Fracture flow due to hydrothermally induced quartz growth

Kling, Tobias; Schwarz, Jens-Oliver; Wendler, Frank; Enzmann, Frieder; Blum, Philipp

doi:10.1016/j.advwatres.2017.06.011

Cited by 30 publications

(30 citation statements)

References 97 publications

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“…The results presented in section demonstrate that 3‐D surface alterations, which play an important role during precipitation in a fracture, are sensitive to both mineral distribution and Da . However, the computational demands of the level‐set approach and other immersed boundary models, and the dependence of the 3‐D grid resolution on fracture aperture (typically O(10 −4 m)), limit the spatial scale of simulations (Kling et al, ; Li et al, ; Yu & Ladd, ). An alternative approach to representing mineral heterogeneity is through the use of equivalent homogenous fracture‐scale properties (Deng et al, ; Menefee et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…Because mineral reactions occur fastest along fluid-rock boundaries with the largest reactive surface area (Weeks & Gilmer, 2007), fluid-rock reactions can lead to heterogeneous surface alterations that are not captured using a 1-D alteration approach. This is particularly important during mineral precipitation, where mineral deposition can lead to nonuniformly distributed, and arbitrarily oriented, cements that extend across the fracture aperture (Ankit et al, 2015;Kling et al, 2017;Tokan-Lawal et al, 2015). Recent numerical studies have employed different immersed boundary methods, such as the level-set method, to represent surface alterations in the direction normal to the fracture surface (e.g., Li et al, 2010;Molins et al, 2017;Soulaine et al, 2017;Yu & Ladd, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Mineral Precipitation in Fractures: Using the Level‐Set Method to Quantify the Role of Mineral Heterogeneity on Transport Properties

Jones

Detwiler

2019

Water Resources Research

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We used a depth‐averaged reactive transport model to simulate transport of a supersaturated fluid through fractures and considered two models of precipitation‐induced surface alterations: (1) a localized 1‐D alteration of the surface and (2) a 3‐D alteration of the surface using the level‐set method. Comparing simulation results to a simple analytical solution for precipitation in a homogeneous (aperture and mineralogy) fracture demonstrated both models predict the alteration process reasonably well. However, comparing simulation results from both models to results from a recent experimental study of precipitation in a mineralogically heterogeneous fracture (Jones & Detwiler, 2016, https://doi.org/10.1002/2016GL069598) demonstrated that the ability of the 3‐D model to predict mineral growth across the aperture and in the fracture plane leads to much better agreement with the experimental observations. To quantify the role of reaction kinetics on the precipitation process, we ran additional simulations using the 3‐D evolution model for reaction rate constants ranging over 3 orders of magnitude. When the kinetics were much faster than the advective flux through the fracture, precipitation was focused near the inlet, which led to a transition from preferential flow near the inlet to more uniform flow near the outlet. When reaction kinetics were slow relative to advection, reaction sites grew uniformly throughout the fracture leading to the eventual formation of a single preferential flow path from inlet to outlet. Regardless of reaction rate, localization of precipitation reactions led to significant increases (3 to 20 times) in the time scale required to seal the fracture relative to a mineralogically homogeneous fracture.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mineral Precipitation in Fractures: Using the Level‐Set Method to Quantify the Role of Mineral Heterogeneity on Transport Properties

Jones

Detwiler

2019

Water Resources Research

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“…Furthermore, the hydraulic aperture of a fractured rock can also be characterized indirectly by statistical measurements of mechanical aperture such as image analysis of fracture profiles performed by progressively grinding an epoxy resin-fixed sample in predefined intervals (e.g., Snow, 1970;Hakami and Larsson, 1996;Konzuk and Kueper, 2004), fracture topography determination using profilometry (e.g., Brown and Scholz, 1985a, b;Matsuki, 1999), X-ray computer tomography (e.g., Kling et al, 2016), structure from motion photogrammetry (e.g., Corradetti et al, 2017;Zambrano et al, 2019), magnetic resonance imaging (e.g., Renshaw et al, 2000), and optical methods applied to rock replicas (e.g., Isakov et al, 2001;Ogilvie et al, 2003;Ogilvie et al, 2006). With known fracture surface topographies and fracture aperture patterns, flow-through properties or hydraulic apertures can be evaluated by numerical fluid flow simulations (e.g., Nemoto et al, 2009;Zambrano et al, 2019) or empirical correlations (e.g., Renshaw, 1995;Kling et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Measuring hydraulic fracture apertures: a comparison of methods

et al. 2020

Self Cite

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Abstract. Hydraulic fracture apertures predominantly control fluid transport in fractured rock masses. Hence, the objective of the current study is to investigate and compare three different laboratory-scale methods to determine hydraulic apertures in fractured (Fontainebleau and Flechtinger) sandstone samples with negligible matrix permeability. Direct measurements were performed by using a flow-through apparatus and a transient-airflow permeameter. In addition, a microscope camera permitted measuring the mechanical fracture apertures from which the corresponding hydraulic apertures were indirectly derived by applying various empirical correlations. Single fractures in the sample cores were generated artificially either by axial splitting or by a saw cut resulting in hydraulic apertures that ranged between 8 and 66 µm. Hydraulic apertures, accurately determined by the flow-through apparatus, are used to compare results obtained by the other methods. The transient-airflow permeameter delivers accurate values, particularly when repeated measurements along the full fracture width are performed. In this case, the derived mean hydraulic fracture apertures are in excellent quantitative agreement. When hydraulic apertures are calculated indirectly from optically determined mechanical apertures using empirical equations, they show larger variations that are difficult to compare with the flow-through-derived results. Variations in hydraulic apertures as observed between methods are almost certainly related to differences in sampled fracture volume. Overall, using direct flow-through measurements as a reference, this study demonstrates the applicability of portable methods to determine hydraulic fracture apertures at both the laboratory and outcrop scales.

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“…However, natural fracture walls show deviations from planarity, i.e., roughness, resulting in varying apertures within the fracture plane. On top of that, fluid-rock interactions like dissolution (Durham et al, 2001), erosion (Pyrak-Nolte and Nolte, 2016) and mineral growth (Kling et al, 2017) as well as the surrounding stress field (Zimmerman and Main, 2004;Azizmohammadi and Matthäi, 2017) further modify the geometry of a fracture, causing deviations of the parallel plate assumption.…”

Section: Introductionmentioning

confidence: 99%

The hydraulic efficiency of single fractures: Correcting the cubic law parameterization for self-affine surface roughness and fracture closure

Kottwitz¹,

Popov²,

Baumann³

et al. 2020

Preprint

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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. Yet, 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 upon 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 3D fracture voxel models. Each fracture consists of two random 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. 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 depends on the relative fracture closure. Next, Stokes flow calculations are performed, using a 3D 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 2D solution fields reveal decreasing cubic-law accordance's 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. Under this assumption, an equation was provided that predicts hydraulic efficiencies and respective fracture permeabilities with a mean error of 26.7 %. Numerical inaccuracies were quantified with a resolution test, adding another error of 7 % on top of the previous one. 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.

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Fracture flow due to hydrothermally induced quartz growth

Cited by 30 publications

References 97 publications

Mineral Precipitation in Fractures: Using the Level‐Set Method to Quantify the Role of Mineral Heterogeneity on Transport Properties

Mineral Precipitation in Fractures: Using the Level‐Set Method to Quantify the Role of Mineral Heterogeneity on Transport Properties

Measuring hydraulic fracture apertures: a comparison of methods

The hydraulic efficiency of single fractures: Correcting the cubic law parameterization for self-affine surface roughness and fracture closure

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