Environment Report 2016

Figure 6: A Breakdown of Pipeline Chemicals Discharged by Classification

1

3,000

Pipeline Other*

2

Pipeline SUB

2,500

Pipeline PLONOR

2,000

3

1,500

4

1,000

Chemical Discharge (Tonnes)

500

5

0

2011

2012

2013

2014

2015

* Other includes those chemicals reported in EEMS that are not classified as PLONOR or SUB but all chemicals have a permit to be discharged.

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Source: EEMS July 2016

By comparison, just over 157,000 tonnes of chemicals were discharged on the Norwegian Continental Shelf in 2015, a slight decrease on 2014 when 166,000 tonnes were discharged 23 . Of those, 91 per cent fell into the green category (chemicals considered to have no or limited environmental impact) and red and black 24 made up 0.046 per cent of the total discharged (67 tonnes and 6.6 tonnes, respectively). 3.3 Drill Cuttings Drill cuttings are rock fragments generated during well drilling offshore. These are carried back to the surface by a drilling fluid. Drilling fluid can either be water-based or oil-based and is reused on the rig after separation from the cuttings. The cuttings, which are coated in drilling fluid, are disposed of according to the type of fluid – water- or oil-based. The choice and composition of drilling fluid depends on the characteristics of the rock strata and consideration of the safety and environmental risks. Oil-based fluid is likely to be used in technically challenging sections of the well, or where a well is being drilled at an angle rather than vertically. Water-based fluid drill cuttings are generally permitted to be discharged to sea. Since 2001, following OSPAR decision 2000/3, oil-based fluid cuttings cannot be discharged to sea unless they are treated to reduce the oil content to below 1 per cent of the total mass. In advance of any discharge, operators must conduct an assessment to investigate the potential environmental effects as part of their permit application to BEIS.

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23 See http://bit.ly/NOGevn16 24 See http://bit.ly/OsparR14

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