Swelling kinetics of PPGs based on collective diffusion model
Preformed particle gels(PPGs)are polymer gel materials with high water absorption characteristics,which have been widely applied in water shutoff in oilfields.The water swelling property of PPGs is closely related to the nature of the gel network structure,and the swelling kinetics method is a simple way to evaluate the gel network structure characteristics of PPGs.The characteristics of the Voigt model and the THB co-diffusion,were compared and analyzed.The swelling kinetic formula of r-THB model was obtained by reasonable equivalent spherical hypothesis and formula simplification.The collective diffusion coefficient(Dc)was used as a characteristic parameter to characterize the gel network structure,which was com-posed of three components:the mixed term(Dmix),the elastic term(Del),and the ionic term(Dion).And he influencing factors and variation rules of Dc were analyzed.The results show that Dc increases with the increase of the crosslinker con-tent,which is due to the increase of Del caused by the increase of crosslinker concentration.Dc decreases with the increase of salt concentration,which is mainly due to the decrease of Donnan equilibrium osmotic pressure,thus reducing the Dion.The research method of gel swelling kinetics based on the r-THB model provides a simple and effective way to characterize the gel network structure properties.
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