INVERT EMULSION DRILLING FLUIDS AND METHODS OF DRILLING BOREHOLES

摘要

An invert emulsion drilling fluid, and a method for the use thereof in drilling wellbores, with good rheological properties at high temperatures and pressures. One embodiment of the drilling fluids are free of organophilic clays and lignites, free of calcium chloride, and comprise an alcohol in the internal phase, a quaternary ammonium emulsifier, and argillaceous solids. In one embodiment, the alcohol is a glycerol, a polyglycerol, or a mixture thereof. In one embodiment, the base oil for the emulsion is a paraffin and/or mineral oil. The drilling fluids provide good lubricity and high rates of penetration.