A DTH drill pipe has two major jobs in pneumatic water well drilling: transmitting mechanical loads and delivering compressed air to the downhole hammer.
But the return path of that air is equally important.
After operating the hammer, exhaust air carries broken rock upward through the space between the drill string and borehole wall.
This space is commonly called the annulus.
If the relationship between pipe diameter and hole diameter is unsuitable, cuttings transport can become less efficient.
Poor hole cleaning may contribute to:
Cuttings falling back
Repeated crushing of broken rock
Reduced penetration
Increased bit wear
Higher risk of stuck drilling tools
As borehole diameter increases, the drill bit removes a greater volume of rock.
The air system must move these additional cuttings toward the surface.
Therefore, the following should be considered together:
Drill pipe outside diameter
Borehole diameter
Bit diameter
Compressor airflow
Hammer requirements
Drilling depth
Formation characteristics
Choosing a smaller drill pipe only because it is lighter may change the return-air conditions.
Likewise, selecting a larger pipe without checking the hammer, rig and borehole geometry may create other compatibility problems.
As the borehole becomes deeper, cuttings must travel a greater distance before reaching the surface.
Maintaining effective flushing therefore becomes increasingly important.
YKDRILL supplies DTH water well drill pipes in multiple diameters for different rigs, hammers and borehole sizes.
The most effective drill string is one in which the drill pipe, hammer, bit, compressor and borehole geometry work together as a complete air-drilling system.
