Soultz granite - saline water interactions at 175-200°C and 10-50 bar: experimental and thermo-kinetic modeling approaches

摘要

Laboratory and in-situ (at depths between 2000 and 5000 m) water - granite interactions phenomena were studied in the framework of the development of the future European Hot Dry Rock (HDR) geother-mal exchanger at Soultz-sous-Forets (Alsace, France). The target reservoir consists of a fractured granite with high saline solutions (～ 100 g/1, ～ 200°C). Experiments of saline water (1, 10, 25 g/1) - granite interactions were achieved in dynamic systems. On the other hand, thermo-kinetic modeling results were compared to the laboratory experimental observations. A good compromise was obtained assuming local chemical equilibrium between the percolating fluid and zeolites, smectites, illite, calcite and goethite. This agreement was obtained when measured N_2-BET specific surface was reduced by 0.001 to 35%. This result confirms the systematic discrepancy between operational kinetic constants and that determined in very constrained and simplified systems. Hence, the difficulty of precisely determining water - minerals exchange surface area and the misunderstood surface reaction mechanisms limits greatly the predictive capacity of thermo-kinetic modeling software.