A method for controlling loss circulation in a subterranean formation and a convertible drilling mud operable to convert into a solid gel lost circulation material. The method includes circulating in a wellbore a nanosilica drilling fluid having a pH in a range of from about 8 to about 11 and a gel pH of less than 8, where the nanosilica drilling fluid includes an aqueous-based drilling mud, an alkaline nanosilica dispersion, and at least one additive. The method also includes introducing into the nanosilica drilling fluid an amount of a chemical activator sufficient to produce a convertible drilling mud where the chemical activator is an acid and the pH of the convertible drilling mud is less than the gel pH. The method also includes allowing the convertible drilling mud to convert into a solid gel lost circulation material.

Drilling fluid compositions and methods for using drilling fluid compositions are provided with enhanced anti-bit balling properties that includes an aqueous base fluid, one or more drilling fluid additives, and an anti-bit balling additive where the anti-bit balling additive comprises a C.sub.15-C.sub.18 alkene or a mixture of two or more C.sub.15-C.sub.18 alkenes. Methods for using the drilling fluid compositions may further include mixing the mixing an aqueous base fluid with one or more drilling fluid additives and an anti-bit balling additive, wherein the anti-bit balling additive includes a C.sub.15-C.sub.18 alkene or a mixture of two or more C.sub.15-C.sub.18 alkenes, and introducing the drilling fluid to a subterranean formation.

Drilling fluid compositions and methods for using drilling fluid compositions are provided with enhanced anti-bit balling properties that includes an aqueous base fluid, one or more drilling fluid additives, and an anti-bit balling additive where the anti-bit balling additive comprises a C.sub.15-C.sub.18 alkene or a mixture of two or more C.sub.15-C.sub.18 alkenes. Methods for using the drilling fluid compositions may further include mixing the mixing an aqueous base fluid with one or more drilling fluid additives and an anti-bit balling additive, wherein the anti-bit balling additive includes a C.sub.15-C.sub.18 alkene or a mixture of two or more C.sub.15-C.sub.18 alkenes, and introducing the drilling fluid to a subterranean formation.

A preparation method of an ionic liquid shale inhibitor for drilling fluid comprises the following step: subjecting the imidazole-based ionic liquid to a polymerization reaction in water environment under an inert atmosphere, and the produced polymer is used as an ionic liquid shale inhibitor for drilling fluid. The ionic liquid shale inhibitor for drilling fluid has the advantages of desirable inhibition effect, good compatibility, strong high-temperature resistance, simple preparation method and low cost.

The invention relates to the technical field of oil and gas drilling, and discloses an amphiphilic block polymer ultralow-permeability agent and an intelligent temporary plugging type water-based drilling fluid. The ultralow-permeability agent contains a structural unit provided by styryl hydrophobic monomer, maleic anhydride and acrylamide; the drilling fluid contains two or more of water, sodium bentonite, Pac-Lv, the ultralow-permeability agent, calcium carbonate, one-way plugging agent, white asphalt and barite which are stored in a mixed manner or independently stored. When the amphiphilic block polymer provided by the invention is used as the ultralow-permeability agent of the intelligent temporary plugging type water-based drilling fluid, the self-adaptive characteristic is realized; according to the amphiphilic block polymer, temporary plugging layer gaps formed in pore and throats by plugging materials in drilling fluid can be fully filled under the condition that the sizes and the distribution of the pore and throats of reservoirs are not required to be clear, so that the permeability of temporary plugging layer is greatly reduced, ultralow-permeability is realized, and the amphiphilic block polymer is weak in tackifying effect, has gel-improving effect and can improve the rheological property of the drilling fluid.

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.

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.

One or more embodiments presently described are directed to lubricants and methods for making such lubricants. According to one embodiment, a lubricant suitable for use in a water-based drilling fluid may comprise one or more alkyl esters and a fatty acid blend comprising at least palmitic acid and stearic acid. The sum of the weight percent of the palmitic acid and stearic acid may be at least 50 wt. % of the fatty acid blend. The weight ratio of the one or more alkyl esters to the fatty acid blend may be from 1:1 to 3:1. The molar ratio of palmitic acid to stearic acid may be from 20:80 to 40:60.

One or more embodiments presently described are directed to lubricants and methods for making such lubricants. According to one embodiment, a lubricant suitable for use in a water-based drilling fluid may comprise one or more alkyl esters and a fatty acid blend comprising at least palmitic acid and stearic acid. The sum of the weight percent of the palmitic acid and stearic acid may be at least 50 wt. % of the fatty acid blend. The weight ratio of the one or more alkyl esters to the fatty acid blend may be from 1:1 to 3:1. The molar ratio of palmitic acid to stearic acid may be from 20:80 to 40:60.

A wellbore servicing fluid comprising (a) a cationic formation stabilizer having (i) a molecular weight in a range of from equal to or greater than 0.05 to equal to or less than 2.0 kiloDaltons (kDa), or (ii) cationic charge functional groups of greater than 2 to equal to or less than 5 cationic charges per molecule, or (iii) both (i) and (ii), (b) an anionic friction reducer, and (c) an aqueous fluid.