Thin section analysis and effects of geothermal gradient to determine porosity and permeability in sandstone and limestone reservoir rocks

Authors: Abdulah G
Conference: European Geothermal Conference Session: Modelling, data analysis
Year: 2003 Language: English
Abstract: All of the reservoir assets including oil, gas, and geothermal energy are all depended upon the pore volume and the permeability of the reservoir rock. In this study, these parameters were determined by applying capillary pressure approach through digitally scanned microscopic images. Especially the existence of steam and liquid water in the reservoir make the capillary pressure approach more accurate for the determination of rock properties. The geothermal gradient may also participate in this approach, since the pore diameters of the rock masses change with the changing temperature. After 1500ft in Termin region where the samples were collected the pore diameter increased in 0.8% resulting in 2-5% increase in porosity values and thus converting more absolute permeability into effective permeability. By applying image analysis technique, the sandstone permeabilities were found as around 18%. In this study capillary pressure was considered as a function of the pore diameter. Each scanned pore area per total area was considered as saturation parameter. At least ten scans were performed for each thin section and at least 95% of all thin sectioned are was examined under microscope and 600 data were recorded for each field scan of the sample.
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