This articles demonstrates how to determine pressure losses through drill string.
To determine pressure drop while the drilling mud is passing through a circular pipe (drill pipe and drill collar), you can calculate pressure loss with the following equation:
Assumptions:
Turbulent viscosity = 3 cp
Friction factor = 0.378(Q/D)-0.14
The first equation has a coefficient (C) to take into account the friction and the geometry of the bore ID.
Where:
P = pressure loss, psi
L = length of pipe, ft
W = mud density, ppg
Vf = viscosity correction factor
PV = plastic viscosity, centipoises
Q = flow rate, gpm
Di = inside diameter of pipe, inch
C = general coefficient for internal diameter of pipe
Determine the pressure loss in the drill string based on the following information
Drill pipe length = 5000 ft
ID of drill pipe = 3.34 inch
Drill collar length = 500 ft
ID of drill collar = 2.8 inch
Mud Weight = 9.5 ppg
Plastic Viscosity = 12 centipoise
Flow rate = 600 gpm
Pressure loss in the drill string composes of two parts which are pressure loss in drill pipe and drill collar.
We can write the relationship like this:
Pt = Pdp + Pdc
Where; Pt = total pressure loss in drill string
Pdp = pressure loss in drill pipe
Pdc = pressure loss in drill collar
Determine pressure loss in drill pipe with following steps:
Pdp = 1254
Determine pressure loss in drill collar with following steps:
Pdc = 295
Pt = 1254 + 295 = 1,549 psi
Total pressure loss in the drill string equates to 1,549 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.
Hi,
The above formula is valid for all units?, for example the MW in sg and length of DP in meter, can we still use the above formula to calculate the pressure loss in drill pipe?
Thanks.
Luis
This is specially for oilfield unit. If you want to calculate pressure loss in the drill string, please follow the following equation. Pressure Losses Through Drill String Calculation
i think this advance step i need the first step
because i’m training
please help me
Thanks & Best Regards