Modeling of multiphase mass and heat transfer in fractured high-enthalpy geothermal systems with advanced discrete fracture methodology

Wang, Yang; Hoop, Stephan de; Voskov, Denis; Bruhn, David; Bertotti, Giovanni

doi:10.1016/j.advwatres.2021.103985

Cited by 9 publications

(5 citation statements)

References 45 publications

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“…where U p is the internal energy of fluid phase p, U r is the rock internal energy, h p is the enthalpy of phase p, κ is the thermal conduction, and T is the temperature. All governing assumptions and properties can be found in Wang et al (2020Wang et al ( , 2021.…”

Section: 𝜕𝜕 𝜕𝜕𝜕𝜕mentioning

confidence: 99%

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

Hoop

Voskov

Bertotti

et al. 2022

Water Resources Research

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Fracture networks are abundant in subsurface applications (e.g., geothermal energy production, CO2 sequestration). Fractured reservoirs often have a very complex structure, making modeling flow and transport in such networks slow and unstable. Consequently, this limits our ability to perform uncertainty quantification and increases development costs and environmental risks. This study provides an advanced methodology for simulation based on Discrete Fracture Model approach. The preprocessing framework results in a fully conformal, uniformly distributed grid for realistic 2D fracture networks at a required level of precision. The simplified geometry and topology of the resulting network are compared with input (i.e., unchanged) data to evaluate the preprocessing influence. The resulting mesh‐related parameters, such as volume distributions and orthogonality of control volume connections, are analyzed. Furthermore, changes in fluid‐flow response related to preprocessing are evaluated using a high‐enthalpy two‐phase flow geothermal simulator. The simplified topology directly improves meshing results and, consequently, the accuracy and efficiency of numerical simulation. The main novelty of this work is the introduction of an automatic preprocessing framework allowing us to simplify the fracture network down to required level of complexity and addition of a fracture aperture correction capable of handling heterogeneous aperture distributions, low connectivity fracture networks, and sealing fractures. The graph‐based framework is fully open‐source and explicitly resolves small‐angle intersections within the fracture network. A rigorous analysis of changes in the static and dynamic impact of the preprocessing algorithm demonstrates that explicit fracture representation can be computationally efficient, enabling their use in large‐scale uncertainty quantification studies.

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Section: 𝜕𝜕 𝜕𝜕𝜕𝜕mentioning

confidence: 99%

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

Hoop

Voskov

Bertotti

et al. 2022

Water Resources Research

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“…We utilized a similar DFM approach as Wang et al (2021) by using DARTS to simulate two-phase flow in a 2D reservoir model, injecting a wetting phase in a reservoir primarily saturated with a nonwetting phase. After selecting a fracture network configuration, the apertures are distributed using an empirical relationship of the mechanical closure of initially open fractures due to applied normal stress to each fracture (Barton & Bandis 1980).…”

Section: Methodsmentioning

confidence: 99%

Improved Understanding of Naturally Fractured Reservoirs Using Data Assimilation

et al. 2022

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Naturally fractured reservoirs can pose challenges for energy operations such as hydrocarbon production, CO2 storage, and geothermal energy production. Fluid flow in these reservoirs is greatly affected by fracture properties such as orientation and aperture, whose magnitude is mainly influenced by the stresses on the reservoir rocks. Simulating fractures and their behavior tends to be computationally intensive, but recent advances in Discrete Fracture Models (DFM) have successfully overcome computational complexity and allow for the explicit inclusion of discrete fractures in reservoir simulations. However, there are still challenges in dealing with uncertainties, including fracture aperture and the effect of in-situ stresses on the fracture surface and their effect on the fluid behavior. This study explores the use of data-assimilation techniques to help quantify these uncertainties. We combine a recent implementation of DFM on the Delft Advanced Research Terra Simulator (DARTS) with both ensemble and gradientbased dataassimilation methods. Our results show that data assimilation can help to understand the dynamic behavior of fluids in fractured reservoirs. Using this technique, we obtain a more accurate representation of the stresses acting on the reservoir and how they affect the fracture aperture. This information is essential for more efficient reservoir management.

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“…Fractures are the key to fluid flow, transport, and heat transfer inside natural rock masses with distinct apertures due to the complex in situ stress (confining pressure), and knowledge of these fracture apertures plays an irreplaceable role in the seepage through fractures in many subsurface engineering applications, including seawater intrusion (Sebben et al, 2015), geothermal energy exploitation (Wang et al, 2021b;Li et al, 2022), Water-Silt Inrush Hazard (Ma et al, 2022a) and urban drainage systems (García et al, 2015;Ma et al, 2022b). However, previous research has focused on the relationship between the hydraulic aperture and in situ stress, and there are no theoretical models for predicting the change in the hydraulic aperture under in situ stress.…”

Section: Introductionmentioning

confidence: 99%

Influence mechanism of confining pressure on the hydraulic aperture based on the fracture deformation constitutive law

Feng

Ma²,

Wang³

et al. 2023

Front. Earth Sci.

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The confining pressure induces the deformation of fractures with seepage through the fracture. The seepage characteristics can reflect the deformation of the hydraulic aperture. We propose theoretical models to describe the mechanism by which the confining pressure influences the hydraulic aperture based on the fracture deformation constitutive law models of Goodman, Bandis, Sun, and Rong. Hydromechanical testing data were used to validate the four types of proposed models. The experiment results reveal the confining pressure and hydraulic aperture model based on Sun’s exponential model describes the mechanism the best. The maximum hydraulic aperture closure deformation and initial hydraulic aperture go through a growth phase with a decreasing rate, and then, they enter a stability phase when the flow rate increases to 7 ml/min, while the normal stiffness of the fracture decreases to a certain value and then tends to a stable value. Flow rate decreases as confining pressure increases in a nonlinear progression, which is described by Sun’s exponential model well. We further found that in laboratory tests at various temperatures and in field tests, the confining pressure’s influence on the hydraulic aperture is highly consistent with the model based on Sun’s model. The model developed in this study describes the mechanism by which the confining pressure influences the hydraulic aperture, and it is meaningful to rock seepage engineering with in situ stress changes at different temperatures.

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Modeling of multiphase mass and heat transfer in fractured high-enthalpy geothermal systems with advanced discrete fracture methodology

Cited by 9 publications

References 45 publications

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

Improved Understanding of Naturally Fractured Reservoirs Using Data Assimilation

Influence mechanism of confining pressure on the hydraulic aperture based on the fracture deformation constitutive law

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