CO_2吞吐期间井筒及油层温度场及其对CO_2吞吐效果的影响

Temperature Distribution in Pay Zones during Cyclic Injection of Liquefied CO_2, and Effects on Oil Increment of CO_2 Huff-puff

研究了注入低温液态CO2过程中传热计算,包括井筒传热及温度场计算、注入期间油层温度场计算及焖井期间油层温度场计算,得到油层温度场的时间和空间分布。提出了CO2吞吐增油效果取决于CO2的溶解降粘与降温增粘的综合作用的观点。根据不同油藏条件及工艺参数,指出油层中温度分布可能出现4种不同温度-粘度带情况(4个模型)。解释了增油效果与注入量不是线性关系的原因。为选井、优化注入参数、提高CO2吞吐效果,指明了方向。

The process of heat transfer and temperature distribu tion during the injection of cold, liquefied CO_2 is studied: i.e. 1) calculati on s of heat transfer and temperature distribution around the wellbore; 2) calculat ions of heat transfer and temperature distribution in payzones during injection and soak period. The calculation results show that pay zone temperature decrease d during the CO_2 injection, and thereby, the oil viscosity increased somehow. By ananlysising field trial results, it shows that the effect of oil increment is depending on the degree of oil viscosity decreasing by CO_2 solution, and of oi l viscosity increasing by the temperature decreasing. According to the reservoir c onditions and operation parameters, four models of temperature-viscosity distri b ution are setup. By applying the model, it is clearly explained that why the oil increment is not linearly proportional to the CO_2 amount injected.