纳米聚合物微球与低矿化度水复合调驱效果评价及作用机理

Investigation on the Profile Control and Oil Displacement of Combining Nano-polymer Microspheres and Low Salinity Water Flooding

低渗透油藏注水开发过程中注入水窜逸严重,开发后期仍存在大量剩余油。聚合物微球驱和低矿化度水驱是油藏深部调驱的两种有效手段,前者侧重调剖,后者侧重驱油,两者结合有望达到兼具调剖和驱油的双重效果。通过岩心驱替实验对纳米聚合物微球与低矿化度水复合调驱效果进行评价,并利用核磁共振T_(2)谱和成像测试,揭示岩心驱油过程中不同尺寸孔隙中原油动用程度和驱油机理。结果表明,微球能够有效封堵水窜通道,改变注入流体流动方向,使低矿化度水进入中小孔隙,提高波及效率和驱油效率,且注入水矿化度越低,中小孔隙中的原油动用程度越高。提高微球浓度和降低注入流体矿化度均会增强微球封堵效果,引起注入压力增加和采收率显著提高。低矿化度水与纳米聚合物微球协同增效驱油具有提高低渗透油藏采收率的潜力。

Water injection development in low permeability reservoir generally results in serious channeling of injected water and a large amount of remaining oil.Polymer microspheres and low salinity water are proven effective approaches for profile control and oil displacement in hydrocarbon reservoirs.The former focuses on profile control while the latter favors oil displacement,and thus their combination is expected to achieve the dual effect of profile control and oil displacement.This paper evaluated the effects of simultaneously injecting nano-polymer microspheres and low salinity water via core floods.Nuclear magnetic resonance T_(2) spectrum and imaging test were used to reveal the extent of residual oil in pores of various sizes during core flooding as well as the mechanism of oil displacement.The results showed that the microspheres could eliminate water channeling and change flow direction,forcing the low salinity water to enter smaller pores and improving the sweep and oil displacement efficiency.The lower the salinity,the higher the produced oil from small and medium-sized pores.Increasing the concentration of microspheres and decreasing the salinity of injected fluid could enhance the plugging effect of microspheres,resulting in enhanced injection pressure and oil recovery.This study confirmed the potential of synergistic flooding with low salinity water and nano-polymer microspheres in improving oil recovery in low permeability reservoirs.