Page 422 - Air and Gas Drilling Manual

9-26 Air and Gas Drilling Manual
. 0 656
4
˙ w ˙ w s . 0 949 lb/sec 2 62 .4 . 2 7 60 60 60
s
The total weight rate of flow, ˙ w , in the annulus is
t
˙ w . 1 282 31 .92 . 0 949
t
˙ w 34 .15 lb/sec
t
The absolute viscosity of the drilling mud, m , is

30 cps
m
0
0
(30 ) ( .001 ) ( .2089 )
m
lb sec
0 0006267
.
m 2
ft
Using Equation 1-2, the density of the drilling mud, m , is
75 0
.
m
32 2
.
2
lb sec
.
2 329
m 4
ft
From Equation 9-7, the kinematic viscosity of the drilling mud, m , is
0 0006267
.
m
.
2 329
ft 2
.
0 0002691
m
sec
Surface Return Flow Line
The calculation procedure must be initiated with the known atmospheric
pressure at the exit to the surface return flow line. It is assumed that the drilling
mud and air mixture will exit the well annulus and enter the surface return flow line
at the surface geothermal temperature of 44.74˚F (or 504.41˚R). It is further
assumed that the temperature of the drilling mud and air flow in the surface return
flow line does not change as it flows through the return flow line (i.e., the steel