A pre-development turbidite reservoir evaluation using FMS electrical images

Abstract

FMS (Formation MicroScanner) electrical images in a single well from a familiar, deep marine North Sea Palaeogene section are illustrated. More than 900 m of good quality images were acquired through an interval from the Palaeocene Ekofisk Formation to the Eocene Grid Formation in a well from the centre of the South Viking Graben, Norwegian sector. The information that was obtained from these images is illustrated and discussed in terms of lithology, sedimentary structures, stratigraphy and petrophysics. The information on this deep marine, mainly gravity deposit succession, is considerably enhanced using image interpretation. Lithological information includes an improved net-to-gross ratio and an understanding of lithological heterogeneities. Sedimentary structure information includes the geometrical and lithological characterization of slumped intervals and a detailed description of evolving gravity deposit sequences. In terms of stratigraphy, illustrative images are shown of the Balder, Lista and Sele Formations. Some of the key surfaces of the Palaeogene interval, used for correlation and sequence stratigraphy, are shown in detail, especially the surface at the base of the Balder Formation and the boundary between the Lista and Sele Formations. The effect of hydrocarbons on the images is illustrated and used qualitatively in petrophysical terms to define the hydrocarbon-water contact.