Numerical investigation of electricity generation potential from fractured granite reservoir through a single vertical well at Yangbajing geothermal field

Orthogonal Test Analysis on Conditions Affecting Electricity Generation Performance of an Enhanced Geothermal System at Yangbajing Geothermal Field

“…Because there is only very slight conductive heat transfer between the permeable reservoir and the impermeable cap and base rock, this conductive heat transfer can be neglected [6][7][8][9]19]. As shown in Figure 3, after these simplifications are implemented, the simulated domain is within 0~500 m in the x direction, and is within −1350~−950 m in the z direction.…”

“…The initial pressure at the injection well at z = −1325 m is P wo = 11.35 MPa. If the safety factor f is f = 1.32 [4][5][6][7][8][9], the maximum available pressure P max at the injection well is P max = f ·P wo = 14.98 MPa. During the whole 20 years of heat production, the injection pressure P inj must be lower than P max = f ·P wo = 14.98 MPa.…”

“…This pressure range is computed according to the relationship between pressure P (MPa) and depth z (m) as P = −0.0089z − 0.4444 (MPa), which is also indicated in [25]. More information about the Yangbajing geothermal field can been found in reference [6][7][8][9]19,24,25]. 0.0089 0.4444 (MPa) P z = − − , which is also indicated in [25].…”

“…Zeng et al employed the EPM method to investigate the electricity generation potential through a single horizontal well [6], multiple vertical wells [7], multiple horizontal wells [8], and a single vertical well [9] at Yangbajing geothermal field, and the results show that the horizontal well system has better electricity generation performance under the same conditions. Based on thermodynamic non-equilibrium assumption, Jiang et al employed the EPM method to develop a three-dimensional transient model for an EGS subsurface hydraulic-thermal process and used the novel model to analyze the performance characteristics of the heat production of EGS [10,11].…”

“…Therefore, we can simultaneously neglect the effects of rock deformation and chemical reaction and just assume that after stimulation the fracture aperture and spacing remain unchanged over the heat production lifetime. Previous studies prove that the effect of reservoir heterogeneities on the production performance of EGS is obvious and complicated; for the purpose of simplification, in this work, only the homogeneous reservoir is considered, and the detailed content on the reservoir heterogeneities will be addressed in future work [4][5][6][7][8][9]19,22].…”