Show simple item record

dc.contributor.authorHansen, Jørgen André
dc.contributor.authorMondol, Nazmul Haque
dc.contributor.authorTsikalas, Filippos
dc.contributor.authorFaleide, Jan Inge
dc.date.accessioned2020-08-12T06:07:09Z
dc.date.available2020-08-12T06:07:09Z
dc.date.created2020-08-11T16:20:07Z
dc.date.issued2020
dc.identifier.citationMarine and Petroleum Geology. 2020, 121 .
dc.identifier.issn0264-8172
dc.identifier.urihttps://hdl.handle.net/11250/2671529
dc.description.abstractOur analysis of a comprehensive well log database and complementary mineralogical and geochemical information indicates that the risk for Upper Jurassic shales on the Norwegian Continental Shelf (NCS) to permit severe leakage of hydrocarbons from the reservoir is generally low, even in the case of substantial uplift. The content of brittle minerals, organic content, and compaction are dominant factors that explain the observed discrepancies in acoustic properties of organic-rich caprock shales. In particular, variations in silt-clay content in clay-dominated shales are found to primarily influence sonic velocity and to correlate closely with gamma-ray where the uranium contribution is limited (“grey shales”). Changes in organic content exhibit a stronger density-component and are seen to counteract or mask the compaction effect on velocity and density in Kimmeridgian black shales. The Hekkingen, Draupne and Tau formations are distinctly different from the underlying grey shale formations in acoustic properties, despite that the latter group also contains significant amounts of organic matter. Based on the low permeability and high capillary sealing capacity of clay-dominated shales, we conclude that even for a silty seal, migration through the caprock matrix is highly unlikely. Furthermore, tectonic fracturing is an ineffective leakage mechanism when the seal is poorly consolidated/cemented prior to uplift. Brittleness, related to both mineralogical composition and consolidation, is consequently a crucial parameter for predicting seal integrity in exhumed basins. Our rock physics framework and interpretations relate this rather qualitative parameter to acoustic properties, and thus, to seismic data.
dc.language.isoeng
dc.titleCaprock characterization of Upper Jurassic organic-rich shales using acoustic properties, Norwegian Continental Shelf
dc.typePeer reviewed
dc.typeJournal article
dc.description.versionpublishedVersion
dc.source.pagenumber18
dc.source.volume121
dc.source.journalMarine and Petroleum Geology
dc.identifier.doi10.1016/j.marpetgeo.2020.104603
dc.identifier.cristin1822833
cristin.ispublishedtrue
cristin.fulltextoriginal
cristin.qualitycode1


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record