Experiment and application of movable gel prepared by recycled produced water

Abstract Cations such as Ca2+, Mg2+, Fe2+ etc. in recycled produced water seriously affect the viscosity and stability of movable gel. Four types of polymers were evaluated in laboratory including comb-shape polymer and hydrophobically associating polymer. By analyzing two types of polymers’ molecular structures, it showed that comb-shape polymer was easier to improve its properties by cross-linking reaction, and the viscosity of the hydrophobically associating polymer mostly came from the viscosity of molecular structure. Cross-linking reaction contributed little to the viscosity of hydrophobically associating polymer. The movable gel was prepared in salt water of TDS=2.64×104mg/L by using comb-shape polymer B and modified phenolic resin prepolymer. By introducing rigid benzene ring structure, the salt tolerance and long-term stability were significantly improved. The viscosity of retain rate was more than 70% after 60d under 90°C. Field application of 3 wells showed that qualification rate of preparing movable gel was 100% and oil increment was 3020t.