Search for reserves utilizing subsea multilateral and smart well technology

Search for reserves utilizing subsea multilateral and smart well technologyVibeke HaugenGF SAT

2

Outline• Background

• IOR project – solutions chosen

• Why MLT and DIACS

• Assessment of smart well technology for GFS Statfjord

• Production experience

• Experience with swell packers

• Conclusion

3

Gullfaks Satellitter • Utbyggingen av Gullfaks Satellitter

er gjennomført i to faser• Bygget ut som undervanns

produksjonssystem knyttet opp mot eksisterende infrastruktur

• Utbyggingen består av feltene Gullveig, Rimfaks og Gullfaks Sør som ligger 10-17 km sør/sørvest for Gullfaks plattformene

4

Gullfaks Satellitter•Fase 1

– Oljeutvinning fra feltene Gullveig, Rimfaks og Gullfaks Sør– Olje/gass produseres til Gullfaks A– Gass reinjiseres på Gullfaks Sør og Rimfaks– Produksjonsstart 10.oktober 1998

•Fase 2– Gassutvinning fra Gullfaks Sør med tilhørende kondensat– Gass/kondensat produseres til Gullfaks C– Produksjonsstart september 2001

5

Fase 1 utbyggingen• Består av 8 brønnrammer (D, E, F,

G, H, I, J og K) • Totalt 31 slisser, hvorav 9 er

beregnet på gassinjeksjon og 22 på oljeproduksjon

• Gjenstår 1 slisse på G-rammen, 1 på F-rammen og 2 på E-rammen

6

Gullfaks Sør – Statfjord formation

Tampen area

Discovered in 1979, and part of the Gullfaks Satellites – tie in to Gullfaks field – 10 km

Statfjord formation consist of 134 m oil zone, and gas cap

Statfjord formation

Production start: April 1999

Reservoir depth: 3300 m

Pressure, initial: 476 bar

Temp. @ 3300 m: 128 oC

Daily avg. production-05 (Sm3/d) 1300

Available slots 7/2

Wells drilled 2004 3

Wells producing 5

7

Gullfaks Sør Statfjord FormationPDO 1995: Large volumes in the Statfjord fm.

• Main reservoir in the Gullfaks Sat.

• 7 wells 2000 Sm3/d. Reserves 12.6 MSm3

1999: F-4 T3H and G-2 T3H in production.

• Surprise ! Produced much less than expected.

• Result: Statfjord Fm. on hold.

2001: G-3 T2H in production.

• Behave in accordance to new/updated

• expectations. Unexpected gas breakthrough.

2002/2003: IOR project initiated. IOR project inititiated.

Identified problems:

Limited reservoir communication

Gas limitation

8

GFS Statfjord Challenge:

• Complex reservoir with low recovery, goal +18% (LTP 2003-2008)

• PDO – 12.6 MSm3. Today 5.4 MSm3

• Increasing GOR -> reduces the oil rates.

Aggressive search to increase recovery factor:

EXTENDING THE LIMITS - STEP BY STEPS

• Additional perforation of G-2 H and F-4 H in lower Statfjord (summer 2003)

• G –1 H with DIACS (2004)

• G –2 YH MLT with DIACS (2004)

• F –2 YH MLT with DIACS (2004)

Currently planning

• GI with RMC (MLT ?) (2006)

454000 455000 456000 457000 458000 459000 460000 461000

6778000

6777000

6776000

6775000

6774000

6773000

6772000

6771000

6770000

461000460000459000458000457000456000455000454000

6770000

6771000

6772000

6773000

6774000

6775000

6776000

6777000

6778000

KILOMETERS 0 1 2 KILOMETERS1:30000

D

E

FGLM

2

16

21

3875

30

32Aô

33

G-2T3H

L-3H

L-4H

3302

G-3HT2

E-4H

F4AHT3

G-1H

G-2Y2H

A3

A2

A1

A4

A6

A5

3 50 0

0

065

3

0

9

04 04

51

2

21

3875

3300

L-4H

3343

F-2Y1H

F-2Y2H

FS1

FS2

FS2.1

FS2.5

FS2.3

FS2.3

FS3

FS3.7

FS3.3

FS3.2FS3.1

FS3.4

FS3.5

FS4

FS4.2

FS4.4

FS4.3

FS4.6

FS4.5

FS4.1FS5.1

FS8

FS8.2FS9 FS8.1

FS8

FS7

FS2.2

FS3

FS5

FS_North_bound

G-3 Y2H

G-3 Y3HG-3 Y3HT2

G-3 Y3HT3 OW

9

Development of GFS Statfjord reservesGullfaks Sør Statfjord

0

5

10

15

20

25

30

35

40

45

PDO 1997 1998 1999 2000 2001 2002 2003 2004

Date

STO

OIP

+con

d (M

Sm3)

0

5

10

15

20

25

30

35

40

45

Rec

over

y Fa

ctor

(%)

STOOIP Oil reserves Recovery Factor

F-4 / G-2 drilled

DIACS / MLTG-3 drilled

10

Gullfaks Area Structural Depthmap – Base Cretaceous

Gullfaks 1 1

Gullfaks South 4 0

Rimfaks 0 1

Topas 1 0

Gullfaks DIACS Wells

New ”Old”

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Well Month/Year Completed Field - Formation

G-1H 02/2004 Gullfaks South – Statfjord fm

C-43 04/ 2004 Gullfaks – Statfjord fm

G-2YH 05/2004 Gullfaks South – Statfjord fm

F-2Y1H/F-2Y2H 11/2004 Gullfaks South – Statfjord fm

C-46 01/2005 Topas – Brent

D-3CH 05/2005 Gullfaks South – Brent fm

New DIACS Wells in the Gullfaks Area

G-1H: G-1H: Two zone DIACS with swell packers. Two zone DIACS with swell packers.

C-43: C-43: Two zone DIACS with swell packers. Two zone DIACS with swell packers.

G-2AHG-2AH/G-2YH: G-2YH: MLT with DIACS control of two branches. MLT with DIACS control of two branches.

F-2Y1H/F-2Y2H: MLT with DIACS control of two branches.F-2Y1H/F-2Y2H: MLT with DIACS control of two branches.

C-46: C-46: Four zone DIACS with swell packers. Four zone DIACS with swell packers.

D-3CH:D-3CH: Two zone DIACS with swell packers. Two zone DIACS with swell packers.

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Why MLT and Remote Monitoring & Control?• Poor reservoir communication and structural complexity More drainage points reduces

the uncertainty.

– The need for more drainage point is clearly based on the STOOIP and estimated volume pr. well.

– A smart well and MLT well will be more robust for the geologic complexity and uncertainty in the reservoir.

• More drainage points

– will increase the estimated production pr well

– expose more of the reservoir:

• minimize the drawdown

• extra reservoir penetrations also allows access to reserves that otherwise would be likely to be left behind.

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Why MLT and Remote Monitoring & Control?• Production experience.

– Want to keep old wellbore

– Verify contribution from each branch

– Optimize, if possible, the contribution from each branch, different drawdown and GOR

– Adjust production from different zones by surface operated valves.

– Clean-up of well easier with DIACS

– More flexibility when co-producing with the other wells

– Natural gas lift

• Limited number of slots

• Aquire more data about pressure communication in the reservoir.

• Smart well technology is an insurance and it provides more data.

• Reduces the need for expensive well interventions

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34/10 – G-1 H

30” section shoe

26” section shoe

17 1/2” section shoe

12 1/4” section shoeTD

Lower Statfjord Formation.

Nansen/ Eiriksson 2 Member.Lunde Fm

Oil producer in segment A3 Well lies 30 m above OWC Approx. 1000 m reservoir section (50/50 lower and

upper Statfjord) External zone isolation performed with open hole zone

isolation Swell packer set in Nansen Pre-drilled liner

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Gullfaks field – Statfjord I-1 segment

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Gullfaks cross section – I1 Statfjord Fm.

Waterinjection

Prod/gas inj.

C-43T2 Completed with a two zone DIACS

Production start 20 April 2004 C-16

B-40A

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C-43T2 - Completion Schematic

Pressure gauge

Two zone control

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DIACS from Schlumberger

•Adjusting production from different zones by surface-operated valves•Operated by applying hydraulic pressure from surface and bleeding it back.•Flow area from 0,055 in2 to 8,67 in2 •Requested position verified by measuring bled back volume.

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G-2 YH MLT with zone control Oil producer in segment A4 Well lies 20 m above OWCApprox. 1640 m reservoir section (50/50 L/U Statfjord) St reservoir as prognosed. Absence of P2 segment. Completed as MLT with branch control Predrilled liner

Planar Dual Lateral; Level 4; Ranking E-1-PN-S/4-NR-RMC The sidetrack penetrates the gas cap which is isolated

by stage cementing.

RMC9 5/8” shoeHollow Whipstock

perforated before uppercompletion

4,5” tubing

Port collar

Cement into thejunction

Packer Predrilled liner

RMC9 5/8” shoeHollow Whipstock

perforated before uppercompletion

4,5” tubing

Port collar

Cement into thejunction

Packer Predrilled liner

Cement into thejunction

Packer Predrilled linerPredrilled liner

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Why hollow whipstock ?

• Simple and well known operations.

• Not necessary to get the lateral liner to TD.

• Can impose high loads on the lateral liner while RIH.

• Level 3 with swell packers or level 4 if necessary.

• Loss of access to motherbore tolerable because:

– Access to motherbore blocked anyway by the RMC.

– Access after pulling completion not very desirable. New lateral is a more likely

option.

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Cost elements

0

50

100

150

200

250

300

Mainbore costs Lateral incrementalcosts

MN

OK

Drill to top reservoir

Run upper completion

D&C reservoir section

ML & RMC costs

D&CReservoir section

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Production profile one vs. two branches

• Eclipse simulations used for justification of MLT

• Decision tree, evaluating well concept used.

• Increased production and accelerated effect.

• Possible to produce from areas of low productivity which otherwise would be left behind.

• Limited reservoir communication, need for more drainage points.

• Mitigate gas breakthrough.

Extra production each year with a MLT

-100000

100000

300000

500000

700000

900000

1100000

1300000

2003

2004

200 5

200 6

2007

200 8

200 9

201 0

201 1

201 2

201 3

Year

Oil

prod

uctio

n Sm

3

Prod oil G-2AH Prod oil G-2MLTKum: G2AH Cum: G-2MLT

Field profileAcceleration effect for MLT

0

500

1000

1500

2000

2500

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

0

1000000

2000000

3000000

4000000

5000000

6000000

7000000

Ref case oil rate BC oil rate

Ref case cum oil BC cum oil

Extra production each year

-200000.00

0.00

200000.00

400000.00

600000.00

800000.00

1000000.00

2003 2004 2005 2006 2007 2008 2009 2010

Year

Oil

prod

uctio

n Sm

3

F-2 H North F-2 H South F-2 H Mlt

F-2 H North cum Cum .F-2 H South Cum. F-2 H Mlt

23

Total reservoir exposure vs total rig days

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 100 200 300 400 500 600Rig days

Met

ers

ML wells

Total reservoir exposure vs rig days

0

5

10

15

20

25

30

35

40

45

Rese

rvoi

r met

ers

[m]

G-2HT3 F-4AHT3 G-3HT2 G-1H G-2Y2H F-2H

Single wellsML wells

0.2050.413

0.6810.976

1.269

1.724

2.276

0.00

0.50

1.00

1.50

2.00

2.50

1999 2000 2001 2002 2003 2004 2005Date

MSm

3 pr

odus

ert

24

Swell packers• Perform external zone isolation between the

reservoir and the pre-drilled liner.

• External zone isolation performed with open hole

zone isolation.

• Gamma ray and calliper log run.

D-3CH

350

360

370

380

390

400

410

420

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00

Pres

sure

, bar

Annulus

Tubing

5

6

7

8

9

10

11

12

13

5030 5035 5040 5045 5050 5055 5060 5065 5070

Depth, m MD RKB

Hol

e di

amet

er, i

n

0

50

100

150

200

250

300

350

400

GRMax ID

Min ID

GR

Swell packer

25

Conclusion Well solution chosen: Long horizontal wells, include entire formation.MLT : Expose more of the reservoirSmart: Remotely operated downhole valvesSimple: with respect to operations as well as long lifetime for wells (10 years)Swell packers performs the necessary isolation, but it is not enough to only let the packer swell in OBM, it need produced HC to isolate.

Better data gatheringPressure gauge failureProducing from separate zones give valuable reservoir information.

Limited production rate improvementMitigate gas breakthrough and balance production from ML legs Smart wells an insurance and provides data to help in further development of the field

Limited number of slotsUpgraded reservesMLT well solution accelerates the reserves, gives better NPV, thus further development of low recovery reservoirs is possible.

The experience gained with smart and ML wells has encourage further development of GFS Statfjord.

26

Reservoir quality• Geological cross section

Permeability

Good sands: 100-2000 mD

Poor sands: 1-100 mD

50 - 50 in the reservoir

Porosity 20 %

Limited reservoir communication

27

Assessment of smart well solutionsWell Solution Why Assessment of result

G-1H RMC Zone control • Gained important information from a complex reservoir and contribution from

“poor” sands.

• Individual tests of the two zones have been performed.

•Have not choked back the gas- since it comes from the zone which contribute the

most (85% of the total production)

• In the future the plan is to choke the gas to increase the outtake from the rest of

the sand.

• Zone 1 is shut-in to prevent further pressure drop before drilling the next well.

• Limited production increase

28

Assessment of smart well solutionsWell Solution Why Assessment of result

G-2YH RMC in

junction

MLT with

branch control

• Both legs are contributing to production.

• No isolation between the two branches, due to leaking QMP isolation packer

• The well works as a normal well without DIACS, thus no extra production

increase using DIACS.

• DIACS helped in clean-up of the well

• Use of perforated whipstock has probably given a extra gain from the

motherbore which we would not have been able to produce from (produces from

an isolated segment)

29

Production experience: total oil rateProduction experience for GFS Statfjord wells

0

500

1000

1500

2000

2500

3000

apr.

99

aug.

99

des.

99

apr.

00

aug.

00

des.

00

apr.

01

aug.

01

des.

01

apr.

02

aug.

02

des.

02

apr.

03

aug.

03

des.

03

apr.

04

aug.

04

des.

04

apr.

05

aug.

05

Date

Tota

l oil

rate

(Sm

3/d)

0

500 000

1 000 000

1 500 000

2 000 000

2 500 000

Cum

ulat

ive

oil p

rodu

ctio

n (S

m3)

F-2YH11.2004

G-2YH07.2004

G-1H02.2004

F-4AT3HAdd. Perf10.2003

G-3HT207.2001

G-2HT3/F-4AT3H04.1999