Quantitative Measurements of Fracture Aperture and Directional Roughness from Rock Cores

Tatone, B. S. A.; Grasselli, Giovanni

doi:10.1007/s00603-011-0219-5

Cited by 51 publications

(22 citation statements)

References 51 publications

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“…After the 3-D scanning, the digitized data were exported in xyz file format to estimate the JRC. The surface roughness parameter, Z 2 , the root-mean-square of the slope of a 2-D profile is widely used to correlate with JRC value (Jang et al, 2014;Tatone & Grasselli, 2012;Tse & Cruden, 1979;Yang et al, 2001;Yu & Vayssade, 1991). For a 2-D profile, Z 2 is given by the following:…”

Section: 1029/2018jb016045mentioning

confidence: 99%

Injection‐Induced Shear Slip and Permeability Enhancement in Granite Fractures

2018

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Shear stimulation, so‐called hydroshearing, is believed to reactivate critical or near‐critical preexisting fractures by pressurized fluid injection, causing them to slip and dilate for economic production from geothermal and unconventional petroleum reservoirs. However, little or no experiments have been conducted to directly probe the coupled hydromechanical responses and permeability evolution during fracture shearing. In this paper, we present the results of novel injection‐induced shear tests on cylindrical granite samples each containing a single tensile or saw cut fracture. The shear test on rough fractures demonstrates that retainable permeability enhancement can be achieved through dilatant shear slip. The characteristic stick‐slip behavior of the fracture during shearing is also observed. Fracture aperture controlled by effective normal stress dominates the fluid flow in stick state, while in slip state, the major contributor to production increase is the irreversible normal dilation caused by fracture shear slip. The experimental data show that depending on the fracture roughness, the fracture slip process includes two quasi‐static slip intervals with a slip velocity of ~10−9 to ~10−6 m/s and a dynamic slip interval with a slip velocity of ~10−7 to ~10−5 m/s. The fracture slip correlates well with the associated stress relaxation: a faster fracture slip induces a quicker stress relaxation, and vice versa. The influence of surface roughness on the hydromechanical responses during fracture shearing and the shear‐induced asperity degradation are also studied. The various experimental observations on rough and smooth fractures clearly indicate that the key component to shear stimulation is fracture self‐propping by asperities.

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Section: 1029/2018jb016045mentioning

confidence: 99%

Injection‐Induced Shear Slip and Permeability Enhancement in Granite Fractures

2018

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“…The hydraulic behavior of a blocky rock mass is more dependent on the characteristics of the system of fractures within the rock mss than the characteristics of the intact rock, and fractures represent conduits of enhanced hydraulic conductivity relative to the intact rock (Tatone, 2012). Therefore, the analysis of fluid flow through a single rough fracture has become a hot focus in many research areas, such as oil recovery, geothermal energy extraction groundwater flow and the underground disposal of CO 2 and radioactive waste.…”

Section: Introductionmentioning

confidence: 99%

“…The limitation of this kind of method is that the fracture surfaces are destroyed after measurement and the fracture cannot be used for any other testing. Recently, as non-contact techniques, such as triangulation method (Lanaro 2000, Grasselli 2002, Tatone & Grasselli 2009), laser scanning (Fardin 2004, Xia & Wang 2008, are widely employed to measure surface topography, methods named as referenced noncontact surface topography measurements (Tatone, 2012) are developed to measure the aperture distribution of a fracture (Brown & Scholz 1985, Lanaro 2000, Wang 2009). These methods are proposed to measure the fracture aperture indirectly based on the surface topography of the two fracture walls.…”

Section: Introductionmentioning

confidence: 99%

Assessment of two methods for quantitative measurement of rock fracture aperture

Xiao¹,

Deng²,

Xia³

2013

Rock Characterisation, Modelling and Engineering Design Methods

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Accurate measurement of aperture distribution plays an important role in evaluating the hydraulic behavior of rock fractures. In this paper, the authors are devoted to the assessment of two methods, proposed by Brown and Wang respectively, for quantitative measurement of fracture aperture distribution. The principles of the two methods are outlined firstly. Three groups of artificial marble fracture specimens are prepared and the surface topography data are obtained by a 3D laser scanning system. Then based on the surface topography data, each method is adopted to calculate the aperture distribution. The mean apertures of fracture specimens are obtained by conducting statistic analysis on the aperture distributions. Constant hydraulic head flow tests on fracture specimens are also performed for inversion calculation of the hydraulic aperture. Comparisons between the mean aperture and hydraulic aperture of fracture specimens are provided to assess the applicability and accuracy of the two methods for quantitative aperture measurement.

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“…A wide spectrum of measurement techniques, targeting different observation lengths, has been developed over the last 50 years. This includes: (1) contact methods such as the Barton comb (Morelli, ) and the stylus profilometer (Poon and Bhushan, ); (2) atomic force microscopy (Thom et al., ); and (3) non‐invasive optical techniques such as confocal microscopy (Ficker and Martišek, ), white‐light interferometry (Renard et al., ), laser triangulation (Martínez et al., ), structured light projection (Tatone and Grasselli, ) and photogrammetry (Lee and Ahn, ). The lateral and vertical resolution and accuracy of the measurement techniques depend on the underlying physical principles; each technique therefore has its own restrictive application range.…”

Section: Introductionmentioning

confidence: 99%

Focus stacking photogrammetry for micro‐scale roughness reconstruction: a methodological study

Olkowicz

Dąbrowski

Pluymakers

2019

The Photogrammetric Record

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In close‐range applications, it is unclear whether optical photogrammetry is capable of accurately reconstructing submillimetre‐scale roughness. This paper presents a study of fine‐scale rock fracture roughness measurements with a careful assessment of the error. The workflow combines the techniques of structure from motion with focus stacking, using consumer‐grade equipment and free or affordable software. The approach is tested firstly with synthetic data to check the influence of the number and position of cameras, object texture and image processing using focus stacking. Secondly, the optimised workflow is used to measure a natural shale rock fracture surface. To estimate the accuracy, the results were compared with a high‐precision reference dataset provided by white‐light interferometry. The standard deviation of error in the method is 6·5 μm, and is related with morphological structures with wavelengths below 150 μm and amplitudes smaller than 10 μm.

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Quantitative Measurements of Fracture Aperture and Directional Roughness from Rock Cores

Cited by 51 publications

References 51 publications

Injection‐Induced Shear Slip and Permeability Enhancement in Granite Fractures

Injection‐Induced Shear Slip and Permeability Enhancement in Granite Fractures

Assessment of two methods for quantitative measurement of rock fracture aperture

Focus stacking photogrammetry for micro‐scale roughness reconstruction: a methodological study

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