Influence of an ionic liquid on rheological and filtration properties of water-based drilling fluids at high temperatures

Ionic liquids have attracted significant research interest due to their unique thermal stability. In this paper, the influence of a water-soluble ionic liquid on the rheological and filtration properties of water-based drilling fluids at high temperature is investigated. The drilling fluids are evaluated by means of rheological and filtration tests following the American Petroleum Institute (API) standards, submitted to an aging process or at high temperature. The experimental results show that the rheological behavior of water-based drilling fluids is improved and enhanced in the presence of low concentration of ionic liquid (as low as 0.05 mass%) at high temperatures (even up to 240 °C). Meanwhile, the high-temperature and high-pressure (HTHP) filtration volumes are reduced by as much as 52% compared with that of polymer water-based drilling fluids without ionic liquid. The study of the mechanism demonstrates that the water-soluble ionic liquid have an excellent capacity to improve the rheological and filtration properties of water-based drilling fluids at high temperatures due to the high thermal stability and cation exchange ability of the ILA.