Oilgen on Low Salinity AFES 9 Nov 2011

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Low Salinity water injection:

Evaluating the EOR potential

Presentation at the

Aberdeen Formation EvaluationSociety

9 November 2011

Laurent Schirrer, Oilgen Ltd



Motivation: a “forum” more than a

formal presentation

Presentation»

Raise awareness on Low Salinity water injection as anEOR technique

» Practical workflows now exist to evaluate commercialfeasibility

» Specific Challenges for the North Sea

Please interrupt (for clarification only, thank you)

Questions / AnswersWhere the value is added

Followed by: AFES social drinks

Where the value is destroyed ?

AFES November 2011 - Aberdeen



Presenter

Laurent SCHIRRER

» Director of Oilgen Ltd, a reservoir engineeringand subsurface consultancy

» Background in Reservoir Engineering,

Geoscience management, Development» Low Salinity ?

In 2010-2011, consultant subsurface leader on a NorthSea EOR Low Salinity evaluation project




What is Low Salinity water

injection ?

The injection of water of a salinity lower thanthe formation water,for the purpose of

increased oil recovery,either in secondary or

tertiary mode

…when the Enhanced Oil

Recovery (EOR) effectis genuinely caused by

the reduction insalinity

0

5000

10000

15000

20000

25000

30000

35000

Formation

Water

Injection Water Low Salinity

Water

m g / l

Water salinity

TDS

0

200

400

600

800

1000

1200

1400

Formation

Water

Injection Water Low Salinity

Water

m g / l

Divalent Cations

Ca++

Mg++

Example: reduction in salinity

and main divalent cationconcentrationAFES November 2011 - Aberdeen



History, breakthrough

1967: Bernard» “Effects of Floodwater Salinity on Recovery of Oil

from Cores containing Clays”

1995: Morrow, investigative work 2004: first SWCTT; 2008: first inter-well (BP,

SPE129692) 2005: LoSal™ trademark filed by BP

» IP rights on “brand” reflects commercial focus

2011: North Sea» Clair Ridge, Statoil work (Heidrun, Snorre)

+ many more, involuntary, secondary mode, trials…




Wettability changes cause the EOR

effect

Consensus

» The effect is genuinelyattributed to thereduction in salinitycompared to formationwater

» Low Salinity waterinduces a change of rock affinity towardswater (more water-wet)

» Published, convergingevidences, e.g. ShellSPE129564

Implications

» The more oil-wetinitially, the better

» Is it why it works betterin secondary mode ?


1.0000, 0.00001.0000, 0.00000.0000

0.1000

0.2000

0.3000

0.4000

0.5000

0.6000

0.7000

0.8000

0.9000

1.0000

0.0000 0.2000 0.4000 0.6000 0.8000 1.0000

R e l a t i v e P e

r m e a b i l i t y

Water Saturation

Improved fractional flow towards more water-wet

Kro Oil Wet tending

Krw Oil Wet tending

Kro Water Wet tending

Krw Water Wet tending



…though, underlying mechanisms

yet unresolved

Multiple Ion Exchangemechanism (BP)» Lager, 2006» Reduction in divalent

cation break theequilibrium of Electrical Double

Layer, releasingadsorbed oil

Acid/Base reactions

» Tor Austad, Univ. of Stavenger 2010

» In acidic conditions,Ca++ desorbs, A/Breactions release

adsorbed oil

Others» Boussour, Total & Univ. of Bordeaux,

2009: “…counter examples for mostof proposed mechanisms”

» Historically: fines migration, pH» Current research focuses on clays

adsorption, EDL evidence,…» Nearly ALL agree that EOR originates

from change in surface properties of clays (original oil produced fromchange in wettability)




Published field evidence

BP» Endicott (Alaska)» Core tests, Single-Well Chemical Tracer tests (SWCTT),

first inter-well pilot» Excellent agreement between core results and field

results

Shell» Changes of wettability on the field of Omar in Syria,following the injection of ground-water

Statoil» Snorre: good agreement between core tests and

SWCTT, though… negative» Recent press-releases on potential tests ongoing on the

Heidrun field




0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

0.180

0.200

0 0.2 0.4 0.6 0.8 1 1.2

I n c r e m e n t a l R e c e o v e

r y ( F r a c O O I P )

Water salinity (1=Formation Water)

From SPE 93903, mod. L.S

Core Flood

SWCTT

So simple…

(on a system that works)


Apparenttrigger is:divalent

cation lessthan FW



Factors controlling the “Low

Salinity” effect

A set of favourableconditions

» ROCK/RESERVOIR

Presence of clays inmatrix

Some better than others

Tending “Oil wet” High Sor (in situ)

» OIL

Heavy, polar components

» WATER

Salinity less than FW

Less divalent cation

No definite deterministicfactors yet identified

“Screening” helps

Simulation on standardblack oil

Core experiment necessaryto conclude






North Sea or Offshore specifics

Cost of field trials “pilot” phase

Facilities» Footprint, weight of RO and water equipment

» Logistics, planning

» Cost

Environmental

» Saline water discharge probably the only

negative




Technical evaluation of Low

Salinity potential

Integrated project

Sub-surface intensive

Formation Evaluation & Core Analysis playmain role


Screening Feasibility Pilot

a.k.a. … Pre-feasibility, Appraise Concept-Selection of pilot

phase

Phase 1

Implementation

Scope "Score": Reservoir, Oil,Brine. Litterature review

Corefloods, reservoirsimulation, facilities and

development engineering,

logistics, supply chain

Prove in-situ effect,calibrate models

Drivers Screen "wide", Integration Quality, protocols, expertise,

think economics of full project,

Inte rated Team

Acquire data for final

design

Synergies Formation damage, scalemanagement

Surfactants/P, desulfatation,low salinity as a commodity, …



Low Salinity vs EOR alternatives

Clean Low cost

Synergies with ASP, Polymers

Gas injection,

MGI, WAG,

Segregated

CO2 ASP Polymers

A priori uncertainties

Applicability

Evaluation cost

EOR effect

Logistics / Supply

Capex / facilities

Capex / wellsOpex

Safety / Environment

Synergies ? YES YES

Low Salinity's

Advantage

Neutral

Handicap




North Sea Outlook

Inventory of North Sea potential ?

» Narrow base of field candidates» Technical intelligence

» Projects funding ?

Incentives, make EOR competitive» Longer pay-back times compared to “conventional”

projects

» Yet clean and sustainable technique

» Existing schemes vs further tax breaks ?

Freshwater as a commodity» Ageing facilities, footprint, power requirement…




Conclusion

Low Salinity water injection is a specific EOR method» Efficient for a set of reservoir “settings” and fluid “conditions”

» Not yet a deterministic science, but continuously improving Commercial feasibility through experimental programme

» High-tech, integrated, multi-discipline» “Supply” of competences exist» A priori chances of success not yet in “comfort zone”

Everyone likes Low Salinity (…if or when it works)» Environmentally friendly» Low operating costs» Synergies: Surfactants, Polymers, De-sulfatation

Focus areas for a North Sea take-off » 1- Map subsurface potential» 2- Incentives» 3- Facilities…(in this order)




Thank you To the “Low Salinity” scientific community

for their efforts in publishing and sharing

information, allowing us to envisagecommercial applications at earliest

To the AFES for giving us the opportunityto present on this interesting andpromising technique

Oilgen Ltd48 Queens Road AberdeenAB15 4YE

T: +44 1224 327047E: [email protected]: www.oilgen.com

Oilgen on Low Salinity AFES 9 Nov 2011

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