Page 462 - Air and Gas Drilling Manual

9-66 Air and Gas Drilling Manual
537 66.˚R
T
av1
In order to obtain the approximate value of the Fanning friction factor for
Equation 6-82, it is necessary to estimate the Reynolds number and, thus, the flow
conditions inside the drill pipe body lumped geometry along H 1. This is
accomplished by determining the Reynolds number at the entrance end of the inside
of this drill string section and assuming this Reynolds number approximates the
flow conditions throughout the inside this drill string section.
Using Equation 4-11, the approximate specific weight of the gas as it enters this
drill string section is determined from P in. This is
( 381 868) ( 1 0)
,
.
gi1
( 53 36) ( 537 66)
.
.
13 31 lb/ft 3
.
gi1
Using Equation 1-2, the density of the gas as it enters this drill string section, ,
gi1
is
13 31
.
gi1
32 2
.
lb sec 2
.
0 413
gi1 4
ft
From Equation 9-7, the kinematic viscosity of the gas at this location, gi1 , is
0 000000251
.
gi1
.
0 413
2
ft
.
0 000000606
gi1
sec
The average kinematic viscosity of the mixture as it enters this drill string section,
, is
avi1
.
.
.
.
( 1 282)( 0 000000606) ( 31 92)( 0 0002691)
avi1
1 282 31 92
.
.
2
0 000259 ft /sec
.
avi1
Using the inside diameter of the drill pipe tool joints, D 7, the approximate
average velocity of the aerated drilling fluid as it enters the drill string section, V i1, is