Page 242 - Air and gas Drilling Field Guide 3rd Edition

9.4 Nonfriction and Friction Illustrative Examples 233

The bottom hole pressure in absolute pressure is
p bh ¼ 2317:39 þ 8:749
2
p bh ¼ 2329:14 N=cm abs
P bh ¼ P bh 10000
2
P bh ¼ 23261410:0N=m 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 5-1 gives 7.08 C for average year-

round temperature for a surface elevation location of 1219.1 m above sea level
(see Appendix B). Therefore, the absolute temperature of the rock formations
at the surface is

t r ¼ 7:08 C
T r ¼ t r þ 273:15
T r ¼ 280:23 K:
The depth of the well is
H ¼ 3048 m:

The bottom hole temperature is
T bh ¼ T r þ 0:018 H
T bh ¼ 334:96 K:
The borehole average temperature is
280:23 þ 334:96
T av ¼
2
T av ¼ 307:60 K:
The open hole diameter is

d h ¼ 200:0 mm
d h
D h ¼
1000
D h ¼ 0:200 m:
The estimated drilling rate of penetration is 60 ft/hr. The weight rate of flow of
solids from the advance of the drill bit is

p 2 k
_ w s ¼ D ð 9810:0Þ S s (9-8)
4 h ð 60Þ 60Þ
ð

18:3
p 2
_ w s ¼ ð 0:200Þ ð 9810:0Þ 2:7Þ
ð
4 ð 60Þ 60Þ
ð
_ w s ¼ 4:222 N=sec: