| Title | Quantification of Exploration Risks as Basis for Insurance Contracts |
|---|---|
| Authors | Rüdiger Schulz, Sandra Pester, Rüdiger Schellschmidt, Rüdiger Thomas |
| Year | 2010 |
| Conference | World Geothermal Congress |
| Keywords | Exploration risk, geological risk, probability of success (POS), hydrogeothermal energy, wells, temperature, production rate. |
| Abstract | Exploration risk concerning hydrogeothermal wells is defined as the risk of not achieving a geothermal reservoir by one (or more) well(s) in sufficient quantity or quality. The term quality can in general be interpreted as fluid composition. Component parts can appear in the fluid, which, if they exceed certain limiting values, hinder or complicate the thermal utilization. The term quantity is defined by the (thermal) power which can be achieved by one well (or more wells). Therefore, the essential parameters regarding the quantity for the exploration risk are flow rate Q and aquifer temperature T. Both parameters are decoupled und independently measurable. A geothermal well is successful, if minimum level of thermal water production (minimum flow rate) Q at maximum drawdown ∆s and minimum level of reservoir temperature T are achieved; for that the depth of the aquifer is determined as exactly as possible from seismic reflection surveys. Information about the hydraulic parameters of an aquifer can mostly be determined in a regional scale only. For the temperature prognosis, local conditions must be considered besides regional trends. Because of the small data base, the simplest way to calculate the probability of success (POS) of a project is to multiply the single POS of flow rate and temperature. Expert reports for about 40 geothermal projects in Central Europe have been written using this method. They established the basis for insurance contracts and investors’ decisions. |