Method Ben Eaton Method

where S/D = overburden gradient, psi/ft

Pf/D = formation pressure gradient at depth of interest, psi/ft y = Poisson's ratio

Procedure:

  1. Obtain overburden gradient from "Overburden Stress Gradient Chart."
  2. Obtain formation pressure gradient from electric logs, density measurements, or from logging operations.
  3. Obtain Poisson's ratio from "Poisson's Ratio Chart."
  4. Determine fracture gradient using above equation.
  5. Determine fracture pressure, psi: psi = F x D
  6. Determine maximum mud density, ppg: ppg = F - 0.052

Example: Casing setting depth = 12,000 ft Formation pore pressure = 12.0 ppg

  1. Determine S/D from chart = depth = 12,000 ft S/D = 0.96 psi/ft
  2. Pf/D = 12.0 ppg x 0.052 = 0.624 psi/ft
  3. Poisson's Ratio from chart = 0.47 psi/ft
  4. Determine fracture gradient: F = (0.96 — 0.6243) (0.47 - 1 — 0.47) + 0.624

F = 0.336 x 0.88679 + 0.624 F = 0.29796 + 0.624 F = 0.92 psi/ft

  1. Determine fracture pressure: psi = 0.92 psi/ft x 12,000 ft psi = 11,040
  2. Determine maximum mud density: ppg = 0.92 psi/ft
  3. 052 ppg = 17.69
+3 -2

Responses

  • Protasio
    How poisson ratio use in fracture gradient calculation?
    2 years ago
  • Nadine Grunwald
    How to use EATON's equation?
    1 year ago

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