Effective Propagation of HPAM Solutions Through the Tambaredjo Reservoir During a Polymer Flood

R.N. Manichand, K.P. Moe Soe Let, L. Gil, B. Quillien, R.S. Seright – 2013

Abstract

Two new methods were developed for anaerobically sampling polymer solutions from production wells during the Sarah Maria polymer-flood pilot in Suriname’s Tambaredjo field. Previous methods indicated severe polymer degradation; the improved methods revealed that polymer propagated intact more than 300 ft through the Tambaredjo formation. Analysis of produced salinity, polymer concentration, and viscosity indicated that polymer banks retained low salinity and high viscosity for much of their transit. Strong shear-thickening rheology was observed in porous media for 1,000 and 1,350 ppm HPAM at only 500 ppm TDS. Injectivity analysis revealed injection above the formation parting pressure, with fractures propagating only approximately 20 ft — small enough not to jeopardize sweep efficiency, but large enough to greatly improve polymer injectivity and reduce concerns about mechanical degradation.

Key Takeaways

  • HPAM polymer propagated intact for more than 300 ft through the Tambaredjo reservoir — far more than previous severely degraded production samples suggested, resolving a major inconsistency between production response and produced polymer quality data.
  • Improved anaerobic sampling methods are critical: previous methods that indicated severe HPAM degradation in production wells were sampling artifacts caused by oxidative degradation during sample collection, not actual in-situ degradation.
  • Produced salinity and polymer concentration monitoring showed that polymer banks retained low salinity and high viscosity throughout much of their reservoir transit — consistent with piston-like displacement in some zones.
  • Strong shear-thickening rheology was observed in porous media for 1,000–1,350 ppm HPAM at only 500 ppm TDS — confirming that near-wellbore pressure drops may be substantially higher than viscometer predictions suggest.
  • Fractures at Tambaredjo propagated only approximately 20 ft — small enough to preserve sweep efficiency but large enough to dramatically improve polymer injectivity and protect against mechanical degradation in the near-wellbore zone.
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