A Novel Profile Control Agent in High-Temperature and High-Salinity Reservoirs: Dispersed Particle Gel Prepared from Modified Nanographite-Strengthened Bulk Gel

A high-temperature- and high-salinity-resistant dispersed particle gel (DPG) was successfully prepared by shearing a modified nanographite-strengthened bulk gel. Through the preparation requirements, a modified nanographite-strengthened bulk gel was prepared using a modified nanographite hybrid polymer and monomer cross-linkers. The effect of the nanographite hybrid polymer, cross-linkers, temperature, and salinity on the gel performance of the strengthened bulk gel was systematically studied. The higher proportion of bound water and the dense three-dimensional network structure of the strengthened bulk gel are the keys to temperature and salinity resistance. Rheological test results show that the bulk gel had excellent viscoelasticity. The effects of temperature, salinity, and aging time on DPG coalescence were studied from the perspective of micromorphology and particle size. The accelerated thermal motion at a high temperature increases the probability of collision and coalescence between particles. The high-salinity compression diffusion double layer reduces the electrostatic repulsion between particles. Finally, the strengthening mechanism of DPG by the modified nanographite was discussed. The high-temperature- and high-salinity-resistant DPG may be an alternative for profile control and water plugging in deep oil reservoirs.