Drill Bit Life

Summarize completed bit lives, pooled cost/meter and caller linear-wear scenario; censored bits and nonlinear wear are excluded.

Description

Completed drill-bit histories give observed life lengths and a pooled cost per drilled metre.

Completed drill-bit histories give observed life lengths and a pooled cost per drilled metre. A remaining-wear fraction creates a simple linear estimate from the mean observed life.^[1]

The tool returns meanObservedLifeMeters, pooledBitCostPerMeter, estimatedRemainingMeters. The computation uses supplied observations and parameters rather than acquiring measurements.

When to use Drill Bit Life

Use this for the following task: Summarize completed bit lives, pooled cost/meter and caller linear-wear scenario; censored bits and nonlinear wear are excluded. Prepare observations and calibration parameters on the same unit and reporting basis.

How to use Drill Bit Life and understand its results

Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
Enter drilledMetersByBit, bitCosts, remainingWearFraction according to the field table, then run the tool.
Read meanObservedLifeMeters, pooledBitCostPerMeter, estimatedRemainingMeters. Use the calculation below to interpret the selected mean or the model’s signs, units and comparison flags.
Review the supplied assumptions and calibration before comparing or reporting the result.

Input field	Meaning	Value type and bounds	Requirement
drilledMetersByBit	Drilled meters by bit	list of number	Required
bitCosts	Bit costs	list of number	Required
remainingWearFraction	Remaining wear fraction	number	Required

Provide aligned nonempty lists of positive completed drilling lengths and nonnegative costs, plus a remaining-wear fraction in [0,1].

mean life = Σmetres/bitCount; pooled cost/metre = Σcost/Σmetres; remaining = mean life×wearFraction

The symbols and boundary conditions refer to the supplied fields and the implementation described above.

Output field	Meaning	Value type
meanObservedLifeMeters	Mean observed life meters	number
pooledBitCostPerMeter	Pooled bit cost per meter	number
estimatedRemainingMeters	Estimated remaining meters	number

json

{
  "input": {
    "drilledMetersByBit": [
      100,
      200,
      300
    ],
    "bitCosts": [
      50,
      70,
      90
    ],
    "remainingWearFraction": 0.25
  },
  "output": {
    "meanObservedLifeMeters": 200,
    "pooledBitCostPerMeter": 0.35,
    "estimatedRemainingMeters": 50
  }
}

Limitations and assumptions

Partly used or right-censored bits need another analysis. Linear wear is a supplied scenario and does not model rock changes, failure modes or individual bit condition.

Numerical inputs must be finite. Input-shape and calculation checks do not establish measurement quality or the validity of a supplied calibration.

Alternative or Complementary methods

Choose Core Recovery Percentage when you need its operation: Compute run and length-weighted total core recovery from all recovered material; distinct from RQD intact-piece length filtering. Choose Joint Volume Jv for the complementary operation: Calculate Jv as reciprocal normal spacings plus random-joint frequency; conventional Jv units are m⁻¹ despite its name, with no assumed RQD conversion.

Background reference: Measures of scale: sample variance and standard deviation.

References

Measures of scale: sample variance and standard deviation — NIST/SEMATECH

Similar or alternative tools

Core Recovery Percentage
Compute run and length-weighted total core recovery from all recovered material; distinct from RQD intact-piece length filtering.
Joint Volume Jv
Calculate Jv as reciprocal normal spacings plus random-joint frequency; conventional Jv units are m⁻¹ despite its name, with no assumed RQD conversion.