Laboratory evaluation of high-temperature resistant lysine-based polymer Gel systems for leakage control

In-situ crosslinking gel known for its cost-effectiveness, has been employed for decades to plug high-permeability features in subsurface environments. However, some commonly used crosslinkers are being phased out due to the increasingly rigorous environmental regulations. As a newly discovered environmentally friendly crosslinker, lysine can crosslink the partially hydrolyzed polyacrylamide through transamidation reaction. The present work aimed to study the effect of polymer composition and concentration on the gelation behavior of lysine and high molecular weight acrylamide-based polymers. Several commercial high molecular weight polymers with different contents of 2-Acrylamido-2-methyl-1-propane sulfonic acid (AMPS) including AN -105/125, SAV-55/ 37/28, and SAV-10 were deployed in this work. High-temperature/pressure-resistant glass tubes were used to study the crosslinking behavior. The plugging efficiency test used a high permeability sandstone core (1600 mD). Besides, the effect of salinity and pH on the crosslinking behavior, gel strength, and long-term thermal stability was also studied. Results showed that increasing the AMPS content could prolong the gelation time, but the polymer and lysine mixture failed to form gels when the AMPS content was excessively high. Additionally, increasing the AMPS content negatively affects the gel strength but positively impacts long-term thermal stability. Polymer gel with a relatively high content of AMPS could be stable in 0.5 % CaCl2 solution at 130 degrees C for over 200 days. The polymer/lysine gel system can efficiently plug the high permeability matrix, and the plugging efficiency is higher than 99 %. The polymer/lysine gel system is a promising green leakage control system in treating the high conductivity features in geothermal and oil reservoirs.