For power head rig, from up to down: taps, power head, air box, double-wall drill pipe and bottom drilling tools.
For turn plate rig, from up to down: double-channel air-water taps, double-wall drill pipe initiative, the double-wall drill pipe and bottom drilling tools.
The bottom drilling tools has different types as follow:
a. packer + forward-reverse transition connector + DTH hammer +bit
b. Through DTH hammer
c. Diversion connector + tri-cone bit (or blade bit, PDC bit)
2 The process principle
For example the power head rig, compressed air through the air box into the annular gap of the double-wall drill pipe and reach the bottom drilling tools, and carrying debris from the inner tube back. we can inject right amount of foam agent in compressed air, further improve its ability to carry devries back.
3 technical characteristics:
a. Compare with normal circulation drilling, due to rock debris back quickly from the inside pipe, ability to carry rock debris, hole bottom clean, thus greatly improve the drilling efficiency;
b. With less even no water, especially for drilling in the dry and loss formation to drilling.
c. If use the outside flat double-wall drill pipe, we can solve some problems, for example drilling in Collapse the bottom, ravelly ground and Shrinkage strata.
d.Can be air, air atomization,air bubbles,foam slurry,slurry or water as flushing media, it is a drilling technology with multi-process and multi-media.
e. According to the characteristics of the formation and flushing media, we can use all kinds types of drill bits to do.
4 Applicable range:
a. Suitable for including for complex ground of drilling wells.
b. Suitable for including for complex formation of solid deposits drilling.
c. Suitable for soft coal seam gas drainage well drilling.
d. Suitable for drilling in Shale gas well.
e. Suitable for all with the prsitive cycle is difficult to drilling in the formations.