Synthesis and application of 2‐acrylamido‐2‐methyl propane sulfonic acid/acrylamide/N,N‐dimethyl acrylamide/maleic anhydride as a fluid loss control additive in oil well cementing

Using 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS), acrylamide (AM), N,N‐dimethyl acrylamide (NNDMA), and maleic anhydride (MA), a new dispersive type fluid loss control additive (FLCA) AMPS/AM/NNDMA/MA (PANM) was synthesized by free radical aqueous solution copolymerization, and the new FLCA could be used without dispersant existing in the cement. The optimal PANM (OPANM) was obtained under the optimum reaction conditions: mole ratio of AMPS/AM/NNDMA/MA = 4/2.5/2.5/1, monomer concentration = 32.5%, amount of (by weight of monomer) ammonium persulfate/sodium bisulfate = 1.0%, pH value = 4, and temperature = 40°C. The synthesized copolymer OPANM was identified by FTIR analysis. The evaluation results show the OPANM has excellent dispersing power, fluid loss control ability, thermal resistant, and salt tolerant ability. The OPANM was even stable when the temperature was below 300°C proved by TG analysis. The thickening time of the slurry containing the synthesized additive reduces as the temperature increases. The copolymer OPANM is expected to be an excellent FLCA.