4th EAGE St.Petersburg International Conference and Exhibition on Geosciences - New Discoveries through Integration of Geosciences

The petroleum resource assessment of the Yenisey-Khatanga Basin exemplifies the United States Geological Survey assessment process for basins in the Arctic. This assessment of crude oil, natural gas, and natural gas liquids (collectively referred to as petroleum) resources is one of several conducted by the U.S. Geological Survey Circum-Arctic Oil and Gas Resource Appraisal program. Using a geology-based methodology, the USGS estimates the mean undiscovered, conventional petroleum resources in the province to be approximately 24 billion barrels of oil equivalent of crude oil, natural gas, and natural gas liquids.

This study specifically targets on two sections of Lower Cretaceous rocks located on the Chekurovka Cape (key section) and Chucha Cape. We documented the fluvial section in terms of sequences, consisted of low-accommodation and high-accommodation system tracts, where low-accommodation system tract is characterized by amalgamated channel belts and high-accommodation system tract is characterized by channel belts dispersed within fine-grained floodplain deposits. We identified four sequences in the Chekurovka Cape the Lower Cretaceous deposits. Each of the four sequences identified within the Chekurovka section was also identified within the Chucha Cape section. Although thickness of the individual sequences varies, all sequences with high and lower accommodation systems tracts are recognized and correlated between the two sections. This implies that the four underlying sequence boundaries can be regionally correlated within this foreland basin and likely extend beyond the boundaries or our study area as well. Variability in the available fluvial accommodation space probably was connected with variation of basin’s subsidence rate.

The problem of the maintenance of the production level, entailing the industrial development of new reservoir systems is vital in Western Siberia (Russia). Such targeted systems include the deep Neocomian deposits (Achimov Fm) and Late/Middle Jurassic reservoirs. Hydrocarbon fields occur in Neocomian sandstone lenses, disseminated within silt and marine shale deposits. These reservoirs, stratigraphically associated to a large and complex system of clinoforms, correspond to both deep-water sand facies of the Achimov Fm at the base of the slope, and deltaic and shoreface sandstones interbedded with shales at the top. They contain hydrocarbons originating from the Bazhenov Fm (20-70 meters), considered as the major source rock in this basin. Late Jurassic siliceous layers underneath the Bazhenov black shale constitute another reservoir system of interest. Accumulations were discovered in Late/Middle Jurassic sandy reservoirs, but their oil and gas habitats remain undervalued to date. These reservoirs, affected by fracturing and deformation, are characterized by a series of anticlines and synclines structures separated by sub-vertical faults.

Annotation. Seismic works and deep boring materials analysis points out penecontemporaneous formation of Astrakhan-Aktubinsk uplift zones (AAUZ) and absence of cuttings at the culms of atoll like carbon-bearing solid masses as of Tengiz type. Soline thikness accumulation of Kungurian age tookplace at deep-water basin (the depth in the central areas of Pre-Caspian lacune exceeds 1,5 km). Seismic works materials interpretation within AAUZ limits assumes existing of trottoir s at docungur cuttings. Coincidence in plane of these “ reefs” is seen and salt-dome structure s that contradicts peculiarities of such formations

Seismic-acoustic inversion of the CDP section of the 2-DV-A reference profile running from the Pevek (Chaun Bay) to the Valunistoye (Central Chukot) has resulted in basic dynamic and geometrical characteristics such as an average reflector dip, and integral reflector energy. It is established that the behavior of a crust-mantle layer «Moho» is quite accurately observed on the seismic acoustic section. The integral energy section appears to be useful for identifying crustal blocks. The analysis of reflector dips on the 2-DV-A profile has shown that in its northwestern part (0–200 km) in the crystalline crust the inclination of reflections prevails obviously to the southeast. In the interval of 200-205 km in the crystalline crust and uppermost mantle, the vertical column of reflections with the northwestern inclination serving as a sharp boundary between large blocks of the Chukchi microcontinent has shown itself clearly. From 390 to 520 km the northwestern reflector inclinations are dominant in the crystalline crust, which corresponds to the movement of microblocks of the Koryak accretionary belt. The use of basic seismic-acoustic attributes for geologic interpretation has supported the validity of the developed deep geologic-tectonic model of the earth’s crust of the northern and central Chukchi microcontinent.

The principal sedimentary basins of France result from a succession and/or combination of extensional or compressive and thermal mechanical evolution controls during the Alpine Cycle. The sediments filling these basins can be subdivided into second-order sequences recording the major geodynamic events that have marked the Mesozoic and Cenozoic geological history of Western Europe. The Mesozoic and Cenozoic sedimentary basins have been worked since antiquity for their multiple resources and have been the subject of outstanding geological syntheses since the 18th century. At the beginning of the 20th century, the geological information extracted the first deep water wells, combined with the cartographic data, gave us a three-dimensional picture of the basins. Thereafter, the proliferation of oil-exploration, gas-storage and geothermal-energy projects provided, in particular, 350,000 km of seismic lines and 6000 deep boreholes. France’s sedimentary basins are today basins for which we have a large amount of diversified data. They thus provide excellent playing fields for developing modern methodologies for 3D reconstruction of the deep geology by virtue of major societal projects and extensive scientific debate on the sedimentary recording of geodynamic events.

Global resources of hydrocarbons and other (coal, woods, water, etc.) energy sources are distributed irregularly. This depends upon geotectonic position of the region, historical and today’s climatic conditions, and upon some other reasons. Main resources are located in the large troughs of the Earth crust (sedimentary basins) with thick layer of deposits. Today most famous of them are Persian Gulf with vast adjacent territories, Near-Caspian Depression with the northern part of the Caspian Sea, Barents Sea, Western Siberia (central and northern regions) and adjacent offshore area of the Kara Sea. Mexican Gulf with its not yet fully explored resources is also included into this largest category. Further investigations will lead to discoveries of similar large basins in the Arctic too

Large changes of the depth of water of a third order in cratonic basins, up to 100-200 m during 1-3 Ma, are commonly supposed to be of a eustatic origin. Continuous deposition took place at a depth of ≤ 10-20 m in East Siberia in the Ordovician and Silurian, East Baltic in the Cambrian and Ordovician, and in the East European Platform in the Pennsylvanian and Early Permian. Modelling of changes in the depth of water in these regions under sea-level fluctuations of a third order has shown that over the predominant part of the above epochs such fluctuations did not exceed 20-30 m. Under such circumstances, large-scale regressions and transgressions, 1-3 Ma long, in cratonic basins should be attributed to rapid vertical crustal movements. For example, the crustal uplift of ~ 200 m followed by the subsidence to the initial level occurred on the shelf in the western part of the East European Platform in the earliest Pennsylvanian. Numerous stratigraphic traps were formed due to regressions and transgressions of a third order. In each hydrocarbon basin, their prospecting requires the studies of time and space distribution of rapid vertical crustal movements in the basin and in the adjacent areas.

Wave field anomalies detected in seismic lines in Upper Devonian – Lower Permian terrigenous – carbonate deposits of the Barents Sea are typical of marginal reefs and carbonate scarps. Seismic data analysis allowed us to outline possible areas of carbonate scarps development. There are mainly confined to steps and terraces of the ancient continental shelf and fringe deepwater non-compensated basins of the East Barents Trough and adjacent depressions. Elaborated regional paleo-environmental map for Late Devonian – Early Carboniferous of the Barents Sea Area was constructed on the base of seismic interpretation data and the results of the Sea bottom and onshore area geological and geophysical surveys. The geologic – geophysical data comparison revealed a noticeable resemblance of structural – geological and sedimentary characteristics of Upper Devonian – Lower Permian basins in the East Barents Trough and PriCaspian Depression. Thus there could be condition in the East Barents Sea Trough and its borders favorable for development of both carbonate – clayey oil source rocks and oil promising sedimentary traps in the form of reefs, confined to marginal scarps of carbonate platform and to the inner carbonate shelf.

The petroleum resource assessment of the East Barents Basin Province, recently completed by the U.S. Geological Survey, is based on the Total Petroleum System concept, which includes knowledge of source, reservoir, and seal rocks, and timing of petroleum generation, migration, and accumulation. Using this approach, the mean undiscovered, conventional, petroleum resource in the province is estimated to be approximately 62 billion barrels of oil equivalent of crude oil, natural gas, and natural gas liquids.