1

abbasis@ripi.ir

(Decline Curve Analysis)

KEYWORD: Decline Curve Analysis, Exponential Decline, Hyperbolic Decline,

Harmonic Decline, History Matching, Decline Rate, Nominal Decline Rate, Cumulative

Production, Flow Rate

(Decline Curve Analysis, DC)

D.C.

DC

2

(Exponential Decline)

(WOR)

(WOR+1)

D.C.

WORWGR

DC

D.C

DC

DCTubingChoke Setting

Workovers

Artificial liftAcidizing

Work overWork over

Work over

DC

DC

1 BCF

Well head0.7BCF0.9

BCF

3

Exponential,HyperbolicHarmonic

DC

D

D

D

(Hyperbolic)

Time

F

low

Rat

e

Slope

D=Slope/ Rate

Flo

w R

ate

Time

Harmonic

Exponential

Hyperbolic

4

Arps

HyperbolicExponentiacl

Arps

Arps

Arps(b)(Di)

Arps

HyperbolicExponentialSemi-logArp

Harmonic

Arps

(Hyperbolic)

SliderHyperbolic(Curve-

Maching)Semi-log

SliderCurve-Fitting

Arps

Gently

ArpsGently

Arps

FetkovichArps

5

Fetkovich

Arps

GentlyFetkovich

Gently

Carter

(µCg)

Cg

FraimWattenbarger

Cg

Aminian

SchmidtCaudle

MillerAminian

(Non-Darcy)Schmidt

(Turbulent)

Schmidt

(Exponential Decline)

(D)(Exponential)

D

D

D.C

6

D

Exponential

HyperbolicHarmonic

Decline CurveD

t1t2

Exponentialq2t2q1t1

q2

Cumulative Production

Flo

w R

ate

Slope

D= Slope=Const.

D

Time

LO

G. F

low

R

ate

Slope

Rate

D=Slope×2.302

7

Ddd

dD

D d

DdD

d

dD

(Exponential)(Nominal)

DD

(DRt)D

(DRc)

(qEc)

Workover

Time

Flo

w R

ate

Slope

Rate

D=Slope/ Rate

Time

Rate

d=Slope/ Rate

Flo

w R

ate

8

Workover

Workover

Skin

AB

Hyperbolic

Hyperbolic

0<b<1hyperbolic(D)

Diqi

Dbb

b=0b=1harmonic

Cumulative Production

A B

Workover

Economic Limit

Flo

w R

ate

M

Economic Limit

Cumulative Production

Workover

B A M2 M1

Flo

w R

ate

Workover

Workover

9

hyperbolicqiDi

t=0bDiqi

t

hyperbolic

Robertson

hyperbolicExponential

hyperbolic

(Harmonic)

(harmonic)hyperbolicb=1D

qqD

(Gravity Drainage)

Water Cut

harmonic

Time

Log

. Flo

w R

ate

Slope

Rate

D=Not Constant

Time

L

og. F

low

Rat

e

Exponential Decline

Hyperbolic Decline

hyperbolic

Exponential

Hyperbolic

10

D

harmonicD

kqi

Diharmonic

hyperbolicb=1

t1t2q1q2

harmonic

GORWORWGR

Diqi

GORo

g

qq

WORo

wq

q

11

GORWOR

GORWOR

CGR

(CGR)

CGR

(lifting)WOR

LGRlifting

LGR

(Operated-Day Rate)

(Calendar-day Rate)

Operated-day Rate

Down time

Down timeLoud factor

Loud factor(LF)LF

Calendar-day RateOperated-day Rata

ExponentialHyperbolicHarmonic

12

hyperbolic

hyperbolic

Exponential

(Gravity Drainage)

harmonic

GORWORGIR

WGR

Pool

References 1. Manual for the oil and gas industry (Revised August, 1921). Government

printing office, Washington, DC(1921).

2. Arps, J .J .: Ana lysis of decline curves, Trans. AIME (1945) 160,228-247.

3. Slider , H.C.: A simplified method of hyperbolic decline curve ana lysis,

JPT (March 1968) 235-236.

4. Gentry, R.W.: decline curve ana lysis. J PT (J an .1972) 38-41.

13

5. Fetkovich, M.J .: Decline curve analysis usin type curves JPT (June 1980)

1065-1077.

6. Car ter R.D.: Type curves for fin it e radial and linear gas flow systems:

Constan t t ermina l pressure case, SPEJ (Oct . 1985) 719-728.

7. Fra im, M.L. and Wat tenbarger , R.A.: Gas reservoir decline curve ana lysis

using type curves with rea l gas pseudo pressure and normalized t ime,

APEFE (Dec. 1987) 671-682; Trans. AIME,290.

8. Amin ian , K., Amer i, S., and Hyman, M.: Product ion decline type curves

for gas well producing under pseudo-steady sta te condit ions, paper SPE

15933 presented at the 1986 SPE eastern regional meeting, Columbus,

OH, Nov. 12-14.

9. Schmidt , S.H., Caudle, B.H., and Miller , M.A.: Gas well decline ana lysis

incorporating real gas behavior and Non-Darcy flow, paper SPE 15521

presented at the 1986 SPE annual technical conference and exhibition,

New Orleans, LA, Oct. 5-8

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