# hyp2exp: Arps hyperbolic-to-exponential declines In aRpsDCA: Arps Decline Curve Analysis in R

## Description

Compute rates, cumulative production values, instantaneous nominal declines, and transition times for Arps hyperbolic-to-exponential decline curves.

## Usage

 ```1 2 3 4``` ```hyp2exp.q(qi, Di, b, Df, t) hyp2exp.Np(qi, Di, b, Df, t) hyp2exp.D(Di, b, Df, t) hyp2exp.transition(Di, b, Df) ```

## Arguments

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

## Details

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

When appropriate, internally uses `harmonic.q` and `harmonic.Np` to avoid singularities in calculations for `b` near 1.

## Value

`hyp2exp.q` returns the rate for each element of `t`, in the same units as `qi`.

`hyp2exp.Np` returns the cumulative production for each element of `t`, in the same units as `qi * t`.

`hyp2exp.D` returns the nominal instantaneous decline for each element of `t`. This can be converted to effective decline and rescaled in time by use of `as.effective` and `rescale.by.time`.

`hyp2exp.transition` returns the transition time (from hyperbolic to exponential decline), in the same units as `1 / Di`.

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

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16``` ```## qi = 1000 Mscf/d, Di = 95% effective / year, b = 1.2, ## Df = 15% effective / year, t from 0 to 25 years ## result in Mscf/d hyp2exp.q(1000, as.nominal(0.95), 1.2, as.nominal(0.15), seq(0, 25)) ## qi = 500 bopd, Di = 3.91 nominal / year, b = 0.5, ## Df = 0.3 nominal / year, t = 20 years hyp2exp.Np(rescale.by.time(500, from.period="day", to.period="year"), 3.91, 0.5, 0.3, 20) ## Di = 85% effective / year, b = 1.5, Df = 15% effective / year, ## t = 6 and 48 months hyp2exp.D(as.nominal(0.85), 1.5, as.nominal(0.15), c(0.5, 4)) ## Di = 85% effective / year, b = 1.5, Df = 5% effective / year hyp2exp.transition(as.nominal(0.85), 1.5, as.nominal(0.05)) ```

### Example output

``` [1] 1000.000000  280.611170  173.356767  128.007825  102.537125   86.041315
[7]   73.135118   62.164850   52.840123   44.914104   38.176989   32.450440
[13]   27.582874   23.445443   19.928627   16.939333   14.398433   12.238668
[19]   10.402868    8.842438    7.516072    6.388661    5.430362    4.615808
[25]    3.923437    3.334921
[1] 89774.35
[1] 0.7830150 0.1625189
[1] 12.64574
```

aRpsDCA documentation built on May 2, 2019, 9:42 a.m.