# exponential: Arps exponential declines In aRpsDCA: Arps Decline Curve Analysis in R

## Description

Compute rates and cumulative production values for Arps exponential decline curves.

## Usage

 ```1 2``` ```exponential.q(qi, D, t) exponential.Np(qi, D, t) ```

## Arguments

 `qi` initial rate [volume / time], i.e. q(t = 0). `D` nominal Arps decline exponent [1 / time]. `t` time at which to evaluate rate or cumulative [time].

## Details

Assumes consistent units of time between `qi`, `D`, and `t`. To convert, see the decline-rate conversion functions referenced below.

## Value

`exponential.q` returns the rate for each element of `t`, in the same units as `qi`.

`exponential.Np` returns the cumulative production for each element of `t`, in the same units as `qi * t`.

`as.effective`, `as.nominal`, `rescale.by.time`.

## Examples

 ```1 2 3 4 5``` ```## qi = 1000 Mscf/d, Di = 95% effective / year, t from 0 to 25 days exponential.q(1000, as.nominal(0.95, from.period="year", to.period="day"), seq(0, 25)) ## qi = 500 bopd, Di = 3.91 nominal / year, t = 5 years exponential.Np(rescale.by.time(500, from.period="day", to.period="year"), 3.91, 5) ```

### Example output

``` [1] 1000.0000  991.8317  983.7301  975.6946  967.7249  959.8202  951.9800
[8]  944.2040  936.4914  928.8418  921.2547  913.7296  906.2660  898.8633
[15]  891.5211  884.2389  877.0161  869.8524  862.7471  855.6999  848.7103
[22]  841.7778  834.9019  828.0821  821.3181  814.6093
[1] 46707.16
```

aRpsDCA documentation built on July 24, 2017, 1:03 a.m.