Page 445 - Air and Gas Drilling Manual

Chapter 9: Aerated Fluid Drilling 9-49
determining the Reynolds number at the exit end of this annulus section and
assuming this Reynolds number approximates the flow conditions throughout the
annulus section.
Using Equation 4-11, the approximate specific weight of the gas as it exits this
openhole annulus section is determined from P a4. This is
,
.
( 456 707) ( 1 0)
ga5
.
( 53 36) ( 601 91)
.
.
14 22 lb/ft 3
ga5
Using Equation 1-2, the density of the gas as it exits this annulus section, ga5 , is
.
14 22
ga5
32 2
.
lb sec 2
0 442
.
ga5 4
ft
From Equation 9-7, the kinematic viscosity of the gas at this location, , is
ga5
.
0 000000251
ga5
.
0 442
2
ft
0 000000568
.
ga5
sec
The average kinematic viscosity of the mixture as it exits this annulus section,
, is
ava5
.
.
.
( 1 282)( 0 000000568) ( 31 92)( 0 0002691)
.
ava5
.
1 282 31 92
.
2
.
0 000259 ft /sec
ava5
The approximate average velocity of the aerated drilling fluid as it exits this
annulus section, V a5, is
.
,
.
1 826 6 601 91
19 47)
(. 0 426
.
,
.
456 707 519 67
V a5 % 2 2 &
.
0 656)
4 (. 0 563