低渗非均质油藏CO2驱特征及水动力学封窜方法

CO2 flooding characteristics and hydrodynamic suppression channeling method in low permeability heterogeneous reservoirs

CO2注入油藏不仅可以大幅度提高原油采收率,且可以实现温室气体减排的目标。因此,CO2驱技术得到越来越广泛的应用。我国油藏多属于陆相沉积,非均质严重,导致CO2气窜严重,使CO2驱油效果变差。利用层内非均质模型,开展了连续注气、水气交替、间歇注气和脉冲注入CO2开采模拟实验,研究了非均质油藏CO2驱开采驱特征及动力学环境对CO2气窜的影响。实验结果表明:水气交替注入驱油效果最好,间歇注气和连续注气效果次之,脉冲注气效果最差;CO2驱未见气和低气油比阶段采出程度高,是主要的生产阶段,延长两个阶段的生产时间可以提高开发效果;通过改变水动力学条件可以有效地抑制CO2气窜,水气交替注入抑制气窜能力较强,而脉冲注气的扰动效应加剧了模型中CO2气窜,上述实验结果表明非均质油藏水气交替注入是CO2驱最优注入方式。

CO2 injection is a commonly used technique for recovering oil from mature reservoirs as it can not only greatly improve oil recovery, but also achieve the goal of greenhouse gas emission reduction. Most of the reservoirs in China are continental depos. its, and the serious heterogeneity leads to serious CO2 gas channeling, which makes the effect of CO2 flooding worse. In this paper, the simulation experiment of continuous gas injection, WAG, intermittent gas injection and pulse injection of CO2 is carried out by using the heterogeneous model in the layer, and the effects of the characteristics of the CO2 flooding in the heterogeneous oil reser. voir and the dynamic environment on the CO2 gas blow-by are studied. The experimental results show that WAG injection flooding is the best, the effect of intermittent gas injection and continuous gas injection is second, and the pulse gas injection effect is the worst;CO2 flooding has no gas and low gas oil. In the production stage, extending the production time of the two stages can improve the development effect;by changing the hydrodynamic conditions, the CO2 gas channeling can be effectively suppressed, and the WAG injection is more capable of suppressing the gas channeling, and the disturbance effect of the pulse gas injection is intensi. fied. The above experimental results show that WAG injection in heterogeneous reservoirs is the optimal injection mode for CO2 flooding.