Assessment of sedimentary geothermal aquifer parameters in Denmark with focus on transmissivity.

Abstract

The latest assessment of the geothermal resources in Denmark concluded that the Danish subsurface contains huge geothermal resources. However, exploration and exploitation of geothermal energy involves large investments in wells and surface installations, and therefore, utilization of geothermal energy in Denmark today must – in order to succeed – both minimise the risk of not finding suitable subsurface reservoirs and insuring that well design, economics, development and operating of the geothermal plants are optimised. During the recent years it has become clear that initial assessments of the subsurface geothermal potential are best determined from a number of geological parameters. These parameters are all dependent on geological processes and are presently being investigated and mapped by geological and geophysical methods, which are comparable to maturation of hydrocarbon prospects. A method compiling and quantifying all available data and information is presented. The method addresses the variation in data quality in order to assess the most important geological parameters using all essential and available log and seismic analyses and integrating it with conventional core and production test analyses. This evaluation forms the basis of analysing and comparing transmissivities calculated from different assessment methods, e.g. interpretation of log data combined with porosity-permeability relations against flow models and interpretation of well test data (production tests). A possible relation between logderived transmissivity and a transmissivity derived from production test data will be discussed.