Prospects for the oil content of traps associated with bed wedging out in the zones of pre-Visean erosion paleo-incisions within the Udmurt Republic

UDK: 553.982.23
DOI: 10.24887/0028-2448-2022-10-6-9
Key words: erosive remnant, paleo-incision, non-anticlinal trap, wedging out, deposit, field
Authors: A.A. Chikhirin (Izhevsk Petroleum Scientific Centre CJSC, RF, Izhevsk), V.V. Firsov (Udmurtneft JSC, RF, Izhevsk), A.V. Shostak (Izhevsk Petroleum Scientific Centre CJSC, RF, Izhevsk)

The article provides information on the results of geological prospecting within the Elnikovskaya area of the Elnikovskoye field in the southeast of the Udmurt Republic. Over the past 2 years, three deposits have been discovered in this area in the section of the Radaevian horizon of the terrigenous sequence of the Visean stage, associated with the stratigraphic type of traps adjacent to the unconformity. Non-anticlinal traps are confined to the wedging out of sandstone layers on the slopes of erosive carbonate remnants of the Tournaisian age. On the example of the territory of the Arlan carbonate paleoplateau, a possible mechanism for the formation of erosion partial barriers as a result of the activity of the paleo-river system and erosion-karst processes is shown. The destruction of carbonate deposits of the Tournaisian-Upper Famennian age in this area can reach 100 meters or more. An assumption is made about the probable role of erosion incisions as channels for the lateral migration of hydrocarbons from the zones of development of oil source rocks within the basins of the Kama-Kinel system to the limits of the marginal parts of the paleo-shelf. The characteristics and main parameters of new deposits are given. It is noted that according to morphological features, their ring and visor types are distinguished. The local nature of development and the small size of deposits in the plan also determine the small resource volume of such traps. However, as the statistics of discoveries of recent years in the Volga-Ural region show, in terms of reserves, these objects are of commercial interest. Within the area the presence of an existing well stock allows additional study of identified and search for new similar deposits by drilling sidetracks, often they can be additional when drilling overlying ones.

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