A three-dimensional coupled thermo-hydro-mechanical model for deformable fractured geothermal systems

Salimzadeh, Saeed; Paluszny, Adriana; Nick, Hamidreza M.; Zimmerman, Robert W.

doi:10.1016/j.geothermics.2017.09.012

Cited by 176 publications

(62 citation statements)

References 33 publications

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“…As seen from these equations, fluid flow, heat transfer, and the mechanic responses of the reservoir systems are coupled with each other. Its solution usually requires a coupled modeling approach, thus, coupled THM analysis is important in geomechanical modeling [25]. Figure 1 shows a schematic of the geomechanical modeling framework, which contains a coupled THM simulation and history matching for calibration of the numerical model.…”

Section: General Framework Of Geomechanical Modelingmentioning

confidence: 99%

Fiber Optic Sensing for Geomechanical Monitoring: (2)- Distributed Strain Measurements at a Pumping Test and Geomechanical Modeling of Deformation of Reservoir Rocks

2019

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In this study distributed fiber optic sensing has been used to measure strain along a vertical well of a depth of 300 m during a pumping test. The observed strain data has been used in geomechanical simulation, in which a combined analytical and numerical approach was applied in providing scaled-up formation properties. The outcomes of the field test have demonstrated the practical use of distributed fiber optic strain sensing for monitoring reservoir formation responses at different regions of sandstone–mudstone alternations along a continuous trajectory. It also demonstrated that sensitive and scaled rock properties, including the equivalent permeability and pore compressibility, can be well constrained by the combined use of water head and distributed strain data. In comparison with the conventional methods, fiber optic strain monitoring enables a lower number of short-term tests to be designed to calibrate the parameters used to model the rock properties. The obtained parameters can be directly used in long-term geomechanical simulation of deformation of reservoir rocks due to fluid injection or production at the CO2 storage and oil and gas fields.

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Section: General Framework Of Geomechanical Modelingmentioning

confidence: 99%

Fiber Optic Sensing for Geomechanical Monitoring: (2)- Distributed Strain Measurements at a Pumping Test and Geomechanical Modeling of Deformation of Reservoir Rocks

2019

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“…Consequently, a doublet EGS model is presented in this paper based on the above geological survey and numerical model (as shown in Figure ). In EGS reservoir, the fracture networks are critical to the whole heat extraction cycle . In this system, the fault is more permeable than the fracture, and there is no doubt that the fault‐fracture system can enhance the connectivity between the injection well and production well.…”

Section: Description Of the Numerical Modelmentioning

confidence: 99%

Production capacity and mining plan optimization of fault/fracture‐controlled EGS model in Gonghe Basin

Zhang

Xie

Zhang

2019

Energy Science & Engineering

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Taking full advantage of geological conditions is beneficial to reduce the development cost and enhance the exploit of geothermal energy in the Gonghe Basin. In this paper, a thermal-hydraulic coupled model is put forward to study the heat extraction for Gonghe Basin based on local thermal nonequilibrium theory considering the natural fault. An excellent heat recovery system and reasonable combination of parameters are the premise of sustainable geothermal development. Two doublet systems are introduced to investigate the efficiency of the fault/fracture-controlled EGS model.A comparative analysis is performed from the aspect of production temperature, heat extraction ratio, flow impedance, injection pressure, thermal power, and electric power. Key parameters (injection rate, injection temperature, production pressure, number of fractures, vertical interval between the two storages, and the storage permeability) are discussed. The results show that the fault-fracture-controlled doublet model is more suitable for EGS to heat transfer than the common doublet model. The doublet model at a depth of 3300-3800 m has a temperature gradient of 0.04°C/m.For fault-fracture-controlled EGS model, the optimal values are 50 kg/s, 15 MPa, 60°C, 310 m, 4 × 10 −14 m 2 , and two for injection rate, production pressure and injection temperature, vertical interval, storage permeability, and fracture number, respectively. The best well pattern layout method for the Gonghe Basin is one injection well and two production wells. The production temperature varies from 196.8°C to 192.7°C when the heat extraction ratio is 0.13 at the end of the operation. Thus, the fault-fracture-controlled EGS model can provide a mining method and advance the development of geothermal energy for the Gonghe Basin in the future. K E Y W O R D Senhanced geothermal system, fault/fracture-controlled model, local thermal nonequilibrium, parameter optimization | 2967 ZHANG et Al.

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“…Suggested universal relationships between flow and stiffness (Petrovitch et al, 2014;Pyrak-Nolte & Nolte, 2016) treat fractures as isotropic void spaces. Fracture transmissivities can also be defined as a mean or locally varying transmissivity field (De Dreuzy et al, 2012;Hamzehpour et al, 2009) or as a function of locally varying apertures resulting from the deformation of the rock mass in response to local or remote stresses (Salimzadeh et al, 2018). Therefore, the permeability of a geometrically isotropic fracture network may vary as a function of in situ stresses.…”

Section: 1029/2018wr023189mentioning

confidence: 99%

Relationship Between the Orientation of Maximum Permeability and Intermediate Principal Stress in Fractured Rocks

Lang

Paluszny

Nejati

et al. 2018

Water Resources Research

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Flow and transport properties of fractured rock masses are a function of geometrical structures across many scales. These structures result from physical processes and states and are highly anisotropic in nature. Fracture surfaces often tend to be shifted with respect to each other, which is generally a result of stress‐induced displacements. This shift controls the fracture's transmissivity through the pore space that forms from the created mismatch between the surfaces. This transmissivity is anisotropic and greater in the direction perpendicular to the displacement. A contact mechanics‐based, first‐principle numerical approach is developed to investigate the effects that this shear‐induced transmissivity anisotropy has on the overall permeability of a fractured rock mass. Deformation of the rock and contact between fracture surfaces is computed in three dimensions at two scales. At the rock mass scale, fractures are treated as planar discontinuities along which displacements and tractions are resolved. Contact between the individual rough fracture surfaces is solved for each fracture at the small scale to find the stiffness and transmissivity that result from shear‐induced dilation and elastic compression. Results show that, given isotropic fracture networks, the direction of maximum permeability of a fractured rock mass tends to be aligned with the direction of the intermediate principal stress. This reflects the fact that fractures have the most pronounced slip in the plane of the maximum and minimum principal stresses, and for individual fractures transmissivity is most pronounced in the direction perpendicular to this slip.

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A three-dimensional coupled thermo-hydro-mechanical model for deformable fractured geothermal systems

Cited by 176 publications

References 33 publications

Fiber Optic Sensing for Geomechanical Monitoring: (2)- Distributed Strain Measurements at a Pumping Test and Geomechanical Modeling of Deformation of Reservoir Rocks

Fiber Optic Sensing for Geomechanical Monitoring: (2)- Distributed Strain Measurements at a Pumping Test and Geomechanical Modeling of Deformation of Reservoir Rocks

Production capacity and mining plan optimization of fault/fracture‐controlled EGS model in Gonghe Basin

Relationship Between the Orientation of Maximum Permeability and Intermediate Principal Stress in Fractured Rocks

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