Utwory permu dolnego zapadliska wielkopolskiego w świetle danych geofizyki wiertniczej
Abstract
LOWER PERMIAN DEPOSITS OF THE WIELKOPOLSKA BASIN IN THE LIGHT OF WELL LOGS
Summary
The paper presents the results of analysis of Rotliegendes deposits of the Wielkopolska basin, carried out on the basis of well logs. The studied profile was divided into two parts: lower and upper, corresponding to the Autunian and Saxonian, respectively. This subdivision was made with the reference to changes in geophysical parameters of rock series. The same principles were used in further subdivision of the Saxonian into 5 lithofacies horizons which made possible correlation of Rotliegendes deposits. The results obtained were subsequently used for drawing sketch maps of thickness of individual series and their sum, which gave approximate image of Saxonian sedimentary surface.
The data obtained showed that decrease in thickness of the Saxonian is connected with reduction of older correlative links. This results in greater extent of younger series than the older. The exceptions are here Solec Sandstones which differ from the remaining series in distribution and m ode of development. The Solec Sandstones occur in narrow zones stretching along morphological basement elevations in a limited area and are very close to sandy barriers in the mode of development. They are best collectors among Saxonian deposits. This is reflected by the porosity map made for the topmost 50 m of Saxonian section, on which the areas of the maximum values of Kp and the extent of Solec Sandstones coincide. Other deposits important from the point of view prospecting include Upper Red Sandstones and Younger, Conglomerate Series when reduced in thickness. Structural and stratigraphic traps may be expected in these horizons.
Summary
The paper presents the results of analysis of Rotliegendes deposits of the Wielkopolska basin, carried out on the basis of well logs. The studied profile was divided into two parts: lower and upper, corresponding to the Autunian and Saxonian, respectively. This subdivision was made with the reference to changes in geophysical parameters of rock series. The same principles were used in further subdivision of the Saxonian into 5 lithofacies horizons which made possible correlation of Rotliegendes deposits. The results obtained were subsequently used for drawing sketch maps of thickness of individual series and their sum, which gave approximate image of Saxonian sedimentary surface.
The data obtained showed that decrease in thickness of the Saxonian is connected with reduction of older correlative links. This results in greater extent of younger series than the older. The exceptions are here Solec Sandstones which differ from the remaining series in distribution and m ode of development. The Solec Sandstones occur in narrow zones stretching along morphological basement elevations in a limited area and are very close to sandy barriers in the mode of development. They are best collectors among Saxonian deposits. This is reflected by the porosity map made for the topmost 50 m of Saxonian section, on which the areas of the maximum values of Kp and the extent of Solec Sandstones coincide. Other deposits important from the point of view prospecting include Upper Red Sandstones and Younger, Conglomerate Series when reduced in thickness. Structural and stratigraphic traps may be expected in these horizons.