Page 388 - Air and Gas Drilling Manual

Chapter 8: Air, Gas, and Unstable Foam Drilling 8-71
3. With the air turned on and flowing to the well, and it has been
determined that the gas is wet, no drilling should be carried out since
rock flour and cuttings will likely form mud rings. With air on, raise
and lower the drilling string with the drill string rotating at
approximately 100 rpm to smash up existing mud rings and prevent
formation of new mud rings.
4. If the gas is wet (with water or distillate), begin the injection of water
and additives (given in Table 8-1) into the injected air flow. Use Figure
8-16 as a guideline to determine the amount of water to be injected into a
vertical well. Begin to drill with unstable foam circulation fluid. (Note
an alternative is to switch to natural gas, industrial nitrogen, or inert
atmospheric as the circulation gas.)

Figure 8-17: Guideline for water injection (with foam drilling additives) to suppress
ignition of downhole hydrocarbons (for vertical boreholes with hydrocarbon bearing
formations of approximately 200 ft or less).