Re Seng Covers

Ref. No. RE/1, Version 1.0

'Proven'

'Proven + Probable'

Pro

babi

lity

that

the

rese

rve

is a

t lea

stas

larg

e as

indi

cate

d.

'Proven + Proable+ Possible'

1.0

0.9

0.5

0.1

0Recoverable Reserve

47/7 A4

A2

47/8-1

47/8-2

47/2 47/3

47/8

A3

A6

A5x

x

x

Gw

C

GwC

95509500

95009500

9600

9450940093509300

9250

9200

9100

91509350

9300

9250

9200

8

88

Platform A

Completed Producers

Proposed Well Locations

Abandoned Wells

C.I. = 50ft.

88

888

B

88

8 A

AA

A

A

1Introduction To Reservoir Engineering1


22Reservoir Pressures and Temperatures

4000

8100

8200

8300

8400

8500

8600

8700

8800

2500

2550

2600

2650

Layer 4

Layer 1

Layer 2

Layer 3

Layer 5

2500 3000 3500

14 16 18 20 22 24 26

True

ver

tical

sub

sea

dept

h -

met

res

True

ver

tical

sub

sea

dept

h -

feet

Reservoir pressure - MPa

Reservoir pressure - psig

Perforations Originalpressuregradient

Top paleocene

Gr%0 100

Sw%100 0

θ%0 50

4

21

3

5

Note: Water gradient lines drawn through known or projected oil/water contacts

Alwyn

Lyell

NinianOWC

HeatherOWC

CormorantOWC

S.W> Ninian

N.W. Alwyn

Thistle OWC

Brent OWC

Statfjord OWC

5000 6000 7000 8000 9000 10,000

13,000

12,000

11,000

10,000

9,000

8,000

Pressure, psig

Sub

sea

Dep

th (

Fee

t)


33Reservoir Fluids Composition

Reservoir Fluid Gas at Surface Conditions

Oil at Surface Conditions

C1 C2 C3 C4 C5 C6 C7+

The relative amounts of C1 - C7+ are afunction of :

Temperature, Pressure, Composition (particularly at high temperature)


Bubble

Poin

t Lin

e

Dew Point Line

% Liq.

100

75

50

25

510

0

Pre

ssur

e

Temperature

Liquid

Gas

1

2

3

Cricondenbar

Cric

onde

nthe

rm

Region of retrograde condensation

44Phase Behaviour of Hydrocarbon Systems

0

1000

2000

3000

4000

5000

6000

0 -100 0 100 200 300 400 500 600 700

Temperature º F

Pre

ssur

e Lb

s. (

psia

)

M

etha

ne

Ethane

PropaneN-Butane

N- Pentane

N-HexaneN-Heptane

N-Decane

Two Phases

Single Phase


55Behaviour of Gases

Vsat (liq) Vsat (vap)

V

P

Psat

c

T1>Tc

Tc

T2<Tc

.008

.006

.004

.002

1000 2000 3000

Bgrb/scf

PRESSURE (psig)


6Properties of Reservoir Liquids6

567SCF/STB

AT 1200 PSIARS = 337

BU

BB

LE P

OIN

T P

RE

SS

UR

E

INIT

IAL

PR

ES

SU

RE

Sol

utio

n G

as, S

CF

/ST

B

600

500

400

300

200

100

00 500 1000 1500 2000

Pressure, PSIA

2500 3000 3500

70

60

50

40

30

10

20

30

40

50

60

70D

ensi

ty o

f sys

tem

incl

udin

g m

etha

ne a

nd e

than

e, lb

/cu

ft

Den

sity

of p

ropa

ne p

lus,

lb/c

u ft

Wt %

etha

nein

etha

nepl

usm

ater

ial

01020304050

Wt %

met

hane

inen

tire

syste

m

0

10

20

30


77Fundamental Properties of Reservoir Rocks

100

80

0 5

Reciprocal Mean Pressure: (Atm.)

Ga

s P

erm

ea

bili

ty:

Mill

ida

rcie

s

60

40

20

01 2 3 4

Hydrogen

Nitrogen

Carbon Dioxide

Liquid permeability

Whole core

Core plugfor horizontal k measurement

4 Inch

Formation

Core plugfor vertical k measurement


88Rock Properties Measurement

0 0.1

2

0

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Normalised Wetting Phase Saturation Sw* ( (Sw-Swc1-Swc

=

Dim

ensi

onle

ss C

apill

ary

Pre

ssur

eP

cK

σφ

LEGEND

Different reservoir sand sequence in a formation

Platen

Threadedend cap

Trapped tube

CoreRubbersleeve Aluminium

cell body

Maximum principal stress

σ2

σ2 σ3

σ3

1

23

332

2 2

2

2

2

2

11

1

3

3

3

3

3

3

33 3

AA

Section AA

Hydraulicallypressured tubes

Face ofcore plus


99Permeability - Its Variations

Reservoir

InjectionPump

Separation

Limited flaringRe-inject

qwi

Seawaterfor injection

Sea Level

Sea Bed

qo + qwpqwp

Purify /Dump /inject

Gas

qo sales

Normal log scale

Permeability (mD)

Log (Permeability mD)10 20 30 40

20

40

60

80

20

40

60

80

1000 2000 3000 4000 5000

Linear scale

Thickness (ft)

Thickness (ft)

Permeability Distributions


1010Fluid Flow In Porous Media

1 2 3 4 5 6 7 8 9 10

Outlet

(constant flowrate)

Initialwaterprofile

Profileaftertime t

Tube number

Interconnecting, small diameter pipes

10 vertical tubes, 100mm diameter, arranged linearly

time, t after start of flow

top of tubes 0

-50

-100

-150

-200

-2501 2 3 4 5 6 7 8 9 10

tube number

bottom of tubes

heig

ht o

f wat

er in

tube

s

t=0t=1t=2t=3t=4t=5t=6t=7


1111Drive Mechanisms

Time-Year

ReservoirPressure

ReservoirPressure

OilProd

OilProd

G.O.R

G.O.R

Gas cap

Gas cap expansionSolution gas liberation

With production -

Oil may be above Pb

Gas cap present initiallyOil at interface is at Pb

Oil


1212Vapour Liquid Equlibria

CUSTOMERS

ONSHORE FACILITIES

OFFSHORE FACILITIESOFFSHORE FACILITIES

RESERVOIRRESERVOIR

WELLS WELLS

T & PF

zj

V

yj

L

xj


1313Equilibrium Ratio Prediction and Calculation

500400300250200

10080

604020

0-20-40

-60

Temperature °F

10 30 50 100 300 500 1,000 3,000 10,0002 4 6 7 8 9 2 4 6 7 8 9 2 4 6 7 8 9

10 30 50 100 300 500 1,000 3,000 10,0002 4 6 7 8 9 2 4 6 7 8 9 2 4 6 7 8 9 1,0009876

5

4

3

2

1009876

5

4

3

2

109876

5

4

3

2

1.09876

5

4

3

2

0.19876

5

4

3

2

1,0009876

5

4

3

2

1009876

5

4

3

2

109876

5

4

3

2

1.09876

5

4

3

2

0.19876

5

4

3

2

Pressure, PSIA

Pressure, PSIA

K= y/x K= y/x

ETHANECONV. PRESS. 5000 PSIA

Plotted from 1947 tabulationof G. G. Brown, University of Michigan. Extrapolated and drawn by The Fluor Corp. Ltd.in 1957.

Component 1

CONSTANT TEMPERATURE

Component 2

In Pc

In P

In Kj

Kj - 1.0


1414PVT Analysis

P = Pb P1 < Pb P = P1 P < P1

GasOil

GasOilMercury / displacing fluid

Gas Oil

At each stage - volume of oil and gas, density andcomposition of gas measured.Remaining oil is called RESIDUAL OIL

Valve 1

PVT Cell

closed

Pump

P

Tres

P

Pb

VbV

V


1515Material Balance Equation

Prim. Gas cap

Oil + originallydissolved gas

Connate water

Initial volumesat pressure Pi

New pore volumeat pressure p

FLUID VOLUMES

PORE VOLUMES

Total pore volumeat pressure Pi

Reduction in totalpore volume down topressure P

Fluid expansionsdown to pressure P

Water influx We


1616Material Balance Equation Application

Strong water drive

Moderate water drive

Volumetric depletion

G = initial gas in place

F/Eg

Gp

Cumulative Production, MMMSCF

5000

4000

3000

2000

1000

0

Pre

ssur

e or

P/Z

1 2 3 4 5 6 7

Water drive

VolumetricGp vs p/z

VolumetricGp vs p

Wrongextrapolation

Initi

al g

as in

pla

ce


1717Water Influx

∆P1 = 1/2 (Pi - P1)

∆P2 = 1/2 (Pi - P2)

∆P3 = 1/2 (P1 - P3)

∆P4 = 1/2 (P2 - P4)

∆P2∆P1

∆P3

∆P4

∆P5

PiP1

P2

P3

P4

0 1 2 3 4 5

TIME PERIODS

AV

ER

AG

E B

OU

ND

AR

Y P

RE

SS

UR

ES

θ

Reservoir

Aquifer

OWC


1818Immiscible Displacement

WaterOil

Core Plug

Saturations:Water 1- SorOil Sor

Mobility:Krw'/µwO

Saturations:Water SwiOil 1- Swi

Mobility:OKro'/µo


Examination and Model Solutions

• graph made of P vs V and intersection of two slopes indicates

bubble point pressure

• used to determine Pb and Bo above bubble point and BT over total

pressure

P

Gas

Oil

Hg

VVb

Pb

P

b) Separator Test

• oil from PVT cell at reservoir temperature and at bubble point

pressure released to surface conditions

• gas collected from each stage collected and final volume of oil at

standard conditions measured

• volume of oil removed from PVT cell at bubble point and

reservoir temperature measured

• used to determine GOR and Bob as a function of separator

conditions

��

yyyyyyyyyyyyyyyy

Date:

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Subject:

INSTRUCTIONS TO CANDIDATES

8 Pages

PLEASE READ EXAMINATION REGULATIONS ON BACK COVER

No. Mk.

NAM

E:REGISTRATION N

O.:

COURSE:

YEAR:

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