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