Osram I - origin of sediment-related aeromagnetics I

INFO APRIL 2015

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OSRAM I – ­­­ ORIGIN OF SEDIMENT-RELATED AEROMAGNETICS I Magnetic properties of Mesozoic and Cenozoic sediments from the northern North Sea and the Norwegian Sea: measurements and interpretation.

The main aims of the project ‘OSRAM - Origin of Sediment-Related AeroMagnetics’ were to characterise and interpret variations in magnetic susceptibility and remanence in the Mesozoic and Cenozoic sediments offshore Norway and to identify the mineralogical source of the magnetic sediments.

Modern aeromagnetic surveys have revealed several sets of high frequency anomalies caused by magnetic sources within the sedimentary sequences. The incorporation of petrophysical data leads to more precise quantitative analysis, and reduces the inherent ambiguity in the interpretation of the aeromagnetic data.

Susceptibility measurements have previously been carried out on IKU/SINTEF cores from Shallow Drilling in the Helgeland and Lofoten areas.

The project is a collaboration between SINTEF Petroleum Research and NGU. The project is organised as a multiclient, spec-project with a fixed price.

In order to interpret and to be able to predict the magnetic properties the susceptibility measurements were combined with remanence measurements, lithological characterisations and mineralogical (including magnetomineralogical) analysis of selected samples having higher susceptibility.

SEM BEI of strongly altered and partly dissolved detrital grain of Fe-Ti oxide in sandstone from the Nordland area.

ORDERING: Price for late participants: 276,000 NOK

MORE INFORMATION?

ODLEIV OLESEN

ATLE MØRK

TORLEIF LAURITSEN

Team Leader, Continental Shelf Geophysics odleiv.olesen@ngu.no Tel: +47 990 91 743

SINTEF Petroleum Research NO-7465 Trondheim atle.mork@sintef.no Tel: +47 415 14 490

Senior Engineer, Continental Shelf Geophysics torleif.lauritsen@ngu.no Tel: +47 73 90 44 63

Locations of exploration wells and SINTEF shallow drill holes.

SEM BEI of magnetic siderite cement “flowers” (light grey colour) in kaolinitic mudstone matrix.

SAMPLE MATERIALS

DATA AVAILABILITY

Cores have been chosen in order to represent different stratigraphic formations in the Northern North Sea and the Norwegian Sea (total 1,864 m + 1,037 m). The SINTEF cores (total 3,396 m, access was subject to participation in actual drilling projects; Møre 1988, Stord 1988, Farsund 1988, Troms III 1990, Bjørnøya West 1989 and Nordland VI and Nordland VII) are included to supplement the lithological and stratigraphical variation and these cores include also a few locations in the southwesternmost Barents Sea. This gives a total core length of about 6,000 m.

The project results are presented in a main report which includes all data, as well as discussions and conclusions. The data are presented as tables, susceptibility logs and a compilation figure of magnetic properties in a stratigraphic and geographic framework. Digital data are delivered on a CD. Mineralogical analysis are presented as tables and SEM images. The magnetic properties are discussed in relation to mineralogy, lithology and stratigraphy and the properties are compared between the different areas.

SPONSORS BP, CoconoPhillips, Eni, ExxonMobil, Statoil, Total.

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PO Box 6315 Sluppen NO-7491 Trondheim Phone: +47 73 90 40 00

Leiv Eirikssons vei 39, Trondheim E-mail: ngu@ngu.no www.ngu.no /continental_shelf_geophysics

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