...\fracture have strong effects on fracture path and fracture toughness. 1 Introduction As shale gas reservoirs have extremely low permeable and porosity, hydraulic fracturing is commonly used to enhance gas production. Field practices of hydraulic fracturing treatment have shown that shale reservoirs...

... shock, creation and pervasion of fractures between minerals at the surface linked to differences in their light-transmissivity, thermal fatigue. It is possible to show that the critical tensile stress intensity factor (K I ) can be in the same order of magnitude as fracture toughness (K Ic ) which can...

... Abstract Mode-I fracture toughness ( K IC ) quantifies the ability of a material to withstand crack initiation and propagation due to tensile loads. The ISRM has proposed four suggested methods (SR, CB, CCNBD and SCB) for determining K IC , but they present some drawbacks...

... Abstract Estimating the fracture toughness at confining pressure is valuable for a number of practical applications such as hydraulic fracturing used to estimate the in-situ stress or enhance oil and gas extraction from a reservoir, and disposal or safe storage of radiative waste...

... Abstract From the development of Linear Elastic Fracture Mechanics (LEFM) theory, parameters such as fracture toughness, K C , were defined. This parameter describes fracture initiation under a specific loading condition, and is considered the critical value for the stress intensity factor...

... Abstract In this study, two specimen geometries were used to determine the mode-I fracture toughness ( K IC ) of rock: Semi-Circular Bend (SCB) specimens subjected to three-point bending, and pseudo-Compact Tension ( p CT) specimens loaded in pure tension. We discuss the results of a number...

... Abstract The fracture toughness of rock mode I is of great significance for quantitatively evaluating the fracturing ability of shale reservoirs. Based on the cracked chevron notched Brazilian disc test (CCNBD), the mode I (opening-mode crack) fracture toughness of the Longmaxi Formation shale...

... conditions. reservoir characterization fracture prediction expression hydraulic fracturing tensile strength tcd variation reservoir geomechanics notch radius u-shaped notch specimen fracture toughness moleano limestone macael marble application crack-type defect Rock Mechanics...

... the dynamic fracture failure of rocks under various hydrostatic pressures. In this study, a triaxial split Hopkinson pressure bar (SHPB) system is used to measure the dynamic fracture toughness of rocks under five hydrostatic pressures. The results show that dynamic fracture toughness under a certain...

... but with significant scattered in the values of UCS. While Chandler et al. demonstrated for shale the effect of the orientation of fine scale layering relative to loading direction on fracture toughness. They found that layer orientation alone was not sufficient to explain the observed anisotropy in fracture toughness...

...SIZE EFFECT IN FRACTURE TOUGHNESS OF SANDSTONE M. Kataoka, and *Y. Obara Kumamoto University 2-39-1 Kurokami, Chuo-ku Kumamoto, Japan 860-8555 (*Corresponding author: obara@kumamoto-u.ac.jp) Innovations in Applied and Theoretical Rock Mechanics Editors Hassani, Hadjigeorgiou, Archibald ©2015...

... of notch is varied like 40, 42, 44, 45, and 50 deg and FEM analysis shows that the transition from mode-I to Mode-II take place at 49 deg. The same procedure can be extended to find the transition from mode-II to mode-III. KEYWORDS Semi-circular bend test, Fracture toughness, Finite element method (FEM...

... reservoir geomechanics Upstream Oil & Gas contact surface Reservoir Characterization Wellbore Design displacement validity evaluation specimen Modeling & Simulation intensity factor fracture toughness fracture energy dynamic fracture toughness discrete element method...

... rock bursts). Therefore, accurate determination of these fracture parameters is crucial for understanding mechanisms of dynamic fracture and is also beneficial for hazards prevention and mitigation. Various of methods have been proposed in the literature to measure fracture toughness of rocks...

... ABSTRACT In order to investigate the influence of anisotropic characteristics of rock and water vapor pressure of surrounding environment on fracture toughness, a series of Semi-Circular Bend (SCB) tests under various water vapor pressures were performed. The rock used in the test was two...

... applications of SHPB to rocks on the quantification of rock dynamic tensile strength and fracture toughness. 3.1 The split Hopkinson pressure bar SHPB is composed of a striker, an incident bar, and a trans- mitted bar (Figure 4). The impact of a striker bar on the free end of the incident bar induces...

... SCB specimen particle specimen crack propagation hydraulic fracturing fracture toughness Fracture Toughness Testing clumped particle model strength input parameter experiment toughness metals & mining Simulation crack distribution Kimachi sandstone loading roller numerical...

... ABSTRACT The influence of water vapor pressure of surrounding environment on fracture toughness and subcritical crack velocity of rock is clarified from the results of a series of two types of test under various water vapor pressures, namely SCB (Semi-Circular Bend) test and DT (Double torsion...

... ABSTRACT Time-dependent process of crack growth and failure of brittle rock are simulated with the numerical modeling approach using PFC (Particle Flow Code) which can visualize progressive and dynamic behaviors of deformation and failure in time domain.A model of Brazilian fracture toughness...

... ABSTRACT Standard methods to determine fracture toughness which is one of the important factors in rock mechanics were suggested in 1988 and 1995 by the commission on testing methods of ISRM. It is difficult to verify lab test because of the wide variation of test results and difficulty...