33rd IEAEOR Syypmposium

3333rdrd IEAEOR SymposiumIEAEOR Symposiumy py pA u g u s t 2 6 ‐ 3 0 , 2 0 1 2

Presenter’s Name Paper Title & Session Date

Author’s Name

G. Renard ‐ IFPEN Advanced screening technologies for the selection of dense CO2

foaming surfactantsAuthor s Name foaming surfactants

Session 2: Theme BM. Chabert – RhodiaM Morvan – Rhodia

Monday August 27thM. Morvan RhodiaL. Nabzar – IFPEN

APPLICATION BACKGROUND: DENSE CO2 EOR in USA

• 5 % of USA domestic oil is produced by CO2 flooding• Water alternating gas (WAG) injection is often used: better sweep• CO is a dense solvent in USA reservoirs conditions: untrapping• CO2 is a dense solvent in USA reservoirs conditions: untrapping

efficiency• Only about 20 % OOIP is recovered with present techniques

• A better mobility control could improve recovery by several %• A better mobility control could improve recovery by several %• For that purpose, today only CO2 foams are economically realistic

• Foam Assisted WAG (FAWAG)Dedicated surfactants are needed for dense CO foams (emulsions)• Dedicated surfactants are needed for dense CO2 foams (emulsions)

• We studied water soluble surfactants: easier application in a WAG context

Water / CO2

OilWater + Surfactant / CO2

OilWAG FAWAG

33rd IEA EOR Symposium – Regina – August 26‐30, 2012

OUTLINE

Development of specific high pressure screening tools

Petrophysics application tests on designed products


SCREENING WORKFLOW

• Challenges:• All screening must be done under pressure• Current methods not high throughput (high pressure foam stability)• Current methods not high throughput (high pressure foam stability)

• Surfactant interfacial action with dense CO2 is a pre-requisite for foam formation and stabilization:

• Interfacial tensions (IFT) in the 1 mN/m range needed• A high pressure IFT screening system patented • Used prior to more classical tests

Number of formulations Tests

10

>100

10

>100 IFT measurements

Foam stability under high pressure


22 Petrophysics

IFT MEASUREMENTS: JET/DROP TRANSITIONWe use a patented higher throughput method based on jet-drop transition phenomenon:

• Co-axial flow of two immiscible liquids in microfluidic geometries• Co-axial flow of two immiscible liquids in microfluidic geometries• Depending on applied flow rates, either drops or jet can form

Drop / jet transitionSystem geometry 200 µm

Q externalQ internal

p j

JETTransition parameters:

Q externa

l

DROPS Jet/drop/jet transition

• Viscosities

• Capillaries radii

• Interfacial tension (IFT)

Q internal

Q

Guillot et al. PRL 2007

Interfacial tension (IFT)


The jet/drop transition in the flow rates plane depends strongly on IFT

HIGH PRESSURE JET/DROP TRANSITION

• The jet/drop transition technique was adapted to high pressure using silica capillaries (up to 250 bars, 80 ºC)

• Measuring the shift in the jet-drop transition line allows measuring IFTMeasuring the shift in the jet drop transition line allows measuring IFT and comparing products for interfacial effect with dense CO2

Jet/drop transition Typical jet/drop transition Dependence of the pphenomenon in silica

capillaries, up to 200 bars

yp j pdiagram in the CO2/water

flow rates plane

ptransition line location on IFT

CO2 drops in aqueous solution Region of convected

CO2 jet in aqueous solutionDROPS

JET

IFT decrease

Flow direction Region of absolute instability

instability

Marre et al. APL 2009

200 µm

DROPS


Allows estimation of aqueous surfactant solution/dense scCO2 IFT1 sample/hour

RESULTS OF HIGH PRESSURE IFT TESTS

Brine( reference) Alfa olefin sulfonate

SurfactantdC40

Betaineγ=20 mN/m

Antarox L62 Brine transition reference

IFT↓ Surfactant transition

γ=2 mN/m

• Jet/drop screening 25oC, 90 bars (dCO2=0.75)

• Product comparison by observation of shift in transition line.

• Alfa olefin sulfonate and betaine only have limited interfacial action with dense CO2 (although they are good foamers with e.g. N2)


2 ( g y g g 2)• New surfactant dC40 has good interfacial activity, comparable to the

Antarox L62 (= Pluronic L62) benchmark

SECOND SCREENING STEP: HIGH PRESSURE FOAM STABILITY

• Foam is generated using a highAutoclaveHigh pressuregas and liquid Foam is generated using a high

pressure autoclave:Fast & reproducible foam generationMi i f t t b

Out

pumps

CO2 / water foamBackpressure

regulator25°C<T<150°C

0<P<150 bars • Microscopic foam structure can be observed at autoclave outlet in a transparent silica capillary

High pressureview cell

Camera0<P<150 bars

• Foam is then transferred in a high pressure variable volume view cell

• Foam height is measured as a

50 µm

Foam height is measured as a function of time in high pressure conditions

Photograph of the high pressure view

cell

Observation of foam in capillary

at outlet of


cell autoclave

RESULTS FOR HIGH PRESSURE FOAM STABILITY

dC40 surfactant formulation CO2 foamA l i

1 cm

Foam stabilityas a function of time in 0,9

1

to 3 h 12 h 24 h

Antarox benchmark

e (%

)

dC40

Aqueous solution

high pressure view cell

After drainage

40oC 130 bars0 20,30,40,50,60,70,8

to 3 h 12 h

Alfa olefin sulfonate (AOS) benchmark

tive

foam

volu

me

Antarox

AOS 40oC, 130 bars 40 g/L Na2CO30

0,10,2

0 20 40 60to 3 h 12 hR

elat

Time (hours)

AOS

• Foam stability over 24 hours are obtained using the new dC40 surfactant family

• This over performs literature benchmarks, e.g. alfa olefin sulfonates


and Antarox

PRODUCT DESIGN RULES

• Based on literature, good interfacial activity is provided by:• Branching of the hydrophobe• Addition of ethoxylates

• Our measurements suggest that additional activity is obtained by:obtained by:

• Replacement of ethoxylates by propoxylates • Use of twin-tailed molecules/gemini type surfactant

The dC40 industrial surfactant family was designed toThe dC40 industrial surfactant family was designed to incorporate those features in addition to long term chemical stability and limited adsorption


y

OUTLINE

Development of specific high pressure screening tools

Petrophysics application tests on designed products


PETROPHYSICS EXPERIMENTAL CONDITIONS

• Low permeability 10 mD Indiana limestone cores, 30 cm• Temperature 40oC, 130 bars pressure: dense supercritical CO2 (d=0.7).• Vertical co-injection from top of the core & foam in-situ visualizationVertical co injection from top of the core & foam in situ visualization• 40 g/L Na2CO3 injection brine is used to inhibit carbonate dissolution

Effect of CO2+ NaCl brine injectionSchematic of CO2 coreflood setup Effect of CO2+ NaCl brine injection on Indiana limestone core

BACK PRESSURE130 bars

LIQUID PUMP

PT's : HP TRANSDUCERS

WASTE

Schematic of CO2 coreflood setup

Rock dissolution

Na2CO3Solution (40g/l)

TRAN

SDU

C0-20 bar

He HeHeHe

Surfactant in Na2CO3Solution

PT1

HP VISUAL CELL

GAS FLOW METER

WASTE

Core face after co‐injection of

CO2/NaCl brine

Original core face prior to

CO2/NaCl brine

Rock dissolutionCER

rs

CO

2C

O2

PT2

CORE HOLDER

LIQUID-GAS SEPARATOR


2(130 bars, 40 oC)

2co‐injection

Hewater

HeHewater

OVEN, T=40°C

CO2 PUMP

BASICS OF DENSE CO2 FOAMS IN POROUS MEDIA

• Resistance factor defined as Rf=∆P(foam)/∆P(water+CO2) • Foam quality is the gas fraction, i.e. the ratio of gas flow rate

t th fl t f t +to the flow rate of water+gas:• Existence of two foam regimes depending on foam quality• Maximum pressure drop at a fixed flow rate obtained at critical

fractional flow Fg*• Existence of a minimum velocity/pressure gradient for foam

generation N2 foam Rfgeneration • Dense CO2 foams have

particularities:Lo minim m elocit

CO2 foam Rf

• Low minimum velocity for foam generation

• Low mobility reduction vs. N2

CO2 foamgeneration

N2 foam generation


• Only few literature on ourparticular conditions

Adapted from Gauglitz&Rossen, Chem. Eng. Science 57, 4037 (2002)

FOAM GENERATION USING DC40 FORMULATION

• Core initially pre-saturated with dC40 surfactant solutionMonophasic dynamic adsorption < 0.2 mg/g

• Foam generated above 15 µm/s (24 cc/hr) interstitial velocities• Foam generated above 15 µm/s (24 cc/hr) interstitial velocitiesConsistent with literature (Gauglitz and Rossen 2002)

• Stable pressure gradient set-up within two pore volume of CO2/aqueous solution co-injection (80 % foam quality)

Visualization of fluids at core outlet (130 bars)

Pressure signal during CO2/formulation co‐injection at 48 cc/hr, 80 % quality

0 3

0,4

0,5

P (M

Pa)

a)

core outlet (130 bars)injection at 48 cc/hr, 80 % quality

0,1

0,2

0,3

Pres

sure

Dro

p


00 2 4 6 8 10 12

PV

During water/CO2co‐injection

During formulation /CO2 co‐injection

OPTIMAL FOAM QUALITY AND MOBILITY REDUCTION

Determination of optimal foam quality Resistance factor and pressure drops as a function of flow rate and fractional flow

0,50

Pa)

1 9

2 8,5Pressure Gradient Resistance Factor @ fCO2=0,8m

)

0 30

0,35

0,40

0,45

e D

rop

P (M

Pa)

re D

rop

(MP

1 5

1,6

1,7

1,8

1,9

dien

t (M

Pa/m

)

7

7,5

8

ce F

acto

r

fCO2=0,8Q=36ml/h

f =0 8 nce

fact

or

dien

t (M

Pa/

m

0,15

0,20

0,25

0,30

Ove

rall

Pres

sure

rall

Pre

ssur

1 1

1,2

1,3

1,4

1,5

Pres

sure

Gra

d

5,5

6

6,5

Res

ista

ncfCO2=0,8 Q=18ml/h

Res

ista

n

essu

re g

rad

0,10

,

0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1Foam Quality fg (fractional flow of sc-CO2)Foam Quality fg (frac. flow of sc-CO2)

Ove 1

1,1

1,5E-05 2,0E-05 2,5E-05 3,0E-05 3,5E-05Intersticial Velocity (Total, m/s)

5

Interstitial velocity (total, m/s)P

re

• Optimal foam quality (scCO2 fraction) is around 0.6This is consistent with low permeability used cores

• Measured resistance factors are in line with the low permeability


• High hysteresis behavior (shear thinning) should permit good injectivity combined with good mobility control

CONCLUSIONS

• A dedicated workflow has been setup to specifically address the case of dense CO2 foams EORI d t i l d t di l i d f ( b• Industrial products displaying good performance (above literature benchmarks) have been identified using a systematic analytical workflow

• These products were characterized in dedicated petrophysics equipments

• Petrophysics measurements are in line with the few literature• Petrophysics measurements are in line with the few literature available on the subject

• Next steps:• Deepen physical understanding of dense CO2 foams behavior in

porous media


porous media• Tune formulations for CO2 solubility

Thank you for your attention


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33rd IEAEOR Syypmposium