The effects of thermal deformation on flow in a jointed geothermal reservoir

Swenson, Daniel; Hardeman, Brian

doi:10.1016/s1365-1609(97)00285-2

Cited by 10 publications

(2 citation statements)

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“…The test case is designed to mimic the semi-analytical similarity solution available in [40], which has been used to verify numerical codes such as ROCMAS II [7], Geocrack [41], and FEHM [42]. Test parameters are referred to those of [42].…”

Section: Example 3: Fluid Injection Into a Discrete Fracture-rock Matmentioning

confidence: 99%

Lower‐dimensional interface elements with local enrichment: application to coupled hydro‐mechanical problems in discretely fractured porous media

Watanabe

Wang

Taron

et al. 2012

Numerical Meth Engineering

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SUMMARY In this study, we develop lower‐dimensional interface elements to represent preexisting fractures in rock material, focusing on finite element analysis of coupled hydro‐mechanical problems in discrete fractures–porous media systems. The method adopts local enrichment approximations for a discontinuous displacement and a fracture relative displacement function. Multiple and intersected fractures can be treated with the new scheme. Moreover, the method requires less mesh dependencies for accurate finiteelement approximations compared with the conventional interface element method. In particular, for coupled problems, the method allows for the use of a single mesh for both mechanical and other related processes such as flow and transport. For verification purposes, several numerical examples are examined in detail. Application to a coupled hydro‐mechanical problem is demonstrated with fluid injection into a single fracture. The numerical examples prove that the proposed method produces results in strong agreement with reference solutions. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Example 3: Fluid Injection Into a Discrete Fracture-rock Matmentioning

confidence: 99%

Lower‐dimensional interface elements with local enrichment: application to coupled hydro‐mechanical problems in discretely fractured porous media

Watanabe

Wang

Taron

et al. 2012

Numerical Meth Engineering

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“…Most of the existing studies related to EGS [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] are based on high-fidelity numerical simulations. These simulations are performed to gain detailed understanding of the physical processes taking place in EGS reservoirs.…”

Section: Introduction and Problem Descriptionmentioning

confidence: 99%

Regression-based reduced-order models to predict transient thermal output for enhanced geothermal systems

et al. 2017

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Reduced-order modeling is a promising approach, as many phenomena can be described by a few parameters/mechanisms. An advantage and attractive aspect of a reduced-order model is that it is computational inexpensive to evaluate when compared to running a high-fidelity numerical simulation. A reduced-order model takes couple of seconds to run on a laptop while a high-fidelity simulation may take couple of hours to run on a high-performance computing cluster. The goal of this paper is to assess the utility of regression-based Reduced-Order Models (ROMs) developed from high-fidelity numerical simulations for predicting transient thermal power output for an enhanced geothermal reservoir while explicitly accounting for uncertainties in the subsurface system and site-specific details. Numerical simulations are performed based on equally spaced values in the specified range of model parameters. Key sensitive parameters are then identified from these simulations, which are fracture zone permeability, well/skin factor, bottom hole pressure, and injection flow rate. We found the fracture zone permeability to be the most sensitive parameter. The fracture zone permeability along with time, are used to build regression-based ROMs for the thermal power output. The ROMs are trained and validated using detailed physics-based numerical simulations. Finally, predictions from the ROMs are then compared with field data. We propose three different ROMs with different levels of model parsimony, each describing key and essential features of the power production curves. The coefficients in proposed regression-based ROMs are developed by minimizing a non-linear least-squares misfit function using Levenberg-Marquardt algorithm. The misfit function is based on the difference between numerical simulation data and reduced-order model. ROM-1 is constructed based on polynomials upto fourth order. ROM-1 is able to accurately reproduce the power output of numerical simulations for low values of permeabilities and certain features of the field-scale data. ROM-2 is a model with more analytical functions consisting of polynomials upto order eight, exponential functions and smooth approximations of Heaviside functions, and accurately describes the field-data. At higher permeabilities, ROM-2 reproduces numerical results better than ROM-1, however, there is a considerable deviation from numerical results at low fracture zone permeabilities. ROM-3 consists of polynomials upto order ten, and is developed by taking the best aspects of ROM-1 and ROM-2. ROM-1 is relatively parsimonious than ROM-2 and ROM-3, while ROM-2 overfits the data. ROM-3 on the other hand, provides a middle ground for model parsimony. Based on R 2 -values for training, validation, and prediction data sets we found that ROM-3 is better model than ROM-2 and ROM-1. For predicting thermal drawdown in EGS applications, where high fracture zone permeabilities (typically greater than 10 −15 m 2 ) are desired, ROM-2 and ROM-3 outperform ROM-1. As per computational time, all the ROMs ...

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McClure

Horne

2013

Discrete Fracture Network Modeling of Hydraulic Stimulation

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The effects of thermal deformation on flow in a jointed geothermal reservoir

Cited by 10 publications

References 0 publications

Lower‐dimensional interface elements with local enrichment: application to coupled hydro‐mechanical problems in discretely fractured porous media

Lower‐dimensional interface elements with local enrichment: application to coupled hydro‐mechanical problems in discretely fractured porous media

Regression-based reduced-order models to predict transient thermal output for enhanced geothermal systems

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