Page 417 - Air and Gas Drilling Manual

Using Equation 4-11, the specific weight of the gas entering the compressor is
0
1
1
g (,827 ) ( . ) Chapter 9: Aerated Fluid Drilling 9-21
(53 .36 ) (519 . )
67
.
0 0659 lb/ft 3
g
Note the above specific weight value can also be obtained from Figure D-4 in
Appendix D.
The bottomhole pressure, P bh, in absolute pressure is
p bh 3 500 12 685
.
,
p 3 512 685 psia
,
.
bh
P bh p bh 144
2
P bh 505 826 lb/ft abs
,
The temperature of the rock formations near the surface (geothermal surface
temperature) is estimated to be the approximate average year round temperature at
that location on the earth’s surface. Table 4-1 gives 44.74˚F for average year round
temperature for a surface elevation location of 4,000 ft above sea level (for mid
latitudes of North America, or see Appendix D). Therefore, the absolute temperature
of the rock formations at the surface, T r, is
t r 44 74.˚F
.
T r t r 459 67
T 504 41.˚R
r
The depth of the well, H, is
H 10 000 ft
,
The bottomhole temperature, T bh, is

T bh T r 001 H
.
T bh 604 41.˚ R

The borehole average temperature, T av, is