Pore-Scale Process Coupling and Effective Surface Reaction Rates in Heterogeneous Subsurface Materials

Liu, Chongxuan; Liu, Yuanyuan; Kerisit, Sebastien N.; Zachara, John M.

doi:10.2138/rmg.2015.80.06

Cited by 36 publications

(33 citation statements)

References 202 publications

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“…), as well as those of many synthetics play a critical role in controlling the physical properties of and processes in rocks (Emmanuel et al 2015;Navarre-Sitchler et al 2015;Royne and Jamtveit 2015, this volume), and the interaction between them and the fl uid that are stored, fl ow through, precipitate in (Stack 2015, this volume) and react with (Liu et al 2015;Molins 2015;Putnis 2015, this volume) them. The better we understand and can quantify those porous structures, the better will be our ability to model, understand and predict the evolution of geological environments, either under natural conditions or those such as CO 2 or radiological waste sequestration, or addition or removal of other fl uids from geological reservoirs.…”

Section: Discussionmentioning

confidence: 99%

Characterization and Analysis of Porosity and Pore Structures

Anovitz

Cole

2015

Reviews in Mineralogy and Geochemistry

799

480

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Section: Discussionmentioning

confidence: 99%

Characterization and Analysis of Porosity and Pore Structures

Anovitz

Cole

2015

Reviews in Mineralogy and Geochemistry

799

480

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“…Modeled mineral reaction rates are often based on laboratorydetermined rates; unfortunately, large discrepancies remain between observed field and laboratory rates, a mismatch which decreases the predictive value of such models when applied to new systems , Pham et al, 2011, Liu et al, 2015. While studies have suggested factors that contribute to these rate discrepancies (ie.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of accessible mineral surface areas for improved prediction of mineral reaction rates in porous media

Beckingham

Steefel

Swift

et al. 2017

Geochimica et Cosmochimica Acta

121

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The rates of mineral dissolution reactions in porous media are difficult to predict, in part because of a lack of understanding of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area used in reactive transport models for porous media are typically ad hoc and often based on average grain size, increased to account for surface roughness or decreased by several orders of magnitude to account for reduced surface reactivity of field as opposed to laboratory samples. In this study, accessible mineral surface areas are determined for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan) using a multi-scale image analysis based on synchrotron Xray microCT, SEMQEMSCAN, XRD, SANS, and FIB-SEM. This analysis not only accounts for accessibility of mineral surfaces to macro-pores, but also accessibility through connected micro-pores in smectite, the most abundant clay mineral in this sample. While the imaging analysis reveals that most of the micro-and macro-pores are well connected, some pore regions are unconnected and thus inaccessible to fluid flow and diffusion. To evaluate whether mineral accessible surface area accurately reflects reactive surface area a flow-through core experiment is performed and modeled at the continuum scale. The core experiment is performed under conditions replicating the pilot site and the evolution of effluent solutes in the aqueous phase is tracked.Various reactive surface area models are evaluated for their ability to capture the observed effluent chemistry, beginning with parameter values determined as a best fit to a disaggregated sediment experiment (Beckingham et al., 2016) described previously.Simulations that assume that all mineral surfaces are accessible (as in the disaggregated sediment experiment) over-predict the observed mineral reaction rates, suggesting that a reduction of RSA by a factor of 10-20 is required to match the core flood experimental data. While the fit of the effluent chemistry (and inferred mineral dissolution rates) greatly improve when the pore-accessible mineral surface areas are used, it was also necessary to include highly reactive glass phases to match the experimental observations, in agreement with conclusions from the disaggregated sediment experiment. It is hypothesized here that the 10-20 reduction in reactive surface areas based on the limited pore accessibility of reactive phases in core flood experiment may be reasonable for poorly sorted and cemented sediments like those at the Nagaoka site, although this reflects pore rather than larger scale heterogeneity.

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“…The heterogeneous distribution of SOC and its bioavailability due to local physical protection and chemical recalcitrance (Six et al 2002), preferential and matrix transport of substrates due to pore connectivity and local moisture content (Hunt 2004;Liu et al 2015aLiu et al , 2014Steefel and Maher 2009), and nonuniform formation of microbial colonies and biofilms due to local substrate availability and predation inhibition (He et al 2014;Kakumanu et al 2013;Or et al 2007;Xu et al 2014) have been observed to affect the rate of heterotrophic respiration and its correlation with moisture content in soils (Franzluebbers 1999;Moyano et al 2012). Understanding the pore-scale physical and biochemical processes associated with these heterogeneous properties as well as their manifestations at large scales is crucial to reduce the uncertainty of predicting the relationship between HR rate and moisture content in soil systems.…”

Section: Introductionmentioning

confidence: 99%

Pore-scale investigation on the response of heterotrophic respiration to moisture conditions in heterogeneous soils

et al. 2016

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The relationship between microbial respiration rate and soil moisture content is an important property for understanding and predicting soil organic carbon degradation, CO 2 production and emission, and their subsequent effects on climate change. This paper reports a pore-scale modeling study to investigate the response of heterotrophic respiration to moisture conditions in soils and to evaluate various factors that affect this response. X-ray computed tomography was used to derive soil pore structures, which were then used for pore-scale model investigation. The porescale results were then averaged to calculate the effective respiration rates as a function of water content in soils. The calculated effective respiration rate first increases and then decreases with increasing soil water content, showing a maximum respiration rate at water saturation degree of 0.75, which is consistent with field and laboratory observations. The relationship between the respiration rate and moisture content is affected by various factors, including pore-scale organic carbon bioavailability, the rate of oxygen delivery, soil pore structure and physical heterogeneity, soil clay content, and microbial drought resistivity. Overall, this study provides mechanistic insights into the soil respiration response to the change in moisture conditions, and reveals a complex relationship between heterotrophic microbial respiration rate and moisture content in soils that is affected by various hydrological, geophysical, and biochemical factors.

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Pore-Scale Process Coupling and Effective Surface Reaction Rates in Heterogeneous Subsurface Materials

Cited by 36 publications

References 202 publications

Characterization and Analysis of Porosity and Pore Structures

Characterization and Analysis of Porosity and Pore Structures

Evaluation of accessible mineral surface areas for improved prediction of mineral reaction rates in porous media

Pore-scale investigation on the response of heterotrophic respiration to moisture conditions in heterogeneous soils

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