Environment Report 2014

ENVIRONMENT REPORT 2014

Produced water is sampled daily offshore for hydrocarbon concentrations and the results are recorded in the EEMS database. On the UKCS, hydrocarbon concentration levels have been declining since 2000. OSPAR recommendation 2001/1 requires that individual installations do not exceed an oil-in-water concentration of 30 milligrammes per litre (mg/l). In 2013, the average concentration on the UKCS was half this at 14.35mg/l, measured using the GC-FID method 5 , and is lower than the average over the year in 2012. The OSPAR Quality Status Report (QSR) 2010 6 stated that the oil discharges in produced water have fallen on average by 20 per cent from 2000 to 2006 in the OSPAR area through investment in separation technologies as well as reinjection projects. There was a small variation in the average monthly concentrations of oil-in-water discharged in 2013 from 12.90 to 16.68 mg/l. No correlation was found between hydrocarbon concentration in produced water and levels of production or summer maintenance activity.

Figure 3: Oil Discharged with Produced Water from 2000 to 2013

Oil Discharged with Produced Water

Average Oil Content with IR Method

Average Oil Content with GC-FID Method

Oil in Water Concentration Limit

7,000

35

6,000

30

5,000

25

4,000

20

3,000

15

Tonnes

2,000

10

Milligrammes per Litre

1,000

5

0

0

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Source: EEMS June 2014

5 Up to 2006, oil concentration in produced water was measured using the infrared method (IR). The IR method measures with solvent both the dispersed and dissolved hydrocarbons extracted. The method can, however, include other organic chemicals, giving an artificially high result and can also underestimate dissolved hydrocarbons. To rectify this and to provide a more accurate analysis of hydrocarbon content, OSPAR agreed (Agreement 2005-15) the use of a new method for oil-in-water analyses, based upon a modified version of the ISO 9377-2 (GC-FID) method. 6 The OSPAR Commission’s Quality Status Report 2010 is available to download at http://qsr2010.ospar.org/en/index.html

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