Patent ID: 7635667

Claim:
A water based drilling fluid, for the drilling of subterranean boreholes, comprising: a) water as a continuous phase; b) a rate of penetration enhancing component comprising a synthetic, non-toxic ester-based oil; c) a lubrication enhancing component comprising: (I) a chlorinated component of chlorinated normal paraffins having 9 to 20 carbon atoms, chlorinated esters of fatty acids, chlorinated waxes, chlorinated olefins or mixtures thereof; and (ii) a sulfurized component of sulfurized fatty acid, sulfurized esters of fatty acids, sulfurized polymerized fatty acids, sulfurized olefins, or mixtures thereof, said chlorinated and sulfurized components being combined in proportions to produce a composition containing about 15 to 30 weight percent chlorine and about 2 to 10 weight percent sulfur; and d) a clay inhibition component comprising a polypropylene glycol, wherein said drilling fluid comprises about 4% by volume of rate of penetration enhancing component, 2% and 6% by volume of lubrication enhancing component, and 2% and 6% by volume of clay inhibition component.