In one embodiment, a retarded acid system comprises an aqueous acid and a retarding surfactant. The aqueous acid may comprise from 5 wt. % to 25 wt. % of a strong acid, that is, an acid having a K.sub.a greater than or equal to 0.01. The aqueous acid may further comprise from 75 wt. % to 95 wt. % water. The retarding surfactant may have the general chemical formula R(OC.sub.2H.sub.4).sub.XOH where R is a hydrocarbon having from 11 to 15 carbon atoms and x is an integer from 6 to 10. The retarding surfactant may have a hydrophilic-lipophilic balance from 8 to 16.

The methods described herein, referred to as particle-templated emulsification (PTE), provide an improved approach for generating a monodisperse emulsion that encapsulates target particles of interest without requiring the use of a microfluidic device. Monodisperse droplets may be effectively obtained by using monodisperse particles to template the formation of droplets, which can include, e.g., monodisperse single-emulsion droplets, multiple-emulsion droplets, or Giant Unilamellar Vesicles (GUV), without destroying the integrity of the droplets.

Embodiments are directed to a lubricant package for water based drilling fluids. The lubricant package includes water, a polyethylene glycol, and a lubricating agent. The lubricating agent includes triethanolamine, or a C.sub.12-C.sub.14 alcohol ethoxylate, or a combination of triethanolamine and C.sub.12-C.sub.14 alcohol ethoxylate. The weight ratio of the polyethylene glycol to the lubricating agent in the lubricant package is from 1:2 to 2:1. Embodiments are also directed to a water-based drilling fluid composition including an aqueous base fluid, one or more additives, and the lubricant package for water based drilling fluids.

In one embodiment, a retarded acid system comprises an aqueous acid and a retarding surfactant. The aqueous acid may comprise from 5 wt. % to 25 wt. % of a strong acid, that is, an acid having a K.sub.a greater than or equal to 0.01. The aqueous acid may further comprise from 75 wt. % to 95 wt. % water. The retarding surfactant may have the general chemical formula R(OC.sub.2H.sub.4).sub.XOH where R is a hydrocarbon having from 11 to 15 carbon atoms and x is an integer from 6 to 10. The retarding surfactant may have a hydrophilic-lipophilic balance from 8 to 16.

An alkylene oxide derivative represented by following formula (I):

RO-(AO).sub.a[(PO).sub.b/(EO).sub.c]H(I)

(R represents a linear or branched alkyl group having from 4 to 36 carbons; AO is an oxyalkylene group having three or four carbons, PO is an oxypropylene group, and EO is an oxyethylene group; a, b, and c are the average addition molar numbers of the oxyalkylene group, the oxypropylene group, and the oxyethylene group per molecule, respectively, and 1a40, 1b40, 1c80, and (a+b+c)20; [(PO).sub.b/(EO).sub.c] represents a polyoxyalkylene group in which b moles of PO and c moles of EO are bonded randomly, and the random rate x is 0.1x1).

A drilling fluid composition which includes a base fluid, one or more additives, and a viscosifier package. The base fluid is an invert emulsion comprising oil and water. Further, the one or more additives is chosen from an emulsifier, a weighting material, a fluid-loss control additive, or an alkaline compound. The viscosifier package includes a fatty acid having 6 or more carbon atoms and an aliphatic polyester. The drilling fluid composition has a yield point of from 30 lb.sub.f/100 ft.sup.2 to 100 lb.sub.f/100 ft.sup.2 and a low shear yield point of from 10 lb.sub.f/100 ft.sup.2 to 40 lb.sub.f/100 ft.sup.2. The associated method of drilling a subterranean well including operating a drill in a wellbore in the presence of the drilling fluid composition is also provided.

In one embodiment, a spacer fluid may comprise a base fluid and a surfactant package. The surfactant package may comprise one or more surfactants, where the surfactant package comprises a first surfactant having the chemical structure R(OC.sub.2H.sub.4).sub.xOH. R may be a hydrocarbyl group having from 9 to 20 carbon atom, and x may be an integer from 5 and 15. The first surfactant may have a hydrophilic-lipophilic balance (HLB) of from 12 to 13.5.

Embodiments are directed to a lubricant package for water based drilling fluids. The lubricant package includes water, a polyethylene glycol, and a lubricating agent. The lubricating agent includes triethanolamine, or a C.sub.12-C.sub.14 alcohol ethoxylate, or a combination of triethanolamine and C.sub.12-C.sub.14 alcohol ethoxylate. The weight ratio of the polyethylene glycol to the lubricating agent in the lubricant package is from 1:2 to 2:1. Embodiments are also directed to a water-based drilling fluid composition including an aqueous base fluid, one or more additives, and the lubricant package for water based drilling fluids.

Provided is a heat-ray shielding particle dispersion which contains: ITO particles having a heat-ray shielding capability; a solvent containing 60% by mass or more of water; and a dispersant. The ITO particles have a BET specific surface area of 20 m.sup.2/g or more, have a blue or dark blue tone represented by an L value of 50 or less and a<0 and b<0 in the Lab color system, and are contained in an amount of 1-90% by mass with respect to 100% by mass of the dispersion. The solvent is a component obtained by removing the heating residue from the heat-ray shielding particle dispersion, and is contained in an amount of 6.1-99.0% by mass with respect to 100% by mass of the dispersion. The dispersant is at least one kind among a phosphate ester-based dispersant, a polyglycerin-based dispersant, a polyvinylpyrrolidone-based dispersant, a polyoxyethylene-polyoxypropylene condensate-based dispersant, and a polyacrylate-based dispersant.

Drilling fluid compositions include a base fluid, at least one additive chosen from an emulsifier, weighting material, fluid-loss additive, viscosifier, or alkali compound, and from 0.1 wt. % to 1 wt. %, based on total weight of the drilling fluid composition, of an ethoxylated alcohol compound having the formula R(OCH.sub.2CH.sub.2).sub.7OH, in which R is a saturated or unsaturated, linear or branched hydrocarbyl group having from 8 to 20 carbon atoms. The base fluid may be an aqueous base fluid. Methods for drilling a subterranean well include operating a drill in a wellbore in the presence of a drilling fluid composition including the base fluid, the additive, and the ethoxylated alcohol compound.