Aperture Tolerant Chemical Based Methods To Reduce Channeling – 2005

R.S. Seright – 2005

Abstract

First year of the aperture-tolerant channeling reduction project. Simulation studies assess optimal gel plug placement in fractured reservoirs under four well-fracture scenarios. For fracture widths of 0.25 mm or less in 100-md rock, channeling is not a problem. For wider fractures, at least 10 percent (ideally more than 20 percent) of the fracture must be plugged, centered, to significantly improve sweep. Near-wellbore plugs alone reduce channeling rates but do not improve matrix sweep. Low-concentration gels (0.2 to 0.25 percent HPAM) can plug 0.1-mm fractures but fail for 0.5-mm or wider fractures. Strong pore-filling gels consistently reduce water permeability to about 0.24 md regardless of initial permeability (120 to 6500 md).

Key Takeaways

  • For fractures 0.25 mm wide or narrower in 100-md rock, channeling is not a problem and gel plugs are not needed; for fractures wider than 0.5 mm, gel plugs are justified.
  • Meaningful sweep improvement requires plugging at least 10 percent of the offending fracture length (ideally more than 20 percent), with the plug centered — near-wellbore plugs alone do not improve deep matrix sweep.
  • Low-concentration gels (0.2 to 0.25 percent HPAM) can effectively plug 0.1-mm fractures but fail for 0.5-mm and wider fractures — these compositions do not yet meet the aperture-tolerant goal.
  • Strong pore-filling Cr(III)-acetate-HPAM gels (0.5 percent HPAM) consistently reduce water permeability to approximately 0.24 md across initial permeabilities from 120 to 6500 md.
  • With sufficient oil throughput, pore-filling gels dehydrate to achieve Frro of 2 or less — potentially applicable to production well DPR treatment without zone isolation.
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