Environment Report 2017

Produced Water Composition Produced water accumulates small amounts of naturally occurring substances through contact with the reservoir rock, including dispersed oil, dissolved organic compounds and naturally occurring radioactive materials (NORM). Trace production chemicals are also present. If discharged with produced water, these chemicals rapidly dilute within the marine environment. The type and composition of chemicals produced are determined by the reservoir geology, maturity and production life stage. Oil in Produced Water Around 2,000 tonnes of oil were discharged to sea with produced water, making up just over 0.001 per cent of the total mass of produced water. This is down 4 per cent from 2015 despite the 5 per cent production increase over the same period. OSPAR Recommendation 2001/1 requires that individual installations do not exceed an average oil in water concentration of 30 milligrammes per litre (mg/l). In 2016, the average concentration of oil in produced water across industry was 13.3 mg/l, down from 14.9 mg/l in 2015. This maintains the general trend since data have been recorded using the GC-FID method, in place since 2007. At such low concentrations, oil rapidly disperses and is quickly broken down by naturally occurring bacteria.

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International Comparison The concentration of oil in produced water on the UKCS remains comparable to global and Norwegian values. The global average was 11.4 mg/l in 2016, while Norwegian data 6 show concentrations of 12.3 mg/l.

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Figure 3: Oil Discharged with Produced Water to Sea

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Oil Discharged with Produced Water

Average Oil Content with IR Method

Average Oil Content with GC-FID Method

Oil in Water Concentration Limit

8

7,000

35

)sennoT( retaW decudorP htiw degrahcsiD liO

6,000

30

9

5,000

25

4,000

20

10

3,000

15

2,000

10

11

1,000

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Oil in Water Content (Milligrammes per Litre)

0

0

2009

2007

2008

2006

2005

2004

2014

2003

2013

2001

2002

2012

2016

2000

2011

2015

2010

Source: EEMS July 2017

6 See Norsk Olje & Gass Environmental Report 2017 at http://bit.ly/NorskEnvironRep17

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