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DTH Casing Drilling Tools
Aug 21, 2018

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DTH Casing Drilling Tools


1 Overview

The air DTH hammer and pipe drilling technology uses compressed air as the power, and the pipe drilling tool performs the impact rotary drilling under the action of the air DTH hammer and the drilling machine torque and realizes the synchronous follow-up casing. The final hole heel pipe drilling tool A new technology for drilling in the casing is proposed in the casing.


1.1 Air DTH Hammer and Pipe Drilling Features

It is mainly used for fractured strata which are difficult to form holes, such as gravel layer, flowing sand layer, covering layer, slope layer, etc.; drilling speed is fast and efficiency is high, generally up to 5m/h, dry (air) drilling, right Water-deficient areas, landslide construction that cannot be used for water, etc. are of great significance; casing can be recycled and reused;

Single-stage heel drilling depth is generally 40m, and some can reach more than 80m;

When the ground layer contains a high amount of mud, it is easy to block the pores;

The rig requires low speed (less than 50 rev / min), high torque, preferably long-stroke multi-function drilling rig, water well drilling rig, etc., if the geological drilling rig can slow down.


1.2 Air DTH Hammer and Pipe Drilling Applications

Geological exploration

Earthquake Disaster Management, Emergency Rescue (Chongqing Wulong Landslide Rescue Project)

Water well drilling (Yunnan drought-resistant drilling well project, Shandong drought-resistant drilling well project)

Hydropower Station Construction (High Slope Rehabilitation Project of Yunnan Xiaowan Hydropower Station)

Urban high-rise building foundation treatment

Highway and railway construction project

Tunnel pipe shed construction

Petroleum geophysical drilling and so on.


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GK-4 hole core (partial)




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GK-4 hole core (partial)


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2. Air DTH hammer and pipe drilling work principle

Heel drill structure type

Air DTH hammer and pipe drilling tools are the most important tools for drilling with pipes. At present, there are many types of structures at home and abroad, mainly eccentric, concentric, and right.

There are four types of core and tube drilling tools, and their working principles are different.


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2.1 Air DTH Hammer Eccentricity with Pipe Drilling Principle

The eccentric heel drill has two functions:

1. Can achieve bottom-drilling

2. Synchronous follow-up casing

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2.2 Air DTH Hammer Concentric Drilling Principle

Concentric drill pipe tools must have two functions:

1. Can achieve bottom-drilling

2. Synchronous follow-up casing

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2.3 Air DTH Hammer to the Principle of Drilling

Button Moment: Drilling Rig - Drill Pipe - Impactor - Center Drill Groove - Ring Drill Shoulder; Ring Toner and Pipe Boots are circlip

The purpose of the ring bit rotating without the tube and sleeve rotating.

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2.4 Air DTH Hammer Core Drilling Principle

It is mainly composed of a center core drilling tool and a casing shoe assembly. The drilling tool is provided with an advanced drilling mechanism, an air splitting mechanism, a twisting mechanism, and a transmission to achieve specific functions.

Pressing mechanism, transfer mechanism, coring device.

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2.4 Air DTH Hammer Core Drilling Principle

When drilling, the core and the pipe drilling tool realize the impact rotary drilling, and the core enters the core tube while drilling; the casing is followed up synchronously.

At the end of the drill, the center drill is directly referred to as the core, and the casing is left in the hole.


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