# d-Exponent Calculator

Enter value and click on calculate. Result will be displayed.
d=([log R/[60×N]]/[log [12×W]/[1000×D]])×(ρ_n/ρ_m)^c
R = Penetration Rate      N = Rotary Speed
W = Weight on Bit      D = Drill Bit Diameter
ρn = Mud Weight Equivalent      ρm = Mud Weight Used
C = Shale Compactibility Coefficient

Penetration Rate:
Ft / Hr
Rotary Speed:
Rev / Minute
Weight on Bit:
1000 Lb
Drill Bit Diameter:
Inches
Mud Weight Equivalent:
Lb / Gal
Mud Weight Used:
Lb / Gal
Shale Compactibility Coefficient:

Result:

d-Exponent:
d-Exponent Calculator

This concept was first developed by Jordan and Shirley as a factor in evaluating drilling rates and predicting abnormal pore pressure zones.

All things being equal, the d-index should increase with depth when drilling in the normal pressure range. A reversal of this trend is when drilling indicates potential overpressure.

Example of use
Input data: Permeability: 10Ft/Hr; Rotation speed: 20Rev/Minute; Weight on bit: 20 1000 Lb; Bit diameter: 10Inches; Mud equivalent: 60Lb/Gal; Mud weight: 40Lb/Gal; Mudstone compaction coefficient: 6

Click "Calculate", d index: 14.6211

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