Optimization and evaluation of binary composite foam system with low interfacial tension in low permeability fractured reservoir with high salinity

The foam flooding technology can be used in low permeability fractured reservoir for tertiary oil recovery. In view of low permeability fractured reservoir with low temperature and high salinity, a binary composite low interfacial tension foam system is developed, and the composite foaming ability, interfacial tension, resistance to oil, salt and temperature of the foam system were evaluated in this paper, and then the plugging ability and oil displacement efficiency were studied. It is indicated that under the condition of 32 °C and 29 500 mg/L formation water salinity the optimized formulation of binary composite low interfacial tension foam system is selected for 0.12% W fluorocarbon foamer+0.08% QL betaine +0.1% BS betaine +1500 mg/L polymer; for the reservoir with big permeability difference existed between layers or high permeability reservoir, profile control measures are needed to be further taken before foam injection; 0.4 PV foam system and 0.1 PV profile control system were injected into the parallel core column with high permeability 1000mD and low permeability 10mD cores in the oil displacement experiment, and the recovery of low permeability core was enhanced by 18.87%. In practical application, the profile control system and its amount need to be optimized according to the actual situation.