... applications. If the confining stress variation between rock layers represents one of the main reasons for fracture containment at depth, a contrast of fracture toughness can also lead to fracture containment. Fracture toughness contrasts are presents at different scales. They are due to lithological changes...

..., density, water absorption, and compressive strength, were investigated. The mode I fracture toughness of the ceramics was assessed by subjecting a notched semi-circular bending (NSCB) specimen to three-point bending loading. The full-field strains on the surface of the specimens were measured using...

... international journal tensile crack speed different rock type propagation fracture toughness upstream oil & gas mining science hydraulic fracturing zhang geological subdiscipline crack speed wang engfracmech gauge crack propagation velocity ARMA 23 0602 How Fast Can Tensile Cracks Propagate...

... of 14% was prepared, and using a cylindrical mold, specimens were cast and then cured at 70 °C. Mode II fracture toughness, the evolution of the crack tip opening and sliding displacement and the shear and minimum principal strain behavior were examined through strain mapping using the Digital Image...

... that the resistance to fracturing, expressed in the dislocation model by the required force and in the FEM by an effective fracture toughness that increases with fracture extension tending to asymptotic value, depends strongly on the fracture propagation direction. A dominant parameter that quantifies these effects...

... propagation journal pipe torque equation directional drilling coefficient wob fracture accident upstream oil & gas drillstring design concentration coefficient formula mpa china university relationship fracture toughness engineering diameter extended-reach drilling ARMA 22 0541...

... ABSTRACT: Pressurizing a jacketed and notched borehole under confinement is a laboratory test used for the estimation of rock fracture toughness. The premise is that the fracture toughness can be calculated based on the critical burst pressure obtained by the experiments. Recent advances have...

... accentuating Mode I fracture toughness over viscous fluid effects, compared to the field. Subsequently, a set of laboratory parameters is proposed at a higher gelatin concentration (18-to-19%-by-weight), yielding improved scalability against field operations, minimizing the difference between the lab-scale...

... at an appropriate resolution is the key for successful prediction fracture growth and other crucial treatment parameters. Our focus is on studying several strategies to average fracture toughness and assess their suitability for use in advanced computational methods such as FE/BEM. In practice the well log...

.... In contrast, the FPZ is smaller in glutenite of strong cementation and sandstone. The fracture development and size of FPZ are also related to fracture toughness. The lower the fracture toughness is, the lower the load ratio and the larger the FPZ are. Therefore, cementation between the gravel and matrix has...

... additional parameters, namely the critical fracture energy per unit of area ( G c ) and length scale parameter ( ℓ ). G c describes the energy consumed to form the unit length of fractures, which is related to fracture toughness ( K c ). The fracture toughness can be easily captured by ISRM suggested...

... the VDR and TDR. The "jump" phenomena have been observed in the TDR caused by high fracture toughness. The displacement of fracture location and asymmetrically dynamic propagation are affected by the distribution of rock elastic modulus. These results also indicate that the hydraulic fracture propagation...

...ARMA 21-1605 A Reinterpretation of Fracture Toughness From Fluid In- jection Testing Gao, Yue Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, MN, U.S.A. Eve, Robin bp P&O, U.K. Heller, Robert bp I&E, U.S.A. Ispas, Ion Department of Petroleum Engineering, Texas...

... "reservoir" zones. Subsequently, a detailed mechanical characterization was carried out on core plugs taken from each of these zones. Results show nominally "ductile" zones are weaker in terms of UCS, tensile strength, fracture toughness, and confined compressive strength. However, by a variety...

.../tailings ratio of 22% and cured with a slightly elevated temperature at 72±2 , for seven days. Thereafter, the cylindrical specimens were cut into semi-circular specimens and a series of semi-circular bending tests were performed. The mode I fracture toughness, KIC, of the geopolymer was obtained...

... confining pressure, and the plastic characteristics of rocks increase with the increase of confining pressure, and the increase range of plastic characteristics of different rocks also has obvious difference. The tensile strength and fracture toughness of different rocks vary greatly, the tensile strength...

... FPZ, fully developed FPZ, and fracture growth. The experimental results show that the full developed FPZ length of Wufeng shale is 372 and the critical opening displacement is 0.671 The mode I fracture toughness measured by millimeter- scale shale specimen is 1.858 MPa m, which is 60~69% higher than...

... reservoir geomechanics structural geology hydraulic fracturing shale gas upstream oil & gas siltstone strength sandstone strain energy scda fracture toughness specimen reservoir characterization complex reservoir cumulative energy particle connected fracture network...

... formations were initiated under tensile loading (Mode I), progressed into a mixed tensile-shearing loading (Mode I + Mode II) at intermediate loading, and finally shearing loading (Mode II) at higher loading. The fracture toughness approximation is then presented. Only Mode-II fracture were identified...

... textures. Specifically, micro-structural variations in grain sizes and bonding strengths inside each layer may introduce a higher degree of anisotropy. There is a wide range of variability of laboratory-measured fracture toughness of natural rock specimens because of micro-structural textures. However...