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1 Schlumberger Log Services B.V., Woodlands Drive, Kirkhill Industrial Estate, Dyce, Aberdeen AB2 0ES, UK
2 Schlumberger, 1 Kingsway, London WC2B 6XH, UK
3 Department of Petroleum Geology, University of Aberdeen, Marischal College, Aberdeen AB9 1AS, UK
The small probe tip size of the nitrogen probe permeameter (typically 4 mm internal diameter) facilitates the investigation of small volumes of reservoir rock in core samples. The nitrogen probe permeameter measures gas flow rate at a known delivery pressure. This gas flow rate can in turn be calibrated to permeability. A closely spaced grid of such permeability measurements sampled every 4 mm in the x and y directions provides a basis for detailed sandstone permeability characterization. This paper presents permeability images, generated from such datasets, that reveal primary bedding fabric even where such features were not visually apparent in rock samples. A strong correlation is reported herein between images generated by probe permeametry from core samples and microresistivity images acquired from the borehole wall for the same reservoir interval. The similarity of features revealed by permeability and microresistivity images suggests a strong correspondence to rock properties measured by both techniques. Permeability images therefore offer considerable potential for the geological verification of microresistivity images where their direct interpretation is ambiguous. Furthermore, permeability and microresistivity images provide a mechanism for locating petrographical sampling points from which the controls on the permeability heterogeneities can be established.
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