Drilling fluids: State of the art

This is a review article on the state-of-the-art in drilling fluid technology, including the recent advances in fluids for extended-reach and horizontal drilling. After a general review of mud technology, the currently used polymer additives are described, followed by a discussion of the new oil-based mud replacements, including the synthetic-based fluids and water-based muds formulated to have some oil-based mud characteristics.