Numerous additives are now available for designing water-based drilling fluids but in most cases the best conditions for their implementation on fields and their limits of use are poorly documented. This paper presents a comparative study of performances of additives provided by different manufacturers for high temperature well drilling. New environmentally safe drilling fluids usable at temperatures up to 160°C have been designed using the best additives and their performances have been characterized using an original flow loop recently developed by IFP.
This equipment enables the evolution of drilling fluid properties, including HP-HT rheology and static and dynamic filtration, to be characterized inside the loop during aging under actual bottomhole conditions of temperature (180°C), pressure (500 bar) and shear (10000 s-1).
The results indicate that the selected formulations performed satisfactorily during these tests and their field use is now planned. Moreover, these tests provide data allowing field operators to improve predictions and control of the behavior of commonly used additives under downhole conditions.