Environment Report 2014

3.2.3 Potential Environmental Impacts of Produced Water It is possible to measure concentrations of hydrocarbons in marine sediments. Analysis from Marine Scotland Science in 2010 7 found that poly-aromatic hydrocarbon concentrations in offshore and coastal sediments around the UK are close to background concentrations. Monitoring from Oil & Gas UK from 2006 to 2009 on random sediment samples also indicated that hydrocarbon concentrations are at background levels. This indicates that discharge of hydrocarbons from offshore installations is not resulting in increased concentrations within seabed sediments beyond the immediate vicinity of the installation. Discharge volumes of produced water and concentrations of hydrocarbons from the UKCS are comparable with those from the Norwegian Continental Shelf (NCS) 8 . In 2013, a ten-year study (PROOF and PROOFNY projects 9 ) was completed in Norway on the effects on the marine environment of oil and gas operational discharges. The study investigated areas such as biomarker, endocrine and reproductive effects on certain individuals of species, such as haddock, cod and mussels, that live in close proximity to produced water outlets. The evidence gathered suggests that the effects of produced water discharges are local, in general confined to within one to two kilometres of the outlet, and that the risk of widespread impact is low. Whilst effects could be detected in individuals, no effects were found on the population or community scale. 3.3 Chemical Discharges Chemicals are used offshore in the exploration and production of hydrocarbons. The chemicals can be divided into three categories according to their application. 1. Drilling Chemicals Drilling fluids (‘mud’) are used to lubricate the drill bit and drilling assembly and facilitate the removal of rock fragments during the drilling of wells. They also help to control pressure in the well. The largest component is water but the fluids may also contain organic phase fluids, weighting agents and acidity control chemicals, and they are generally recycled and only discharged when permitted. 2. Production Chemicals Specialist chemicals are used to produce oil and gas to maintain equipment integrity and optimise production. These chemicals include demulsifers to improve separation of oil from water; corrosion inhibitors to protect equipment; scale inhibitors to slow down the build-up of scale in pipework; and valves and biocides to reduce marine growth on equipment. Maintaining equipment integrity is critically important for the safety of offshore workers and to protect the environment. Industry discharges the residues of used chemicals under permit to the marine environment with the produced water. Cement and cement additives are also used in the drilling of wells and occasionally discharged with prior approval from DECC.

1

2

3

4

5

6

7

8

7 Scotland’s Marine Atlas is available to download at www.scotland.gov.uk/Publications/2011/03/16182005/0 8 A report on the Norwegian petroleum sector is available to download at http://npd.no/Global/Engelsk/3-Publications/ Facts/Facts2013/FACTS_2013.pdf 9 More information on the project group PROOFNY can be found at http://bit.ly/PROOFNY

page 13