Water-based drilling-fluid systems for deepwater Norway

An innovative water-based drilling fluid system was developed for a well to be drilled in 837 m of water off Norway. The prequalified fluid was required to inhibit hydrates under normal drilling conditions and possess excellent shale inhibition characteristics to support hole stability and avoid bit balling. Because the primary objective was to obtain a noncontaminated formation water sample, the system had to exhibit superb fluid-loss control.