The integration of electrical image logs with core data for improved sedimentological interpretation

Abstract

Abstract Electrical borehole images allow the direct integration of sub-surface well-log data with core data on a detailed visual level. For sedimentary interpretation, electrical borehole images are primarily used to obtain bedding orientations and to confirm core-derived sedimentology. The aims of this paper are two-fold: firstly, to discuss how the sedimentological information provided by electrical borehole image logs is integrated with that obtained from other wireline logs and from cores; and secondly, to show that despite the need to integrate these data electrical borehole images can provide the geologist with unique sedimentological information which can not be obtained from either the cores or the other wireline logs. In a case study from the Oseberg Syd oil and gas field, a Fullbore Formation MicroImager (FMI Mark of Schlumberger) log through a complex interval of shallow marine sediments has been investigated. The interpretation of the FMI log led to the acquisition of very detailed orientation data related to the attitudes of sedimentary bedding surfaces. When these data were integrated with the sedimentary facies, identified from core description, they proved fundamental for understanding the activity of different shallow marine palaeocurrents during sediment deposition.