FORMATION CONDITIONS, SEDIMENTATION CYCLICITY, AND VOID MODELS OF FAMENNIAN DEPOSITS OF THE YUGOMASHEVSKOYE FIELD (Republic of Bashkortostan)
A.S. Dushin1, T.V. Burikova1,2, D.S. Tarnovetskii2
1Ufa State Petroleum Technical University, Ufa, Russia
2OOO RN-BashNIPIneft, Ufa, Russia
Keywords: Carbonate buildup, Famennian stage, facies, cyclicity, sediment genesis, secondary transformation, porosity, fracturing, leaching, Yugomashevskoye field
Abstract
The article summarizes new data on core studies and well logging in the Famennian deposits of the Yugomashevskoye field located in the Republic of Bashkortostan (Russia). Structurally, the subject is categorized as a model of a rimmed platform with characteristic organogenic buildups and associated facies. The identified sedimentation cyclicity, the secondary processes, and the analysis of changes in the relative sea level make it possible to identify the most common types of porosity confined to a particular part of the section and facies zonality. Transgressive and regressive parts of the cycles are characterized by their specific set of lithotypes and characteristic types of void space. It is revealed that the formation of a void space is affected by the duration and intensity of secondary processes: leaching, dolomitization, and claying associated with the subaerial exposure. Moreover, this work substantiates the division of carbonate structures of this region into three types that differ in terms position, morphology, and manifestation of hypergene transformations, as reflected in the differentiation of types of void space of host rocks and their potential in terms of reservoir characteristics.
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