Gel Placement in Production Wells

Jenn-Tai Liang, R.L. Lee, and R.S. Seright – 1993

Abstract

Fractional flow theory and material-balance calculations demonstrate that, if zones are not isolated during gel placement in production wells, gelant can penetrate significantly into all open zones — not just those with high water saturations. Unless oil saturations in oil-productive zones are extremely high, oil productivity will be damaged even if the gel reduces water permeability without affecting oil permeability. Capillary pressure does not prevent gelant penetration into oil-productive zones in field applications. An explanation is provided for the occurrence of successful gel applications in fractured wells produced by bottomwater drive. With the right properties, gels could significantly increase the critical rate for water influx in fractured bottomwater-drive wells.

Key Takeaways

  • Fractional flow theory shows that gelant penetrates significantly into all production well zones — not just high-water-saturation zones — if zones are not isolated during gel placement.
  • Oil productivity will be damaged by gelant invasion unless oil saturations in oil-productive zones are extremely high — the commonly hoped-for selective damage to only water-producing zones does not occur without isolation.
  • Capillary pressure does not prevent gelant penetration into oil-productive zones in field applications — this common assumption is incorrect, and treatment designs that rely on it will be incorrect.
  • Successful gel applications in fractured wells produced by bottomwater drive can be explained by the linear flow geometry toward the fracture, which concentrates gel at the fracture-bottomwater interface rather than in the rock matrix.
  • Gels with the right properties can significantly increase the critical rate for water influx in fractured bottomwater-drive wells — providing a mechanistically sound basis for gel application in this well type.
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