Abstract: Methods that include a method of determining one or more approximate properties of a subterranean formation and/or a fracture therein comprising: obtaining fluid identity data for a plurality of flowback fluid samples; and using a reservoir model, with the fluid identity data and one or more subterranean formation properties as inputs thereto, to estimate one or more properties in a subterranean formation. Additional methods are provided.

Abstract: Methods that include a method of determining one or more approximate properties of a subterranean formation and/or a fracture therein comprising: obtaining fluid identity data for a plurality of flowback fluid samples; and using a reservoir model, with the fluid identity data and one or more subterranean formation properties as inputs thereto, to estimate one or more properties in a subterranean formation. Additional methods are provided.

Abstract: Viscoelastic surfactant fluids, and methods of using such fluids and controlling the viscosity thereof. In one embodiment, the methods of the present invention comprise: providing a viscoelastic surfactant fluid that comprises an aqueous-base fluid, and a surfactant; providing a metal ion having at least two oxidation states wherein at least one of the oxidation states interferes with the ability of the surfactant to form a viscosifying micelle, wherein at least a portion of the metal ion is present in an oxidation state that interferes with the ability of the surfactant to form a viscosifying micelle; allowing the metal ion to interact with viscoelastic surfactant fluid so as to decrease the ability of the surfactant to form a viscosifying micelle; and introducing the viscoelastic surfactant fluid into at least a portion of a subterranean formation.

Abstract: Methods and compositions for reducing the precipitation of aluminum compounds following the contact of an aluminum containing subterranean formation with an acid solution containing hydrofluoric acid are provided. In accordance with the methods, a hydroxy carboxylic acid is combined with the hydrofluoric acid solution and the subterranean formation is contacted with the resulting acid solution.

Abstract: Methods and compositions for reducing the precipitation of fluoride compounds following the contact of an aluminum containing subterranean formation with an acid solution containing hydrofluoric acid are provided. In accordance with the methods, a hydroxy carboxylic acid is combined with the hydrofluoric acid solution and the subterranean formation is contacted with the resulting acid solution.

Abstract: Methods and compositions for reducing the precipitation of metal sulfides from acid solutions are provided. The methods basically comprise reducing the precipitation of metal sulfide compounds from an aqueous acid solution when the solution dissolves sulfide and metal ions by combining at least one oxime with the acid solution in an amount whereby the oxime preferentially reacts with sulfide ions in the solution and thereby prevents the sulfide ions from reacting with metal ions therein.