Page 300 - Geothermal Energy Systems Exploration, Development, and Utilization
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276 5 Geothermal Reservoir Simulation
The model couples mechanical deformation and alteration of fracture parameters
with state of the art fluid parameter functions dependent on pressure, temperature,
and salinity for heat capacity, conductivity, viscosity, and density. The effects of
the coupling on the reservoir productivity characteristics and potential reservoir
damage were investigated to assist in the identification of optimal heat recovery
schemes for the long-term economical operation. Preferential flow paths and
hydraulic short cuts dependent on the geomechanical and thermal stress release
behavior were predicted for overexploitation.
5.6.2.2 Development of Preferential Flow Paths due to Positive Feedback Loops in
Coupled Processes and Potential Reservoir Damage
The effect of the coupling of the processes investigated, led to systematic and
localized changes in the flow and transport characteristics, systematic in terms
of the progressive development of the phenomena and localized in terms of the
impact at specific locations. This led to the development of preferential flow paths
(Hicks et al., 1996; Su et al., 2001; Zheng and Gorelick, 2002) and geometrical
Flow Plan view of
dipole flow paths
Injection Extraction
Vertical slice
3800
Depth (m) 4000
4200
−400 −200 0 +200 +400
x direction (m)
0 4 8 12 16 20 23
Temperature difference (°c)
Figure 5.21 Hydromechanical coupling, the reservoir is
more permeable under the lower stress conditions at the
top of the reservoir than the higher stress conditions at the
base of the reservoir. (Please find a color version of this
figure on the color plates.)