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Table 4 Results of the analytical approach for breakouts

From: Borehole damaging under thermo-mechanical loading in the RN-15/IDDP-2 deep well: towards validation of numerical modeling using logging images

Name Principal stress in the 2D plane perpendicular to the well Breakout characteristics
Pwell = 0 MPa Pwell = 34 MPa
σA* (MPa) σB* (MPa) σ90°, R = r (MPa) rθ = 90°, σθ = UCS (cm) σ90°, R = r (MPa) rθ = 90°, σθ=UCS (cm)
Case A 76 134 326 14.8 292 13.6
Case B 60 79 175 < R 141 < R
Case C 76 178 459 23.0 425 21.0
Case D 80 94 200 < R 166 < R
  1. The computation of the borehole potential damage is linked to no to low wellbore fluid pressure (Pwell). σ90°, R = r is the circumferential stress at the wellbore boundary in the direction of the minimal 2D stress, rθ = 90°, σθ = UCS is the distance from the wellbore center where the circumferential stress is equal to the UCS of the dolerite (214 MPa), in the direction of the minimal 2D stress, R is the radius of the borehole. Principal stresses in the cross section perpendicular to the well are obtained by diagonalization of the stress state (σss, σdd, τsd) mentioned in Table 1 and are thus slightly different from horizontal principal stresses