Environmental Technology, News, Oil & Gas

Zero Tolerance for oily water

Using technological innovations developed in Norway, Norwegian oil and gas producers have committed themselves to an ambitious environmental goal: "zero discharge" of produced water in offshore field developments.

Oil producers and technology companies expect the effort to spawn a multitude of benefits. Healthy oceans, after all, affect all of life on earth. Politically, the goal reflects the oil industry’s strong commitment to sharing the sea with the fishing industry. The first beneficiary of the new zero-discharge push will be the marine life off Norway’s Lofoten archipelago and northward into the Barents Sea.

“The goal for future field developments in the northern seas is zero discharges to sea,” says Finn Roar Aamodt, director general of the Norwegian Oil Industry Association. “We want to adapt all future production to a conflict-free co-existence with thefishery industry. This is the goal, and I have good hope that we will succeed in reaching it.”

Reinjecting Produced Water

When the new fields achieve operational status, produced water will be routed back to the subsurface and reinjected into reservoirs, rather than released into the sea. While the plan is a major victory for the environment, it is not a complete solution to the problem. Small discharges of produced water will still occur in connection with start-up, shutdown and minor operating interruptions. Various technological solutions are being considered to end these smaller discharges.

The treatment of cuttings and drill fluid is another issue being tackled by Norwegian technology and engineering firms. When wells are drilled, those dirty by-products will be reinjected or brought to land. Water-based drilling fluid may be introduced. The industry is also developing ways to achieve more efficient return and collection of production and drilling chemicals.

Thanks to new technology, well testing will no longer lead to flow to the surface. The wellstream to be tested can be transferred to vessels by the rig and then collected. Or, testing can actually take place in the well, which makes testing over the flare boom unnecessary.

Happy Fishermen

All exploration and well activities in the Lofoten/Barents Sea area will be conducted with heightened sensitivity to environmental conditions, helping reduce harm to fish, sea birds and other marine life. Stringent technical and operational criteria regarding discharges will apply to all drilling installations and vessels.

As Norwegian installations in the future will primarily be based on the seabed, efforts to improve conditions for the fishery industry include trawl-friendly designs for all seabed installations and pipelines. The industry also aims to cooperate with fishery interests in connection with seismic surveys.

Troll Pilot: On the Floor

Norsk Hydro’s Troll Pilot development is a major step towards zero discharge. Operating at a depth of 340 m, Troll Pilot is a seabed facility that separates produced water from the wellstream and reinjects the water below the sea floor, permitting only products of value to rise to the platform for further processing. Norsk Hydro protects the environment, saves energy and cuts production costs.

The revolutionary subsea separation system was developed by Norsk Hydro in order to address the challenge of removing produced water from the thin oil layers of the Troll reservoir. Wellstreams can be as much as 80 per cent water. Hydro engineers saw that by moving the separation function from the platform to the seabed, it could produce and process more oil. Troll Pilot currently has a processing capacity of 8,000 m3 per day and capacity for water injection of 6,000 m3 per day.

As with many innovations originating in Norway, the Troll Pilot project was the result of collaboration, this time between Norsk Hydro and ABB. The two companies pooled resources to install the groundbreaking new equipment in May 2000, and the facility has been running regularly since the summer of 2001. By the end of that year, Troll Pilot had reinjected some 245,000 m3 of water.

But Norsk Hydro and ABB are not alone in the quest for cleaner, more efficient exploration and development operations. Statoil is another stickler for clean water. Its ambitious goal is to achieve zero harmful discharges into the sea in all operations by 2005. The enthusiasm behind such goals reflects a commendable corporate culture, but it also says a lot about the technology and skills of Norway’s offshore supply industry.

It’s Good Business, Too

According to the Norwegian Oil Industry Association, the goal of eliminating produced-water discharges is part of a larger understanding that cleaner development of petroleum resources may benefit more than just the natural world. It may also enrich the industry, through greater efficiency and competitiveness in production.

“We have set high goals for future activities,” says Aamodt. “New technology will be the key that will enable us to develop new oil and gas resources in an environmentally considerate manner. It is of great importance for the Norwegian shelf’s competitiveness and attractiveness that we have access to new exploration areas in the north. The industry must have predictable operating parameters for future exploration, development and production in the Lofoten-Barents Sea area. We will meet the environmental challenges.”