Page 492 - Air and Gas Drilling Manual

The specific weight of the stable foam (mixture of water, surfactant, and air),
mibhx, at the bottomhole pressure and temperature conditions is
w ˙ g w ˙ w Chapter 10: Stable Foam drilling 10-17
mixbh
Q gbh Q w
1 456 11 68
.
.
mixbh
0 583 0 187
.
.
.
17 06 lb/ft 3
mixbh
The density of the stable foam, mixbh , at the bottomhole pressure and temperature is
mixbh
mixbh
g
17 06
.
mixbh
32 2
.
lb sec 2
.
0 530
mixbh 4
ft
2
where g is the acceleration of gravity (32.2 ft/sec ).
The velocity of the foam in the annulus at bottomhole pressure and temperature
conditions, V bh, is
Q gbh Q w
V bh
D h 2 D p 2
4

.
.
0 583 0 187
V bh
.
0 656 2 0 375 2
.
4
.
V bh 338 ft/sec
Using Equation 1-1, the kinetic energy per unit volume at bottomhole pressure
and temperature conditions, KE bh, is