Improved Methods for Water Shutoff – 1997

R.S. Seright – 1997

Abstract

Second year of the water shutoff project, covering three advances. WOR (water/oil ratio) diagnostic plots are shown to be unreliable as standalone diagnostic tools — channeling and coning signatures easily overlap in simulation. An 11-step engineering procedure with GUI software provides a sound basis for sizing gelant treatments in hydraulically fractured production wells. For naturally fractured reservoirs, gel treatments are most promising when R-values (aligned to non-aligned fracture conductivity ratio) exceed 10, and when produced tracer concentrations exceed 30 percent of injected concentration. Tracer transit times are useful for estimating fracture conductivity but insensitive to R- and n-values.

Key Takeaways

  • WOR diagnostic plots are unreliable as standalone diagnostic tools — multi-layer channeling and bottom-water coning can generate indistinguishable WOR signatures in simulation.
  • An 11-step procedure with GUI software provides a sound engineering basis for sizing gelant treatments in hydraulically fractured production wells, ending the era of strictly empirical design.
  • Gel treatments in naturally fractured reservoirs show greatest promise when the R-value (aligned to non-aligned fracture conductivity ratio) exceeds 10.
  • Produced tracer concentrations above 30 percent of the injected value are a practical indicator that gel treatment potential is high in a given naturally fractured well.
  • Tracer transit times are insensitive to R- and n-values, making them most useful for estimating fracture conductivity rather than assessing gel treatment potential directly.
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