Production Decline Calculator
Analyze production decline using Arps decline curve methods (exponential, hyperbolic, harmonic)
Input Parameters
Enter initial production data and decline parameters
Arps Decline Types
- Exponential (b=0): Constant % decline, most conservative
- Hyperbolic (0<b<1): Declining % decline, most common
- Harmonic (b=1): Slowest decline, often for water drive
Results
Enter values and click Calculate to see results
Formula Reference
Arps Decline Equations
The general Arps hyperbolic decline equation:
q(t) = qi / (1 + b * Di * t)^(1/b)
Where:
q(t) = Production rate at time t
qi = Initial production rate
Di = Initial decline rate (nominal)
b = Hyperbolic exponent (0 <= b <= 1)
t = Time
Exponential Decline (b = 0)
q(t) = qi * e^(-Di * t)
Cumulative Production:
Np(t) = qi / Di * (1 - e^(-Di * t))
EUR (as t -> infinity):
EUR = qi / Di
Hyperbolic Decline (0 < b < 1)
q(t) = qi / (1 + b * Di * t)^(1/b)
Cumulative Production:
Np(t) = qi^b / ((1-b) * Di) * (qi^(1-b) - q(t)^(1-b))
Harmonic Decline (b = 1)
q(t) = qi / (1 + Di * t)
Cumulative Production:
Np(t) = (qi / Di) * ln(1 + Di * t)
Note: EUR is infinite for harmonic decline (requires economic limit)
Decline Rate Conversions
Nominal to Effective:
D_eff = 1 - e^(-D_nom) [for exponential]
D_eff = 1 - (1 + b*D_nom)^(-1/b) [for hyperbolic]
Annual to Monthly:
D_monthly = D_annual / 12 [nominal]