考虑井筒热效应的气体井底压力计算

Calculation of bottom-hole pressure of gas well considering thermal effect of wellbore

将井筒热效应考虑成一维热对流,将地层简化成热传导,使用Ramey定义的综合换热系数将井筒温度与地层温度联系起来,从而建立温度方程,通过解析求解得到温度变化函数.由气体状态方程将温度与压力联系起来,得到由于温度变化而产生的附加压力,将这一附加压力通过内边界条件加入到气体渗流方程中,最终得到考虑井筒热效应的井底压力表达式.比较了考虑热效应与不考虑热效应井底压力的不同,并使用某油田一个实例验证了考虑热效应时井底压力表达式的正确性.

Considering the thermal effect of wellbore as one-dimensional thermal convection,and the thermal effect of formation was simplified as heat conduction.Ramey＇s definition of comprehensive heat transfer coefficient was used to link wellbore temperature with formation temperature,so that temperature equation could be established and temperature distribution function could be solved.Variation of temperature yielded additional pressure according to the gas equation of state which linked the temperature with the pressure.The expression of bottom-hole pressure considering thermal effect of wellbore was obtained by adding the additional pressure to the internal boundary conditions of the seepage flow equation.Different cases of bottom-hole pressures considering and not considering thermal effect were compared,and an experiment in an oilfield was used to verify the expression of bottom-hole pressure considering thermal effect.