Polymer flooding and its effects on enhanced oil recovery special reference to Upper Assam Basin

Abstract

Chemical Enhance oil Recovery (CEOR) technology is getting more attention since energy crises are getting worse and frightened. Successful application of polymer flooding depends on the evaluation of rheological and solution properties of injected slug at reservoir conditions, which is function of polymer concentration, salinity, temperature and shear rate. Poly acryl amide (PAM) is commonly used polymer in polymer flooding technique. However, comparative study with other polymers such as xanthan gum (XG) is required while selection of appropriate polymer for CEOR. In present study, the recovery efficiency of PAM and XG as a polymer has been evaluated for application as chemical EOR agent for tertiary phase polymer flooding in Upper Assam basin. The comparative study between PAM and XG has been done in terms of rheological properties. Core flooding experiment of polymer flooding has also been tested to determine the recovery efficiency of the PAM and XG polymer solutions. The results showed that these polymers exhibit favorable salt tolerance, temperature resistance, and recoverable viscosity after shearing, reasonable thickening behavior and improved viscosity enhancement properties due to presence of hydrophobic association in the polymer main chains. Core flooding experiment of polymer flooding has also been tested to determine the recovery efficiency of the PAM and XG polymer solutions. Results show that macroscopic sweep efficiency is the dominant factor during recovery. While an injection of hydrogel polymer to the reservoir is to increase a viscosity of fluid containing water so that the fluid is more difficult to flow than the oil, and as a result, the oil production increases. Shear thinning behavior was observed in case of PAM indicating predominance of the frontal advance theory. As PAM seems to be following both piston like movement and frontal advance theory it can be efficiently enhancing the macroscopic sweep efficiency as well as microscopic displacement efficiency. The overall recovery efficiency of 53% of OOIP was determined for PAM flooding. The overall recovery efficiency by XG polymer flooding was found to be 45%, signifying its lesser efficiency in comparison to PAM. Success of the projects also depends on cost analysis. Simulation by Computer Modelling Group (CMG) study has also been carried out to validate the experimental findings.