注液态CO_2采油井筒热力分析

目前CO2已经被用作有效的驱油剂,CO2到达井底时的热力状态对驱油效果有较大影响.针对影响井底CO2压力和温度的因素,根据液态CO2在竖直井筒中的热量传递原理和流体流动理论,在Ramey建立的物理模型基础上,建立了液态CO2井筒流动与传热数学模型,通过求解实例,得到井筒内液态CO2温度和压力的分布规律以及各因素对井底CO2参数的影响.结果表明:井筒内CO2的温度和压力随井深的增加而近似成线性增加;当注入速率增大时,气液分界面加深;井底温度随入口流量的增加而降低,而受入口温度的影响较小;井底压力随井口注入压力的增加而成比例增加,随着流量的增加呈先增后减的趋势;环空介质采用清水比空气的导热效果好.

Thermodynamic analysis of the liquid carbon dioxide in wellbore in the process of carbon dioxide displacement

Carbon dioxide is used as an oil displacement agent,and its thermodynamic state at the bottom of the wellbore has great influence on the oil displacement result.Based on Ramey's model,the mathematical model of the flow and heat transfer of the liquid carbon dioxide in wellbore is established according to the analysis of the factors of influencing the temperature and the pressure of the carbon dioxide at the bottom of wellbore,and the distribution laws of the temperature and the pressure of the liquid carbon dioxide in wellbore are obtained.The influence laws of the factors on the temperature and the pressure are analyzed,and it is shown that the temperature and the pressure will linearly increase with the increase of well depth; the gas-liquid interface will drop with the increase of injection flow rate; the well-bottle temperature will drop with the increase of the well-head flow rate,and the well-head temperature has a little influence on the well-bottle temperature; the well-bottle pressure will linearly increase with the well-head injection pressure,and it will increase firstly and then decrease with the increase of the well-head flow rate.Water has better heat conduction result than air in annular space.