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Waterflood Surveillance-1

Dosen : Ir Andry halim, MM

STT MIGAS, Bali!a!an

"##$

%ecture 1#

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&oida'e (ontrol

"

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Desi'n of Waterflood )ro*ect

&oida'e (ontrol

+ &oida'e control involves monitorin' in*ection and ithdraal

volumes to ensure the correct in*ection is added to the

reservoir and at the !ro!er locations to maimi.e secondary

recovery

+ Where: Bo / 0il formation volume factor 2B3SlB4

5! / 0il !roduction at stoc tan conditions

W! / Water !roduction

6

2eservoir Withdraal s / W! 7 5!Bo

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Desi'n of Waterflood

&oida'e (ontrol

)ro*ect

+ If free 'as eists 8 is 9ein' !roduced:

Where: B'/ Gas formation volume factor

2(3S(4

Surface !roduced4 'as oil ratioS(3SlB04

Solution 'as oil ratio S(3SlB04

2! /

2s/

;

2eservoir Withdraal s / W! 7 5!Bo 75!2! - 2s4B'

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&oida'e (ontrol

+ In*ection Withdraal 2atio IW24 - commonly used

for monitorin' aterfloods

+ Monthly secondary recovery re!orts should alayscontain calculated IW2 for each !attern

+ (alculated 9y dividin' effective in*ection 9yreservoir ithdraals:

2eservoir Withdraals

uals ithdraals, IW2 / 1?#

+ IW2 ill vary durin' the aterflood life

- Durin' re!ressurin' early in the life of aterflood, IW2

ill 9e hi'h 9ecause reservoir !ressure islo 8 ithdraals have not started increasin'

- After fill-u! is reached 8 aterflood is a!!roachin'steady-state, IW2 ill decrease 8 a!!roach 1?#

- If IW2 dro!s to 9elo 1?#, total fluid volume ill 9e'into decrease 8 corrective actions should 9e taen

$

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&oida'e Data Sources

+ " useful !lots are avera'e reservoir !ressure

versus time and avera'e reservoir !ressure versuscumulative oil

+ 5ote the !ressure chan'e in the late 1@#s after a fore destroyed

in*ection facilities

field

+ lhe effect on reservoir re!ressurin' as si'nificant, 9ut ould have 9een

difficult to monitor ithout this avera'e reservoir !ressure curve

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)attern &oida'e

+ )attern allocation usually

uses a !attern allocation

factor calculated usin'

an'le 9eteen in*ection

ell 8 to ad*acent offset

in*ection ells in

the !attern

or interior !atterns, divide

this an'le 9y 6$#o to o9tain

factoractors are sometimes

ad*usted ei'hted4 for

reservoir !ay volumes

+

+

C

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&oida'e (alculation

=am!le )ro9lem 1?$-1

A small aterflood is !roducin' 1$,

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)attern &oida'e (alculation

=am!le )ro9lem 1?$-"

A mature

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&oida'e (alculation

=am!le

A small

BW)D?

)ro9lem

aterflood

The ater

1?$-1

is !roducin' 1$,

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)attern &oida'e (alculation

=am!le )ro9lem 1?$-"

A mature

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&oida'e Ma!!in'

)attern &oida'e Ma!

+ lo vie 'ra!hically the !attern voida'e across a field or

reservoir, a colored !attern ma! is sometimes used

+ )atterns are classified as over 9alanced, under

9alanced, or 9alanced 9ased on in*ectionithdraal ratios

16

Ender Balanced

0ver Balanced

Balanced

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&oida'e Ma!!in'

)attern &oida'e Bu99le Ma!+ Eseful !attern voida'e tool

- (reates 9u99les shoin' !ositive 8 ne'ative voida'e 9y !atterns

- )ositive 8 ne'ative voida'es have different colors

- =ither diameter or area of 9u99le are !ro!ortional to

a9solute value of voida'e or IW2

1;

Ender Balanced

0ver Balanced

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Ste! for Esin' &oida'e Ma!+ Set routine schedule for evaluatin' !attern voida'e !erformance

+ Define o!timum data needed 8 most effective 'ra!hical !resentation

+ =sta9lish 9aseline of !attern !erformance:

- What is ty!ical for !atterns in this reservoirF

- What is ty!ical for each !attern throu'h timeF

+ =valuate current !attern voida'e data:

- (lues from 'eneral !attern voida'e trends

- 2elative ma'nitude of voida'e anomalies

+ Identify anomalies

+ Determine if voida'e anomalies are si'nificant

+ Determine conclusions a9out !attern voida'e:

- Is calculated !attern voida'e validF

- as it 9een occurrin' for some timeF

- Is it si'nificantF

- What are !ossi9le root causesF

+ Identify ells hich may 9e contri9utin' to !attern voida'e anomaly

+ Identify o!tions

(h $ -11

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