Quantifying geothermal exploration risks: optimising the method on the basis of geoscientific data and information.
The exploration risk of a geothermal well is the risk of developing a geothermal reservoir by drilling one or more wells and establishing that the reservoir is either of inadequate quantity or quality (composition of the thermal water). A crucial factor for the heat capacity of a geothermal plant is the quantity, which depends on the production rates achievable using reasonable technical input, and the temperature of the thermal water. A simple method of estimating the probability of a project being successful involves assessing the individual risks for temperature and flow rate. The product of the separate probabilities can be used to determine the overall probability, and therefore the chances of success of the project with respect to the economic specifications stipulated by the operator. LIAG has used this method on behalf of insurance companies and investors in recent years to produce 50 independent assessments evaluating the exploration risks of the planned geothermal projects.
As part of the GEOFÜND project, the method was evaluated by initially comparing the data with already realised projects and the success probabilities forecast in the independent assessments. This is to be followed up by investigating whether the previous method can be improved by incorporating geostatic processes such as kriging and the integration of other geoscientific information, and whether this can be extrapolated to other regions and application technologies. Moreover, the possibilities of incorporating the seismic exploration results and other geoscientific information to estimate the exploration risk will also be examined.
The work carried out by LIAG to evaluate and further develop a method to estimate the exploration risk is part of the joint project "GEOFÜND − Characterisation and further development of integrative investigation methods to quantify exploration risks". GEOFÜND means to further develop methodological approaches to evaluate the exploration risks of geothermal projects and to improve it by incorporating modern mathematical methods to produce enhanced findings on the geological characterisation of underground formations.