Study On Produced Fluid Treatment And Antiscaling Technologies In Weak Based ASP Flooding Producing System

Recently,in order to lessen adverse effect of alkali on viscosity,emulsification of production fluid and scaling,alkalescent alkaline surfactant polymer?ASP?is adopted to replace alkali ASP flooding in oilfields.According to the characteristics of the second type oil layers reservoirs of Lamadian oilfield,the laboratory experiments and field tests of weak base ASP flooding were carried out.The stability mechanism of weak base ASP flooding system was determined,and the scale prediction model and equation were established.In order to effectively solve the problem of scaling and scale removal of weak base ASP flooding system,the technology of crude oil,sewage,filtration and deep sewage treatment was carried out.The main contents of this paper are as follows.The viscosity and produced liquid water phase viscosity of ASP flooding mainly depended on the content of polymer.With the increase of polymer concentration,the viscosity of the ASP system was increased,and the viscosity of the polymer was decreased.The surfactant had little effect on the viscosity of the system.The coexistence of ASP systems,the influence of surfactant and alkali phase viscosity on water has been offset.After the injection of ASP system into the stratyn,the formation of a large number of aluminosilicate,alkali erosion of the stratyn can result in a larger concentration of silicate ions,which showed a balance state with the Ca²⁺and Mg²⁺.Once the oil well temperature,pressure and kinetic conditions changed,the ion balance was broken,which resulted in chemical precipitation and deposition of scale.The scale of the ASP flooding mainly existed in the form of calcium carbonate,magnesium carbonate and silicate.According to the prediction equation of carbonate and silicate scale,the stability index of the produced fluid is about 4.0⁵.0,which is in the stage of carbonate serious scaling and silicate slight scaling.The content of water stabilizer dosage and produced water ions can be directly related to the formation of carbonate.When the calcium concentration was larger than 30mg/l and carbonate content was greater than or equal to 100mg/l,the water stabilizer should be added in.Fluorocarbon coatings exhibited excellented corrosion resistance and corrosion rate was lower than 0.025mm/a,which can be used in ASP flooding system for pipeline corrosion and scale prevention.The scale of ASP produced liquid was affected by the concentration of acid solution,temperature and reaction time.The most suitable scale was HCl7%+HF5%,and the best scale and time was 40?and 6h.Cavitation scale prevention technology can be used to ASP flooding system,the liquid temperature of 42?,cavitation scale prevention technology showed obvious inhibitory effects on the calcium and magnesium ions deposition,especially as the concentration of Ca²⁺and Mg²⁺ions was 1200 mg/L.The cavitation scale prevention technology can prevent the scaling of calcium,magnesium and silicon for the ASP flooding system,and can be applied in the collection and transportation system of ASP flooding.pH,HCO₃^-,OH^-,viscosity and surface active agent were the main factors affecting the ASP sewage treatment.Demulsification and viscosity reduction was the key technology.The dehydration rate was highest when the frequency of the pulse electric dehydration of ASP is close to that of the natural frequency of droplet oscillation in emulsion.The chlorine dioxide can be used to handle the ASP produced liquid,and the optimum concentration was about40mg/L.Suspended sludge filter can effectively remove small suspended solids in ASP produced sewage.After the depth of the water treatment for 48 h filtration cycle,the suspended solids removal rate was 75.7%,and the content was less than 5mg/L,which can meet the water quality index.