Optimization And Evaluation Of Performance On Profile Control Agents For NB35-2Reservoirs In The Bohai Sea

There is a huge reserve of heavy oil in Bohai Sea, but the oil has high viscosity and density, theheterogeneity of the formation is severe and the interference of edge-water and bottom-water, which leadto obvious phenomenon of water-flooding breakthrough and lower than18%recovery percent. So aappropriate profile control agent is needed to restrain the breakthrough of edge-water and bottom-waterand enlarge sweeping areas. In order to improve heavy oil recovery, the viscosity, rheology, viscoelasticity,hydraulic diameter D_h, molecular configuration, flow characteristics, adsorption characteristics werestudied under the guidance of modern reservoir engineering theory, physicochemical theory, advancedinstrumental analysis, and core flooding tests, the appropriate profile control agent were screened by fuzzycomprehensive judgement, and the displacement effect of profile control and their factors were judged.The results showed that, at a lower concentration, the viscosity and thermal stability of SNF polymer ishigher than the gaofen polymer, and time stability of the gaofen polymer are better than the other twopolymers. The phenomenon of shear thinning of SNF Polymer is more obvious than gaofen polymerwhen polymers were at the same concentration, which means that the apparent viscosity of SNF Polymerbadly relied on shearing rate. The viscoelasticity of SNF polymer are higher than gaofen polymerunder the same shearing rate. When the concentration was1600mg/L, the cross-linking reaction of SNFpolymer molecular and Cr³⁺mainly occurred intermolecule cross-linking and intra-molecule cross-linkingas supplement, the reaction of SNF polymer is opposite. As the residual resistance factor was higher thandrag coefficient, the distinct porous flow character displayed by gaofen gel. And it was screened byfuzzy comprehensive judgement. The bigger the slug size and the higher the agent concentration are used,the greater recovery and the lower recovery amplification can be. The better slug size is0.050PV～0.075PV, and compose of profile control agent is gaofen polymer which concentration is1200mg/L～1600mg/L and chromium, in which the ratio of polymer to chromium is180:1～270:1.