Non-polluting non-toxic drilling fluid compositions and method of preparation

Claim 1

The process for the preparation of a non-polluting non-toxic plant or vegetable oil base drilling fluid composition comprising the steps of: (a) introducing a plant or vegetable base oil having a C-12 to C-24 carbon chain into a mixing container, (b) adding a minor amount of antioxidant to said base oil, (c) adding a minor amount of a synergist for said antioxidant, said synergist being selected from the group consisting of citric acid, ascorbic acid, phosphoric acid, monoesters of ascorbic acid and monoesters of fatty acids, to said base oil, (d) heating the said base oil including said antioxidants to a temperature of about 93° C. (200° F.), (e) introducing a minor amount of an oleate ester emulsifier into said base oil with thorough mixing, (f) adding a minor amount of viscosifier consisting of amine-treated bentonite into said mixture with thorough mixing, (g) introducing a minor amount of an oleate ester wetting agent into said mixture with thorough mixing, (h) shear mixing of the mixture for a period of not less than about 30 minutes to effect more thorough mixing to form a stable emulsion, and optionally (i) adding a finely-divided filler material into said mixture with thorough mixing to form a stable oil base drilling fluid composition having a low coefficient of friction less than about 0.15 for varied drilling purposes.