Hydrostatic pressure is created by fluid column. Two factors affecting hydrostatic pressure are mud weight and True Vertical Depth. In this article, it will demonstrate how to calculate hydrostatic pressure in different oilfield units.

1. Calculate hydrostatic pressure in psi by using mud weight in pound per gallon (ppg) and feet as the units of True Vertical Depth.

Hydrostatic pressure equation:

**Hydrostatic Pressure (HP) = mud weight in ppg x 0.052 x True Vertical Depth (TVD) in ft**

Example: mud weight = 12.0 ppg

True Vertical Depth = 10,000 ft

HP = 12.0 ppg x 0.052 x 10,000 ft

HP = 6,240 psi

## 2. Calculate hydrostatic pressure in psi by using pressure gradient in psi/ft and feet as the units of True Vertical Depth.

Hydrostatic pressure equation:

**Hydrostatic Pressure (HP) = Pressure gradient in psi/ft x True Vertical Depth (TVD) in ft**

Example: Pressure Ggradient = 0.5 psi/ft

True Vertical Depth = 10,000 ft

HP = 0.5 psi/ft x 10,000 ft

HP = 5,000 psi

## 3. Calculate hydrostatic pressure in psi by using mud weight in lb/ft^{3} and feet as the units of True Vertical Depth.

Hydrostatic pressure equation:

**Hydrostatic Pressure (HP) = 0.006944 x mud weight, lb/ft**^{3} x TVD, ft

Example: mud weight = 80 lb/ft^{3} true vertical depth = 10,000 ft

HP = 0.006944 x 80 lb/ft^{3} x 10,000 ft

HP = 5,555 psi

## 4. Calculate hydrostatic pressure in psi by using mud weight in PPG and meters as unit of True Vertical Depth.

Hydrostatic pressure equation:

**Hydrostatic Pressure (HP) = mud weight, ppg x 0.052 x TVD in meters x 3.281**

Example: Mud weight = 12.0 ppg true vertical depth = 5000 meters

HP = 12.0 ppg x 0.052 x 5000 x 3.281

HP = 10,237 psi

**Download the Excel sheet for calculating hydrostatic pressure**

**Ref books: **Lapeyrouse, N.J., 2002. Formulas and calculations for drilling, production and workover, Boston: Gulf Professional publishing.

Bourgoyne, A.J.T., Chenevert , M.E. & Millheim, K.K., 1986. SPE Textbook Series, Volume 2: Applied Drilling Engineering, Society of Petroleum Engineers.

Mitchell, R.F., Miska, S. & Aadny, B.S., 2011. Fundamentals of drilling engineering, Richardson, TX: Society of Petroleum Engineers.

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