Environment Report 2019

ENVIRONMENT REPORT 2019

3.5 Chemicals The offshore oil and gas industry uses 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 responsible environmental performance. OPRED must permit all 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 2018, just under 103,500 tonnes of chemicals were discharged to sea (167 tonnes per million boe produced). Sixty-four per cent of this (66,600 tonnes) derived from drilling activities, 34 per cent (35,000 tonnes) from production-related activity, and 2 per cent (1,850 tonnes) were pipeline chemicals. 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. Over the last decade, however, the amount of drilling chemicals discharged has fallen by 35 per cent, in line with the reduction in drilling activity over this period. The spike in 2013 (see Figure 18) is due to more complex wells being drilled and is out of step with the downward trend observed since 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 greater use of chemicals to improve recovery rates, help maintain asset integrity and ensure compliance with environmental permit conditions. In 2018, over 2,600 tonnes more production chemicals were discharged to sea than in 2017 — a rise of 8 per cent. Chemicals used for pipeline maintenance are designed to prevent corrosion or scale build-up. As shown in Figure 18, the amount discharged increased slightly on 2017, and accounted for 2 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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