1. Thermal Conductivities and Thermal Diffusivities Measured in Cores
from Two Boreholes Drilled in the Hurd Peninsula of Livingston Island
(Maritime Antarctica)
(1) Geophysical Centre of Evora, University of Evora, Evora, Portugal, (2) Department of Physics and Geophysical Centre of Evora,
University of Evora, Evora, Portugal, (3) Centre for Geographical Studies, University of Lisbon, Lisbon, Portugal, (4) Department of
Physics, University of Alcalá, Madrid, Spain, (3) Centre for Geographical Studies, University of Lisbon, Lisbon, Portugal
INTRODUCTION
Two boreholes were drilled, with continuos coring to collected as many samples as possible
for laboratory studies, near the Bulgarian Antarctic Base (BAB) of St. Kliment Ohridski, in
the Hurd Peninsula in the Island of Livingston (Maritime Antarctica) under the framework of
the PERMANTAR (Permafrost and Climate Change in the Maritime Antarctic) project. The
PERMANTAR project is one of the Portuguese aid to the core projects ANTPAS (Antarctic
and Sub-Antarctic Permafrost, Soils and Periglacial Environments) and TSP (Permafrost
Observatory Project – Thermal State of Permafrost) of the International Polar Year. Here the
results of the first measurements performed in cores collected in two boreholes drilled on a
CALM site (with coordinates 60º21’44.3’’W 62º38´48.5’’S, figure 1) and PAPAGAL site
(with coordinates 60º21’49.3’’W 62º38’54.2’’S Figure 1) are present. The boreholes distance
from each other coarse 187 metres, (figure 1).
The thermal conductivity and thermal diffusivity are two physical properties of rock
materials that are related to how thermal energy is transmitted through them, and so they also
fundamental to describe and understand energy transfer in soil and, in particular, in
permafrost areas. Thermal conductivity is a measure of the efficiency with which materials
conduct heat energy; thermal diffusivity measures the efficiency with which materials lose or
absorb energy. For isotropic and homogeneous materials thermal conductivity () can be
defined by the quotient between the rate at which heat is conducted through the unit area (q)
and the temperature gradient or the change in the temperature with depth (∆T).
Figure 1: CALM site and PAPAGAL site location. (a) Drilling on Livingston Island The thermal diffusivity (α) depends on the thermal conductivity () according to the
following expression:
where ρ is the density and Cp is the volume heat capacity.
Paulo Amaral amaral.paulomaciel@gmail.com (1), António Correia correia@uevora.pt (2),
Gonçalo Vieira gtvieira@ceg.ul.pt (3), Miguel Ramos miguel.ramos@uah.es (4),
Alexandre Trindade alexandretn@gmail.com (3)
Table 1: Thermal conductivity, thermal diffusivity (dry samples), and heat production values for the cores collected in the
CALM and Papagal sites boreholes, Livingston Island. TCa, TCb, and TCc, and, TDa, TDb, and TDc refer to the
measurement directions of thermal conductivity and thermal diffusivity, respectively, along (a), (b), and (c) directions of
Figure 2.
Figure 2: Directions
of measurement of the
thermal conductivity
and the thermal
diffusivity.
1.25
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.65
1.70
0.00 1.00 2.00 3.00 4.00 5.00 6.00
Thermaldiffusivity(m2/s*10-6)
Depth (m)CALM PAPAGAL
2.50
2.70
2.90
3.10
3.30
3.50
3.70
0.00 1.00 2.00 3.00 4.00 5.00 6.00
Thermalconductivity(W/m.K)
Depth (m)CALM PAPAGAL
THERMAL CONDUCTIVITY AND THERMAL
DIFFUSIVITY MESUREMENTS
There are being made measurements on the cores on the laboratory
of the thermal conductivity and thermal diffusivity that allows to
interpreted thermal transfer and heat flux phenomena on soils and
rocks of the area. The measurements of the thermal conductivity
and the thermal diffusivity were made in three orthogonal
directions (a, b, and c), as shown in Figure 2, with cores dry. The
determination of the cores (figure 4) from the two boreholes was
made using a TCS Lippmann & Rauen GbR equipment.
RESULTS AND ANALYSYS:
On the Table 1 are the values of the thermal conductivity, the thermal
diffusivity, and the heat production for cores obtained in the boreholes
drilled in January, 2008, in the CALM site (Figure 1) and the
PAPAGAL site (Figure 1). The variations on thermal conductivity and
thermal difuvivity according to the cores are shown on figure 4 and the
average according to depth are shown on figure 5. Table 1 also shows
the values of the heat production for the two boreholes. A SILENA
gamma-ray spectrometer was used to determine the contents in
uranium, thorium and potassium from bits of the cores from the two
boreholes. For each borehole those values are presented as well as the
heat production values which are 1.30 µW/m3 for the borehole in the
CALM site and 0.70 µW/m3 for the borehole in the PAPAGAL site.
CONCLUSIONS
The highest values of thermal conductivity were measured in the cores from the PAPAGAL site; the CALM
site has the highest thermal diffusivity value and the lowest thermal conductivity value.
The results presented here are preliminary and are far from been completed. There is being made porosity
tests to calculate the thermal conductivity values for the cores with the pores filled with water and ice, which
correspond to the climatic environment of the area where the boreholes were drilled.
REFERENCE:
Schön, J. H. (1996). Physical properties of rocks: fundamentals and principals of petrophysics,
Handbook of Geophysical Exploration, Section I, Seismic Exploration, Vol. 18). Oxford, Pergamon.
ACKNOWLEDGEMENTS: The authors thank the Fundação para a Ciência e a Tecnologia for funding the
project PERMANTAR which allowed to collect the cores used in the presentation and process the data. One of
the authors (PMA) acknowledges the grant of Caixa Geral deDepósitos.
Figure 3: Average of thermal diffusivity and thermal condutivity values for the CALM and PAPAGAL sites according to
core depth.
Figure 4: Images of some cores submitted to thermal
conductivity tests and thermal diffusivity tests on TCS Lippman
& Rauen Gbr equipment .