Study On The Properties Of Demulsification Of Polymer-containing Produced Fluid And Retention Of Polymer In Sewage

In recent years,the water content of China's petroleum produced fluids has become higher and higher,and even some of them have reached 95%.Due to the extensive use of polymers and the increase of resins and asphaltenes in crude oil,the crude oil emulsions have become more complex.It is difficult to achieve high-efficiency demulsification for this kind of crude oil produced fluid by the conventional demulsifiers and demulsification technologies.The main problem is the increase in the amount of aging oil and polymer-containing sludge after treatment with conventional methods.The existence of aging oil seriously affects the dehydration of crude oil,and the production of polymer-containing sludge not only causes a large amount of crude oil loss,but also causes serious environmental pollution problems.In response to the above problems,this paper develops a new comprehensive treatment demulsification agent for demulsification based on the theory of colloidal interface chemistry.The principle of"source treatment"was studied in order to achieve the comprehensive treatment of"crude oil dehydration"and"sewage purification"simultaneously.Control the generation of oily sludge to reduce the amount of pollutants;at the same time retain the polymer in the sewage,dispense and increase the viscosity,and then reuse the polymer in the sewage.Demulsifiers with linear,branched,and hyperbranched structural model was synthesized in the paper.The demulsification effect of the model demulsifier on polymer-containing emulsions was studied.The branched chain demulsifier has better demulsification effect than the straight chain demulsifier,and the hyperbranched demulsifier has better demulsification effect than the branched chain demulsifier.The polyether nonionic demulsifier alone has a poor demulsification effect on the polymer flooding emulsion,but the demulsification performance is significantly improved after being compounded with the reverse phase demulsifier.Under the best conditions,the rate of water and of oil can reach 100%.The microscopic properties of the oil-water interface show that the polyamide-amine hyperbranched polyether demulsifier with high degree of branching and high molecular weight has a high interface activity and can significantly reduce the interfacial tension of the simulated emulsion;at the same time,the polyamide-amine hyperbranched polyether demulsifiers are easy to be adsorbed at the oil-water interface,changing the structure of the interfacial membrane of the simulated polymer flooding emulsion and weakening the interfacial membrane strength.On the basis of the structure-effect relationship of the above model demulsifier,a comprehensive treatment agent for the produced fluids was developed,and field experiments were conducted on the polymerized produced fluids in Dagang Oilfield and Shengli Oilfield.After treatment,the water content of crude oil is less than 1%,and the oil content of sewage is less than 50 mg/L.At the same time,the polymer in the oil production sewage was retained,and the polymer retention rate was higher than 90%.The polymer retained in the sewage is low molecular weight,high degree of hydrolysis HPAM,with a certain viscosity.When fresh high molecular weight polymer is prepared by using sewage containing retained polymer,the viscosity loss of fresh high molecular weight polymer prepared by sewage can be reduced.This is because Ca²⁺,Mg²⁺,Fe²⁺,and S^2-in the sewage all affect the viscosity of the prepared high molecular weight polymer solution,which reduces the viscosity.the high molecular weight is prepared by polymerizing?low molecular weight,high hydrolysis degree polymer?sewage After the polymer solution,the remaining low molecular weight,high hydrolysis degree polymer can act as a sacrificial agent to interact with Ca²⁺,Mg²⁺,Fe²⁺,and S^2-,etc.,to offset the loss of viscosity of these ions to the high molecular weight polymer solution,thereby increasing the viscosity effect.That is to say,the use of polycondensation wastewater to prepare fresh polymer polymers can reduce the amount of high molecular weight polymers,save the cost of oil displacing agents,and reduce the discharge of polymerized sludge.