Primary funding is provided by

The SPE Foundation through member donations and a contribution from Offshore Europe

The Society is grateful to those companies that allow their professionals to serve as lecturers

Additional support provided by AIME

Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl 1

Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl

2

Development of Mature Oil Fields: Enhanced Oil Recovery Option

Tayfun BabadagliProfessor and NSERC-IRC in Unconventional Oil Recovery

University of Alberta

3

•What is a mature field?

•How much oil is left and where it is

•Recovery of remaining oil: Tertiary recovery

•Laboratory scale

•Field scale

•Key points and suggestions

OUTLINE

4

What is a Mature Field?

qbbl/day

Time, years

? ?

?

?

?

• Rate: Producing but declining • Recovery Factor: 50% - 60 years (99% water cut)• Recovery Factor: 10% - 60 years (0% water cut)

5

Giant Field Discoveries

OIL FIELDS IN THE WORLD: 30,000

020406080

100120140160180200

1868

-99

1900

-09

1910

-19

1920

-29

1930

-39

1940

-49

1950

-59

1960

-69

1970

-79

1980

-89

1990

-99

2000

-09

2010

-12

Num

ber o

f Fie

lds

Time, years

Oil giants Gas giants

TOTAL RESERVES: 150 MMMm333 Fields: 50%

OIL FIELDS IN THE WORLD: 30,000

OGJ, Feb. 3, 2014

6

OIL FIELDS IN THE WORLD: 30,000

50-70% left behind!!!

Additional reserves are from new discoveries or existing fields?

020406080

100120140160180200

1868

-99

1900

-09

1910

-19

1920

-29

1930

-39

1940

-49

1950

-59

1960

-69

1970

-79

1980

-89

1990

-99

2000

-09

2010

-12

Num

ber o

f Fie

lds

Time, years

Oil giants Gas giants

Giant Field Discoveries

OGJ, Feb. 3, 2014

7

Stages In Mature Field Development

WELL ENHANCEMENTo Optimization of lifto Well stimulationo Re-visiting wells

DRILLINGo Verticals / Horizontalso Multilaterals / Side-trackingo Infills

SECONDARY RECOVERYo Pressure maintenanceo Waterfloodingo Gas (immiscible) injection

TERTIARY RECOVERY o Gas (CO2, hydrocarbon-rich)o Chemical (surfactant, micellar)o Thermal (air)

BROAD SUBJECT

Well Reservoir

8

AdvantagesData and experience gained

HistoryModern technologies

Development of Mature Fields

DisadvantagesCost

EfficiencyTime to start the project

•Incremental OIL (How much)•Recovery TIME (How fast)

•COST (How expensive)•Company Size

•Long/Short Term

9

What is Mature Field?

qbbl/day

Time, years

TERTIARY vs. SECONDARYRecovery is lower - Investment is higher

Company’s cut-off limit for cost: $10, $30, $50/bbl?Your target is residual oil reduction rather than rate?

10

Elements of Mature Field Development (Tertiary Recovery)

How much oil is left and where it is

Tertiary recoveryLaboratory

Field

11

Determination of Remaining Oil Saturation

•Core Analysis•Logs•Reservoir Engineering Studies•Production Data•Chemical Tracers•Well Testing (with core analysis)

log(t)

P

Pkhqtq DD

2)(

tdit

ieqq

oigspop NBBRRBN ])([

12

Remaining Oil Saturations – Different Methods(33 sandstone fields)

0

5

10

15

20

25

30

35

40

45

50

Res

idua

l Oil,

%

Sample 32

Material Balance

Resistivity Logs

PulsedNeutronCapture

Log-Inject-Log

Water-OilRatio Relative

Permeabilities

Determination of Residual Oil Saturation, Bond, Hocott, Poettmann (Eds.), Interstate Oil Compact Comm., 1978

13

-Remaining Oil -No Distribution

Field

RESIDUAL OIL SOLUTION

Material Balance(% PV)

Tracer Test(%PV)

1 16 12 No tertiary oil recovery More wells between producers

2 40 29 Tertiary oil recovery

3 44 12 Oil in isolated pockets Infill

Determination of Residual Oil Saturation, Bond, Hocott, Poettmann (Eds.), Interstate Oil Compact Comm., 1978

-Remaining Oil -Distribution

Remaining Oil Saturations – Different Methods

14

Oil: From 34 to 253 bbl/d

Water: Completely stopped

Cased Hole Formation Resistivity Logs-Nuclear logs (Neutron,C/O) : Not reliable

-New tool for resistivitythrough metal casing

Cement squeeze

Re-perforate

28 ft

OWC 2012

OWC 1978

1 10 100 1000

RT CHFR2002

RLLD1978

(Petrophysics, 2004 no.4)

Remaining Oil

Remaining Oil

15

Remaining Oil Saturation: Yates Field

•Discovered in 1927•1.3 billion barrel produced

•Strongly heterogeneous mixed wet carbonate•1100 producers - 57 injectors (1992)

SOLUTION : NMRAlternative to resistivity saturation.

Insensitive to gas

Oil/water by diffusion coefficient

SPE 63216

PROBLEMS

Borehole filled with gas, no electromagnetic propagation

n and m between 1 and 5

(in space - time)

16

Comparison: Remaining Oil Saturation (ROS)

ROS (Core, log, tracer) < ROS (Material balance)

ROS (Pulsed Neutron Capture) = ROS (Resistivity)

ROS (Single well tracer) < ROS (Logs)

17

Tertiary Recovery – Field Applications

•Immiscible gas injection-Double displacement-Inert gas

•Miscible gas injection-HC gases-CO2

•Chemical (surfactant) injection

18

Tertiary Gas Injection Applications

19

Tertiary Chemical Injection Applications

20

Surfactant Flood: Incremental Recovery

0102030405060708090

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Oil

Satu

ratio

n, %

Residual Oil After Waterflooding

Final Oil Saturation After Surfactant Flood

CORE FLOOD RESULTS

Loudon Field: 13 years primary, 38 years waterflooding.

Remaining oil: 50 % OOIP

SPE 20218

5-30%

21JCPT

Jan-Feb 1990

P1T1

T2P2

Micellar Flood (Composition)

Type Oil (%) Brine (%) Surfactant (%) Co-Surfactant (%)

P1 64 20 12 4 (Isopropyl Alcohol)

T1 85 5 8.5 1.5 (Isopropyl Alcohol)

P2 6 84 7.5 3 (Cyclohexanol)

T2 2 93 4 1.5 (Cyclohexanol)

22

Sequence of Methods

46th Annual Tech. Meet. of the Petroleum Society, Banff, Canada, 1995, Paper 65-95

0102030405060708090

100

Tertiary WAG Secondary Slug

InitialOil

Residual Oil(Waterflooding)

Residual Oil(Gas Injection)

Residual Oil(Blow Down)

Flue gas injection as water-alternating-gas (WAG)

14 oAPI Oil

Residual Oil(Extended

Waterflooding)

Oil

Satu

ratio

n, %

OO

IP

23

Miscibility after waterflood

• Solvent invade only waterfilled pores.

• Oil may not be displacedfrom the smaller pores.

• Water film between solventand oil/grain

Tertiary Recovery by Hydrocarbon Solvent

Heptane

Grain Water Oil

200 microns

24

Tertiary Recovery by Solvent

Solvent Water Water Solvent Water

Kerosene (2 cp)

RF=69% RF=47%

25

Tertiary Recovery by Solvent

Solvent Water

Kerosene (2 cp) - Mixed Wet

Water Solvent Water

RF=85% RFfinal =64%RFwater =73%

RF=69% RFfinal =47%RFwater =66%Water wet

Mixed wet

26SPE 77641

RF=30%

YIBAL FIELD

RF=40%

• Big field: 450 wells• Long term targets• High investment

• Chalky carbonate• Light oil (1cP)• Natural water influx

27

05

101520253035404550556065707580859095

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27Experiments in ascending order

Water Injection Surfactant Injection After WaterfloodingContinued With Another Surfactant Surfactant Injection

Oil

Rec

over

y, %

OO

IP

WATER INJECTION ONLY = 75% SURFACTANT ONLY = 70%

Yibal Field (Chalk) Dilute Surfactant Performance

28

SAHMAH FIELD

0

800

1600

2400

3200

0 2000 4000 6000 8000

Oil

Rat

e, m

3 /day

Time, days

2002

• Sandstone • Oil: 45 oAPI, 1 cP• Natural water influx• Deep: 3,250m

-Small field: 20 wells

-Small company

-Short term targets

-Low investment

• Two sandstone layers: • Low permeability (1 mD), RF=10%• High permeability (150 mD), RF=70%

29

Oil

Rec

over

y, d

ecim

al (O

OIP

)Injection Pressure, psi

Nitrogen injection into tight zone

30

Oil

Rec

over

y, d

ecim

al (O

OIP

)Injection Pressure, psi

Water Injection (q=1 cc/min)

Nitrogen injection started

Nitrogen injection into waterflooded zone

31

Field scale simulation

0100200300400500600700800900

1000

0 2000 4000 6000 8000 10000 12000

Time (days)

Base case

8250 psi

6750 psi

5250 psi

3750 psi

Oil

Prod

uctio

n, m

3 / d

ay

One converted injector

32

Concluding Remarks•Locate the remaining oil

•Proper tertiary recovery method

•Small companies faster recovery (short term)

•Big companies higher ultimate recovery (long term)

•Laboratory experiments

•When to start tertiary recovery

•Role of water (or gas) saturation history

•Interaction with injectant to reduce residual oil saturation

•Injection design (sequence, WAG ratios, slug sizes)

33

•Be proactive: Forecast the impacts a few decades ahead

•Reservoir characterization for optimal design

•Human factor: Experience and expertise

Further Suggestions

34

No luxury of leaving ~50% of oil trapped in matureand marginal fields.

Bottom Line

The careful selection anddesign of technically andeconomically viable technique.

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