Lower Permian Carbonate Buildups in the Northern Timan–Pechora Basin as the Main Hydrocarbon Exploration Object

Abstract

Organogenic buildups named as carbonate mounds are widespread in Lower Permian deposits in the northern Timan–Pechora basin and are of great interest to the oil-and-gas industry as natural hydrocarbon reservoirs. Their distribution and textural features were controlled by seabed morphology, sea level changes, and specific paleoecology of the Early Permian period. In contrast to classic reefs, these buildups were not able to form large accumulative landforms that changed the hydrodynamics and paleogeography of sedimentary basins. The results of this study allowed us to divide the Lower Permian carbonate buildups into two types: (1) skeletal mounds formed primarily by algae and Palaeoaplysina communities; (2) microbial mounds composed of microbial assemblages. Identification of these mounds based on seismic data usually does not meet any difficulties. However, their texture, peculiarities of reservoir distribution, and variations of their properties are often unreflected in the characteristics of seismic waves due to limitations of the seismic survey resolution. The sedimentation modeling describes spatiotemporal relationships of the identified lithofacies characterized by different reservoir potential. Application of these results during the seismic interpretation increases significantly reliability of the forecast of carbonate reservoir properties.