Injector-Producer Channelling in Unfractured Reservoirs with Crossflow
Problems 13 in Table 1

Gelant and gel treatments are expected to be ineffective for treating injector-producer channeling in unfractured reservoirs where fluids can crossflow between zones.22 For many years, engineers recognized that near wellbore blocking agents are ineffective in these applications.73 Even if the blocking agent could be confined only to the high permeability channel, water quickly cross flows around any relatively small plug. The only hope for blocking agents in these applications exists if a very large plug (i.e., that plugs most of the channel) can be selectively placed only in the high permeability zone.73 Unfortunately, existing gelants (including the so-called “colloidal dispersion gels”) enter and damage all open zones in accordance with the Darcy equation and basic reservoir engineering principles.22 Penetration and damage caused to the less-permeable zones is greater for viscous gelants than for low-viscosity fluids. Also, penetration and damage caused to the less-permeable zones is greater when crossflow can occur than when crossflow cannot occur.22 Although an admirable attempt was made to devise a sophisticated process where gelant treatments might be effective in treating this type of problem,74,75 traditional polymer floods provide a more cost-effective and reliable solution.22,76-79 Refs. 76-79 provide illustrative examples of polymer floods in various fields throughout the world.