Appendix 2.1. Justification of unidirectional coupling
Fig. A2: Comparison of the temperature development and breakthrough times between unidirectional- and bidirectional coupled models. In general, the bidirectional coupling (i.e. the parameters $ and in Darcy’s law are temperature depend-ent) lead to increased reservoir lifetimes in homogeneous reservoir volumes, however the general trend of the modelled production temperature development does not change. Differences between unidirectional and bidirectional coupled models decreases with increasing permeability.
9.2 Conclusions and outlook
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Appendix 2.2. Scenario 1 (S1): Homogeneous reservoir models
Fig. A3: Temperature development and breakthrough times of the nine basic homogeneous reservoir volumes, depending on the permeability, porosity, and the hydraulic gradient configuration. a to i) only north- and southward directed gradients are shown. The reservoir’s permeability increases from left to right, the reservoir’s porosity from top to bottom. Arrows indicates the shortest thermal breakthrough times.
VII
Fig. A4: Effect of variable hydraulic gradient directions and height on the reservoir shape in homogeneous reservoir volumes.
Figures show the HIT for the high permeability and medium porosity model (M6) after 160 yr of heat production. The height of the hydraulic gradient increases from left to right, the applied hydraulic gradient direction is varied from N to NW in 45°
steps from top to bottom as indicated by the sketch on the right side of the figure. The injection well is placed in the north (blue dot) and the production well is placed in the south (red dot).
9.2 Conclusions and outlook
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Appendix 2.3. Scenario 2 (S2): Layered reservoir models
Fig. A5: Temperature development and breakthrough times of layered reservoir volumes depending on the sandstone per-meability, permeability contrast, and the hydraulic gradient configuration. a to I) Only north- and southward directed gradi-ents are shown. The sandstone permeability increases from left to right, the permeability contrast increases from top to bottom. Arrows indicates the shortest thermal breakthrough times.
IX Appendix 2.4. Scenario 3 (S3): Fractured reservoirs with E-W- directed anisotropy
Fig. A6: Effect of increasing E-W-directed permeability contrast on the reservoir shape in fractured reservoir volumes. Figures a to c) show the HIT for the medium porosity and medium permeability model (M5) after 20 yr of heat production. No hy-draulic gradient is applied.
9.2 Conclusions and outlook
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Appendix 2.5. Scenario 3 (S3): Fractured reservoirs with N-S- directed anisotropy
Fig. A7: Reservoir shape of fractured reservoir volumes with a N-S-directed fracture induced permeability anisotropy of 103 depending on the hydraulic gradient direction and height. If high fracture induces anisotropies are in-line to the hydraulic gradient direction, hydraulic gradients >1 mm m-1 prevent the propagation of the HIT in z-direction. In the case of high south-ward directed hydraulic gradients, the HIT reaches the production well very fast, but does not cool down the complete catch-ment area of the production well. The injection well is placed in the north (blue dot) and the production well is placed in the south (red dot).
XI Appendix 2.6. Scenario 4 (S4): Fractured and layered reservoir volumes
Fig. A8: Combined effect of layering and fracturing on the thermal development, breakthrough times, and reservoir shape.
Only north- and southward directed gradients are shown. The permeability contrast of the layered succession is 103, the permeability anisotropy of the sandstone layers is 102. From a to f) the permeability anisotropy of the claystone layers in-creases from homogeneous to a value equal to the permeability anisotropy in the sandstone layers, i.e. the fractures are nonstratabound. In the last case (f), the temperature development in the reservoir is identical to the homogeneous and anisotropic model (Fig. 7.6b). Arrows indicates the shortest thermal breakthrough times.
9.2 Conclusions and outlook
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Appendix 2.7. Scenario 5 (S5): Fault-related reservoirs
Fig. A9: Temperature development, breakthrough times, and reservoir shape of fault-related reservoir volumes acting as barrier depending on fault core permeability and hydraulic gradient configuration. The host rock properties are based on the medium permeability and medium porosity model (M5). a to c) the temperature development of the produced fluid over time for north- and southward directed hydraulic gradients. The fault core permeability increases from left to right. Arrows indicates the shortest thermal breakthrough times. d to f) the corresponding shape of the HIT after 40 yr of heat production, simulated for a hydraulic gradient of 0 mm m-1. Arrows indicates the shortest thermal breakthrough times.
XIII
Fig. A10: Temperature development, breakthrough times, and reservoir shape of fault-related reservoir volumes acting as conductor depending on damage zone permeability and hydraulic gradient configuration. The host rock properties are based on the medium permeability and medium porosity model (M5). a to c) the temperature development of the produced fluid over time for north- and southward directed hydraulic gradients. The damage zone permeability increases from left to right.
Arrows indicates the shortest thermal breakthrough times. d to f) the corresponding shape of the HIT after 40 yr of heat production, simulated for a hydraulic gradient of 0 mm m-1.
9.2 Conclusions and outlook
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Fig. A11: Temperature development, breakthrough times, and reservoir shape of fault-related reservoir volumes acting as combined conduit-barrier system depending on fault core permeability and hydraulic gradient configuration. The host rock properties are based on the medium permeability and medium porosity model (M5). a to c) the temperature development of the produced fluid over time for north- and southward directed hydraulic gradients. The fault core permeability decreases from left to right. Arrows indicates the shortest thermal breakthrough times. d to e) the corresponding shape of the HIT after 40 yr of heat production, simulated for a hydraulic gradient of 0 mm m-1.