U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY
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The Timan-Pechora Basin Province of Northwest Arctic Russia: Domanik – Paleozoic Total Petroleum System by |
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and Kulibakina, 1997). Both the upper member of the Lower Triassic Charkabozh
Formation and offshore marine shales of Upper Jurassic to Lower Cretaceous
age also are regional seals to several hundred meters in thickness (Oknova,
1993). ASSESSMENT UNITS 
The Domanik-Paleozoic total petroleum system is somewhat smaller than the Timan-Pechora Basin geologic province (Figure 5), with 18.8% of the province excluded (84,000 sq km – all northern offshore waters). Three assessment units are designated to assess resource potential – N.W. Izhma-Pechora (#10080101), Main Basin Platform (#10080102), and Foredeep Basins (#10080103). For the purposes of this resource assessment, no field-growth function will be utilized for data from this province because of some known cases of over-reporting of reserves (G.F. Ulmishek, personal communication). N.W. Izhma-Pechora Assessment Unit #10080101
The northwestern portion of the Izhma-Pechora Depression (Figure 1 and Figure 5) is a hypothetical assessment unit. It has no known fields and is outside of the known area of active source rock. N.W. Izhma-Pechora comprises 19.5% of the total petroleum system and is approximately 70,600 sq km in size, with 10.5% of that area offshore. Seventy-five onshore wells have tested its area. Risks are increased relative to the Main Basin Platform (discussed below) for source rock presence, migrationroutes, and the timing of trap formation relative to migration. Main Basin Platform Assessment
Unit #10080102 |
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the following Foredeep Basins (#10080103) assessment unit because of differences in burial history, trap types, and timing of trap formation as related to generation and migration/remigration (Figure 6).Most significant structures onshore have been tested, but offshore areas are largely unexplored. A greater emphasis on stratigraphic traps – alone or in combination with structural enhancement – is expected for future field development and reserve additions, especially for the onshore areas. The following major trap types are discussed in Ulmishek (1982) and Dedeev and others (1994). Lower Paleozoic carbonate and siliciclastic rocks generally have an angular configuration, updip to the west, beneath the regional pre-Middle Devonian unconformity. Overlying Middle Devonian sandstones are eroded by the post-Middle Devonian unconformity and preserved in SSW-NNE trends that weave across this assessment unit (Figure 55 in Ulmishek, 1982). Similarly, Upper Devonian to Tournaisian and Lower Permian carbonate build-ups have delineated shelf-edge trends (Figure 56 in Ulmishek, 1982; Figure 1 in Rostovshchikov and others, 1991; Figure 1 in Belyayeva, 1992; Figure 4 in Belyakov, 1994; Figure 2 in Zhemchugova and Schamel, 1994; Figure 1 in Aleksin and others, 1995 ; and Figure 1 in Ivanova, 1997). Finally, Permo-Triassic stratigraphic and combination traps are both known and further expected. Foredeep Basins Assessment Unit #10080103
The Foredeep Basin assessment unit is also established with production and comprises 24% of the total petroleum system. It is approximately 87,100 sq km in size, with 8.7% of that area offshore. Trap styles in this assessment unit will be dominated by Uralian and Pay Khoy thrusted closures without surface expression, and sour gas is expected to constitute a large portion of the resource base. Not included in this assessment process are unconventional gas accumulations (Ben Law, U.S. Geological Survey, personal communication) in Artinskian and Kungurian coaly siliciclastics of the foredeep region. |
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