When gel treatments are applied to treat coning problems, a common misconception is that the gelant will only enter the water zones at the bottom of the well. In reality, this situation will occur only if the oil is extremely viscous and/or the aqueous gelant is injected at an extremely low rate (to exploit gravity during gelant placement).17,18,25 In the majority of field applications to date, the crude oils were not particularly viscous, and gelant injection rates were relatively high.10,2 For the reasons explained in the previous section, in three-dimensional (3-D) coning applications, one must be concerned about damage that polymer or gel treatments cause to hydrocarbon-productive zones.
Even if a polymer or gel reduces kw without affecting ko, gel treatments have limited utility in treating 3-D coning problems. Extensive numerical studies using a variety of coning models indicate that gel treatments can only provide improvement if the desired production rate is less than 1.5 to 5 times the pretreatment critical rate.25 This circumstance rarely occurs.