Pore and Grain Geometry Analysis of Sandstone Reservoir Rocks from a Well of a Northern German Basin

Abstract

Pore space and grain geometry are important physical properties distinguished in reservoir rocks, particularly in sandstones, due to their influence on oil and gas reservoir quality. Therefore, a detailed study of pore space morphology and grain surface roughness in sandstone reservoir rocks is a key element in petroleum geology. It is eminent in understanding of the adhesion of hydrocarbons in rocks and coupled fluid flows in pores and along grain surfaces.

In this work, sandstone samples taken from a well of a Northern German basin deposit have been analysed by thin section petrography, Confocal Raman Microscopy and Confocal Laser Scanning Microscopy (CLSM). The roughness of grain surfaces is analysed and the pore geometries of sandstone rocks are verified. Roughness and pore geometry have a significant impact on the wetting behaviour and adhesion properties of hydrocarbon fluids, water or carbon dioxide (CO₂) to the pore walls.

The results show the relationship between the composition of sandstones and their pore geometry and the grain surface roughness. The geometry of the pore morphology and the grain surface shows a range from very rough to flat smooth crystal facets, from few hundreds to sub-micron, depending on the scale of observation. The 50x and 100x magnifications were applied in this study. The findings offer a detailed insight into the relationship of pore space morphology and the grain surface roughness. The results add important parameters to the calculation models for hydrocarbon exploitation and to enhancement of the amount of oil recovery.