Environment Report 2018


3.3. Chemicals The offshore oil and gas industry uses and discharges chemicals in the exploration and production of hydrocarbons. Usage is kept strictly to the amounts required for the designated task to avoid waste and ensure a responsible environmental performance. OPRED must permit all use and discharges in advance, and operators are obliged to continually review the volume and the types of chemicals they use. Only chemicals that have been registered with the Centre for Environment, Fisheries and Aquaculture Science’s (CEFAS) Offshore Chemical Notification Scheme (OCNS) are permitted for use and discharge. The OCNS applies the OSPAR Harmonised Mandatory Control Scheme (HMCS), developed through OSPAR Decision 2002/2 (as amended by OSPAR Decision 2005/1) and its supporting recommendation. The OSPAR HMCS contains a list of chemicals that it considers to ‘Pose Little Or NO Risk’ (PLONOR) to the environment, as well as those for which there is a substitution warning (SUB) where a less environmentally hazardous alternative should be used if practicable. Mass of Chemicals Discharged In 2017, just over 96,000 tonnes of chemicals were discharged to sea (154 tonnes per million boe produced). Sixty-five per cent of this (62,170 tonnes) derived from drilling activities, 34 per cent (32,383 tonnes) from production-related activity, and 1 per cent (1,524 tonnes) were related to pipeline activity. The mass of chemicals discharged is dominated by drilling chemicals. These are used in drilling fluids and cement, which are important for safety and well control. Since 2000, however, the amount of drilling chemicals discharged has fallen by 42 per cent, in line with the reduction in drilling activity over this period. The spike in 2013 (see Figure 5) is due to more complex wells being drilled and is out of step with the downward trend from 2010. Although UKCS production has been in decline since 2000, there has been a gentler fall in the use of production chemicals. This is because of the basin’s maturity, which requires chemicals to improve recovery rates, maintain asset integrity and ensure compliance with environmental permit conditions. In 2017, nearly 3,000 tonnes more production chemicals were discharged to sea than in 2016 — a 10 per cent rise. Chemicals used for pipeline maintenance are designed to prevent corrosion or scale build-up. As shown in Figure 5, the amount discharged decreased year on year, and accounted for 1 per cent of total chemicals discharged. As with drilling activity, pipeline works will fluctuate from year to year and chemical discharge will largely reflect this.


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