TY - JOUR AU - Henningsen, Lucy Malou AU - Høimann Jensen, Christian AU - Hemmingsen Schovsbo, Niels AU - Thorshøj Nielsen, Arne AU - Krarup Pedersen, Gunver PY - 2018/08/15 Y2 - 2024/03/29 TI - Shale fabric and organic nanoporosity in lower Palaeozoic shales, Bornholm, Denmark JF - GEUS Bulletin JA - GEUS Bulletin VL - 41 IS - SE - RESEARCH ARTICLE | SHORT DO - 10.34194/geusb.v41.4332 UR - https://geusbulletin.org/index.php/geusb/article/view/4332 SP - 17-20 AB - <p>In organic-rich shales, pores form during oil and gas genesis within organic matter (OM) domains. The porosity thus differs markedly from that of conventional reservoir lithologies. Here we present the first description of shale fabric and pore types in the lower Palaeozoic shales on Bornholm, Denmark. The pores have been studied using the focused ion beam scanning electron microscope (FIB-SEM) technique, which allows for high resolution SEM images of ion polished surfaces. Shale porosity is influenced by many factors including depositional fabric, mineralogical composition, diagenesis and oil and gas generation (Schieber 2013). Here we discuss some of these factors based on a study of lower Palaeozoic shale samples from the Billegrav-2 borehole on Bornholm (Fig. 1) undertaken by Henningsen &amp; Jensen (2017). The shales are dry gas-mature (2.3% graptolite reflectance; Petersen <em>et al</em>. 2013) and have been extensively used as analogies for the deeply buried Palaeozoic shales elsewhere in Denmark (Schovsbo <em>et al</em>. 2011; Gautier <em>et al</em>. 2014). The Danish lower Palaeozoic shale gas play was tested by the Vendsyssel-1 well drilled in northern Jylland in 2015. Gas was discovered within a <em>c</em>. 70 m thick gas-mature, organic rich succession (Ferrand <em>et al</em>. 2016). However, the licence was subsequently relinquished, due to a too low gas content. The present study confirms a close similarity of pore development between the shales on Bornholm and in the Vendsys sel-1 indicating a high porosity within this stratigraphic level throughout the subsurface of Denmark. However, the rather different development of porosity in the different shale units presents a hitherto neglected aspect of the Palaeozoic gas play in Denmark.</p> ER -