Page 424 - Air and Gas Drilling Manual

9-28 Air and Gas Drilling Manual
lb sec
0 000000251
.
g
2
ft
Using Equation 1-2, the density of the gas, g , is
0 0659
.
g
.
32 2
lb sec 2
0 002046
.
g 4
ft
From Equation 9-7, the kinematic viscosity of the gas, g , is
.
0 000000251
g
0 002046
.
ft 2
.
0 000123
g
sec
The kinematic viscosity of the aerated drilling fluid (the mixture of the drilling
mud and the compressed air) can be approximated with an average kinematic
viscosity term. This average kinematic viscosity term can be approximated by
weight averaging the separate viscosities with the weight rates of flow of the separate
fluids. Therefore, the average kinematic viscosity at the exit end of the surface return
flow line, sr , is
w ˙ g g w ˙ m m
(9-12)
sr
w ˙ g w ˙ m
The average kinematic viscosity at the exit end of the surface return flow line, , is
sr
0
( .282 )( .000123 ) (31 .92 )( .0002691 )
0
1
sr
. 1 282 31 .92
2
0 000263 ft /sec
.
sr
The average velocity of the aerated drilling fluid (the mixture of the drilling
mud and the compressed air) as the mixture exits the end of the surface return flow
line into the atmosphere, V , is
sr