Seabed surveys: The best means to assess the environment impact of drilling fluid discharges?
With the ban in 1984 of the use and discharge of diesel based drilling fluids in the North Sea and their substitution with Low Toxicity Mineral Oils, the Oil and Gas Drilling Industry took an important step forward towards the reduction of the environmental impact of drilling operations. This change to low toxicity OBM was based solely on the lower acute toxicity of these mineral oils to the shrimp Crangon crangon. Unfortunately this substitution did not render the expected results. Although the toxicity of the OBM was considerably lower than that of diesel, the same environmental impact was recorded years after the contaminated cuttings were discharged. It was observed that once the OBM cuttings were discharged, they create a pennanent situation of organic enrichment in the sediment. This is mainly because these oils are biodegraded slowly under aerobic conditions and not biodegradable under anaerobic conditions. These findings prompted the regulatory authorities and environmental agencies, in North Sea countries, to reconsider the information required before granting permits for use and discharge of invert emulsion drilling fluids to the sea. With the introduction in the UK of the revised Offshore Chemical Notification Scheme (OCNS), and more recently the Harmonized OCNF (HOCNF) for all North Sea countries, new additions to the required ecotoxicological information have been made: Toxicity to three species, Biodegradation and Bioaccumulation.
- OSTI ID:
- 414797
- Report Number(s):
- CONF-960623-; TRN: 96:004555-0099
- Resource Relation:
- Conference: International conference on health, safety and environment in oil and gas exploration products, New Orleans, LA (United States), 9 Jun - 12 Sep 1996; Other Information: PBD: 1996; Related Information: Is Part Of The third international conference on health, safety & environment in oil and gas exploration and production. Proceedings - Volume 2; PB: 934 p.
- Country of Publication:
- United States
- Language:
- English
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