Rheological properties of new polymer compositions for sand consolidation and water shutoff in oil wells

Abstract

The rheological properties of some newly developed polymer compositions have been investigated with and without crosslinking. These polymer compositions were developed as a water shutoff and sand consolidation treatment agents for producing oil and gas wells. The effects of several variables on the rheology of the compositions were evaluated over a wide range of temperatures (25–110°C), shear rates (0–500 s−1), brine percentages (0–15%), crosslinker types and concentrations (0–3%), and polymer concentrations (6–50%). It was found that increasing the shear rate from 0 s−1 to 100 s−1 caused shear thinning and reduction of the viscosity of the dilute solutions (6–13%) from 25 cP to ∼ 3 cP at 80°C. In contrast, for the concentrated solutions (20–50%), the viscosity dropped slightly in the shear rate range 0–10 s−1, and subsequently decreased more slowly up to shear rates of 500 s−1. The viscosities of all polymer solutions dropped by a factor of 2 as the brine concentration increased from 0% to 15%. Finally, aging time coupled with shear rates and higher percentages of crosslinkers accelerate the buildup of viscosity and gelation time of the polymer compositions. For concentrated solutions, shear rates ranging within 0–200 s−1 accelerated gelation time from 9.75 h to 2–3 h, when they were sheared at 80°C. The polymeric solutions exhibited Newtonian, shear-thinning (pseudo-plastic), and shear-thickening (dilatant) behavior, depending on the concentration, shear rate, and other constituents. In most cases, the rheological behavior could be described by the power law. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007