PIASKOWCE Z POGRANICZA PENSYLWANU I PERMU DOLNEGO NA POMORZU ZACHODNIM: DIAGENEZA I JEJ ROLA W TWORZENIU WŁAŚCIWOŚCI ZBIORNIKOWYCH

Abstract

THE SANDSTONES FROM THE PENNSYLVANIAN/LOWER PERMIAN TRANSITION IN WESTERN POMERANIA: DIAGENESIS AND ITS ROLE IN RESERVOIR QUALITYAbstract. The paper presents the results of investigations of sandstones observed between the Carboniferous Rega Formation and the Lower Permian Wielkopolska Volcanigenic Formation in West Pomerania. The results have been acquired using various analytical methods (polarizing microscope, CL, SEM, EDS ISIS, XRD, light element stable isotope, infrared analysis). The sandstones are represented mostly by quartz arenites. Apart from detrital grains (quartz, feldspars, lithoclasts), authigenic minerals are observed in the sandstones. They correspond to iron oxides and hydroxides, clay minerals (kaolinite/dickite, chlorite, illite), carbonate minerals (calcite, dolomite, ankerite), sulphate minerals and quartz.Anumber of processes have been identified, which affected the sandstones. These are mechanical and chemical compaction, cementation, replacement, dissolution and alteration of unstable components. The effects of the processes have been variously marked within the deposits, depending on the mineral composition, burial depth and temperature. As a result, two diagenetic stages can be identified: eo- and mesodiagenesis. The deposits may have been heated to the maximum temperatures of approximately 130C.