d exponent calculator

enter the value and click "calculate", the calculation result will be displayed.
`d=([log R/[60×N]]/[log [12×W]/[1000×D]])×(ρ_n/ρ_m)^c `
r = permeability n = rotational speed
w = bit weight d = drill diameter
ρn = mud weight equivalent ρm = weight of mud used
c = shale compaction coefficient

enter a value:

penetration rate:
Ft / Hr
speed:
Rev / Minute
weight on bit:
1000 Lb
drill bit diameter:
Inches
mud weight equivalent:
Lb / Gal
mud specific gravity:
Lb / Gal
shale compaction coefficient:

calculation result:

d index:
d-index calculator

this concept was first proposed by jordan and shirley as a factor in evaluating drilling rates and predicting areas of abnormal pore pressure.

all things being equal, the d-index should increase with depth when drilling within the normal pressure range. this trend reverses when drilling reveals potential overpressure.

usage example
input data: permeability: 10ft/hr; rotation speed: 20 rpm; weight on bit: 20 1000 pounds; drill bit diameter: 10 inches; mud equivalent: 60lb/gal; mud weight: 40lb/gal; mudstone compaction factor: 6

click "calculate", d index: 14.6211

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