Gel Water Shutoff in Fractured or Faulted Horizontal Wells

R.H. Lane, R.S. Seright – 2000

Abstract

This paper describes advances in design and implementation of polymer gel water shutoff treatments in horizontal wells penetrating fractures or faults. Simple calculations using injectivity data before and during gel injection can indicate fracture width. Combining laboratory gel data with field measurements before, during, and after gel injection estimates actual gel penetration depth into the fracture. A detailed case history is presented along with summaries of several other treatments. Critical field measurements needed during treatment and directions for additional laboratory work to improve design are identified.

Key Takeaways

  • Simple fracture width calculations using injectivity data before and during gel injection provide a first-order estimate of the fracture aperture causing water production — a critical sizing input unavailable from standard well data alone.
  • Laboratory gel residual resistance factor data combined with field pressure and rate measurements before/during/after treatment can estimate actual gel penetration depth into the fracture — enabling post-treatment calibration.
  • Horizontal wells penetrating fractures present unique gel placement challenges: multiple fracture intersections, gravity segregation of gel along the horizontal section, and variable fracture aperture all complicate volume and placement design.
  • Critical field measurements for fractured horizontal well gel treatments include bottomhole pressure at all stages, produced water salinity, and tracers — these data enable fracture characterization and treatment analysis.
  • Synergy between monitored field treatments and laboratory research drives improvement — field observations identify unexpected behavior, while laboratory data provide mechanistic explanations that improve subsequent designs.
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