Workover Assistant
Help Document
This handy app is for the field personnel who work a lot with workover rigs on
various types of wells. The calculations it provides are those most commonly used
during well workovers.
To calculate Hydrostatic Pressure, the formula is as follows:
fluid/mud weight in pounds per gallon multiplied by 0.052 multiplied by true
vertical depth in feet, or pressure gradient in psi/ft multiplied by true vertical
depth in feet
ex: 10.2 x 0.052 x 7600 = 4031 or 0.5304 x 7600 = 4031
To calculate Formation Pressure, the formula is as follows:
hydrostatic pressure in drill string as psi plus shut in drill pipe pressure as psi
ex: 4031 + 200 = 4231
To calculate Initial Circulating Pressure, the formula is as follows:
slow circulating rate (SCR) as psi plus shut in drill pipe pressure as psi
ex: 150 + 200 = 350
To calculate Final Circulating Pressure, the formula is as follows:
slow circulating rate (SCR) as psi multiplied by kill mud weight as pounds per
gallon divided by current mud weight (CMW) as pounds per gallon
ex: 150 x 10.4 / 10.2 = 153
To calculate Test Pressure, the formula is as follows:
(equivalent mud weight as pounds per gallon minus current mud weight as
pounds per gallon) multiplied by 0.052 multiplied by shoe true vertical depth as
feet ex: (10.4 - 10.2) x 0.052 x 7600 = 79
To calculate Max Allowable Annular Surface Pressure (MAASP), the formula is as
follows:
(max allowable mud weight as pounds per gallon minus current mud weight as
pounds per gallon) multiplied by 0.052 multiplied by shoe true vertical depth as
feet
To calculate Pressure Gradient, the formula is as follows:
mud weight as pounds per gallon multiplied by 0.052, OR, pressure as psi divided
by true vertical depth as feet
To calculate Pressure Drop Per Foot (when tripping dry pipe, the formula is as
follows:
(mud weight as pounds per gallon multiplied by 0.052 multiplied by pipe
displacement as barrels per foot) divided by (casing capacity as barrels per foot
minus pipe displacement as barrels per foot)
To calculate Pressure Drop Per Foot (when tripping wet pipe, the formula is as
follows:
(mud weight as pounds per gallon multiplied by 0.052 multiplied by (pipe
displacement as barrels per foot) plus pipe capacity as barrels per foot)) divided
by (casing capacity as barrels per foot minus pipe displacement as barrels per foot
minus pipe capacity as barrels per foot)
To calculate Internal Capacity, the formula is as follows:
inside diameter (ID)^2 / 1029.4
To calculate Annular Capacity, the formula is as follows:
(inside diameter (ID)^2 - outside diameter (OD)^2) / 1029.4
To calculate PIpe Displacement. the formula is as follows:
(outside diameter (OD)^2 - inside diameter (ID)^2 / 1029.4 OR pipe weight in
pounds per foot / 2747
To calculate Mud Weight, the formula is as follows:
gradient as psi per foot divided by 0.052 or hydrostatic pressure as psi divided by
0.052 divided by true vertical depth as feet
To calculate Kill Mud Weight, the formula is as follows:
shut in drill pipe pressure (SIDPP) as psi divided by 0.052 divided by true vertical
depth as feet plus current mud weight (CMW) as pounds per gallon
To calculate Max Allowable Mud Weight (MAMW), the formula is as follows:
pressure (at the shoe) in psi divided by 0.052 divided by true vertical depth as feet
at test depth
To calculate Equivalent Mud Weight, the formula is as follows:
(pressure as psi divided by 0.052 divided by true vertical depth as feet) plus
current mud weight as pounds per gallon
To calculate Kill String Length, the formula is as follows:
Disclaimer: By downloading, accessing or using Kelly Gayneaux apps or any page of our apps
you signify your assent to this disclaimer. The contents of our apps, including without limitation
all data, information, text, graphics, links and other materials are provided as a convenience to
our app users and are meant to be used for informational purposes only. We do not take
responsibility for decisions taken by the reader based solely on the information provided in any
of our apps.