Greener well completions

July 21, 1999, 10:00 CEST

A new method which avoids flaring of well fluids on mobile rigs has been adopted by two Statoil subsea developments in the North Sea.

Applied for testing and cleaning new production wells on the Statfjord and Gullfaks satellites, this solution helps to reduce polluting emissions.

It involves sending the wellstream directly to the processing facilities on Statfjord C and Gullfaks A respectively, rather than to the rig's flare boom.

That cuts the release of greenhouse gases, avoids the possible formation of dioxins and reduces the danger of oil spills.

Statoil has long sought to reduce such emissions, in part by chartering the special Crystal Sea oil collection vessel.

The new method will also make it possible to complete production wells faster than before, reducing rig use by about two days at a saving of roughly NOK 5 million per well with today's rates.

Because hydrocarbons are not taken aboard the rig, the solution also enhances safety and improves the working environment by cutting noise and heat.

A total of four production wells have so far been completed on the Statfjord satellites with the aid of the new system.

"Experience so far has been very positive," reports Kjell Lejon, a senior well and production engineer in the resource development department for the Statfjord satellites.

"We haven't observed process-related problems other than those normally encountered in bringing platform wells on stream."

The flaring-free method for downhole cleaning has also been applied to five wells on the Gullfaks satellites, reports staff engineer Terje S Kristiansen in the drilling and well technology department for these fields.

"Although this procedure has imposed some extra loads and costs for Gullfaks A, our overall experience is positive," he says.