Keynote Lecture: DPM Depth-time Algorithm for Eliminating the Random Variations in MWD Penetration Rate-Paper

Paper

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The paper presents a DPM (Drilling Process Monitoring) depth–time algorithm to address random fluctuations in penetration rates measured by MWD (Measurement While Drilling). MWD systems typically calculate penetration rate over preset depth intervals and output it as a depth series. These rates can vary substantially—even in relatively uniform ground—making it difficult to identify strata and their boundaries reliably.<br /><br />DPM instead records drilling parameters as real-time data throughout the full drilling process. Its algorithm isolates the periods when the bit advances into new material, excluding pauses and other operations. It then plots bit depth against net drilling time. The authors interpret stable, approximately straight sections of this curve as homogeneous strata: each section’s gradient represents its constant penetration rate, and changes in gradient indicate stratum boundaries.<br /><br />The study applies this approach both to DPM records and to existing MWD data. In a Cambridge University borehole dataset from London, the algorithm identified seven main zones and 41 subzones. The inferred zoning was reported to compare well with known lithological units. For one MWD interval, a linear fit to the depth–time curve had a correlation coefficient of 0.9998, yielding a stable rate of 2.153 m/min despite strong fluctuations in the original penetration-rate record.<br /><br />The authors conclude that the algorithm can remove apparent random variation from MWD penetration-rate data and improve the detection of ground layers and interfaces. They also suggest that combining inferred penetration rates and stratum thicknesses with drilling-power measurements could support assessment of material strength. The method is presented as applicable to several drilling systems, including hydraulic rotary and air-driven percussive-rotary equipment.

Keywords

DPM

drilling process monitoring

depth-time algorithm

MWD

measurement while drilling

penetration rate

stratum boundaries

lithological units

borehole data

ground layer detection