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Geomechanics and FracturingIn-Situ Stress and Rock Mechanics

Fracture Gradient - Zoback and Healy Calculator

Shmin=(1+μf2+μf)−2(Sv−Pp)+PpS_{hmin} = (\sqrt{1 + \mu_f^2} + \mu_f)^{-2}(S_v - P_p) + P_p

Enter the stress and pressure terms required by the model. The calculator returns fracture gradient in the declared unit system.

Tabular solver

Inputs

Defaults provide a quick field-unit example for the equation.

3 variables

Calculation runs locally with the shared TypeScript engine.

Formula reference

Fracture gradient estimates the pressure gradient required to initiate or propagate a fracture under a stated stress model.

View formula, units, and source

Assumptions

  • The selected stress model is appropriate for the local geologic setting.
  • Input stress and pore-pressure values are representative at depth.
  • Units are consistent across pressure and gradient terms.

Common mistakes

  • Using a generic stress model without local calibration.
  • Mixing gradient and pressure units.
  • Treating screening results as operational limits without review.