渤海油田氮气泡沫与水交替注入提高采收率室内实验研究

Recovery experiments and application of nitrogen foam-alternating-water process in Bohai oilfields

针对渤海油田层内非均质性严重及受海上作业条件的限制,在物理模拟实验研究的基础上提出采用氮气泡沫与水交替注入方式实现对老油田的挖潜控水。氮气泡沫与水交替注入实验结果表明,在累积注入泡沫体积相同(1倍孔隙体积)以及注水体积相同(3倍孔隙体积)的条件下,改变氮气泡沫的段塞大小和注入轮次,泡沫段塞分别为1,0.5和0.33倍孔隙体积时,泡沫驱的总采收率分别为5.2%,8.01%和12.92%;泡沫驱后水驱的总采收率分别为12.89%,14.69%和17.35%;综合采收率分别为47.73%,50.33%和60%;最终采收率较初期水驱采收率分别提高了20.08%,23.53%和31.68%。通过实验发现泡沫段塞越小,采用段塞式交替注入的效果越好;且段塞越多,提高采收率的效果越明显。当累积注入泡沫体积为1倍孔隙体积时,注入轮次越多,泡沫驱累积采收率及后续水驱采收率越高,且泡沫段塞驱油的采收率随着注入轮次的增加而升高。

Nitrogen foam-alternating-water process is proposed as a potential tapping technology restricted by severe heterogeneity and special operational conditions in Bohai oilfields.As indicated in the experiments,the oil recovery in the foam injection process or following water flooding shows an increasing trend with the decrement of foam slug and the increment of injection rounds,that is,with the total foam volume and water injected,the total oil recovery during the foam-slug injection in three experiments is 5.2%,8.01% and 12.92% respectively,and 12.89%,14.69% and 17.35% respectively during the successive water-slug injection.Moreover,the oil recovery in each foam slug increases with the injection rounds,and the total oil recovery is 47.73%,50.33% and 60%,the increment reaches 20.08%,23.53% and 31.68%.