Measuring Gypsum Rock Strength While Coring with a Laboratory Rock Core Driller-PPT Presentation

PPT Presentation

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The study evaluated whether measurements collected during laboratory rock coring could be used to estimate the unconfined compressive strength (UCS) of gypsum, potentially reducing reliance on costly, time-consuming UCS tests that provide only discrete results.<br /><br />Researchers developed a laboratory measurement-while-drilling (MWD) system to record thrust, torque, penetration rate, and rotational speed. Strain gauges mounted on a removable coupler measured thrust and torque, while a string potentiometer and Hall-effect sensor measured penetration rate and rotational speed. The sensors were calibrated, and gypsum samples were cored under dry and saturated conditions. Cores were then prepared and tested for UCS.<br /><br />The team used the MWD data to calculate two compound parameters: specific energy and drillability. Both showed strong linear correlations with gypsum UCS in dry and saturated conditions, with correlation coefficients (R) ranging from 0.83 to 0.96. Specific energy provided slightly stronger correlations than drillability in both conditions.<br /><br />These results suggest that laboratory coring measurements, particularly specific energy, may offer a practical means of estimating gypsum strength while drilling.

Keywords

gypsum

unconfined compressive strength

measurement while drilling

specific energy

drillability

laboratory coring

UCS estimation

thrust and torque

penetration rate

rock mechanics