Organoclays used as colloidal and rheological additives in oil-based drilling fluids: An overview

The objective of this paper is to give an overview of the synthesis, properties of different organoclays, including organo-montmorillonite, organo-sepiolite and organo-palygorskite, and their use as rheological additives in oil-based drilling fluids. The researches performed until the present moment are described and summarized. A significant amount of work had been done in this area, including the rheological behavior at normal and high temperature, the structure changes of organoclays in oil-based system, thermal stability and the rheological mechanisms. The role of layered and fibrous organoclays in oil-based drilling fluids in the enhancement of the rheological properties and thermal stability is deeply reviewed.