Publication Date:
2020-05-19
Description:
Developing ow paths or expanding existing pathways in deep geological strata is generally referred to as "stimulation". To extract heat from geothermal reservoirs, stimulation treatments are carried out by injecting water at high pressure into the formation (hydraulic stimulation), by dissolution of certain mineral components, mostly carbonates, thus increasing the hydraulic pathways (chemical stimulation), or by cooling of the rock to induce tensile stresses which helps the fracture expansion (thermal stimulation). The achieved factor of productivity increase by conventional stimulation treatments is reported to be between 1.3 and 25. In petrolium industry a significant decline of the production increase occurs already during the first year after stimulation. The time to refracturing is typically 4 to 7 years. It is not clear whether these values are also appropriate for geothermal applications. The sustainability of the increase in permeability due to thermal stimulation depends on the situation: for an injection well the increase remains for few years. For production wells, the longevity of the stimulation depends on the self-propping ability of the rock. After reviewing the current situation in the field of deep geothermal energy in Europe, dierent stimulation techniques are discussed. Furthermore, case studies of stimulation treatments in deep geothermal reservoirs are presented. In the subsequent chapters the authors present the methods of stimulation treatment in deep geothermal wells to show the increase of productivity, to explain the potential benefits and risks and estimate the economic performance.
Language:
English
Type:
info:eu-repo/semantics/report
Format:
application/pdf
