Provided herein are compounds, compositions, and methods having application in the field of enhanced oil recovery (EOR). In particular, the compounds, compositions, and methods provided can be used for the recovery of a large range of crude oil compositions from challenging reservoirs.

Flowback aid mixtures and oil-in-water microemulsions produced by combining an aqueous brine with the flowback aid mixtures are disclosed. The flowback aid mixture comprises an oil, a fatty alcohol ethoxylate, and a quaternized fatty amine ethoxylate. The amount of oil is less than or equal to 12 wt. % based on the amount of flowback aid mixture. The microemulsions have a surface tension at 25° C. less than 30 mN/m and a Z-average particle size as determined by dynamic light scattering at 25° C. of less than or equal to 10 nm. Also disclosed are processes that utilize the flowback aid mixtures. In one process, the mixture is introduced into a subterranean formation and is combined prior to or during its introduction into the formation with a formation brine, process water, or both to give the microemulsion. In one hydraulic fracturing process for recovering gas, oil, or both, a fracturing fluid and the flowback aid are co-injected into a subterranean formation to give the microemulsion.

A water-based drilling mud composition may include an aqueous carrier, an asphalt sulfonate salt, and insoluble latex particles. The insoluble latex particles promote stabilization of an emulsion formed in response to introduction of an oil phase in the composition. The composition may include the emulsion including an oil phase dispersed as droplets in the aqueous carrier. The dispersed insoluble latex particles may be present in an oil-water interface between the oil phase and an aqueous phase of the aqueous carrier.

Methods and compositions comprising an emulsion or a microemulsion for use in various aspects of the life cycle of an oil and/or gas well are provided. In some embodiments, the emulsion or the microemulsion comprises water, a solvent, and a surfactant, and optionally, one or more additives.

Methods and compositions comprising an emulsion or a microemulsion for use in various aspects of the life cycle of an oil and/or gas well are provided. In some embodiments, the emulsion or the microemulsion comprises water, a solvent, and a surfactant, and optionally, one or more additives.

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

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

A method for drilling a borehole includes, while drilling, circulating a fluid composition. The fluid composition includes an aqueous continuous phase comprising an additive composition, the additive composition comprising an amphoteric polymer, a polyacrylamide, or a combination thereof; and an organic internal phase comprising a glycerol, a polyglycerol, a poly hydroxyl alcohol, a monosaccharide derivative, a polysaccharide derivative, or a combination thereof. In one embodiment, the additive composition includes a salt up to saturation and at least one of an amphoteric polymer or a polyacrylamide. In another embodiment, the additive composition includes a hydratable polymer, and an amphoteric polymer.

A method for drilling a borehole includes, while drilling, circulating a fluid composition. The fluid composition includes an aqueous continuous phase comprising an additive composition, the additive composition comprising an amphoteric polymer, a polyacrylamide, or a combination thereof; and an organic internal phase comprising a glycerol, a polyglycerol, a poly hydroxyl alcohol, a monosaccharide derivative, a polysaccharide derivative, or a combination thereof. In one embodiment, the additive composition includes a salt up to saturation and at least one of an amphoteric polymer or a polyacrylamide. In another embodiment, the additive composition includes a hydratable polymer, and an amphoteric polymer.

An effective amount of amphiphilic star polymers and surfactants may be applied to downhole fluids containing oil-in-water and water-in-oil emulsions, such as drilling fluids, completion fluids, drill-in fluids, workover fluids, and remediation fluids, to stabilize the emulsions and improve rheological properties of these fluids for use in oil and gas production operations. The star polymers and surfactants may be applied to the downhole fluid separately or as a blend to generate emulsions within the fluid that have substantially uniform droplet size.