Methods of forming and maintaining conductive propped fractures in SAGD and geothermal well applications
A method of forming propped fractures in a subterranean formation penetrated by a wellbore is provided. The method includes injecting a fracturing fluid through a (e.g., geothermal, SAGD) wellbore into the subterranean formation, thus creating fractures in the subterranean formation, whereby the aggregates and dissolvable particulates are positioned in the created fractures. The fracturing fluid comprises a carrier fluid; aggregates; and dissolvable particulates (e.g., proppant, sand; that dissolves over time under downhole conditions, e.g., T≥230° C.). The method further includes allowing the aggregates to cure into hardened masses (e.g., for functioning as pillars); and dissolving the dissolvable particulates, whereby voids and/or (e.g., solids-free) channels are formed in the (e.g., highly conductive) propped fractures, wherein the voids and/or channels (e.g., surround the solid masses and) provide pathways (e.g., for fluid to flow) through the (e.g., highly conductive) propped fractures (e.g., from the wellbore to another wellbore).
1 . A method of forming propped fractures in a subterranean formation penetrated by a wellbore, comprising:
injecting a fracturing fluid through a wellbore into the subterranean formation, thus creating fractures in the subterranean formation,
wherein the fracturing fluid comprises:
a carrier fluid;
aggregates, wherein the aggregates comprise a combination of aggregates of fly ash composite and aggregates of geopolymer; and
dissolvable particulates,
whereby the aggregates and dissolvable particulates are positioned in the created fractures;
allowing the aggregates to cure into hardened masses; and
dissolving the dissolvable particulates, whereby voids and/or channels are formed in the propped fractures, wherein the voids and/or channels provide pathways through the propped fractures.
2 . The method of claim 1 , wherein the dissolvable particulates comprise sand.
3 . The method of claim 1 , wherein the aggregates of fly ash composite comprise fly ash, cement, and a binding agent; wherein the aggregates of geopolymer comprise a geopolymer composition and a binding agent; or both wherein the aggregates of fly ash composite comprise fly ash, cement, and a binding agent and wherein the aggregates of geopolymer comprise a geopolymer composition and a binding agent.
4 . The method of claim 2 , wherein the geopolymer composition comprises an aluminosilicate, a metal silicate, and an activator.
5 . The method of claim 3 , wherein the aggregates of fly ash composite comprise the fly ash, the cement, and the binding agent.
6 . The method of claim 5 , wherein the aggregates of geopolymer comprise the geopolymer composition and the binding agent.
7 . The method of claim 1 , wherein the carrier fluid comprises a slick water or a gel.
8 . The method of claim 1 , wherein the propped fractures are highly conductive propped fractures that maintain porosity at closing pressures of greater than or equal to about 4000 psi.
9 . The method of claim 1 further comprising:
injecting steam into the wellbore during a SAGD process or injecting steam or another heat exchange fluid into the wellbore during a geothermal process.
10 . The method of claim 1 , wherein a majority of the dissolvable particulates comprise sand, silica, or a combination thereof.