Gel Diverters
Gel-type diverting agents are available in both temporary and permanent forms.
Temporary Gels:
Temporary gels are used during acidizing or fracturing treatments that call for diverting or blocking action. They are commonly used in previously acidized or fractured wells, with side permeability differences, that benefit more from multiple than single extended fractures or flow channels.
Temporary gels are either oil- or water-base mixtures. They are usually pumped into the formation as relatively thin fluids which set up quickly to form a semi-solid or thick gel that prevents additional fluid from entering the zone. After a predetermined time the gel breaks, reverting to a water-thin liquid that is easily produced from the well.
Diversion of a pregravel-pack acid treatment can be accomplished with 5 bbl batches of gel led 3% NH4Cl plus 100 lb. of correctly sized gravel-pack sand. The combination of viscosity and particles diverts treating fluid to other perforations.
Permanent Gels:
Permanent blocking gels are especially useful for blocking within the formation. On the surface they are thin, true solutions of low viscosity that can penetrate any water-permeable formation. Once in place within the formation, they solidify into a rigid, permanent gel that does not break.
Permanent gels are designed to
- alter the injection profile of water-injection wells
- shut off water zone encountered in air drilled wells
- plug lost circulation zones
