General considerations for drill system design

Drilling systems are discussed in general terms, component functions common to all systems are identified, and a simple classification is drawn up in order to outline relations between penetration, material removal, hole wall support, and ground conditions. Energy and power requirements for penetration of ice and frozen ground are analyzed for both mechanical and thermal processes. Power requirements for removal of material and for hoisting of drill strings are considered, and total power requirements for complete systems are assessed. Performance data for drilling systems working in ice and frozen ground are reviewed, and results are analyzed to obtain specific energy values. Specific energy data are assembled for drag-bit cutting, normal impact and indentation, liquid jet attack, and thermal penetration. Torque and axial force capabilities of typical rotary drilling systems are reviewed and analyzed. The overall intent is to provide data and quantitative guidance that can lead to systematic design procedures for drilling systems for cold regions.