Polymer Solution Preparation, Quality Control, and Produced Fluid Analysis at Milne Point

Abstract

Summary This paper focuses on solution preparation and quality control activities associated with the Milne Point polymer flood on the North Slope of Alaska. This project uses 10 different polymer injection locations with a variety of skid types and configurations, which had a notable impact on polymer quality control and dissolution operations. Compared with bulk 500-kg to 750-kg polymer bags, silos greatly improved the storage capacity and increased the overall quality of the polymer solutions. Silos required less physical effort when transferring polymer. Polymer hydration skids that were made in-house by the polymer supplier were more reliable and experienced fewer polymer solution quality and startup issues than those that were outsourced. These in-house skids also used a uniform programming software that made it relatively easy to train the operators on new hydration skids. For pumping polymer mother solution, triplex pumps provided the best runtime and were most maintenance-friendly, compared with diaphragm or triple screw pumps. Because of the soluble iron present in the polymer makeup water, nitrogen blanketing was preferred to minimize corrosion and oxidative degradation. Inline static mixers were ineffective in mixing mother solution with dilution water when the mixing occurred close to the wellhead. Mixing the two streams too close to the wellhead led to substantial variations in wellhead viscosity measurements. Dedicating individual pumps for injection into a given well provided desirable flexibility in controlling rates and concentrations of polymer for the well. Monitoring produced salinity and polymer concentration provided useful insights about improved sweep and polymer retention associated with the polymer flood. The observed field behavior was consistent with laboratory studies, indicating a “tailing” phenomenon associated with polymer retention at Milne Point.