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Reducing Åsgard discharges

September 2, 1998, 01:00 CEST

The volume of drilling chemicals discharged on Norway's Åsgard field is being cut by returning drill cuttings to the reservoir.

Implemented on the Norwegian Sea field by joint operators Statoil and Saga Petroleum, this solution reflects advances in injection technology.

It marks the first use of such methods on a drilling rig - Transocean Winner. Cuttings have previously been injected only from fixed platforms, as on Statoil's Gullfaks field in the North Sea.

The injection programme is helping to fulfil the goals set by Norway's Miljøsok programme, says Grant Gundersen, health, environment and safety manager for Åsgard.

This industry-government collaboration aims to ensure that the Norwegian offshore sector is an environmental leader in global terms.
The new method has been tested for a year. Mr Gundersen says that the biggest challenge has been to identify geological strata, such as sandstones, which are easily penetrated by cuttings.

Instead of storing this materials as hazardous waste, some 2 000 tonnes of the cuttings per well is ground up on the rig and returned through the same well.
This solution adds to equipment and operational costs, says senior drilling manager Anton Tronstad on Transocean Winner. But it pays off by eliminating the expense of taking cuttings ashore and treating them there.

Transocean Winner is one of four rigs involved in drilling and completing production wells on Åsgard. Twenty of 59 planned producers have been finished so far, and the work will run to 2003.