| abstract |
FIELD: drilling. n SUBSTANCE: water-based drilling fluid contains water and from 0.01 to 10 wt % of a lubricant containing at least one oligomer, containing a reaction product of at least one substituted hydrocarbyl carboxylic acid, or ester, or anhydride of said acid and at least one polyalkylene glycol, wherein the hydrocarbyl substituent on the hydrocarbyl substituted carboxylic acid comprises a linear or branched C 6 -C 36 alkane or alkene and lubricating additive further comprises at least one of: i) from 0.01 to 10 wt % of metal dithiophosphate and ii) from 0.01 to 10 wt % of sulphonated olefin. n EFFECT: technical result is increased lubricating capacity and reduced friction coefficient of drilling fluid. n 14 cl, 7 tbl, 3 ex |