Pore space analysis
Thin sections from a sandstone (so-called “Weißer Mainsandstein”) treated with a shape charge were investigated by image analysis (using the free software ImageJ) based on optical and scanning electronic microscopy for their porosity, pore size and permeability. We focussed on the crushed zone around the perforation channel in comparison with the untouched sandstone.
Porosity of the untouched sandstone is roughly 9 area-%. Within the crushed zone around the perforating channel porosity is significantly higher: approximately 15 area-%.
Pore size distribution also differs significantly for the untouched sandstone and the crushed zone: thin sections from the untouched sandstone show their maximum number of pores at a pore size of 5*102 to 5*103 µm2. Pores in the crushed zone tend to be taller than in the untouched zone: here the maximum lies in the pore size class 5*103 to 5*104 µm2.
Average pore shapes are very similar for the untouched sandstone and for the crushed zone: in both cases the average pore is slightly elongated. According to Anselmetti et al. (1998) from pore shapes permeabilities can be derived. They range between 60 and 100 mD, for both the treated and the untreated sandstone. Consequently, permeability is not increased by the treatment with shape charges. However, the crushed zone is much more enriched in elongated micro cracks than the untouched rock. These elongated cracks are parallel with the perforation channel and the bedding planes.
From the porosity investigations, specimens from the untouched sandstone and from the crushed zone can be distinguished easily.
Quartz grains in the specimens affected by the application of the shape charges (BSE images 03 and 04 to the right) are considerably fractured and disintegrated. Moreover, diagenetically grown clay minerals within the pore space can be observed in the high magnification detail BSE images 02 and 04. Feldspar and quartz can be distinguished by their different grey shades (feldspar: light, quartz: dark) which are the result of the mass dependent, so-called Z-contrast. Bright spots in the overview BSE image 03 are the result of electric charging due to the lack of carbon sputtering. In contrast, the detail BSE images 02 and 04 were photographed and investigated with carbon sputtering which avoided electrical charging of the thin sections.
News
With the recent acquisition of the state-of-the-art DIL 502 Expedis® Select thermal dilatometer from Netzsch, we are expanding our capabilities for the precise analysis of the thermal properties of rocks and mineral materials. We are now able to determine the coefficient of thermal expansion in accordance with DIN EN 14581:2004, ASTM D4535-13e1. (2013) or using a measurement program specifically tailored to the customer’s needs (for more information, see Thermal Dilatometer).
The project, which was funded by the Free State of Thuringia, was co-financed by the European Union through the European Regional Development Fund (EFRE).
This year’s EAGE GET Conference and Exhibition is taking place in Germany:
Gesteinslabor Dr. Eberhard Jahns will again be taking part as an exhibitor this year. From 2 to 6 November 2026, you can find us at Stand 31 at the HCC in Hannover.
We would be delighted to welcome you to our stand.
Gesteinslabor Dr. Eberhard Jahns is project and research partner within the HENRI (Hydrogen Energy Reservoir) project.
Our main focus is on determining the impact of H2 on the cap rock. Besides other parameters, we measure the capillary threshold pressure using various gases and gas mixtures of hydrogen and methane.
Results were presented at the third HENRI conference in Bratislava in September 2025
We are pleased to be part of the Dutch subsurface research for geothermal heat SCAN.
Further information can be found on the official homepage:
https://scanaardwarmte.nl/english/
