Hydrostatic pressure is pressure created by fluid column and two factors affecting hydrostatic pressure are mud weight and True Vertical Depth.
You can read full details about hydrostatic pressure from this article, Understand Hydrostatic Pressure.
In this article, it will demonstrate how to calculate hydrostatic pressure in different oilfield and metric unit.
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) = 0.052 × Mud Weight × True Vertical Depth (TVD)
Where;
Mud Weight in ppg
True Vertical Depth in ft
Example;
Mud Weight = 12.0 ppg
True Vertical Depth (TVD) = 10,000 ft
Hydrostatic Pressure (HP) = 0.052 × 12.0 × 10,000
Hydrostatic Pressure (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 × True Vertical Depth (TVD)
Where;
Pressure gradient in psi/ft
True Vertical Depth in ft
Example;
Pressure Gradient = 0.5 psi/ft
True Vertical Depth (TVD) = 10,000 ft
Hydrostatic Pressure (HP) = 0.5 psi/ft × 10,000 ft
Hydrostatic Pressure (HP) = 5,000 psi
3. Calculate hydrostatic pressure in psi by using mud weight in lb/ft3 and feet as the units of True Vertical Depth.
Hydrostatic pressure equation:
Hydrostatic Pressure (HP) = 0.006944 × Mud Weight × True Vertical Depth (TVD)
Where;
Mud Weight in lb/ft3
True Vertical Depth in ft
Example;
Mud Weight = 80 lb/ft3
True Vertical Depth (TVD) = 10,000 ft
Hydrostatic Pressure (HP) = 0.006944 × 80 lb/ft3 × 10,000 ft
Hydrostatic Pressure (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 × 0.052 × TVD in meters x 3.281
Where;
Mud Weight in ppg
True Vertical Depth in meter
Example:
Mud Weight = 12.0 ppg
True Vertical Depth (TVD) = 5000 meters
Hydrostatic Pressure (HP) = 12.0 × 0.052 × 5000 × 3.281
Hydrostatic Pressure (HP) = 10,237 psi
5. Calculate hydrostatic pressure in Pascal by using mud weight in kg per cu-meter (kg/m3) and meter (m) as the units of True Vertical Depth.
Hydrostatic Pressure (HP) = 9.81 × Mud Weight × True Vertical Depth (TVD)
Where;
Mud Weight in kg/m3
True Vertical Depth in meter
Example;
Mud Weight = 1,000 kg/m3
True Vertical Depth (TVD) = 100 m
Hydrostatic Pressure (HP) = 9.81 × 1,000 × 100
Hydrostatic Pressure (HP) = 981,000 pascal
6. Calculate hydrostatic pressure in bar by using mud weight in kg per cu-meter (kg/m3) and meter (m) as the units of True Vertical Depth.
Hydrostatic Pressure (HP) = 9.81 × Mud Weight × True Vertical Depth (TVD) ÷ 100,000
Where;
Mud Weight in kg/m3
True Vertical Depth in meter
Example;
Mud Weight = 1,000 kg/m3
True Vertical Depth (TVD) = 100 m
Hydrostatic Pressure (HP) = 9.81 × 1,000 × 100 ÷ 100,000
Hydrostatic Pressure (HP) = 9.81 bar
7ุ. Calculate hydrostatic pressure in atm by using mud weight in kg per cu-meter (kg/m3) and meter (m) as the units of True Vertical Depth.
Hydrostatic Pressure (HP) = 9.81 × Mud Weight × True Vertical Depth (TVD) × 9.8692 × 10-6
Where;
Mud Weight in kg/m3
True Vertical Depth in meter
Example;
Mud Weight = 1,000 kg/m3
True Vertical Depth (TVD) = 100 m
Hydrostatic Pressure (HP) = 9.81 × 1,000 × 100 × 9.8692 × 10-6
Hydrostatic Pressure (HP) = 9.6817 atm
Download Free Excel Spread Sheet
Download the Excel sheet for calculating hydrostatic pressure – This is 2020 update with Metric Unit
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.
