氮气的溶解及抽提效应对原油性质的影响

氮气混相驱、非混相驱过程中由于存在氮气的溶解及抽提(蒸发)效应,使原油组分和原油的物理化学性质均发生变化.通过PVT相态实验研究表明,原油注入氮气后原油体系组成、性质变化明显,随着氮气注入比例的增加,原油的饱和压力、膨胀系数、体积系数、气油比增加,原油黏度、密度则减小;氮气溶解明显改善了原油的流动性质,增强了油藏驱动能量,有利于提高采收率.原油脱气过程中由于抽提(蒸发)效应对原油性质也有一定影响,但影响相对小一些,不会对近井地带原油生产带来明显负面影响.

Effects of nitrogen dissolution and separating-out on the property of crude oil in nitrogen displacement

In the process of the miscible or immiscible flooding of nitrogen, the physical and chemical properties and the composition of crude oil will change due to the effects of the dissolution and the separating-out of nitrogen. PVT phase behavior experiments show that, with the increase of the injected nitrogen, the saturation the pressure, the expansion coefficient, the volume factor and the gas/oil ratio of crude oil system increase, but the viscosity and the density of it decrease; the dissolution of nitrogen greatly improves the flow behavior of crude oil and increases the drive energy of oil reservoir, which is beneficial to the enhancement of crude oil recovery factor; the separating-out of nitrogen has a little unfavorable effect on the property of crude oil, but this does not produce unfavorable effect on the production of crude oil near wellbore zone.