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随着油气勘探开发不断深入,越来越多的CO_2或者高含CO_2气田被开采,考虑到CO_2物性对压力温度非常敏感,若忽略相态转变和传热影响造成井筒压力误差较大,易造成井涌、井喷等严重钻井事故,针对CO_2的物理性质并考虑其在井筒内相态变化,将井筒传热、压力与CO_2物性参数耦合迭代计算,建立了超临界CO_2侵入时井筒流动与传热的数学模型,计算结果表明:CO_2流体在环空上升过程中由超临界或者液态转化为气态,相态转变点上部为气液两相流下部为井筒拟单相流;SC-CO_2侵入对环空温度和压力均有影响,侵入速度越大,井底温度越高,但是对环空出口温度影响较小;井底压力随侵入量的增大先急剧减小后缓慢增大;随着井口回压增大,井底压力增大,但影响程度逐渐减小.
With the deepening of exploration and development of oil and gas, more and more CO_2 or high-CO_2 gas fields are mined. Considering that the physical properties of CO_2 are very sensitive to pressure and temperature, if the misalignment and heat transfer are neglected, In view of the physical properties of CO_2 and its phase change in wellbore, the wellbore heat transfer and pressure were coupled with CO_2 physical parameters iteratively to calculate the wellbore flow and heat transfer when supercritical CO_2 intruded The results show that the CO_2 fluid is transformed from supercritical or liquid state to gaseous state during the ascending of the annulus and the lower part of the phase transition point is a single-phase wellbore in the lower part of the gas-liquid two-phase flow. SC-CO_2 invading the annulus Air temperature and pressure have an impact, the greater the invasion rate, the bottomhole temperature is higher, but the impact on the annular outlet temperature is small; Bottomhole pressure increases sharply with the increase of intrusion increases slowly and slowly; With the wellhead Back pressure increases, bottomhole pressure increases, but the impact of the gradual decrease.