Synthesis and Evaluation of Copolymer Filter Loss Reducer

A quadripolymer filter loss reducer was synthesized using acrylamide (AM), 2-acrylamide-2-methyl propane sulfonic acid (AMPS), acrylic acid (AA) and dimethylaminoethyl methacrylatemethyl chloride (DMC) as raw materials through redox polymerization. The mass ratio of the four monomers is AM:AMPS:AA:DMC=55:30:10:5, the concentration of initiator 0.3% (taking the concentration of all monomers as 1), total concentration of monomers 20% (mass ratio), reaction temperature 50℃, pH of the solution 7, and reaction time 4 hours. Characterization of the molecular structure of the copolymer showed that the molecular structure was the same as design. Treatment of API standard water base mud with 0.7% copolymer reduced the API filter loss to 6.0 mL. After aging at 180℃, filter loss at 0.7 MPa was 8.2 mL, and 11.6 mL at 3.5 MPa. In hot rolling test, shale cuttings recovery of 99.4% was attained at copolymer concentration of 1.0%. These laboratory tests showed that the synthesized copolymer had good filter loss control capability, thermal stability and inhibitive capacity.