Page 411 - Air and Gas Drilling Manual

3
Q
0 425 ft /sec
.
a1
In field units, the above is
3 Chapter 9: Aerated Fluid Drilling 9-15
0 425 ( 60) 12
.
q a1
231
q 190 8 gal/min
.
a1
It is necessary to check and see if the above volumetric flow rate did indeed give
laminar flow conditions in the largest annulus cross-sectional area. This is
accomplished by calculating the non-dimensional Reynolds number for this annulus
cross-section and the above volumetric flow rate (with the annulus average fluid
velocity of 1.770 ft/sec). The hydraulic diameter for this annulus cross-section, D hy,
is
8 017 450
.
.
D hy
12 12
.
D hy 0 293 ft
Using Equation 1-2. the drilling mud density, m , is
.
75 0
m
32 2
.
lb sec 2
2 329
.
m 4
ft
The general equation for kinematic viscosity, , is
(9-7)
2
where is kinematic viscosity (ft /sec). The drilling mud effective kinematic
viscosity for laminar conditions is
.
0 0006267
e1
.
2 329
2
0 0002691 ft /sec
.
e1