Crustal and Upper Mantle Velocity Model along the DOBRE-4 Profile from North Dobruja to the Central Region of the Ukrainian Shield : 2. Geotectonic Interpretation

Peer reviewe

Petroleum potential of Lower Jurassic and Pre-Jurassic reservoirs of Ust-Tym megadepresion

The relevance of the research is caused by the need of reproduction of oilfields area resource base in southeast of Western Siberia. The main aim of the research is to identify and to propose the priority areas for exploration and development of oil and gas complexes of the Lower Jurassic and Pre-Jurassic in the poorly studied territory of Ust-Tym megadepression. Objects of researches  are the Lower Jurassic reservoir — layers Yu15 and Yu16, immediately contacting with maternal Togur suite, and Pre-Jurassic reservoir — collectors of Triassic weathering crust and collectors of Paleozoic basement. Methods of researches include reservoirs geomapping, analysis of generated oil density distribution, evaluation and analysis of density distribution reservoirs of primary accumulated oils, zoning of reservoirs according to the prospectivity degree. Systematized complex of geological and geophysical data on the object of research. The authors have given the volumetric-areal characterization for Lower Jurassic and Pre-Jurassic reservoirs —plotted the maps of the total thickness and quality collectors. Analyzed of generated oil density distribution, obtained based on the mapping by geotemperature criterion the paleo-sources of Togur deposits generation. The maps of distribution of relative density of the accumulated resources have been plotted and zoning for Lower Jurassic and Pre-Jurassic reservoir have been carried out. The areas of priority for searching have been proposed for Lower Jurassic the central part of Negotskogo mezoprogiba, for reservoir of weathering crust the northeast side of Ust-Tym megadepression, for reservoir rocks of the basement the north-eastern slope of the north-Parabel megamonoklinalii and the southern Pyzhinskogo mezodepression. Consistency of geophysical forecast data drilling is estimated at 95%. It has been concluded that the value of geothermal data is essential to solve a conceptual problem about the source of hydrocarbons