Patent ID: 8563479

Claim:
A water-based drilling mud composition with improved properties relative to tolerance of high salt content, cement, lime, and temperatures, the composition comprising: a. volcanic ash; b. water; c. a viscosifier, the viscosifier being present in an amount that ranges from about 0.3 wt. % to about 0.8 wt. % of the composition; d. a pH buffer, the pH buffer maintains a pH of the composition that ranges from 9 to 10.5; and e. a bi-functional mud additive, the composition consisting of up to about 25 pounds per barrel of monovalent salt, divalent salt, or a combination thereof with negligible or no changes in rheology or filtration behavior of the composition wherein the volcanic ash is present in a range of about 5 wt. % to about 8 wt. % of the composition; the water is present in an amount greater than about 90 wt. %; and the bi-functional mud additive is present in a range of about 0.5% (w/w) to about 1% (w/w) of the composition.