Some embodiments described herein provide a method comprising method comprising providing an oil-in-water emulsified spacer fluid comprising a binary surfactant mixture, solvent non-aqueous base fluid, and an aqueous base fluid, wherein the binary surfactant mixture comprises a surfactant and an amphiphilic co-surfactant, wherein the surfactant is present in an amount in the range of from about 0.5% to about 30% by weight of the oil-in-water emulsified spacer fluid and wherein the amphiphilic co-surfactant is present in an amount in the range of from about 0.5% to about 30% by weight of the oil-in-water emulsified spacer fluid, and introducing the oil-in-water emulsified spacer fluid into a subterranean formation comprising a residual non-aqueous fluid therein, wherein the binary surfactant mixture in the oil-in-water emulsified spacer fluid emulsifies at least a portion of the residual non-aqueous fluid.

Methods, fluids, compositions, and suspensions are provided for treating subterranean formations. The fluids can be servicing fluids, such as drilling or fracturing fluids. The fluids may include an aqueous base fluid and a polysaccharide. The aqueous base fluid may be admixed with a crosslinker suspension. The crosslinker suspension may include an emulsion, an emulsifier, and a boron containing compound.

Methods, fluids, compositions, and suspensions are provided for treating subterranean formations. The fluids can be servicing fluids, such as drilling or fracturing fluids. The fluids may include an aqueous base fluid and a polysaccharide. The aqueous base fluid may be admixed with a crosslinker suspension. The crosslinker suspension may include an emulsion, an emulsifier, and a boron containing compound.

A direct emulsion fluid includes an aqueous continuous phase, an oleaginous discontinuous phase, calcium carbonate comprising an organophillic coating, and a surfactant. A method may include emplacing into a formation a direct emulsion fluid and pumping a breaker fluid, wherein the breaker fluid degrades a filtercake formed by the direct emulsion fluid. The direct emulsion fluid may include an aqueous continuous phase; an oleaginous discontinuous phase; calcium carbonate comprising an organophillic coating; and a first surfactant.

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.

A method comprising drilling through a plurality of differing zones of a subterranean formation using a drilling fluid comprising a non-oleaginous continuous phase, an oleaginous discontinuous phase and at least a first salt dissolved into the non-oleaginous continuous phase. The amount of the at least first salt dissolved into the non-oleaginous continuous phase is maintained such that a density of the drilling fluid varies by no more than 10% while drilling through the plurality of zones.

Some embodiments described herein provide a method comprising method comprising providing an oil-in-water emulsified spacer fluid comprising a binary surfactant mixture, solvent non-aqueous base fluid, and an aqueous base fluid, wherein the binary surfactant mixture comprises a surfactant and an amphiphilic co-surfactant, wherein the surfactant is present in an amount in the range of from about 0.5% to about 30% by weight of the oil-in-water emulsified spacer fluid and wherein the amphiphilic co-surfactant is present in an amount in the range of from about 0.5% to about 30% by weight of the oil-in-water emulsified spacer fluid, and introducing the oil-in-water emulsified spacer fluid into a subterranean formation comprising a residual non-aqueous fluid therein, wherein the binary surfactant mixture in the oil-in-water emulsified spacer fluid emulsifies at least a portion of the residual non-aqueous fluid.

Some embodiments described herein provide a method comprising method comprising providing an oil-in-water emulsified spacer fluid comprising a binary surfactant mixture, solvent non-aqueous base fluid, and an aqueous base fluid, wherein the binary surfactant mixture comprises a surfactant and an amphiphilic co-surfactant, wherein the surfactant is present in an amount in the range of from about 0.5% to about 30% by weight of the oil-in-water emulsified spacer fluid and wherein the amphiphilic co-surfactant is present in an amount in the range of from about 0.5% to about 30% by weight of the oil-in-water emulsified spacer fluid, and introducing the oil-in-water emulsified spacer fluid into a subterranean formation comprising a residual non-aqueous fluid therein, wherein the binary surfactant mixture in the oil-in-water emulsified spacer fluid emulsifies at least a portion of the residual non-aqueous fluid.

Methods of delivering a low density solvent into a wellbore include combining an oleaginous solvent and a nonoleaginous fluid to form an emulsion, and injecting the emulsion into a wellbore. Other uses of low density solvent systems may include dissolving waxes and wax-containing residues in a wellbore, on downhole tools, from sand screens, or use in general cleanup operations in and outside of the wellbore.