Is Polymer Retention Different Under Anaerobic vs. Aerobic Conditions?

This paper examines whether HPAM retention differs under anaerobic vs. aerobic conditions, using both static (mixing with loose sand) and dynamic (coreflood) methods. On pure silica sand or Berea sandstone, polymer adsorption values are small with little aerobic/anaerobic difference. HPAM retention increases significantly with pyrite or siderite content. Under aerobic conditions, retention with iron minerals can be twice that measured anaerobically — because viscosity-based polymer detection under aerobic conditions overestimates retention through oxidative degradation. For pyrite-bearing samples, HPAM retention was significantly lower anaerobically; for siderite, aerobic/anaerobic conditions showed less difference. Under aerobic dynamic conditions, higher flow rates underestimate retention (211 mg/g at 6 ft/d vs. 43.2 mg/g at 30 ft/d with 10% pyrite); under anaerobic conditions, retention was consistent across flow rates (40.6–47.8 mg/g at 6–33 ft/d). If iron minerals are present, anaerobic conditions provide the most representative retention measurements.