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