On the impact of spatially heterogenous permeability on free convection in the Perth Basin, Australia

Niederau, Jan; Ebigbo, Anozie; Marquart, Gabriele; Arnold, Juliane; Clauser, Christoph

doi:10.1016/j.geothermics.2016.11.011

Cited by 14 publications

(16 citation statements)

References 20 publications

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“…The geological model in this manuscript is a 2D section extracted from a 3D geological model of the central Perth Basin presented in Niederau et al (2017). Its location is indicated in Fig.…”

Section: Geological Modelmentioning

confidence: 99%

“…The Perth Basin, a sedimentary rift basin in Western Australia, was extensively studied for its geothermal potential with focus on one prominent reservoir unit, the Yarragadee Aquifer. While the hydrothermal conditions in this aquifer are largely unknown (Pujol et al 2015), multiple modeling studies suggest that hydrothermal convection occurs within the Yarragadee Aquifer (Sheldon et al 2012;Schilling et al 2013;Niederau et al 2017). In particular, Sheldon et al (2012) show that temperature and salinity measurements in the Perth Basin indicate convective flow.…”

Section: Introductionmentioning

confidence: 99%

“…Convective heat transfer in sedimentary reservoir systems can significantly increase their geothermal potential, as hot water is transported to shallower depths by zones of upflow (Barbier 2002). However, this increased potential is connected to a similarly increased uncertainty, as these zones can be difficult to locate due to uncertain reservoir structure and properties (Rana et al 1979;Schilling et al 2013;Lipsey et al 2016;Niederau et al 2017), or as they are influenced active exploitation (Grant et al 1982). On the other hand, convection can increase the risk of success for geothermal projects, e.g., when boreholes are drilled in a zone of downflow.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we estimate the influence of different correlation lengths on the associated convection pattern by systematically varying the lateral correlation length of porosity and permeability in a 2D cross section of the Perth Basin model by Niederau et al (2017). For each correlation length, we generate a Monte Carlo ensemble comprising 240 ensemble members.…”

Section: Introductionmentioning

confidence: 99%

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Analyzing the influence of correlation length in permeability on convective systems in heterogeneous aquifers using entropy production

2019

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Hydrothermal convection in porous geothermal reservoir systems can be seen as a double-edged sword. On the one hand, regions of upflow in convective systems can increase the geothermal energy potential of the reservoir; on the other hand, convection introduces uncertainty, because it can be difficult to locate these regions of upflow. Several predictive criteria, such as the Rayleigh number, exist to estimate whether convection might occur under certain conditions. As such, it is of interest which factors influence locations of upwelling regions and how these factors can be determined. We use the thermodynamic measure entropy production to describe the influence of spatially heterogeneous permeability on a hydrothermal convection pattern in a 2D model of a hot sedimentary aquifer system in the Perth Basin, Western Australia. To this end, we set up a Monte Carlo study with multiple ensembles. Each ensemble contains several hundred realizations of spatially heterogeneous permeability. The ensembles only differ in the horizontal spatial continuity (i.e., correlation length) of permeability. The entropy production of the simulated ensembles shows that the convection patterns in our models drastically change with the introduction and increase of a finite, lateral correlation length in permeability. An initial decrease of the average entropy production number with increasing lateral correlation length shows that fewer ensemble members show convection. When neglecting the purely conductive ensembles in our analysis, no significant change in the number of convection cells is seen for lateral correlation lengths larger than 2000 m. The result suggests that the strength of convective heat transfer is not sensitive to changes in lateral correlation length beyond a specific factor. It does, however, change strongly compared to simulations with a homogeneous permeability field. As such, while the uncertainty in spatial continuity of permeability may not strongly influence the convective heat transfer, our findings show that it is important to consider spatial heterogeneity and continuity of permeability when simulating convective heat transfer in an aquifer.

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Section: Geological Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Analyzing the influence of correlation length in permeability on convective systems in heterogeneous aquifers using entropy production

2019

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“…A comprehensive understanding of the coupled heat transport and fluid flow systems in the subsurface is of high relevance for a wide range of applications and scientific studies [e.g., Emanuel , ; Turcotte and Schubert , ; Diersch and Kolditz , ; Malkovsky and Magri , ; Niederau et al ., ]. However, the accurate prediction of the complex flow behavior in hydrothermal systems remains a significant challenge, specifically in the presence of hydrothermal convection [ Schilling et al ., ; Schmeling and Marquart , ; Lipsey et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Entropy production in a box: Analysis of instabilities in confined hydrothermal systems

Börsing

Wellmann

Niederau

et al. 2017

Water Resources Research

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We evaluate if the concept of thermal entropy production can be used as a measure to characterize hydrothermal convection in a confined porous medium as a valuable, thermodynamically motivated addition to the standard Rayleigh number analysis. Entropy production has been used widely in the field of mechanical and chemical engineering as a way to characterize the thermodynamic state and irreversibility of an investigated system. Pioneering studies have since adapted these concepts to natural systems, and we apply this measure here to investigate the specific case of hydrothermal convection in a “box‐shaped” confined porous medium, as a simplified analog for, e.g., hydrothermal convection in deep geothermal aquifers. We perform various detailed numerical experiments to assess the response of the convective system to changing boundary conditions or domain aspect ratios, and then determine the resulting entropy production for each experiment. In systems close to the critical Rayleigh number, we derive results that are in accordance to the analytically derived predictions. At higher Rayleigh numbers, however, we observe multiple possible convection modes, and the analysis of the integrated entropy production reveals distinct curves of entropy production that provide an insight into the hydrothermal behavior in the system, both for cases of homogeneous materials, as well as for heterogeneous spatial material distributions. We conclude that the average thermal entropy production characterizes the internal behavior of hydrothermal systems with a meaningful thermodynamic measure, and we expect that it can be useful for the investigation of convection systems in many similar hydrogeological and geophysical settings.

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Internal Natural Convection: Heating from Below

Nield

Bejan

2017

Convection in Porous Media

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On the impact of spatially heterogenous permeability on free convection in the Perth Basin, Australia

Cited by 14 publications

References 20 publications

Analyzing the influence of correlation length in permeability on convective systems in heterogeneous aquifers using entropy production

Analyzing the influence of correlation length in permeability on convective systems in heterogeneous aquifers using entropy production

Entropy production in a box: Analysis of instabilities in confined hydrothermal systems

Internal Natural Convection: Heating from Below

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