New Concept for the Application of Outcrop Analogue Data for Geothermal Probability of Success (POS) Studies - Examples of Projects in the Northern Upper Rhine Graben (Germany)

Abstract

Probability of success (POS) studies for deep geothermal projects are usually based on hydraulic test data of geothermal wells located in the same reservoir system in a comparable regional setting. Based on this fact prospective risk insurances (Fündigkeitsinsurance), which are often an important economic prerequisite for geothermal power projects in Germany, are not available for geothermal greenfield projects, where almost no drilling or hydraulic information of the reservoir are available. To bypass this problem, which is partly responsible for the slow progress of the development of geothermal power production in Germany, we propose an alternative form of POS studies based on suitable outcrop analogue data. Based on a vast data base of thermophysical rock properties ( more than 9,000 measurements) and hydraulic test data sets ( more than 1,500 tests) sampled east and west on the Graben shoulders, borehole temperature measurements ( more than 2,500 measurements) and a 3D geological model, a detailed geothermal model of the northern Upper Rhine Graben was established. This regional model, which incorporates important fault systems within the Graben and their influence on the depth and temperature dependent geothermal and hydraulic properties of different reservoir formations, is used for a local calculation of the POS. We demonstrate the usability of this probabilistic model to determine the POS for different actual project locations within the northern Upper Rhine Graben and discuss statistic uncertainties and inferred explorations risks for different locations.