Synergistic Oil Displacement Effect And Mechanism Of Weak Gel-2D Intelligent Nano Black Card After Polymer Flooding

With the further research on polymer flooding and subsequent water flooding,the application of polymer flooding is expanding and the oilfield is at the high water cut stage.Whereas,the complexity of interlayer layers,pore structure and residual oil distribution and the residual polymer,how to take oil reservoir after polymer flooding method to enhance oil recovery has become a hot topic,in this paper we used a new low gel and independent research and development of new nano-materials in the laboratory and to enhance oil recovery after polymer flooding oil displacement agent.In order to study the oil displacement effect of low initial viscosity gel-nano black sheet fluid in the post-polymer flooding reservoir,the performance of the system and unvariate and binary control groups were evaluated and screened first,and the evaluation of changing wettability,rheological properties,characterization of interfacial tension reduction ability and emulsification performance were carried out.Secondly,the core displacement effect was studied by casting core,1m sand filling pipe and Beret core.The displacement effect of each system in polymer flooding reservoir was evaluated by the production degree,(residual)resistance coefficient and diversion rate of each monolayer.It is clear that the low initial viscosity gel has the characteristics of low initial viscosity,good injection performance and high gel-forming strength,which can achieve the purpose of selective plugging of target oil reservoir,and use the characteristics of "intelligent oil finding and efficient oil displacement" of flake nanomaterials to start oil in middle and low permeability layers.Experiments have shown that 0.07 PV low initial viscosity gel(0.1 wt.%)+0.7 PV nano black-card fluid(0.005 wt.%)has a good profile control and oil displacement effect;In the 2D visualization experiment,the weak gel can effectively block the water channeling channel,and the nano black-card fluid can achieve the effect of "shoveling oil" by changing the wettability and contact Angle.The dynamic oil displacement experiment showed that,compared with other combination schemes with weak gel after polymer flooding,the weak gel and nano black tank fluid scheme has the best oil displacement effect,and the recovery rate of artificial core,1m long sand filling pipe and Bailey core after polymer flooding is increased by 16.63%,16.78% and 15.08%respectively.The synergistic can realise action of deep regulation and flooding of heterogeneous reservoirs.The technology of weak gel-nanomaterial deep collaborative regulation and flooding is expected to become an integrated oil displacement system of "plugging,regulation and flooding" to achieve the goal of enhancing oil recovery after polymer flooding.