Types of hydrocarbon fields in the southern part of Pre-Urals foredeep

In the southern part of the Pre-Urals foreland basin, more than fifty oil and gas fields have been discovered in the Permian, Carboniferous and Devonian deposits. In the north of the territory under consideration, in the Yuryuzano-Sylvenskaya Depression, the productive deposits are mainly represented by those Middle and Upper Carboniferous. The fields are associated with local uplifts situated on the structural-tectonic terraces step-by-step sloping down eastwards. Further southward, within the Belskaya Depression and the Shikhano-Ishimbayskaya Saddle, the fields are associated with the Tournaisian-Frasnian and Artinskian deposits. Pools of the structural and structural-tectonic types are widespread. Many fields are confined to the organogenic buildups. Within the Mrakovskaya Depression, three types of fields are identified. The first type fields occur in the depression’s western part and associated with the Sakmarian-Artinskian reef massifs. The second type fields are found in the east and associated with anticlinal folds in the hanging walls of thrusts (Kinzebulatovsky type). The third (Beloglinsky) type fields of the central part of the Mrakovskaya Depression occur between the western flank and overthrust structures of Southern Urals. In these fields, hydrocarbons are concentrated in the fractured limestones of the Ardatovsky horizon. Prospects of the territory under consideration are associated with the following geological features: Riphean, Vendian and Lower Paleozoic deposits having poor exploration maturity; autochthonous parts of thrusts in the western framing of Southern Urals; Lower Permian organogenic buildups; and flysch deposits infilling the Pre-Urals foreland basin. It should be noted that no studies have been carried out in in the Pre-Urals foredeep to assess the prospects of unconventional hydrocarbon sources, for example, the Domanic bituminous shales