MEOR: From an Experiment to a Model

Sidsel Marie Nielsen, Amalia Halim, Igor Nesterov, Anna Eliasson Lantz, Alexander Shapiro

Stavanger, 18 Nov 2014

RECOVERY MECHANISMS

Reduction of oil-water interfacial tension (IFT) by surfactant production and bacteria.

Fluid diversion by microbial plugging.

Reduction of oil viscosity.

Gas production.

2

3

EXPERIMENTS

4

CHALK ROCKNorth Sea Reservoirs are mainly chalk reservoirs

Chalk rock: Small pore throats, comparable to microbe sizes

Stevns Klint outcrop: Model study, pore throat size: 0.004-6.1µm

Bacterial sizes: 0.5x3µm

Scanning Electron Microscope of Cretaceous, Maastrictian M1b1 unit reservoir chalk (Maersk Oil, 2014)

SPORE PROPERTIESModel bacteria used in penetration test:Bacillus licheniformis 421 (spore-forming)Pseudomonas putida K12

Vegetative cellGrowing with metabolism.

SporeSporulation induced by stress.Dormant (non-growing).Smaller size.Different surface properties.Reactivation.

5

http://bio1151.nicerweb.com/Locked/media/ch27/endospore.html

6

Schematic Core Flooding Set-upInjection cylinder 1 = brine/nutrient 2 = bacteria3 = crude oil

Pressure tapped core holder

Fridge

P1 P2 P3

Fraction collector

dPi = differential pressure transducer = pressure tapped (0.5”, 1.5”, 2.5”) = thermocouple = valves = safety valves

Temperature controller

ISCO pump(injection)

dPi

ISCO pump(Sleeve pressure)

Heating jacket

1 2 3

Webcam

Methods

7

Spore-forming vs non-spore-formingBacteria penetration study/One phase liquid core flooding: Halim et. al., Transp. Porous Med. (2014) 101, 1–15. doi:10.1007/s11242-013-0227-x

• More cells were found in the effluents of core flooding with B. licheniformis 421 as compared to P. putida K12

• Survival/motion of bacteria can be mainly due to spores.

In 2 3 4 5 6 71E+00

1E+02

1E+04

1E+06

1E+08

1E+10

0123456789

bacteria cell (core 2)bacteria cell (core 10)

PVI

viab

le c

ell (

cfu/

mL)

B. licheniformis 421

In 2 3 4 5 6 7 1 2 3 4 5 6 71E+00

1E+02

1E+04

1E+06

1E+08

1E+10

0123456789

bacteria cell (core 5)bacteria cell (core 9)

PVI

viab

le c

ell (

cfu/

mL)

pH

P. putida K12

8

Penetrated bacteriaBacteria penetration study/One phase liquid core flooding: Halim et. al., Transp. Porous Med. (2014) 101, 1–15. doi:10.1007/s11242-013-0227-x

B. licheniformis 421 cells under DAPI staining (a) in growth media, before injection into a chalk core plug, cell size 0.5 x 3µm (b) in the effluent from a chalk core plug, spore formation

spore

ba

9

Flooding sequences

1. Injection of SS (2-3 PVI)2. Injection of crude oil until Swi

3. Injection of 1PV SS (1st SS)4. Injection of bacteria (1PV)5. Incubation (3 days)6. Injection of SS until Sor (2nd SS)7. Injection of nutrient (1PV)8. Incubation (7 days)9. Injection of SS (3rd SS)

Secondary

1. Injection of SS (2-3 PVI)2. Injection of crude oil until Swi

3. Injection of SS until Sor (1st SS)4. Injection of bacteria (1-3PV)5. Incubation (3 days)6. Injection of SS (2nd SS)

Tertiary

“Tertiary recovery” “Secondary recovery”

10

Core plug properties

Core ID

k before (mD)

k after (mD)

before

(%)

after (%)

26_water 3.2 2.8 30.8 30.726_3rd m 3.2 3.1 31.1 30.7

26_2nd m 3.1 3.2 30.7 30.8

• Core 26 – homogenous reservoir chalk core

• No significant change in k and before and after experiment

• No fractures based on CT scan results before and after experiments

11

Results

Tertiary oil recovery method with production stopped at 11.5 PVI.1 PV bacteria injected and incubated.Additional oil: 2.3 % OOIP.

Core no Sor (% OOIP)

26_water 45.226_3rd method 44.2

Samples Viscosity (cP)

Crude oil 4.96SS 0.55

SS+molasses+bacteria 0.55

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

core 26_water_1st SScore 26_water_2nd SScore 26_3rd method_1st SScore 26_3rd method_bacteriacore 26_3rd method_2nd SS

PVI

cum

mul

ative

oil

prod

uctio

n (%

OO

IP)

1.4 %55.8% 0.9 %

Do bacteria produce more oil?

12

Results

Secondary oil recovery method produces 3.3 % OOIP compared to tertiary method. 1 PV bacteria injected 1 PV after break-through.

Core no Sor-1PV (%)26_2nd

method 56.7

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

core 26_water_1st SScore 26_water_2nd SScore 26_3rd method_1st SScore 26_3rd method_bacteriacore 26_3rd method_2nd SScore 26_2nd method_1st SScore 26_2nd method_bacteriacore 26_2nd method_2nd SScore 26_2nd method_nutrientcore 26_2nd method_3rd SS

PVI

cum

mul

ative

oil

prod

uctio

n (%

OO

IP)

vs. 2nd method 3.3 % (at 18.3 PVI)

Secondary vs tertiary recovery?

Total oil recoveryWater : 54.8%Bacteria_3rd : 58.1%Bacteria_2nd : 61.6%

13

SIMULATIONS

1D MEOR SIMULATOR Generic model. Growth and other reactions. Bacterial surfactant reducing IFT. Bacteria attachment due to

filtration or equilibrium adsorption.

Plugging Application of spore-

forming bacteria.

SIMULATOR OVERVIEW

14

www.123rf.com

1D MEOR MODEL

1 1

p pn n

ij j j ij j j ij j

s v f qt x

{ , , , , }, { , }i o w b s m j o w

15

ReactionBacteria, surfactant and substrate.

Sporulation

AttachmentIrreversible deep bed filtration.

Pore size vs. bacteria size.

16

( )·

( )s w

b sb bw maxs s w

r Y rK

0att bwr v

00.1sp

spa spwttr v

( )s x xyij bsr K a

bacteria pore substrateb sp sa s aa

SOURCE TERMS

SPORULATION

17

Sporulation Sigmoid-shaped curve

for stress response in bio-systems

Conversion releases substrate.

Reactivation Triggered by good

conditions for survival10-7 10-6 10-5 10-3 10-2 10-1

0.0

0.1

0.2

0.3

0.4

0.5

Con

vers

ion

rate

s

Kbs

Ksb

EFFECTS

Oil mobilization

Surfactant production

IFT reduction

Residual oil saturation

Relative permeability

Fractional flow

Option: Porosity reduction

Attachment

Microbial growth

Porosity reduction

Water relative permeability

Fractional flow

18

PROFILE CHARACTERISTICS

19

0.0 0.2 0.4 0.6 0.8 1.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

satu

ratio

n

sw (0.21 PVI) sor (0.21 PVI) sw (0.30 PVI) sor (0.30 PVI)

Two oil banks appear.

Injection Constant rate.Continuous.

Oil bank

RISK OF INLET CLOGGING

Two bacteria peaks.

Surfactant effect.

Inlet clogging risk.

Increased recovery.

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0.0 0.2 0.4 0.6 0.8 1.00.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

7.0x10-4

Vol

ume

frac

tion

Bac attached Bac water Metabolite water

0.32 PVI

0.0 0.2 0.4 0.6 0.8 1.00.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

7.0x10-40.48 PVI

Vol

ume

frac

tion

Bac attached Bac water Metabolite water

SLUG INJECTION SCHEME

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0.0 0.2 0.4 0.6 0.8 1.00.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

7.0x10-40.48 PVI

Vol

ume

frac

tion

Bac attached Bac water Metabolite water

subs

trat

e +

spor

es

subs

trat

e

wat

er s

lug

t1 t2

Slug injection scheme selected to avoid clogging and to concentrate attached bacteria in specific zones in the reservoir.

0.0 0.5 1.00.0

2.0x10-6

4.0x10-6

6.0x10-6

8.0x10-6

1.0x10-5

1.2x10-5

1.4x10-5

Vol

umet

ric c

once

ntra

tion

Bacteria att Bacteria water Substrate Metabolite water Spores water Spores att

0.67 PVI

0.0 0.5 1.00.0

5.0x10-5

1.0x10-4

1.5x10-4

2.0x10-4

2.5x10-4

3.0x10-4

3.5x10-4

4.0x10-4

0.82 PVI

Vol

umet

ric c

once

ntra

tion

Bacteria att Bacteria water Substrate Metabolite water Spores water Spores att

0.0 0.5 1.00.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

7.0x10-4

8.0x10-4

0.86 PVI

Vol

umet

ric c

once

ntra

tion

Bacteria att Bacteria water Substrate Metabolite water Spores water Spores att

0.0 0.5 1.00.0

1.0x10-4

2.0x10-4

3.0x10-4

4.0x10-4

5.0x10-4

6.0x10-4

7.0x10-4

8.0x10-4

9.0x10-4

0.94 PVI

Vol

umet

ric c

once

ntra

tion

Bacteria att Bacteria water Substrate Metabolite water Spores water Spores att

RELEASING PROCESS

22

Water slug induces conversion of attached bacteria to spores.

Rate of conversion is determined by released substrate and thus bacteria concentration.

REDUCTION OF CONVERSION RATE

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0.0 0.2 0.4 0.6 0.8 1.00.0

5.0x10-5

1.0x10-4

1.5x10-4

Volu

me fra

ctio

n

Bacteria att 0.6 Substrate 0.6 Bacteria att 0.5 Substrate 0.5 Bacteria att 0.4 Substrate 0.4

Waterslug

Waterslug

Waterslug

0.0 0.5 1.0 1.5 2.00.0

0.2

0.4

0.6

0.8

Rec

over

y

(PVI)

1e-3 2e-3 3e-3 4e-3 5e-3

Substrate concentrationSubstrate slug 0.07 PVI

Water slug 0.13 PVI

SUBSTRATE AND SLUGS

24

HIGH SUBSTRATE INJEC- TION CONCENTRATIONFaster MEOR responseSpore injection and spore-forming bacteria injection are similar

Waterflooding curve corresponds to 1e-3 curve.

SPORE-FORMING BACTERIA

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SLUGS Reduced clogging risk Larger surfactant

production Improved utilization

of substrate Prolonged oil

mobilization

0.0 0.2 0.4 0.6 0.8 1.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Sat

urat

ion

sw NSP slug 0.20 sw SP slug 0.20 sor NSP slug 0.20 sor SP slug 0.20

second water front

SLUG INJECTION SCHEMES

26

High substrate injection concentration.

First slug is important for final recovery.

Improved utilization of substrate injected.

1.0 1.5 2.0

0.64

0.66

0.68

0.70

0.72

0.74

0.76

RF

(O

OIP

)

(PVI)

1 x slug 0.15 1 x slug 0.20 2 x slug 0.12 wslug 0.30 5 x slug 0.07 wslug 0.30 5 x slug 0.07 wslug 0.20 1 x slug 0.20 NSP 0.20 sub, 0.95 water, 0.06 sub 0.20 sub, 0.85 water, 0.06 sub

CONCLUSION

Spore-forming bacteria penetrate tight chalk better and may be used for MEOR.

Experimental discoveries lead to new MEOR features to investigate numerically:

Filtration type behavior (no biofilms)

Spore formation

Selective plugging

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CONCLUSION Numerical simulations show that spore-forming bacteria have

the potential to avoid clogging due to sporulation.

High substrate injection concentration gives fast MEOR response.

Prolonged oil mobilization with water slugs due to substrate release from sporulation of attached bacteria.

It is possible to optimize the recovery by selecting right slug sizes and sequences

It is possible to deliver spores to a certain point at the reservoir and make them plugging there.

The first slug is the most important for final recovery.

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QUESTIONS?Thank you for your attention.

29

30

31

Measurement of k and , CT scan

Core Flooding Experimental Flow Chart

Core plug saturation under vacuum and high pressure

Methods

Core plug: Cleaning

Measurement of oil produced

Effluent

Bacterial counting

32

Methods

1. Injection of SS (2-3 PVI)2. Injection of crude oil until Swi

3. Injection of 1PV SS (1st SS)4. Injection of bacteria (1PV)5. Incubation (3 days)6. Injection of SS until Sor (2nd SS)7. Injection of nutrient (1PV)8. Incubation (7 days)9. Injection of SS (3rd SS)

Secondary

1. Injection of SS (2-3 PVI)2. Injection of crude oil until Swi

3. Injection of SS until Sor (1st SS)4. Injection of bacteria (1-3PV)5. Incubation (3 days)6. Injection of SS (2nd SS)

Tertiary

Different studies:

1. Injection of SS (2-3 PVI)2. Injection of crude oil until Swi

3. Aging – 3 weeks4. Injection of crude oil (2-3 PVI)5. Injection of SS until Sor (1st SS)6. Injection of bacteria (1-3PV)7. Incubation (3 days)8. Injection of SS (2nd SS)

Wett

abillity

33

Methods

Effluent (oil in brine)

Add 3ml toluene

Hand shake to dissolve the oil

Let the oil in toluene and brine seperate into two phases

Upper phase (oil in toluene) was decanted to a silica glass cuvette

Measure at UV-vis spectrophotometer at λ=750 nm

Oil Measurement ( Evdokimov et. al., 2002)

34

Results

• The UV/visible spectroscopy method relies on absorptivities of solid asphaltene aggregation in toluene solution.

• Fig. a shows good linear regression of the NO concentration vs. the absorbance data. The replicate samples showed similar linear regression trend line which means this method is quite stable and reproducible.

• This method can detect oil as low as 1 µl (Fig. b).

0 0.05 0.1 0.15 0.2 0.250

0.2

0.4

0.6

0.8

1

f(x) = 4.1227426046552 x + 0.0111858430033472R² = 0.997046095524364

200-1 µl fitLinear (200-1 µl fit)

oil (ml)

Opti

cal D

ensi

ty (7

50 n

m)

0

0.5

1

1.5

2

2.5

3

3.5NOLinear (NO)

oil (ml)

Ab

sorb

an

ce (

λ =

75

0n

m)

UV-vis methoda) b)

35

Results

Core ID

k before (mD)

k after (mD)

Before

(%)

after (%)

26_water 3.2 2.8 30.8 30.726_3rd m 3.2 3.1 31.1 30.7

26_2nd m 3.1 3.2 30.7 30.8

26_aging 2.8 3.1 30.7 30.6

• Core 26 – homogenous reservoir chalk core• No significant change in k and before and after

experiment• No fractures based on CT scan results before and after

experiment

Core Plugs Properties

36

Results

• Experiment with an aged core gave 3.6% incremental oil, very slightly higher than non-aged core

Core no Sor (% OOIP)26_aging 48.6

Wettability alteration?

Total oil recovery: Aged core : 55.6%

0 3 6 9 12 15 18 21 24 27 30 330

20

40

60

80

100

core 26_water_1st SScore 26_water_2nd SScore 26_3rd method_1st SScore 26_3rd method_bacteriacore 26_3rd method_2nd SScore 26_aging_1st SScore 26_aging_bacteriacore 26_aging_2nd SS

PVI

cum

mul

ative

oil

prod

uctio

n (%

OO

IP)

0.4 % 3.2 %52.0%

NUMERICAL SOLUTION

Tanks-in-series approachMultivariable Newton iterationSequential procedure

37