A Systematic Investigation Into the Control of Roughness on the Flow Properties of 3D‐Printed Fractures

Phillips, Tomos; Bultreys, Tom; Bisdom, Kevin; Kampman, Niko; Offenwert, Stefanie Van; Mascini, Arjen; Cnudde, Veerle; Busch, Andreas

doi:10.1029/2020wr028671

Cited by 30 publications

(10 citation statements)

References 187 publications

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“…In general, the numerically obtained permeability (dark blue balls) deviates from the cubic law (dark line), this is manifested by the fact that the calculated fracture permeability is all below the one predicted by the cubic law at the same mechanical apertures. This is consistent with many previous studies [8,15,29,49,52].…”

Section: Fracture Permeability Under Normal Stress From Numerical Sim...supporting

confidence: 94%

“…(a) Although both the connectivity metrics have been improved, and the connectivity metric Γ ′ grows to a greater extent than the connectivity metric Θ ′ (with an average growth of 12% vs. 8%), Θ ′ still has a higher permeability prediction accuracy than that of the Γ ′ (averagely about 18%). Notably, the fracture permeability prediction accuracy by the connectivity metric Θ ′ reaches more than 80%, which is comparable with most common permeability models obtained with laboratory experiments and numerical modeling ( [7,8,29,[53][54][55][56][57], see Figure 4). Moreover, the information required in this study is no more than that of common numerical modeling, yet presents fast and inexpensive computation [27].…”

Section: Fracture Permeability and Connectivity Metricssupporting

confidence: 78%

“…Synthetic fractures were used in this study to generate a large number of fractures with controllable surface properties. These were implemented by using SynFrac, which creates two opposing rough fracture surfaces that can well approximate natural rock surfaces by taking into account their statistical parameters, roughness, matchedness, and anisotropy [28][29][30]. The fracture size is 100 × 100 mm and discretized by 512 × 512 uniform square grid cells in the xy-plane.…”

Section: Fracture Aperture Generationmentioning

confidence: 99%

“…Fracture permeability obtained from the numerical simulations (blue balls) as a function of mechanical aperture. The data was compared with experimental data ([29]) and several previous derived models ([7,8,[53][54][55][56][57]).…”

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confidence: 99%

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A Connectivity Metrics-Based Approach for the Prediction of Stress-Dependent Fracture Permeability

Deng,

Shang,

2024

Water

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Rapid and accurate assessment of fracture permeability is critical for subsurface resource and energy development as well as rock engineering stability. Fracture permeability deviates from the classical cubic law under the effect of roughness, geological stress, as well as mining-induced stress. Conventional laboratory tests and numerical simulations are commonly costly and time-consuming, whereas the use of a connectivity metric based on percolation theory can quickly predict fracture permeability, but with relatively low accuracy. For this reason, we selected two static connectivity metrics with the highest and lowest prediction accuracy in previous studies, respectively, and proposed to revise and use them for fracture permeability estimation, considering the effect of isolated large-aperture regions within the fractures under increasing normal stress. Several hundred fractures with different fractal dimensions and mismatch lengths were numerically generated and deformed, and their permeability was calculated by the local cubic law (LCL). Based on the dataset, the connectivity metrics were counted using the revised approach, and the results show that, regardless of the connectivity metrics, the new model greatly improves the accuracy of permeability prediction compared to the pre-improved model, by at least 8% for different cutoff aperture thresholds.

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Section: Fracture Permeability Under Normal Stress From Numerical Sim...supporting

confidence: 94%

Section: Fracture Permeability and Connectivity Metricssupporting

confidence: 78%

Section: Fracture Aperture Generationmentioning

confidence: 99%

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confidence: 99%

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A Connectivity Metrics-Based Approach for the Prediction of Stress-Dependent Fracture Permeability

Deng,

Shang,

2024

Water

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“…The code used here is based on a first principle contact mechanics approach and avoids the assumptions needed in (semi-) analytical approaches or conceptualizations. We investigate a single Carmel mudrock (Kampman et al 2014) sample numerically and experimentally, whose surface was digitized with a digital optical microscope (Keyence 2017; Phillips et al 2021). The numerical investigation is based on a number of randomly selected cross sections used to build 2D models.…”

Section: Introductionmentioning

confidence: 99%

Digital Image-Based Stress–Permeability Relationships of Rough Fractures Using Numerical Contact Mechanics and Stokes Equation

et al. 2022

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Flow in fractures is sensitive to their geometrical surface characteristics. The surface can undergo deformation if there is a change in stress. Natural fractures have complex geometries and rough surfaces which complicates the modelling of deformation and fluid flow. In this paper, we present a computational model that takes a digital image of a rough fracture surface and provides a stress–permeability relationship. The model is based on a first-principle contact mechanics approach at the continuum scale. Using this first principle approach, we investigate numerically the effect of fracture surface roughness and shifting of surfaces on the permeability evolution under applied stress and compare the results with laboratory experiments. A mudrock core fracture surface was digitalized using an optical microscope, and 2D cross sections through fracture surface profiles were taken for the modelling. Mechanical deformation is simulated with the contact mechanics based Virtual Element Method solver that we developed within the MATLAB Reservoir Simulation Toolbox platform. The permeability perpendicular to the fracture cross section is determined by solving the Stokes equation using the Finite Volume Method. A source of uncertainty in reproducing laboratory results is that the exact anchoring of the two opposite surfaces is difficult to determine while the stress–permeability relationship is sensitive to the exact positioning. We, therefore, investigate the sensitivity to a mismatch in two scenarios: First, we assess the stress–permeability of a fracture created using two opposing matched surfaces from the rock sample, consequently applying relative shear. Second, we assess the stress–permeability of fractures created by randomly selecting opposing surfaces from that sample. We find that a larger shift leads to a smaller drop in permeability due to applied stress, which is in line with a previous laboratory study. We also find that permeability tends to be higher in fractures with higher roughness within the investigated stress range. Finally, we provide empirical stress–permeability relationships for various relative shears and roughnesses for use in hydro-mechanical studies of fractured geological formations.

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Flow Characteristics in a 3D-Printed Rough Fracture

Zhang

2022

Rock Mech Rock Eng

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A Systematic Investigation Into the Control of Roughness on the Flow Properties of 3D‐Printed Fractures

Abstract: Fluid transport through rock fractures underlies many natural processes, such as fault rupture (Faulkner et al., 2010), while also influencing hydrocarbon production (

Cited by 30 publications

References 187 publications

A Connectivity Metrics-Based Approach for the Prediction of Stress-Dependent Fracture Permeability

A Connectivity Metrics-Based Approach for the Prediction of Stress-Dependent Fracture Permeability

Digital Image-Based Stress–Permeability Relationships of Rough Fractures Using Numerical Contact Mechanics and Stokes Equation

Flow Characteristics in a 3D-Printed Rough Fracture

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