Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
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 evolution
Case for charge testing
Test set-up / test conditions
Charge test results
Findings charge testing
Impact concepts
Conclusions and way forward
Nederlandse Aardolie Maatschappij BV 3Month 2010Restricted
Well concept evolution
Netherlands / Southern UK sector scene setting
Mature area, remaining gas/oil accumulations small size (0.2 – 1
BCM)
Early 2000’s: “step change” in costs required
3
Significant changes (down
sizing) required in well design, rig
selection, well functionality and
surface lay-out in order to meet
challenge
Nederlandse Aardolie Maatschappij BV 4Month 2010Restricted
Well concept evolution – 1st step
Typical 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 sizes
simple wellhead
3½” cemented completion
2” perf guns, static balanced / slight
underbalance for trigger interval
� Concept worked for no. of
years BUT next step ?
4
Old design current design
Nederlandse Aardolie Maatschappij BV 5Month 2010Restricted
Well concept evolution – the next step ?
5
FALLBACK
Ο
Current base case
Ο Ο
3 ½” tbg, cemented in 6” – or 4 7/8” OH
2” guns
Proposed “slim” case, low permeability
Proposed “slim” case, high permeability
2 7/8” tbg,
cemented in
4 7/8”- or 3
15/16” OH
small guns:
1 9/16” or
1 11/16”
3 ½” * 2 7/8”
tbg,
cemented in
4 7/8”- or 3
15/16” OH
small guns:
1 9/16” or
1 11/16”
Driven by swell data assumptio
ns
Nederlandse Aardolie Maatschappij BV 6Month 2010Restricted
Slim well concept – impact gun size (base modelling)
6
0
20
40
60
80
100
120
140
160
180
200
0 200 400 600 800 1000 1200
FBHP (bara)
Gas rate (Km3/d)
0
100
200
300
400
500
600
Mar-09
Jun-09
Sep-09
Dec-09
Mar-10
Jun-10
Sep-10
Dec-10
Mar-11
Jun-11
Sep-11
Dec-11
Mar-12
Jun-12
Sep-12
Dec-12
Mar-13
Jun-13
Sep-13
Dec-13
Gas rate
Km3/d
DATE
Prod profile
0
20
40
60
80
100
120
140
160
180
200
Mar-09
Jun-09
Sep-09
Dec-09
Mar-10
Jun-10
Sep-10
Dec-10
Mar-11
Jun-11
Sep-11
Dec-11
Mar-12
Jun-12
Sep-12
Dec-12
Mar-13
Jun-13
Sep-13
Dec-13
Gas rate
Km3/d
DATE
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 !!
Nederlandse Aardolie Maatschappij BV 7Month 2010Restricted
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 stress
�Section 2 only, no flow conditions
�Various combinations OH size / tbg – and charge size
�Varying cement thickness
Nederlandse Aardolie Maatschappij BV 8Month 2010Restricted
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
modelling
0
2
4
6
8
10
12
14
0 10 20 30
Do
P,
pe
ne
tra
tio
n,
inc
hDoP 2" charge
DoP, 2" charge, 6"OH
DoP, 2" charge, 47/8" OH
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0 10 20 30
EHD inch
EH, 2"charge, 6" OH
EH, 2"charge, 4 7/8"OH
Sample no �Sample no �
Nederlandse Aardolie Maatschappij BV 9Month 2010Restricted
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
modelling
0
1
2
3
4
5
6
7
0 5 10 15 20
TC
P p
en
etr
ati
on
, in
ch
TCP, small charge,4 7/8" OH
TCP, small charge,3 15/16"OH
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0 10 20
EH, 4 7/8"OH
EH, 3 15/16"OH
Sample no �
Sample no �
DoP,
inch
EHD,
inch
Nederlandse Aardolie Maatschappij BV 10Month 2010Restricted
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
2
4
6
8
10
12
14
0 5 10 15 20 25 30
Do
P,
inc
h
DoP impact cement thickness
2" DoP, 4 7/8" OH
2" DoP, 6" OH
"small" DoP, 3 15/16"OH
"small" DoP, 4 7/8" OH
Sample no �
Nederlandse Aardolie Maatschappij BV 11Month 2010Restricted
Findings charge testing (2)
Futher analysis of results
�Centralisation / stand-off impact: significant and hence to be
included, not directly included in original modeling
�Overall “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 modeling
6” OH 9” 7.7”7”
4 7/8” OH
11” 9.6”
EH 0.19” 0.17” 0.22”
Eff, % 50 50 80
Small charge
vertical deviated Used for original modeling
4 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
Nederlandse Aardolie Maatschappij BV 12Month 2010Restricted
Impact charge testing on well concept selection
0
20
40
60
80
100
120
140
160
180
200
0 200 400 600 800 1000
FBHP(bara)
Gas rate 1000m3/d
Inflow Performance Relationship
2" charge, base model
small charge, base model
2" charge, 6" OH, test results
2" charge, 4 7/8" OH, test results
small charge, 4 7/8" OH, test results
small charge, 3 15/16" OH, testresults
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.
Nederlandse Aardolie Maatschappij BV 13Month 2010Restricted
“Economics” : Impact charge testing on well concept selection
243
234
239241
216
227
200
205
210
215
220
225
230
235
240
245
250
Mm3 Cumulative Gas Production
BAS
EBAS
E
2” charge Minor Impact
Small charge
Major Impact
Nederlandse Aardolie Maatschappij BV 14Month 2010Restricted
Conclusions
Charge testing results
�Reducing 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-
estimated
�potential 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 forward
�Carry out gun survival tests for 2” guns inside 2 7/8” tubing � if
Nederlandse Aardolie Maatschappij BV 15Month 2010Restricted