Keynote Lecture: The Role of Drilling Efficiency in Geotechnical Measuring While Drilling-PPT Presentation

PPT Presentation

Pdf Summary

The presentation explains how drilling efficiency is essential to reliable geotechnical measuring while drilling (MWD). It groups drilling parameters into method-based, operator-controlled, and responsive measurements, which together describe how drilling conditions and subsurface materials affect the process. Instrumentation measures depth, rotation, fluid flow and pressure, torque, crowd force, and vibration.<br /><br />An energy-based framework uses specific energy—the mechanical energy input per volume of material removed—to assess drilling performance. Efficient drilling minimizes energy use while supporting effective debris removal, low ground disturbance, and high-quality core recovery. Inefficient drilling may mostly generate friction, while excessive crowding or poor flushing can disturb the material and produce misleading strength estimates.<br /><br />Case studies demonstrate that inefficient drilling, eccentric rotation, and extreme bit wear can cause artificially high specific-energy readings and inaccurate MWD strength estimates. Correcting equipment issues and optimizing drilling procedures improves the stability and reliability of measurements. In rock coring, MWD strength statistics showed close agreement with laboratory core results.<br /><br />The presentation also describes progress in soil and geomaterial characterization. Vibration and strain-wave signatures may help distinguish material types, and new measurements convert time-based sensor data into depth-referenced information. Early comparisons with conventional investigation methods are encouraging, though linking MWD measurements to standard engineering parameters remains a key challenge.<br /><br />Machine-learning results suggest potential for quantitative characterization: reported five-fold cross-validation accuracy was 98.6% ± 1.7%, with strong correlations between MWD predictions and CPT measurements. The broader goal is to advance MWD from a qualitative observation tool into an energy-based system for characterizing soils and rock.

Keywords

drilling efficiency

measuring while drilling

specific energy

geotechnical instrumentation

core recovery

ground disturbance

bit wear

soil characterization

machine learning

CPT measurements