Re-using water-based drilling mud has yielded financial savings and environmental benefits on several Statoil fields.
The group has so far re-utilised roughly 6,600 cubic metres of this fluid on Gullfaks and Statfjord in the North Sea and on Heidrun and Norne in the Norwegian Sea.
Providing an alternative to discharging mud to the sea, this approach represents a total financial gain of NOK 4.5 million for Statoil to date.
The Norwegian authorities permit water-based drilling fluids to be discharged, but the group feels that they contain chemicals which should preferably be recovered.
Drilling mud is a resource which both can and should be used over and over again, says Ellen Johanne Munkvold, manager for the fluids and drillability sector in Statoil's drilling and well technology unit.
A compensation agreement has accordingly been concluded by Statoil with its two largest suppliers of drilling mud.
"We've so far achieved an average saving on mud costs of NOK 150-200,000 per well," reports Ms Munkvold. "Our suppliers have also secured a gain, and the environment has been protected from additional burdens."
She adds that the new routine reflects Statoil's ambitious goal of reducing emissions which cause lasting environmental damage to zero.
Other companies have shown interest in the solution, and the group is continuing its efforts to widen the scope of re-use.