Synthesis and properties of elevated temperature hydrogels for enhanced oil recovery based on AM/AMPA/NVP copolymer and silica nanoparticles

Abstract

AbstractTo improve the stability of polymer gel profile control agents used in high‐temperature and high‐salinity reservoirs, the temperature‐resistant and salinity‐resistant polymer (TSP) was synthesized from acrylamide (AM), 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS), N‐vinyl‐2‐pyrrolidone (NVP) via free radical polymerization reaction using initiator. The TSP showed excellent salt resistance and thermal stability because of the introduction of the sulfonic acid group, hydrophobic group, and rigid group. Furthermore, a novel elevated temperature hydrogel (ETG) for profile control was prepared using TSP, a crosslinker hexamethylenetetramine‐hydroquinone (HMTA‐HQE), and silica nanoparticles as an enhancer. The formula of ETG was as follows: 0.5 wt% TSP + 0.3 wt% HMTA‐HQE + 0.2 wt% silica nanoparticles (enhancer). SEM and FTIR analyzed the micromorphology and composition of ETG. Under high temperature and salinity (110°C, 85702 mg/L), the apparent viscosity of ETG reached up to 3 × 104 mPa·s, and controllable gelation time was 10–20 h. After aging for 120 days at 110°C, the viscosity retention rate was more than 75%, indicating ETG had better thermal stability. Moreover, the plugging ratio of ETG reached up to 97.8%, while the plugging ratio of the conventional HPAM hydrogel was only 81.2%, which indicated that ETG also had good plugging performance.