Research Of Scaling Behaviour In Strong Base ASP Flooding Injection System

The alkaline-surfactant-polymer(ASP) flooding is an effective way to enhance oilrecovery(EOR) during the production of tertiary recovery in Daqing Oilfield. However, theadd of the strong base caused serious scaling problem, which restricts application of ASPflooding. Consideraing this situation, this thesis conducted intensive research on scaling lawsand influencing factors during ASP injection system, then built a predictive method ofinjective system scaling.Based on the injection system process,6iconic positions’ scale samples were chosen todo composition and structure analyzed by many ways, for instance, TEM/IR/XRD andchemical analysis, the result shows that: the key components of injection system scales wascarbnate and magnesium base scale，these accounts for more than80%of the amount of scale.There are differences among scale samples, the sample from caustic soda tank contain moreMg scale than others, which could as high as10%, the scale from Static Mixers and injectionpump have more than one-tenth PAM. The structures are diverse too. Because of Mg, theCrystallization of calcium carbonate is effected, the scale is in a loose form; the sample fromeStatic Mixer gets better crystallized, the whiskers can be seen, the Injection pipeline scalinghas Lamination in a obvious way, the structure of the bottom one is honeycomb-likearrangement, while the surface got big Calcite forms.In order to figure out the effective of chemical agent bring into Ca\Mg scaling, theexperimental group designed five set inhouse laboratory investigation, including alkali system,Alkali-PAM system, Alkali-surfacant system, Ba system and ASP system, the concentrationof Ca/Mg were monitored in a following way. when the alkali mass fraction of solute ishigher than0.6%, the initial velocity of Ca2+scaling would be lower if the alkali constrationget higher, the equilibrium concentration of Ca2+would not change; PAM can retardation thescaling, surfacant can restrain from scaling to a certain degree, Ba2+and Ca2+has scalingcompetition, they affected the scaling velocity of each other; Mg scaling is a transientresponse as well as the OH-was sufficient, and the scale amount was manipulated by thecontent of Mg2+, while the content of ASP below20%, the mount of scaling will rise as wellas ASP content, when its more than20%, the change is negligible.On the basis of above，this paper does a series of researching and developing work aboutpredicting the scale formation in ASP Injection system, including caustic soda tank, injectionpipeline and shaft. Ca ion distribution, fluid viscosity at different positions and otherinfluence factors were considerded; the prediction of injected system was founded.