Feasible Experimental Study On EOR In UDM Oilfield

After water flooding development, UDM oilfield has already entered the high water cut period with the water cut reaching 92%. In order to achieve the effect of stabilizing oil production and controlling water cut during the high water cut period, enhanced oil recovery technology after water flooding development was studied in this paper, and the best project of the block can be optimized.By evaluating the viscosifying ability, temperature tolerance, thermal stability, adsorbability, injectability and displacement characteristics of several common salt resisting polymers, the feasibility of polymer flooding in this block can be studied in this paper. The results indicate that, the performance of polymer of Beijing HuaDing which has good compatibility with the formation are superior to these of other common salt resisting polymers under practical reservoir condition. On the basis of water flooding, the recovery after polymer flooding can be increased by 5.1%-12.8%. Laboratory displacement experiment has a good effect. Considering polymer dosage and the improvement of recovery, the project of concentration 2000mg/L and slug 0.6PV can be optimized.By evaluating the ability of improve oil/water interfacial tension, adsorbability and displacement characteristics of several common surfactants, the feasibility of surfactant flooding in this block can be studied in this paper. The results indicate that, surfactant HDS can effectively improve oil/water interfacial tension, but shows higher adsorption capacity in the reservoir. On the basis of water flooding, the recovery after surfactant flooding can be increased by 1.6%-6.6%. Considering the improvement of recovery, the project of surfactant mass fraction 0.2% and slug 0.6PV can be optimized.By evaluating viscosifying ability, the ability of improve oil/water interfacial tension and displacement characteristics of binary system admixed polymer of Beijing HuaDing with surfactant HDS, the feasibility of P/S binary system flooding in this block can be studied in this paper. The results indicate that, the performance of P/S binary system can meet the requirement and laboratory displacement experiment has a good effect. On the basis of water flooding, the recovery after P/S binary system flooding can be increased by 10%-15%. The project of slug 0.4PV and polymer concentration 2500mg/L+ surfactant mass fraction 0.2% can be optimized.By measuring carbonate content of natural core in this block, analyzing exothermic effect of sulphuric acid and water and measuring the improving effect of core permeability by sulphuric acid, the feasibility of sulphuric acid flooding in this block can be studied in this paper. Finally, the displacement characteristics of sulphuric acid can be evaluated and the injection rate can be optimized through laboratory displacement experiment. The results indicate that, carbonate content of carbonated natural sand is between 83.08% and 90.49%, with an average of 86.96%. It can be seen that carbonate content of practical reservoir is higher than 85%. When increasing the injection rate of sulphuric acid from 0.1PV to 0.2PV, displacement characteristics of sulphuric acid is obvious, with the recovery increasing from 8.95% to 10.73%. While the injection rate reaches 0.3PV, a large number of gypsum can be produced by the reaction of excess sulfuric acid and carbonate, which will cause serious injure on cores and bring in rapidly rising injection pressure, with no liquid producing from the exit end. Sulphuric acid flooding makes good influence on displacement characteristics, on the basis of water flooding, the recovery after sulphuric acid flooding can be increased by 7-10%. The optimal injection rate of sulphuric acid is 0.2PV.