Environmental Sustainability: Case Studies

Managing priduced water discharges

Oil Discharge Standards

A 40mg/l target for oil-in-produced-water was fi rst introduced by the Paris Convention in 1974, becoming an OSPAR standard in 1992. This was implemented in the UK through the Prevention of Oil Pollution Act 1971. In 1998 UKOOA member companies made a commitment to achieve 30mg/l company annual average oil-in-produced-water.

OSPAR agreed Recommendation 2001/1 'Management of Produced Water from Offshore Installations' in pursuit of reducing pollution of the maritime area. The overall goal of the recommendation is to:

• Reduce the input of oil and other substances into the sea resulting from produced water, with the ultimate aim of eliminating pollution from those sources
• Ensure that an integrated approach is adopted, so that reduction is not achieved in a way that causes pollution in other areas
• Ensure that effort is made to give priority to actions related to the most harmful components of produced water

To implement these goals, each Contracting Party, which includes the UK, is to ensure that:

• The total quantity of oil-in-produced-water discharged to the sea in 2006, from all offshore installations under their jurisdiction, has been reduced by a minimum of 15% compared to 2000
• By the end of the year 2006 no individual offshore installation exceeds 30mg/l for oil-in- produced-water discharged to the sea
• From 1 January 2002, plans to construct new offshore installations should minimise such discharges and, where appropriate, achieve zero discharges

It is important to appreciate that the need for a reduction, or the magnitude of the reduction, was not supported by any scientific evidence suggesting that oil discharged with produced water has a measurable impact on the marine environment. In fact the 15% figure was arrived at through discussion and compromise.

Implementation in the UK

The DTI have committed to achieving the requirements of the Recommendation and will do so through permits issued under the newly introduced Oil Pollution Prevention and Control, OPPC, Regulations. As the required reduction is a national one, UKOOA has been in lengthy discussions with DTI to achieve compliance in the most cost efficient way for the industry as a whole. As a result, the OPPC Regulations enable a trading scheme to be established.

In essence, each installation discharging produced water will receive allowances equivalent to their reported discharges in 2000 less 15% and a 30mg/l concentration limit. The operator of the installation then has the choice of implementing capital projects to achieve the reduction, cutting production to reduce discharges or buying surplus allowances from other operators who have reduced their discharges more than 15%.

So that new installations can obtain allowances, existing installations will have to achieve a 17% reduction to generate surplus allowances. Using current forecasts, the industry will actually have to achieve a reduction of 28% on projected business-as-usual discharges for 2006. To ensure that operators comply with permit conditions the DTI intend to impose a civil penalty, payable for each tonne of oil discharged but not covered by an allowance. The penalty is currently set at £280,000 per tonne of oil.

The capital cost of achieving a 15% reduction for the UKCS is estimated to be £250 million over five years and may be considerably more if a trading market does not develop and operators are forced into paying the penalty or reducing production.

Policy Studies Institute Report

As outlined in the strategy section above, the Policy Studies Institute, PSI has undertaken a study of the management of produced water using flow analysis methodology. This draws several conclusions, which are summarised below:

• Overall, evidence does not demonstrate that any harm is being caused by discharges of produced water in the North Sea. However, there is sufficient uncertainty associated with the risks from some components of produced water to warrant further investigation
• Evidence suggests that the main risk factor from produced water is the concentration rather than the total discharge volume
• As there has been no harm demonstrated by field studies, the 30mg/l limit would seem to represent a sensible precautionary approach
• Whilst the 15% reduction will reduce the quantity of hazardous substances discharged, this is arbitrary with no evidence that it would achieve a meaningful reduction in environmental risk but would impose its own environmental burden and cost
• It is not currently technically feasible to remove completely hazardous substances from produced water and the burden of reducing discharges to zero (by re-injection) might outweigh the benefits i.e. injection of each tonne of oil will release 200-800 tonnes CO2

The study recommends additional research:

• Toxicity and toxicity identification of produced water at high concentrations (e.g. of the occurrence of alkyl phenols)
• Investigation of the interaction between the biological reef effect around installations and the produced water plume, which could potentially lead to contamination of sediments/ biota and the bioaccumulation in fish (e.g. as part of a monitoring strategy)

Field Studies

In collaboration with the DTI we have sponsored a two year study to identify potentially harmful components in produced water using the Toxicity Identifi cation and Evaluation technique. Further work to assess the risks to the marine environment will be initiated if the results indicate the presence of substances of concern.

A monitoring strategy for the industry is being developed with input from all the regulators and their advisors. The 2005 sampling programme includes the analysis of hydrocarbon contamination patterns in sediments and seabed dwelling biota away from offshore installations, contamination in mussels growing on offshore installations and an investigation into changes in benthic community structure.