A composition including a coated nanoparticle and an ion, wherein the coated nanoparticle includes a nanoparticle, a linker, and a stabilizing group; methods of making and using the composition; and systems including the composition. The linker includes an anchoring group, a spacer, and a terminal group. The anchoring group is covalently bound to the nanoparticle and at least one of the terminal groups is covalently bound to at least one stabilizing group. A composition including a crosslinked-coated nanoparticle and an ion, wherein the crosslinked-coated nanoparticle includes a nanoparticle and a coating that includes a linker, a crosslinker, and a stabilizing group; methods of making and using the composition; and systems including the composition.

A polymer gel may comprise a polymer gel base material and superparamagnetic nanoparticles. At least 25 wt. % of the superparamagnetic nanoparticles may have diameters in a first size range between a first diameter and a second diameter. At least 25 wt. % of the superparamagnetic nanoparticles may have diameters in a second size range between a third diameter and a fourth diameter. The Brownian relaxation time of the portion of the superparamagnetic nanoparticles in the first size range may be at least 5 times the Neel relaxation time of the portion of the superparamagnetic nanoparticles in the first size range. The Neel relaxation time of the portion of the superparamagnetic nanoparticles in the second size range may be at least 5 times the Brownian relaxation time of the portion of the superparamagnetic nanoparticles in the second size range. Methods for monitoring gel integrity in a wellbore are further included.

A polymer gel may comprise a polymer gel base material and superparamagnetic nanoparticles. At least 25 wt. % of the superparamagnetic nanoparticles may have diameters in a first size range between a first diameter and a second diameter. At least 25 wt. % of the superparamagnetic nanoparticles may have diameters in a second size range between a third diameter and a fourth diameter. The Brownian relaxation time of the portion of the superparamagnetic nanoparticles in the first size range may be at least 5 times the Neel relaxation time of the portion of the superparamagnetic nanoparticles in the first size range. The Neel relaxation time of the portion of the superparamagnetic nanoparticles in the second size range may be at least 5 times the Brownian relaxation time of the portion of the superparamagnetic nanoparticles in the second size range. Methods for monitoring gel integrity in a wellbore are further included.

A process of recovering oil from an oil-bearing formation which process comprises injecting a surfactant containing enhanced oil recovery formulation into the formation via an injection well and recovering oil and optionally gas via a recovery well which process comprises determining the apparent viscosity of the enhanced oil recovery formulation at various ratios of enhanced oil recovery formulation to oil wherein the highest apparent viscosity is at most 4 times the lowest apparent viscosity measured.

Methods for reducing the amount of water produced from a subterranean formation can include the use of a gellable treatment fluid that comprises a quaternary ammonium salt as a gel-time modifier. The gellable treatment fluids can comprise an aqueous base fluid, a base polymer comprising an acrylamide monomer unit, an organic crosslinking agent, and a gel-time modifier comprising a quaternary ammonium salt.

Methods for reducing the amount of water produced from a subterranean formation can include the use of a gellable treatment fluid that comprises a quaternary ammonium salt as a gel-time modifier. The gellable treatment fluids can comprise an aqueous base fluid, a base polymer comprising an acrylamide monomer unit, an organic crosslinking agent, and a gel-time modifier comprising a quaternary ammonium salt.

Invertible latices suitable for use in enhanced oil recovery are formed by adding a first inversion surfactant and a second inversion surfactant to a water-in-oil latex comprising about 15 wt % to 50 wt % of a water soluble polymer having a net ionic charge. The first inversion surfactant has a hydrophilic/lipophilic balance of about 15 to 35 and an ionic charge that is the opposite of the net ionic charge of the polymer. The second inversion surfactant has a hydrophilic/lipophilic balance of between about 8 and 20. The invertible latices are diluted in a single step to provide dilute latices having 10,000 ppm or less polymer solids.

Invertible latices suitable for use in enhanced oil recovery are formed by adding a first inversion surfactant and a second inversion surfactant to a water-in-oil latex comprising about 15 wt % to 50 wt % of a water soluble polymer having a net ionic charge. The first inversion surfactant has a hydrophilic/lipophilic balance of about 15 to 35 and an ionic charge that is the opposite of the net ionic charge of the polymer. The second inversion surfactant has a hydrophilic/lipophilic balance of between about 8 and 20. The invertible latices are diluted in a single step to provide dilute latices having 10,000 ppm or less polymer solids.

The present invention relates to methods for preparing an aqueous acrylamide solution having a low acrylic acid concentration. In addition, the present invention relates to methods for reducing the acrylic acid concentration of an aqueous acrylamide solution. The methods involve a bioconversion of acrylonitrile to acrylamide in the presence of a biocatalyst, wherein during the bioconversion the content of acrylonitrile is maintained at 0.3 w/w % or more referred to the total weight of the composition in the reactor. Also provided is an aqueous acrylamide solution which is obtained by the methods of the present invention. Furthermore, the present invention is related to an acrylamide homopolymer or copolymer obtained by polymerizing the acrylamide of the aqueous solution.

The present invention relates to methods for preparing an aqueous acrylamide solution having a low acrylic acid concentration. In addition, the present invention relates to methods for reducing the acrylic acid concentration of an aqueous acrylamide solution. The methods involve a bioconversion of acrylonitrile to acrylamide in the presence of a biocatalyst, wherein during the bioconversion the content of acrylonitrile is maintained at 0.3 w/w % or more referred to the total weight of the composition in the reactor. Also provided is an aqueous acrylamide solution which is obtained by the methods of the present invention. Furthermore, the present invention is related to an acrylamide homopolymer or copolymer obtained by polymerizing the acrylamide of the aqueous solution.