"Economic Development and the Environment"
on the Sakhalin Offshore Oil and Gas Fields II

Copyright (C) 1999 by Slavic Research Center, Hokkaido University.
All rights reserved

Oil and Gas Development on the Sakhalin Island Shelf: An Assessment of Changes in the Okhotsk Sea Ecosystem

Alexander Leonov

Ecological Requirements and Standards for Waste Disposal
Requirements and standards on discharges from marine drill devices, accepted in many countries and in the frameworks of international agreements, determine the maximum permissible concentrations of certain polluting substances in the total volume of waste. We present one example of these standards (accepted in the USA and Canada for 1987) where norms and limits on pollution during the investigation and exploitation of marine oil and gas deposits are shown [11]:
  1. drill output
  2. - 1100 tons per well during exploratory drilling; stricter requirements during operational drilling;
  3. drill solutions
  4. - 900 tons per well during exploratory drilling; 25% less for the drilling of commercial wells;
  5. cooling, drainage and ballast waters
  6. - should be water- and-oil separated;
  7. layer waters
  8. - should be water-and-oil separated with mean concentrations of oil hydrocarbons at 48 mg/l and a maximum concentration per day of 72 mg/l;
  9. releases from corrosion protection systems
  10. - releases of small amounts of some metals (aluminum, copper, mercury, indium, tin, zinc) are allowed;
  11. domestic disposals
  12. - should be treated (primary stage of purification).
Methodologies for Controlling the Consequences of Oil and Gas Extraction from a Marine Shelf
There are at least three different approaches to the controlling of the consequences of oil pollution in marine environments. One applies probability methods, one conducts experimental studies, and one performs numerical calculations by using mathematical models.
Probability methods for quantitative assessments of ecological risk
In the last 10-15 years, probability methods for quantitative assessments of ecological risk have been used for controlling the consequences of oil and gas extraction from a marine shelf. This approach is especially used for maintaining ecological safety in conditions of extreme risk. Using similar methodologies, ecological safety problems in risky or extreme situations (for example, emergency oil disposals from wells, breaks in pipelines and other similar accidents) are studied. At the same time, several approaches are used in the application of this methodology for a risk assessment of the consequences of environmental problems in regions where oil and gas deposit development are occurring [68].
In any case, at the first stage, this methodology analyses the opportunities for risk arising. It examines the dangers at different stages of the extraction and transportation processes (disposal of drill wastes, accidents, etc.), and assesses the possible consequences (the degree, character and scale of pollution, biological impacts etc.) and the frequency of the effects (the recurrence of accidents, the dynamics of ecological pollution, etc.).
Experimental studies on the influence of oil pollution on biota
One direction in studies on the influence of oil pollution on aquatic life is connected with the application of experimental system models [69-72]. Some experimental results may be useful for practical purposes in the framework of the Sakhalin Projects:
- Annual experimental studies of the transformations of oil hydrocarbons (mainly paraffins with large amounts of long chain n-alkanes in the C20-C35 range) in sediments of a mangrove estuary showed that at first, the decrease in their concentration was determined by physical processes, and then, by biodegradation. Nitrogen deficiency was the main critical factor in limiting the biodegradation rate [73].
- It was determined that at constant low temperatures, the processes of evaporation and weathering were most important in the transformation and spatial distribution of oil products [74].
- Experiments in the Kara Sea showed that only 1% of paraffin hydrocarbon fractions were mineralized per day by microorganisms. The oil-oxidizing activity of microorganisms was developed for about a month after an oil spill in the northern regions. In Arctic waters, the contribution of microorganisms in the self-cleaning of marine waters from oil pollution was about 5% [67].
- In experiments with oil spilled on ice, oil degradation was practically absent because after nine months only a 5% loss in oil mass was registered [67].
- Experiments were conducted to measure the visibility of oil slicks [75], oil photo-oxidation [76], oil biodegradation [77], the stability of oil emulsions [78] and oil dispersants [79], and the ability of marine microorganisms to produce bio-dispersants to degrade crude oil [80].
Numerical modeling and forecasting
Another direction of studies is connected to numerical modeling and forecasting hydrocarbon distributions in a marine environment. These studies combine the scientific disciplines of applied oceanography and marine ecology.
Many models describing various scenarios for the movement and dispersion of oil pollution have been developed in many countries. They consider the possible consequences of oil spills and are sometimes helpful in preventing and cleaning up oil pollution [9, 23, 81-85]. Models that take into account the mechanisms of oil hydrocarbon transformations in an aquatic environment have also been developed [86].
Experience in the application of these models shows that their efficiency in the prevention and clean-up of oil spills is finely defined by the availability of the necessary data. This data should include the oil's characteristics (oil type, its properties, volume and rate of spillage), and environmental parameters (the speed and direction of wind and currents, depth, temperature, etc.). Unfortunately, the required information is seldom available and in the necessary quantities [84, 85]. The creation of data banks for regions where emergencies are especially probable will doubtless increase the model's reliability and effect on forecasting assessments.
See Figure 5 for an example of this model which looks at the Sea of Okhotsk [87]. This model will allow us to comprehensively evaluate the state of the Okhotsk Sea ecosystem and to add available information about the variability of major parameters: biogenic compound concentrations, bio-masses of micro-organism communities and the parameters of their productivity in different marine basins.
Evaluations and forecasts made within the framework of the Shtokman condensed gas deposit in the Barents Sea [31] are especially interesting. One study considers the possibility of a mixture of gas, condensed gas and layer water in volumes of 8 to 38 million m3/day, and a large-scale spill of condensed gas of 10,000 to 100,000 cubic meters from an opened well for a month. The calculations of the drift and dispersion of oil after such spills during various weather and ocean conditions in the Barents Sea showed a possibility of hydrocarbons moving tens or hundreds of kilometers from their place of origin with a real risk of destroying (or damaging) marine organisms in an area up to 1400 square kilometers. This means that if a similar accident were to occur in the Okhotsk Sea, practically the entire area (the sea is about 1590 square kilometers) may become polluted and that a real risk of destruction will exist for a greater part of its biological marine resources. It is also possible to assume that the system of water currents in the coastal zone of Sakhalin Island [88] will transfer polluting components in a southern or southeastern direction. Thus, there is a great probability that pollution will reach the coast of Japan.
International experience shows that the development of oil and gas fields in the seas and oceans inevitably results in complex ecological problems connected with pollution of the marine environment and the destruction of biological resources. Obviously, the extension of large-scale oil and gas extraction from marine deposits (especially in the Arctic and the Far East Region) is not desirable for the preservation of biological marine resources.
Regular hydrochemical and biological observations should be started to control the state of the marine environment in areas of oil and gas extraction on the Sakhalin Island Shelf.
Numerical models should be developed to simulate the different types of disasters caused by oil and gas extraction in the environment near Sakhalin Island, in particular, to predict the distribution of spilled oil in the short and long term.