Dynamic analysis of heat extraction rate by supercritical carbon dioxide in fractured rock mass based on a thermal-hydraulic-mechanics coupled model

Wang, Chunguang; Shi, Xingkai; Zhang, Wei; Elsworth, D.; Cui, Guanglei; Liu, Shuqing; Wang, Hongxu; Song, Weiqiang; Hu, Songtao; Zheng, Peng

doi:10.1016/j.ijmst.2021.12.004

Cited by 37 publications

(6 citation statements)

References 63 publications

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“…Furthermore, the impact of thermal radiation on system heat transfer is not factored in. In summary, the governing equation for the overall temperature field of EGS can be expressed as 29,30 :…”

Section: Governing Equations Of Co 2 -Egs Modelmentioning

confidence: 99%

“…The heat transfer coefficient comes from literature. 33,34 Previous studies have shown that the porosity φ of the CO 2 -EGS reservoir is influenced by the flow field, temperature field, and stress field, and its dynamic evolution law can be represented as 35 :…”

Section: Governing Equations Of Co 2 -Egs Modelmentioning

confidence: 99%

“…Furthermore, the impact of thermal radiation on system heat transfer is not factored in. In summary, the governing equation for the overall temperature field of EGS can be expressed as 29,30 :

\begin{array}{c}\frac{\partial \left({\rho }_{{\mathrm{CO}}_{2}}{c}_{{\mathrm{CO}}_{2}}\varphi T\right)}{\partial t}+{\rho }_{s}{c}_{s}\frac{\partial T}{\partial t}=-\nabla \cdot \left({\rho }_{{\mathrm{CO}}_{2}}{c}_{{\mathrm{CO}}_{2}}VT\right)+\nabla \cdot ({\lambda }_{{\mathrm{CO}}_{2}}\varphi \nabla T)+{\lambda }_{s}\nabla \cdot (\nabla T)+T{\alpha }_{T}K\frac{\partial {\varepsilon }_{V}}{\partial t}+{Q}_{T},\\ \end{array}

where Q T = Q s + Q CO2 .…”

Section: The Theory Of Co2‐egs Considering Reservoir Changesmentioning

confidence: 99%

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Numerical study of enhanced geothermal systems with supercritical CO₂ injection considering reservoir changes

Xiao,

Li,

Gong

et al. 2024

Energy Science & Engineering

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The injection of supercritical CO2 (ScCO2) into the enhanced geothermal systems (EGS) is a highly intricate thermohydromechanical (THM) coupled process. To improve the realism and accuracy of simulating convective heat transfer characteristics in CO2‐EGS, a coupled model based on discrete fracture network (DFN) theory is established. In this model, the dynamic evolution laws of reservoir porosity and permeability, as well as the nonlinear variations of thermophysical parameters for ScCO2 under the influences of temperature and pressure are considered. The validity of the numerical results was confirmed through a comparative analysis with the analytical solution. The result shows that the ScCO2 can rapidly extracts heat from both the fractures and the adjacent rock matrix. The heat of the rock matrix far away from the fractures cannot be compensated to the fractures immediately, resulting in the high temperature peak effect of the local rock matrix. The injection of ScCO2 can increase the porosity and permeability of reservoir, which is induced by the weakened thermal expansion effect of rock. The alteration of reservoir porosity and permeability also leads to the change of the flow characteristics of ScCO2. Additionally, the thermal parameters of ScCO2 changes with the temperature and pressure conditions of the reservoir. The change of flow rate and heat extraction rate of ScCO2 in EGS is dominated by the decrease of density, specific heat capacity, porosity, permeability, and thermal conductivity.

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Section: Governing Equations Of Co 2 -Egs Modelmentioning

confidence: 99%

Section: Governing Equations Of Co 2 -Egs Modelmentioning

confidence: 99%

“…Furthermore, the impact of thermal radiation on system heat transfer is not factored in. In summary, the governing equation for the overall temperature field of EGS can be expressed as 29,30 :

\begin{array}{c}\frac{\partial \left({\rho }_{{\mathrm{CO}}_{2}}{c}_{{\mathrm{CO}}_{2}}\varphi T\right)}{\partial t}+{\rho }_{s}{c}_{s}\frac{\partial T}{\partial t}=-\nabla \cdot \left({\rho }_{{\mathrm{CO}}_{2}}{c}_{{\mathrm{CO}}_{2}}VT\right)+\nabla \cdot ({\lambda }_{{\mathrm{CO}}_{2}}\varphi \nabla T)+{\lambda }_{s}\nabla \cdot (\nabla T)+T{\alpha }_{T}K\frac{\partial {\varepsilon }_{V}}{\partial t}+{Q}_{T},\\ \end{array}

where Q T = Q s + Q CO2 .…”

Section: The Theory Of Co2‐egs Considering Reservoir Changesmentioning

confidence: 99%

See 1 more Smart Citation

Numerical study of enhanced geothermal systems with supercritical CO₂ injection considering reservoir changes

Xiao,

Li,

Gong

et al. 2024

Energy Science & Engineering

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“…The mass conservation for flow in fractures is described by Darcy’s law defined below: − where m f is the mass of gas in the fracture, Q s is the total volumetric flux through the fracture, which is equal to the integral of local fluxes through the outlet boundary of the model, u f is the flow velocity in the fracture, p f is the gas pressure in the fracture, k f is the permeability of the fracture, and ρ f is the fluid density in the fracture.…”

Section: Mathematical Model and Numerical Modelmentioning

confidence: 99%

Analysis of the Upper and Lower Boundaries of Permeability Evolution during Shale Rock Shear Deformation

Sun

Chen

Zhu³

et al. 2022

Energy Fuels

Self Cite

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Understanding the evolution of permeability during rock shear displacement plays an important role in many geosciences and geo-engineering, such as shale gas exploitation. In previous studies, permeability data were obtained under different experimental conditions with varied in situ stress environments, fracture apertures, or loading stresses. However, the mechanisms controlling the permeability evolution during the shear process have not been well explained. In this study, two special conditions, fractures with constant stiffness (CS) and constant volume (CV), are proposed to define the upper and lower boundaries of permeability evolution. An inverted "L-shaped" model containing a matrix and fracture was established to investigate the permeability evolution and internal morphological changes in the fractures. The impacts of the initial fracture aperture and normal stress in the shear process are discussed together with the apparent fracture aperture, effective flow area, and pore throat radius. Under the CS condition, the self-supporting effect produced by the contact between the upper and lower fracture surfaces plays a dominant role in changing the permeability, and three stages of permeability evolution with shear displacement are observed: rapid increase, slow increase, and decrease. Under CV conditions, the submergence effect of the fracture closed the effective flow channels, thereby reducing the permeability in three stages: rapid decrease, slow decrease, and recovery. The model results show that both a smaller initial fracture aperture or a greater normal stress lead to a greater variation in the permeability and the roughness of fracture surface determines the permeability evolution range. The new model was applied to generate a series of shale permeability evolution boundaries under different limit conditions. These boundaries are consistent with experimental observations reported in other literatures. This work provides new insights into the permeability evolution of rock strata under shear action.

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“…Liu et al 15 established a new numerical model to simulate the supercritical CO 2 fracturing; the numerical model couples an amorphous flow model based on the pore-scale network method and a solid model based on the finite element method with cohesive zone cells, and the amorphous flow model reproduces the two-phase flow by considering viscous and capillary forces on the pore scale. Wang et al 16 considered the deformation of the fractured reservoirs, the non-Darcy seepage and the thermophysical change of supercritical CO 2 , and established the thermal−hydraulic−mechanical (THM) coupled model, and the validity of the model was confirmed by matching the model temperature distribution with the published data. Peng et al 17 simulated supercritical CO 2 fracturing based on the cohesive particles model to study the effect of the original natural microfractures on the distribution of the induced fracture network.…”

Section: Introductionmentioning

confidence: 99%

Influence of Supercritical CO₂ Fracturing Mode on the Fracture Morphology and Propagation Characteristics of Coal

Sun,

Zhao,

Wang

et al. 2024

Energy Fuels

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To investigate the fracture morphology and expansion characteristics of coal seams by different fracturing methods using supercritical CO 2 , we carried out supercritical CO 2 fracturing of coal bodies and analyzed the temporal and spatial evolution characteristics of coal body fractures based on the pressure−time curves, otoacoustic emission events, and CT structural characterization of coal samples. The following conclusions were made: (1) Tiny fluctuations were observed in the time−pressure curves before fracture, which indicated that the microfracture appeared in the specimen; when a larger range of fissures was produced in the coal sample, the pressure dropped rapidly. (2) The acoustic emission events indicated that the fracturing by supercritical CO 2 under the incremental temperature and incremental pressure injection method was stronger than that under the continuous injection method. (3) Compared with hydraulic fracturing, supercritical CO 2 fracturing showed smaller fracture tip lag lengths, smaller intruding pore throat widths, and more complex phase changes in fracture extension.

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Dynamic analysis of heat extraction rate by supercritical carbon dioxide in fractured rock mass based on a thermal-hydraulic-mechanics coupled model

Cited by 37 publications

References 63 publications

Numerical study of enhanced geothermal systems with supercritical CO₂ injection considering reservoir changes

Numerical study of enhanced geothermal systems with supercritical CO₂ injection considering reservoir changes

Analysis of the Upper and Lower Boundaries of Permeability Evolution during Shale Rock Shear Deformation

Influence of Supercritical CO₂ Fracturing Mode on the Fracture Morphology and Propagation Characteristics of Coal

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Dynamic analysis of heat extraction rate by supercritical carbon dioxide in fractured rock mass based on a thermal-hydraulic-mechanics coupled model

Cited by 37 publications

References 63 publications

Numerical study of enhanced geothermal systems with supercritical CO2 injection considering reservoir changes

Numerical study of enhanced geothermal systems with supercritical CO2 injection considering reservoir changes

Analysis of the Upper and Lower Boundaries of Permeability Evolution during Shale Rock Shear Deformation

Influence of Supercritical CO2 Fracturing Mode on the Fracture Morphology and Propagation Characteristics of Coal

Contact Info

Product

Resources

About

Numerical study of enhanced geothermal systems with supercritical CO₂ injection considering reservoir changes

Numerical study of enhanced geothermal systems with supercritical CO₂ injection considering reservoir changes

Influence of Supercritical CO₂ Fracturing Mode on the Fracture Morphology and Propagation Characteristics of Coal