Patent ID: 7939470

Claim:
An invert emulsion drilling fluid for drilling in a subterranean formation comprising: an oleaginous continuous phase; an internal phase comprising an alcohol; a quaternary ammonium emulsifier, selected from the group consisting of quaternary ammonium compounds having a general formula: where R 1 , R 2 , R 3 is selected from the group consisting of: H; saturated or unsaturated alkyl groups containing C 1 to C 22 carbon atoms; aromatic groups; alkyl-aryl groups; heterocyclic groups; sugar groups; R 4 is an alkyl group containing C 8 to C 22 carbon atoms; X is selected from the group consisting of: anions, halogens, sulfate ions, nitrate ions, citrate ions, formate ions, phosphate ions, acetate ions, methylsulfonate ions, paratoluene sulfonates and chloride anions; or a general formula: where R 1 , R 2 , R 4 , R 5 is selected from the group consisting of: H; saturated or unsaturated alkyl groups containing C 1 to C 22 carbon atoms; aromatic groups; alkyl-aryl groups; heterocyclic groups; sugar groups; R 3 , R 6 are selected from the group consisting of alkyl groups containing C 8 to C 22 carbon atoms; Y is hydrophobic, partially hydrophobic, aromatic, cyclic or acyclic and selected from the group consisting of: O; O(CH 2 ) n or (CH 2 ) n , where n=1 to 18; ketonic groups, ester groups, amide groups; X is selected from the group consisting of: anions, halogens, sulfate ions, nitrate ions, citrate ions, formate ions, phosphate ions, acetate ions, methylsulfonate ions, paratoluene sulfonates and chloride anions; and argillaceous solids.