Permeability model of tight reservoir sandstones combining core-plug and miniperm analysis of drillcore; longyearbyen co2lab, Svalbard

• Main Authors: Magnabosco C., Braathen A., Ogata K.
• Other Authors: Magnabosco, C., Braathen, A., Ogata, K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: De Geerdalen; Helvetiafjellet; Knorringfjellet; Longyearbyen; Rurikfjellet; Svalbard
• Online Access: http://hdl.handle.net/11588/820186

Permeability measurements in Mesozoic, low-permeability sandstone units within the strata cored in seven drillholes near Longyearbyen, Svalbard, have been analysed to assess the presence of aquifers and their potentials as reservoirs for the storage of carbon dioxide. These targeted sandstones are located in the Upper Triassic-Lower Jurassic De Geerdalen and Knorringfjellet formations, with some permeability found in the Cretaceous Rurikfjellet and Helvetiafjellet formations situated within otherwise impermeable cap-rocks. Permeability and porosity data were acquired from drill plugs, analysed in the laboratory by flooding of H2O, He and Hg, and compared with direct measurements collected manually from cores with a Miniperm instrument. The sandstones are tight (<2 mD) due to extensive diagenesis. The two methods produced permeability results of up to one order difference in magnitude; however, when correlated, these methods offer a robust linear relationship that can be applied as a correction function. Detailed mapping of drillcore with Miniperm, corrected by the proposed function, allows analysis of tight reservoir permeability on a very detailed scale, which identify otherwise unrecognised permeable zones. In the analysed reservoir sandstone succession, 2 out of 30 m has recognisable permeability above the threshold of the Miniperm. In the upper part of the reservoir (Knorringfjellet Formation), where data are from three closely spaced wells, the permeability field can be divided into through-going and isolated zones, of which c. 10% is through-going. In the explored Upper Triassic to Cretaceous succession of Central Svalbard, the Knorringfjellet Formation sandstones and conglomerates have the best matrix properties for storage of carbon dioxide.