Polymer Retention “Tailing” Phenomenon Associated with the Milne Point Polymer Flood

Abstract

This paper explores the unusual shape of HPAM breakout/propagation during dynamic polymer retention measurements in Milne Point core material. In contrast to conventional expectations, polymer retention does not delay initial polymer bank arrival, but after effluent concentration rapidly rises to at least 50% of injected value, the concentration gradually tails up over many pore volumes before reaching the injected value. Wide-ranging experiments varied polymer concentration, molecular weight, core length, preservation state, sand grain size, and mineral composition. Illite is identified as primarily responsible for the tailing phenomenon. The effect was observed in cores with illite but not in packs of other minerals including kaolinite, montmorillonite, chlorite, calcium carbonate, dolomite, siderite, pyrite, or calcium sulfate. A model is proposed to account for tailing, with implications for projecting field polymer flood performance. Mineralogy analysis (especially illite and kaolinite) may reveal whether tailing should be incorporated into polymer flood simulations.

Key Takeaways

  • HPAM polymer retention in illite-bearing Milne Point core material does not delay initial polymer bank arrival — instead, the bank arrives quickly but at only 50–70% of injected concentration, then gradually tails up to full concentration over many pore volumes.
  • Illite is the mineral specifically responsible for the tailing phenomenon — the effect was observed consistently in illite-bearing cores but not in packs of kaolinite, montmorillonite, chlorite, calcium carbonate, dolomite, siderite, pyrite, or calcium sulfate.
  • The tailing behavior is insensitive to flow rate, polymer concentration, molecular weight, core length, core permeability, heterogeneity, and preservation state — it is a robust property of the illite-HPAM interaction rather than an experimental artifact.
  • A mechanistic model for the tailing phenomenon is proposed and validated against the experimental dataset, providing a simulator-ready implementation for projecting polymer flood performance in illite-bearing formations.
  • Mineralogy analysis (specifically XRD quantification of illite content) is recommended as a screening tool to identify whether tailing should be incorporated into polymer flood simulations for a given reservoir.
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