Environmental challenges in the operating phase

22.04.2014

The NPD contributes to the fulfilment of Norway’s environmental and climate policy goals. Environmental regulation covers all stages of the industry. It applies when considering whether an area is to be opened for petroleum activities and, later, during exploration and field development. When a field has been developed, environmental assessments are important for specific operational permits, for annual changes to permits, and until cessation of production and disposal of the facilities.

Through the policy framework, the choice of players and technology, and continuous follow-up of activities, the government helps to ensure that requirements are observed and environmental goals attained.

 

4.1 Emissions to the air

CO2 and NOX account for the bulk of emissions. Figure 4.1 presents historical carbon emissions and forecasts up to 2020. Emissions are expected to rise somewhat over the next few years before stabilising thereafter.

Figure 4.1

Figure 4.1 Historical emissions and emission forecasts for CO2 to 2020.

 

Most of the power required on the NCS is provided by gas turbines. As figure 4.2 shows, about 80 per cent of emissions derive from energy production by turbines. Flaring comprises some 10 per cent and engines eight per cent. The Petroleum Act forbids flaring of petroleum in normal operation other than for necessary safety reasons. Safety flaring is regulated by the production permit.

Figure 4.2

Figure 4.2 Carbon emissions by various combustion sources. Other sources comprise boilers, well testing and direct emissions.

 

Figure 4.3 presents historical NOX emissions and forecasts up to 2020. These emissions are expected to be stable over the next few years.

Figure 4.3

Figure 4.3 Historical emissions and emission forecasts for NOX to 2020.

 

NOX emissions derive primarily from engines and turbines on the facilities. See figure 4.4. Turbine operation contributes about 60 per cent. All new production facilities brought into operation on the NCS since 2000 have low-NOX turbines installed. Low-NOX turbines fuelled only by gas are regarded today as the best available technology (BAT). These turbines reduce NOX emissions by 50-90 per cent compared with conventional gas turbines. Low-NOX turbines which can run on both gas and diesel have been operating on the NCS since 2008.

Figure 4.4

Figure 4.4 NOX emissions by source. Other sources comprise boilers and well testing.

 

Total emissions from fixed installations have declined gradually since 2000, while those from mobile units are increasing. The latter primarily meet their power requirements from diesel engines. Many new developments do not have permanent drilling rigs, but use mobile units for drilling and heavier well maintenance.

One method which could help to reduce carbon emissions from the NCS would be to supply more of the power required to operate offshore facilities from the electricity grid on land. Several fields receive or are planned to obtain power from shore. These are Valhall, Martin Linge, Troll A and Gjøa in the North Sea and Goliat off Finnmark. The Johan Sverdrup licensees have chosen a concept based on power from shore for phase I of the development.

The Storting (parliament) requires power from shore to be assessed for all new developments and major conversions of producing fields. Such studies are assessed by the NPD. The abatement cost of installing power from shore on facilities varies considerably between different developments. Features which make this approach more cost-effective include closeness to land, a limited need for process heat, a substantial demand for power, a large electricity grid in the region, and a long producing life for the field.

 

4.2 Produced water

The volume of produced water has been stable, but is expected to rise somewhat over the next few years. See figure 4.5. In spite of stable production, discharges of produced water have declined somewhat in recent years, reflecting increased produced-water injection on certain fields. The operators have developed treatment capacity for produced water as discharge restrictions have become tighter.

 

Figure 4.5

Figure 4.5 Historical volumes and forecasts for produced water and discharges.

 

Water which accompanies oil and gas production from the reservoir comprises natural supplies from the formations and possible water injected to improve recovery. It is separated from the oil and gas and treated in the process facility. After treatment, formation water still contains some dispersed oil as well as dissolved organic and inorganic compounds. Produced water can also contain residues of various chemicals added to the process. The volume and composition of produced water can vary a great deal from field to field, and over a field’s producing life.

In the years leading up to 2000, work was initiated to reduce the risk of damage from increasing discharges of produced water. The target was zero harmful discharges. These efforts led in part to the development of new treatment technology, and new chemicals replaced potentially harmful substances. Over a 10-year period, more than 95 per cent of the chemicals with a potential to harm the environment were replaced. The zero discharge target is regarded as having been attained for environmentally hazardous chemical additives. The petroleum industry accounts for only a small proportion of discharges involving substances on the priority list drawn up by the environmental authorities for phasing out environmental toxins. Efforts to reduce discharges of such substances are continuing. These substances will continue to be used and discharged to the sea to a limited extent in coming years for safety and technical reasons.