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Modelling the geochemical effects of acid treatments and comparison with field observations at soultz-sous-forets geothermal site. |
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Acid treatments have been successfully applied in many cases to increase or to
recover geothermal wells production rates to commercial levels. These stimulation
techniques were originally developed to address similar problems in oil and gas
production wells. The applicability of these stimulation techniques to a high
temperature, naturally-fractured reservoir is less well known. High temperatures
increase the acid-rock reaction rate. The development of Enhanced Geothermal
Systems (EGS) depends on the creation of permeable and connected fractures. Acid
stimulation jobs intend to clean(pre-existing) fractures by dissolving filling
materials (secondary minerals or drilling muds) and mobilizing them for an
efficient removal by flow transport. Recent acid treatments were performed on the
EGS wells at Soultz-sous-Forêts (France). This 200°C and 5-km deep granitic
reservoir contains fractures partially filled with secondary carbonates (calcite
and dolomite). In order to dissolve these carbonates and to enhance the
productivity around the wells, each of the three boreholes (GPK2, 3 and 4) were
successively treated with various amounts of hydrochloric acid. The FRACHEM code, a
Thermo-Hydraulic-Chemical coupled code, has been developed especially to forecast
the evolution of the Soultz reservoir. Reactive transport modelling with FRACHEM
code has been used to simulate acid injection and its impact on brine-rock
interactions. Comparisons between FRACHEM simulations and field observations will
be tested to forecast the impact of acid treatments on reservoir properties. Our
goal is to simulate the effect of acid injection on permeability evolution in
fractures at pressure and temperature conditions of the Soultz geothermal site.
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Id: |
18 |
Place: |
Kartause Ittingen, Switzerland CH-8532 Warth TG
www.kartause.ch |
Starting date: |
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Duration: |
15' |
Primary Authors: |
PORTIER, Sandrine (CREGE (c/o CHYN, Neuchâtel, Switzerland)) |
Co-Authors: |
VUATAZ, François-David (CREGE (c/o CHYN, Neuchâtel, Switzerland)) ANDRE, Laurent (BRGM) |
Presenters: |
PORTIER, Sandrine |
Material: |
Paper Slides |
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