A recently-completed exploration well on Statoil’s Dolly prospect in the North Sea was drilled more rapidly than usual with the aid of innovative technology.
The well path passes through a Brent formation prospect – parts of which lie more than 2,500 metres below sea level – in the form of a curve.
After initially descending vertically, it angles out, becomes gently horizontal and then ascends at an angle of 106 degrees.
This approach is not unusual for production wells, but the Dolly wildcat is one of the first exploration wells drilled by Statoil to use the method.
The group utilised a Powerdrive drilling machine developed by Anadrill Schlumberger for the operation.
Computer controlled, this unit can drill longer stretches at a time and thereby reduces the time required. It has previously been deployed by Statoil on some of its North Sea fields.
“Viewed purely in terms of drilling technology, it’s all the same whether you’re drilling a producer or a wildcat,” explains Bengt Beskow, exploration manager for the Tampen area in Exploration & Production Norway.
“When we’re looking for supplementary oil on the fringes of mature fields, in satellites or in new areas like the Dolly prospect, however, we must try to rationalise drilling operations.”
He notes that two other recent Statoil exploration wells, in the Ole and Dole structures west of Gullfaks satellite Rimfaks, utilised new methods.
The Dolly wildcat was drilled from Deepsea Trym, and a project team is now working to evaluate results from the well – which encountered hydrocarbons.