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

Environmental Effects of Drilling Waste Discharges (continued)

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The Effects of Discharges of Produced Water (continued)

The Russian practice of stationing independent, expert inspectors on such installations as Molikpaq appears, by comparison, a much more rigorous and scientifically reputable approach - assuming that there is no attempt by commercial interests to intimidate or suborn the inspectors. When such very large sums of money are involved in projects, that is always a possibility. If harassment, corruption and environmental law-breaking can happen on the North Slope of Alaska (vide the Doyon Drilling scandal at the Endicott oilfield, discussed above) then it might be attempted on the Sakhalin Shelf if, for example, there were a pressing need to get rid of quantities of toxic waste at night or during a storm. It is assumed that the Russian regulatory authorities are well aware of the necessity to guarantee the independence (and personal safety) of offshore inspectors, and that they will make every effort to do so.

Former civil servants who now work for the oil industry (and even some who have not yet made the career move) often remind us how important it is to keep things in proportion when discussing marine pollution. They are right to do so. The E&P; Forum study referred to above found that only about 4% of the total oil spilled into the North Sea came from produced water discharges. Although dwarfed by oily run-off from the land into rivers and estuaries, or the large quantities of bilge oil still dumped into the sea by ships of all sizes (fishing vessels being particularly notorious culprits in this regard), the offshore oil and gas installations' contribution is still significant and justifies measures to reduce it further, as the industry's continuing statements of concern about the problem appear to demonstrate.

The 1994 E&P; Forum report concluded that produced water discharges in the North Sea had "a low potential for biological impacts" because of low concentrations and low toxicity of the pollutants, rapid dilution and rapid reaction with seawater. "All produced waters can be classified as 'practically nontoxic' according to the European Community addepted [sic] hazard rating," the authors stated. "Produced water appears to exhibit no toxic effects in the field... In the far field there is no discernible impact."

The dilutions required for No Observed Effect Concentration (NOEC) were achieved at "from 10 to 100 metres" from discharges and within five minutes. As a result, acute toxic effects on living things were "unlikely to occur" because exposure times were too short. "Through a number of complex mechanisms, the components of produced water are removed from the water column," the authors explained. "The fate of soluble organic components is biodegradation while insoluble components are subject to transport and sedimentation..."

They did, however, acknowledge that more research was required on the amounts, fates and effects of toxic heavy metals in produced water - which, according to the E&P; Forum estimates, contributed about 3.3% of the total heavy metal input from human activities. Another suggested research topic was how the characteristics of produced water change as a field ages, and also the fate and effects of the lighter hydrocarbons in dispersed oil.

UKOOA holds a similarly reassuring opinion:

In addition to laboratory tests which show that produced water is not toxic to marine life, the profuse growth on submerged structures and the large populations of fish that inhabit the waters below offshore installations provide ample evidence that produced water discharges do not adversely effect marine life... Long term or chronic effects are also very unlikely given the miniscule levels of contaminants in produced water discharged. (United Kingdom Offshore Operators' Association. 1999b. 1999 Environmental Report. Website: http://www.ukooa.co.uk/issues. London)

Greenpeace authors, on the other hand, point out that conventional measures of oil in produced water, such as those used to date by OSPAR, "take no account of the aromatic hydrocarbons, including the very toxic polynuclear aromatic hydrocarbons (PAHs)" which are dissolved in produced water and are unlikely to be removed by treatment before discharge. (Reddy, S. et al. 1995. op cit.) The oil carried in produced waters is more toxic than in the petroleum itself, they argue, because these fluids are "enriched in aromatic hydrocarbons which are the most soluble and toxic fractions of crude oil". (Quoting Lysyj, I. G., et al. 1981. Effectiveness of Offshore Produced Water Treatment. In Proceedings of the 1981 International Oil Spill Conference, pp.63-67. American Petroleum Institute, Washington, D.C.; and Neff, J. M. 1987. Biological Effects of Drilling Fluids, Drill Cuttings and Produced Waters, in Boesch, D. F. and Rabalais N. N. (eds.). 1987. op. cit.) As a result, the oil content of produced waters from oil platforms could be under-estimated by half.) In the US, where the American Petroleum Institute acknowledged the problem of "dissolved organics" in produced water, such as the carcinogens benzene, toluene and xylene (American Petroleum Institute. 1995. op. cit.), the EPA had specified in 1993 that technology used to clean up produced water must also remove aromatic hydrocarbons as far as possible. According to the E&P; Forum (E&P; Forum. 1994. North Sea Produced Water: Fate and Effects in the Marine Environment. Report No. 2.62/204. E&P; Forum, London), North Sea produced water prior to 1994 typically contained aromatic hydrocarbons in the following concentrations:

Table 11: Aromatic Hydrocarbons in North Sea Produced Water, pre-1994

Several times in this study, Greenpeace highlights apparent contradictions between official figures and independent research results. For example:

It is often stated that impacts of production waters in the marine environment are negligible due to the dilution factors. A recent report by the UK Offshore Operators' Association (UKOOA, 1994) stated that "no detectable environmental impacts have arisen from this practice [disposal of produced water], because the minute amounts of oil are rapidly dispersed and biodegraded". However, research is increasingly showing significant environmental effects of such discharges. Planktonic larvae can be adversely affected by produced water plumes, even from discharges in high energy, open coast environments (Raimondi & Schmitt. 1992. op. cit.)... Osenburg's results... also suggest that important biological effects can occur over large spatial scales, despite the discharge into a high energy environment.

With the move to inshore exploration and production in increasingly shallow water [around the UK] the potential effects of produced water need to be fully assessed.
[emphases added. JWGW]

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