Page 273 -

Appendix B – Minimum Gas Flow Rates 237

3500
Minimum Required Air Injection Rate (scfm) 2500 Q =4 bbl/hour
3000

2000
w
1500
Q =8 bbl/hour
w
Q =12 bbl/hour
w
1000
Q =16 bbl/hour
w
w
500
Q =24 bbl/hour
w
For cuttings removal
0 Q =20 bbl/hour
0 2000 4000 6000 8000 10000 12000 14000 16000
Depth (ft)
Figure B.7 Calculated air injection requirements for drilling a 6¼-in hole with a 2⅞-in
drill pipe at an ROP of 60 ft/hr (water-air interfacial tension = 60 dynes/cm).

3500
Minimum Required Air Injection Rate (scfm) 2500 Q =4 bbl/hour
3000

2000

w
1500
Q =8 bbl/hour
w
Q =12 bbl/hour
w
1000
Q =16 bbl/hour
w
w
500
Q =24 bbl/hour
w
For cuttings removal
0 Q =20 bbl/hour
0 2000 4000 6000 8000 10000 12000 14000 16000
Depth (ft)
Figure B.8 Calculated air injection requirements for drilling a 6¼-in hole with a 2⅞-in
drill pipe at an ROP of 120 ft/hr (water-air interfacial tension = 60 dynes/cm).