Drilling more cheaply

September 4, 1998, 06:00 CEST

A new type of drilling machine adopted by Statoil can complete a well up to 40 per cent faster, saving large sums.

On Statfjord A, the AutoTrak rotary closed loop drilling system has made it possible to drill 1 809 metres of a horizontal well in one run.

This record accomplishment cut drilling time by at least three days and trimmed about NOK 2 million from rig costs. The machine also allows the well to be positioned in the most prolific zones.

It has been used successfully on Statoil's Veslefrikk field to drill a demanding well path over more than 3 100 metres. This work was completed 12 days earlier than expected.

Still drilling on Statfjord A, the automatically steerable AutoTrak solution has been developed and marketed by oil service company Baker Hughes Inteq.

The Statfjord A well marks the greatest length drilled by a rotating steerable system in the entire oil industry, reports Espen Andreassen.

"This equipment has proved to be past the teething stage," he says. "I believe it will become a standard solution for demanding wells with deviated paths."

Technical network manager for directional drilling and well positioning in Statoil, Mr Andreassen adds that the enhanced ability to steer the bit in any direction outperforms conventional motorised drilling.

This allows the well to be guided to the most favourable reservoir areas. In addition to advancing faster, the borehole is more efficiently cleaned of drill cuttings - reducing the risk of stuck pipe.

Rotating the drill string means that friction in the well no longer prevents effective progress and longer reach. The operator can thereby make wider use of water-based rather than oil-based muds, which yields an environmental gain.

Statoil is also trying out competing equipment, and was the first operator off Norway to utilise the automatically steerable rotary technology in 1997.