DTH Odex bit

When drilling in loose, unconsolidated so-called overburden formations, It is difficult to retrieve the drill strings after the hole has been drilled, the bore hole is often lost before a casing tube can be inserted to support it, currently there are Eccentric and Concentric two types of Overburden drilling systems represent the latest technology in simultaneous casing advancement.

Eccentric casing drilling system or called Odex by Atlas copco and TUBEX by Sandvik, which enables you to drill and case deep holes simultaneously in all types of formation, even those with large boulders. Casing diameters from 89 mm (ODEX 76) to 273 mm (ODEX 240) can be used, this method is based on a pilot bit and eccentric reamer, which together drill a hole slightly larger than the external diameter of the casing tube. This enables the casing tube to follow the drill bit down the hole.

ODEX drilling Steps:

1). When drilling starts, the ODEX reamer swings out and reams the pilot-hole wide enough for the casing tube to slide down behind the drill bit assembly.

2). When the required depth is reached, rotation is reversed carefully, whereupon the reamer swings in, allowing the drill bit assembly to be pulled up through the casing.

3). Casing tubes that are to be left in the drill hole should be sealed at the bottom of the hole by means of cement grout or some other sealing agent.

4). Drilling continues to the desired depth in the bedrock using a conventional drill strings.