Symmetric Overburden Casing Drilling Systems

SINODRILLS Symmetric Overburden Casing Drilling Systems

Casing drilling, or casing while drilling (CWD) process, is a concept that combines two time-consuming processes, drilling and casing, together, performing them at the same time. During the CWD process, powered by a DTH hammer, a central piloting bit drives a ring bit to drill a hole wide enough for a casing tube to slide down; drilling and casing processes are therefore performed at the same time.

Symmetric is a system comprised of an ingeniously simple concentric method of drilling through overburden with casing.  Symmetric can drill straight holes at any angle (including horizontal) and to depths beyond 100 meters. Working together as one efficient drill bit, the components are made up of:

• A pilot bit with large internal flushing holes and external flushing grooves.

• Symmetrical ring bit (reamer) with internal bayonet coupling

• Casing shoe for driving of casing.

• The pilot bit is attached to any common DTH hammer shank or top hammer rod thread.

The casing shoe is welded to the casing. The pilot bit and ring bit are locked together by the bayonet coupling. They drill a hole large enough to allow the casing to be pulled into the hole. The pilot bit and ring bit rotate with the drill string, while the casing shoe and casing do not rotate. When the required depth is reached, the pilot bit is unlocked by a slight reverse rotation of the drill string. The drill string and pilot bit will be retrieved through the casing, the ring bits and casing shoe will be left in the hole for a permanent casing system. Also, the ring bits and casing can be retrieved through the special design of the ring bits and casing shoe. We can manufacture both permanent Symmetric and Retrievable Symmetric systems, which can meet your comprehensive requirements.

Features of Symmetric Overburden Casing Drilling Systems

• Complete types of drilling tools suitable for casing tubes with various diameters;

• Good stability and reliability granted by premium alloy steel material and fine CNC manufacturing process;

• Cost-effectiveness realized by mass production.

Applications of Symmetric Overburden Casing Drilling Systems

Water well drilling, geothermal well drilling, foundation piling, geological prospecting, etc.

Permanents of Symmetric Overburden Casing Drilling Systems

1.  When starting drilling, the central bit drives the ring set to drill a hole wide enough for the casing tube to slide down.

2.  When arriving at the bedrock, reverse the rotation of the tools and pull out the central bit from the hole, leaving the ring set in the hole.

3. Pour concrete and proceed to the next steps.

Retrievable

1.  When start drilling, the central bit drives the ring set to drill a hole wide enough for casing tube to slide down.

2.  When arriving the bedrock, reverse rotation of  the drill string and pull out the central bit from the hole.

3.  Pull the casing tube out with the ring set while pouring concrete.

Structure of Eccentric Overburden Casing Drilling Systems