Formation Pressure Gradient Calculator
Calculate pore pressure, fracture pressure, and overburden pressure. Visualize the safe mud weight window vs depth.
Input Parameters
Fracture Gradient (Eaton): Gf = (v/(1-v)) * (Gob - Gpp) + Gpp + Gt
Pore Pressure
--
psi
Fracture Pressure
--
psi
Overburden Pressure
--
psi
Frac Gradient
--
psi/ft
Mud Pressure
--
psi
Mud Weight (EMW)
--
ppg
Safe MW Window
--
ppg
Pressure vs Depth
How this was calculated
Pore Pressure: Pp = Gpp x D, where Gpp is pore pressure gradient and D is depth.
Overburden Pressure: Pob = Gob x D, where Gob is overburden gradient.
Fracture Gradient (Eaton): Gf = (v/(1-v)) x (Gob - Gpp) + Gpp + Gt, where v is Poisson's ratio and Gt is tectonic stress factor.
Mud Pressure: Pm = 0.052 x MW x D, where MW is mud weight in ppg.
Safe MW Window: Between pore pressure equivalent MW and fracture pressure equivalent MW.
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Open Tool →Need help with pore pressure prediction, wellbore stability analysis, or drilling optimization?
Book a free strategy call →Understanding Formation Pressure Gradients
Formation pressure gradients are fundamental to safe and efficient drilling operations. The pore pressure gradient defines the pressure of fluids trapped within the rock matrix, while the fracture gradient determines the pressure at which the formation will break down. The gap between these two gradients defines the safe mud weight window, which is the operating envelope for drilling fluid density.
The Eaton method is one of the most widely used approaches for fracture gradient prediction. It relates the fracture gradient to the overburden gradient, pore pressure gradient, and Poisson's ratio of the rock. In tectonically active regions, an additional tectonic stress factor may be applied. Accurate knowledge of these gradients is essential for casing design, kick detection, and lost circulation prevention.
This calculator uses the Eaton equation to estimate fracture pressure and plots all pressure gradients versus depth, showing the safe mud weight window. All calculations run entirely in your browser. Built by Groundwork Analytics.