原油黏度对稠油聚合物驱影响的实验研究

Experimental study on the effects of crude oil viscosity on polymer flooding of heavy oil

由于油藏条件、聚合物注入性以及经济性的限制,稠油聚驱允许的聚合物浓度往往难以达到报道的"最优值"。在聚合物浓度恒定或变化较小时,原油黏度增大对聚驱采收率的影响,将直接关系到聚驱在相对高黏度原油油藏的适应性。利用不同黏度的普通稠油样本,进行了大量的聚合物驱油实验,发现原油黏度对聚驱采收率的影响受聚合物使用浓度或水油黏度比的控制。在原油黏度:50~500mPa·s,水油黏度比:0.02~0.62的条件下,聚驱采收率随原油黏度的增大而减小。随聚合物浓度的增大,稠油聚驱采收率上升加快,50~500 mPa·s原油驱替用聚合物浓度应大于等于2 000 mg/L;同时,原油黏度越高,增加聚合物浓度带来的采收率增幅和经济效益越大。在并联模型中,300mPa·s原油的聚驱替效率和剖面调整效果均差于50mPa·s原油,导致其聚驱采收率低于后者。

Due to the limitation of reservoir conditions, polymer injectability and economy, it is difficult to achieve the optimal polymer concentration during polymer flooding in heavy oil reservoirs. When the polymer concentration is constant or little changed, the effect of crude oil viscosity increasing on its recovery directly determines the adaptability of polymer flooding in such reservoirs. A large number of polymer flooding tests were carried out by using the ordinary heavy oil samples with different viscosity. It’s found that the effect of crude oil viscosity on polymer flooding was controlled by polymer concentration or water/oil viscosity ratio. Under the used conditions(crude oil viscosity: 50~500 m Pa·s, the ratio of water and oil viscosity: 0.02~0.62), the oil recovery of polymer flooding decreased with increasing of crude oil viscosity, but increasing polymer concentration can effectively reduce this difference between the high viscosity oil recovery and the low viscosity oil recovery. With increasing of polymer concentration, the growth of heavy oil recovery got faster, and the adopted polymer concentration should be equal to or greater than 2 000 mg/L;Additionally, the higher the crude oil viscosity, the higher the obtained oil recovery and economic benefit brought by polymer concentration increase, finally, the higher the polymer concentration should be used for its displacement. The flooding experiments in parallel models showed that the efficiency and profile improvement during the polymer flooding of 300 mPa·s crude oil were worse than those of 50 mPa·s. As a result, a lower oil recovery occurred in the former case.