curtailed: Arps decline curves with initial curtailment

In aRpsDCA: Arps Decline Curve Analysis in R

Description

Create decline curve objects and compute rates, cumulative production, and nominal declines for Arps decline curves with an initial period of curtailment to constant rate. The resulting decline curve models will impose a constant rate of production equal to the initial rate of the underlying model until the specified end-of-curtailment time.

Usage

    curtail(decl, t.curtail)
    curtailed.q(decl, t.curtail, t)
    curtailed.Np(decl, t.curtail, t)
    curtailed.D(decl, t.curtail, t)

Arguments

decl	an Arps decline object as returned by arps.decline.
t.curtail	time to end of curtailment, in same units as t [time].
t	time at which to evaluate rate, cumulative, or nominal decline [time].

Details

Assumes consistent units as described for underlying Arps decline types.

Value

curtail returns an object having class "arps", suitable for use as an argument to S3 methods listed in arps.

curtailed.q returns the rate for each element of t, under a decline described by decl and curtailed until time t.curtail.

curtailed.Np returns the cumulative production for each element of t, under a decline described by decl and curtailed until time t.curtail.

curtailed.D returns the nominal instantaneous decline for each element of t, under a decline described by decl and curtailed until time t.curtail.

See Also

arps, print.arps, exponential, hyperbolic, hyp2exp.

Examples

## qi = 1000 Mscf/d, Di = 95% effective / year, b = 1.2, t from 0 to 25 days,
## curtailed until 5 days
curtailed.q(arps.decline(
        1000,
        as.nominal(0.95, from.period="year", to.period="day"),
        1.2
    ),
    5, seq(0, 25))

## hyperbolic decline with
## qi = 500 bopd, Di = 3.91 nominal / year, b = 1.5,
## curtailed for 1 month
## cumulative production at t = 5 years
decline <- curtail(
    arps.decline(rescale.by.time(500, from="day", to="year"),
                 3.91, 1.5),
    (1 / 12)
)
arps.Np(decline, 5)

Example output

 [1] 1000.0000 1000.0000 1000.0000 1000.0000 1000.0000 1000.0000  991.8714
 [8]  983.8869  976.0423  968.3341  960.7585  953.3121  945.9915  938.7934
[15]  931.7148  924.7525  917.9037  911.1654  904.5351  898.0099  891.5875
[22]  885.2652  879.0407  872.9117  866.8759  860.9312
[1] 211535.4

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