The hydraulic efficiency of single fractures: correcting the cubic law parameterization for self-affine surface roughness and fracture closure
- Publication type:
- Journal article
- Metadata:
-
- Autoren
- Maximilian O Kottwitz
- Anton A Popov
- Tobias S Baumann
- Boris JP Kaus
- Autoren-URL
- https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=fis-test-1&SrcAuth=WosAPI&KeyUT=WOS:000537807300001&DestLinkType=FullRecord&DestApp=WOS_CPL
- DOI
- 10.5194/se-11-947-2020
- eISSN
- 1869-9529
- Externe Identifier
- Clarivate Analytics Document Solution ID: LU5PN
- ISSN
- 1869-9510
- Ausgabe der Veröffentlichung
- 3
- Zeitschrift
- SOLID EARTH
- Paginierung
- 947 - 957
- Datum der Veröffentlichung
- 2020
- Status
- Published
- Titel
- The hydraulic efficiency of single fractures: correcting the cubic law parameterization for self-affine surface roughness and fracture closure
- Sub types
- Article
- Ausgabe der Zeitschrift
- 11
Data source: Web of Science (Lite)
- Other metadata sources:
-
- Abstract
- <jats:p>Abstract. Quantifying the hydraulic properties of single fractures is a fundamental requirement to understand fluid flow in fractured reservoirs. For an ideal planar fracture, the effective flow is proportional to the cube of the fracture aperture. In contrast, real fractures are rarely planar, and correcting the cubic law in terms of fracture roughness has therefore been a subject of numerous studies in the past. Several empirical relationships between hydraulic and mechanical aperture have been proposed based on statistical variations of the aperture field. However, often, they exhibit non-unique solutions, attributed to the geometrical variety of naturally occurring fractures. In this study, a non-dimensional fracture roughness quantification scheme is acquired, opposing effective surface area against relative fracture closure. This is used to capture deviations from the cubic law as a function of quantified fracture roughness, here termed hydraulic efficiencies. For that, we combine existing methods to generate synthetic 3-D fracture voxel models. Each fracture consists of two random, 25 cm2 wide self-affine surfaces with prescribed roughness amplitude, scaling exponent, and correlation length, which are separated by varying distances to form fracture configurations that are broadly spread in the newly formed two-parameter space (mean apertures in submillimeter range). First, we performed a percolation analysis on 600 000 synthetic fractures to narrow down the parameter space on which to conduct fluid flow simulations. This revealed that the fractional amount of contact and the percolation probability solely depend on the relative fracture closure. Next, Stokes flow calculations are performed, using a 3-D finite differences code on 6400 fracture models to compute directional permeabilities. The deviations from the cubic law prediction and their statistical variability for equal roughness configurations were quantified. The resulting 2-D solution fields reveal decreasing cubic law accordance down to 1 % for extreme roughness configurations. We show that the non-uniqueness of the results significantly reduces if the correlation length of the aperture field is much smaller than the spatial extent of the fracture. An equation was provided that predicts the average behavior of hydraulic efficiencies and respective fracture permeabilities as a function of their statistical properties. A model to capture fluctuations around that average behavior with respect to their correlation lengths has been proposed. Numerical inaccuracies were quantified with a resolution test, revealing an error of 7 %. By this, we propose a revised parameterization for the permeability of rough single fractures, which takes numerical inaccuracies of the flow calculations into account. We show that this approach is more accurate compared to existing formulations. It can be employed to estimate the permeability of fractures if a measure of fracture roughness is available, and it can readily be incorporated in discrete fracture network modeling approaches. </jats:p>
- Autoren
- Maximilian O Kottwitz
- Anton A Popov
- Tobias S Baumann
- Boris JP Kaus
- DOI
- 10.5194/se-11-947-2020
- eISSN
- 1869-9529
- Ausgabe der Veröffentlichung
- 3
- Zeitschrift
- Solid Earth
- Sprache
- en
- Online publication date
- 2020
- Paginierung
- 947 - 957
- Status
- Published online
- Herausgeber
- Copernicus GmbH
- Herausgeber URL
- http://dx.doi.org/10.5194/se-11-947-2020
- Datum der Datenerfassung
- 2020
- Titel
- The hydraulic efficiency of single fractures: correcting the cubic law parameterization for self-affine surface roughness and fracture closure
- Ausgabe der Zeitschrift
- 11
Data source: Crossref
- Author's licence
- CC-BY
- Autoren
- Maximilian O Kottwitz
- Anton A Popov
- Tobias S Baumann
- Boris JP Kaus
- Hosting institution
- Universitätsbibliothek Mainz
- Sammlungen
- JGU-Publikationen
- Resource version
- Published version
- DOI
- 10.5194/se-11-947-2020
- Funding acknowledgements
- DFG, Open Access-Publizieren Universität Mainz / Universitätsmedizin Mainz
- File(s) embargoed
- false
- Open access
- true
- ISSN
- 1869-9529
- Ausgabe der Veröffentlichung
- 3
- Zeitschrift
- Solid earth
- Schlüsselwörter
- 550 Geowissenschaften
- 550 Earth sciences
- Sprache
- eng
- Open access status
- Open Access
- Paginierung
- 947 - 957
- Datum der Veröffentlichung
- 2020
- Public URL
- https://openscience.ub.uni-mainz.de/handle/20.500.12030/5608
- Herausgeber
- Copernicus Publ.
- Herausgeber URL
- https://doi.org/10.5194/se-11-947-2020
- Datum der Datenerfassung
- 2021
- Datum, an dem der Datensatz öffentlich gemacht wurde
- 2021
- Zugang
- Public
- Titel
- The hydraulic efficiency of single fractures : correcting the cubic law parameterization for self-affine surface roughness and fracture closure
- Ausgabe der Zeitschrift
- 11
Files
kottwitz_maximilian_o.-the_hydraulic_-20210128113758317.pdf
Data source: OPENSCIENCE.UB
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