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148 Part II Gas Drilling Systems

7.2.1 Initiating Gas Drilling
Compressor operators participate in gas drilling routinely. Their general
procedures should be followed because they are familiar with both the local
area and their compressors. To unload an air hole, the cement and cementing
shoe should be drilled out with water or mud, and the cuttings should be
circulated out of the hole. It may take several hours to dry a hole if the hole is
not washed clean. The following procedure should be followed:
1. Go in the hole to the bottom of the casing and pump alternate slugs
of gas to the pressure limit of the compressors and water (do not use
mud) to bring the pressure back down again for further air injection.
2. When most of the water is out of the hole, pump 5 gallons of foaming
agent into the pipe and circulate it around the hole. The detergents
will bring up a large quantity of water.
3. Go to the bottom and repeat this process.
4. Light the blooey line flare or igniter.
5. Drill a little formation and then pick up the pipe past a tool joint.
6. Continue this process until the well begins producing dust.
7. If after 2 hours the well still has not dusted, then
a. Add 5 gallons of 50% foamer/water mixture and start again at
step 4, or
b. Close the rams and pressure up the hole with air, and then open
the rams and let the compressed air blow out of the hole. Then
start again at step 4.
c. Close the radiator shutters on the compressors, or place a piece of
cardboard on the compressor aftercooler to increase the heat of
the air going into the hole.

7.2.2 Initiating Mist Drilling
Misting gas can help hole cleaning, depress downhole fires or explosions,
lower borehole friction, and reduce drill string vibrations. The following
procedure is used to initiate mist drilling:

1. Unload the mud out of the hole as with air drilling but without
attempting to dry the hole.
2. Turn on the mist pump and begin gas circulation. About 1 foot of
formation should be drilled, and the string should be picked up past a
tool joint. Continue this procedure for at least 5 feet. Go to regular mist
drilling if there is no drag on the pickup after 5 feet.