Injection of polymer for improved sweep efficiency in high temperature high salinity carbonate reservoirs: Linear X-ray aided flood front monitoring

Polymer flooding is one of the most commonly used techniques to improve oil recovery; however its application is dependent on the technical and economic feasibility along with the knowledge of the risks involved. The presented work is focused on quantifying the uncertainties affecting the mobility of injected fluid in polymer flooding along with a sensitivity analysis of influential parameters. Initially, a coreflooding experiment on carbonate core sample is performed using partially hydrolyzed polyacrylamide, SAV 10 under high temperature high salinity conditions. The coreflood apparatus is aided with linear X-ray in order to record real time saturations for the entire length of core sample in addition to the pressure and production data. The experimental data are then history matched using commercial software to generate relative permeability curves and to optimize polymer slug size and initiation time. The optimized model is then used as a reference and a coredflood is conducted on the optimized conditions i.e. slug size and initiation time. The recovery obtained from the experimental run is compared with the simulation results. Polymer viscosity, adsorption on the rock surface and mechanical degradation are some of the other parameters included in the study. The optimum polymer flooding scenario established in this study is injection of 0.1 PV of polymer after 0.3 PV water injection. Encouraging results are obtained at the optimized conditions resulting in an overall recovery factor of 84% and early injection of polymer also helped to delay the breakthrough time. The small slug size resulted in low adsorption and residual residual factor for the optimized case is found to be 1.73.