OIL AND GAS GEOLOGY Forecast of hydrocarbons non-folded traps in Upper Visean deposits of Dnipro-Donets depression
Favorable geological preconditions for accumulation of accumulative sand bodies-reservoirs were studied and conditions of formation of related to them lithological, stratigraphic and combined oil and gas traps on the slopes of large near-axial troughs. Features of the geological structure of Upper Visean deposits on the northern slope of Ordaniv trough were investigated. A complex methodology of detecting non-anticlinal hydrocarbon traps, which includes paleotectonic, paleogeographic methods,
... ographic methods, detailed correlation of natural reservoirs by logging data and 3D seismic prospecting, as well as attributive analysis of the wavefield. The case of peripheral part of the West Solohivske gas-condensate field (GCF) shows the effectiveness of the new complex methodology. The hydrocarbon potential of Upper Visean terrigenous deposits was assessed for the area of Ordaniv trough northern slope in the area of West Solohivske structure. Despite the fact that all the known anticlinal structures have been already known, it is possible to find at their periphery new non-folded traps of hydrocarbons (HC). As estimated, these traps contain over 75% residual resources of hydrocarbons of Dnipro-Donets depression (DDD) . So, the forecast and discovery of these traps is very important for increase of the resource base of the gas industry of Ukraine. For this purpose we developed the complex methodology based on paleotectonic, paleogeographical methods, lithofacies analysis, detailed correlation of its sand tylosis reservoirs according to data of borehole geophysics (BGP) and high precision 3D seismic survey. A new method was successfully tested in the West Solohivske Structure which had been well surveyed by drilling and had the detailed 3D seismic survey. The structure is located in the DDD axial zone and associated with the Solokha-Dykan anticlinal trap. In oil and gas relation the West Solohivske Structure belongs to Glynsk-Rozbyshiv oil and gas area. The Upper Visean stage terrigenous deposits are regionally oil and gas bearing in the DDD axial zone .