Standards › Production

Arps decline

Production forecasting and decline (Arps)

Ask Deckhand to forecast a well's decline and estimate ultimate recovery using the Arps decline-curve models.

Decline curve & EUR calculator

What you can ask it to do

  • Fit a well's history to an Arps model — exponential, hyperbolic or harmonic.
  • Forecast future rate and estimate ultimate recovery (EUR).
  • Report the decline parameters and the forecast assumptions.

Why it matters

Reservoir, production and asset engineers forecast estimated ultimate recovery (EUR) and remaining reserves one well at a time from rate history. Doing it consistently across a whole field — picking the decline exponent b, fitting the same way every time, and reconciling the forecast to an economic cut-off — is repetitive and easy to do subjectively. A standards-traceable Arps fit gives every well the same defensible treatment with the parameters and assumptions written down.

The method — governing equations

Arps decline-curve analysis fits the rate history to one of three empirical models and integrates to recovery at the economic rate:

Rate–time (general / hyperbolic, 0 < b < 1):
  q(t) = qi / (1 + b · Di · t)1/b
  Exponential (b = 0):  q(t) = qi · e−Dit
  Harmonic (b = 1):  q(t) = qi / (1 + Di · t)
Cumulative to an economic rate qab:
  Exponential:  Np = (qi − qab) / Di
  Hyperbolic:  Np = qib / ((1−b)Di) · (qi1−b − qab1−b)
  Harmonic:  Np = (qi / Di) · ln(qi / qab)

where qi is the initial rate, Di the initial nominal decline rate, b the decline exponent and qab the economic abandonment rate. The parameters qi, Di and b are fitted by regression to the history; EUR is the cumulative produced to date plus Np from the current rate to qab.

These are the standard Arps relationships. No numeric example is shown here on purpose — the calculator and Deckhand fit the parameters and compute the forecast and EUR deterministically from your rate history, so every figure is reproducible and traceable.

What a screening check covers — and what it does not

Covers

  • Single-well, single-phase boundary-dominated (depletion) decline fits.
  • Exponential, hyperbolic and harmonic models with fitted qi, Di, b.
  • Forward rate forecast and EUR to a user-supplied economic rate.
  • A parameter report with the fit assumptions stated.

Does not cover

  • Transient / early-time flow before boundary-dominated decline, where Arps over-forecasts.
  • Modified-Arps terminal decline or multi-segment fits unless specified.
  • Rate-transient, material-balance or numerical-simulation methods.
  • Well interference, workovers, choke changes, commingled allocation, or economics and pricing.

The screening assumes the history reflects established decline under roughly constant operating conditions; wells in transient flow or with operational changes need a method-of-record review.

Related standards

Arps decline EUR Exponential / hyperbolic / harmonic Decline curve Production forecast

Part of Wells & Subsurface · see the platform engine

Questions

What is Arps decline-curve analysis?

The standard empirical method for forecasting oil and gas production decline — exponential, hyperbolic or harmonic — and estimating ultimate recovery from the rate history.

What does Deckhand return?

The fitted decline parameters, a forward rate forecast, and the estimated ultimate recovery with the assumptions stated.

Run Arps decline on your own inputs

Every capability is free to explore — open the published dataset behind the check and read the numbers yourself.

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