STOUPAKOVA A.V.
Geological faculty, Lomonosov Moscow State University, Russia

Replenishment of the hydrocarbons’ resources base shall be feasible only by expanding oil-and-gas prospecting and exploration activities into the new regions, where significant increment of the resources takes place at the initial phases of their development and is due to discoveries of unique and giant oil and gas fields.

Offshore areas of the Russian Continental Shelf have high HC potential; their initial recoverable resources are estimated at 136 bln. tons of oil equivalent, thus corresponding to 25% of the total world HC resources (Trutnev, 2005). Main portion of HC resources on the RCS is located in the remote and capital-consuming Arctic offshore areas. This determines high importance of optimized structural model in order to understand oil-and-gas bearing capacity generation in the Arctic offshore basins and to justify new fields prospecting efficiency. This requires not only additional data, but also joint reassessment of the material available on the basis of new scientific achievements of the fundamental science – geology, which aims at predicting the structure and oil-and-gas bearing capacity of the potential productive zones.

History of the unique HC fields’ discoveries. Exploration of the Arctic shelf has its own long history. Most explored shelf areas are in the Barents and Kara Seas. In the Russian sector of the Barents Sea exploration works started in 1970-th, when in 1969 the first assessment of oil-and-gas prognostic resources was performed and conclusions were made on the high potential of the Russian Arctic Shelf (Nikitin B.A., Rovnin L.I., 1996). Approximately at the same time exploration activities started in the Norwegian sector of the Barents Sea. During 1970-th the Norwegian geological agencies performed regional seismic works, and in 1980-th active drilling was conducted on the Barents Sea shelf.

1980-th – is the period of the most intense exploration activities both in Russian and Norwegian sectors of the Barents Sea.

First discovery was made in 1981 by Norwegian geologists using wells 7120/8 and 7120/12-2 drilled at Alke and Askelad structures, located in the central part of the Hammerfest Trough. Obtained gas flow has confirmed the first Barents Sea gas field – Askelad, which later was used for the first pilot production. Currently Askelad field is part of the large gas field – Snohvit.

At the same time first wells in the Pechora River estuary were drilled, and in 1983 Russian geological agencies discovered Murmanskoye and Severo-Kildinskoye gas fields. In 1988-1989 unique gas-condensate fields were discovered – Rusanovskoye in the Kara Sea and Shtokmanovskoye in the Barents Sea. Their discovery was of the principal significance and has dramatically changed the attitude to the Western Arctic Shelf. Further works have confirmed high potential of these offshore areas through the discoveries of other gas fields in the Barents and Kara Seas, and of oil fields offshore Pechora Sea. Since 2001 Gazprom’s subsidiary “Gazflot” actively works in Ob-Taz Gulf – the northern extension of Western Siberia basin, where several unique oil-and-gas fields have been already discovered.

Arctic basins structure and generation of their oil-and-gas bearing capacity. All sedimentary basins of the Arctic shelf with ascertained and potential oil-and-gas bearing capacity are located on the continental’s type crust and are attributed to deep troughs, where thickness of the sediments attains 15 km and more. Such troughs include Barentsevomorsky,Yuzhno-Karsky, Laptevomorsky, Vostochno-Sibirsky, and Severo-Chukotsky ones. Consolidated crust in their deep parts has thickness of 10-15 km, and the depth of the Earth crust bedrock (Moho discontinuity) varies from 40-42 km at the flanks to 33-35 km (sometimes to 25 km) in the axial dipping zones. Regional rifting zones happened to be the tectonic elements, which have determined epicenters of the dipping sedimentary basins and relevant distribution of the large zones of oil-and-gas accumulation. Most favorable conditions for unique HC reservoirs were developed within their limits.

Modern research techniques allow simulating of oil-and-gas generating processes in the section of the sedimentary sheath for individual structural zones of the basin. Simulation indicates existence or absence of oil-and-gas generating processes and their dynamics in time and space. Simultaneously the scale and direction of oil-and-gas generating processes can be determined both within structural-lithological complexes (oil-and-gas bearing ones) and between them.

The process of the basin’s oil-and-gas bearing capacity generating starts well before its modern structural plan development, and is associated mainly with the zones of the ancient basins’ active dipping. Tectonic processes in the basin and its involvement into new dipping promote universal development of oil-and-gas generating processes both in the ancient stratums and in the younger ones, formed during subsequent stages of the region development. The basin’s inversion leads to fluid migration processes’ activation, reshaping of the main oil-and-gas generating zones, HC systems blending, and forming of large HC accumulations. Potential risks exist in the zones, being subjected to strong tectonic faulting, which could have led to destruction of the previously formed reservoirs.

Personnel training. The task of personnel training for prospecting and exploration works in the Arctic is not less challenging than the integrated surveys, aimed for the development of the northern offshore areas. Personnel training shall comply with the goals of production and research organizations, be up-to-date, and shall be based upon particular R&D projects. In this aspect the cooperation between universities and state-owned companies becomes very important. It can cover educational and joint innovation projects with participation of new specializations and research areas in new technologies, environment protection, and efficiency of exploration works on the Arctic shelf. Research-and-development activities of the scientific groups in the applied institutes, academic structures, and universities are directly linked to current challenges of the mineral resources’ base expansion and development of the new poorly explored regions. Joint activities in the education and science allow to use the international expertise in the Arctic offshore exploration and to make comparisons of all the Arctic basins’ geological structures.

Integrated approach to the Arctic shelf exploration and development will be mutually beneficial and will assist both new generations’ personnel training under direct interaction between classic educational school and oil-and-gas business, and solutions of specific research and production tasks. Participation of the leading companies in supporting and upgrading current and future R&D and educational programs will allow finding solutions for challenging exploration activities both onshore and offshore in order to replenish the mineral resources base.

Oil and gas of Arctic shelf 2008