Synthesis Of Cationic Associative Polymer Acid Thickeners

The addition of the thickening agent can improve the performance of thickening acid to achieve deep acidification during the oil and gas reservoir acidification of deep well and ultra-deep well.This paper designed and synthesized three different carbon chain hydrophobic monomers firstly:DTAB,DHAB,and DOAB.Then,The PDDT-14,PDDH-16 and PDDO-18 were synthesized respectively with DMC and DMDAAC by the method of free radical polymerization.Three hydrophobic monomers of different alkyl chain were generated respectively by using dimethyl amino propyl acrylamide(DMAPAA),bromotetradecane,bromohexadecane,and bromooctadecane.The optimization conditions of monomer synthesis were determined by single factor experiment based on the reaction yield.The results are that the acetone is taken as dissolvent,the rato of solute to solvent is 1g:1.5g,the reaction temperature is 55 ?,and the reaction time is 40h.The structures of the three kinds of monomer were characterized by fourier transform IR and 1HNMR.The optimal conditions of the polymer determined by single factor experiment based on apparent viscosity are that the amount of hydrophobic monomers is 0.25%?0.3%,monomer concentration is 55%,dosage of initiator is 0.06%,PH=5,temperature of reaction is 60?,reaction time is 6h,and the dosage of chelating agent EDTA is 0.015%.The structures of the three kinds of polymers were characterized by fourier transform IR and 1HNMR.The thickeners performance was evaluated in the acid with industry standards.The results show that the PDDH-16 thickener has better acid solubility,retardation,resistance to temperature and shear resistance in the acid solution compared with PDDT-14 and PDDO-18.Based on the analysis of viscosity-concentration relationship of PDDH-16 polymer solution,fluorescence spectroscopy and scanning electron microscopy(SEM),it is proved that the cationic associative polymers synthesized in this paper can produce intermolecular association in the solution and can form a spatial network structure so as to achieve thickening effect.Thickening acid PDDH-16 has good compatibility with a variety of acid additives.The formula of thickening acid is that 20%hydrochloric acid + 0.8%PDDH-16 + 2%corrosion inhibitor WD-11+1.0%ferric ion stabilizer WD-8 + 0.5%cleanup agent WD-12A + 1.0%clay stabilizer WD-5.The thickening acid system has a good corrosion inhibition effect with corrosion rate 13.98 g/(m2·h)and corrosion rate 98.34%.And the surface tension of acid residue after acidification reached 27.60 mN/m to meet the requirements of rearrangement.Its residual acid viscosity is only 10.8 mPa·s,which is conducive to the solid suspension of the back row.