Method Comparison to Determine Hydraulic Apertures of Natural Fractures

Hale, Sina; Naab, Christoph; Butscher, Christoph; Blum, Philipp

doi:10.1007/s00603-019-01966-7

Cited by 16 publications

(16 citation statements)

References 34 publications

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“…The instrument is a portable handheld air permeameter designed to measure permeability in the range of 1 millidarcy (mD) to 10 darcys (D) on outcrop and core samples (Brown and Smith 2013). The ability of the instrument to measure the permeability of porous rock and fractures was shown in several studies (e.g., De Boever et al 2016;Filomena et al 2014;Hale et al 2019). It was also successfully used to evaluate aquifer heterogeneity and spatial variation of hydraulic aquifer properties (e.g., Huysmans et al 2008;Rogiers et al 2014a) and to relate permeability variation to diagenetic processes (e.g., Fischer et al 2013;Gaupp 1996;Molenaar et al 2015).…”

Section: Permeability Measurementsmentioning

confidence: 99%

Small-scale diagenetic facies heterogeneity controls porosity and permeability pattern in reservoir sandstones

Heidsiek

Butscher

Blum³

et al. 2020

Environ Earth Sci

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The fluvial-aeolian Upper Rotliegend sandstones from the Bebertal outcrop (Flechtingen High, Germany) are the famous reservoir analog for the deeply buried Upper Rotliegend gas reservoirs of the Southern Permian Basin. While most diagenetic and reservoir quality investigations are conducted on a meter scale, there is an emerging consensus that significant reservoir heterogeneity is inherited from diagenetic complexity at smaller scales. In this study, we utilize information about diagenetic products and processes at the pore- and plug-scale and analyze their impact on the heterogeneity of porosity, permeability, and cement patterns. Eodiagenetic poikilitic calcite cements, illite/iron oxide grain coatings, and the amount of infiltrated clay are responsible for mm- to cm-scale reservoir heterogeneities in the Parchim formation of the Upper Rotliegend sandstones. Using the Petrel E&P software platform, spatial fluctuations and spatial variations of permeability, porosity, and calcite cements are modeled and compared, offering opportunities for predicting small-scale reservoir rock properties based on diagenetic constraints.

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Section: Permeability Measurementsmentioning

confidence: 99%

Small-scale diagenetic facies heterogeneity controls porosity and permeability pattern in reservoir sandstones

Heidsiek

Butscher

Blum³

et al. 2020

Environ Earth Sci

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“…A is the cross-sectional area of the sample. In the case of the sample permeability being very large compared to the matrix permeability, it is reasonable to assume that the total amount of flow through the sample is equal to the flow through the artificial fracture (Hofmann et al, 2016). Then, based on the cubic law and the assumption of laminar flow through the fracture, the fracture permeability can be evaluated from the hydraulic aperture determined by using a parallel-plate approximation (Snow, 1969;Witherspoon et al, 1980;Milsch et al, 2016): where W is the fracture width equal to the sample diameter, k f is the fracture permeability, and a FTA is the hydraulic aperture obtained by the flow-through apparatus.…”

Section: Flow-through Apparatusmentioning

confidence: 99%

Measuring hydraulic fracture apertures: a comparison of methods

et al. 2020

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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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“…The axis of the niche is oriented almost normal to Gallery 04 and to the minimum principal stress direction of the in situ stress field (Yong et al, 2010). The niche is located in the upper shaly facies of the Opalinus Clay, which consists of dark gray, mostly mica and pyrite containing calcareous silty-sandy claystones (Hostettler et al, 2017). Bedding dips 45 • towards 150 • , and thus the niche axis is oriented perpendicular to the strike of the bedding.…”

Section: Study Sitementioning

confidence: 98%

“…The working principle of the device was outlined by Brown and Smith (2013) and illustrated in Fig. 1 of Hale et al (2020b). Further specifications are provided by New England Research, Inc. (2015).…”

Section: Air Permeametermentioning

confidence: 99%

Mechanical and hydraulic properties of the excavation damaged zone (EDZ) in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland

Hale

Ries

Jaeggi³

et al. 2021

Solid Earth

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Abstract. Construction of cavities in the subsurface is always accompanied by excavation damage. Especially in the context of deep geological nuclear waste disposal, the evolving excavation damaged zone (EDZ) in the near field of emplacement tunnels is of utmost importance concerning safety aspects. As the EDZ differs from the intact host rock due to enhanced hydraulic transmissivity and altered geomechanical behavior, reasonable and location-dependent input data on hydraulic and mechanical properties are crucial. Thus, in this study, a hydromechanical characterization of an EDZ in the Mont Terri underground rock laboratory, Switzerland, was performed using three different handheld devices: (1) air permeameter, (2) microscopic camera and (3) needle penetrometer. The discrete fracture network (DFN), consisting of artificially induced unloading joints and reactivated natural discontinuities, was investigated by a portable air permeameter and combined microscopic imaging with automatic evaluation. Geomechanical and geophysical characterization of the claystone was conducted based on needle penetrometer testing at the exposed rock surface. Within the EDZ, permeable fractures with a mean hydraulic aperture of 84 ± 23 µm are present. Under open conditions, self-sealing of fractures is suppressed, and cyclic long-term fracture aperture oscillations in combination with closure resulting from convergence processes is observed. Based on measured needle penetration indices, a uniaxial compressive strength of 30 ± 13 MPa (normal to bedding) and 18 ± 8 MPa (parallel to bedding) was determined. Enhanced strength and stiffness are directly related to near-surface desaturation of the claystone and a sharp decrease in water content from 6.6 wt % to 3.7 wt %. The presented methodological approach is particularly suitable for time-dependent monitoring of EDZs since measurements are nondestructive and do not change the actual state of the rock mass. This allows for a spatially resolved investigation of hydraulic and mechanical fracture apertures, fracture surface roughness, and physico-mechanical rock parameters and their intra-facies variability.

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Method Comparison to Determine Hydraulic Apertures of Natural Fractures

Cited by 16 publications

References 34 publications

Small-scale diagenetic facies heterogeneity controls porosity and permeability pattern in reservoir sandstones

Small-scale diagenetic facies heterogeneity controls porosity and permeability pattern in reservoir sandstones

Measuring hydraulic fracture apertures: a comparison of methods

Mechanical and hydraulic properties of the excavation damaged zone (EDZ) in the Opalinus Clay of the Mont Terri rock laboratory, Switzerland

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