A method of drilling a wellbore includes pumping an oleaginous wellbore fluid into a wellbore, the oleaginous wellbore fluid including an oleaginous continuous phase; a non-oleaginous discontinuous phase; an emulsifier stabilizing the non-oleaginous discontinuous phase in the oleaginous continuous phase; an organophilic clay; a weighting agent; and a wetting agent having an HLB ranging from about 4 to 10.5 that it selected such that the oleaginous wellbore fluid has a 600 rpm dial value at 40° F. of less than about 300 and a 10 minute gel strength of less than about 40 lbf/100 ft.sup.2.

A method of drilling a wellbore includes pumping an oleaginous wellbore fluid into a wellbore, the oleaginous wellbore fluid including an oleaginous continuous phase; a non-oleaginous discontinuous phase; an emulsifier stabilizing the non-oleaginous discontinuous phase in the oleaginous continuous phase; an organophilic clay; a weighting agent; and a wetting agent having an HLB ranging from about 4 to 10.5 that it selected such that the oleaginous wellbore fluid has a 600 rpm dial value at 40° F. of less than about 300 and a 10 minute gel strength of less than about 40 lbf/100 ft.sup.2.

Treatment fluids and methods of using a treatment fluid for minimizing fluid loss in a wellbore are disclosed. A method may comprise providing a drill-in fluid. The drill-in fluid may comprise an aqueous liquid, a base oil, a polyol, an emulsifying surfactant, and a solid bridging agent. The method may further comprise circulating the drill-in fluid through a drill-string and past a drill bit. The method may further comprise drilling in a reservoir section of a subterranean formation to extend a wellbore in the reservoir section the drill-in fluid is circulated therein.

Treatment fluids and methods of using a treatment fluid for minimizing fluid loss in a wellbore are disclosed. A method may comprise providing a drill-in fluid. The drill-in fluid may comprise an aqueous liquid, a base oil, a polyol, an emulsifying surfactant, and a solid bridging agent. The method may further comprise circulating the drill-in fluid through a drill-string and past a drill bit. The method may further comprise drilling in a reservoir section of a subterranean formation to extend a wellbore in the reservoir section the drill-in fluid is circulated therein.

Invert emulsions may be used in downhole operations to delay the swelling of water-swellable polymers. For example, a treatment fluid may be introduced into a wellbore penetrating a subterranean formation, the treatment fluid comprising an emulsion with an continuous oil phase and a discontinuous aqueous phase, an emulsifier, and a water-swellable polymer suspended in the continuous oil phase, wherein the aqueous discontinuous phase has a pH of about 0 to about 11; the emulsion may be broken while the treatment fluid in a portion of the subterranean formation; and the water-swellable polymer may be swollen into a swollen polymer, thereby reducing fluid flow through the portion of the subterranean formation. In some instances, for carbonate subterranean formation, the aqueous discontinuous phase may have a pH of about 7 to about 11.

Invert emulsions may be used in downhole operations to delay the swelling of water-swellable polymers. For example, a treatment fluid may be introduced into a wellbore penetrating a subterranean formation, the treatment fluid comprising an emulsion with an continuous oil phase and a discontinuous aqueous phase, an emulsifier, and a water-swellable polymer suspended in the continuous oil phase, wherein the aqueous discontinuous phase has a pH of about 0 to about 11; the emulsion may be broken while the treatment fluid in a portion of the subterranean formation; and the water-swellable polymer may be swollen into a swollen polymer, thereby reducing fluid flow through the portion of the subterranean formation. In some instances, for carbonate subterranean formation, the aqueous discontinuous phase may have a pH of about 7 to about 11.

An additive composition includes a rheology modifier selected from alcohol ethoxylates, amine ethoxylates, or ethylene oxide/propylene oxide copolymers, wherein the rheology modifier has an HLB ranging from about 4 to 10; and a winterizing agent that is at least one aliphatic non-ionic surfactant that has a branched structure and/or includes at least one unsaturation, wherein the winterizing agent has an HLB value between about 8 and 10.5.

An additive composition includes a rheology modifier selected from alcohol ethoxylates, amine ethoxylates, or ethylene oxide/propylene oxide copolymers, wherein the rheology modifier has an HLB ranging from about 4 to 10; and a winterizing agent that is at least one aliphatic non-ionic surfactant that has a branched structure and/or includes at least one unsaturation, wherein the winterizing agent has an HLB value between about 8 and 10.5.

An additive composition for improving one or more cold temperature properties in oil-based fluids is provided. One additive composition may include a first additive component selected from at least one alcohol ethoxylate, at least one amine ethoxylate, at least one ethylene oxide/propylene oxide copolymer, or a combination thereof, wherein the first additive component has an HLB ranging from about 4 to about 10. The additive composition may also include a second additive component selected from at least one alcohol, propylene glycol, at least one alcohol ethoxylate, or a combination thereof, wherein the second additive component has a total number of carbons from about 2 to about 30 carbons and a degree of ethoxylation is from zero to about 10.

An additive composition for improving one or more cold temperature properties in oil-based fluids is provided. One additive composition may include a first additive component selected from at least one alcohol ethoxylate, at least one amine ethoxylate, at least one ethylene oxide/propylene oxide copolymer, or a combination thereof, wherein the first additive component has an HLB ranging from about 4 to about 10. The additive composition may also include a second additive component selected from at least one alcohol, propylene glycol, at least one alcohol ethoxylate, or a combination thereof, wherein the second additive component has a total number of carbons from about 2 to about 30 carbons and a degree of ethoxylation is from zero to about 10.