STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

970 Drilling and Well Completions
Equations
1. Hydrostatic pressure is
P, = 0.052 y* z
(4-205)
where P, = hydrostatic pressure in psi
y = mud specific weight in lb/gal
z = depth in ft
2. Turbulent flow pressure loss in pipe (Equation 4-187) is
where AP = pressure loss in psi
AL = pipe length in ft
y = fluid specific weight in Ib/gal
v = average fluid velocity in ft/s
m = fluid viscosity in cp
d = pipe ID in in.
with
v = w(2.448 x d2)
where Q = flowrate in gal/min
d = pipe ID in in.
3. Turbulent flow pressure loss in annulus (Equation 4-188) is
where (notations same as above) d, = borehole or casing diameter in in.
d, = pipe OD in in.
4. Flowrate through a choke, or nozzle, or leak (Equation 4-186) is
Solution
where Q = flowrate in ft3/s
C = coefficient (0.95 to 1.0)
g, = acceleration of gravity (32.17 ft/s2)
AP = pressure loss in psi
y = fluid specific weight in Ib/ftJ
A = area in ft2
1. AP drillpipes: 1,590 psi
AP bit nozzles: 718 psi
AP annulus: 74 psi