Method of enhancing fracture conductivity
AssigneeBaker Hughes Incorporated
InventorsHarold Dean Brannon, Brian N. Ward
Life of this patent
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Abstract
The method disclosed herein includes the introduction of proppant-free stage and a proppant laden stage into the wellbore and/or subterranean formation. The method increases the effective fracture width and enhances fracture conductivity within the formation. Either the proppant-free stage or the proppant laden stage contains a breaker. The other stage contains a viscosifying polymer or viscoelastic surfactant to which the breaker has affinity. The proppant-free stage may be introduced prior to introduction of the proppant laden stage into the wellbore and/or formation. Alternatively, the proppant laden stage may be introduced into the wellbore and/or formation prior to introduction of the proppant-free stage.
Claims25
A method of hydraulically fracturing a subterranean formation comprising:
- (a) pumping into the formation at least two stages wherein a first stage is a proppant-free fluid and a second stage is a proppant laden slurry and further wherein one of the stages contains a first viscosifying polymer and a crosslinking agent and the other stage contains a breaker and optionally a second viscosifying polymer, viscoelastic surfactant and/or friction reduction agent;
- and
- (b) degrading the first viscosifying polymer with the breaker wherein the breaker has greater affinity for the first viscosifying polymer than the optional second viscosifying polymer, viscoelastic surfactant and/or friction reduction agent which may be present in the stage containing the breaker;
- and
- further wherein (i) the first viscosifying polymer is selected from the group consisting of cellulose, cellulose derivatives, starch, starch derivatives, xanthan, derivatized xanthan and mixtures thereof;
- and (ii) the crosslinking agent contains a metal selected from the group consisting of aluminum, antimony, zirconium and titanium.
A method of hydraulically fracturing a subterranean formation comprising pumping into the formation at least two stages wherein either:
- (a) the first stage is a proppant laden slurry and contains at least one viscosifying polymer and at least one crosslinking agent and the second stage is free of proppant and contains a breaker and, optionally a viscoelastic surfactant and/or friction reduction polymer;
- or
- (b) the first stage is free of proppant and contains at least one viscosifying polymer and at least one crosslinking agent and the second stage is a proppant laden slurry which contains a breaker and at least one member selected from the group consisting of viscoelastic surfactants and friction reduction polymers
- wherein the breaker has greater affinity for the at least one viscosifying polymer than the viscoelastic surfactant and/or friction reduction polymer and further wherein:
- (i) the first viscosifying polymer is selected from the group consisting of cellulose, cellulose derivatives, starch, starch derivatives, xanthan, derivatized xanthan and mixtures thereof;
- and
- (ii) the crosslinking agent contains a metal selected from the group consisting of aluminum, antimony, zirconium and titanium.
A method of hydraulically fracturing a subterranean formation comprising:
- (a) pumping into the formation at least two stages wherein a first stage is a proppant-free fluid and a second stage is a proppant laden slurry and further wherein one of the stages contains a zirconium containing crosslinking agent and a first viscosifying polymer selected from the group consisting of carboxymethyl hydroxyethyl cellulose and carboxymethyl cellulose and the other stage contains a polyacrylamide friction reduction agent and at least one breaker selected from the group consisting of cellulases and oxidative breakers;
- and
- (b) degrading the first viscosifying polymer with the breaker, wherein the breaker has greater affinity for the first viscosifying polymer than the polyacrylamide friction reduction agent.
Dependencies are inferred from the claim text.