On spurious water flow during numerical simulation of steam injection into water-saturated soil

Gudbjerg, Jacob; Trötschler, O.; Färber, A.; Sonnenborg, Torben O.; Jensen, Karsten H.

doi:10.1016/j.jconhyd.2004.07.003

Cited by 9 publications

(10 citation statements)

References 19 publications

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“…The original code was slightly modified to account for the distinct entry pressure when using the formulation of Brooks and Corey (1966) for the capillary pressure-saturation relationship. To avoid spurious pressure fluctuations, the method proposed by Gudbjerg et al (2004b) was applied. This method prevents unphysical flow of cold water into the steam zone, which would lead to pressure drops and dramatic reduction in timestep size.…”

Section: Numerical Modelmentioning

confidence: 99%

Three‐Dimensional Numerical Modeling of Steam Override Observed at a Full‐Scale Remediation of an Unconfined Aquifer

Gudbjerg¹,

Heron²,

Sonnenborg³

et al. 2005

Groundwater Monitoring Rem

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Steam injected below the water table tends to move upward because of buoyancy. This limits the horizontal steam zone development, which determines the optimal spacing between injection wells. In this study, observations indicating steam override at a full‐scale remediation of an unconfined aquifer are analyzed by numerical modeling using the code T2VOC. A simplified three‐dimensional (3D) numerical model is set up, which qualitatively shows the same mechanisms as observed at the site. By means of the model, it is found that it will be possible to achieve a larger horizontal extent of the steam zone in a layered geology compared to the homogeneous case. In the homogeneous case, the steam injection rate increases dramatically when the injection pressure is increased, which is necessary to achieve a larger horizontal development. The development of the steam zone under unconfined conditions is found to be a complex function of the geologic layering, the water table at steady‐state extraction, and the injection/extraction system. Because of this complexity, it will be difficult to predict steam behavior without site‐specific 3D numerical modeling.

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Section: Numerical Modelmentioning

confidence: 99%

Three‐Dimensional Numerical Modeling of Steam Override Observed at a Full‐Scale Remediation of an Unconfined Aquifer

Gudbjerg¹,

Heron²,

Sonnenborg³

et al. 2005

Groundwater Monitoring Rem

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“…Most of the field-and laboratory-scale studies of soil remediation with steam injection have been focused on the saturated zone (Tse et al, 2001;Gudbjerg et al, 2004a), while little attention has been paid to remediation of the unsaturated zone (Dablow et al, 2000;Schmidt et al, 2002). In fact, removal of NAPL from the unsaturated zone would certainly prevent the continued release of toxic substances that can impact in-door air quality.…”

Section: Introductionmentioning

confidence: 99%

Combining steam injection with hydraulic fracturing for the in situ remediation of the unsaturated zone of a fractured soil polluted by jet fuel

Nilsson

Tzovolou

Kasela

et al. 2011

Journal of Environmental Management

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“…The main NAPL recovery mechanisms are (Davis 1998;Class et al 2002): (1) the physical displacement by condensed water and steam itself (Hadim et al 1993;Gudbjerg et al 2004a); (2) the decrease of the interfacial tension and NAPL viscosity at elevated temperatures (She and Sleep 1998); (3) the steam distillation (Acierno et al 2004); (4) the steam stripping (Braass et al 2003); (5) the vaporization (Kuhlman 2002); (6) boilinginduced heat conduction from the steam zone (Gudbjerg et al 2004b); and (7) the contaminant desorption from the solid phase (Tse et al 2001).…”

mentioning

confidence: 99%

“…However, the majority of field-and laboratory-scale studies of soil remediation by steam injection have been focused on the saturated zone of relatively high-permeability porous media (Tse et al 2001;Gudbjerg et al 2004a), and little attention has been paid on the remediation of the unsaturated zone (Schmidt et al 2002). Theoretical (Falta et al 1992) and onedimensional experimental (Hadim et al 1993) studies have revealed that hydrocarbons having boiling points up to 175°C (e.g., jet fuel) may be removed completely behind the steam condensation front.…”

mentioning

confidence: 99%

Remediation of the unsaturated zone of NAPL-polluted low permeability soils with steam injection: an experimental study

et al. 2010

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Purpose Although steam injection has been studied extensively as a potential technology for the remediation of soils polluted by hydrocarbons, there is still an ambiguity concerning the applicability of the method to unsaturated and low permeability soils. The goal of the present work is to identify the dominant mechanisms of pollutant removal and evaluate the effectiveness of steam injection for a mixture of semi-volatile and non-volatile hydrocarbons, and the unsaturated zone of low permeability soils. Such information is helpful for the interpretation of the results from relevant field-scale experiments. Materials and methods An unsaturated and low permeability soil is polluted with a synthetic light non-aqueous phase liquid (LNAPL) which is a mixture of non-volatile and semivolatile hydrocarbons: n-dodecane (n-C12), n-decane (n-C10), 1,2,4-trimethylbenzene, methylcyclohexane. The soil is packed in a tank (0.5 m×0.55 m×0.12 m) of poly-methylmethacrylate, and two lenses of coarse-grained sand act as high-permeability hydraulic fractures, with the steam being injected through the lower one and effluent (water/nonaqueous phase liquid (NAPL)/gas) being extracted from the upper one. After the completion of the test, a great number of soil samples are analyzed with gas chromatography-flame ionization detection to map the spatial distribution of the concentration of NAPL-compounds and evaluate the NAPLremoval efficiency. Results and discussion The condensation of water in the pores of unsaturated soil may block the upward convective steam flow and alters locally the pore structure of the soil by creating high-permeability pathways. Thanks to these pathways, the upward flow of steam at high rates sweeps the vapors of NAPL (steam stripping) formed at temperatures lower than 100°C (steam distillation). The NAPL removal efficiency is satisfactory but non-uniform throughout the soil and is maximized in areas dominated by preferential flow paths and for the most volatile compounds. Conclusions In the unsaturated zone of a low-permeability soil, the removal of LNAPL with steam injection is enhanced in areas dominated by high-permeability preferential flow paths. The vaporization of semi-volatile and non-volatile compounds at temperatures lower than 100°C (steam distillation) coupled with steam stripping are the dominant mechanisms of LNAPL remediation.

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On spurious water flow during numerical simulation of steam injection into water-saturated soil

Cited by 9 publications

References 19 publications

Three‐Dimensional Numerical Modeling of Steam Override Observed at a Full‐Scale Remediation of an Unconfined Aquifer

Three‐Dimensional Numerical Modeling of Steam Override Observed at a Full‐Scale Remediation of an Unconfined Aquifer

Combining steam injection with hydraulic fracturing for the in situ remediation of the unsaturated zone of a fractured soil polluted by jet fuel

Remediation of the unsaturated zone of NAPL-polluted low permeability soils with steam injection: an experimental study

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