STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

836 Drilling and Well Completions
Frlction Pressure Loss Calculations
Laminar Flow
For pipe flow of Bingham plastic type drilling fluid, the following can be used:
FLV ZL
Ap = P +y
1500d' 225d
Corresponding equation for a Power law type drilling fluid is
AP = [(?)( $31 "KL
(4-1 06)
(4- 107)
For annular flow of Bingham plastic and Power law fluids, respectively,
Ap = FPLV + ZYL
1000(d, - d,)' 200(d, - d,)
(4-108)
and
Ap = [( ](%)I" (d, 2.4v -4)
KL
300( d, - d, )
(4-109)
Turbulent Flow
Turbulent flow occurs if the Reynolds number as calculated above exceeds a
certain critical value. Instead of calculating the Reynolds number, a critical flow
velocity may be calculated and compared to the actual average flow velocity [60].
The critical velocities for the Bingham plastic and Power law fluids can be
calculated as follows:
Bingham plastic fluid
v, =
1.08~~ +l.OSJp; +9.256(d, -d,)'Zyp
(dl -4)
(4-110)
Power law fluid
(4-111)
In the case of pipe flow, for practical purposes, the corresponding critical
velocities may be calculated using Equation 4-110 and 4-111, but letting d, = 0.