Chapter 11
Resistivity Image Data, Vring Basin, Offshore Norway

Ian Goodall
Badley Ashton & Associates Ltd.
Horncastle, U.K.
Currently with Goodall Geoscience Ltd., Horncastle, U.K.

Ian Westlake
Badley Ashton & Associates Ltd.
Horncastle, U.K.

Grete Block Vagle
Ivar Mundal
BP Norge AS
Forus, Norway

Matthew Mulcahy
Schlumberger Wireline & Testing
Aberdeen, U.K.

ABSTRACT

The Luva Discovery well, 6707/10-1, targeted the Santonian to Campanian Nise Formation on the Nyk High structure in the Vring Basin, offshore Norway. It encountered a 156-m gas column in a section 1200 m thick, dominated by sheet sandstones of excellent quality deposited in a basin-floor complex. This section comprises stacked sand systems, each as much as 200 m thick, that have been mapped across the Vring Basin. They are separated by hemipelagic "fines blankets" deposited during periods of shutdown in sand supply. Vertical transmissibility in the sheet sandstones and hence potential reservoir performance are controlled by the extent of sand-body amalgamation and the distribution of caps to individual, dewatered high-density turbidite beds. These caps range in composition from glauconitic, carbonaceous-rich, and mud-prone/mudclast-rich sandstones to heterolithic deposits/shales and have markedly different vertical permeabilities ranging from less than 1 to about 1000 md. These bed caps have nondiagnostic conventional open-hole log responses, but are identified easily on Formation MicroScanner (FMS^*) images. In addition, the analysis of paleotransport directions derived from trough cross-stratified, glauconitic sandstone-bed caps--interpreted as lower-density deposits associated with waning flow and identified using the FMS images--provides a mechanism to test regional paleogeographic interpretations made from 3-D seismic data. The results are not conclusive, but they highlight uncertainties in the model for sand supply and dispersal in the Vring Basin.