Method of increasing lubricity of wellbore fluids

A method for increasing lubricity of a wellbore fluid comprising:

• i) preparing a water in oil microemulsion that contains insoluble particles of metal hydroxides and/or metal oxides in the inner aqueous phase, the insoluble particles being synthesized from their salt precursors in the water droplets of the microemulsion;
• ii) adding to the wellbore fluid the water in oil microemulsion;
• iii) injecting the wellbore fluid into a subterranean formation and
• iv) performing drilling, completion or coiled tubing operations in the subterranean formation,
• wherein the wellbore fluid is a drilling fluid, completion fluid or coiled tubing fluid.