Geomechanics and Ground Control · Geomechanics · 1 mark · Numerical answer
Hydraulic fracturing is used in rock with tensile strength6 MPa and minor principal stress8 MPa. Borehole breakdown pressure is10 MPa. Neglect pore-pressure effects. Find the major principal stress in MPa to two decimals.
The ideal vertical-borehole relation is Pb=3σ₃−σ₁+T. Rearranging gives σ₁=3σ₃+T−Pb=3×8+6−10=20 MPa. The tensile-strength term must be included in breakdown pressure.
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