The Synthesis Of A Macromolecular Surfactant And The Application Of Its Compound System In Low-Permeability Reservoir

The oil recovery of low-permeability reservoir is low.The application of normal surfactant flooding always has poor effect with weak emulsification.However,macromolecular surfactant,as a kind of novel surfactant,is cheap and has stronger ability to disperse oil droplets.Therefore,macromolecular surfactant has a broad application prospect.In this paper,a macromolecular surfactant was synthesized,and a compound system was made by compounding with CTAB.Compound system was selected from three aspects: interfacial activity,spontaneous emulsification and emulsion stability.Multiple light scattering theory was used to assess the emulsification ability of compound system.Then,the mechanism of spontaneous emulsification and emulsion stability was explored.Finally,the mechanism of enhanced oil recovery was revealed by doing displacement experiments.The results show that the system shows best spontaneous emulsification when the concentration is 3000 mg/L and mass ratio is 7:3(PVA-1570:CTAB).Under this condition,the compounding system causes the oil to enter the water quickly,and spontaneous emulsification occurs instantaneously.Moreover,the strength of the oilwater interface film of the compound system is large,and the stability of the final spontaneous emulsification system can be enhanced.In addition,the displacement results show that the compounding system can increase the recovery rate of low permeability reservoirs by 7.4%-12.4%.The injection of the compound system reduces the injection pressure.Therefore,the water phase easily enters the formation.The number of capillary tubes is enlarged.Finally oil starts moving effectively.And the spontaneous emulsification,which occurs during the injection process,improves the oil washing efficiency,and finally improves the oil recovery of the low permeability reservoir significantly.