Table 1 Reservoir rock and fracture properties.

Reservoir rock density, ρ

2700 kg/m³

Reservoir rock porosity, ϕ

0.001–0.03

Thermal conductivity of rock, λ_s

3.0 W/(m K)

Specific heat capacity of rock, C_s

900 J/(kg K)

thermal expansion coefficient of rock, α_T

4e−7 1/K

Rock matrix permeability, k

1e−15 m²

Elastic modulus of rock, E

50 GPa

Poisson’s ratio of rock, ν

0.21

Rock cohesion, C

30 MPa

Fracture cohesion, C_f

0.5 MPa

Angle of internal friction of rock, φ

45°

Friction angle of fracture, φ_f

40°

Biot coefficient, α

0.9

Fracture aperture, d_f

0.1–1 mm

Fracture length, L_f

50 m–150 m

Injection mass rate, Q_inj

40 kg/s

Injection fluid temperature, T_inj

20 ℃