DRILLING MUD

摘要

The present invention relates to an invert emulsion drilling mud having a continuous oil phase substantially free of mineral oil; a disperse aqueous phase; emulsifier means; weighting agent means. In one aspect of the invention the oil phase consists essentially of a natural triglyceride ester oil which oil has a substantially reduced gum content. In another aspect the oil phase consists essentially of a natural triglyceride ester oil and a non-toxic biodegradable viscosity reducing diluent, said emulsion has a pH which is not strongly alkaline and is substantially lime-free, and said emulsifier means is effective under not strongly alkaline substantially lime-free conditions.