Friday 1 March 2002

Oil and Gas Industry Concludes £6 Million Drill Cuttings Research Programme

The conclusions of a £6 million research programme funded by the UK offshore oil and gas industry to find solutions for dealing with historic accumulations of drill cuttings on the seabed have been released by the UK Offshore Operators Association (UKOOA).

The programme was launched in June 1998 by a consortium of oil and gas companies with cuttings accumulations beneath their offshore installations the legacy of nearly 30 years drilling activity. Over 20 research organisations from around Europe were enlisted in the extensive three-year programme which included cuttings pile surveys, the development of a model to predict the fate of accumulations over time, the assessment of different management options for technical feasibility and a ten-day lifting trial at BPs North West Hutton platform.

The study was carried out in accordance with the principles set out by the OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic and aimed to identify the best environmental practices for dealing with cuttings using the best available technologies (BEP and BAT).

The Industry met annually with stakeholders to review progress and shape the direction of work, while the overall programme was monitored independently by an international group of scientists led by Professor John Shepherd, director of the Earth System Modelling Initiative at the Southampton Oceanography Centre.

The Reports main conclusions are:

* That a comprehensive programme of surveying, sampling, analysis and long-term fate modelling is required to select an environmentally sound management option for a cuttings accumulation;

* That the management options include covering, retrieval and leaving accumulations in place to degrade naturally;

* That a one size fits all approach does not constitute the best environmental option and selection and implementation of the best environmental strategy for drill cuttings should be part of the consideration of the decommissioning programme of an offshore oil and gas installation;

* That the determination of the best environmental strategy will require consideration of both the science of environmental impact and the impact of the cuttings accumulation on other users of the sea. It will also require value judgements around what is and is not acceptable in terms of the various environmental impacts each management option would have on the land, sea and air;

* That these judgements are best made following public consultation.

Ian Silk, chairman of the UKOOA Drill Cuttings Initiative, said: In the light of the discussions at the last stakeholder event in December 2001, it would appear that the best environmental strategy for any particular cuttings accumulation could fall within a range of parameters. Where the impact of the cuttings accumulation on the environment is shown to be insignificant, natural degradation would be the best environmental option. Where the impact is shown to be significant, covering or retrieval of the cuttings would be the best option. Where the significance of the impact is not clear, then all three options would have to be considered.

The study shows that hydrocarbons and hydrocarbon containing materials are the prime contaminants in cuttings accumulations, and that the long-term fate of piles is determined by the physics of ocean currents and wave movement. UKOOA therefore suggests assessing the significance of an accumulations environmental impact by considering:

* the rate of loss of hydrocarbons to the water column;

* the area of the seabed where the biological impact of the cuttings can be measured;

* the rate at which this area changes over time.

UKOOA suggests thresholds which could be used in the assessments, but recognises that local issues such as spawning grounds would need to be considered and emphasises the need for public consultation.

The Reports conclusions were presented at the meeting of OSPARs Offshore Industry Committee in Cadiz earlier this month (February 2002) for their consideration pending a decision on further action.

NOTE TO EDITORS

1. After 30 years of discharges, the total area of seabed covered by cuttings accumulations is estimated to be 1,650km2 or 0.23 percent of the total area of the North Sea. This compares with an area of seabed that is affected by fishing, dredging and spoil dumping of approximately 130,000 to 369,000km2 each year (up to 50 percent).

2. Drill cuttings are small pieces of rock created when a well is drilled in rock to reach oil and gas trapped below. The cuttings are carried back to the surface by the drilling mud, a special fluid used to lubricate and cool the drill bit, and to maintain pressure in the well to prevent blow-outs of oil and gas. At the rig, the cuttings are separated from the mud; as much mud as possible is recycled to be used again and the small rock cuttings are discharged to the seabed, taken ashore for treatment or re-injected into wells.

3. The discharge of cuttings containing traces of mineral oil based muds ceased in 1992 and those containing traces of synthetic muds at the end of 2000. Both types of cuttings are now cleaned and taken ashore for treatment or re-injected into wells.

4. The prime contaminant within the historic cuttings accumulations are hydrocarbons and hydrocarbon containing materials. These represent 4 percent of the total mass of piles.

5. The rate of release of oil from all North Sea accumulations is relatively low and is thought to be of the order of 330 Te/year, which equates to less than 0.5 percent of the total annual input of hydrocarbon from all other countries (around 65,000 Te/year).

6. Potential impacts of other contaminants including heavy metals are very small in comparison with the hydrocarbons and very small in absolute terms too.

7. UKOOAs scientific conclusions are presented in full in the UKOOA Drill Cuttings Initiative Final Report, available from the drill cuttings pages on the UKOOA website at www.oilandgas.org.uk/issues under Environment. Also available are the Scientific Review Group Final Report and links to reports published by the Environment Council following the Stakeholder meetings.

8. UKOOA will shortly publish the UKOOA Drill Cuttings Initiative CD-Rom, a compilation of all the reports relating to the three-year study. Please contact Trisha OReilly at UKOOA on Tel: 020 7802 2422 for a copy.

9. The members of the independent Scientific Review Group are:

* Professor John Shepherd MA, PhD, CMath, FIMA, FRS

* Professor William Dover, FIMechE, CEng, FINDT

* Dr Brian McCartney, BSc, PhD, FIEE, CEng

* Professor Bruce Sellwood, BSc, Dphil, FGS, CGeol

* Dr Hans Temmink

* Professor Dr Jürgen Rullkötter, Dipl.-Chem., Dr. rer. nat. habil., AAPG, DGMK, DGMS, EAOG, GDCh, GS

* Research Scientist Torgeir Bakke, Cand.real. (MSc equiv.) Marine Biology

* Professor Brian Wilkinson BscEng, BscGeol, PhD, FICE, FCIWEM, FGS, C Eng, C Geol, F Russ Acad.Nat.Sci.

For more information, please call 020 7802 2400.