Concentric Casing System

Concentric Casing System

Symmetric Overburden Drilling Equipment is suitable for drilling water wells, geothermal wells, short mircopiles,medium mini-type grouting hole of building,damand harbour project.

1. Ring bit and casing shoe assembly is welded to casing prior to drilling. Lock the assembly into pilot bit with hammer. The pilot bit's upper shoulder engages the shoulder of the casing shoe. 

2. Hammer's percussive energy is transferred through the pilot and ring bits, crushing rock . Part of impact energy advances casing. 

3. On completion of drilling and casing , the drill string with pilot bit is retrieved by a slight reverse rotation to unlock the bayonet coupling . The ring bit stays in the hole , and can be recovered only if the casing is retrieved 

4. Drilling continues to the desired depth in the bedrock using a conventional drilling.

Casing drilling involves drilling and casing a well simultaneously through unstable ground conditions, In casing drilling process, down the hole tools can be retrieved, through the casing on wire-line, meaning tool recovery or replacement of tools
can take minutes versus hours under conventional methods. This process employs wire line-retrievable tools and a drill-lock assembly, permitting bit and BHA changes, coring, electrical logging and even directional or horizontal drilling. Once the casing point is reached, the casing is
cemented in place without tripping pipe.
 
Casing drilling has been employed in many countries as an effective method of reducing the overall drilling costs by reducing drilling time and drill string problems
encountered during conventional drilling process.
 
Applications:
Blast holes
Water supply wells
Bridge and building foundations
Standard slant or horizontal drilling
Mining air holes
Environmental monitoring wells
Grouting operations
Seismic shot holes
Soil sample and geotechnical applications
Ground anomaly and tiebacks
Storage caverns and dam
 
Technical Data: