Patent ID: 7638466
Filing Date: 2009-12-29
Classification: C09K

Abstract:
1. A method of drilling a borehole in a subterranean formation at a temperature in the range of about 40° F. to about 250° F., comprising: providing or using in the drilling an invert emulsion drilling fluid comprising a continuous oil phase and having a plastic viscosity in the range of about 10 cP to about 60 cP and a yield point in the range of about 5 lb/100 ft adding to the drilling fluid before or during the drilling at least one non-ionic surfactant thinner, wherein the surfactant is the reaction product of at least one oxide, selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide, with C where R and where R such that the drilling fluid maintains during the drilling a plastic viscosity in the range of about 10 cP to about 60 cP and a yield point in the range of about 5 lb/100 ft