Well Control Training - Conversion factor .052Well Control Training - Conversion factor .052

A Well Control Training Manual extract
  • A Convertion Factor Well Control Training extract, taken from the Fearnley Procter Well Control course manual.

The Conversion Factor of 0.052, used in Well Control calculations

The pressure exerted by a column of fluid depends on its density (weight) and vertical height or depth (the fluid width or shape has no bearing on the pressure). In well control the hydrostatic column is our primary method of control. To find the pressure exerted at any point in the wellbore, we can use the following hydrostatic pressure formula

Hydrostatic Pressure (psi) = Mud Weight (ppg) x 0.052 x Depth (ft)  

Following, is an explanation of why we use the conversion factor 0.052
We use this for all our well control calculations to maintain BHP and control of the well.

  • 1 cubic foot contains 7.48 U.S. gallons
  • A fluid weighing 1 ppg would weigh 7.48 pounds per cubic foot
  • The pressure exerted by one foot height of fluid over the area of the base would be:

    $ \dfrac{7.48\text{ (lbf)}}{\text{144 }(in^2)} = \text{0.0519 psi (rounded to 0.052)} $

  • Therefore, a one foot high column of 1 ppg fluid would exert 0.052 psi on its base.
  • 0.052 is the pressure gradient, psi/ft, of  1 lbf/gallon fluid.

Conversion Factors For Other Mud Weight Units

  • Specific Gravity (mud weight) x 0.433 = psi/ft (pressure gradient)
  • Pounds per cubic foot (mud gradient) ÷ 144 = psi/ft (pressure gradient)
  • Kilogrammes per cubic metre x 0.00044 = psi/ft (pressure gradient)
  • The last equation may be easier to use when written as:
    Kilogrammes per cubic metre ÷  2262 = psi/ft  (pressure gradient)