... results in wide scatter in their ultimate strength and the so-called size effect. This paper proposes an approach based on s (SVEs) to characterize rock fracture strength at the mesoscale. The use of SVEs ensures that the material randomness is maintained upon averaging of microscale features. Because...

... defects and inhomogeneity. In the approach, microcracks with certain statistics are incorporated in the computational domain. In the approach, fracture strength values are sampled using a Weibull probability distribution. We use the Mohr-Coulomb failure criterion to define an effective stress...

... microscale features similar to RVEs, and provide a more economical solution approach than those methods that explicitly model all microcracks in rock. To create a random field for macroscopic fracture strength field, we first generate several realizations of rock with a prescribed crack density...

... the stochastic nucleation parameters and the alternative definitions of the effective stress. 1 INTRODUCTION hydraulic fracturing strength reservoir geomechanics Upstream Oil & Gas criteria mohr-coulomb model fraction Reservoir Characterization Wellbore Design criterion damage model...

...). An example is given in Fig. 1. That is, in general, the differential stress for fracture strength of a particular rock is approximately the same at the same “effective confining pressure” when the latter is taken to be the total confining pressure minus the pore pressure. In addition to that, according...

... should be included in the simulations for their stability assessments. complex reservoir Engineering hydraulic fracturing element method crack density fracture strength microcrack fracture network Upstream Oil & Gas strength heterogeneity hydraulically crack tip spatial mesh...

... stress ranging from 57 to 100% of their estimated fracture strength. Strain was measured parallel and normal to the core axis. Samples loaded to stresses of 80 to 100% of the estimated fracture stress failed in times of 2 to 3.6 × 10 5 sec. Samples stressed to less than 80% of their estimated fracture...

... best-fit line mode ii university kartchner cavern subcritical crack growth parameter fracture strength escabrosa limestone coconino sandstone hydraulic fracturing upstream oil & gas fracture toughness intercept stress rate specimen Abstract An on-going project...

... Abstract In this paper, statistical aspects of the constant stress-rate test were investigated. The effects of the number of specimens on the subcritical crack growth parameters were examined. The grooved disk specimens were used to determine the fracture strength. 7 groups of fictitious data...

... strength and the ratio of the mode II fracture toughness to the mode I fracture toughness is equal to 1.8. not require the measurement of a crack velocity or a crack length. The constant stress-rate test uses the relation between the fracture strength and applied stress rate. The constant stress-rate test...

... Reservoir Characterization Wellbore Design hydraulic fracturing strength mode ii test crack growth parameter stress intensity factor Loading Rate specimen reservoir geomechanics Upstream Oil & Gas fracture toughness mode II loading ii subcritical crack growth parameter...

...DYNAMIC FRACTURE STRENGTH OF OIL SHALE UNDER TORSIONAL OAD I NG by J. Lipkin and A.K. Jones, Sandia Laboratories This paper was presented at the 20th U.S.Symposium on Rock Mechanics, held in Austin, Texas, June 4-6, 1979. The material is subject to correction by the author. Permission to copy...

... into tension, initiating fracture and fragmentation. The early studies of Rinehart¹ have shown that the dynamic fracture strength of rock can exceed the static strength by as much as one order of magnitude. This observation has been substantiated by later studies and has attained fairly wide acceptance...

... hydraulic fracturing cyclic loading Artificial Intelligence strength Zoback Hoshino dilatancy wellbore integrity Upstream Oil & Gas sandstone Byerlee Wellbore Design North Carolina Dunn porosity fracture strength journal geophysical research Consulting Engineer dilation...

... strength diameter flaw dynamic tensile strength arkansas novaculite experiment Coalescence novaculite hydraulic fracturing Rock mechanics fracture strength fracture surface high rate tensile load Upstream Oil & Gas size distribution specimen fracture stress history...

... hydraulic fracturing cylinder metals & mining strength Seam II fracture strength reservoir geomechanics coal plane uniaxial condition loading Reservoir Characterization Upstream Oil & Gas cleavage plane specimen laboratory strength elastic strain energy loading cycle...

... ABSTRACT The model which Birkimer has developed to explain the increase in fracture strength of brittle, rock-like materials with increasing rate of loading may have some applicability. It should be noted that since his analysis presupposes elastic behavior he could equally well express his...

...DEPENDENCE OF FRACTURE STRENGTH OF ROCKS ON GRAIN SIZE by WILLIAM F. BRACE, Research Fellow Dunbar Laboratory, Harvard University Cambridge, Massachusetts INTRODUCTION The Griffith theory 6'7 forms the basis of most analyses of brittle fracture. Griffith himself sug- gested its application to rocks...