Study On The Scale Mechanism And The Scale Inhibitor In The ASP Flooding In Daqing Oilfield

Asp flooding recovery is an important technical measure at late stage of oilfielddevelopment. Since2009, EOR blocks of Daqing oilfield have abandoned polymerflooding and adopted Asp flooding in an all-round way, with the wide use of Aspflooding, scale phenomenon exist in near bore zones and produced fluid. Theexistence of scale production not only cause hidden troubles to production, reduceproduction efficiency, increase production costs, restrict the wide application oftechnology of Asp flooding.This paper takes actual situation in4factory of Daqing oilfield as an example,studies interaction of produced fluid of Asp flooding recovery and strata rocks inoilfield exploitation process, analyzes cause of scaling of Asp flooding, and get thescaling mechanism of Asp flooding produced liquid.According to the scale forming characteristic of produced liquid in Asp flooding,a chemical scale inhibitor was established as technological core of scale preventionfrom produced liquid in Asp flooding. The reaction principle of the radicalpolymerization was determined. The synthetic tests was designed. Terpolymerpolymer scale inhibitor was self developed. Maleic anhydride （MA）, acrylic acid（AA）,2-acrylamide base-2methyl c sulfonic acid （AMPS） were adopted as thereactive monomers.（NH₄）2S₂O₈+NaHSO₃were adopted as the initiators.Deionizedwater were adopted as the solvent, this scale inhibitor was applied to the producedliquid in Asp flooding. Through investigating the influence of experimental conditionincluding the scale inhibitor main monomer molar ratio, initiating synthesistemperature, initiator partitioning exerted upon the antiscaling effect on. Hence camethe optimum synthesis conditions are n（MA:AA:AMPS:（NH₄）2S₂O₈+NaHSO₃）=0.5:1:0.019:0.0089. N2Pumped in0.5hour, invitation temperaturewas60℃, dropping time of the initiators was1.5hours; continuous reaction time was2hours. Taking simulated field injection water and produced liquid for research object,evaluation method of scale inhibitor of synthesis of Asp flooding was established. Atthe same time, according to present experimental condition of3-Dimension complexdrive, effect of scale inhibitor of synthesis was evaluated on different study system.Experiment showed that comprehensive inhibiting rate of scale inhibitor of synthesisreached over85%at the amount of20mg/L.For validating scaling mechanism and synthesis of scale inhibitor, this paperadopted scanning electron microscope, energy-dispersive x-ray analysis, Fourierinfrared spectra analysis and other analytical method. Test date consistence toresearch results above.