Study on mode II fracture initiation using the strain energy density criterion

Penelitian ini bertujuan untuk mencari arah perpanjangan dan perambatan retak,tegangan kritis atau dimensi retak kritis dan stabilitas jalur retakdikenakan mode kombinasi I dan pemuatan mode II. Model yang dinilairetak ciri dengan kombinasi mode yaitu Stres Tangensial Maksimum(MTS) dan Strain Energy Density (SED). Model-model tersebut diacu diterapkan padapiring kasus dengan panjang yang tak terbatas untuk inisiasi, pertumbuhan retak, dan stres kritisdikenakan biaksial, ketegangan dan kompresi). Hasil analisis juga diverifikasidengan hasil yang memuat dengan sudut retak (telah diperoleh dari percobaansebelumnya.

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Replacing conventional brittleness indices determination with new attributes employing true hydrofracturing mechanism

Interpretation ◽

10.1190/int-2019-0103.1 ◽

2020 ◽

pp. 1-62

Author(s):

Ritesh Kumar Sharma ◽

Satinder Chopra ◽

Larry R. Lines

Keyword(s):

Fracture Toughness ◽

Energy Density ◽

Hydraulic Fracturing ◽

Seismic Data ◽

Strain Energy Density ◽

Strain Energy ◽

Fracture Initiation ◽

Low Permeability ◽

Well Log ◽

Core Data

Shale resource plays are associated with low permeability, and hence hydraulic fracturing is required for their stimulation and production. Even though considerable non-uniqueness exists in identifying favorable zones for hydraulic fracturing, geophysicists seem to be avid followers of Rickman et al. (2008)’s, brittleness criteria of low-Poisson’s ratio and high-Young’s modulus, proposed a decade ago. In this study, we highlight the fallacy in following such a criterion for any shale play and propose a new attribute that makes use of strain energy density and fracture toughness. While the former controls fracture initiation, the propagation of fractures is governed by the latter. As hydraulic fracturing comprises both these properties, it is firmly believed that the new proposed attribute could be used to highlight the favorable intervals for fracturing. Core data, well-log curves along with mud-logs have been used to authenticate the proposed attribute. Finally, the computation of the new attributes is implemented on the seismic data and encouraging results are observed.

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Evaluating the Applicability of Fracture Criteria to Predict the Crack Evolution Path of Dolomite Based on SCB Experiments and FEM

Mathematical Problems in Engineering ◽

10.1155/2013/959806 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Cunbao Li ◽

Lingzhi Xie ◽

Li Ren ◽

Heping Xie ◽

Jun Wang

Keyword(s):

Energy Density ◽

Poisson’S Ratio ◽

Strain Energy Density ◽

Strain Energy ◽

Poisson's Ratio ◽

Mode I ◽

Mode Ii ◽

Pure Mode ◽

Fracture Criteria ◽

Fracture Surfaces

Mixed mode fracture tests are conducted under various initial loading combinations of mode I and mode II (from pure mode I to pure mode II) on semicircular bend (SCB) specimens of dolomite rock. Damage zones are observed behind the fracture surfaces of the broken samples. Scanning electron microscope images of the fracture surfaces are used to study the failure manner. Using the conventional remesh method based on the finite element method (FEM), several widely accepted fracture criteria are employed to theoretically predict the fracture paths. These criteria include the maximum tangential stress criterion, minimum strain energy density criterion, maximum energy release rate criterion, maximum dilatational strain energy density criterion, and the distortional strain energy density criterion. The applicability of the five fracture criteria is examined. The results show that none of the criteria are successful in predicting the crack trajectories of the predominately mode II cracks; the differences among the predicted results of the crack growth paths are negligible for each crack inclined angle. The effect of Poisson’s ratio on the fracture criteria is also investigated and the results show that the predicted crack trajectories are not sensitive to Poisson’s ratio.

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