Study On Stability And Destabilization Of The Crude Oil Emulsions

With the maturity of the polymer flooding technology,the Bohai Oilfield has expanded its application year by year and achieved good effect.After degradation,the polymer formed a low molecular weight polymer fragment,increased the stability of the crude oil emulsion,made the demulsifier ineffective and lead to the increase of the dosage of the agent and the excessive water content of the crude oil.So,it's necessary to study the stability of crude oil emulsion,design and synthesis of new demulsifier.The main work is as follows.1.We detected the demulsification process under different conditions by stability analyzer.The results showed that the stability of crude oil emulsion enhanced with increasing the concentration of colloid,asphaltene and the polymer,and decreased with increasing the water content and temperature.We also studied the change of the crude oil emulsion properties with Brookfield viscometer,K-12 surface tension meter.The colloid,asphaltene could reduce the oil-water interfacial tension,increase the oil-water interfacial film strength and improve the stability of the crude oil emulsion because of their high interfacial activity.With increase of the polymer content,the viscosity and emulsification degree of the crude oil emulsion enlarge and then lead to improving the stability of the crude oil emulsion.The increase of water content makes water droplets increase and aggregate easily.Temperatures reduce the viscosity of crude oil emulsion,sped up the thermal motion of droplets,reduce the stability of crude oil emulsion.2.The polyether demulsifier was modified with isophorone diisocyanate(IPDI)as chain extender.The structure of polyether demulsifier was characterized by 1H-NMR and IR spectra.The cloud point,water number and HLB value was determined.The aggregation behaviors at air/water interface was studied by the surface Tension.With the increase of the amount of IPDI,the critical micelle concentration(cmc)of the modified polyether demulsifier is reduced and the efficiency of reducing the surface tension is increased.The bottle test demulsification results showed that the demulsifier modified by IPDI has a better effect,and the proportion was increased from 52.3%to 84.3%.3.The polyether demulsifier was modified by polyethylene glycol or polypropylene glycol(PEG/PPG).The structure of polyether demulsifier was identified by 1H-NMR and IR spectra.The molecular weight was measured by GPC.The cloud point,water number and HLB value was determined.The aggregation behaviors at air/water or oil/water interface was studied by the surface Tension and dynamic interfacial tension.It was found that the demulsifier modified by PPG has better diffusion ability than the demulsifier modified by PEG,and reduce the interfacial tension more effectively.Through the bottle test,we found that PPG modified demulsifier is better for platform crude oil demulsification.Compared with BH123,demulsifier P400-10 has a better demulsification effect,and dehydration rate increased by 16.6%at 2 hours.