Preparation And Performance Evaluation Of Copolymer Scale Inhibitor Based On β-cyclodextrin

The most oilfield has been suffering serious scaling problems in China,due to the security and economic issues become increasing serious,calcium carbonate scale is the most common inorganic scale in oilfield.Especially,the phosphate salt sacle inhibitor is widely used in oilfield.However,it tend to be secondary scaling,which cause serious pollution to the environment.Therefore,it,s very important to develop an easily biodegradable,"green",efficient and environmental friendly scale inhibitors.In this article,the beta-cyclodextrin(p-CD),maleic anhydride(MA)and 2-acrylamide-2-methyl propane sulfonic acid(AMPS)were used as monomer to synthesis scale inhibitor CM-AMPS.Single factor experiment method was used to optimize synthesis conditions.The best synthesi’s condition was as follows:p-CD:AMPS:MA monomer mole ratio=1:8:2.5,the reaction temperature was 80℃,reaction time was 12 hours,and amount of initiator accounted for the total monomer mass was 10%.When the dosage of scale inhibitor was 12 mg/L,the calcium carbonate scale inhibition rate was 91.5%.The CM-AA scale inhibitors was syntheised by beta-cyclodextrin,maleic anhydride and acrylic acid(AA).The best synthesis condition was as follows:beta CD:AA:MA monomer mole ratio=1:8:2,reaction temperature was 80℃,the reaction time was 8 hours,and amount of initiator accounted for total monomer mass was 12%.When the dosage of scale inhibitor was 8 mg/L,the behaviors of the calcium carbonate scale inhibition rate was 93.3%,which was better than the commercially available drugs.At the same concentration of calcium ion,the scale inhibiton rate of CM-AA scale inhibitor was 35%higher than that of MA-AA scale inhibitor.Three methods were used to get the competitive rate of the monomer of CM and AMPS,and the results showed it was the nonideal copolymerization.By measuring the conductivity of supersaturated solution,the calcium carbonate with scale inhibitor crystallization kinetics curve was got.The X-ray diffraction analysis and scanning electronmicroscopy(SEM)method were used to analyze the scale inhibition mechanism.The carboxylic acid ions of the copolymer combined with calcium ion,which adsorpted on the surface of calcium carbonate embryos,preventing the normal growth of the crystal.Cyclodextrin cavity structure had a space steric effect on the scale inhibtion,which disturbed the normal order of crystal growth,dislocating the crystal growth,cutting the effective collision between particles.The experimental results showed that adding copolymer seale inhibitors suppressed the crystal growth and ehanged the morphology of crystal,and the copolymer scale inhibitor had a good scale inhibition effect on calcium carbonate.The scale inhibitors(CM-AA-PA)containing fluorescent monomer was measured by infared spectroscopy,nuclear magnetic resonance hydrogen spectrum method and thermogravimetric analysis method.By measuring the relationship between the scale inhibitor concentration and fluorescence intensity,the detection limit of scale inhibitor was 1.37 mg/L.