TY - JOUR
T1 - Shale fabric and organic nanoporosity in lower Palaeozoic shales, Bornholm, Denmark
AU - Henningsen, Lucy Malou
AU - Jensen, Christian Høimann
AU - Schovsbo, Niels Hemmingsen
AU - Nielsen, Arne Thorshøj
AU - Pedersen, Gunver Krarup
N1 - Funding Information:
Louise Belmonte, formerly at the Technical University of Denmark, is thanked for providing access to the FIB-SEM. This paper is a contribution to the GeoCenter Denmark projects 5?2015 and 3?2017.
PY - 2018/8/15
Y1 - 2018/8/15
N2 - 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 & Jensen (2017). The
shales are dry gas-mature (2.3% graptolite reflectance; Petersen et al. 2013) and have been extensively used as analogies for the deeply buried Palaeozoic shales elsewhere in Denmark (Schovsbo et al. 2011; Gautier et al.
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 c. 70 m thick gas-mature, organic rich succession (Ferrand et al.
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.
AB - 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 & Jensen (2017). The
shales are dry gas-mature (2.3% graptolite reflectance; Petersen et al. 2013) and have been extensively used as analogies for the deeply buried Palaeozoic shales elsewhere in Denmark (Schovsbo et al. 2011; Gautier et al.
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 c. 70 m thick gas-mature, organic rich succession (Ferrand et al.
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.
UR - http://www.scopus.com/inward/record.url?scp=85069485649&partnerID=8YFLogxK
U2 - 10.34194/geusb.v41.4332
DO - 10.34194/geusb.v41.4332
M3 - Article
SN - 2597-2154
SN - 1904-4666
SN - 1604-8156
VL - 41
SP - 17
EP - 20
JO - Geological Survey of Denmark and Greenland Bulletin
JF - Geological Survey of Denmark and Greenland Bulletin
ER -