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对高温高压气井,井筒流体高速开采过程中产生的井口热应力和环空热膨胀压力会导致井口装置抬升,破坏气井井筒完整性。本文建立了环空热膨胀压力和井口抬升计算模型,结合某高温高压气井进行了实例分析。结果表明:环空热膨胀压力随着环空温差和流体热膨胀系数的增加呈线性增加,随环空流体等温压缩系数的增加呈线性减小;C环空热膨胀压力产生的井口热应力最大,A环空最小;单层套管存在自由段时,井口抬升随着环空热膨胀压力的增加呈非线性增加,当自由段长度相同时,井口抬升对C环空热膨胀压力最敏感;多层套管同时存在自由段时,环空热膨胀压力不会改变多层套管自由段长度对井口抬升高度的影响规律,但会导致井口抬升高度增大。
For high temperature and pressure gas wells, the well head thermal stress and annulus thermal expansion pressure generated in the wellbore fluid high-speed mining process can cause the wellhead device to be lifted and the wellbore integrity of the gas well destroyed. In this paper, the calculation model of annular thermal expansion pressure and wellhead lift was established, and a case analysis was carried out with a high temperature and pressure gas well. The results show that the annular thermal expansion pressure increases linearly with the increase of annular temperature difference and fluid thermal expansion coefficient, and decreases linearly with the isothermal compression coefficient of the annular fluid. The thermal stress of the wellhead produced by C-ring thermal expansion pressure is the largest, When the length of the free section is the same, the lift of the wellhead is the most sensitive to the C-ring thermal expansion pressure; the multi-layer casing at the same time In the presence of a free section, the annular thermal expansion pressure will not change the rule of the height of the well head lifting due to the length of the free section of the multi-layered casing, but will increase the height of the wellhead lift.