Geothermal 3-D
Modell for the City of Hamburg and surrounding areas
Temperature prediction
down to 6 km Depth
By order of the geological survey of the
city of Hamburg we developed a numerical 3-D model to evaluate the
geothermal potential of the subsurface. The geothermal model is based
on a geological 3-D model which was provided by the geological survey
of Schleswig-Holstein. The objective was to simulate the undisturbed
temperature field affected by the tectonic setting.
The geological model
represents all important lithological units down to the Rotliegend
including the existing salt structures. The corresponding regional
numerical model extends over an area of 35 km x 28 km down to a depth
of 6 km. For a reliable temperature prediction it was necessary to
define the thermal properties precisely, in particular thermal
conductivity. For this purpose we compiled existing borehole data, and
in combination with other data from the North German basin we were
able to assign representative values of thermal properties to each
geological unit. Undisturbed temperature logs of deep boreholes in the
regarded area could be used for model calibration. These data agree
well with the steady-state simulations, using the derived thermal
properties. The model results show the significant influence of the
salt structures due to their comparable high thermal conductivity: at
reservoir depths of approximately 3.5 km horizontal temperature
variations of more than 35 K are possible.
Thus, this regional model
allows to reliably predict temperatures for any target area or
reservoir within the model domain. The model provides the basis for
further reservoir simulations to predict the long term production
behaviour of deep installation such as a geothermal doublet.
Model results can be
requested by Behörde für Stadtentwicklung und Umwelt (U), Geologisches
Landesamt Hamburg