洋油气井钻完井理论与工程"(IRT1086)
关键词
高压气井
环空压力
气体窜流通道
压力上升速度
压力控制措施
high pressure gas well
channeling passageway
pressure rising velocity
annular pressure prediction
pressure control measures
