变黏度聚合物驱注入参数优化研究与应用

Study and application of injection parameters optimization for polymer flooding with variable viscosity

针对渤海油田储层非均质性强,单一段塞连续注入易发生剖面返转等问题,利用数值模拟和人造岩心三管并联物理模拟实验,对变黏度聚合物驱提高采收率机理及注入参数进行研究与优化。研究结果表明:在聚合物用量相同的情况下,高黏低速+低黏高速段塞注入为最优注入方式,6倍渗透率级差下,高低黏段塞大小比≤0.3,注入速度比在1:2时,可最大程度延缓剖面返转,实现均衡驱替,从而大幅提高采收率。在6倍渗透率级差下,高低黏段塞大小比为0.3时,高低黏段塞恒速交替注入2轮次比单一段塞提高采收率2.42%;高低黏段塞注入速度比为1:2时,高黏低速+低黏高速段塞注入比单一段塞提高采收率4.84%。现场试验增油效果明显,为渤海油田聚合物驱高效开发提供了指导。

Aiming at the problem of strong reservoir heterogeneity and profile reversal of continuous injection of a single slug in Bohai Oilfield,the EOR mechanism and injection parameters of polymer flooding with variable viscosity were studied and optimized by numerical simulation and physical simulation of three-pipe parallel artificial core.The results show that high-viscosity lowvelocity and low-viscosity high-speed slug injection is the best injection method with the same amount of polymer.At 6 times permeability difference,the profile reversion can be delayed to the greatest extent,the balanced displacement between layers can be realized,thereby greatly improving the recovery factor when the size ratio of high and low viscosity slug is≤0.3 and the injection velocity ratio is 1:2.When the size ratio of high and low viscosity slug is 0.3,the recovery of high and low viscosity multi-slug alternate injection 2 rounds at constant rate has enhanced by 2.42%compared with a single slug.When the injection velocity ratio of high and low viscosity slug is 1:2,the recovery of high viscosity low speed and low viscosity high speed slug injection has enhanced by 4.84%compared with a single slug.The field test has obvious oil-increasing effect,which provides guidance for the efficient development of polymer flooding in Bohai Oilfield.