| INJECTOR-PRODUCER CHANNELING IN UNFRACTURED RESERVOIRS WITH CROSSFLOW (PROBLEM 13 IN TABLE
1) |
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| 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. |
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