## Convert Pressure into Equivalent Mud Weight

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

# Oilfield Unit

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

Equivalent Mud Weight in 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

# Metric Unit

## Convert pressure in KPa unit into equivalent mud weight in Kg/m3 by using meters as the unit of measurement

Equivalent Mud Weight in Kg/m3 = Pressure in KPa × 1000  ÷ True Vertical Depth (TVD) in meters ÷  9.81

Example:

Pressure = 35,000 KPa
True Vertical Depth = 2,500 meters
Equivalent mud weight, kg/m3= 35,000 × 1,000 ÷ 2,500 ÷ 9.81
Equivalent mud weight, kg/m3= 1,427  kg/m3

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 pressure created by fluid column and 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 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;

True Vertical Depth in ft

Example;

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

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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