D Exponent Calculation & Correction Equation
D is an exponent which, relating drilling penetration rate to weight on bit per unit hole diameter, measures the formation's " drillability ". There were several attempts to link the drilling parameters to generate a measure of drillability. The best known was by Jorden and Shirley *, who demonstrated empirically that in homogeneous shale formations, and with all other factors being equal, the drilling penetration rate is proportional to the rotation rate of the drilling bit.
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