Abstract: A method of reducing the viscosity of invert emulsions and oil-based drilling fluids and well service fluids comprising such emulsions over a broad temperature range is disclosed. The method comprises adding to said invert emulsions of the invention a non-ionic surfactant alone or in combination with a co-thinner having the formula: R??—(C2H4O)n(C3H6O)m(C4H8O)k—H where R?? is a saturated or unsaturated, linear or branched, alkyl radical having about 8 to about 24 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging from about 0 to about 10, and k is a number ranging from about 0 to about 10. The non-ionic surfactant is a reaction product of ethylene oxide, propylene oxide and/or butylene oxide with C10-22 carboxylic acids or C10-22 carboxylic acid derivatives containing at least in position 9/10 and/or 13/14 structural units of general formula (I) where R1 is a hydrogen atom or an OH group or a group OR2.

Abstract: A method of reducing the viscosity of oil-based drilling fluids and well service fluids at low temperatures and a thinner compound for use in such drilling fluids and well service fluids is disclosed. The method comprises adding to said drilling fluids or well service fluids a thinner having the formula: R—(C2H4O)n(C3H6O)m(C4H8O)k-H where R is a saturated or unsaturated, linear or branched alkyl radical having about 8 to about 24 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging form about 0 to about 10, and k is a number ranging from about 0 to about 10.

Abstract: Diesel oil-based invert emulsion drilling fluids having fragile gel properties and improved performance. Methods are also disclosed for drilling, running casing, cementing, and/or producing hydrocarbons in a subterranean formation.

Abstract: A method of reducing the viscosity of oil-based drilling fluids and well service fluids at low temperatures and a thinner compound for use in such drilling fluids and well service fluids is disclosed. The method comprises adding to said drilling fluids or well service fluids a thinner having the formula: R—(C2H4O)n(C3H6O)m(C4H8O)k-H where R is a saturated or unsaturated, linear or branched alkyl radical having about 8 to about 24 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging form about 0 to about 10, and k is a number ranging from about 0 to about 10.

Abstract: A method of reducing the viscosity of invert emulsions and oil-based drilling fluids and well service fluids comprising such emulsions over a broad temperature range is disclosed. The method comprises adding to said invert emulsions of the invention a non-ionic surfactant alone or in combination with a co-thinner having the formula: R″″—(C2H4O)n(C3H6O)m(C4H8O)k—H where R″″ is a saturated or unsaturated, linear or branched, alkyl radical having about 8 to about 24 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging from about 0 to about 10, and k is a number ranging from about 0 to about 10. The non-ionic surfactant is a reaction product of ethylene oxide, propylene oxide and/or butylene oxide with C10-22 carboxylic acids or (C10-22 carboxylic acid derivatives containing at least in position 9/10 and/or 13/14 structural units of general formula (I) where R1 is a hydrogen atom or an OH group or a group OR2.