# I Progressive Cavity Pump backspin

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1. Feb 15, 2017

### btb4198

I need an equation to give me the backspin speed in HZ and the torque applied to motor from back spin from a given oil well.
The VFD given me the rod torque during forward run. J = 706 lbs-ft. J = F * D
D= 7300 ft = Length of the rod
J = Jm - Jf -Jb +Jten
so I am not sure how to do this ...
can someone help ?
Jten = torque of tension
Jm = torque of the force from the oil
Jb = torque from the backspin hydro brake in the drive head
Jf = torque from the friction on the pcp case
F=MA
M = F/A
M = F/(32.174 ft/s^2)
F = Jf/D
Jm = J + Jb -Jten + Jf
Jb is given in the wellhead doc

but I still need to find t (time)
So, I can get speed of the backspin
I am not too sure
does anyone know ?

Last edited by a moderator: Feb 15, 2017
2. Feb 23, 2017

### Greg Bernhardt

Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.