| Due to the introduction of the alkali in ASP flooding, leading to the formation of a large number of produced liquid silicon scale in production system. Silicon scale is difficult to remove when it is once formed, bringing security risks and economic losses to the normal production and operation of the oilfield. Currently, oilfield antiscale technology is mainly divided into chemical method and physical method. In order to avoid the corrosion of chemical scale inhibitor, it can be used in combination with corrosion inhibitor. Meanwhile,ultrasonic antiscale is a physical anti-scaling technology with high efficiency and environmental protection.By aconitic acid as the main body in the copolymer, ammonium persulfate as initiator,two kinds of new silicon copolymer scale inhibitor were synthesized. By single factor and orthogonal experiment, the optimum synthesis conditions were determined. The system temperature, pH value and dosage to impact anti-scaling rate were discussed. Combined with the comparison of XRD, FT-IR and SEM analysis, the antiscaling agent mechanism was studied. The following conclusions were obtained:(1) By aconitic acid(AA), diethanolamine(DEA), citric acid(CA), acrylamide(AM) as monomers, the scale inhibitor ADCA was synthesized. The optimum conditions: the polymerization temperature was 75 ℃, the polymerization time was 2h, the mass ratio of per sulfate ammonium to total monomer was5%, n(AA):n(DEA):n(CA):n(AM) = 2.0:1.0:1.0:1.2. When adding amount of 70mg/L, silica scaling scaling rate was measured 77.84%.(2) By aconitic acid(AA) and citric acid(CA),acrylic acid(AA), AMPS as monomers, the scale inhibitor ACAA was synthesized. The optimum conditions: the polymerization temperature was 70℃, the polymerization time was3 h, the mass ratio of per sulfate ammonium to total monomer was 15%,n(AA):n(CA):n(AA):n(AMPS)= 2.0:1.5:1.0:0.8, When adding amount of 80mg/L, silica scaling scaling rate was measured 76.23%. The two kinds of anti fouling agent were suitable for low temperature and weak alkali environment, and the mechanism of them were mainly adsorption and dispersion.A new type of corrosion inhibitor was synthesized, By single factor and orthogonal experiment, the optimum synthesis conditions were determined. The dosage to impact corrosion inhibition rate was discussed. At the same time, two kinds of anti fouling agents were complex respectively. Their complex effects were investigated. The following conclusions were obtained: By acrylic acid(AA), triethanolamine(TEA) as monomer,ammonium persulfate as the initiator, the copolymer corrosion inhibitor A-T was synthesized.The optimum conditions: the polymerization temperature was 60℃, the polymerization time was 4h, n(AA):n(TEA)=1:1, the mass ratio of per sulfate ammonium to total monomer was3%. Under simulated conditions, adding amount of 80mg/L, carbon steel corrosion rate was92.06%. Corrosion inhibitor A-T product with ADCA antiscale rate was 77.91%, the corrosion rate was 94.81%, and product with ACAA the antiscale rate was 76.19%, the corrosion rate was 95.44%.High or low frequency of single and double ultrasonic effect on silicon ions were investigated, and the effects of its scale were evaluated. Combined with XRD, SEM comparative analysis, the antifouling mechanism of ultrasonic wave was discussed. Adding the anti-scaling agent method and ultrasonic method were briefly reviewed. The following conclusions were obtained: Under the same conditions, the antiscale effect of the low-frequency double ultrasonic was better than others. Ultrasonic antiscale mechanism was mainly cavitation and shearing action. Two kinds of anti fouling methods had their advantages and disadvantages, the operation should be combined with oilfield actual need to choose suitable and effective antiscale method. |
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