Decline Curves
Decline Curves
I collected these equations from my reservoir engineering course while I was pursuing my postgraduate diploma in Reservoir Engineering at the Universidad de Buenos Aires in Argentina. I just replicated the equations of one of the assignments to code.
Here are the equations for the different types of decline curves.
Exponential Decline
Exponential Decline factor
Where:
- λ = the annual decline rate
- d = the decline rate in percentage, and 12 represents the months in a year
Exponential Monthly decline rate
Exponential Production Rate
Where:
- Q(t) is the production rate at time 𝑡
- Q0 is the initial production rate
- 𝑑 is the decline rate (as a percentage)
- 𝑡 is the time in years
Exponential Cumulative Production Change
Harmonic Decline
Harmonic Production Rate
Where:
- q = current production rate
- Q(t) = the production rate at time t
- Qo = the initial production rate (qoi)
- b = the decline rate parameter
- t = time in years
Harmonic Cumulative Production
Where:
- Np(t) = the cumulative production at time t
- Q0 = the initial production rate
- b = the decline parameter
- Q(t) = the production rate at time t
- The multiplication by 365 converts the result into yearly production, assuming 365 days per year
Harmonic Cumulative Production Change
Hyperbolic Decline
Hyperbolic Production Rate
Where:
- Q(t) = the production rate at time t
- Q0 = the initial production rate
- n = the hyperbolic exponent
- b = the monthly decline rate
- t = the time in years
Hyperbolic Cumulative Production
Where:
- Np(t) = the cumulative production at time t
- Q0 = the initial production rate
- n = the hyperbolic exponent
- b = the monthly decline rate
- Q(t) = the production rate at time t
- The multiplication by 365 converts the result to yearly production assuming 365 days per year
Hyperbolic Cumulative Production Change
For more info about decline curves, check PetroWiki
| Year # | qo (BOPD) | Np (BOPD) | ΔNp (BOPD) |
|---|
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