The work intends to develop a conceptual model of the Permo-Carboniferous deposit of the Usinskoye field. In the furtherance of this goal, the authors have addressed the tasks of designing a specialised table format to describe thin sections of carbonate core samples and create a database based on the developed format for the subsequent analysis. The paper deals with studying the Permo-Carboniferous deposit of the Usinskoye field, located in the Komi Republic. A unique database of 1,710 described thin sections from 12 wells was created based on the developed format. The classification of carbonate rocks by R.J. Dunham supplemented by Embry and Kloven (based on the dominating fabric in limestone, type of cementing agent and their relationships in the rock) was used as a basis. According to rock material compositions and textural properties, the following nine rock lithotypes were identified: Mudstone, Wackestone, Packstone, Grainstone, Boundstone, Floatstone, Rudstone, Crystalline Carbonate (Dolomite), and Clayey Carbonate Silicite. By following the rock lithology type identification results and the seismic data, three main facies zones were determined in the section of the mid- Carboniferous and Lower Permian sediments: carbonate shoal (inner ramp zone), organogenic buildup (middle ramp zone) and shallow marine shelf plain (mid-ramp zone, partially outer ramp zone). A moderately deep marine shelf plain facies (outer ramp zone) was provisionally defined. Following the study results, two profiles of the Mid-Carboniferous and Lower Permian sediments of the Usinskoye field were plotted along two well lines. The presented sections support the conceptual model developed. Based on the core sample findings, the zone of organogenic build-ups stands out in the eastern part of the field, dating back predominantly to the Late Carboniferous and Early Permian periods. An inner ramp with the carbonate shoal facies supposedly exists in the field north-west. The conducted work has resulted in the development of a conceptual model of the Permo-Carboniferous deposit of the Usinskoye field, which can be used for further development of more reliable 3D facies models, commercial-scale estimations of reserves and field development designs.
ORTHOPTERA FROM THE LOWER PERMIAN VORKUTA LOCALITY (RUSSIA: KOMI REPUBLIC; KUNGURIAN STAGE)