Preparation And Experimental Study On The Compound Scale Inhibitor Of Barium, Calcium And Strontium Ions

In the oilfield development, due to the change of underground temperature,pressure, the thermodynamics instability of water and chemical incompatibility,which make the oil casing in the bottom, equipments on the ground and down holeand pipeline occurre scaling phenomenon. Among them, sulfate scaling was themost harmful.This paper studied the scale inhibition performance of coal-based scaleinhibition (SHA)which was obtained by humic acid in coal after sulfonatedtreatment and three polymer scale inhibitor composite stabilizer which werecompound by several monomers maleic anhydride (MAn),acrylic acid (AA),methacrylate (MAc),NaH2PO2(P),and etc.Discussed the effect of the dosage ofinitiator, reaction temperature, reaction time in the synthesis process on the scaleinhibition performance of copolymer scale inhibitor to barium ion, obtained thebest synthesis condition of copolymer scale inhibitor, then verified the scaleinhibition of copolymer scale inhibitor to calcium, barium, strontium ions. Staticscale inhibition method was taken to evaluate the scale inhibitionperformance.Results showed that, the scale inhibition rate could reach95.68%under the condition of sulfonated humic acid dosage20mg, the concentration ofcalcium647.545ppm, the scale inhibition rate could reach83.39%under thecondition of sulfonated humic acid dosage60mg, the concentration of barium954.446ppm, the scale inhibition rate could reach80.92%under the condition ofsulfonated humic acid dosage850mg, the concentration of barium529.891ppm.The scale inhibition rate of the polymer scale inhibitorMAn-AA-MAc to calcium, barium and strontium ions could reach maximum90.34%,74.31%,84.26%, when the dosage was75mg,125mg and80mg,respectively. MAn-AA-MAc was synthesized under the condition of reaction time6hours,85℃, the dosage of initiator1.2%.The scale inhibition rate of the polymerscale inhibitor MAn-P-AA to calcium, barium, strontium ions could reachmaximum91.71%、76.03%,and85.04%, when the dosage was50mg,80mg and 80mg, respectively. MAn-P-AA was synthesized under the condition of reactiontime6hours,75℃, the dosage of initiator2.4%.The scale inhibition rate of thepolymer scale inhibitor MAn-P-AA-MAc to calcium, barium and strontium ionscould reach maximum92.76%,78.26%, and85.35%, when the dosage was60mg,90mg and70mg, respectively. MAn-P-AA-MAc was synthesized under thecondition of reaction time4.5hours,85℃, the dosage of initiator2.4%.The scaleinhibition rate for barium could reach84.33%, when the volume ratio of SHA toMAn-AA-Mac3:1, the dosage60mg, the concentration of barium954.446ppm.The scale inhibition rate for barium could reach85.68%, when the volume ratio ofSHA to MAn-P-AA1:1, the dosage60mg, the concentration of barium954.446ppm.The scale inhibition rate for barium could reach88.59%, when thevolume ratio of SHA to MAn-AA-Mac2:1, the dosage60mg, the concentration ofbarium954.446ppm.Testing the performance of the three composite stabilizer scale inhibitorunder the different concentration of calcium, barium and strontium, the compoundscale inhibitor had the characteristics of small dose and high scale inhibition ratecompared with single scale inhibitors effect. And scanning electron microscope(SCE) and XRD patterns were employed to study the characterization, the resultsindicated that composite stabilizer scale inhibitor had good scale inhibitioneffect.Preliminary study on the mechanism of composite stabilizer scale inhibitor,compared with single scale inhibitor, multifunction group of composite stabilizerscale inhibitor had significant compatibility, and the small dose effect, chelationeffect and charge dispersion to barium and strontium were obvious.