海洋凝析气井关井井筒温度与压力的计算

Calculations of shut-in wellbore temperature and pressure for offshore condensate gas wells

凝析气井关井井筒温度分布模型属于非稳态传热问题,在压力恢复关井测试中,井筒温度分布对井底压力起着重要影响。考虑流体相变和海水段传热的影响,建立了海洋凝析气井井筒气体瞬变流动的非稳态传热温度、压力耦合的数学模型,采用解析解和数值解相结合的求解方法,实际计算时先将井筒分为若干微元段,求出该段温度,然后通过非稳态传热温度、压力耦合的分布模型再计算得到该段压力,再依次计算下一微元段的温度和压力,直到计算到井底。通过对海上某气田实例气井关井过程温度、压力分布的计算,结果表明所建立的模型能有效地对压力恢复测试过程中气井井口压力进行校正。

The shut-in wellbore temperature distribution model for a condensate gas well is related to the non-steady-state heat transfer.During the buildup tests,the distribution of the wellbore temperature shows a significant impact on the bottomhole pressure.With the phase transition and seawater heat transfer taken into account,the mathematical models of non-steady heat transfer temperature and pressure coupling are established for offshore condensate gas wells.The analytic and numerical methods are combined to obtain the solutions.In practice,the wellbore is first divided into several infinitesimal segments.The temperature on one segment is then calculated and the pressure for this segment is thus calculated by the above-mentioned distribution models,with which,the temperature and pressure for the next segment is also calculated.This process is repeated until the calculation comes to the bottomhole.A case study was conducted in an offshore well and the calculation results show that these established models can effectively adjust the well-head pressure of a gas well during its buildup test.