"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

The vast amount of oil and gas deposits on the Sakhalin Island Shelf has been surveyed intensively over the last twenty years. Many large companies (Marathon, Shell, Exxon, Sodeco and others) have already completed preliminary plans on oil and gas production on the eastern and north-eastern sites of the Sakhalin Island Shelf within the framework of the Sakhalin-1 and Sakhalin-2 projects. The stocks of just one of the five surveyed deposits (Odoptinskii) amount to more than 200 million tons of oil and 1011 cubic meters of gas [1]. The total amount of oil and gas on the north-eastern shelf of Sakhalin Island is 1.2 billions ton and 800 billion cubic meters respectively [2].
Under the proposed Sakhalin-1 project, Sakhalin Island will become a large oil and gas extracting center and supplier to the Far East and abroad. 65 prospecting wells have been drilled on the Sakhalin Island Shelf [3]. The project calls for the construction of six drilling platforms (one self-elevating), the drilling of more than 600 wells (up to 3000 meters deep) producing more than 60,000 tons of oil and 80 million cubic meters of gas per day, the laying of a system of underwater pipelines (with a diameter of up to 720 mm), the building of large shore facilities, and the removal of up to 70,000 cubic meters of the seabed [4].
This paper will analyze the impact of the modern marine oil and gas industry on a marine environment and fisheries in marine shelf and oceanic zones. The extraction of oil and gas in a marine environment has been a sector of the global economy for the last 20 years. This paper will examine the negative impact of this industry on marine ecosystems and biological resources. It will determine the degree of damage caused by water pollution and changes in fishery conditions in regions where oil and gas extraction has occurred. It will formulate the steps necessary for preserving the environment in regions of oil and gas extraction.
The Environmental Effects of Marine Shelf Oil and Gas Extraction
There are many examples of humanity's negative impact on water ecosystems, such as the discharge of industrial wastes, the washout from fertilizers, toxic chemical dumping, the damming of rivers, and unsustainable water consumption. The large-scale development of marine shelf oil and gas deposits has also had a negative impact. The technology for oil and gas recovery used in Russia for land-based continental deposits is combined with ecological risk owing to significant losses of extracted raw materials.
The most widespread and dangerous consequence of marine oil and gas (as well as any other) industry is pollution of the environment [5]. Pollution is associated with all kinds of activities at all stages of a deposit's development. Globally, the oil and gas industry disposes of more than 3 billion tons of solid wastes, about 500 km3 of sewage and about 1 billion tons of aerosols per year [6, 7]. These releases are composed of more than 800 substances, many of them related to oil and its by-products. Globally, the total annual loss of oil during its production and transport exceeds 45 million tons; 22 million tons are lost on land; about 7 million tons are lost in the sea; and 16 million tons enter into the atmosphere as a result of the incomplete combustion of liquid fuel [7]. The essential part (up to 10 to 20%) of the total volume of marine gas production is burned up in flare systems and gas generators on platforms and is a source of atmospheric pollution.
Practically all stages in the development and production of hydrocarbons are accompanied by discharges of liquid, solid and gaseous waste (Table 1). The typical discharge volumes of the most widespread and hazardous substances are shown in Table 2.
There are four main stages in the development of oil and gas deposits [1]:
  1. geological and geophysical surveys and evaluation of raw material stocks (seismic and drill exploring);
  2. the preparation of a deposit for exploitation (installing stationary platforms, laying pipelines, constructing shore terminals, drilling works, testing wells, etc.);
  3. the deposit's exploitation (extraction, separation and primary processing of hydrocarbons; the sinking and reparation of wells; the transportation of liquid and gaseous products, etc.);
  4. completion and termination (dismantling work; the removal of platforms and pipelines; the preservation of wells, etc.).

Each of these stages is characterized by certain activities and has an influence on the environment (Tables 3 and 4). This influence has a complex character and is seen in the form of the physical, chemical and biological effects in an aquatic environment, the seabed bottom and, partially, in the atmosphere.
The mean time of a deposit's exploitation is 20 to 40 years. However, after only 5 to 10 years, an area may have new petroleum platforms, abandoned drill constructions, different devices for laying underwater pipelines, oil tankers, vessels for seismic investigation, etc. Thus, the local effects are integrated and become regional. Their character and intensity can be distinguished depending on the combination and number of natural and technical factors. For example, in the North Sea, there are around 4000 drill wells (160 are working from stationary platforms), and about 250 underwater terminated wells and more than 5000 km of underwater pipelines [13].
The development of any oil field results in the release of polluting substances into the atmosphere. As for the development of marine deposits, this fact has not attracted special attention so far. However, oil and gas recovery experience on land shows that releases into the atmosphere occur at all stages of development. The most widespread sources of such releases are [1]:
- the continuous or periodic combustion of gas and excessive quantities of hydrocarbons during the testing and operation of wells and the continuous combustion of flares and low pressure ignition devices for gas removal from tanks and pressure regulation systems;
- the combustion of gaseous and liquid fuel in power equipment (gas turbines, internal combustion engines) on platforms, vessels, and shore structures;
- the releases from degasified drill solutions, technological reagents and extracted hydrocarbons used in various operations for production, processing, transportation and storage.
The volumes of annually combusted petroleum gas in Russia amount to 10 to 17 billion cubic meters [14]. Preliminary calculations for Great Britain's marine oil and gas industry have shown that about 10% of produced gas (approximately 46 billion cubic meters) is combusted in flare systems and used for its own oil field power requirements [15]. The total amount of releases resulting from the production of oil and gas in Great Britain's sector of the North Sea are estimated at 20,000 tons annually; the emission of methane is about 75,000 tons annually (or accordingly, less than 0.02 and 0.08% of all atmospheric releases of volatile organic compounds in Great Britain). Similar assessments for marine oil and gas fields on the Norwegian Shelf showed the dominance of carbon dioxide gas (88%) in atmospheric releases as well as nitrogen oxides and volatile organic substances [16].
Deposit waters entering from underground oil and gas bearing structures during the industrial extraction of hydrocarbons account for a large amount of pollution. In some cases, the additional disposal of large volumes of marine water (tens or even hundreds of thousands of tons) is primarily pumped through forced channels to maintain well pressure. These waters are usually polluted by oil, low-molecular hydrocarbons, inorganic salts, technological reagents and suspended substances and should be treated before disposal into the sea. Such treatment in marine conditions, however, is technologically hindered [17].
Data from the 1980s for British oil and gas fields in the North Sea show that 60 to 78% of all usable chemical materials were disposed as wastes into the sea (or annually 117,000 to 138,000 tons) [15].
The volume of drill wastes is usually within 1000 to 5000 cubic meters per each passed well, and their amount is usually measured by tens (for one commercial platform) and many hundreds of thousands of cubic meters (for larger deposits). In the North Sea, 22,000 tons of oil, 100,000 tons of chemical admixtures (inorganic and low toxic), and 4900 tons of potentially dangerous compounds (biocides, corrosion inhibitors, detergents, demulsifiers, oxygen absorbents, etc.) entered the water with drill slime disposals in 1988 [18].
At present, two main types of drill solutions are used - mixtures based on oil and other organic substances (diesel fuel, paraffins and others) or water (fresh or salt with the addition of clay and other components). During the last 10 years, the preference has been given to the least toxic water-based drill solutions. However, in some cases (for example, in the drilling of inclined wells in solid rock) oil-based solutions are used [5].
Accidents remain inevitable events for any oil field. As well, they are a pollution source at all stages of the industrial exploitation of oil and gas deposits (during prospecting drilling, industrial production, and transportation by pipeline and oil tankers). The most prevalent reasons for accidents are: equipment failures, staff errors and extreme natural phenomena (seismic activity, glacial fields, storms, etc.). The ecological consequences of accidents are especially dangerous near the coast, in shallow water or in the areas with slow water exchange [1].
One of the main factors behind ecological risk in marine oil fields is the failure of underwater pipelines. The reasons for their damage can be quite varied (from material defects and pipe corrosion, up to ground erosion, tectonic shifts in the seabed, and effects of ship anchors and bottom trawls). The evaluated mean probability of accidents with underwater pipelines in North America and Western Europe is 0.00093 and 0.00064 respectively, and the main cause for these failures is welding defects [4].
The Russian experience in the development of oil fields in Siberia shows that the oil outflow from pipelines is a common phenomenon: 1 to 2% of the oil extracted in Russia is lost as a result of accidental spills and releases. The amount of these losses (for example, in the Tumen' area in Komi Republic) is estimated in the hundreds and thousands of events, and the volume of oil spilled is estimated in the millions of tons [19, 20]. If this rate of loss is repeated in oil and gas deposit development on the Sakhalin Island Shelf, serious consequences will occur. The construction of a main pipeline is planned along a greater part of the eastern coast of Sakhalin Island and through main rivers where the spawning and the reproduction of unique salmon populations occurs. On the whole, the construction of oil pipelines threatens to pollute rivers and lakes, as well as soils and underground water resources [21].
Despite the increased attention to ecological safety and accident prevention in marine oil fields, emergencies are inevitable. Statistics show that on the American shelf of the Gulf of Mexico, the number of emergency oil spills (in volumes of more than 1000 barrel (one barrel = 134 kg) per billion barrels of oil extracted or displaced averages 0.79 (during drill work on platforms); 1.82 (during oil transportation by pipelines) and 3.87 (during transportation by tankers) [22]. The volume of oil spilled during failures at drill works on the Great Britain Shelf in the period from 1980 to 1988 were between 0.00011 and 0.0029% of the amount of annually extracted oil on similar drill platforms [23].
The probability of accidents occurring on drilling wells is 0.1 to 0.5%, and, during their repair, 1 to 2.5% [24]. In cases of larger oil spills (more than 10,000 tons), emergencies do not exceed 3% [4]. Available studies show that 2.3% of the total number of marine drill platforms experience large failures annually [25]. Oil spills on a surface may be easily noticed and handled. However, about 33% of reported releases from marine wells were in the form of natural gas in the shallow-water areas of a shelf, and about half of these cases were connected with the serious failure and damage of drill installations [26].
The ecological consequences of oil tanker transportation and failure statistics are considered in detail in many publications [9, 27-29]. The probability of tanker accident (more than 10,000 tons of tonnage) is evaluated as 2.3% for each 10 million tons of deadweight. In other data, the specific accident rate of oil tankers with tonnage more than 6000 tons was around 2% at the end of the 1980s [30].
Running aground on coastal reefs, collisions with other ships, and fires and explosions of cargo are often mentioned as the main reasons for tanker accidents and other large oil spills. In 1989, the amount of oil spilled in tanker accidents was 114,000 tons; in 1990, 45,000 tons. The total annual volume of pollution from marine oil transportation is more than 500,000 tons [27].
Many examples are available in literature and statistics on large tanker accidents (about 2% per year) which clearly illustrate the high risk of emergencies during hydrocarbon transportation in the Barents Sea. They also testify about the possible catastrophic consequences of accidents because the damage can exceed all recorded cases. Calculations confirm the validity of this fear: for oil tankers with a tonnage between 5000 to 50,000 tons the area of oil and gas condensate spills could be between 3000 to 50,000 square kilometers; for super-tankers, spills could reach up to 84,000 square kilometers [31]. This would have a devastating effect on fisheries.
An examination of large tanker accidents, covered in detail in literature, begins with the Torrey Canyon tanker accident near the English Channel in 1967, when a spill of 95,000 tons of oil polluted the Atlantic coast of France and England with many consequences to the environment and fisheries. Many other accidents, such as the Amoco Cadiz (1978, 220,000 tons of oil), the Exxon Valdez (1989, 40,000 tons of oil), the Braer (1993, 85,000 tons of oil) have followed. Each of these accidents had its own causes, but in all cases the level of petroleum pollution reached lethal or threshold concentrations for marine fauna (especially for birds and mammals), with consequences far beyond ecological damage to the sea and the coast [1].
Regarding the scale and burden of the consequences that followed after the Exxon Valdez, the costs of the clean-up were 2 billion dollars; compensation for the environmental damage and to the local population was above 3.5 billion dollars. About 15 billion dollars should be added to these costs for judicial procedures [32].
Other dangerous situations can arise with gas-carrier ships, which are used alongside with oil tankers for the transportation of liquefied natural gas. Such accidents are less probable in comparison with oil tanker spills, but they threaten the destruction of all forms of life in an area up to 400 square kilometers [29]. Of seven gas carrier ship accidents (recorded until 1980) transporting liquefied natural gas, three cases were caused by explosions.
An accident with a ship transporting methanol (a toxic substance completely dissolvable in water) may lead to an ecological tragedy. Calculations have shown that an accident involving a similar ship with a tonnage of 35,000 tons, for example, in a coastal zone in the western part of the Murmansk area would destroy thousands of square kilometers of fisheries [31].