A new method to evaluate elasticity of polymers based on elasticity-recovery experiment

摘要

It has been long believed that the elastic nature of the polymer is equally important to the viscous property and some people even suggest that elasticity is the dominant force contributing to the additional reduction in oil saturation. But until now, there is still no widely accepted method of evaluating the elasticity of polymers. So, the objective of this paper is just to make an attempt to develop a simple but practical elasticity evaluation method for polymers. Three common used polymers, comb polymer (KYPAM-2), hydro-polyacrylamide (MO-4000) and hydrophobically associating polymers (HTPW) were selected as the research objects and the new method was established based on an elasticity-recovery experiment. The elasticity was characterized in terms of elasticity retention rate, which was the ratio of G' (storage modulus) value of post-sheared to that of pre-sheared for polymer solutions. This method can reflect the variation of elasticity of polymers after sheared in formation, and solved the problem that the elasticity of MO-4000 and HTPW can not be distinguished only by the value of G' and the platform of G'. In addition, this new method is not acted on the polymer concentration. Results showed that the elasticity of these selected three polymers decreased in the following sequence: KYPAM-2 > MO-4000 > HTPW. Core displacement and visual microscopic displacement experiments both proved that the higher the elasticity behavior was, the higher the oil recovery was. So the oil recovery of these three polymers decreased also in the following order: KYPAM-2 > MO-4000 > HTPW. (C) 2016 Elsevier B.V. All rights reserved.