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Calcimator

Decline Curve Calculator

Forecast production decline using exponential or hyperbolic models.

Inputs

bbl/day
%
years

Results

Final Rate

25.5 bbl/day

Cumulative Production

585,751 bbl

Total Decline94.9%
Average Rate160.4 bbl/day
Monthly Decline0.03
How to Use This Calculator
  1. Enter initial production rate (bbl/day) and annual nominal decline rate (%).
  2. Select decline type: exponential (conservative) or hyperbolic, and enter the hyperbolic b factor if applicable.
  3. Enter forecast period (years).
  4. Read EUR (estimated ultimate recovery) and production rate at end of forecast period.
  5. Compare exponential vs. hyperbolic forecasts to understand reserve uncertainty range.

How the result changes with Forecast Period

Forecast PeriodFinal RateCumulative Production
4.90 bbl/day475,413 bbl
155.7 bbl/day609,594 bbl
260.2 bbl/day616,189 bbl
360 bbl/day616,429 bbl

What each input means

Initial Production Rate
Initial production rate at time zero.
Annual Decline Rate
Annual nominal decline rate.
Decline Type
Decline model type. Exponential is conservative.
Hyperbolic b Factor
Hyperbolic exponent (b). Only used for hyperbolic decline.
Forecast Period
Number of years to forecast.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Initial Production Rate = 500, Annual Decline Rate = 30, Decline Type = 0, Hyperbolic b Factor = 1 = 5 input(s) provided
  2. Calculate Final Rate
    Final Rate
    25.5 = 25.5
  3. Calculate Cumulative Production
    Cumulative Production
    585751 = 585751
  4. Calculate Total Decline
    Total Decline
    94.9 = 94.9
  5. Calculate Average Rate
    Average Rate
    160.4 = 160.4

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