Disclosed herein are compositions and methods for increasing recovery, or flowback, of hydrocarbon compounds from hydrocarbon-containing subterranean fractured rock formations (tight shale reservoirs). The flowback compositions include an anionic dimer surfactant, an anionic monomer surfactant, and a demulsifier. The flowback compositions convert oil-wet rocks to water-wet, yet exhibit a low tendency of composition components to sorb to the rock. The flowback compositions do not cause formation of emulsions with hydrocarbon compounds within the subterranean fractured rock formations. The flowback composition are useful for increasing the yield of hydrocarbons recovered from tight shale reservoirs.

Emulsions, treatment fluids and methods for treating subterranean formations are provided, wherein the emulsions comprise water, a water-immiscible liquid, one or more polymers, and an inverting surfactant composition comprising one or more salts of alkyl ether sulfates, one or more ethoxylated amine compounds and one or more organic or inorganic salts. The emulsions are particularly suitable for use in harsh brine conditions.

A method of breaking the viscosity of a treatment fluid comprises: adding hydrophobic nanoparticles to a treatment fluid comprising a base fluid and a viscoelastic surfactant gelling agent, the hydrophobic nanoparticles comprising metallic nanoparticles that are surface modified with C.sub.6-30 aliphatic groups, wherein the hydrophobic nanoparticles are added in an amount effective to decrease the viscosity of the treatment fluid as compared to a treatment fluid absent the hydrophobic nanoparticles.

A fluid including: (i) a continuous aqueous phase, wherein the continuous aqueous phase has total dissolved solids in a concentration of at least 30,000 mg/l; (ii) an alkyl amido quaternary amine; (iii) a polymer, wherein the polymer is water-soluble or water-hydratable; and (iv) a crosslinker for the polymer. The continuous aqueous phase of the fluid can include a water source selected from the group consisting of flowback water, produced water, and any combination thereof. Methods include: (A) forming a fluid according to any of the various embodiments of the disclosure, and (B) introducing the fluid into a well. For example, the fluid can be used as a fracturing fluid for fracturing a treatment zone of a well.

The present invention relates to a method for producing mineral oil from underground mineral oil deposits, in which an aqueous formulation comprising at least a mixture of alkyl ether carboxylate and corresponding alkyl ether alcohol, where the alkyl ether carboxylate has been prepared from the alkyl ether alcohol and the molar ratio in the mixture of alkyl ether carboxylate:alkyl ether alcohol is from 51:49 to 92:8, is injected through at least one injection well into a mineral oil deposit, where the deposit has a deposit temperature of 55° C. to 150° C., a crude oil having more than 20° API and a deposit water having more than 100 ppm of divalent cations, and crude oil is withdrawn through at least one production well from the deposit. The invention further relates to the preparation of the mixture and to a concentrate comprising the mixture.

Methods including deactivation and activation of permeability modifiers for use in subterranean formation operations. A first treatment fluid may be introduced into a subterranean formation having a first treatment zone having a first aqueous permeability value, the first treatment fluid comprising a first aqueous base fluid and a deactivated permeability modifier. The deactivated permeability modifier may be adsorbed onto a surface of the first treatment zone. A second treatment may thereafter be introduced into the subterranean formation, the second treatment fluid comprising a second aqueous base fluid and a cyclodextrin compound. The second treatment fluid may contact the deactivated permeability modifier to activate the permeability modifier by complexing the deactivating surfactant with the cyclodextrin compound, thereby forming an activated permeability modifier adsorbed onto the surface of the first treatment zone and reducing the aqueous permeability of the first treatment zone.

Methods including deactivation and activation of permeability modifiers for use in subterranean formation operations. A first treatment fluid may be introduced into a subterranean formation having a first treatment zone having a first aqueous permeability value, the first treatment fluid comprising a first aqueous base fluid and a deactivated permeability modifier. The deactivated permeability modifier may be adsorbed onto a surface of the first treatment zone. A second treatment may thereafter be introduced into the subterranean formation, the second treatment fluid comprising a second aqueous base fluid and a cyclodextrin compound. The second treatment fluid may contact the deactivated permeability modifier to activate the permeability modifier by complexing the deactivating surfactant with the cyclodextrin compound, thereby forming an activated permeability modifier adsorbed onto the surface of the first treatment zone and reducing the aqueous permeability of the first treatment zone.

Certain particulates of encapsulated treatment chemicals, and methods of and systems for their use in subterranean formations, are provided. In one embodiment, the methods comprise: providing a plurality of treatment particulates, at least one of which comprising a polymer matrix that comprises and/or encages at least one treatment chemical and a coating disposed around an outer surface of the polymer matrix; and introducing the treatment particulates into a well bore penetrating at least a portion of a subterranean formation.

The invention relates to a novel sulfobetaine monomer and to a process for the preparation thereof, advantageously by reaction between a vinyl-amine compound and a vinyl-sulfonic acid compound, preferably in the presence of a solubilizing agent. The invention also relates to the (co)polymers obtained from this novel type of sulfobetaine monomer, and to the use thereof, for example as a flocculant, dispersing agent, thickening agent, absorbent agent or friction-reducing agent.

Disclosed are compositions and methods for the pressure protection of existing wells during infill drilling operations.