多尺度冻胶分散体的制备机理

Preparation mechanism of multiscale dispersed particle gel

常规提高采收率方法因聚合物耐剪切耐地层理化性质差、聚合物微球合成工艺复杂成本高、预交联颗粒注入性差等问题,限制了油藏适用范围。针对这一技术难题,基于地面制备的本体冻胶体系,建立了规模化高效制备多尺度冻胶分散体的工艺新方法,并探索了其制备机理。研究结果表明:制备的多尺度冻胶分散体为形状规则、粒径可控(650~5 000nm)的水相分散颗粒体系,具备低黏度,表面带负电(-20^-35 mV)的特点。本体冻胶强度、剪切速率、剪切时间和制备方式均会影响多尺度冻胶分散体的制备,其中剪切速率是制备多尺度冻胶分散体的主控因素。多尺度冻胶分散体制备包括本体冻胶的形成和多尺度冻胶分散体的剪切成形两部分,本体冻胶的形成过程包括诱导期、快速交联期、慢速增长期、稳定期4个化学交联阶段;多尺度冻胶分散体的剪切成形过程包括破碎磨圆区、颗粒进一步磨碎区、颗粒均一区3个物理剪切阶段,整个剪切过程持续3~15 min即可完成,进而实现多尺度冻胶分散体的高效制备。

Due to poor anti-shearing ability and the resistance to stratigraphic physical and chemical properties of polymer,complex synthesis method and high cost of polymer microspheres,weak injection capacity of preformed particle gel,etc.,the traditional enhanced oil recovery method is only applicable to limited reservoirs.Aiming at such a technical difficulty,the bulk gel system was prepared in gravity condition;on this basis,the new technology of multiscale dispersed particle gel(DPG)was established and achieved the large-scale efficient preparation.The preparation mechanism was explored.The research results indicate that the prepared multiscale DPG particles are aqueous phase dispersed particle system with regular shape,controllable size(650-5 000 nm),low viscosity and negative charge on surface(-20--35 mV).The bulk gel strength,shearing rate,shearing time and preparation mode can affect the preparation of multiscale DPG particle,and the shearing rate is the main controlling factor for the preparation of multiscale DPG particles.Multiscale DPG particles consist of two parts,i.e.,the formation of bulk gel and the shearing formation of multiscale DPG particles.The formation process of bulk gel is divided into four chemical cross-linking stages,i.e.,induction stage,rapid cross-linking stage,slow growth stage and stabilization stage.The shearing formation process of multiscale DPG particles includes three physical shearing stages,i.e.,broken rounded stage,further particle milling stage and particle homogeneous stage.The whole shearing process can be completed within 3-15 min,followed by efficient preparation of multiscale DPG particles.