James W Mercer

US Patent:

50968831, Mar 17, 1992

Filed:

Aug 9, 1991

Appl. No.:

7/745998

Inventors:

James D. Mercer - Lake Elsinore CA
Laura L. Nesbit - Nikiski AK

Assignee:

Union Oil Company of California - Los Angeles CA

International Classification:

C09K 706
C09K 702

US Classification:

507103

Abstract:

A non-toxic drilling fluid (drilling mud), for use in rotary-type well-drilling operations, comprises a non-toxic base-oil consisting essentially of branched-chain paraffins which may or may not contain ester functionalities, the base-oil having: (i) between about 16 and about 40 atoms per molecule, (ii) a kinematic viscosity, at 40. degree. C. , of between about 1 and about 16. 5 centistokes; (iii) a flash point of at least about 90. degree. C. ; and (iv) a pour point of less than about -40. degree. C. Preferably, the branched-chain paraffin used as the base-oil consists essentially of the dimer of 1-decene, which has a viscosity of about 5 centistokes at 40. degree. C. and which has 20 carbon atoms per molecule. The drilling fluid can be about 100 percent base-oil or can be an emulsion of the base-oil in water, in which case the amount of base-oil is at least about 30 volume percent, and is more preferably between about 65 and about 95 volume percent. The drilling fluid additionally includes various additives, including emulsifiers, viscosifiers, weighting agents, oil-wetting agents, densifiers, and/or fluid-loss preventing agents.