In the early years of the Norwegian oil and gas industry, the oil companies concentrated on developing the largest finds, while smaller fields were considered too expensive to develop.

The oldest and biggest fields involved large-scale development projects, with large platforms standing on the seabed. As development of smaller fields has become more economically viable, less complex installations, such as subsea installations and floating production units, have become more common

Wider areas of seabed are being exposed

There are now 70 fields on stream on the Norwegian continental shelf, most of them in the North Sea. In many cases there are several platforms and other installations on a single field. Some fields have subsea installations and are tied together with other fields.

With so many fields in production and constant expansion, wider and wider areas of seabed are being affected by the installations themselves and by discharges of drill cuttings contaminated with oil and chemicals. 

At the beginning of the oil age in the early 1970s, discharges from drilling contained large amounts of oil and chemicals. The hydrocarbon content of sediments near an oil field could be more than 1000 times the background level, and the impacts could be significant, for example low biodiversity in benthic communities. On some fields, this had an impact on biodiversity across many square kilometres of the seabed.

Reductions in the use of harmful chemicals

The authorities' efforts to eliminate the use of harmful chemicals and reduce emissions have given results. The oil and gas industry now has much less environmental impact than would have been the case if operations had continued unchanged since the early 1970s. Today, the most harmful chemicals have been phased out and the effects on the environment are becoming considerably less severe. Even though the number of installations has risen, there has not been a corresponding increase in the environmental impact on the seabed.

The transition from large, fixed installations to floating production units and subsea developments is particularly contributing to reducing impacts on the seabed. Where possible, more technical installations are also being designed for reuse, which reduces resource use and cuts emissions.

Transport and processing also generate pollution

Further infrastructure is needed to transport processed oil and gas from production platforms to onshore installations. Oil may be transported by shuttle tankers or pipeline, while gas is piped.

Onshore, oil and gas are transferred to larger tankers at terminals, and processing continues at refineries to produce petrol and other products. These products are transported by tankers onshore or at sea.

In addition, a fleet of supply ships is needed to transport equipment, and helicopters to transport personnel to the offshore installations.

All these activities release pollutants and therefore have environmental impacts.

Both in Norway and internationally, much work is being put into the development of technical solutions that use resources more efficiently and generate less pollution – for example, by designing equipment and installations so that they can be reused. It is also important to optimise energy production for offshore use and coordinate energy supplies for different platforms where possible, in order to reduce emissions to air.

There are already technical solutions that make it possible to eliminate major sources of pollution, such as the discharge of drill cuttings and produced water. These must be further developed and taken into use wherever technically and financially possible. The objective is to find solutions with the lowest possible environmental impact. One of Norway's goals is to eliminate releases of substances that may be environmentally harmful to water and air from all activities in the oil and gas sector.