Recovery of hydrocarbons from a mixture of hydrocarbons and drilling fluid by selective reaction of the drilling fluid leaving the hydrocarbon unaffected

摘要

A method of separating from a mixture of oil-based drilling fluid and sample of formation hydrocarbon, the liquid component of the drilling fluid, which method comprises (a) treating, e.g. chemically or enzymatically the mixture in a way that selectively treats the liquid component of the drilling fluid, producing one or more treatment products, while leaving the formation hydrocarbon unaffected; and (b) separating the treatment product(s) from the formation hydrocarbon, e.g., by solvent extraction. The liquid component of the drilling fluid preferably comprises one or more esters (which do not occur in significant quantities in naturally occurring formation hydrocarbons) and which can be hydrolysed to give water-soluble products readily removable from the formation hydrocarbon. The invention may be applicable to the sampling of formation hydrocarbon using wireline formation testers or sampling tools allowing one to obtain an uncontaminated sample of formation hydrocarbon within a reasonable sampling time. Methods of treatment such as chemical oxidation or epoxidation or enzyme mediated oxidation or hydroylsis, or example, using pig liver esterase or porcine pancreatic lipase may be used to selectively treat the drilling fluid.