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.


Article metrics loading...

Loading full text...

Full text loading...


  1. BjørlykkeK.
    [2015] Petroleum Geoscience: From Sedimentary Environments to Rock Physics – Second Edition. Springer-VerlagBerlin Heidelberg.
    [Google Scholar]
  2. Carcione, J.M.
    [2000] A model for seismic velocity and attenuation in petroleum source rocks. GEOPHYSICS, 65, 1080–1092.
    [Google Scholar]
  3. Carcione, J.M. and Avseth, P.
    [2015] Rock-physics templates for clay-rich source rocks: GEOPHYSICS, 80, D481–D500.
    [Google Scholar]
  4. Dang, S. T., C. H.Sondergeld and C. S.Rai
    [2016] A New Approach to Measuring Organic Density. Petrophysics, 57, 112–120.
    [Google Scholar]
  5. Grieser, B. and Bray, J.
    [2007] Identification of production potential in unconventional reservoirs: SPE Production and Operations Symposium. SPE #106623.
    [Google Scholar]
  6. Hansen, J.A., Yenwongfai, H.D., Fawad, M. and Mondol, N. H.
    [2017] Estimating exhumation using experimental compaction trends and rock physics relations, with continuation into analysis of source and reservoir rocks: Central North Sea, offshore Norway: SEG, Expanded Abstracts, 3971–3975.
    [Google Scholar]
  7. Kalani, M., J.Jahren, N.H.Mondol and J. I.Faleide
    [2015] Petrophysical implications of source rock microfracturing. Internation Journal of Coal Geology, 143, 43–67.
    [Google Scholar]
  8. Mondol, N.H.
    [2018] Seal quality prediction using E-Poisson's ratio rock physics templet- A case study from the Norwegian Barents Sea. GeoConvention
    [Google Scholar]
  9. Perez, R.A. and Marfurt, K.J.
    [2015] Identification of brittle/ductile areas in unconventional reservoirs using seismic and microseismic data: Application to the Barnett Shale. Interpretation, 2, T255–T271.
    [Google Scholar]
  10. Skurtveit, E., Grande, L., Ogebule, O.Y., Gabrielsen, R.H., Faleide, J.I., Mondol, N.H., Maurer, R. and Horsrud, P.
    [2015] Mechanical testing and sealing capacity of the Upper Jurassic Draupne Formation, North Sea. 49th US Rock Mechanics/Geomechanics Symposium, ARMA, Expanded Abstracts.
    [Google Scholar]
  11. Vernik, L.
    [2016] Seismic petrophysics in Quantitative Interpretation. Society of Exploration Geophysicists.
    [Google Scholar]
  12. Vernik, L. and Landis, C.
    [1996] Elastic anisotropy of source rocks-implications for hydrocarbon generation and primary migration. AAPG Bulletin, 80, 531–544.
    [Google Scholar]
  13. Walles, F.
    [2004] A new method to help identify unconventional targets for exploration and development through integrative analysis of clastic rock properties. Houston Geological Society Bulletin, 47, 35–49.
    [Google Scholar]

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error