Nesina N. The reconstruction of formation conditions of local geological bodies in the Carboniferous of the Don-Dnieper Downwarp according to the results of seismic facies analysis (connected with petroleum potential)

Results of seismic-facies analysis application in the different parts of the Don-Dnieper Downwarp and detailed description of the geological and facial conditions of accumulative objects formation are presented in the thesis. The process of geological interpretation of seismic images and attributes enables the analysis of the configuration, spacing of the accumulative objects location, as well as making conclusions about their genesis and forecast of potential hydrocarbon traps locations. Seismic facies are the seismic units, composed of groups of reflections, whose parameters differ from those of adjacent facies units. Seismic facies analysis is the description and interpretation of seismic reflection parameters, such as configuration, continuity, amplitude, and frequency, within the stratigraphic unit. Its purpose is to determine all variations of seismic parameters in order to determine lateral lithofacies changes. Reflection pattern geometries are the most useful for correlation with lithofacies interpreted from well logs, cores, and cuttings. According to the results of seismic-facies analysis, applied in the Myagkivska field of the Central Part of the North Board of the Dnieper-Donets Basin (DDB), expected local accumulative objects were outlined. For seismic-facies analysis, the seismic cube slices along the seismic horizon (horizon slices) were used. These slices characterize the amplitude variations within the small time interval (2 ms) that can be identified by the thin layer (up to 5 m). Logical analysis of the horizon slices permits the mapping of amplitude anomalies, connected with the lithology changes. It gives the possibility to analyze and to trace their extension within the interval of geological interest. Another expected local sand object was also reflected as amplitude anomalies on the horizon slices in the interval of the Lower Part of Moscovian Layer of the Middle Carboniferous. Based on the data of seismic-facies analysis, carried out in the Sukhodilska area of the North-Donetsk Fault zone, an enhanced seismic-facies map was created. It accurately localizes a predictable reef structure, lagoon, shallow and deep-water facial zones. Interpretation of the data received and published previously provided identifying patterns of biogerms occurrences within the area under research and allowed for an updated map of the Late-Serpukhovian biogerms distribution. Volume classification procedure of seismic-facies analysis was applied in the Livenska field of the Central Part of the DDB Southern Near-Edge Zone. Based on the data of seismic-facies analysis the seismic-facies map was calculated and the area of the carbonate massif was outlined. Seismic-facies analysis was carried out in the South-East part of the DDB. Based on the analysis of the seismic-facies maps, vertical sections and horizon slices with amplitude anomalies, the areas of expected paleo-channels location in the intervals of the Middle and Upper Carboniferous were identified.