Page 459 - Air and Gas Drilling Manual

Inside the Drill String (7,000 ft to Surface)
The second drill string section increment is denoted by the length H 2. The
temperature at the bottom of the drill pipe tool joints lumped geometry in the cased
section is Chapter 9: Aerated Fluid Drilling 9-63
T 2 574 41.˚R
The average temperature of the drill pipe tool joints lumped geometry along H 2 and,
thus, the temperature of the aerated fluid flow inside the this drill string length is
T av2 572 66.˚R

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 tool joints lumped geometry along H 2. 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 i1. This is

,
.
( 405 216) ( 1 0)
gi2
.
.
( 53 36) ( 572 66)
.
13 26 lb/ft 3
gi2
Using Equation 1-2, the density of the gas as it enters this drill string section, gi2 ,
is
.
13 26
gi2
32 2
.
lb sec 2
.
0 412
gi2 4
ft
From Equation 9-7, the kinematic viscosity of the gas at this location, , is
gi2
.
0 000000251
gi2
.
0 412
ft 2
.
0 000000609
gi2
sec