Recommend this site to a colleague

click here

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

Learn more ***** ORDER NOW!

Highly recommended by the!

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


The Norwegian State Pollution Control Authority (SFT) regulates the use of drilling fluids/muds through discharge permits. Water based muds are tested under OSPAR formats for bio-accumulation potential and bio-degradability and given a discharge permit if judged to be environmentally friendly. Synthetic muds are similarly evaluated and can be given a discharge permit according to their properties, but at present discharge of SBMs is not allowed north of the 62nd parallel. All oil-based muds are injected or taken to shore for treatment. The discharge of solids containing more than 1% oil, by weight, is forbidden - whether the drilling fluid is water-, oil- or synthetic-based.

There is a specific prohibition on the discharge of "pipe dope" - compounds used to join sections of drill pipe, which often contain high proportions of lead and other heavy metals. The regulations also deal explicitly with well testing, workover and cementing -notoriously polluting procedures:

Discharge of oil to water during well testing in addition to discharge via the process plant, is prohibited. Separation fluid contaminated with oil may not be discharged.

The operator must assess and where necessary choose disposal solutions other than burning of the fluid phase in the well stream during well operations (well cleaning, testing, workover, etc.).

The operator shall consider measures that can reduce the discharge of excess cementing chemicals during cementing work, e.g., by choosing methods of disposal other than discharge of the excess or adapt the equipment and routines with a view to minimising the excess volumes.

Norwegian regulations (See: 1. Norwegian State Pollution Control Authority [SFT]. 1998. Requirements for Ecotoxicological Testing and Environmental Assessment of Offshore Chemicals and Drilling Fluids. SFT, Oslo; 2. Norwegian State Pollution Control Authority [SFT]. 1999a. Environmental Monitoring of Petroleum Activities on the Norwegian Shelf; Guidelines 99:01. SFT, Oslo; 3. Norwegian State Pollution Control Authority [SFT]. 1999b. Pollution Control Act, 1981. SFT, Oslo) are just as detailed and specific as those in the UK, but requirements appear to be more stringent and enforcement more rigorous, although there is still considerable reliance on self-regulation and self-reporting by the industry. As of 1 Sept. 1998, Norway's general conditions for permits to discharge offshore (in addition to specific requirements for each installation and/or field) included the following:

  • A 40mg/l limit for oil in discharged water, averaged over a month, with a specific prohibition on diluting produced water before a sample is taken for analysis. This appears to suggest that such pre-sampling dilution may have been a problem in the past.

  • Water and mud purification plants to be operated to "optimum environmental effect" - in other words, if the equipment makes it possible to do better than the official standard, then that is what should be done.

  • Detailed specifications for sampling and laboratory analysis of samples - including "parallel samples" sent to independent laboratories, as a check on the validity of the operator's own testing.

  • Annual, independent assessment of each operator's sampling and analytical techniques.

  • Detailed records of the quantities of produced water discharged.

  • On-line analysers for oil in water are compulsory, with spot checks on parallel samples five times a month, to check that the on-line equipment is properly calibrated.

  • Independent samples, once a week, of produced water re-injected.

  • Separate sampling and analysis of aromatic hydrocarbon components in produced water, again with parallel samples for independent, monthly checks by infra-red equipment.

Norway uses the standard OSPAR "A" and "B" lists for offshore chemicals and requires that discharge of these "shall be reduced as much as possible, e.g., through recycling". Operators are required to ensure the purity of the substances they use, with minimum contamination by other chemicals. Discharge of unused chemicals into the sea is expressly forbidden, even if they are on list A or B and their toxicity is therefore well known. All discharges must have a permit and chemicals not on the lists must be separately tested and notified.

The following tables show the A & B lists of offshore chemicals currently permitted in Norway, which is generally considered to be the most stringent regulatory environment in the OSPAR countries:

Table 4: SFT List A chemicals

Acetic acidAluminium silicate
Aluminium sulphate Ammonium acid phosphate
Ammonium bisulphate Ammonium chloride
Ammonium hydroxide Ammonium sulphite
Amylase (25%)/amlylopectin polymer (75%) (only as a preservative for pregelatinised starch with a maximum concentration of 5%)*) Ascorbic acid
Attapulgite clay Barite with lowest levels of trace metal impurities (weighting agent)
Barium sulphate Bentonite (weighting agent)
Butanol Calcium bromide
Calcium carbonate (weighting agent) Calcium chloride
Calcium hydroxide Calcium lignosulphonate
Calcium nitrate Calcium oxide
Calcium sulphate Calcium phosphate
Carboxymethyl cellulose Carboxymethyl hydroxyethyl cellulose
Causticized lignite Cellulase
Cellulose fibre Cement grade G
Citric acid Cornstarch
Cotton seed hulls Diatomaceous earth
Dicalcium silicateDolomite (weighting agent)
Ethanol (rendered undrinkable) Ethyl cellulose
Ferric sulphate Ferrous carbonate
Finely divided iron oxide Formic acid*)
Glass beads Glycerine
Graphite Guar gum
Gypsum 2-Hydroxyethyl ether cellulose
Hydroxyethyl cellulose Hydroxypropyl Guar gum
Ilmenite (weighting agent) Iron carbonate
Iron lignosulphonate Iron oxides (weighting agent)
Isopropanol Kaolin
Lactose Lecithin
Lightly calcined magnesium hydroxide Lightly carbonated magnesium hydroxide
Lignin Lignite
Lime Limestone
Magnesium chloride Magnesium hydroxide
Magnesium oxide Manganese tetraoxide (weighting agent)
Methanol Mica
Monoethyleneglycol Nutshells
Olive pits Polysaccharide
Potash Potassium bicarbonate
Potassium carbonate Potassium chloride
Potassium nitrate Potassium phosphate
Pre-gelatinised potato starch Propanol
Pyrophosphate Silica gel
Silica sand Silicon dioxide
Soda ash Sodium acetate
Sodium benzoate Sodium bicarbonate
Sodium bisulphite Sodium borate
Sodium bromide Sodium carbonate
Sodium carboxymethyl cellulose (or CMC) Sodium chloride
Sodium lignosulphonate Sodium nitrate
Sodium nitrite*) Sodium phosphate
Sodium silicate Sodium sulphite
Sodium tetraphosphate Sodium thiosulphate pentahydrate
Sorbitol Starch (untreated)
Sugarcane molasses Tricalcium silicate
Vegetable fibre Vermiculite
Wood fibres Xanthan gum

Table 5: SFT List B chemicals

AcetoneCalcium Stearate
Diethyleneglycol Ferric chloride
Formaldehyde Glutaraldehyde
Hydrochloric acid Metasilicate
Potassium iodidePotassium hydroxide
Phosphoric acid Sodium hydroxide
Sodium hypochlorite Triethyleneglycol

Go to Previous Page: United Kingdom Law on Offshore Wastes Discharges continued

Go to Next Page: Canada Law on Offshore Wastes Discharges

Back to Home Page

[Author] [Conclusions] [Drilling Waste] [International Law] [Environmental Effects] [Minimizing Discharges] [Resources] [References]

Contact us if you have any questions or want to contribute an article:

"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


Order Now




Interesting facts

Internet Resources

Take a break :)