Status of oil and gas prospecting works on the Russian Western Arctic shelf Печать

MNATSAKANIAN O.S., TANYGIN I.A., BORISOV A.V.
FSUE AMNGR, Russia

1. Purposive prospecting and exploration works on the Western Arctic shelf began in 1981. Before that, conceptions of the geological structure region and its oil and gas potential had been based on the geophysical studies data, mainly, seismic survey, geological survey and a sparse net of parametric, structural and prospecting wells, located on the Islands of Franz Josef, Kolguev and Spitsbergen Land.
In l981-1982, the first two offshore wells were drilled the Pechora Sea in the Dresvianskaya area. The drilling was experimental and performed from the offshore signed off vessel "Sevastopol", updated into a fixed platform.

2. Planned prospecting works began in 1982, when the first specialized drilling ships "Valentin Shashin" and "Victor Muravlenko", and later, the semisubmersible and jack-up drilling rigs joined "Arktikmorneftegazrazvedka". Within the period of 1982-2003, 28 structures had been put into drilling, 57 wells had been spudded, 48 wells had been completed by drilling, 37 wells had been tested, in 32 of which commercial oil and gas influxes were gained. Five wells were not drilled to the target depths and were conserved in the process of drilling due to the state financing cessation. The offshore prospecting and exploration drilling scope as of early 2004 has amounted to 155 thousand meters.

3. The main result of the performed oil and gas prospecting works is a discovery of the Russian new large hydrocarbon base, comparable, by its general potential, with well known provinces of the Western Siberia. Eastern Siberia and European North.

Commercial oil and gas presence of the section has been proved in a wide stratigraphical range : in the Barents Sea - these are Trias and Jura deposits, in the Pechora Sea these are Low Devonian. Carboniferous, Low Permian. Upper Permian and Triassic deposits, in the Kara Sea these are Cretacious rocks. Besides, intensive oil and gas shows have been noted in the Cretacious deposits of the Barents Sea and in the Silurian deposits of the Pechora Sea.

Initial summarized resources of the Western Arctic Seas amount to 66.8% of the total resources of the Russian shelf, including gas -76,2% and oil-37,7%.

The perspective land area ( without a disputable area) of the Barents Sea amounts to 726.5 thousand km2, the Pechora Sea -132.3 thousand km2, the Kara Sea -482 thousand km2.

4. 15 oil, oil and gas, gas and gas- condensate fields were discovered, including 4 oil fields, one oil and gas field and 10 gas and gas- condensate fields. By volume of C1+C2 categories resources, three fields refer to the unique ones (Shtockmanovskoye, Leningradskoye and Rusanovskoye gas- condensate fields), and 8 fields refer to the large ones (Prirazlomnoye, Medyn-more, Dolginskoye oil fields, Ludlovskoye, Ledovoye and Murmanskoye. Kamenomysskoye, Severo-Kamenomysskoye gas and gas-condensate fields). High efficiency of exploration works has been gained, all fields have been discovered by the first wells, more rare - by the second wells, drilled on the prospecting areas.

5. In spite of the twenty-three-year period of purposive oil and gas perspective works, the extent of the regional study is still too low. In the Barents Sea, one drilled well is per 26,9 thousand km2, in the Pechora Sea - per 8.8 thousand km2 and in the Kara Sea - per 80.3 thousand per km". Frequency of the seismic observations for the perspective lands main part is characterized by values from <0.1 to 0.1-0,25 miming km per km", which is several orders lower, than the adjacent countries shelf extent of study (the Norwegian and North Seas). Geological structure of the Barents and Kara Seas northern parts is noted by only sparse seismic profiles, there is not any drilled well here.
From 15 discovered fields only two fields are ready for development -Shtockmanovskoye and Prirazlomnoye fields, the production from which is planned to start in 2010 and 2006, accordingly.

6. In the light of modern concepts, the main perspective of oil presence are comiected with the Pechora Sea shelf, while the Barents and Kara Seas shelf is considered, mainly, as a gas presence one, although the possibility of oil fields discovery is also expected here, in the first turn, in the northern parts of these seas.

As for the occurrence depths and sea depths, modem drilling rigs are capable to develop unexplored resources.
hi the Barents Sea. 83 % of unexplored hydrocarbon resources (category Сз+Д) are predicted in the depth range of up to 3 km, 13%- in the range of 3-5 km and. only 4%- lower than the depth of 5 km; in the Pechora Sea these indices amount to 39%, 42% and 19%, in the Kara Sea-72%, 26% and 2%. In the Barents Sea 75%. in the Pechora Sea 95% and in the Kara Sea 97% of the hydrocarbons are predicted at the sea depths up to 200m.

At the same time, hydrometeorological conditions cause critical limitations for exploration works. Except for the south-western part of the Barents Sea, being free of ice all-the-year-round, all the rest water part refers to an ice class. The most severe ice conditions are observed in the Kara Sea, where an ice free period is limited to 2-3 months, as well as in the Pechora Sea, where this period amounts to 4 months, as an average.

7.Development of the Western Arctic shelf oil and gas potential, including preparation of new commercial reserves and oil and gas production from the discovered fields, is to be considered as one of the paramount trends for the Russian oil and gas fuel and energy complex development. Just this trend, in spite of severe environmental conditions of the shelf development- is capable, by its potential, to smooth over oil and gas production decline in the Russian continental part, expected in the nearest future.

8.When prospecting new fields, it is necessary to note that exploration works are to be performed in poorly studied and undeveloped regions. While conducting such works, the risk will be extremely high. To reduce the risks and increase investment attractiveness, it is required to work up, in the first turn, with regard to parametric drilling volumes increase, and consequently, to implement the program of subsoil regional study, included in "General State Strategy for Study and Development of the Russian Continental Shelf Oil and Gas Potential." Geologically, parametric drilling in the near future is reasonable to be performed on Pakhtusovskaya, Vernadskaya (the Barents Sea) and Russkaya (the Pechora Sea) structures.

9.Financing of works related to the subsoil regional study and drilling of the first prospecting and appraisal wells of the licensed sites with discussion potential, being tendered, are to be performed for the account of the federal budget funds, which will allow to estimate an actual price of such sites, and as a result, to increase income into the budget from their sale.

10. For the parametric drilling perspective plan for the period up to 2020, it is also required to include drilling of a parametric well in the disputable zone ( Central Arch) and propose the Norwegian companies to participate in this project.

ARCTIC SHELF OIL AND GAS CONFERENCE 2004