Assessment of the discharges, spills and emissions from offshore installations on the Norwegian Continental Shelf in 2012-2016

Executive Summary

This report presents the discharge, spill and emission data from offshore oil and gas operations on Norwegian Continental Shelf (NCS) over the period 2012–2016 and the assessment of the data. The annual data is provided in Annex 1.

Level of Activity

The Norwegian Continental Shelf (NCS) is a mature petroleum region. There is still however a high activity level, with 248 wells drilled in 2016 and large discoveries made in the last few years. Total gross production increased with approximately 15 % between 2012 and 2016.

Discharges & spills

The total quantity of dispersed¹ oil (aliphatic oil) discharged to sea from produced water and displacement water increased during the 2012–2016 period.   

Produced water is the main contributor to the oil discharges from the petroleum industry. The volume of produced water discharged increased between 2012 and 2016, mainly due to the increased water production which typically occurs as fields mature. Injection increased some during this period, this is however not reflected in reported discharges because the main contributors to water production on the NCS do not inject or inject very little produced water. Discharge of displacement water remained stable in the assessment period.

The annual average dispersed oil content in produced and displacement water increased over the period. A maximum of five installations on the NCS in any one year failed to meet the performance standard for oil content as an annual average. However, these installations typically had small discharge volumes as they reinjected most of their produced water. The total amount of oil discharged with water exceeding the performance standard was highest in 2014 and 2016 with 10,5 tonnes and 15,7 tonnes respectively, compared to around 3 tonnes the other years during the 2012‐2016 period.

The total number of oil spills to sea showed a reduction of almost 68 % on the NCS between 2012 and 2016., with the largest reduction between 2013 and 2014. The large reduction is mainly a consequense of a clarification in 2013 of the categories oil and chemical spills.

Chemicals

There was a marked increase in total use and discharge of chemicals from 2012 to 2013, mainly due to higher drilling activity. Both use and discharge of chemicals has reduced since, largely following the level of drilling activity. Most of the chemicals used and discharged are non‐substitution chemicals.

The total quantity of chemicals used offshore in 2016 was 398 158 tonnes out of which 71% (wt.) were on the PLONOR list and another 28 % were other non‐substitution chemicals, while 1 % of chemicals were substitution chemicals. There were no use or discharge of LCPA‐substances in 2016.

Total quantity of chemicals discharged into the sea in 2016 was 103 360 tonnes on the NCS. 86,1 % (wt.) of these were listed on the PLONOR list and another 13,8 % were other non‐substitution chemicals. No chemicals were on the LCPA list and 0,1 % were other substitution chemicals. The number and quantity of chemical spills varies over the assessment period and no clear discernible trend is observed.

Atmospheric Emissions

Emissions of CO₂ remained relatively stable across the assessment period, and variations are mostly related to variations in the production levels. NO_x‐ and SO₂‐emissions have reduced in the assessment period, which is mainly explained by reduced activity from mobile units. Reported emissions of methane reduced, mainly due to new emission factors. Emissions of nmVOCs increased between 2013 and 2014, as new methods for measurement and calculation was implemented. The increase is however small compared to the deacresing trend since 2001, in which the reported nmVOC emissions have been reduced due to regulation of emissions from offshore loading, resulting in i.e. implementation of vapour recovery units on the ships.

1. “Aliphatics” and “aromatics” are defined by the reference method set in OSPAR Agreement 1997—16 (Solvent extraction, Infra-Red measurement at 3 wavelengths). In that context, “aliphatics” and “dispersed oil” mean the same thing.