The North Sea operation of a global independent energy company has just completed a contract and was the first to use what is believed to be the world’s largest oilfield drilling bit.

Varel Oil and Gas Dill Bits was commissioned by Hess Corporation to design and build a 45-inch L111 (1,143mm) diameter drill-bit and the 5,100 pounds heavyweight was manufactured in Mexico before being shipped to Aberdeen for use in the Danish North Sea.

The milled-tooth roller cone bit was built to drill top hole sections big enough to run two subsequent 16-inch sections in a splitter well configuration by installing 40-inch conductor through 46-inch guides.

The hybrid bit – which incorporates an interchangeable polycrystalline diamond compact (PDC) bit in the centre – avoids the need for the pilot hole/rat hole traditionally associated with a hole opener assembly, as well as offering easier handling and reduced risk of failure.

It is being used over a series of splitter top holes in two drilling platforms located in the North Sea.

The new piece of equipment was based on Varel’s 44-inch L111 bit which has been successfully tried and tested in Saudi Arabia, the Far East and Africa.

Varel district manager North Sea Jason Marchant, said: “We are keen to push the limits on what bit sizes are available to give operators the best possible solution to new ways of drilling in this challenging market.

“We hope that the successful completion of this ground-breaking project, where good verticality was achieved, will lead to further work in the future.”

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