Using Chemicals to Optimize Conformance Control in Fractured Reservoirs – 1999

R.S. Seright – 1999

Abstract

First year of a new conformance optimization project. Gel propagation through fractures is characterized: gel permeability correlates with polymer concentration to a power between -2.5 and -3.0. Higher-molecular-weight HPAM (Percol 338) achieves similar or better extrusion behavior at 2.5 times lower polymer and chromium concentrations — a significant cost advantage. Gelant treatment sizing software is updated to Version 1.07, improving low-water-cut handling and input modification. Field experience confirms that accurate current reservoir pressure data is essential for the sizing software. Gel rheology is characterized — elastic modulus greatly exceeds viscous modulus, consistent with ease of fracture extrusion. Disproportionate permeability reduction studies continue.

Key Takeaways

  • Gel permeability in fractures correlates with polymer concentration raised to a power between -2.5 and -3.0 — providing a quantitative tool to predict post-treatment fracture conductivity.
  • Higher-molecular-weight HPAM (Percol 338) achieves similar or better gel extrusion behavior at 2.5 times lower polymer and chromium concentrations — a significant treatment cost reduction.
  • Gelant treatment sizing software Version 1.07 improves handling of low-water-cut wells and allows input modification without restarting calculations.
  • Field experience confirms that outdated reservoir pressure estimates can incorrectly classify good gel treatment candidates as unsuitable — current pressure data is essential.
  • For 24-hour-old Cr(III)-acetate-HPAM gels, the elastic modulus greatly exceeds the viscous modulus — consistent with the relatively easy extrusion of these gels through fractures.
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