nns - experiences on low cost … - experiences on low cost interventions to boost production in...

© 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


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


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


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


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)


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


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


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


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


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


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)

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