nns - experiences on low cost … - experiences on low cost interventions to boost production in...
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© Marc Roussel / Total
NNS - EXPERIENCES ON LOW COST INTERVENTIONSTO BOOST PRODUCTION IN MATURE FIELDS
Author and speaker: Davide Mazzucchelli, Co-authors: Kvinnsland Steinar, Johann Frangeul, Tomi Sugiarto, Andika Sulaiman, Evgeny Eropkin – Total E&P UK
DEVEX 2015 - 21st May 2015
NNS - EXPERIENCES ON LOW COST INTERVENTIONS
TO BOOST PRODUCTION IN MATURE FIELDS
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 2
Topics:
• Examples of interventions for production optimization in mature fields in NNS:
– Ellon 1 – Subsea well WSO
– Dunbar D15 – Re-perforation
– Alwyn Triassic – Re-perforation
– Alwyn Brent – Concentric gas lift
• Feedback and lesson learnt
Multi-Disciplinary work (Co-Authors and acknowledgement):
• Reservoir: Kvinnsland Steinar, Johann Frangeul, Trevor Coombes, Ombana
Rasoanaivo, Simon Batoumeni, Ali Parsa, Onyeka Onyia, Emilien Maxant
• Well intervention: Tomi Sugiarto, Andika Sulaiman
• Well performance: Evgeny Eropkin, Valentina Zaccardi, Amelie Descousse
3NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015
ALWYN AREA - FIELDS LOCATION
Total op. acreage
Total non op. acreage
TEPUK core areas
Central Graben
SE
AL 3
4”
to
Bacto
n36” to Cruden
Bay
FUKA 2
4”/3
2”to
St F
ergu
s
Northern North
Sea
West of Shetlands
Total op. acreage
Total non op. acreage
TEPUK core areas
Central Graben
SE
AL 3
4”
to
Bacto
n36” to Cruden
Bay
FUKA 2
4”/3
2”to
St F
ergu
s
Northern North
Sea
West of Shetlands
● Location
- 135km east of Shetland
- ~ 140 m water depth
● North Alwyn Field discovered in 1975
● First Oil 1987
● Greater Alwyn area now consists of 8 main fields
● Total E&P - 100% ownership
Dunbar
Alwyn North
MAIN FIELD OVERVIEW
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 4
Top Triassic Depth Map
ALWYN area fields, main
features:
• Jurassic – Triassic sequence
• Reservoirs: Brent, Statfjord & Triassic
• Gas – Gas Condensate and Oil
• Mature assets with declining production
• Subsea tie-back (Ellon, Grant, Forvie line..)
• About 50 wells still producing
• Ageing facility but...
• ... Still activities planned:
• Drilling activities
• Production optimization
Alw
yn
Du
nb
ar
POP - TOTAL PROGRAMME D’OPTIMISATION DU PLATEAU
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 5
2013-2014 actions were promoted:
• TEPUK launched ‘Mission 2015’ to increase affiliate production rate
• Total E&P ‘POP - Programme d’optimisation du plateau’ to implement actions and
methods to meet production targets worldwide
NNS production optimization - methodology applied:
• Screen all the wells and identify residual potential
• Identify and rank candidates for well intervention
• Perform technical feasibilities
• Propose and implement the interventions
• Review results and apply lesson learnt for new interventions
Mandatory steps:
• Multi-disciplinary brainstorming
• Review technology available in the market
• Integrate experiences from different Total affiliates
ELLON A01 2014 INTERVENTION
A01 general:
– A01 subsea well producing since 1998
– Cum Prod ~ 22 MBOE
– Well was producing with high water cut
– Multi-layer reservoir – PLT in 2000 proved lower Brent watered out
Objective:
– WSO of lower Brent
Operations - Sep 2014 :
– A LWI with a vessel to:
1. Re-perf: Tarbert T2-T3 (3392-3416 mMD)
2. WSO plug and cement to isolate T1 and Ness
• Production Gain ~ 4000 boepd
• Water reduced from 3800 bwpd to 700 bwpd
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 6
R
e
p
e
r
f
W
a
t
e
r
G
a
s
Plug and cement 3 m
RISKY SUBSEA OPERATION –REWARDING ACTIVITY
Prod. Gain
~0.5 MSm3/d
A01 - 2014 INTERVENTION: TECHNOLOGY
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 7
Job Design:
1. Re-perforation: Newer generation guns used
1994: 23.2” API Pen, 0.28” EH
2014: 36.0” API Pen, 0.34” EH
2. WSO: Plug and new cement
• Cement on the top of plug (Diff pressure ~7.5x standard cement)
» Work with Schlumberger to develop High Shear Cement
» First application in UK: designed for 5000 psia + safety factor
3. Clean up procedure strategy:
• Apply gradual opening & closing well to minimize cement degradation
4. Long term memory gauges installation
Expected at least ~80 days data record - to be retrieved in the next LWI campaign
TECHNOLOGIES NOT AVAILABLE IN THE PAST COULD BRING VALUE TODAY
Cement compressive strength test
DUNBAR – D15Z RE PERFORATIONS (BRENT)
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 8
D15Z DUS, Upper and Lower Brent reservoirs perforated in 1997
Severe production decline observed since 2011
Objective:
• 100 m re-perforation job.
• Baseline & post-job PLT also acquired.
Operations – Apr. 2014
• Newer generation guns used
• Duration: 9 days (perf. only)
Results
• Overall Productivity Index x 2.0 on re-perforated layers
• Qoil increase from 900 to 2000 bbl/d ( 3000 boepd)
• Cum. Gain estimated at 280 kboe so far
GR Phi
Perfos
DUS
142 MD.m
Upper B.
1120 MD.m
Lower B
10 MD.m
Re-perforations
PermRes
D15 - PLT RESULTS –ANALYSIS
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 9
PLT highlights:
1. Further residual potential present in Brent multi-layers reservoir
2. Tight sand production did not improve with re-perf – other tech. needed
(frac jobs?)
ALWYN TRIASSIC
N35 RE-PERFORATIONS
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 10
Objective:
• Restore the productivity of the high productive layers with
observed PI degradation based on PLT analysis
• Targets for N35: LB4, C1
Operations – Nov/Dec. 2013
• Total re-perforated length: 27 m
• Operation time: 7 days (perf. only)
• Guns type – Deeper penetration
Results
• Gas rate stabilized at 220 kSm3/d vs 150 kSm3/d before the
re-perforation
Stabilized Gain ~ 70Ksm3/d of Gas (~500 boepd)
Technical Reserves gain estimates ~ + 2.5 Mboe due to
delayed liquid loading
• PI increment of ~3.5 times
Gas R
ate
(S
m3/d
)
Re-Perf
QGas = 220 kSm3/d
QGas = 150 kSm3/d
-
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
PI
(Sm
3/d
/ba
r)
Date
N35
LB4 C1
1 SUCCESSFUL OPERATION CAN PAY FOR A CAMPAIGN
ALWYN TRIASSIC
N38 RE-PERFORATIONS
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 11
Objective:
• Restore the productivity of the high productive layers with
observed PI degradation based on PLT analysis
• Targets for N38: LB2, C1
Operations – Aug. 2014
• Total re-perforated length: 35 m
• Operation time: 10 days (perf. only)
• Guns type - Deeper penetration
Results
• Global Well Head pressure increase of 20 bars during
perforation job
• No evident gain observed on the production
• Liquid column in the well plan to lift the well with CT
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1998 1999 2000 2001 2002 2003 2004 2005 2006
PI
(Sm
3/d
/ba
r)
Layer Pressure
UB4 LB6 LB2 C2 C1
C1LB2
Ga
s R
ate
(S
m3
/d)
Re-Perf
RESULTS STILL UNCLEAR
ALWYN BRENT EAST – CONCENTRIC GAS LIFT
12NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015
N10 / N11
Gas lift for restart
purposesN3 / N26 / N18
Gas Lift Necessary for
ProductionN1 / N9
Gas lift to Limit Water-
cut of crestal wells +
decrease pressure
N31 / N36
Gas Lift Necessary
for Production
“Virtuous circle” :
Gas from MGI is liberated form unswept oil.
It help wells to produce, it decreases pressure, it liberates even more gas from oil
N10 / N11
Gas lift for restart
purposesN3 / N26 / N18
Gas Lift Necessary for
ProductionN1 / N9
Gas lift to Limit Water-
cut of crestal wells +
decrease pressure
N31 / N36
Gas Lift Necessary
for Production
“Virtuous circle” :
Gas from MGI is liberated form unswept oil.
It help wells to produce, it decreases pressure, it liberates even more gas from oil
BlowdownDeplete the reservoir to liberate gas from remaining oil
=> Produce HC through existing wells
First blowdown project started in 2004 without
artificial lift leads to mixed results:
• Good results for 2 main producers (most crestal wells) but
3 wells died rapidly (high WCT) and 2 wells did not restart
This first phase highlighted the necessity to have
artificial lift for a successful blowdown project
Concentric Gas Lift (CGL)retained as the most
appropriate artificial lift solution
Blowdown with artificial lift started in 2014 with 4
wells
• 2 Water producers (N9 and N1) to accelerate depletion
• 2 HC producers to increase recovery factor
• N3 HC potential = 3000 boepd
• Started in May 2014 – Cum. Prod. > 0.5 MMboe
• N10 HC potential = 2000 boepd
• Started in April 2015
Fifth candidate under study
CGL WO completed
PROGRAM – WAY FORWARD
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 13
Alwyn
• POP opportunities during Alwyn Rig Warm Stack
• 6 operations on Triassic wells planned in Summer 2015 for expected gains between 2000
to 6000 boepd
• 5+ operations in the portfolio for 2016+
Dunbar
• Well interventions compete with Phase IV drilling campaign
• Technical feasibility for operations (re-perforation and WSO) ready in case of opportunity
windows
• Frac job under investigation to produce the tight sands
Subsea
• Interventions very costly but high production potential for good candidates
LESSON LEARNT / CONCLUSIONS
NNS - Experiences on low cost interventions to boost production in mature fields - 21st May 2015 14
Integrated approach mandatory for the success of the operations (GSR - Well
Perf. – Well intervention)
Technology not available in the past could be applied to enhance production
today
Operations relatively cheap:
• pay out time very quick
• 1 successful operation (D15 & N35) can pay for a campaign
• risk worth to take!
Valuable data acquisition (D15 & Triassic PLTs) may help the understanding of
the reservoir:
• Damages or un-perforated layers potential still in place in multi-layer reservoirs
• Dunbar tight sands re-perf. did not improve performances – other technique may be
applied to unlock the potential (frac jobs)