大庆油田聚合物驱后周期分质注聚合物技术

为进一步提高聚合物驱开发效果,针对不同渗透率地层,研究了不同分子量聚合物分子回旋半径与地层孔喉半径的配伍关系,结合周期注水原理,形成不同分子量聚合物溶液周期注入技术。在考虑聚合物井筒炮眼剪切降黏作用下,地层平均渗透率为35×10-3μm2时,应选用800×104分子量聚合物;平均渗透率为100×10-3μm2时,应选用1 200×104分子量聚合物;渗透率大于300×10-3μm2时,应选用2 500×104以上分子量聚合物;分质注聚合物半周期控制在约3个月为最佳。相比传统笼统注聚合物方法,周期分质注聚合物技术可以综合聚合物驱及周期注水技术,更为有效地提高石油采收率。

Cyclic injection technology of different polymer after polymer flooding in Daqing Oilfield

In order to improve the effect of polymer flooding, the compatibility between polymer molecular weight and formation pore-throat radius with different permeability was studied. Based on the cyclic water-flooding theory, the cyclic injection technology of polymers with different molecular weight was set up. In consideration of the action of shear thinning of polymer in the perforation interval of well bore, the polymer with molecular weight of 800×10⁴ should be selected when the average permeability of formation is 35×10^-3 μm². The polymer with molecular weight of 12×10⁶ should be chosen when the average permeability of formation is 100×10^-3 μm². When the average permeability of formation is over 300×10^-3 μm², the polymer with molecular weight over 25×10⁶ should be applied. The half cycle of the polymer injection should be about 3 months. Compared with the conventional polymer injection, the cyclic injection technology of polymer with different molecular weight can be combined with the polymer flooding and water flooding technologies, which can effectively enhance oil recovery.