A water-in-oil emulsion drilling fluid can be converted into an oil mud-cement slurry for use in oil well cementing procedures. Also, a universal fluid can be prepared using the water-in-oil emulsion drilling fluid by treating with an hydraulic material so that it will lay down a filter cake during drilling which can be triggered to set into a hard cement and bond to the formation after the above oil mud-cement slurry has been placed in the borehole at the conclusion of drilling.