A down-the-hole drill, usually called DTH by most professionals, is basically a jackhammer screwed on the bottom of a drill string. The fast hammer action breaks hard rock into small cuttings and dust that are evacuated by a fluid (air, water or drilling mud). The DTH hammer is one of the fastest ways to drill hard rock. The system is thought to have been invented independently by Stenuick. Origin of the nameDTH is short for “down-the-hole”. Since the DTH method was originally developed to drill large-diameter holes downwards in surface-drilling applications, its name originated from the fact that the percussion mechanis. .
In DTH drilling, the percussion mechanism – commonly called the hammer – is located directly above the drill bit. The drill pipes transmit the necessary feed force and rotation to the hammer and the bit, along with the flui.
[pdf] This Handbook is a description of the complex process that comprises drilling a geothermal well. The focus of the detailed Chapters covering various aspects of the process (casing design, cementing, logging and instrumentation, etc) is on techniques and. .
The audience for this Handbook is assumed to be familiar with the general nature of drilling, so there is no attempt to give procedures and guidance for every step needed to drill a. .
This Handbook was funded by the US Department of Energy’s Geothermal Technologies Program and has been made possible with support and guidance from Jay Nathwani.. .
The word "geothermal" comes from the combination of the Greek words gê, meaning Earth, and thérm, meaning heat. Quite literally.
[pdf] This Handbook is a description of the complex process that comprises drilling a geothermal well. The focus of the detailed Chapters covering various aspects of the process (casing design, cementing, logging and instrumentation, etc) is on techniques and. .
The audience for this Handbook is assumed to be familiar with the general nature of drilling, so there is no attempt to give procedures and guidance for every step needed to drill a. .
This Handbook was funded by the US Department of Energy’s Geothermal Technologies Program and has been made possible with support and guidance from Jay Nathwani.. .
The word "geothermal" comes from the combination of the Greek words gê, meaning Earth, and thérm, meaning heat. Quite literally.
[pdf] 
