Aiming at the problems of low recovery of water flooding,high cost and high carbon emission of thermal recovery in conventional heavy oil reservoirs,anionic viscosity reducer and salt-resistant polymers were preferred based on the low-temperature and high-salt properties of reservoirs in Chunguang Oilfield.The water cut reduction and oil production increase mechanisms of hot-water flooding,single viscosity reducer flooding,and composite flooding were clarified based on indoor physical simulation experiments.The kinetic equations of the reaction of vis-cosity-reducing composite flooding were established.The numerical simulation method of viscosity-reducing com-posite flooding was developed in CMG-STARS software.Well-pattern spacing and injection-production strategy of viscosity-reducing composite flooding were optimized for conventional heavy oil reservoirs in Chun 2 unit.The re-sults show that the viscosity-reducing composite flooding could give full play to the synergistic effect of viscosity en-hancement of the displacing phase and viscosity reduction of the displaced phase,and it has the advantages of low system dosage,low carbon emission,and significant recovery enhancement;the viscosity-reducing composite flood-ing is suitable for five-spot pattern,the injector-producer distance should be less than 200 m;the optimal injection slug volume is 0.5 times of the pore volume and the injection to production ratio is 1.05 with the mass fraction of the viscosity-reducing agent at 0.25%.Practice shows that the water cut in wells was reduced by more than 30%,and the daily oil production was increased by 5 t/d after the viscosity-reducing composite flooding was implemented in extra-high water cut(water cut of 96%)reservoir at the late stage.This study confirms the feasibility of this technology applied in the field.It provides a reference to improve the effect of the development of conventional heavy oil reservoirs and realize the reduction of industrial emissions.
conventional heavy oilcomposite floodingnumerical simulationenhanced oil recoveryChunguang Oilfield
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