## Convert Pressure into Equivalent Mud Weight

Learn how to convert pressure into equivalent mud weight in PPG as per following formulas.

## 1. Convert pressure in psi  unit into equivalent mud weight in ppg by using feet as the unit of measurement

Equivalent Mud Weight, ppg = pressure in psi ÷ 0.052 ÷ True Vertical Depth (TVD) in ft
Example:
Pressure = 5,000 psi
True vertical depth = 8,000 ft
Equivalent mud weight, ppg = 5,000 psi ÷ 0.052 ÷ 8,000 ft
Equivalent mud weight, ppg = 12.0 ppg

## 2. Convert pressure in psi  unit into equivalent mud weight in ppg by using meters as the unit of measurement

Equivalent Mud Weight in ppg = Pressure in psi ÷ 0.052 ÷ True Vertical Depth (TVD) in meters ÷  3.281

Example: pressure = 5,000 psi
True Vertical Depth = 2,500 meters
Equivalent mud weight, ppg = 5,000 psi ÷ 0.052 ÷ 2,500 m ÷ 3.281
Equivalent mud weight, ppg = 11.7 ppg

Please find the Excel sheet for converting pressure into equivalent mud weight.

Ref book: 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.

## Hydrostatic Pressure Calculation

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/ft3 and feet as the units of True Vertical Depth.

Hydrostatic pressure equation:

Hydrostatic Pressure (HP) = 0.006944 x mud weight, lb/ft3 x TVD, ft

Example: mud weight = 80 lb/ft3 true vertical depth = 10,000 ft
HP = 0.006944 x 80 lb/ft3 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

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.

## 1. Calculate pressure gradient in psi/ft from mud weight in ppg

Pressure gradient in psi/ft = mud weight in ppg x 0.052

Example:
Mud weigt = 9.0 ppg
Pressure gradient in psi/ft = 9.0 x 0.052
Pressure gradient in psi/ft = 0.468 psi/ft

## 2. Calculate pressure gradient in psi/ft  from mud weight in lb/ft3

Pressure gradient in psi/ft = mud weight in lb/ft3 x 0.006944

Example:
Mud weight = 80 lb/ft3
Pressure gradient in psi/ft  = 80 lb/ft3 x 0.006944

OR

Pressure gradient in psi/ft t = mud weight in lb/ft3 ÷ 144

Example:
Mud weight = 80 lb/ft3
Pressure gradient in psi/ft  = 80 lb/ft3 ÷ 144

## 3. Calculate pressure gradient in psi/ft from specific gravity (SG)

Pressure gradient in psi/ft = mud weight in SG x 0.433

Example:
Fluid specific gravity = 2
Pressure gradient in psi/ft = 2.0 x 0.433

## 4. Convert pressure gradient in psi/ft to mud weight in ppg

Mud weight in ppg = pressure gradient in psi/ft ÷ 0.052

Example:
Mud weight in ppg = 0.5 psi/ft ÷ 0.052
Mud weight = 9.615 ppg

## 5. Convert pressure gradient in psi/ft to mud weight in lb/ft3

Mud weight in
lb/ft
3 = pressure gradient in psi/ft ÷ 0.006944

Example:
Mud weight in lb/ft3 = 0.5 psi/ft ÷ 0.006944
Mud weight = 72 lb/ft3

## 6. Convert pressure gradient in psi/ft to mud weight in SG

SG = pressure gradient, psi/ft ÷ 0.433

Example:
SG = 0.5 psi/ft ÷ 0.433
SG = 1.1547

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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