Optical visualization of strain development and fracture propagation in laminated rocks

Nath, Fatick; Mokhtari, Mehdi

doi:10.1016/j.petrol.2018.04.020

Cited by 40 publications

(9 citation statements)

References 19 publications

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“…Therefore, the effect of the paint was considered negligible on the displacement properties of the sample. Nath and Mokhtari [23] described the procedure for creating the speckle pattern in the rock sample face.…”

Section: Rock Specimen Formation Permeability (Md) Porosity (%)mentioning

confidence: 99%

“…When the deformation of both reference and target subset centers was obtained, the maximum similarity was attained in the deformed image. For details of the DIC technique and working principle, interested readers can explore the relevant literature of different researchers [21,23,25].…”

Section: Deformation Measurement Using a Digital Image Correlation Mementioning

confidence: 99%

“…When researchers had been trying to solve these complex failure processes using traditional methods, optical techniques provided several additional advantages [21][22][23], such as identifying fracture generation and propagation, strain measurement, and monitoring of rock deformation under loading condition.…”

Section: Introductionmentioning

confidence: 99%

“…Mokhtari et al [22] applied this method to characterize the fracture initiation and propagation on naturally fractured rock. Similarly, application of DIC was extended to characterize the deformation behaviors in sandstone and carbonates rocks [29,30], laminated shale [23,31], Buda limestone [32], and Mancos shale [33].…”

Section: Introductionmentioning

confidence: 99%

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Analyzing the Validity of Brazilian Testing Using Digital Image Correlation and Numerical Simulation Techniques

et al. 2020

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Characterizing the mechanical behavior of rocks plays a crucial role to optimize the fracturing process in unconventional reservoirs. However, due to the intrinsic anisotropy and heterogeneity in unconventional resources, fracture process prediction remains the most significant challenge for sustainable and economic hydrocarbon production. During the deformation tracking under compression, deploying conventional methods (strain gauge, extensometer, etc.) is insufficient to measure the deformation since the physical attachment of the device is restricted to the size of the sample, monitoring limited point-wise deformation, producing difficulties in data retrieval, and a tendency to lose track in failure points, etc. Where conventional methods are limited, the application of digital image correlation (DIC) provides detailed and additional information of strain evolution and fracture patterns under loading. DIC is an image-based optical method that records an object with a camera and monitors the random contrast speckle pattern painted on the facing surface of the specimen. To overcome the existing limitations, this paper presents numerical modeling of Brazilian disc tests under quasi-static conditions to understand the full-field deformation behaviors and finally, it is validated by DIC. As the direct tensile test has limitations in sample preparation and test execution, the Brazilian testing principle is commonly used to evaluate indirectly the tensile strength of rocks. The two-dimensional numerical model was built to predict the stress distribution and full-field deformation on Brazilian disc under compression based on the assumptions of a homogenous, isotropic and linear elastic material. The uniaxial compression test was conducted using the DIC technique to determine the elastic properties of Spider Berea sandstone, which were used as inputs for the simulation model. The model was verified by the analytical solution and compared with the digital image correlation. The numerical simulation results showed that the solutions matched reasonably with the analytical solutions where the maximum deviation of stress distribution was obtained as 14.59%. The strain evolution (normal and shear strains) and displacements along the central horizontal and vertical planes were investigated in three distinguishable percentages of peak loads (20%, 40%, and 90%) to understand the deformation behaviors in rock. The simulation results demonstrated that the strain evolution contours consistently matched with DIC generated contours with a reasonable agreement. The changes in displacement along the central horizontal and vertical planes showed that numerical simulation and DIC generated experimental results were repeatable and matched closely. In terms of validation, Brazilian testing to measure the indirect tensile strength of rocks is still an issue of debate. The numerical model of fracture propagation supported by digital image correlation from this study can be used to explain the fracturing process in the homogeneous material and can be extended to non-homogeneous cases by incorporating heterogeneity, which is essential for rock mechanics field applications.

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Section: Rock Specimen Formation Permeability (Md) Porosity (%)mentioning

confidence: 99%

Section: Deformation Measurement Using a Digital Image Correlation Mementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analyzing the Validity of Brazilian Testing Using Digital Image Correlation and Numerical Simulation Techniques

et al. 2020

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“…Hence, horizontal/vertical or shear strains could be measure by consequent images of the surface and could be corresponded to loading. Using this technique, a virtual extensometer could be put on any direction and strain could also be measured at that direction [21,22]. Several researchers have used this DIC technique to study the strain development and propagation in different types of interlayers on pavements.…”

Section: Digital Image Correlation (Dic)mentioning

confidence: 99%

Experimental Evaluation of Engineered Cementitious Composites as Reflective Crack Control Interlayer for Composite Pavements

et al. 2019

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Reflective cracking at transverse joints is considered as a predominant distress in composite pavements. Various interlayers have been used previously to prevent or retard reflective cracking. Engineered cementitious composite (ECC) is a special type of high-performance fiber-reinforced cementitious material that is expected to perform better as an interlayer due to its higher tensile strength and ductility. This study aims to evaluate the effectiveness of ECC as an interlayer system experimentally. A laboratory test protocol was designed to simulate repeated traffic loads to measure the fatigue performance of ECC interlayer system using digital image correlation (DIC) technique. It was found that the composite pavement specimens with ECC interlayer provided significantly higher fatigue life as compared to the control specimens without interlayer. This result indicates that ECC could be used as a potential effective interlayer system to retard or mitigate reflective cracking.

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Constraints of sedimentary structures on key parameters of shale gas reservoirs: A case study of the Wufeng and Longmaxi formations of the Ordovician‐Silurian transition in Luzhou area, Sichuan Basin, southwestern China

et al. 2021

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There are various sedimentary structures developed in the black shales of the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation in Luzhou area, southern Sichuan Basin, southwestern China. In order to evaluate the controlling effects of sedimentary structures on the key parameters of shale reservoir properties, collected classification of sedimentary structures, scanning electron microscope observation, analysis of shale fabric and porosity characteristics, lowpressure nitrogen adsorption, methane isothermal adsorption, and conventional triaxial compression test were carried out based on shale samples from Wells A-H1, B-H1, C-H1 and D-H1 in the study area. The sedimentary structures recorded in these shales are categorized into five types: homogeneous bedding, weak horizontal bedding, strong horizontal bedding, discontinuous ripple bedding, and gravel-bearing massive bedding. In general, the palaeo-hydrodynamics and oxygen content of water columns were weak when homogeneous bedding shale was deposited. The organic matter is the most abundant and the total organic carbon content is up to 4.01% on average. The average quartz content is 43.5%, and the brittleness index is the highest. The porosity and adsorption capacity were the highest, with an average of 4.57% and 79.5 scf/ton, respectively. Combined with its mechanical properties of low Poisson's ratio and high Young's modulus, homogeneous bedding sedimentary structure is associated with the shale units possessing the highest organic matter abundance, the strongest reservoir property, and the best fracability, which is the priority target for exploration and development of the Wufeng to lower Longmaxi Formation in the Sichuan Basin, southwestern China.

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Optical visualization of strain development and fracture propagation in laminated rocks

Cited by 40 publications

References 19 publications

Analyzing the Validity of Brazilian Testing Using Digital Image Correlation and Numerical Simulation Techniques

Analyzing the Validity of Brazilian Testing Using Digital Image Correlation and Numerical Simulation Techniques

Experimental Evaluation of Engineered Cementitious Composites as Reflective Crack Control Interlayer for Composite Pavements

Constraints of sedimentary structures on key parameters of shale gas reservoirs: A case study of the Wufeng and Longmaxi formations of the Ordovician‐Silurian transition in Luzhou area, Sichuan Basin, southwestern China

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