Salinization in a stratified aquifer induced by heat transfer from well casings

Lopik, Jan H. van; Hartog, Niels; Zaadnoordijk, Willem Jan; Cirkel, Dirk Gijsbert; Raoof, Amir

doi:10.1016/j.advwatres.2015.09.025

Cited by 19 publications

(28 citation statements)

References 47 publications

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“…To the best of the authors' knowledge, this is the first study that validates the approach of Langevin (2008) for axi-symmetric density-driven groundwater flow and thermal heat transport at high temperature contrasts (ΔT = 40-60°C). For accurate simulation of the thermal convection, a nonlinear density equation of state was implemented in the SEAWATv4 code (Van Lopik et al 2015). The modeling results accurately reproduce the experimental and numerical data sets of the field experiment at Auburn University (Molz et al 1983a;Buscheck et al 1983), while using both an axisymmetric SEAWATv4 model domain and the incorporated non-linear density equation of state (section 'Modeling of the pilot study at Auburn University').…”

Section: Model Validation On the Auburn University Field Experimentsmentioning

confidence: 99%

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The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

2016

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The efficiency of heat recovery in high-temperature (>60°C) aquifer thermal energy storage (HT-ATES) systems is limited due to the buoyancy of the injected hot water. This study investigates the potential to improve the efficiency through compensation of the density difference by increased salinity of the injected hot water for a single injection-recovery well scheme. The proposed method was tested through numerical modeling with SEAWATv4, considering seasonal HT-ATES with four consecutive injection-storage-recovery cycles. Recovery efficiencies for the consecutive cycles were investigated for six cases with three simulated scenarios: (a) regular HT-ATES, (b) HT-ATES with density difference compensation using saline water, and (c) theoretical regular HT-ATES without free thermal convection. For the reference case, in which 80°C water was injected into a high-permeability aquifer, regular HT-ATES had an efficiency of 0.40 after four consecutive recovery cycles. The density difference compensation method resulted in an efficiency of 0.69, approximating the theoretical case (0.76). Sensitivity analysis showed that the net efficiency increase by using the density difference compensation method instead of regular HT-ATES is greater for higher aquifer hydraulic conductivity, larger temperature difference between injection water and ambient groundwater, smaller injection volume, and larger aquifer thickness. This means that density difference compensation allows the application of HT-ATES in thicker, more permeable aquifers and with larger temperatures than would be considered for regular HT-ATES systems.

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Section: Model Validation On the Auburn University Field Experimentsmentioning

confidence: 99%

“…A non-linear density equation of state derived by Sharqawy et al (2010) was used in the SEAWAT code as described by Van Lopik et al (2015) to accurately simulate the temperature-density relation over large temperature ranges (see Eq. 2).…”

Section: Seawatmentioning

confidence: 99%

The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

2016

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“…For instance, in applications involving injection of hot fluids inside wells (i.e., geothermal, gas, and oil wells) and in steam injection, there are significant heat losses that create a temperature gradient in the aquifers. In salinized aquifers, this creates an interaction with the existing salinity gradient (van Lopik et al, 2015). Thus, in such a case, it is important to understand the effect of temperature gradient on mass flux entering the domain and the impact of salinity gradient on heat flux, which is the main objective of this section.…”

Section: Understanding the Effects Of Temperature And Concentration Gmentioning

confidence: 99%

A Fourier Series Solution for Transient Three‐Dimensional Thermohaline Convection in Porous Enclosures

Tabrizinejadas

Fahs

Ataie-Ashtiani³

et al. 2020

Water Resources Research

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Thermohaline convection (THC) in porous media is frequently investigated using the problem of porous enclosure. Most of the existing modeling-based studies are limited to 2-D simulations, because 2-D assumption is widely used to deal with computational requirement of 3-D numerical solutions. Analytical solutions serve as an alternative to deal with computational requirement of numerical solutions. Existing analytical solutions of THC are mostly limited to 2-D and also under steady-state regime. In this work, we develop a meshless 3-D semianalytical solution for the problem of THC in a porous box under crossed thermal and solute gradients, for both steady state and transient regimes. The semianalytical solution is developed using the Fourier series (FS) method applied to the vector potential form of the governing equations. The extension to transient solutions represents an important technical feature of this work, as the applications of the FS method to density-driven problems have been limited to steady-state conditions. The FS solution is validated against a finite element solution obtained using COMSOL Multiphysics. Numerical experiments show the worthiness of the developed FS solution as a benchmark because it clearly allows making distinction between different numerical techniques. The effects of governing parameters on three-dimensional THC have not been investigated previously. We perform a detailed parameter sensitivity analysis to address this gap. A vortex convective flow is observed and the orientation and intensity of the flow is sensitive to the gravity number. The increase in the temperature gradient reduces the salinity flux.

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“…where T is the temperature of the water [ • C] and S the total salt concentration [kg m −3 ] Lopik et al, 2015;Thorne et al, 2006). However, the slope of this linear approximation for the temperature influence is too steep over the range of 5 to 15 • C in which ATES operate.…”

Section: The Effect Of Salt Concentration and Temperature On Density mentioning

confidence: 99%

The effect of a density gradient in groundwater on ATES system efficiency and subsurface space use

Bloemendal

Olsthoorn

2018

Adv. Geosci.

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Abstract. A heat pump combined with Aquifer Thermal Energy Storage (ATES) has high potential in efficiently and sustainably providing thermal energy for space heating and cooling. This makes the subsurface, including its groundwater, of crucial importance for primary energy savings. ATES systems are often placed in aquifers in which salinity increases with depth. This is the case in coastal areas where also the demand for ATES application is high due to high degrees of urbanization in those areas. The seasonally alternating extraction and re-injection between ATES wells disturbs the preexisting ambient salinity gradient causing horizontal density gradients, which trigger buoyancy flow, which in turn affects the recovery efficiency of the stored thermal energy.This section uses analytical and numerical methods to understand and explain the impact of buoyancy flow on the efficiency of ATES in such situations, and to quantify the magnitude of this impact relative to other thermal energy losses. The results of this research show that losses due to buoyancy flow may become considerable at (a relatively large) ambient density gradients of over 0.5 kg m −3 m −1 in combination with a vertical hydraulic conductivity of more than 5 m day −1 . Monowell systems suffer more from buoyancy losses than do doublet systems under similar conditions.

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Salinization in a stratified aquifer induced by heat transfer from well casings

Cited by 19 publications

References 47 publications

The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

A Fourier Series Solution for Transient Three‐Dimensional Thermohaline Convection in Porous Enclosures

The effect of a density gradient in groundwater on ATES system efficiency and subsurface space use

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