泡沫举升排酸过程井筒压力温度数学模型研究

泡沫流体举升排酸工艺能有效排出酸化后地层的残酸，根据质量守恒方程、动量守恒方程和能量守恒方程，考虑环空泡沫流体与油管泡沫流体及地层之间的双重热传导作用，建立了泡沫流体在井筒内流动的温度分布和压力分布的数学模型，并给出了相应的边界条件和约束条件，该模型可以用于泡沫举升排酸的参数设计。利用数值方法进行了压力场和温度场的耦合求解，得到了泡沫流体温度、压力、密度在油管和环空内的分布。计算结果表明，随着井深的增加，泡沫温度、压力和密度都是增加的，泡沫举升排酸比氮气举升排酸启动压力和平衡压力都要小，随着酸排量的增加，循环点深度、启动压力和平衡压力逐渐增大。

MATHEMATICAL MODEL OF TEMPERATURE AND PRESSURE DISTRIBUTION IN WELLBORE DURING FOAM FLUID LIFT ACID DRAINAGE

Foam fluid lift can effectively drain the residual acid in acidizing treatment wells.According to energy conservation equation，mass conservation equation and momentum conservation equation，an array of ordinary differential equation for calculating the temperature and pressure distributions of foam fluid in the wellbore is established in consideration of the heat exchange between the foam fluid in the annular space and the injected fluid from tube.Boundary and limited conditions are provided.Coupled solve of temperature and pressure distributions by using numerical method is conducted.Distribution of foam temperature，foam quality and pressure in wellbore is obtained.The results show that as the increase of well depth，foam pressure and foam density increase.Threshold pressure and balance pressure of foam fluid lift are both lower than that of nitrogen gas lift.As the increase of acid flow，the depth of circle point，threshold pressure and balance pressure are all increasing.