Geochemical characterisation of porosity cycles. DHRTC Sprint Project

Research output: Book/ReportReport (publicly available)

Abstract

The objective of this study was to investigate the geochemical composition of chalk in which porosity cycles occur. This has been done by analysis of 66 element abundances in 146 samples from the upper Maastrichtian chalk in the M-10X (Dan field) and the E-5X (Tyra field) wells. In the cyclic laminated-bioturbated part of the chalk, in-phase variation between porosity and the biomottled fabric is observed. In addition to this, many elements also exhibit an in-phase variation with the degree of biomottling. Laminated chalk is porous and characterised by low contents of Al and of elements belonging to the Rare Earth Elements (REE) group suggesting overall low clay content within this chalk type. Bioturbated chalk is less porous and characterised by high Ba and Mg content. The elements K, Th and U are recombined into total gamma (GR; K, Th and U) response and clean gamma (CGR; only K and Th) response. The laminated chalk has high total GR responses whereas the bioturbated parts have high CGR responses.
Original languageEnglish
Place of PublicationCopenhagen
PublisherGEUS
Number of pages82
DOIs
Publication statusPublished - 17 May 2018

Publication series

SeriesDanmarks og Grønlands Geologiske Undersøgelse Rapport
Number9
Volume2017

Keywords

  • Denmark

Programme Area

  • Programme Area 3: Energy Resources

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