nederlandse aardolie maatschappij bv1november 2012 restricted charge testing for well concept...

Nederlandse Aardolie Maatschappij BV 1November 2012Restricted

Charge testing for well concept selection

November 2012

Eelco Bakker, Al Zanimonsky, NAM

Mark Brinsden, Shell

EWAPS 12 - 6

Presented at 1st European & W African Perforating Symposium, Amsterdam 7 – 9 November 2012

Nederlandse Aardolie Maatschappij BV 2Month 2010Restricted

content

Well concept evolutionCase for charge testingTest set-up / test conditionsCharge test resultsFindings charge testingImpact conceptsConclusions and way forward

Nederlandse Aardolie Maatschappij BV 3Month 2010Restricted 3

Well concept evolution

Netherlands / Southern UK sector scene settingMature area, remaining gas/oil accumulations small size (0.2 – 1 BCM)Early 2000’s: “step change” in costs required

Significant changes (down sizing) required in well design, rig selection, well functionality and surface lay-out in order to meet challenge


Well concept evolution – 1st stepTypical well data

Reservoir depths: 2800- 4600 mAH (1800 – 3500 m TVD) Reservoir pressure 250 – 360 bar (undepleted) Reservoir temperature 100 - 125 deg C permeability : <1 - 50 mD, porosity 8 - 20 %

typical features:reduced csg sizessimple wellhead3½” cemented completion2” perf guns, static balanced / slight underbalance for trigger interval

Concept worked for no. of years BUT next step ?

Old design current design


Well concept evolution – the next step ?

FALLBACK

Ο

Current base case

Ο Ο

3 ½” tbg, cemented in 6” – or 4 7/8” OH2” guns

Proposed “slim” case, low permeability

Proposed “slim” case, high permeability

2 7/8” tbg, cemented in 4 7/8”- or 3 15/16” OHsmall guns:1 9/16” or 1 11/16”

3 ½” * 2 7/8” tbg, cemented in 4 7/8”- or 3 15/16” OHsmall guns:1 9/16” or 1 11/16”

Driven by swell data

assumptions


Slim well concept – impact gun size (base modelling)

0 200 400 600 800 1000 1200020406080

100120140160180200

Gas rate (Km3/d)

FBHP (bara)

Mar-09

May-09

Jul-0

9Sep-09

Nov

-09

Jan-10

Mar-10

May-10

Jul-1

0Sep-10

Nov

-10

Jan-11

Mar-11

May-11

Jul-1

1Sep-11

Nov

-11

Jan-12

Mar-12

May-12

Jul-1

2Sep-12

Nov

-12

Jan-13

Mar-13

May-13

Jul-1

3Sep-13

Nov

-130

100

200

300

400

500

600

DATE

Gas rateKm3/d

Prod profile

Mar-09

May-09

Jul-0

9Sep-09

Nov

-09

Jan-10

Mar-10

May-10

Jul-1

0Sep-10

Nov

-10

Jan-11

Mar-11

May-11

Jul-1

1Sep-11

Nov

-11

Jan-12

Mar-12

May-12

Jul-1

2Sep-12

Nov

-12

Jan-13

Mar-13

May-13

Jul-1

3Sep-13

Nov

-130

20

40

60

80

100

120

140

160

180

200

DATE

Gas rateKm3/d

Cum prod

2” guns

Small guns

IPR

Case for charge testing:based on initial modeling, impact (Q / NPV) of changing to slim completion could be significant needs further clarification test DoP assumptions !!


Charge testing conditions in lab

reservoirUCS = 1000 – 2000 psi (70 –

140 bar)

Res Pressure = 4350 – 5000 psi (180 - 350 bar)

Overburden = approx 9200 psi

(634 bar)

UCS of test sample

Internal Pressure

Field conditions

Confining stress on outside of the sample

Test set-up / test conditions

In order to mimic field conditions as good as possible selected the following parameters: Carbon Tan material (sandstone) internal / confining stressSection 2 only, no flow conditionsVarious combinations OH size / tbg – and charge size

Varying cement thickness


Charge test results 2” charge

Carried out some 33 tests (3 labs, test data randomly plotted !!)Tests in 7” and 4” Carbon Tan cores, both centralised / excentralised.In some tests free gun volume ( FGV) reduced to minimise effect DUB (dyn underbalance)

Data used in original

modelling0 5 10 15 20 25 3002468

101214

DoP 2" charge

DoP, 2" charge, 6" OHDoP, 2" charge, 4 7/8" OH

DoP,

pen

etra

tion

, inc

h

0 5 10 15 20 25 300.14

0.16

0.18

0.2

0.22

0.24

0.26EHD inch

EH, 2" charge, 6" OHEH, 2" charge, 4 7/8" OH

Sample no Sample no


Charge test results small charge

Carried out some 17 tests (3 labs, test data randomly plotted !!)Tests in 7” and 4” Carbon Tan cores, both centralised / excentralised.In some tests FGV reduced to minimise effect DUB

Data used in original

modelling0 2 4 6 8 10 12 14 16 18

0

1

2

3

4

5

6

7

TCP, small charge, 4 7/8" OHTCP, small charge, 3 15/16"OH

TCP

pene

trat

ion,

inch

0 2 4 6 8 10 12 14 16 180.1

0.12

0.14

0.16

0.18

0.2

0.22

EH, 4 7/8" OHEH, 3 15/16" OH

Sample no

Sample no

DoP, inch

EHD, inch


Findings charge testing (1)Futher analysis of results Impact cement thickness clearly seen in majority of

tests (6” vs 4 7/8” OH, 4 7/8” vs 3 15/16” OH)

0 5 10 15 20 25 300

2

4

6

8

10

12

14

DoP impact cement thickness

2" DoP, 4 7/8" OH2" DoP, 6" OH"small" DoP, 3 15/16" OH"small" DoP, 4 7/8" OHDo

P, in

ch

Sample no


Findings charge testing (2)Futher analysis of resultsCentralisation / stand-off impact: significant and hence to be

included, not directly included in original modelingOverall “perforation efficiency” (OH tunnel length/TCP

tunnel length) from tests some 80%, hence efficiency for actual field conditions lower (less optimal conditions for dyn UB) tentatively set @ 50% DoP 2” charge

vertical deviated

Used for original

modeling6” OH 9” 7.7”

7”4 7/8”

OH11” 9.6”

EH 0.19” 0.17” 0.22”

Eff, % 50 50 80

Small charge

vertical

deviated

Used for original

modeling4 7/8”

OH 2.9” 2.4”4”

3 15/16”

OH5.1” 4.3”

EH 0.17” 0.17” 0.17”

Eff, % 50 50 80


Impact charge testing on well concept selection

0 100 200 300 400 500 600 700 800 900 10000

20

40

60

80

100

120

140

160

180

200Inflow Performance Relationship

2" charge, base modelsmall charge, base model2" charge, 6" OH, test results2" charge, 4 7/8" OH, test resultssmall charge, 4 7/8" OH, test resultssmall charge, 3 15/16" OH, test results

Gas rate 1000m3/d

FBHP(bara) Impact 2” charge:

test results impact rel. minor

Higher DoP offset by lower assumed perforation eff.

Impact small charge: impact clear Lower DoP + lower

assumed perforation eff.


“Economics” : Impact charge testing on well concept selection

200

205

210

215

220

225

230

235

240

245

250

243

234

239241

216

227

Cumulative Gas ProductionMm3

BASE BAS

E

2” charge Minor Impact

Small chargeMajor Impact


ConclusionsCharge testing resultsReducing tubing size to 2 7/8” and using smaller charges not

attractive given loss of inflow / recovery this concept no longer pursued !!

Impact perf tunnel efficiency significant Impact cement thickness for smaller charges potentially

under-estimatedpotential impact on selected drilling practices (OH drilling

diameter)Perforation tunnel efficiency possibly overestimated in

original modelling“ideal” lab tests gave results of approx 80%, field

conditions (small clearance, low static UB) far from ideal.Way forwardCarry out gun survival tests for 2” guns inside 2 7/8” tubing

if successful repeat charge testing pursue the tapered 2 7/8” * 3 ½” completion concept using 2” guns.

nederlandse aardolie maatschappij bv1november 2012 restricted charge testing for well concept...

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