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Application at Development and Production and Scale |
1 3D Lab, School of Earth, Ocean and Planetary Sciences, Cardiff University, , Main Building, Park Place, Cardiff CF10 3YE, UK (e-mail: m.huuse{at}earth.cfac.uk)
2 Department of Geology and Petroleum Geology, University of Aberdeen, , UK
3 Statoil ASA, , Forushagen, 4035 Stavanger, Norway
4 Enterprise Oil Norge, , now at A/S Norske Shell, P.O. Box 40, 4098 Tananger, Norway
5 TotalFinaElf Petroleum Norge, , Finnestadveien 44, Dusavika, 4029 Stavanger, Norway
Post-depositional remobilization and injection of sand can significantly change the geometry of deepwater clastic reservoirs. Features associated with these processes are particularly well developed in the lower Paleogene of the South Viking Graben of the UK and Norwegian North Sea. Seismic scale sandstone intrusions can be grouped in two classes. Class 1 comprises low-angle (20-40 degrees) tabular sandstone intrusions emanating from steep-sided in situ sand bodies within the Balder Formation. The intrusions may be 5-30+m thick and crosscut 120-250+m of compacted stratigraphic section. They terminate at an unconformity at the top of the Frigg interval where they may have extruded onto the palaeo-seafloor. Class 2 comprises conical sandstone intrusions that emanate some 50-300+m upward from distinct apexes located 400-700+m above the nearest depositional sand body. The conical intrusions may have been sourced from underlying sand bodies by clastic blow out pipes. Both types of intrusions seem to adopt their particular geometry independently of (but occasionally exploiting) polygonal faults within the encasing mudstones. Sandstone intrusions may be highly porous and permeable and are thus important both as reservoirs and as plumbing within thick mudstone sequences.
