Assessment of geothermal resources and reserves in Denmark. A contribution to the geothermal ressource and reserve estimate of the European Community

Søren Priisholm,Steen Christensen

doi:10.34194/seriec.v2.7096

Abstract

In 1979 the European Community (EC) Directorate-General for Research and Development invited the member states to look into the aspects of geothermal resource and reserve evaluation and practical implementation of the assessment exercise within the EC. From fall 1979 to fall 1981 a working group, in which Denmark was represented by E. Gosk, set-up guidelines for a description, classification, and evaluation of geothermal resources and reserves. The guidelines are basically those outlined by Muffler and Cataldi (1978), USGS Circ 790, and applied by Cataldi et al. (1978). Contractors working on geothermal energy within the EC were from 1982 involved in the assessment of geothermal resources and reserves. From Denmark the company Danish Oil and Natural Gas A/S (D.O.N.G. A/S) and the Geological Survey of Denmark (DGU) were invited to participate in the assessment. D.O.N.G. A/S was involved as the company had the concession on geothermal energy in Denmark and was making exploration drilling. DGU was involved as the survey up to that date had made the regional mapping of the reservoirs (Michelsen et al. 1981) and was involved in contract work for the EC. The contract (no. EG-B-3-005-DK(G)) between EC and DGU, 1981-1982, had the goal of investigating the reservoir properties of possible geothermal reservoir rocks. The study was terminated with the report "Geothermal Reservoirs in Denmark" (Priisholm et al. 1982). The above mentioned contract was by a First Supplementary Agreement extended to cover 1983 with the aim of making an assessment of the geothermal resources and reserves in Denmark. The work is terminated with this final report. The report is based on the general geological knowledge of the reservoir properties which are available at the survey from the previous studies and on data made available through the exploration activities of D.O.N.G. A/S. The evaluation of assessments has been carried out as a joint work where D.G.U. has contributed with the geology and reservoir data while Tage Sørensen A/S made the resource and reserve assessments.

Highlights

Project framework and objectiveIn 1979 the European Community (EC) Directorate-General for Research and Development invited the member states to look into the aspects of geothermal resource and reserve evaluation and practical implimentation of the assessment exercise within the EC.From fall 1979 to fall 1981 a working group, in which Denmark was represented by E
DGU was involved as the survey up to that date had made the regional mapping of the reservoirs (Michelsen et al 1981) and was involved in contract work for the EC
Accessible Resource Base (ARB) ARB is a theoretical estimate of the geothermal heat, that could be available with the current drilling technology

Summary

INTRODUCTION

Parametres governing the reservoir characteristics and the performance of the reservoir rocks are the sedimentary environment, diagenesis, temperature-distribution, salinity, porosity,and permeability trends with increased depth. Formation, have similar porosity/high permeability trends they differ in diagenetic history and, in certain localities, in lithology This may cause the differences in porosity gradients where the Haldager Sand has high porosities at shallow depth of burial compared to the Skagerrak Formation (Fig. 10). Skagerrak Formation In areas where the formation is situated above 2000-2500 m depth, and where the depositional environment is the braided river regime with extensive sand bodies, transmissivities may be in the order of 20 Darcymetres. An estimate of other reservoir properties can not be given for this region at the present time because of lack of sufficient data, but high transmissivities, in the order of 50 Darcymetres may be expected. Possible Reserves represents that part of IRSVE which is based only on geological evidence at the time of determination

Findings

Discussion of parametres

Conclusion and postscript