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Khalimov, E. (Institute of Geology and Exploration of Combustible Fuels, Moscow) | Orudgeva, D. (Institute of Geology and Exploration of Combustible Fuels, Moscow) | Obukhov, A. (Institute of Geology and Exploration of Combustible Fuels, Moscow) | Lovelock, E. R. (Shell Internationale Petroleum Maatschappij, Netherlands)
Abstract. Russian sea shelves cover about 3.9 million sq. km (14% of total world area). The petroleum potential of the Russian shelves exceeds the hydrocarbon (HC) reserves of the North Sea more than tenfold. However, 82% of the HC resources of the Russian shelf are confined to the Arctic seas with an extremely severe environment (low temperatures, ice, high waves, storms and hurricanes, etc.). About 14% of the undiscovered resources lie in the Far East and 4%-in the Russian sectors of the Baltic and Caspian seas. Russian offshore HC resources are poorly developed. Oil reserves to resources ratio is about 1% in the Arctic seas and about 13% in the Far East seas. 30 oil and gas fields have been discovered and quite a few promising structures identified in the Russian sea shelves. Geologic structure and development conditions of the following fields are given in brief: Peschano-Ozerskoye (1982), Gulyayevskoye North (1986), Prirazlomnoye (1989) (the Barents Sea); Odoptu Offshore (1977), Chaivo Offshore (1979), Lunskoye Offshore (1984), Piltun-Astokhskoye (1986), Arkutun-Daginskoye (1989) (the Sea of Okhotsk). Oil discoveries are classified according to their commercial importance and development conditions. Oil production volume from new Russian offshore discoveries is forecasted. The importance of world experience, application of advanced technologies and up-to-date equipment for offshore oil exploration, production and drilling in Russia is evaluated. INTRODUCTION The total area of the offshore provinces of Russia including both the outer seas (Arctic and Far East) and the inner seas (Caspian, Baltic, Rlack Seas and Sea of Azov) amounts to nearly four million km2, or 14% of the world's shallow water offshore regions. The water depth at the edge of the shelves reaches 240 m while the width varies greatly from 5 up to 1350 km. Numerous depositional basins are to be found within this vast offshore area, of which the largest are as follows: - East Barents, South Kara, Laptev, East Siberian and Chukchi in the Arctic - Anadyr, Navarin, Khatyrka, Olyutorsk-Komandor, North Sakhalin, Okhotsk-Kamchatka and South Okhotsk in the Far East The oil and gas potential of Russia's offshore provinces is 6 times larger than that of the North Sea. However, 82% of its resources are located within the Arctic Seas which feature the most harsh climatic conditions (i.e. low temperatures, thick sea ice for most of the year, high waves and storm force winds etc.). The Far Eastern seas account for 14% of the potential resources while 4% is to be found in the Baltic, Caspian, Black Sea and Azov provinces. Most of the hydrocarbons remain undiscovered. So far only about 1% of the potential reserves in the A
Abstract. The petroleum system is becoming accepted as a unifying concept in which various research focused at finding new hydrocarbon reserves can be conducted more efficiently. Proposed definitions of the petroleum system vary, however, the system is basically understood as a group of discovered and/or undiscovered genetically related hydrocarbon accumulations that emanated from a contiguous body of source rocks and that occupy a specific rock volume. The petroleum system map, which shows source rocks and the genetically related accumulations and cross sections which show the stratigraphic position of the accumulations, clearly demonstrate the explorationist's interpretation of the origin and migration route of hydrocarbons. Three petroleum systems are compared to more graphically demonstrate how the concept is used in exploration, research and resource appraisal. The systems, from most to least explored, occur in northern China in the Jizhong subbasin, in northern Alaska in the Colville basin, and in the Bering sea in the Anadyr basin. Even though the amount of information varies for each basin, the petroleum system can be meaningfully portrayed. The exploration geologist can use the petroleum system map and cross sections to develop plays to find undiscovered commercial quantities of hydrocarbons within the system, or the system map and cross sections can be used as an analog for another area which contains a little explored system. The research geologist can investigate and model how a system works, either in total or in part, which helps in locating new plays and in decreasing exploration risk. The appraisal geologist can evaluate the petroleum system map from a historical view to study discovery rate process or compare similar systems that have different levels of exploration to determine the ultimate yield of the little explored system. 1. INTRODUCTION A conceptual understanding of a petroleum system as a set of oil and/or gas fields occurring in a specific geologic setting and relating to a particular mature source rock is intuitively familiar to most geologists; nevertheless, several attempts have been made to formalize the term in order to make it more applicable to petroleum geology, research and exploration. Without formally defining the term, Dow (1974) was first to introduce and use ‘oil system’ to explain the relation of mature source rock to oil accumulations. Perrodon (1983) used the term petroleum system, and later Perrodon and Masse (1984) defined the petroleum system as an organized set of geological events in space and in time that results in the formation of a petroleum province. In Meissner et al. (1984), a hydrocarbon machine (or petroleum system) is a rock seq
ABSTRACT A description of ice conditions in the Bering Sea an~ their influence on navigation are given on the base of multi-year observations in this region. The ice drift is one of the main factors and it changeability is important considering a rapid development of North Pacific Region. INTRODUCTION The winter navigation in the Bering Sea is very difficult. It is caused by Aleuth depression in the south part of sea characterized by storm winds with velocities above 40 m/s and continuous durability up to 10 days. In the north part the navigation conditions are influenced by ice cover. The first ice in the Bering Sea appears usually in mid-October in Anadyr Bay, Krest Gulf and western part of the Bering Strait. Then the ice appears in in the following order of Gulfs: Anadyr, Norton, Karagin, Olyutor and Bristol. Quite in November the ice of Anadyr and Norton Gulfs usually connects into solid massive. In severe Autumns the ice creation begins in mid-September and in warm seasons the first ice appears on 1.5 months later. ICE COVER CHANGEABILITY An ice cover are slowly increased up to the end of November during every winter. Then in December it increases rapidly with following slowdown. At the beginning period of creation the ice extend to latitude direction. From December the ice cover takes form of wedge with tip directed to Bering Gulf and then to Navarin Cape to west. Non-simultaneous appearance of maximum ice cover are at the different winters. The small cover winter have a maximum at the end of February with 20% of sea area equals to 2,315,000 km. For other winters a maximum take place at the first halh of April with 38% to 56%.
ABSTRACT The Bering Shelf is a large shallow water shelf situated south of the Bering Strait, north of the Aleutian Islands and west of Alaska. The shelf contains four large Tertiary basins. The two largest basins, the Navarin and the St. George, are products of the Neutralization of an old North Pacific Oceanic plate. Near the beginning of Tertiary time the Kula plate ruptured near the present Aleutian Arc. The plate fragment on the northern side of the rupture was cut-off from its spreading center and Neutralized. The old Mesozoic subduction zone was transformed from compression to tension as the subducting downmoving tip broke away from the Neutralized fragment and continued downward. The result of the breakaway along the length of the old plate interface created two very large extensional basins. Together they are approximately 750 miles long, average over 100 miles in width, and are in excess of 30,000 feet deep. The obvious analog is the Gulf Coast Interior Salt Basins. INTRODUCTION The Bering Shelf is the largest drillable shallow marine area in the free world. It is essentially situated between the eastern-most arctic tip of Siberia and western Alaska (Figure 1). The Soviet Union has previously established production in the Gulf of Anadyr and are involved in exploration on their portion of the Bering Shelf. This summer a consortium of freeworld oil companies drilled a deep "C.O.S. T." well (stratigraphic test) in the St. George basin on the U.S. portion of the Bering Shelf. Since the Bering Shelf is divided between the United States of America and the Soviet Union (90% on the U.S. side), the political problems spurred by a deepening world energy crisis are obvious. Unfortunately, despite a flawless drilling record in the "C.O.S. T." well, the promised lease sale in the St. George basin has been postponed. GEOLOGY The Bering Shelf extends nearly 400 miles west of the present Alaskan mainland. The edge of present continental shelf follows the old Mesozoic shelfedge. Despite this approximation, the geographical implications are not valid. The Aleutian Arc was not present and the deep indention (Siberia to Alaska) was probably much straighter. After all, the continent of North America broke away from Africa and Europe and drifted 3,000 km northwestward during the Mesozoic and the Lomonosov Ridge in the Arctic Ocean drifted nearly 600 km in the Tertiary. It is important to realize the geographic disparity when considering plate interactions. If two plates collide at angle, it is probable that the interface will be in the form of a transform fault such as the San Andreas fault in California. The pla1e interface between the North Pacific Oceanic plate (Kula) and the North American plate was a subduction zone.
In his introduction, the CHAIRMAN, Mr J. D. DEWHURST, said the five papers in this Panel cover an area from the North East USSR in the north to Australia in the south, from India in the west to the Pacific Ocean in the east. Unfortunately a paper dealing with the Peoples Republic of China has not been forthcoming, leaving an important gap in the coverage. The area is one in which the earliest discoveries of oil were made but where much exploration still remains to be done. Part of the area is covered by two large oceans so that much of the exploration remaining is offshore, while nearly every kind and certainly every phase of exploration play is represented and there are signs that in future the trend will be quite rapidly towards the development of more and more sophisticated plays. Above all, the area embraces what might be regarded as a tectonic crucible in global terms and the effects of these complicated tectonics is critical to our subject. The largely theoretical considerations covered by Panels 1-4 find expression and practical relevance in exploration in the Far East. In presenting the paper "Sedimentary Basins of the Far East, and North East of the USSR and their Possible Oil and Gas Content", Dr JU BURLIN drew attention to the large number of prospective basins present in the area. A number have given oil and gas indications and some production but only the East Sakhalin Okhost Basin has significant producing fields. The main prospect zones in the area are the Upper Cretaceous and Neogene clastics, which in some basins are terrigenous in origin, and particular emphasis has been placed on the nature and degree of maturation of source materials in the various basins, which can determine whether oil andlor gas will be generated. Exploration in the area is, in general, in an early stage and many of the basins giving encouraging indications extend offshore. In reply to a question by Mr S. E. CHURCHFIELD concerning source rocks in the Anadyr Basin mentioned in the paper, Dr BURLIN confirmed that the Upper Cretaceous was considered likely to be a source rock for gas because of the exclusive humic content of the organic material, whereas the overlying rocks had a significant sapropelic content and hence were suitable source rocks for oil. Dr BURLIN said that the possible reserves of oil and gas likely to be discovered in the area had not been quantified but he considered that they could be very big, possibly more than 1 billion tons, in some basins. Mr H. M. LIAN asked Dr JU BURLIN to comment on the relationship between the oil and gas fields of Western Alaska and those of North East Siberia. Dr JU BURLIN replied that the question of the relationship between Alaska and Northern Siberia is connected with the existence of transform line