Effects of Polymer Sidechains on Performance of Oil Well Cement Filter Loss Reducers and Studies on Mechanisms of the Effects

To understand the relationship between the molecular structure and the performance of copolymers used as oil well cement filter loss reducers, as well as to guide the molecular structure design of new ultra-high temperature and salt resistant filter loss reducers, the effects of polymer sidechains on the filtration control performance of the copolymer filter loss reducer were studied through molecular kinetics simulation and laboratory experiment. The mechanisms of the copolymer’s ability to resist high temperature and salt contamination were also investigated. Laboratory experimental results show that the introduction of rigid benzene side groups into the final copolymer reduces the API filtration rate of a fresh water and a saturated saltwater cement slurry after being aged at 240 ℃, meaning that the copolymer has excellent ultra-high temperature and salt-resistant performance. Molecular kinetics simulation results show that the introduction of the rigid benzene side groups increases the gyration radius of the copolymer segments, weakens the dehydration effect of the large amount of counterions (Na⁺ and Ca²⁺) on the functional groups of the copolymer. This is beneficial to the adsorption and hydration of the filter loss reducer molecules on the surfaces of the cement particles, and gives full play to its original use efficiency.