Aperture Tolerant Chemical Based Methods To Reduce Channeling – 2006

R.S. Seright – 2006

Abstract

Second year of the aperture-tolerant project, covering five topics: DPR optimization with strong pore-filling gels; RPM/DPR treatment guidelines for production wells; correlation of gel rheology with fracture extrusion behavior; sweep improvement options for Daqing Oil Field; and assessment of colloidal dispersion gels (CDGs) and foams. Strong pore-filling gels overcome three key DPR limitations of weak gels. RPM/DPR treatments are applicable to a narrow range of well conditions. The pressure gradient for gel extrusion varies inversely with the square of fracture width — linked to mobile gel wormhole width being much narrower than total fracture width. CDGs provide no significant sweep improvement beyond a standard polymer flood in the Daqing system studied.

Key Takeaways

  • Strong pore-filling Cr(III)-acetate-HPAM gels overcome three DPR limitations of weak gels: variable performance, Frro greater than 2 in radial flow, and permeability-dependent behavior.
  • RPM/DPR treatments are suitable for a narrow range of production well conditions — fully drawn-down wells with separate oil and water zones; for most other scenarios, economics are marginal.
  • Pressure gradient for gel extrusion varies inversely with the square of fracture width because mobile gel wormhole width is much narrower than the overall fracture aperture — shell momentum balance models explain this.
  • Colloidal dispersion gels (CDGs) provide no statistically significant sweep improvement beyond that of a standard polymer flood in the high-permeability polymer-flooded Daqing reservoir studied.
  • For future ASP flooding at Daqing, mobility control will be especially challenging — foams remain an option but face placement and stability challenges similar to polymer-flooding scenarios.
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