The present disclosure provides a lubricating oil composition which is excellent in metal fatigue life, wear resistance and electrical insulating properties, even when the composition has a reduced viscosity. The lubricating oil composition according to the present disclosure comprises: (A) a lubricating base oil; (B) from 0.6 to 4.0% by weight, based on the total weight of the lubricating oil composition, of a polydiene having a number average molecular weight of from 500 to 3,000 and containing a functional group on at least one end thereof; and (C) at least one selected from a phosphorus-based anti-wear agent and a phosphorus-based extreme pressure agent, the at least one agent being contained in such an amount that the content of phosphorus is from 50 to 500 ppm by weight based on the total weight of the lubricating oil composition.

A lubricating oil composition for an internal combustion engine includes: (A) a lubricating base oil including at least one mineral oil-based base oil and having a kinematic viscosity at 100° C. of from 2.0 mm.sup.2/s or more and 4.3 mm.sup.2/s or less, and (B) a calcium borate-containing metallic detergent in an mount of 500 mass ppm or more and less than 1500 mass ppm in terms of calcium, based on a total amount of the composition. The composition has an evaporation loss by NOACK method (250° C., 1 h) of from 10 mass % or more and 40 mass % or less, and the composition has a viscosity index of from 140 or more and 350 or less. The lubricating oil composition is provided, wherein even in the case of using a highly evaporative base oil to make the viscosity low, the friction characteristic of the lubricating oil composition can be kept low.

Drilling fluid compositions include invert emulsion fluids having an oleaginous phase, an aqueous phase, and an emulsifier composition that includes an ethoxylated alcohol compound and a polyaminated fatty acid compound. The ethoxylated alcohol compound has the formula R.sup.1—(OCH.sub.2CH.sub.2).sub.n—OH, where R.sup.1 is a hydrocarbyl group having from 8 to 22 carbon atoms and n is from 1 to 8. The ethoxylated alcohol compound has a Hydrophilic-Lipophilic Balance (HLB) of less than or equal to 6. The polyaminated fatty acid compound has the formula R.sup.2—CO—NH—CH.sub.2—CH.sub.2—N(COR.sup.2)—CH.sub.2—CH.sub.2—NH—CO—R.sup.3, where R.sup.2 is a hydrocarbyl group having from 1 to 20 carbon atoms and R.sup.3 is a hydrocarbyl group having from 1 to 10 carbon atoms or an alkylene carboxylate group having formula —R.sup.4—COOH, where R.sup.4 is a saturated or unsaturated hydrocarbylene having from 1 to 10 carbon atoms. Methods of drilling wells include operating a drill in a wellbore in the presence of drilling fluid compositions.

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.X—OH 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.

A well bore cementing system may comprise a spacer fluid and a cement slurry. The spacer fluid may be positioned within a well bore, and the spacer fluid may comprise a first surfactant package comprising one or more surfactants. The cement slurry may be positioned within the well bore, and the cement slurry may comprise a second surfactant package comprising one or more surfactants.

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.7—OH, 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.

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.x—OH. R may be a hydrocarbyl group having from 9 to 20 carbon atoms, 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.

A wellbore servicing fluid comprises an aqueous base fluid, one or more alkali metal or alkali earth metal salts, at least one visocisifier, and a filtration control package. The filtration control package may comprise a carboxylic acid and an ethoxylated alcohol compound. Alternatively, the filtration control package may comprise a polyethylene glycol. The carboxylic acid may have from 8 to 20 carbon atoms. The ethoxylated alcohol compound may have a general formula R—(OCH.sub.2CH.sub.2).sub.X—OH, where R is a hydrocarbon having from 10 to 16 atoms and x is an integer from 6 to 9. The ethoxylated alcohol compound may have a hydrophilic-lipophilic balance of from 8.0 to 16.0. The polyethylene glycol may have a mass average molar mass (M.sub.w) of less than or equal to 1500 daltons.

Cement slurries, cured cements, and methods of making cured cement and methods of using cement slurries are provided. The cement slurry contains water, a cement precursor material, an alcohol surfactant having from 10 to 20 carbon atoms and a carboxylic acid comprising an aliphatic chain having from 16 to 18 carbons. In some embodiments, the alcohol surfactant may comprise the formula R—(OC.sub.2H.sub.4).sub.x—OH where R is a hydrocarbyl group having from 10 to 20 carbons and x is an integer from 1 to 10. The cured cement contains water, cement, an alcohol surfactant having from 10 to 20 carbon atoms and a carboxylic acid comprising an aliphatic chain having from 16 to 18 carbons. In some embodiments, the alcohol surfactant may comprise the formula R—(OC.sub.2H.sub.4).sub.x—OH where R is a hydrocarbyl group having from 10 to 20 carbons and x is an integer from 1 to 10.