Researchers at The Institute of Petroleum Engineering at TU Clausthal in Germany are being supported by Malvern Instruments in new work to understand and optimize the performance of Enhanced Oil Recovery (EOR) fluids. The polymeric solutions used for EOR exemplify the fluids used in a range of drilling applications to maximize oil extraction while at the same time safeguarding geological formations.
EOR involves injecting a solution into the porous rock surrounding a well and can boost the amount of oil extracted by up to 20%. The fluids used are relatively concentrated solutions of high molecular weight polymers and have interesting flow behavior. The new research demonstrates the ability of the Kinexus rheometer from Malvern to measure the viscous (liquid-like) and elastic (solid-like) responses of EOR fluids in order to characterize and predict how they will perform under the conditions likely to be encountered during use.
The resulting data enable rationalization of the behavior of EOR fluids in porous media. In use these fluids must accelerate and decelerate as they traverse pores through narrow connecting channels. This generates stretching or extensional forces along the flow axis due to their viscoelastic characteristics, while at the same time fluid close to the walls is subjected to shear forces. Viscoelastic fluids demonstrating such behavior have been shown to improve displacement efficiency and recovery yields compared with conventional Newtonian fluids.
EOR fluids must therefore be formulated to exhibit optimum viscoelastic behavior and resistance to stretching, a feature that can be investigated directly by rheological characterization. Furthermore, the research shows how a range of complementary methods accessible via the Kinexus can be applied to gain valuable insight into the effect of concentration, temperature and brine reservoir hardness on fluid performance. The resulting data support the safe and effective use of these commercially valuable industrial fluids.