渤海稠油油田早期注聚剖面返转规律及控制方法研究

Laboratory Study of Profile Reversion in Early Stage Polymer Injection for Heavy Oil Recovery in China Bohai Bay

为了提高海上非均质稠油油田聚合物驱效果,采用疏水缔合聚合物AP-P4(特性黏数1800 m L/g、疏水基含量0.8%),通过双管并联岩心物理模拟实验研究了渗透率级差、注聚浓度、注聚时机对渤海稠油油藏早期注聚剖面返转的影响规律,比较了交替注入聚合物的类型和浓度、交替次数对提高采收率效果的影响。研究结果表明:聚合物驱适用于早期注聚(含水率小于80%)、渗透率级差小(﹤6)的油层条件,聚合物良好的注入性和合适的流度控制作用对提高稠油聚合物驱采收率十分重要;弱凝胶体系和聚合物体系交替注入对高渗层伤害大,提高采收率效果差;在相同聚合物用量条件下,高浓度(2250 mg/L×0.15 PV)与低浓度聚合物体系(1750 mg/L×0.15 PV)交替注入2个轮次比单一段塞注聚(聚合物用量1200 mg/L·PV)提高采收率4.3%,渤海稠油油藏开展高浓度/低浓度聚合物体系交替注入可改善稠油聚合物驱效果。

To improve polymer flooding results in Bohai heterogeneous heavy oil field,the dual parallel core flooding test was conducted to study effects of permeability differential,polymer concentration,water cut at polymer injection on the profile reversion,and effect of the injected polymer type and concentration,polymer alternative injection cycles on enhanced oil recovery was investigated. The results showed that polymer injection was suitable at early stage（water cut less than 80%）,small permeability differental（less than 6）,and appropriate polymer concentration for effective mobility control and good injectivity had vital importance on polymer flooding efficiency. The alternating injection of weak polymer gel and polymer solution would reduce the total recovery at the same dosage of polymer injection;alternate injection of high concentration polymer system（2250 mg/L×0.15PV）and low concentration polymer system（1750 mg/L×0.15 PV）for 2 cycles had more than 4.3% recovery efficiency than that of the direct polymer injection at the same dosage of 1200 mg/L·PV. The alternative injection of polymer slug could improve polymer flooding performance in Bohai heterogeneous heavy oil reservoir.