酸压中液氮伴注对裂缝内降温作用研究

摘要

采用Fluent软件模拟了酸压伴注液氮时裂缝中温度分布,分析了酸压注入过程中裂缝温度场的变化规律,并对比了液氮伴注对缝内温度场的影响.模拟结果表明,酸液注入后降温作用明显,裂缝入口比裂缝尖端温度低近50℃;液氮比(液氮与混合液体积比)越高,裂缝中温度越低,液氮比高于13%后,增加液氮比,降温作用明显减弱,对于模拟使用的条件,推荐液氮比13%;液氮伴注降温作用明显,其它条件相同时,伴注液氮能造成约15℃温度差异,因此,液氮伴注能明显增加活酸作用距离.%In this paper,temperature distribution inside the fracture in acid fracturing with fluent is simulated,and the temperature variation behavior during acid injection with liquid nitrogen is studied.The results show that acid injection has apparent cooling effect on the fracture surfaces,and the fracture tip has a temperature about 50 ℃ higher than the one at the inlet of the fracture.The higher the liquid nitrogen fraction,the lower the temperature is inside the fracture.When the ratio of nitrogen and liquid is above 13%,increasing liquid nitrogen fraction does not decrease temperature apparently.Therefore,13%of liquid nitrogen is recommended.With the same conditions,liquid nitrogen injection can cause about 15℃ difference. Therefore,acid with liquid nitrogen can increase penetration distance of live acid.