Entrapment and Mobilization of Residual Oil in Bead Packs

Morrow, Norman R.; Chatzis, Ioannis; Taber, J.J.

doi:10.2118/14423-pa

Cited by 177 publications

(134 citation statements)

References 15 publications

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“…After entrapment of the gas phase from all three methods of emplacement the viscous forces, due to typical groundwater velocity, will be small relative to the capillary forces, and thus it will be difficult to mobilize the gas phase once it is emplaced. The viscous forces necessary for mobilization of a nonwetting phase that has been trapped are significantly greater than the viscous forces needed to prevent entrapment of the nonwetting phase initially [Morrow and Songkran, 1981; Morrow et al, 1985].…”

Section: Discussionmentioning

confidence: 99%

“…The dimensionless numbers of interest are the capillary number (viscous/capillary forces) and the bond number (buoyancy/capillary forces). At large capillary numbers, when the nonwetting phase is gas versus oil, the volume of trapped gas is slightly smaller than the volume of trapped oil [Morrow et al, 1985]. Plots of the bond number versus residual saturation shows that a water-air fluid pair gives a slightly smaller (1.5%) residual saturation compared to a water-oil fluid pair [Morrow and Songkran, 1981;Morrow et al, 1985].…”

Section: Volume Of Trapped Gasmentioning

confidence: 96%

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Experimental investigations for trapping oxygen gas in saturated porous media for in situ bioremediation

Fry¹,

Selker²,

Gorelick³

1997

Water Resources Research

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Abstract. Oxygen is often the rate-limiting factor in aerobic in situ bioremediation. This paper investigates the degree to which air or oxygen gas can be emplaced into the pore space of saturated porous media and provide a significant mass of oxygen. Column experiments were performed to test three emplacement methods: direct gas injection, injection of water supersaturated with gas, and injection of a hydrogen peroxide solution. The direct gas injection method fills 14-17% of the pore space with trapped gas. Water supersaturated with gas fills 18-27% of the pore space with a trapped gas phase, and hydrogen peroxide solution injections emplaces trapped gas in 17-55% of the pore space. In addition to supplying oxygen, gas entrapment causes a decrease in hydraulic conductivity which could be an advantage by decreasing the flow of contaminants offsite. The relative hydraulic conductivity of porous media with a trapped gas volume of 14-55% was 0.62-0.05. IntroductionAlternative methods are needed for introducing oxygen into groundwater for aerobic in situ bioremediation of contaminants. In situ bioremediation is often limited by the amount of oxygen available to the microorganisms in the subsurface. To degrade a simple hydrocarbon (e.g., benzene), approximately 3.1 times more oxygen than contaminant in mass/volume is necessary to meet the stoichiometric requirements. Since the solubility of oxygen in water is low, it is difficult to significantly increase the oxygen mass in a contaminated aquifer by dissolving the oxygen in water first before transferring it to the aquifer. Twenty-eight times more oxygen per volume can be stored in the gas phase than can be dissolved in water, assuming equilibrium based on Henry's law at 15øC.We are investigating whether a wall or zone of trapped gas bubbles can be emplaced into an otherwise-saturated porous medium and provide a substantial source of oxygen for bioremediation of contaminated groundwater (Figure 1). If 15% of the pore space can be filled with oxygen gas, 20 times more oxygen will be emplaced compared to the case in which oxygen is dissolved in the pore water in equilibrium with air. Once a wall or zone of oxygen bubbles is emplaced into an aquifer, the oxygen will be dissolved by the water and be potentially available for use by microorganisms in biodegradation. When the oxygen is used up, it can be emplaced again. This cycle may be repeated until the contaminant is degraded to levels that meet the regulatory requirement. Because trapped gas emplacement does not require continuous injection, a bubble wall or zone may be constructed using modified sampling equipment (e.g., a Hydropunch TM or GeoprobeTM), which will allow for much closer spacing of injection points than injection through a well casing. Here we refer to oxygen because it is the gas that is most widely needed for bioremediation of contaminated groundwater, but other gases, such as hydrogen and methane, which have been shown to be effective in remediation of contaminated groundwater, could also be introdu...

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Section: Discussionmentioning

confidence: 99%

Section: Volume Of Trapped Gasmentioning

confidence: 96%

Experimental investigations for trapping oxygen gas in saturated porous media for in situ bioremediation

Fry¹,

Selker²,

Gorelick³

1997

Water Resources Research

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“…They found that, on a local scale (~1 mm), the residual gas saturation increases with an increase in porosity. However, on a core scale, the residual gas saturation exhibits an inverse relationship with porosity [125,126]. These seemingly contradictory observations are actually the two different manifestations of the same immiscible displacement process.…”

Section: Model Analysis: First Order Approximationmentioning

confidence: 98%

Fundamental study of CO2-H2O-mineral interactions for carbon sequestration, with emphasis on the nature of the supercritical fluid-mineral interface.

Bryan¹,

Dewers²,

Heath³

et al. 2013

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In the supercritical CO 2 -water-mineral systems relevant to subsurface CO 2 sequestration, interfacial processes at the supercritical fluid-mineral interface will strongly affect core-and reservoir-scale hydrologic properties. Experimental and theoretical studies have shown that water films will form on mineral surfaces in supercritical CO 2 , but will be thinner than those that form in vadose zone environments at any given matric potential. The theoretical model presented here allows assessment of water saturation as a function of matric potential, a critical step for evaluating relative permeabilities the CO 2 sequestration environment. The experimental water adsorption studies, using Quartz Crystal Microbalance and Fourier Transform Infrared Spectroscopy methods, confirm the major conclusions of the adsorption/condensation model. Additional data provided by the FTIR study is that CO 2 intercalation into clays, if it occurs, does not involve carbonate or bicarbonate formation, or significant restriction of CO 2 mobility.We have shown that the water film that forms in supercritical CO 2 is reactive with common rock-forming minerals, including albite, orthoclase, labradorite, and muscovite. The experimental data indicate that reactivity is a function of water film thickness; at an activity of water of 0.9, the greatest extent of reaction in scCO 2 occurred in areas (step edges, surface pits) where capillary condensation thickened the water films. This suggests that dissolution/precipitation reactions may occur preferentially in small pores and pore throats, where it may have a disproportionately large effect on rock hydrologic properties.Finally, a theoretical model is presented here that describes the formation and movement of CO 2 ganglia in porous media, allowing assessment of the effect of pore size and structural heterogeneity on capillary trapping efficiency. The model results also suggest possible engineering approaches for optimizing trapping capacity and for monitoring ganglion formation in the subsurface. 6 ACKNOWLEDGMENTS

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“…N c is a dimensionless ratio quantifying the relative importance of viscous to capillary forces, i.e., N c = vμ/σ where v is the apparent velocity, μ is the viscosity of the invading phase, and σ is the interfacial tension (13). For homogeneous sandstones, remobilization typically occurs at N c of the order of 10 −5 , an effect known as capillary desaturation (14).…”

mentioning

confidence: 99%

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

Pak

Butler

Geiger

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

150

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Using X-ray computed microtomography, we have visualized and quantified the in situ structure of a trapped nonwetting phase (oil) in a highly heterogeneous carbonate rock after injecting a wetting phase (brine) at low and high capillary numbers. We imaged the process of capillary desaturation in 3D and demonstrated its impacts on the trapped nonwetting phase cluster size distribution. We have identified a previously unidentified pore-scale event during capillary desaturation. This pore-scale event, described as droplet fragmentation of the nonwetting phase, occurs in larger pores. It increases volumetric production of the nonwetting phase after capillary trapping and enlarges the fluid−fluid interface, which can enhance mass transfer between the phases. Droplet fragmentation therefore has implications for a range of multiphase flow processes in natural and engineered porous media with complex heterogeneous pore spaces.droplet fragmentation | X-ray computed microtomography | pore-scale imaging | heterogeneous porous media | carbonate rock M ultiphase fluid displacement processes in porous media are important for a broad range of natural and engineering applications such as transport of nonaqueous phase liquid contaminants in aquifers, oil and gas production from hydrocarbon reservoirs, subsurface CO 2 storage, or gas transport in fuel cells. Herein, capillary trapping is a fundamental mechanism that causes immobilization of a portion of the resident nonwetting phase when it is displaced by an invading wetting phase. As a result, production of the nonwetting phase is always less than 100%.The pore-scale physics of capillary trapping are broadly understood, as the underlying mechanisms such as piston-like displacement, snap-off and film development have been observed in physical micromodel experiments and quantitative theories have been established for them (1-4). The conventional view considers such pore-scale processes to occur between multiple pores, i.e., they are interpore processes and the pores are defined as volumes connected by narrower pore throats. By contrast, intrapore processes, as presented in this paper, are not well established in the literature. During drainage (i.e., where a nonwetting phase displaces the wetting phase), the wetting phase can establish films in the corners of the pores, which results in its continuous production and hence low residual saturations of the wetting phase. During imbibition (i.e., where the wetting phase displaces a nonwetting phase), swelling of the corner wetting films causes snap-off of the nonwetting phase, which results in capillary trapping of the nonwetting phase. The trapped nonwetting phase exists as disconnected ganglia within the pore network. Numerical pore network models have been developed to include these porelevel mechanisms with the aim of predicting the macroscopic flow properties of porous materials such as the structure of the phase distributions, residual saturation, relative permeability functions, and capillary pressure curves. Some of these mod...

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Entrapment and Mobilization of Residual Oil in Bead Packs

Cited by 177 publications

References 15 publications

Experimental investigations for trapping oxygen gas in saturated porous media for in situ bioremediation

Experimental investigations for trapping oxygen gas in saturated porous media for in situ bioremediation

Fundamental study of CO2-H2O-mineral interactions for carbon sequestration, with emphasis on the nature of the supercritical fluid-mineral interface.

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media

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