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Cap Rock Evaluation of Central North Sea Shales, Through Log-Derived Poisson's Ratio and Young's ModulusNormal access

Authors: J.A. Hansen, J.R. Johnson and N.H. Mondol
Event name: Sixth EAGE Shale Workshop
Session: Poster Session 1
Publication date: 28 April 2019
DOI: 10.3997/2214-4609.201900269
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 511.11Kb )
Price: € 20

We present an evaluation of shale dominated cap rocks relevant for Middle Jurassic sandstone reservoirs in the Central North Sea, based on well log data from the Norwegian Continental Shelf. Previously established indicators for brittleness and seal quality, E (Young’s modulus) and ν (Poisson’s ratio), are utilized in the analysis. Similar ductile to fairly ductile behaviour is found in different formations for five analysed wells, of which two are oil discoveries, one contains only oil shows, and two are dry. Cap rocks in the discovery wells are comparatively most brittle, compared to a published E–ν template. Uplift of ~500 m in one of the discovery wells is not found to have compromised the sealing capability. We also investigate how organic content influence an organic-rich shale interval in terms of cap rock properties by using kerogen substitution and comparing to the other more organic-lean shales, which does not support a direct correlation between TOC and ductility. Finally, we consider how observed properties of different shales relate to different mineralogical composition.

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