Study On Mechanism And Domain Factors Of Scale Formation In Alkaline-surfactant-polymer Flooding

The alkaline-surfactant-polymer (ASP) flooding is newly developed to enhance oil recovery.The field tests found that scale in the ASP process was deposited on the produced systems, whichis a great trouble in the oil production. It is necessary to study mechanism of the scale formationfor support of theory on avoiding the scaling.Based on the oil production of Daqing oilfield, physical and chemical processes of scaleformation were analyzed. The mechanism of scale formation was proposed.Focusing on the silicate systems in artificial mineralized water, the micro-structure picturesof the silica scales were observed in different solutions (high Si4+ solution, middle Si4+ solution,low Si4+solution with/without Ca2+, Mg2+, PAM and surfactant) by the microscope and SEM atroom temperature. The micro-structure was varied in different systems.By spectrophotometer, the simulation tests tracked and monitored forming of the silicascale in aqueous solution with/without Ca2+, Mg2+, Al3+, PAM and surfactant on the differentfactors, that is, temperature, pH value, PAM, surfactant and friction. The experimental resultsshow that the coexistence of Ca2+, Mg2+ and Al3+ was found a domain factor affecting the scaleforming. The scale forming depends on temperature, pH value and co-ions of Ca2+, Mg2+ andAl3+.By virtue of chemical and instrumental analysis (FTIR, XRD, TG/DTA and AAS), thecharacter of scales obtained in the above experiments was performed. The results displayed thatthe composition and structure of the scales are consistent with the theoretical analysis.