Masterbatch for the drilling fluid manufacture

An oil-based masterbatch in the form of granules containing carbon nanotubes. Also, a method for preparing an oil-based masterbatch in the form of granules containing carbon nanotubes. Also, the use of an oil-based masterbatch in the form of granules containing carbon nanotubes for manufacturing an aqueous or organic viscoelastic fluid, intended for drilling in underground formations.