Biodegradable surfactant for invert emulsion drilling fluid

A method of formulating an invert emulsion drilling fluid, said method comprising:

• mixing an oleaginous fluid, a non-oleaginous fluid, a biodegradable surfactant and a weighting agent, wherein the biodegradable surfactant includes a fatty acid ester of diglycerol or triglycerol in amounts sufficient to form an invert emulsion in which the oleaginous fluid is the continuous phase and the non-oleaginous fluid is the discontinuous phase.

A method of drilling a subterranean hole with an invert emulsion drilling fluid, said method comprising:

• mixing an oleaginous fluid, a non-oleaginous fluid, a biodegradable surfactant, and a weighting agent to form an invert emulsion, wherein the biodegradable surfactant includes a fatty acid ester of diglycerol or triglycerol in amounts sufficient to form an invert emulsion in which the oleaginous fluid is the continuous phase and the non-oleaginous fluid is the discontinuous phase, and
• drilling said subterranean hole using said invert emulsion as the drilling fluid.

A method of drilling a subterranean well with an invert emulsion drilling fluid, said method comprising:

• mixing an oleaginous fluid, a non-oleaginous fluid, a biodegradable surfactant, and a weighting agent to form an invert emulsion, wherein the biodegradable surfactant includes a fatty acid ester of diglycerol, wherein the fatty acid has the formula RCO2H in which R is an alkyl or akenyl having 10 to 20 carbon atoms and wherein the biodegradable surfactant is in amounts sufficient to form an invert emulsion in which the oleaginous fluid is the continuous phase and the non-oleaginous fluid is the discontinuous phase,
• circulating said invert emulsion within said subterranean well and
• drilling said subterranean well using said invert emulsion as the drilling fluid.

A method of drilling a subterranean well with an invert emulsion drilling fluid, said method comprising:

• mixing an oleaginous fluid, a non-oleaginous fluid, a biodegradable surfactant, and a weighting agent to form an invert emulsion, wherein the biodegradable surfactant includes a fatty acid ester of triglycerol, wherein the fatty acid has the formula RCO2H in which R is an alkyl or akenyl having 10 to 20 carbon atoms and wherein the biodegradable surfactant is in amounts sufficient to form an invert emulsion in which the oleaginous fluid is the continuous phase and the non-oleaginous fluid is the discontinuous phase,
• circulating said invert emulsion within said subterranean well and
• drilling said subterranean well using said invert emulsion as the drilling fluid.