Environment Report 2017

Figure 34: Mass of Accidental Chemical Releases by Hazard Category and Number of Releases

1

1,000

Unattributable High Medium Low PLONOR Number of Releases

900

2

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800

700

3

600

500

4

400

300

200

5

100

0

6

2010

2011

2012

2013

2014

2015

2016

Source: BEIS July 2017

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Releases by Source The accidental chemical releases from 2010-16 are also categorised by source. Figure 35 overleaf shows annual variation, highlighting the anomalous, largest incidents over the last five years and reflecting the unplanned nature of the releases. Between 2010 and 2016, production systems and related equipment contributed the majority (1,132 tonnes, 36 per cent) of all accidental chemical releases. Over half of this (651 tonnes) was released during just four incidents. Hydraulic and subsea systems accounted for 657 tonnes and 523 tonnes (21 per cent and 16 per cent), respectively. Together, these three categories account for over 72 per cent of accidental releases by mass over the past seven years. Other notable releases occurred in 2012 when 364 tonnes of oil-based drilling fluid were released following a wellhead blowout and, in a separate incident, 139 tonnes of water-based drilling fluid were released from a wellbore. In 2016, there were eight releases over ten tonnes from four sources: two from hydraulic systems, four from pipework infrastructure, one from containment and one for which the information was not sufficient to attribute to a source category. The largest of these releases related to a failure of containment when the fluid return system on a drilling rig overflowed.

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9

10

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Where precise amounts are not known, which is often the case when releases are accidental, operators provide worst-case estimations for each incident and so the actual amount released is likely to be less.

Figure 35 also shows the increase in the number of releases since 2010 in contrast to the overall decrease in release mass, demonstrating that individual releases are on average getting smaller each year.

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