Methodology of Formation MicroScanner image interpretation in Claymore and Scapa Fields (North Sea)

Abstract

Abstract The Formation MicroScanner (FMS) * tool is an advanced dipmeter tool capable of producing high-resolution resistivity images of a borehole wall. When integrated with core and open hole logs, FMS images are of great utility in evaluating the thin bedded reservoir sequences of the Claymore and Scapa North Sea oil fields. Sedimentary features as small as 0.5 inches (1.2 cm) can be resolved on FMS images. Such detail is employed in the distinction of massive, parallel laminated, ripple cross-laminated, bioturbated and conglomeratic bedding types. The application of the FMS tool to reservoir description is not limited to bedding type identification. Bed boundaries, as well as small and large scale structural features, can be distinguished, including erosional contacts, slumps, fractures and faults. In the hydrocarbon-bearing zone permeability distribution outwith cored intervals can inferred. This can be confirmed by relating resistivity changes to core measured permeability values. The proposed approach to FMS interpretation involves the integration of all available open hole logs with detailed local geological knowledge and core data. Aspect and image quality of the FMS log are important considerations. By imaging the borehole wall, the aspect of the FMS tool provides a direct method of relating features detected using open hole logs to those observed in cores. Image quality is largely dependent on resistivity contrast in the formation and correlation with cores is imperative to establish confidence limits for extrapolation into uncored intervals.