NEW OIL AND GAS Plays IN THE CIS-URALS
K.O. Sobornov
OOO Severo-Ural’skaya Neftegazovaya Kompaniya, Moscow, Russia
Keywords: Hydrocarbon traps, blind thrusts, reefs, dislocated diapirs, lowstand sea level complex, seismic interpretation
Abstract
The search for oil and gas in folded zones and in the foredeep of the cis-Uralian region for many decades was reduced to drilling quite easily identified anticlinal structures and reefs located at shallow depths. Many important discoveries were made as a result, but the overall effectiveness of the work remained relatively low. On the one hand, this was due to the insufficient information content of the data for reliable preparation of structures in regions of complex structure. On the other hand, the peculiarities of the development of oil and gas systems in these regions were ignored during the assessment of prospecting sites. In comparison with traditional producing centers in the platform regions of the Volga-Ural and Timan-Pechora basins, this distinguishing feature was caused by a thicker sedimentary cover, the variability of its composition and structure, and multiple phases of structural development. Many failures were due to the formation of traps after the passage of the primary migration flow of oil and gas, low capacity of reservoirs, and their breaching by faults. As shown by interpretation of new geodata using modern knowledge about the oil and gas potential of regions of similar structure, the cis-Uralian region contains poorly studied oil and gas accumulation zones that can contain large deposits. These include blind thrust regions, subsalt traps in zones of dislocated diapirs, and also stratigraphic and combined traps associated with unconformities and facies changes. The utmost attention is paid to new prospecting objects in the Timan-Pechora basin in which the thickness of the Paleozoic cover has increased. The delineation of new promising objects in these zones has become possible due to new knowledge and better geophysical data.
|