Application of organic cross-linked gel system for mitigating CO2 leakage from high temperature reservoirs

This study aims to mitigate CO 2 leakage in high-temperature reservoirs using an organic cross-linked gel system. The engineered fluid system was evaluated by a quantified rheological methodology and pore-plugging analysis. A sulfonated hydrolyzed polyacrylamide polymer and organic crosslinkers, hydroquinone and hexamethylenetetramine, were utilized for forming the fluid gel systems. The pressure cell assembly has been employed for the gel analysis at an elevated temperature of 110 o C under a pressurized CO 2 environment. The high-temperature viscosity vs. aging time data acquired under continuous shear conditions ( 50 s -1 ) was ingeniously categorized into three regimes: (i) an induction period characterized by a lower linear slope of dμ/dt = 15-50 mPa·s/hr . (ii) a 'non-linear' transition regime (iii) a rapid cross-linking period characterized by a higher linear slope, i.e. dμ/dt ≥350 mPa.s/hr . The ‘gelation time’, defined as the point of initiation of the rapid-crosslinking period, was successfully modelled for variations in polymer concentration utilizing first-order kinetics. The new outcomes of the high-temperature rheological investigation under the pressurized CO 2 environment were compared with the traditional bottle-testing approach and oscillatory rheological studies. The core flooding results showed excellent plugging efficiency (>99%) for both sub-critical and super-critical CO 2 injections beyond the 'gelation time' at 110 °C.