Abstract: A method of improving rheological properties of a divalent brine based downhole treatment fluid at an elevated temperature comprises adding to the divalent brine based downhole treatment fluid a rheological modifier, which comprises a carboxylic acid ester, or a phosphate ester blended with an ethoxylated glycol, or a combination comprising at least one of the foregoing in an amount effective to improve the rheological properties of the divalent brine based downhole treatment fluid at a temperature of greater than about 200° F. The divalent brine based downhole treatment fluid comprises calcium bromide, calcium chloride, zinc bromide, zinc chloride, or a combination comprising at least one of the foregoing.

Abstract: A method of improving rheological properties of a divalent brine based downhole treatment fluid at an elevated temperature comprises adding to the divalent brine based downhole treatment fluid a rheological modifier, which comprises a carboxylic acid ester, or a phosphate ester blended with an ethoxylated glycol, or a combination comprising at least one of the foregoing in an amount effective to improve the rheological properties of the divalent brine based downhole treatment fluid at a temperature of greater than about 200° F. The divalent brine based downhole treatment fluid comprises calcium bromide, calcium chloride, zinc bromide, zinc chloride, or a combination comprising at least one of the foregoing.

Abstract: A treatment fluid comprises: a base fluid; a viscoelastic surfactant gelling agent and hydrophobic nanoparticles comprising metallic nanoparticles that are surface modified with C6-30 aliphatic groups. The treatment fluid is a fracturing fluid, a completion fluid, a gravel pack fluid, a fluid loss pill, a lost circulation pill, a diverter fluid, a foamed fluid, a stimulation fluid and the like.

Abstract: A viscoelastic surfactant treatment fluid comprises an aqueous base fluid an inorganic salt, the inorganic salt being present in an amount of greater than about 5 wt. % based on the total weight of the treatment fluid; a viscoelastic surfactant gelling agent effective to gel the aqueous base fluid by forming a plurality of micelles; and a cationic polymer additive associated with the micelles via electrostatic interactions.

Abstract: A method of improving rheological properties of a divalent brine based downhole treatment fluid at an elevated temperature comprises adding to the divalent brine based downhole treatment fluid a rheological modifier, which comprises a carboxylic acid ester, or a phosphate ester blended with an ethoxylated glycol, or a combination comprising at least one of the foregoing in an amount effective to improve the rheological properties of the divalent brine based downhole treatment fluid at a temperature of greater than about 200° F. The divalent brine based downhole treatment fluid comprises calcium bromide, calcium chloride, zinc bromide, zinc chloride, or a combination comprising at least one of the foregoing.

Abstract: A method of improving rheological properties of a divalent brine based downhole treatment fluid at an elevated temperature comprises adding to the divalent brine based downhole treatment fluid a rheological modifier, which comprises a carboxylic acid ester, or a phosphate ester blended with an ethoxylated glycol, or a combination comprising at least one of the foregoing in an amount effective to improve the rheological properties of the divalent brine based downhole treatment fluid at a temperature of greater than about 200° F. The divalent brine based downhole treatment fluid comprises calcium bromide, calcium chloride, zinc bromide, zinc chloride, or a combination comprising at least one of the foregoing.

Abstract: Methods and formulations useful for controlling and optimizing the rheological properties of invert emulsion (water-in-oil) drilling fluids at low and high temperatures, wherein an additive is incorporated into an invert emulsion drilling fluid, the additive being made up of at least one organophilic clay, at least one weighting agent, at least one emulsifier, at least one filtration control agent, at least one polyamide resin, and at least one ethoxylated alcohol-based or an ether carboxylic acid-based rheology modifier.

Abstract: A viscoelastic surfactant treatment fluid comprises an aqueous base fluid an inorganic salt, the inorganic salt being present in an amount of greater than about 5 wt. % based on the total weight of the treatment fluid; a viscoelastic surfactant gelling agent effective to gel the aqueous base fluid by forming a plurality of micelles; and a cationic polymer additive associated with the micelles via electrostatic interactions.

Abstract: 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 C6-30 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.

Abstract: 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 C6-30 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.

Abstract: A method of treating a subterranean formation penetrated by a well comprises combining an aqueous base fluid, a viscoelastic surfactant gelling agent, two or more types of the following nanoparticles: an alkaline earth metal oxide; an alkaline earth metal hydroxide; a transition metal oxide; or a transition metal hydroxide to form a treatment fluid, and pumping the treatment fluid into the well, wherein the weight ratio of the two or more types of the nanoparticles is selected such that the treatment fluid has an improved fluid efficiency as compared to an otherwise identical reference fluid except for comprising only one type of the nanoparticles selected from an alkaline earth metal oxide; an alkaline earth metal hydroxide; a transition metal oxide; and a transition metal hydroxide.

Abstract: A method of improving rheological properties of a divalent brine based downhole treatment fluid at an elevated temperature comprises adding to the divalent brine based downhole treatment fluid a rheological modifier, which comprises a carboxylic acid ester, or a phosphate ester blended with an ethoxylated glycol, or a combination comprising at least one of the foregoing in an amount effective to improve the rheological properties of the divalent brine based downhole treatment fluid at a temperature of greater than about 200° F. The divalent brine based downhole treatment fluid comprises calcium bromide, calcium chloride, zinc bromide, zinc chloride, or a combination comprising at least one of the foregoing.

Abstract: 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 C6-30 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.

Abstract: A method of treating a subterranean formation penetrated by a well comprises combining an aqueous base fluid, a viscoelastic surfactant gelling agent, two or more types of the following nanoparticles: an alkaline earth metal oxide; an alkaline earth metal hydroxide; a transition metal oxide; or a transition metal hydroxide to form a treatment fluid, and pumping the treatment fluid into the well, wherein the weight ratio of the two or more types of the nanoparticles is selected such that the treatment fluid has an improved fluid efficiency as compared to an otherwise identical reference fluid except for comprising only one type of the nanoparticles selected from an alkaline earth metal oxide; an alkaline earth metal hydroxide; a transition metal oxide; and a transition metal hydroxide.

Abstract: The stability of subterranean, laminated, carbonate-containing formations that have strongly hydrophilic-wet surfaces is improved by introducing into the formation an aqueous fluid having dispersed therein relative permeability modifiers (RPMs). The RPMs are designed to enter the fractures and gaps between the layers in the formation and alter their surface wettability to inhibit water from further entering into the shale rock, thereby improving stability.