Synthesis and assessment of a hydrophobically associating heteropolymer in water-based mud

Abstract

Water-soluble polymers can be used as key ingredients of both drilling fluids for virgin fields and polymer-enhanced oil recovery in underperforming reservoirs. The efficacy of hydrophobically associating heteropolymer (HAH-Polymer) as an agent for petroleum resource recovery was examined in this study. The hydrophobically associating heteropolymer (HAH-Polymer) comprising acrylamide, sodium 2-acrylamido-2-methylpropanesulfonate, hydroxyethyl methacrylate and lauryl methacrylate was synthesized in micellar medium by free-radical polymerization. The hydrophobically associating heteropolymer (HAH-Polymer) was characterised by FTIR and 1H NMR spectral analyses. The effects of temperature, pH and shear on the solution behavior of the HAH-Polymer were also examined. Rheological and fluid loss properties of HAH-Polymer-incorporated water-based drilling fluids were assessed. The HAH-Polymer improved the thermal stability between 25 and 160 °C of the drilling mud and maintained mud fluid loss of 8.4–8.6 cm3 compared with the polymer-free blank of 43.5–107.0cm3. In a salt-contaminated mud, the heteropolymer enhanced rheological properties and significantly reduced API filtration loss to 7.6–8.8 cm3 after hot aging between 25 and 150 °C. Under high temperature–high pressure filtration testing of muds, the HAH-Polymer demonstrated excellent fluid loss reduction by providing about eightfold fluid loss control (14.7 cm3) compared to the polymer-free blank (113.2 cm3) at 150 °C.