Rheological Behaviour and Hydrodynamic Diameter of High Molecular Weight, Partially Hydrolyzed Poly(acrylamide) in High Salinity and Temperature Conditions

Abstract

ABSTRACT Key Words: Rheological Behaviour and Hydrodynamic Diameterof High Molecular Weight, Partially HydrolyzedPoly(acrylamide) in High Salinity and Temperature Conditions Ahmad Ramazani Saadatabadi 1* , Meysam Nourani 1 , and Mohammad Ali Emadi 2 (1) Chemical and Petroleum Engineering Faculty, Sharif University of Technology, P.O. Box: 11365-9465, Tehran, Iran (2) Department of Research and Technology, National Iranian Oil Company, P.O. Box: 196981-3771, Tehran, IranReceived 13 May 2009; accepted 1 February 2010 T he intrinsic viscosity of high molecular weight-partially hydrolyzed poly(acry-lamide) which is mainly used in enhanced oil recovery (EOR) processes hasbeen investigated in reservoir conditions. Since, the EOR efficiency of hydrolyzedpoly(acrylamide) is very sensitive to the temperature and salinity of petroleum reservoirs, investigations have been carried out at different possible reservoir temperatures using high saline polymer solutions. Non-linear relationships betweenreduced viscosities and polymer concentrations were observed at low polymer concentrations. Plotting the relative viscosity variation versus polymer concentration insemi-logarithmic scale was used to calculate the intrinsic viscosity. Furthermore, thecritical concentration was calculated which could be helpful in determination of the optimized polymer concentration to introduce into the reservoir. Moreover, the effectsof temperature and salt concentration are studied on the Mark-Houwink-Sakuradaparameters and hydrodynamic molecular diameter. Zero-specific-viscosity which is thespecific viscosity at zero polymer concentration is introduced, to find out whether a zerovalue is obtained at zero polymer concentration. However, experimental observationsshow that the specific viscosity is not zero at zero polymer concentration for highmolecular weight-partially hydrolyzed poly(acrylamide). In this work, an empirical correlation is developed to relate zero-specific-viscosity and the hydrodynamic diameter of polymer molecule.