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Task 4: StimulationEconomics and PWRI
TerraTek, Inc.Heriot -Watt UniversityTriangle Engineering
Duke Engineering and Services, Inc.
eFirst TechnologiesGas Research Institute
Advantek, International, IncVIPS
Data
Issues
Confirm / Revise / DevelopTechnical Methods
ExperienceDatabase
‘Other Company’Contacts / knowledge
SoftwareBest Practices
Toolbox
PWRI
Issues
Data
Confirm / Revise / DevelopTechnical Methods
ExperienceDatabase Best
Practices
Toolbox
Software
‘Other Company’Contacts / knowledge
Cost Cost
CostCost
PWRI and Economics
Issues
Data
Confirm / Revise / DevelopTechnical Methods
ExperienceDatabase Best
Practices
Toolbox
Software
‘Other Company’Contacts / knowledge
Risk Cost vs Benefit
Cost vs Benefit Risk
PWRI, Economics and Stimulation
Drivers for Produced Water Re-Injection
Purposes:
WATER INJECTIONDRIVERS:
PWRI DRIVERS:
Producedwater
disposal Disposalzone
Waterinjection
Reservoir Management:- Pressure Maintenance
- Sweep
Options:SWI/AWI
(lowest costsource of water)
PWRI
Sub-surfacedisposal
(injection)
Better Treatment& surface disposal
Oilzone
Disposalzone
- Need Additional Injection Water
- Environmental Issues- Company Policy
- Legislation- Other
Water Injection
• Lowest cost water source used early in project life
• Produced Water becomes available later on
• Additional surface facilities/equipment normally required for move to PWRI operation.
• Opex e.g. pump maintenance will change
• Facilities operation mode will be decided by cost/benefit analyses (e.g. commingled or separated injection)
• Higher pressure pumps, new or converted wells may be required in order to re-inject increasing PW volumes
PWRI Economics - The Way AheadNext Presentation (Paul Van Den Hoek)
PWRI Project - Decision Tree
Injection Process
in operation (SW/AW)
PWRIRequired(at later stage)?
Segregated
Sufficient pump
capacity?
Conversion/ Addition of surface facilities
Yes
Commingled
Operationmode
(cost/benefitanalysis)
Not yet
No
Enough InjectionWells ?
Additional injectionwells required
(new/converted)
Addition of PWRI System
Cost
Cost
Cost
PW available?
Water forearly
injection?
Yes
No
Higher Pressurepumps
Cost
Yes
No
Yes
OKOK
Water Injection
• Lowest cost water source used early in project life
• Produced Water becomes available later on
• Additional surface facilities/equipment normally required for move to PWRI operation.
• Opex e.g. pump maintenance will change
• Facilities operation mode will be decided by cost/benefit analyses (e.g. commingled or separated injection)
• Higher pressure pumps, new or converted wells may be required in order to re-inject increasing PW volumes
PWRI Economics - The Way AheadNext Presentation (Paul Van Den Hoek)
PWRI - Technical & Cost Implications
• Can we generate a “planning figure” for loss of injectivity due to conversion to PWRI (e.g. 20%)?
• It depends on formation, thermal effects & water quality (oil/solids) e.g. PEA 23 equation
• Risks e.g. what are the disposal alternatives of the produced water if injectivity is insufficient?
PWRI - Impact Injectivity Damage
No Damage
Additional water treatment
facilitiesIntermittent?
No
InjectionLoss fully
recovered ?Additional injection
wells
Cost
Damage?
Water Quality?
Good
Poor
HigherPressurepumps
Yes
No
Yes
OKOK
Net Cost
Net Cost
Cost
Cost
Cost
On goingdamage ?
Yes
No
(Repetitive)Chemical
Stimulation
MechanicalStimulation Cost
FacilityOptions
Stimulation
PWRI - Technical & Cost ImplicationsInjectivity
3. Or facilities for better water quality from start? Costs? 3. Or facilities for better water quality from start? Costs?
1. Accept lost injectivity?(new wells? Costs?)
1. Accept lost injectivity?(new wells? Costs?)
Time
2. Regular stimulation? Efficiency? Costs?2. Regular stimulation? Efficiency? Costs?
Water Management
• What is “value” of extra water injected
• Water needs to become a tangible benefit in terms of pressure support / sweep rather than “just a cost”
• Understand Interplay between water injectors and producers (also required for Intelligent Injectors)
• Where can a limited amount of injection water be most beneficially used– (New) flowstream representation of reservoir
simulation results (e.g. FLOWVIS from Geoquest) simplify this
What is lowest cost / least risk option?
• Cost Example from data base (1):
Corrosion Management
– * Deferred oil
Million $ / year Cost of corrosioncontrol
Change NPV
Do nothing 2.1 - -
Dump off spec water 1.9* 0.2 - 0.7
Modify plant 1.3 0.8 + 1.1
Modify plant + dump 1.9* 0.2 + 0.31
Cost Example from data base (2):
• Bypass part of water treatment system?
– Costs in Million $ / year
– What happens during plant upset:
Saving Potential cost NPV
Do nothing 0 -
Bypass filters 160 See Below
Reaction time Where is thefluid?
Remedial action Risk Cost
< 1 minute Surface Circulate out % -
1 < 10 minutes Wellbore Backflush % 125
> 10 minutes Formation Reperforate % 1500
PWRI - Technical & Cost Implications
• Option 1: Costs of Mitigation
– Derive from Paul Van Den Hoek’s proposal for: PWRI Economics - the Way Ahead
• Option 2: Stimulation treatments needed to restore injection
• How do we define success?
Is stimulation the lowest cost option?
•Compare costs continuing damage & acid stimulation
ELF PICTURE
C-02-20-018-15Injectivity Index
-10.00
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
6.00
8.00
10.00
Jun-
68
Oct
-69
Mar
-71
Jul-7
2
Dec
-73
Apr
-75
Aug
-76
Jan-
78
May
-79
Oct
-80
Feb-
82
Jul-8
3
Nov
-84
Mar
-86
Aug
-87
Dec
-88
May
-90
Sep-
91
Jan-
93
Jun-
94
Oct
-95
Mar
-97
Jul-9
8
Dec
-99
Apr
-01
Date
II (b
bl/p
si-da
ys)
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
RII
(p
si-da
ys/b
bl)
II RII
Acid Wash 20 Oct 1971
Jet, Re-Perf. 29 Sep 1971
Jet, Acid Wash &Squeeze, Re-Perf. 27 Feb 1980
Is stimulation the lowest cost option?
•Include risk of “technical” failure!
ELF PICTURE
Hall PlotC-14-07-018-15
0.0E+00
1.0E+06
2.0E+06
3.0E+06
4.0E+06
5.0E+06
6.0E+06
7.0E+06
8.0E+06
9.0E+06
1.0E+07
1.1E+07
1.2E+07
0.0E+00 1.0E+06 2.0E+06 3.0E+06 4.0E+06 5.0E+06 6.0E+06 7.0E+06 8.0E+06
Cumulative Injection Volume (BW)
Pre
ssu
re-T
ime
Su
mm
atio
n (
psi
-day
s)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Mon
thly
In
j. B
HP
(p
si)/
Rat
e (b
pd
)
Hall BHP Rate
Jet, Re-Perf. 5 May 1996
Acid Squeze 5 Jan 1977
Is stimulation the lowest cost option?
•Compare costs continuing damage & acid stimulation
ELF PICTURE
ELF-3 W-1
0.00E+00
2.00E+05
4.00E+05
6.00E+05
8.00E+05
1.00E+06
1.20E+06
1.40E+06
1.60E+06
1.80E+06
0 2,500,000 5,000,000 7,500,000 10,000,000 12,500,000
Cummulative Injection Volume (BBL)
Pre
ssu
re T
erm
(ps
i*d
ays)
0
2,500
5,000
7,500
10,000
12,500
15,000
17,500
20,000
22,500
BH
P (p
si)
& I
njec
tion
Rat
e (B
PD
)
HallInj. Pressure "BHP"Injection RatePWAcidification Jun/95Acidification Sep/95Acidification Nov/95Acidification May/96Acidification Oct/96Acidification Nov/96Acidification Aug/97Acidification Dec/98Acidification Apr/99Acidification May/99Acidification Jun/99Acidification Jul/99Acidification Aug/99Acidification Sep/99Acidification Oct/99Acidification Oct/99Acidification Nov/99Acidification Jan/00Acidification Jan/00
HALL PLOT
Acid treatments
PWRI - Techno / Economic Evaluation
• How do we define success?
– Qualitative view (Extremely / Yes / No)
– Achieve short term injection target often critical
– Recognise other well / injection system limitations
(discounted stimulation index based on Hall plot?- see next slide)
– Economics concentrate on “extra” water injected compared to “do-nothing base case”?(i.e. similar concept as used for evaluation of
production well stimulation)
Stimulation Economics - The Way Ahead
• Prepare best practice using “Stimulation Index” based on “value” of discounted net extra water injected
• Compare with cost of stimulation and other mitigation strategies
• Include stimulation in any larger study (Use same methodology)
• Request “typical” costs for “most complete” wells in database
PWRI - Technical & Cost Implications
Time
InjectivityExtra water injectedExtra water injected
Repetitive Acidising of Sandstones
•Often shows decreasing success
•Damage Location - Placement techniques
•Stimulation fluid selection