Comparison of multi-field coupling numerical simulation in hot dry rock thermal exploitation of enhanced geothermal systems

Chen, Shichao; Ding, Bin; Gong, Liang; Huang, Zhaoqin; Yu, Bo; Sun, Shuyu

doi:10.26804/ager.2019.04.07

Cited by 17 publications

(4 citation statements)

References 21 publications

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“…e fractures are assumed to be equipotential; thus, several points F j on the fracture surface can be selected as the reference points, and these points have the same pressure P F . Applying equation (15) on every reference point forms a linear equation system:…”

Section: Modeling Of Flow In Fractured Reservoirs Considering Matrix ...mentioning

confidence: 99%

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Coupled Geomechanics and Flow Modeling of Fractured Reservoirs considering Matrix Permeability Anisotropy

2022

Geofluids

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The effect of geomechanics is crucial in the modeling of fractured reservoirs since fractures can be more stress-sensitive than the rock matrix. In fractured reservoirs, the microscale fractures are often homogenized into the matrix continuum leading to matrix permeability anisotropy. The embedded discrete fracture model (EDFM) is becoming increasingly popular for numerical simulation of fractured reservoirs and has been successfully employed in the simulation of coupled geomechanics and flow systems. However, the anisotropic permeability of matrix cannot be considered in traditional EDFM. An approach of coupled geomechanics and flow modeling is proposed for fractured reservoirs considering anisotropic matrix permeability. In order to calculate the fluid exchange between fractures and rock matrix in an anisotropic formation, an integrally embedded discrete fracture model (IEDFM) is used. The geomechanics model of the proposed approach uses an equivalent continuum approach, which introduces an equivalent material to represent the overall deformation of the fractured rock under normal and shear stresses. The constitutive relations of the equivalent continuum are derived rigorously from stress-strain analysis, where the stress-dependent moduli of natural fractures are included. The coupled geomechanics and flow system is solved using the fixed-stress split iterative coupling strategy with the dynamic hydraulic parameters of matrix and fractures updated separately. Several examples are performed to demonstrate the applicability of the proposed approach for modeling the coupled geomechanics and flow system in fractured reservoirs considering anisotropic permeability. The effect of anisotropy is investigated, which indicates that the dynamic behavior of a fracture is highly orientation-related due to initial stress anisotropy and matrix permeability anisotropy. Simulations also show that the anisotropic matrix permeability affects the compaction in the reservoir domain, which reflects on the performance of production.

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Section: Modeling Of Flow In Fractured Reservoirs Considering Matrix ...mentioning

confidence: 99%

“…en, Wittke [8] rigorously derived the constitutive model for a fractured rock using the concept of equivalent continuum. Later, series of attempts to simulate coupled geomechanics and flow problems in fractured reservoirs using the dual continuum concept and the dual porosity poroelastic theory are performed [9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Coupled Geomechanics and Flow Modeling of Fractured Reservoirs considering Matrix Permeability Anisotropy

2022

Geofluids

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“…Through the establishment of this temperature distribution, when the steam chamber drain zone reaches a certain observation position, the position of the steam chamber's front edge and its temperature can be obtained in real-time to predict the width of the drain zone and the movement speed of the steam chamber [2,[23][24][25]. Furthermore, by incorporating the geological parameters of Well Z into the temperature equation at the edge of the steam chamber, a temperature distribution map of the oil drainage zone can be obtained.…”

Section: Temperature Distribution At the Edge Of The Steammentioning

confidence: 99%

Expansion Velocity Model of Steam-Assisted Gravity Drainage considering Thermal Convection

Zhang

et al. 2021

Geofluids

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Steam-assisted gravity drainage (SAGD) is an important method used in the development of heavy oil. A heat transfer model in the SAGD production process is established based on the heat transfer effect caused by the temperature difference at the front edge of the steam chamber and the heat convection effect caused by the pressure difference. The observation well temperature method is used in this model to calculate the horizontal expansion speed of the steam chamber. In this manner, an expansion speed model considering heat convection and heat conduction is established for a steam chamber with a steam-assisted gravity drainage system. By comparing this with the production data extracted from the Fengcheng Oilfield target block, it is verified that the model can be effectively applied for actual field development. Simultaneously, by using the derived model, the temperature distribution at the edge of the steam chamber and production forecast can be predicted. Sensitivity analysis of the expansion rate of the steam chamber demonstrates that the larger the thermal conductivity, the faster is the steam chamber horizontal expansion speed, and the two are positively correlated; the larger the reservoir heat capacity, the slower is the steam chamber horizontal expansion speed. A larger heat capacity of the convective liquid indicates that there are more water components in the convective liquid, the viscosity of the convective liquid is low, and the expansion speed of the steam chamber increases accordingly. This research closely integrates theory with actual field production and provides theoretical support for the development of heavy oil reservoirs.

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“…In geothermal simulations, the mass and energy formulations are often tightly coupled because of the fluid thermodynamic properties ( Coats et al, 1974;Chen et al, 2019 ). The fully-coupled fully-implicit approach is generally adopted to solve the system of equations in a robust way.…”

Section: Introductionmentioning

confidence: 99%

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

Hoop

Voskov

Bertotti

et al. 2021

Preprint

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Multiphase mass and heat transfer are ubiquitous in the subsurface within manifold applications. The presence of fractures over several scales and complex geometry magnifies the uncertainty of the heat transfer phenomena, which will significantly impact, or even dominate, the dynamic transport process. Capturing the details of fluid and heat transport within the fractured system is beneficial to the subsurface operations. However, accurate modeling methodologies for thermal high-enthalpy multiphase flow within fractured reservoirs are quite limited. In this work, multiphase flow in fractured geothermal reservoirs is numerically investigated. A discrete-fracture model is utilized to describe the fractured system. To characterize the thermal transport process accurately and efficiently, the resolution of discretization is necessarily optimized. A synthetic fracture model is firstly selected to run on different levels of discretization with different initial thermodynamic conditions. A comprehensive analysis is conducted to compare the convergence and computational efficiency of simulations. The numerical scheme is implemented within the Delft Advanced Research Terra Simulator (DARTS), which can provide fast and robust simulation to energy applications in the subsurface. Based on the converged numerical solutions, a thermal Péclet number is defined to characterize the interplay between thermal convection and conduction, which are the two governing mechanisms in geothermal development. Different heat transfer stages are recognized on the Péclet curve in conjunction with production regimes of the synthetic fractured reservoir. A fracture network, sketched and scaled up from a digital map of a realistic outcrop, is then utilized to perform a sensitivity analysis of the key parameters influencing the heat and mass transfer. Thermal propagation and Péclet number are found to be sensitive to flow rate and thermal parameters (e.g., rock heat conductivity and heat capacity). This paper presents a numerical simulation framework for fractured geothermal reservoirs, which provides the necessary procedures for practical investigations regarding geothermal developments with uncertainties.

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Comparison of multi-field coupling numerical simulation in hot dry rock thermal exploitation of enhanced geothermal systems

Cited by 17 publications

References 21 publications

Coupled Geomechanics and Flow Modeling of Fractured Reservoirs considering Matrix Permeability Anisotropy

Coupled Geomechanics and Flow Modeling of Fractured Reservoirs considering Matrix Permeability Anisotropy

Expansion Velocity Model of Steam-Assisted Gravity Drainage considering Thermal Convection

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

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