Study On Emulsification Regularity And Demulsification-flocculation Of Produced Water In Gas Field

The addition of foaming and drainage agent can assist the drainage of natural gas production wells to achieve the function of drainage and gas recovery.However,the produced water in gas field will become O/W emulsion at the same time,which cause trouble for the subsequent reinjection of the produced water.This topic mainly studied the emulsification regularity and mechanism of produced water in gas field.First of all,on the basis of summarizing the investigation results of the emulsified background of produced water in Sulige gas field,the effects of emulsifying factors(content of foaming agent,degree of mineralization,temperature,pH,content of gas condensate,speed of agitator and emulsification time)on the emulsification degree and emulsification stability of simulated produced water were systematically studied by single factor experiments.The degree of emulsification is evaluated by turbidity and oil droplet size.The emulsification stability was evaluated with the fitting result of the established mathematical model to the turbidity kinetic curve and the decrease of the actual turbidity with the standing time.The study found that:when the foaming agent content or speed of agitator is higher,the initial emulsification degree is higher at standing still and the subsequent emulsification stability is better;When the temperature or content of gas condensate is higher,the initial emulsification degree is higher,but the emulsification stability is worse.The emulsification regularity at different temperatures or different oil contents indicate:emulsions with higher initial emulsification degree may not necessarily have better emulsification stability.As the degree of mineralization increases,the initial emulsification degree and emulsification stability all gradually decrease;In the experimental range,pH has little effect on the emulsification.The main mechanism of the effect of the foaming agent on the emulsification of produced water is that it greatly reduces the oil/water interfacial tension,changing the content of foaming agent has minor effect on the electrical effect between oil droplets.But the main mechanism of changing the mineralization degree affects the emulsification by greatly changing the electrical repulsion between the oil droplets.In the single factor experiment involved in the thesis,the initial turbidity of the simulated produced water is negatively correlated with the average particle size of the oil droplets under the premise of equal oil content;At the same temperature,the larger the average particle size of the initial oil droplets,the worse the emulsion stability.Secondly,by studying the relationship between the emulsification regularity and interfacial tension,it's found that:increasing the content of the foaming agent,degree of mineralization or the temperature will all reduce the oil/water interfacial tension,but the three factors have different effects on the emulsification regularity.Visible that interfacial tension alone can't directly judge the emulsification regularity.However,when the change rangeability of the interfacial tension is larger,the change rangeability of the initial emulsification degree is also larger under the single factor experimentFinally,the demulsification-flocculation experiment was performed with the actual produced water of gas field.Orthogonal tests were used to determine the treatment effects of different chemical agent combinations and different concentrations on the suspended solids content and oil content of the actual produced water.Screening of better dosing regimens based on range analysis.Combined with the analysis of variance to determine whether there are significant differences in the treatment effect of different agents on the degreasing and removing SS.And analyze the causes of treatment effects produced by different chemical agent.