Investigations Into The Development Of Polymer/Surfactant Binary System And Its Displacement Efficiency Under Conglomerate Reservoir

The conglomerate reservoir is an important part of oil and gas resources in our country.Under the situation of increasing crude oil demand in our country,it is necessary to research how to increasing oil recovery of conglomerate reservoir.Most of the reservoirs in Xinjiang Oilfield is conglomerate reservoirs.With long-term and continuous development of reservoirs,the previous water-flooding method can no longer meet the production demand,so it is necessary to carry out the related work of chemical flooding.Because the Xinjiang Oilfield is located in Karamay City and lack of freshwater resources.This research focus on hyperbranched polymer solution with produced water.According to the structure characteristics of hyperbranched polymers,the geologic features of the conglomerate reservoir and crude oil properties in Xinjiang Oilfield,the prepared hyperbranched polymer binary system made up with produced water was studied for the adaptability of the reservoir and the efficiency of oil displacement.Based on the experimental research,this research screened out the KPS-1+L5 surfactant system and mixed with hyperbranched polymer or KYPAM to form a polymer/surface-binary system.Through Lab experiment to study the displacement efficiency on the target conglomerate reservoir.The interfacial tension between the surfactant system KPS-1+L5 and crude oil is on the order of 10-3mN/m.Through the experiment,it was found that surfactant system KPS-1+L5 could change rock wettability from oil-wetting to water-wetting.Under the reservoir conditions,the surfactant system and crude oil had good emulsifying performance.The adsorption capacity of the surfactant system on the conglomerate cuttings was about 1.57mg/g.Furthermore,the performance of the binary system of surfactant system and hyperbranched polymer or KYPAM was evaluated.The surfactant system was reduced the viscosity of the hyperbranched polymer and KYPAM solution,but the retention viscosity of hyperbranched polymer binary system above the KYPAM binary system.The interfacial tension between the binary system and the crude oil was between the order of 10-3mN/m and 10'2mN/m.After 90 days aging,the interfacial tension stabilized at about 10-1mN/m.The wettability and emulsifying experimental results showed that the hyperbranched polymer binary system was better than the KYPAM binary system in the wettability improvement of the oleophilic conglomerate sheet.After conglomerate sheet immersing for 48 hours in the solution,the contact angle changed from 1550 to 42.1°.When the water-oil ratio was 5:5,the binary systems of HBPAM and KYPAM polymers can be emulsified with dehydrated crude oil.The polymers and surfactants can solubilize in the crude oil to form W/O or[O(W/O)/W]emulsion,and the viscosity of the emulsion was higher than the crude oil.The flooding efficiency of polymer and binary system was studied by physical simulation in laboratory.The displacement effect of single hyperbranched polymer was better than that of KYPAM,and the recovery of conglomerate core was increased by about 20%.The oil displacement results of the binary system showed that the binary system used in the experiment had a good EOR effect in the conglomerate core,and the oil displacement effect of the hyperbranched polymer binary system was better than that of the KYPAM binary system.The recovery was increased by 26.7%?30.9%in the small core.When the core parameters are similar,as the viscosity of the hyperbranched polymer binary system increaseed,the oil displacement efficiency increaseed.Therefore,it is suggested to select hyperbranched binary system with high viscosity for oil displacement under the condition of satisfying the injectivity.The mechanism of oil displacement of hyperbranched polymer binary system was studied by microscopic experiment.The hyperbranched polymer binary system played a synergistic role between polymer and surfactant flooding in the process of oil displacement.Through the viscoelastic effect of polymer,interfacial tension reduction and surfactant emulsification,the oil displacement efficiency in the conglomerate cores was improved.