The reduction in discharges of hazardous chemicals to sea from the petroleum activities on the Norwegian shelf continues. CO2 emissions increased in 2007 as a result of commissioning problems with the LNG plant on Melkoya. nmVOC emissions were also reduced, while there was a slight drop in the NOx emissions. A major accidental oil spill on Statfjord A led to a marked increase in the volume of oil to sea in 2007.
This emerges from the operating companies' annual reporting of emissions to air and discharges to sea. The reporting takes place in parallel with the Norwegian Pollution Control Authority (SFT), the Norwegian Petroleum Directorate (NPD) and the Norwegian Oil Industry Association (OLF) in EnvironmentWeb.
Production discharges to sea
Oil production usually leads to produced water. The water volume increases as the fields mature and the reservoirs are drained of oil. In 2007 water production on the Norwegian shelf was 183 million cubic meters. The water volume discharged to sea was 162 million cubic meters, while 27 million cubic meters was injected into the bedrock. This is an increase in the total volume produced and discharged to sea, while the amount of produced water injected has declined slightly.
Oil in produced water
Water that comes up to the platforms with the well stream is either injected back into the reservoir or cleaned and discharged. From 2006/2007 the maximum permissible oil content in water discharged from the installations on the Norwegian shelf was changed from 40 milligrams per liter to 30 milligrams per liter.
The average oil concentration in the produced water discharged to sea in 2007 was 9.5 milligrams per liter measured via the ISO method, in accordance with requirements from the SFT and the Convention on for the Protection of the Marine Environment of the North-East Atlantic (OSPAR). The analysis method employed for the discharges in 2007 have been changed in relation to previous years. This means the results cannot be directly compared.
Further reduced discharges are expected when various cleaning technologies are in full operation. The C-tour and Epcon cleaning technologies, which are the most common new measures, have provided significant reductions in dispersed oil - down to 1.5 - 2 milligrams per liter on some facilities.
Discharge of chemicals
Total consumption of chemicals in 2007 was 432 000 tonnes. Total discharges were 122 000 tonnes, while 84 000 tonnes were injected. Consumption, discharges and injected volume of chemicals is at about the same level as last year.
Chemicals are classified according to the SFT's system in the green, yellow, red or black categories. Chemicals in the green and yellow categories do not have inherent hazardous properties, while chemicals in the red and black categories may only be discharged for weighty technical or safety reasons. The operators are obliged to replace these with more environmentally friendly chemicals.
Following the introduction of the zero discharge objective for oil and hazardous substances in 1997, discharges of black chemicals have been reduced from 228 tonnes to about one tonne in 2007. Discharges of red chemicals have been reduced from 3933 tonnes to 23 tonnes in the same period. The figures confirm that the operators' work on attaining the zero discharge objective on the Norwegian shelf provides results. Storting (Norwegian Parliament) Report No. 26 (2006-2007) states that the zero discharge objective for added chemicals is deemed to have been attained, but that the work on replacing chemicals with less environmentally hazardous alternatives is to continue.
From 2006 to 2007 the discharges of chemicals in the black category was reduced by 66 per cent, while discharges of chemicals in the red category were reduced by 40 per cent.
In 2007 there were 166 accidental discharges of oil, of which 154 were less than one cubic meter. This is an increase of 44 from last year and the highest number of accidental discharges since 2002, when the number of discharges was significantly reduced. The total volume of oil from accidental discharges in 2007 was 4488 cubic meters.
The largest accidental discharge of oil in 2007 took place on the Statfjord field in December. A ruptured loading hose led to about 4400 cubic meters of stabilized crude oil being pumped into the sea. A final report from all subsequent investigations has not yet been completed.
The total number of chemical discharges in 2007 was 109, which is about the same as in past years. The reported total volume of 5415 cubic meters was, however, considerably higher in 2007. This is due to the identification in 2007 of leakage of injected mass in connection with injection of oil-contaminated drill cuttings on the Visund field. This discharge is estimated at 5000 cubic meters. On the basis of a rough characteristic of the contents of the injected mass, it is estimated that about one per cent of the mass is chemicals in the red category and about five per cent is chemicals in the yellow category. The rest is drilled cuttings.
Emissions to air
Carbon dioxide (CO2)
In 2007, total CO2 emissions from the petroleum activities amounted to 13.2 million tonnes. In 2006 corresponding emissions totalled 11.6 million tonnes. The CO2 emissions from the petroleum activities have been relatively stable in the past six years, but increased a lot in 2007 due to commissioning problems at the LNG facility on Melk°ya outside Hammerfest.
According to preliminary figures from Statistics Norway and SFT, total Norwegian emissions of CO2 amounted to 44.9 million tonnes in 2007. The oil and gas industry accounted for 29.4 per cent of the national CO2 emissions last year. The largest source of the CO2 emissions from the oil and gas industry are the turbines on the offshore facilities.
Nitrogen oxides (NOx)
In 2007, total NOx emissions from the petroleum activities amounted to 53 396 tonnes, compared with 54 348 tonnes in 2006. NOx emissions have been relatively stable in the past seven years.
According to preliminary figures from Statistics Norway and SFT, total Norwegian emissions of NOx amounted to 189 638 tonnes in 2007. The oil and gas industry accounted for 28 per cent of the national emissions last year. The turbines on the offshore facilities are the largest source of NOx emissions from the activities.
Volatile organic compounds except methane (nmVOC)
In 2007, total nmVOC emissions from the petroleum activities amounted to 76 194 tonnes. This is a reduction from 2006 when emissions amounted to 79 539 tonnes. Since 2001 the total nmVOC emissions have been reduced by 70 per cent. The reductions have been achieved as a result of investments in new facilities for removal and recovery of oil vapour on storage ships and shuttle tankers.
According to Statistics Norway and SFT, considerable reductions in the nmVOC emissions from oil loading on the shelf have led to national emissions for the first time being lower than the commitments Norway has through the Gothenburg Protocol. According to preliminary figures from Statistics Norway and SFT, total Norwegian emissions of nmVOC amounted to 191 370 tonnes in 2007. This means that the oil and gas industry accounts for 40 per cent of the national emissions.
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