Total Organic Carbon and Gamma Radioactivity Distribution of the Rudov Beds Formation within the Area Adjusted to Yablunivske O&G Field (Dnieper-Donets Basin)

Abstract

SUMMARY Rudov Beds is an organic rich formation within the Upper Visean (Lower Carboniferous) sedimentary complex located in the Dnieper-Donetsk basin (DDB). Its stratigraphic relation is still debatable. Rudov Beds are related to the tops of XIII Microfaunistic horizon, or related to basal part of XIIa Microfaunistic horizon. Rudov Beds are associated with play known as so-called “productive horizon V-23”. In the central part of the DDB Rudov Beds are overlying the Lower Visean carbonate formation, which was formed under the conditions of the carbonate platform. The uniqueness of regionally distributed Rudov Beds is associated with their unusual siliceous-carbonate and siliceous-shale composition, the presence of biogenic silicites; high organic matter content of mixed composition and high gamma activity. Vertically and laterally distribution of total organic carbon content (TOC) were determined according to the results of well logging data interpretation within the area Yablunivske oil and gas field. The features of the natural radioactivity of the Rudov Beds were investigated; its variability and its relation to the TOC content were analyzed. A regular trend was been identified of increasing the TOC content at 2x times towards the western part of the Yablunivske field area, which can indicate both the formation of sediments in isolated shallow sea conditions and the erosion of their upper part as a result of a break in sedimentation process. The statistical analysis shows that the anomalous values of gamma ray (GR) in the lower part of the Rudov Beds have a specific genesis, which is not correlates with the organic matter content.