Abstract: Methods for stimulating a subterranean formation and maintaining the conductivity therein may comprise: stimulating a subterranean formation comprising a carbonate mineral by performing matrix acidizing, hydraulic fracturing, or acid-fracturing upon the subterranean formation to form a plurality of flow pathways; after forming the plurality of flow pathways, introducing an ammonium phosphate salt in an aqueous carrier fluid into the subterranean formation; and interacting the carbonate mineral with the ammonium phosphate salt to convert at least a portion of the carbonate mineral into a hydroxyapatite mineral. The subterranean formation, after interacting with the ammonium phosphate salt, has an increased conductivity relative to the subterranean formation, after stimulating but before interacting with the ammonium phosphate salt, under a closure stress of about 600 psi or greater.

Abstract: Carbonates, such as chalk and limestone, are rather soft minerals and may lose at least some mechanical integrity after undergoing stimulation. For instance, carbonate minerals may experience proppant embedment or asperity weakening after fracturing or matrix acidizing. Methods for hardening a carbonate mineral may comprise: introducing an aqueous carrier fluid comprising an ammonium phosphate salt into a subterranean formation comprising a carbonate mineral, and interacting the carbonate mineral with the ammonium phosphate salt to convert at least a portion of the carbonate mineral into a hydroxyapatite mineral. The subterranean formation may exhibit an increased hardness after forming the hydroxyapatite mineral. The ammonium phosphate salt may be diammonium hydrogen phosphate in some examples.

Abstract: Carbonates, such as chalk and limestone, are rather soft minerals and may lose at least some mechanical integrity after undergoing stimulation. For instance, carbonate minerals may experience proppant embedment or asperity weakening after fracturing or matrix acidizing. Methods for hardening a carbonate mineral may comprise: introducing an aqueous carrier fluid comprising an ammonium phosphate salt into a subterranean formation comprising a carbonate mineral, and interacting the carbonate mineral with the ammonium phosphate salt to convert at least a portion of the carbonate mineral into a hydroxyapatite mineral. The subterranean formation may exhibit an increased hardness after forming the hydroxyapatite mineral. The ammonium phosphate salt may be diammonium hydrogen phosphate in some examples.

Abstract: A method of treating a carbonate formation includes introducing a stimulation fluid into the carbonate formation at a pressure greater than a fracture pressure of the formation and creating openings in the carbonate formation via the stimulation fluid. Then, a fluoride salt solution, optionally including a proppant, may be introduced into the carbonate formation such that it at least partially penetrates into the openings. The fluoride salt may then be reacted with a carbonate surface in the carbonate formation to form fluorite on a surface of the formation thereby increasing a hardness of the carbonate formation.