Gel Treatments for Reducing Channeling in Naturally Fractured Reservoirs

R.S. Seright and R.L. Lee – 1999

Abstract

This paper examines reservoir variables that affect the severity of channeling and the potential of gel treatments for reducing channeling through naturally fractured reservoirs. Tracer and gel placement studies were performed with two different simulators. Gel treatments have the greatest potential when fractures aligned with direct flow between injector-producer pair have conductivities at least 10 times greater than off-trend fractures. Gel treatments also have the greatest potential in reservoirs with moderate to large fracture spacing. Tracer transit times from interwell tracer studies can estimate the conductivity of the most direct fracture. Gel treatment effectiveness is insensitive to fracture spacing for on-trend fractures but increases with increased fracture spacing for off-trend fractures.

Key Takeaways

  • Gel treatments have the greatest potential in naturally fractured reservoirs when on-trend fractures (aligned with direct injector-producer flow) have conductivities at least 10 times greater than off-trend fractures.
  • Gel treatments also have the greatest potential in reservoirs with moderate to large fracture spacing — small fracture spacing reduces treatment effectiveness by providing many parallel flow paths that require blocking.
  • Interwell tracer transit times from tracer studies can be used to estimate the conductivity of the most direct fracture — providing a diagnostic tool for predicting gel treatment candidacy before committing to a treatment.
  • Gel treatment effectiveness is insensitive to fracture spacing for fractures aligned with the direct flow direction (on-trend), but increases with fracture spacing for fractures not aligned with direct flow (off-trend).
  • Produced tracer concentrations from interwell tracer studies can help identify reservoirs that are predisposed to successful gel applications — making tracer tests a valuable pre-screening tool for naturally fractured reservoir gel programs.
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