Thermal stimulation of the deep geothermal wells: insights from the H2020- DEEPEGS project
Abstract
Enhanced/Engineered Geothermal System (EGS) generally requires well stimulation to enhance the injectivity to commercial levels. This stimulation step still constitutes a challenge to permit large-scale deployment of this renewable energy. The present work is focused on thermal stimulation, which is often underestimated, and very little investigated. However, it may constitute a key effect especially in geothermal wells, for which temperature differences between the fluid and the formation are expected (either intentionally during dedicated stimulation, or less intentionally during drilling and operations). Thermal stimulation can lead to both thermal shearing and thermal fracturing. We model both processes, respectively through analytical and numerical modelling, applied to two EGS demonstrators in the frame of the H2020-DEEPEGS project. The first demonstrator, located in Iceland, is characterized by very high rock temperature, and is likely to encounter high thermal stimulation (both by shearing and by fracturing). The second demonstrator, located in France corresponds to lower rock temperature. In spite of uncertain context (stress state, rock properties, etc.), it appears that thermal stimulation is likely to lead to the reopening of the pre-existing sealed fractures.
Domains
Applied geology
Origin : Files produced by the author(s)
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