Constraining the uncertainty in fracture geometry using tracer tests

Johnston, Peter Benjamin; Atkinson, T. C.; Barker, John A.; Odling, Noelle E.

doi:10.1007/s10040-008-0378-y

Cited by 10 publications

(5 citation statements)

References 18 publications

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“…This consistent behaviour suggests that an equivalent porous medium assumption may be reasonable, although it remains possible that this behaviour can arise from a 'sub continuum' (Johnston et al, 2009). …”

Section: Breakthrough Curve Shapementioning

confidence: 99%

Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

et al. 2015

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Two column tests were performed in conditions emulating vertical flow beneath the leachate table in a biologically active landfill to determine dominant transport mechanisms occurring in landfills. An improved understanding of contaminant transport process in wastes is required for developing better predictions about potential length of the long term aftercare of landfills, currently measured in timescales of centuries. Three tracers (lithium, bromide and deuterium) were used. Lithium did not behave conservatively. Given that lithium has been used extensively for tracing in landfill wastes, the tracer itself and the findings of previous tests which assume that it has behaved conservatively may need revisiting.The smaller column test could not be fitted with continuum models, probably because the volume of waste was below a representative elemental volume. Modelling compared advection-dispersion (AD), dual porosity (DP) and hybrid AD-DP models. Of these models, the DP model was found to be the most suitable. Although there is good evidence to suggest that diffusion is an important transport mechanism, the breakthrough curves of the different tracers did not differ from each other as would be predicted based

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Section: Breakthrough Curve Shapementioning

confidence: 99%

Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

et al. 2015

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“…In this method, a tracer pulse is injected into a well and its production from other well(s) is used to infer the fracture network [Johnston et al, 2005[Johnston et al, , 2009, the existence of flow barriers, and flood patterns. We hypothesize that core-scale breakthrough tracer profiles carry the potential to identify pore-scale void space topology.…”

Section: Introductionmentioning

confidence: 99%

A forward analysis on the applicability of tracer breakthrough profiles in revealing the pore structure of tight gas sandstone and carbonate rocks

Mehmani

Prodanović

et al. 2015

Water Resources Research

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We explore tracer breakthrough profiles (TBP) as a macroscopic property to infer the porespace topology of tight gas sandstone and carbonate rocks at the core scale. The following features were modeled via three-dimensional multiscale networks: microporosity within dissolved grains and pore-filling clay, cementation in the absence and presence of microporosity (each classified into uniform, porepreferred, and throat-preferred modes), layering, vug, and microcrack inclusion. A priori knowledge of the extent and location of each process was assumed to be known. With the exception of an equal importance of macropores and pore-filling micropores, TBPs show little sensitivity to the fraction of micropores present. In general, significant sensitivity of the TBPs was observed for uniform and throat-preferred cementation. Layering parallel to the fluid flow direction had a considerable impact on TBPs whereas layering perpendicular to flow did not. Microcrack orientations seemed of minor importance in affecting TBPs.

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“…PCA (sometimes called “proper orthogonal decomposition”) is a statistical tool common to engineering sciences. PCA is particularly useful in the analysis of data sets with a large number of independent variables (e.g., Cui et al, 2015; Johnston et al, 2009; Kitanidis & Lee, 2014; Lee & Kitanidis, 2014; Li & Jafarpour, 2010; van Doren et al, 2006; Vo & Durlofsky, 2014; etc.). In the current study, PCA reduces the number of unknown parameters requiring estimation via the inverse model by targeting larger, spatially correlated regions of the aperture field.…”

Section: Methodsmentioning

confidence: 99%

Predictive Inverse Model for Advective Heat Transfer in a Short‐Circuited Fracture: Dimensional Analysis, Machine Learning, and Field Demonstration

Hawkins

Fox

Koch

et al. 2020

Water Resources Research

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Identifying fluid flow maldistribution in planar geometries is a well-established problem in subsurface science/engineering. Of particular importance to the thermal performance of enhanced (or "engineered") geothermal systems is identifying the existence of nonuniform (i.e., heterogeneous) permeability and subsequently predicting advective heat transfer. Here, machine learning via a genetic algorithm (GA) identifies the spatial distribution of an unknown permeability field in a two-dimensional Hele-Shaw geometry (i.e., parallel plates). The inverse problem is solved by minimizing the L 2 norm between simulated residence time distribution (RTD) and measurements of an inert tracer breakthrough curve (BTC) (C-Dot nanoparticle). Principal component analysis (PCA) of spatially correlated permeability fields enabled reduction of the parameter space by more than a factor of 10 and restricted the inverse search to reservoir-scale permeability variations. Thermal experiments and tracer tests conducted at the mesoscale Altona Field Laboratory (AFL) demonstrate that the method accurately predicts the effects of extreme flow channeling on heat transfer in a single bedding-plane rock fracture. However, this is only true when the permeability distributions provide adequate matches to both tracer RTD and frictional pressure loss. Without good agreement to frictional pressure loss, it is still possible to match a simulated RTD to measurements, but subsequent predictions of heat transfer are grossly inaccurate. The results of this study suggest that it is possible to anticipate the thermal effects of flow maldistribution, but only if both simulated RTDs and frictional pressure loss between fluid inlets and outlets are in good agreement with measurements.

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Constraining the uncertainty in fracture geometry using tracer tests

Cited by 10 publications

References 18 publications

Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

A forward analysis on the applicability of tracer breakthrough profiles in revealing the pore structure of tight gas sandstone and carbonate rocks

Predictive Inverse Model for Advective Heat Transfer in a Short‐Circuited Fracture: Dimensional Analysis, Machine Learning, and Field Demonstration

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