The use of air as a drilling fluid. In certain types of formations, air drilling is considered a better medium than conventional drilling mud. It is more economical (mud is expensive and the preparation of the slurry and maintaining its condition is time consuming), drilling rates are higher, penetration is faster, and bit life is longer. Although air does a good job of cooling the bit and bringing out the pulverized rock, it has severe limitations. With air drilling, water in the subsurface formations and downhole gas pressure cannot be controlled. When drilling in an area where these two types of intrusions may occur, a mud system must be on standby to avert possible trouble. air drilling a method of rotary drilling that uses compressed air as its circulation medium. This method of removing cuttings from the wellbore is as efficient or more efficient than the traditional methods using water or drilling mud; in addition, of penetration is increased considerably when air drilling is used. However, a principal problem in air drilling is the penetration of formations containing water, since the entry of water into the system reduces its efficiency.
