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Environmental Impact of the Offshore Oil and Gas Industry by Stanislav Patin - a unique summary of world-wide studies on the environmental issues associated with offshore oil and gas exploration and development

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Muddied Waters

A Survey of Offshore Oilfield Drilling Wastes and Disposal Techniques to Reduce the Ecological Impact of Sea Dumping

by Jonathan Wills, M.A., Ph.D., M.Inst.Pet., for Ekologicheskaya Vahkta Sakhalina (Sakhalin Environment Watch); 25th May 2000

The Law on Offshore Wastes Discharges in Different Jurisdictions

United Kingdom

The United Kingdom has by far the largest numbers of offshore installations in the OSPAR area (See Appendix 1) and, as might be expected, the largest quantity of reported drilling waste discharges. (See Appendices 4, 7 and 8) However, the UK also has a far higher percentage of the total OSPAR discharges than its proportion of the drilling activity would suggest, compared with countries such as Norway, Denmark, Germany and the Netherlands, whose reported discharges are lower than the number of installations in their jurisdictions would suggest. (See Appendices 4,6 and 10) Either the other countries are not accurately and honestly reporting their discharges, or else they are operating a more rigorous enforcement regime. The latter seems more probable. A major cause of the startling contrasts in environmental performance is the difference in political cultures. While some other OSPAR countries appear to take regulation seriously, the UK for years has been content to talk to industry about it, at length, while not actually enforcing compliance on site. There is no other possible conclusion from a close study of the OSPAR statistics.

At present WBM discharges on the United Kingdom Continental Shelf (UKCS) are regulated under voluntary, "guideline" agreements with industry, through the Offshore Chemical Notification Scheme. However, the Department of Trade and Industry specifically warns applicants that the use of "organic lubricants" (i.e. oils or emulsions that don't mix with water) in WBM formulations will be "subject to close scrutiny", even if less than 5% of the total mud weight, and permission is "unlikely" if the individual components are "organic base fluids" already proscribed or restricted under other parts of the OCNS scheme. (CEFAS. 2000a. Guidelines for the UK Revised Offshore Chemical Notification Scheme in Accordance with the OSPARCOM Harmonised Offshore Chemical Notification Format. London)

The industry's assessment of current British standards on WBM discharge is summarised by the UK Offshore Operators' Association (UKOOA) as follows:

WBM discharge is allowed, subject to a 5% limit on organic material. All the evidence is that the discharge has no environmental effect, beyond the potential for smothering if currents do not disperse the material. The volumes of WBM used in drilling a well are much higher as this is the fluid used in the largest [diameter] well sections closest to the seabed surface. Containment would be technically difficult as you have to start the well with some fluid and lifting all WBM for transportation or re-injection would be difficult and involve considerable energy usage. It seems almost inevitable the environmental impacts of the cuttings handling would far outweigh any benefits. (UKOOA spokesman, Aberdeen. April 2000, pers. comm. )

As noted above, this balancing of overall environmental effect, including impacts on the atmosphere and land as well as on sea life, is currently being assessed in the OSPAR committees. The same arguments are being examined in US Environmental Protection Agency's rule-making consultation currently under way (see discussion below).

In general, the United Kingdom follows OSPAR regulations closely although, as mentioned above, the British Government currently proposes new controls on WBMs and is banning discharges of SBMs, going further than some other OSPAR signatories. OBM is currently used offshore but either brought back to shore for disposal or re-injected offshore.

The UK authorities require exhaustive details of every proposed well and operate a system of Petroleum Operations Notices (PONs) to regulate what operators can and cannot do. (United Kingdom Department of Trade and Industry, Oil and Gas Directorate. 1999. Guidance Notes on the Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) Regulations 1999. Edition 2, March 1999. HMSO, London)

Most developments except very minor ones must have an Environmental Statement from the operator. These statements are also normally required in British waters if:

  • The distance to the coast from the well is less than 21.6 nautical miles (40 kilometres);
  • There is a Special Area of Conservation (SAC) or Special Protection Area (SPA) within 40 kilometres of the well;
  • There are concentrations of birds regarded as internationally important within 20 kilometres of the well.

They may also be necessary if:

"Muddied Waters":



List of Abbreviations

Summary of Conclusions

Drilling Waste Streams from Offshore Oil and Gas Installations

The Law on Offshore Wastes Discharges in Different Jurisdictions:

The OSPAR Convention

United Kingdom



United States

Inviting Regulation

Environmental Effects of Drilling Waste Discharges

The SBM Controversy

"Non-Water Quality Environmental Impacts"


Drill Cuttings

Produced Water

Minimising Waste Discharges and Their Effects

Reinjection Offshore

Cleaning Produced Waters

List of Main Sources

Selected References



Articles on Offshore
Oil&Gas; and Environment

Impact of Offshore Oil&Gas; Industry


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