Study On The Percolation Property And Flooding Effect Of Polymer Gel In Bohai Oilfield

Bohai oilfield is characterized by large reservoir thickness, high average permeability, serious heterogeneity, high viscosity of crude oil and high water salinity, which influenced greatly the oilfield water flooding development results. Therefore, it is urgent to take technical measures for profile controlling in order to expand swept volume. In recent years, polymer flooding and polymer gel flooding field test have been carried out in SZ36-1 and LD10-1 oil field,with an obvious effect in increasing oil production and decreasing water production, but the existing polymer powder curing technology can not fully meet the needs of Bohai oilfield flooding technology, and how to shorten the polymer powder curing time is problem which technical personnel concerned. According to the Bohai oilfield development technology requirements, optimization for soluble polymer and its polymer gel composition and performance evaluation has been conducted and study on polymer gel reservoir adaptability for profile controlling has been carried out through reservoir engineering, physical chemistry and polymer chemistry as theoretical guidance, instrumental analysis, chemical analysis and physical simulation as technology, the viscosity properties, rheological properties, seepage characteristics and oil displacement efficiency as the evaluation index and the geological characteristics and fluid properties in Bohai main oilfield as engineering basis. The results show that using the orthogonal test method and the viscosity as the evaluation index,optimization of polymer gel combination is the production of instant polymer Shengli oil field(CP=3000mg/L), organic chrome crosslinking agent(poly Cr3+=270:1). The level of each factor of properties of polymer gel changes impact on the comprehensive index important degree sequence is polymer concentration > polymertype > cross-linking agent type > poly: Cr3+. Compared with the same concentration of polymer solution, Cr3+ polymer gelresistance coefficient and residual resistance coefficient is larger, and the injection pressure during the subsequent water flooding stage did not fall but rise, showing the unique seepage characteristics. Cross linking agent Cr3+ and polymer can occur crosslinking reaction in porous media,and the higher permeability and the bigger pore space size, the better gelling effect,and the gelling effect in static conditions is better than the one in dynamic conditions. With the average core permeability and the permeability variation coefficient increaseing and flooding time advanced, polymer gel flooding oil increasing effect is better. Based on physical simulation method and recovery index, optimization of Cr3+ polymer gel composition should be as follow: Shengli oilfield production of instant polymers,Cp=1000mg/L ~ 2500mg/L. The crosslinking agent is the organic chromium “crosslinking agent 3”, "poly:Cr3+" =120:1 ~ 270:1. Slug size ranges from 0.05 PV to 0.15 PV.