Pipes to Earth's subsurface: the role of  atmospheric conditions in controlling air  transport through boreholes and shafts

Levintal, Elad; Lensky, Nadav G.; Mushkin, Amit; Weisbrod, Noam

doi:10.5194/esd-9-1141-2018

Cited by 8 publications

(10 citation statements)

References 58 publications

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“…Therefore, it follows that borehole diameter governs which heat transfer mechanism, diffusion, or convection controls the thermal profile within the boreholes. TIC dependence on borehole diameter has been previously suggested (Levintal, Lensky, et al, 2018). Nevertheless, this is the first validation and quantification of TIC under field conditions using identical boundary conditions for different borehole diameters.…”

Section: Resultsmentioning

confidence: 80%

“…BP may contribute only where borehole pipes are permeable or when there is no pipe. In such cases, oscillating atmospheric pressure drives air exchange between the borehole and the surrounding vadose zone (Levintal, Lensky, et al, 2018; Neeper, 2003). Wind can also enhance evaporation, where high wind speed can potentially initiate high frequency pressure oscillations (Laemmel et al, 2017).…”

Section: Resultsmentioning

confidence: 99%

“…The contribution to gas exchange from near‐surface cavities is herein explored. Air transport through conduits (boreholes, shafts, and wells) is known to provide natural aeration of quarries or tunnels (Perrier & Le Mouël, 2016), change relative humidity (RH; see supporting information for acronym table) and impact carbon fluxes in karst systems (Auvray et al, 2008), enhance evaporation from lower water tables, impact the stability of carbon capture and storage processes (Haugan & Joos, 2004; Levintal, Lensky, et al, 2018), increase emissions of volatile organic compounds (VOCs) from contaminated soils (Boothroyd et al, 2016; Ronen et al, 2010), and drive emissions of greenhouse gases (GHGs) from open oil and water boreholes (Kang et al, 2014; Levintal et al, 2020; Levintal, Dragila, et al, 2018). Although diffusion drives gas transport through all cavities to some degree, for apertures greater than the scale of several cm, gas fluxes are strongly impacted by contributions from three advective mechanisms: barometric pumping (BP), thermal‐induced convection (TIC), and wind‐induced convection.…”

Section: Introductionmentioning

confidence: 99%

“…Advection is responsible for greater gas exchange than diffusion. However, the relative contribution of these mechanisms depends on the geometry of the conduit, specifically the conduit aperture and depth (Levintal, Lensky, et al, 2018; Perina, 2014). This paper explores the effect of borehole size on gas exchange for the transition size between very small (diffusion‐dominated) and intermediate (advection‐dominated) diameters in the range of 0.1–0.4 m.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to atmospheric conditions, the borehole diameter and depth, and the surrounding rock/soil permeability play important roles in the initiation and magnitude of the three advective air transport mechanisms. Recent studies, which used simulations and field results, indicated that an increase in borehole diameter will decrease the vertical air velocity within the borehole generated by BP while increasing the air velocity generated by TIC (Levintal, Lensky, et al, 2018; You et al, 2010). Thus, greater diameters favor TIC over BP.…”

Section: Introductionmentioning

confidence: 99%

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Borehole Diameter Controls Thermal‐Induced Convection and Evaporation From a Shallow Water Table

Levintal

Dragila

Lensky

et al. 2020

Geophysical Research Letters

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Understanding air exchange via boreholes, shafts, and wells is important for Earth and environmental sciences because of their potential role for increased evaporation and greenhouse gas emissions. Here, we investigated the effect of atmospheric temperature variability on air transport via a borehole as a function of its diameter. Field experiment included five boreholes with diameters ranging from 0.10 to 0.38 m and a depth of 3 m with an artificial water table at −2.7 m. Temperature was recorded in each borehole at 1-min intervals for 1 year. Diurnal and seasonal air temperature changes triggered thermal instability, mainly during winter nights, which initiated thermal-induced convection within the boreholes. The thermal-induced convection penetrated deeper into the borehole as the diameter increased, doubling the water table evaporation rate for the largest borehole relative to the smallest. Borehole diameter plays an important role in controlling air exchange rates between the subsurface and the atmosphere. Plain Language Summary The Earth's surface is dotted with different types of boreholes and shafts with varying diameters and depths, which act like "straws" penetrating the Earth's subsurface whereby different types of gases can be emitted into the atmosphere from subsurface layers that were previously unexposed. To be able to calculate the quantities and rates of gas exchange, it is therefore important to understand the gas transport mechanisms within these "straws." In this study, we examined water vapor loss from a shallow water table using field measurements from five different human-made boreholes (3 m in depth). High-resolution temperature profiles and evaporation rates from the water table located 30 cm above the bottom of each borehole were used to explore gas transport. We show the importance of thermal-induced convection as a major air transport mechanism and its dependence on both borehole diameter and atmospheric conditions. The mechanism of thermally induced convection is similar to what controls cloud formation, in which warm (light) air moves upward to replace the cold (heavy) air above it. We found that the air transfer rate increases as borehole diameter increases and that boreholes emit more gas into the atmosphere, and at a higher rate, during winter than during summer.

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Borehole Diameter Controls Thermal‐Induced Convection and Evaporation From a Shallow Water Table

Levintal

Dragila

Lensky

et al. 2020

Geophysical Research Letters

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Forced and natural gas movement in dry sand – Barrel experiments and models

Ben‐Noah

Nitsan

Friedman

2020

Soil Science Soc of Amer J

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The physical processes governing advective and diffusive gas movement and distribution in dry soils are, in general, well understood and quantified. In this study, we derived and applied analytical and numerical models to describe these processes under different conditions and scenarios and conducted gas flow experiments in 200‐L barrels packed with dry quartz sand in a temperature‐controlled laboratory. We used either pure N2 (0% O2) or atmospheric air (20.9% O2) injection or gas extraction from (or into) buried point sources (or sinks) to examine the effects of (a) source depth, (b) source discharge rate, and (c) injection cycle period on gas concentration and pressure distribution. We further quantified the contribution of diffusion from the atmospheric soil surface for the different scenarios, made possible by injecting N2 and tracking the complementary O2 concentration [i.e. the difference between atmospheric (20.9%) and the measured soil O2 concentration]. An analytical solution for steady air flow from a point source in a finite, cylindrical domain is presented. The main findings are that air injection, and air extraction, are efficient at aerating the soil volume above the buried gas source or sink. On the other hand, air injection increases the aeration's effectiveness, especially below the source. Shortening the cycle period of gas injection increases gas‐use efficiency (i.e., increases the injected gas concentration) in most of the soil domain. The measurements were in good agreement with the results computed by the models’ analytical and numerical solutions.

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The “breathing spots” in karst areas—the sites of advective exchange of gases between soils and adjacent underground cavities

Faimon

Lang

Geršl

et al. 2020

Theor Appl Climatol

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Pipes to Earth's subsurface: the role of atmospheric conditions in controlling air transport through boreholes and shafts

Cited by 8 publications

References 58 publications

Borehole Diameter Controls Thermal‐Induced Convection and Evaporation From a Shallow Water Table

Borehole Diameter Controls Thermal‐Induced Convection and Evaporation From a Shallow Water Table

Forced and natural gas movement in dry sand – Barrel experiments and models

The “breathing spots” in karst areas—the sites of advective exchange of gases between soils and adjacent underground cavities

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