Preparation and Performance Study of Zwitterionic Polymer Suspending Agent

With the gradual development of exploration and production towards deep and ultra-deep wells, the high temperature at the bottom of the well puts forward higher requirements for the settlement stability of oil well cement slurry. Traditional suspension agents often adversely affect the rheology of cement slurry on the basis of improving the settlement stability of cement slurry, which is not conducive to cementing construction under complex well conditions. In response to the problem of “low temperature thickening and difficulty in ashing” of liquid organic suspension, a series of zwitterionic polymer liquid suspension agents BCJ-L1 ~ BCJ-L5 were prepared by using sodium allyl sulfonate (SAS), hydrophobic monomer methacrylamide and cationic monomer A as materials through free radical water-soluble polymerization method. The infrared spectroscopy results showed that all monomers participated in the polymerization reaction. In order to explore the influence of molecular structure on the rheological properties and suspension properties of amphoteric polymers, the apparent viscosity change of the suspending agents BCJ-L1 ~ BCJ-L5 solutions were evaluated by rotational rheometer. And the effects on the sedimentation stability of cement slurry at 150 ℃ were tested. The results showed that the cationic monomer feeding amount was negatively correlated with the apparent viscosity of BCJ-L solutions. Moreover, the cationic monomer feeding amount was negatively correlated with the settlement stability of the cement slurry with BCJ-L at 150 ℃. When the feeding ratio of cation and anionic monomer was 1:2, the suspension agent BCJ-L5 could control the density difference of cement slurry at 150 ℃ within 0.01 g/cm3 and has good application prospects as it has no negative impact on ashing, fluidity, water loss and thickening properties of cement slurry.