Particle jet impact deep-rock in rotary drilling: Failure process and lab experiment

Area of Science:

• Engineering
• Geology
• Materials Science

Background:

• Deep-well drilling in hard rock strata faces challenges with low drilling speeds and difficult rock fragmentation.
• Conventional drilling methods are often inefficient in these demanding geological conditions.

Purpose of the Study:

• To introduce and evaluate particle waterjet coupled impact rock-breaking technology for rotary drilling in deep wells and hard rock.
• To address the technical limitations of current drilling methods.

Main Methods:

• Established acceleration and damage models for particle jets impacting rock.
• Investigated particle acceleration mechanisms and dynamic rock damage evolution.
• Developed an experimental device for particle jet coupled impact rock-breaking in rotary drilling.
• Analyzed the influence of jet parameters on penetration depth and failure volume through experiments and numerical simulations.

Main Results:

• Rock damage and pit formation increase over time, with damage evolving radially.
• Drilling speed was observed to double with particle jet impact compared to conventional drilling.
• Optimal nozzle layouts with impact angles of 8° and 20° demonstrated rapid rock drilling capabilities.
• Numerical simulation methods were validated against experimental findings.

Conclusions:

• Particle waterjet coupled impact technology offers a substantial improvement in drilling efficiency for hard rock formations.
• The developed experimental device and analysis provide valuable insights for practical engineering applications in deep-well drilling.