Worming away drilling waste

November 29, 2002, 09:15 CET

New approaches – including earthworm composting and asphalt production – are being pursued by Statoil in its search for good ways to treat drilling waste.

The group can already reuse some 67 per cent of oil-based drilling fluids and 50 per cent of water-based fluids.

Its total fluid management (TFM) project aims to help enhance value creation, in part by developing effective techniques for removing and reusing drill cuttings and drilling fluids.

“We must expect discharge curbs to become ever stricter in coming years,” says project manager John Eirik Paulsen.

“The TFM team is working to develop good environmental strategies and methods for reducing the problems posed by various types of waste from drilling and downhole operations.”

Recycling these materials so that none needs to be deposited as hazardous waste is the most attractive option. The TFM project has already managed to reduce their volume considerably.

Trials are currently under way at Norway’s Jordforsk research institute with earthworm composting of oily drill cuttings.

The worms are fed on cuttings and liquid mixed with animal waste, and convert the blend to a good fertilising compost.

In addition, Statoil has joined forces with Norwegian road surfacing specialist Veidekke to carry out trials on using oily cuttings for asphalt production.

“We find this interesting,” says Mr Paulsen. “Tests have not encountered gasification or other environmental problems, the asphalt is hardwearing and we have no residual waste.”

Drilling waste brought ashore accounts for roughly 60 per cent of the total cost of treating waste on land, including materials from Statoil’s land-based plants.