Ocena możliwości powstawania węglowodorów w mezozoicznych skałach macierzystych Niżu Polskiego
Abstract
EVALUATION OF POSSIBILITIES OF GENERATION OF HYDROCARBONS IN MESOZOIC SOURCE ROCKS IN THE POLISH LOWLANDS
Summary
The major horizons of potential source rocks in the Mesozoic from central parts of the Polish Lowlands were differentiated and tentatively evaluated on the basis of geochemical data and well-log correlations. The studies showed that rocks with good to intermediate parameters of source rocks for oil are present in the Upper Kimmeridgian, Lower Portlandian, Lower Keuper and upper parts of Muschelkalk and (but on a smaller scale) Lias clay series. The remaining horizons are characterized by pre-dominance of detrital material, more favourable for generation of gas.
Estimations of degree of maturity of hydrocarbons, alteration of kerogen, reflectance of vitrinite, and index of thermal-time alterations (TTI) showed that intense generation of oil could start in the horizons in central zone of the Polish Lowlands only. In the case of the Lower Keuper horizon, the geothermal conditions appropriate for generation of oil are found in much wider area, turning out to be sufficient event for the phase of condensate gases in central part of the basin. In turn, there is no evidence for initiation of the stage of oil generation in clay Lower Cretaceous horizons.
Summary
The major horizons of potential source rocks in the Mesozoic from central parts of the Polish Lowlands were differentiated and tentatively evaluated on the basis of geochemical data and well-log correlations. The studies showed that rocks with good to intermediate parameters of source rocks for oil are present in the Upper Kimmeridgian, Lower Portlandian, Lower Keuper and upper parts of Muschelkalk and (but on a smaller scale) Lias clay series. The remaining horizons are characterized by pre-dominance of detrital material, more favourable for generation of gas.
Estimations of degree of maturity of hydrocarbons, alteration of kerogen, reflectance of vitrinite, and index of thermal-time alterations (TTI) showed that intense generation of oil could start in the horizons in central zone of the Polish Lowlands only. In the case of the Lower Keuper horizon, the geothermal conditions appropriate for generation of oil are found in much wider area, turning out to be sufficient event for the phase of condensate gases in central part of the basin. In turn, there is no evidence for initiation of the stage of oil generation in clay Lower Cretaceous horizons.