Environment Report 2015

ENVIRONMENT REPORT 2015

Just over 38,000 tonnes of water-based cuttings and around 9,000 tonnes of treated oil-based fluid cuttings were discharged from offshore installations on the UKCS in 2014. This is approximately 12,000 tonnes less than was discharged in total the previous year. There was an increase, however, by nearly 4,000 tonnes of thermally-treated oil-based fluid cuttings discharged, reducing the requirement to ship this waste to shore. Approximately, 7,000 tonnes of oil-based cuttings were injected back into the reservoir (compared with 11,000 tonnes in 2013) consistent with the overall decline in cuttings generated, correlating to reduced drilling activity.

Figure 10: Cuttings Discharged to Sea

70,000

Cuttings from Oil-Based Fluids

Cuttings from Water-Based Fluids

60,000

50,000

40,000

30,000

20,000

10,000

Cuttings Discharged to Sea (Tonnes)

0

2010

2011

2012

2013

2014

Source: EEMS June 2015

There is limited international data publically available on the discharge of drill cuttings, as less than half the IOGP reporting companies provided information on oil-based cuttings in 2013. Norske Olje & Gas reported a 25 per cent increase in the generation of oil-based mud cuttings between 2012 and 2013, none of which were reported as discharged to sea. 3.5 Atmospheric Emissions The extraction, stabilisation and export of hydrocarbons involve several processes that give rise to atmospheric emissions. These include combustion to provide electrical power and drive compressors and pumps; flaring of excess gas for safety and during well testing; and incidental releases from tank loading, as well as firefighting and refrigeration equipment.

Combustion and flaring result in emissions of carbon dioxide (CO 2

), carbon monoxide (CO), methane (CH 4

) and

oxides of nitrogen (NO x

) and sulphur (SO x

). Small amounts of nitrous oxide (N 2

O) are also emitted. Releases of

volatile organic compounds (VOCs) and CH 4

may occur during tank loading, while firefighting may release halons.

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