mM H2S, NO3-

Oil related microbiology Oil related microbiology

Terje Torsvik

UNI - CIPR

CENTRE FOR INTEGRATED PETROLEUM RESEARCH

Important microbial processes in oil production:

Reservoir souring Reservoir souring

Microbial Influenced Corrosion (MIC) Produced water reinjection (PWRI) Microbial Enhanced Oil Recovery

VFB

VFA

Reservoir souring in offshore oil production Reservoir souring in offshore oil production

Sea water is injected into the reservoir as Sea water is injected into the reservoir as

pressure support

Oxygen is removed to reduce corrosion Sea water contains 28 mM sulphatep

Sea water injection promotes growth of SRB in the water injection system and in the

reservoir

SRB use sulphate for respiration

:

SO

H S SO

→ H

S

H S bl b it i t i d i

H²S cause problems because it is toxic and corrosive Traditionally biocides have been used to inhibit SRB

An alternative method based on nitrate injection have been developed in collaboration with Statoil and Hydro

in collaboration with Statoil and Hydro

Microbial production of H

S in the oil reservoir Microbial production of H

S in the oil reservoir

•H

S production increases dramatically over the

lifetime of a production well.

•High H

S levels may lt i h t d f th result in shut down of the well and reduced oil and gas production.

•H

S is toxic and corrosive

Ref. : Sunde et al. (1993). Field related mathematical

• Strong restrictions on H

S concentration in

export gas

export gas

Laboratory experiments:

Effect of nitrate injection on H ² S production

Sulphide production and nitrate injectin in column.

1,2 1,4

mM H2S mM NO3

0,4 0,6 0,8 1,0

mM H2S, NO3-

0,0 0,2

100 300 500 700 900 1100

Time (days)

Ref : Myhr et al (2002) Inhibition of microbial H2S production in an oil reservoir Ref.: Myhr et al. (2002). Inhibition of microbial H2S production in an oil reservoir model column. Appl. Microbiol Biotechnol 58: 400-408.

Monitoring SRB in the field:

Gullfaks Water injection system

Monitoring SRB in the field:

Biofilm sampling

Sampling point

Sampling point

Biocoupons collected from pipiline Biocoupons collected from pipiline Placed in box for anaerobic transportation Filled up with anaerobic injection sea water

Metal coupons incubated in pipeline

Measuring microbial activity in the water injection system

The biofilm is analyzed for microbial activity

GAB SRB NRB

Water injection system at Gullfaks.

Bacteria in biofilm before and after nitrate treatment Bacteria in biofilm before and after nitrate treatment

1,0E+09 1,0E+10

1 0E 06 1,0E+07 1,0E+08 1,0E 09

m2

1,0E+04 1,0E+05 1,0E+06

Log cells/cm

1,0E+01 1,0E+02 1,0E+03

1,0E+00 ,

feb.89 jun.90 dec.91 mar.93 apr.94 nov.94 jul.95 jun.96 feb.97 mar.98 may.99 feb.00 aug.00 may.01 mar.02 feb.03

Time (months)

SRB FA

Biocide (glutaraldehyde) Nitrate (start oct. 99)

SRB-FA SRB-MPN NRB

Total bacteria

Detection limit FA method: 1e+05 cells/cm2 Detection limit MPN method: 6 cells/cm2

SRB activity and corrosion rate at GFB

ay)

Nitrate added

year)

1,0 1,2

H2S/cm2 /da

20 25

rate (mm/y

0,6 0,8

n rate (µg H

15

Corrosion 0,2 0,4

e respiration

5 10

r.94 p.94 v.94 r.95 ul.95 ct.95 r.96 n.96 p.96 c.96 b.97 r.97 y.97 g.97 v.97 n.98 b.98 r.98 y.98 p.98 s.98 y.99 g.99 v.99 b.00 n.00 g.00 v.00 s.00 b.01 y.01 g.01 v.01 r.02 ul.02 ct.02 b.03 n.03

0,0

Sulphate

0

Time (month)

ap sep nov ma ju oc ma jun sep dec feb ma may aug nov jan feb ma may sep des may aug nov feb jun aug nov des feb may aug nov ma ju oc feb jun

Corrosion rate SRBactivity SRB activity

H2S in produced water on Gullfaks C H2S in produced water on Gullfaks C

9 10

6 7 8

e water

3 4 5

mg H2S/litre

measured mg H2S in water Theoretical H2S development

0 1 2

m 3

Start of nitrate injection

0

nov-97 sep-98 jul-99 mai-00 feb-01 des-01 okt-02 aug-03

Date

Sunde, Egil; Lillebø, Bente-Lise Polden; Bødtker, Gunhild; Torsvik, Terje; Thorstenson, Tore. H2S inhibition by nitrate injection on the Gullfaks field.NACE Corrosion 2004, Paper No 04760; 2004

Produced Water Reinjection (PWRI) Produced Water Reinjection (PWRI)

Produced Water Reinjection (PWRI) has been used on platforms, mainly due to requirements from the Norwegian Pollution Agency regulating release of hydrocarbons to the sea.

regulating release of hydrocarbons to the sea.

In the event of permission to produce oil in the Barents Sea, there must be zero release of hydrocarbons to the environment.y

Challenges:

High temperature stimulate growth of thermophilic SRB

Increased supply of VFA in the injected water stimulate reservoir souring

PWRI at Statfjord PWRI at Statfjord

Injection water:

Cold sea water (StA) Hot produced water (StC)

Microboal analysis of back flooded injection water

Ocean floor

Injection well Production well

Injection water Injection water

St A and B: Sea water St C: Produced water

Oil reservoir

St C: Produced water

Samples p

• Back-flooded injection water from wells 3000 meters below sea floor.

• From each injector: 9 samples taken at different times (0 – 96 hours)

• From each injector: 9 samples taken at different times (0 – 96 hours) of back-flooding.

Sample Statfjord A Statfjord B Statfjord C

Injected with Sea water Sea water Produced water

Temperature 30 °C 30 °C 60 °C

Temperature 30 C 30 C 60 C

Treatment Deoxygenated,

biocide treatment

Deoxygenated, nitrate treatment

Deoxygenated,

75 % produced water 75 % produced water 25 % seawater

Souring potential H₂S mg/liter

(calculated by Statoil)

30 <1 200-400

epsilon

Principal component analysis of native populations at St A and C

Statfjord A (StA) Statfjord C (StC) Produced water (PW)

1.0

epsilon

Archaeog Thermoc

StC

Actinob Deferrib

Archaeog

Backflow delta

StA

beta Firmic

PW

-0 6 1 2

-1.0

alpha

0.6 1.2

K. Lysnes, G. Bødtker, T. Torsvik, E. Ø. Bjørnestad & Egil Sunde:

Appl Microbiol Biotechnol (2009) 83:1143–1157

MEOR

Principles – reservoir effects

BACTERIA + OIL + N + P + O

DU CED

CIAL ON

RE DU

CE WAT PE REDU

INTERFACIA TEN

SION CE

D ATER PERME

ABI LITY

MOBILISED RESIDUAL OIL ENHANCED SWEEP EFFICIENCY

Y

MOBILISED RESIDUAL OIL ENHANCED SWEEP EFFICIENCY

Microbial biofilm on oil

crude oil

Bacterial colony surrounded by water

IFT laser light scattering IFT laser-light scattering

• Best suited for low values (< 30 mN/m)

• Measurement range is 10

– 10

mN/m

• Method has been successfully applied down to 10

mN/m

Bacterum: Dietsia maris

D d k bi th ti t

100

OW IFT

Dodekan, aerobic synthetic sea water

10

OW IFT OWB IFT 4.0 ml/h 0.9 ml/h 1.8 ml/h

0,1 1

IFT (mN/m) ^{1.8 ml/h}

2.7 ml/h 5.4 ml/h

0,01

0,001

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Run time (days)

Kowalewski, E., Rueslåtten, I., Gilje, E., Sunde, E., Bødtker, G., Lillebø, B.L.P., Torsvik, T., Stensen, J.Å., Bjørkvik, B.

and Strand K A 2005 "Interpretation of Microbial Oil Recovery from Laboratory Experiments" Paper presented at the and Strand, K.A., 2005, Interpretation of Microbial Oil Recovery from Laboratory Experiments , Paper presented at the 13th European Symposium on Improved Oil Recovery, Budapest, Hungary, Apr 25-27

Hopeman sandstone core

L b t i t

Statfjord model oil

Fl t 0 1 l/ i 1 PV/d

Laboratory experiments

Flow rate: 0,1 ml/min = 1 PV/d

Anoxic synthetic Sor0,38 Anoxic synthetic

seawater

Microbes, O2, N, P 0,36

, , ,

0,34

0,32

0 5 10 15 20

Time (days)

MEOR at Norne

Injection of aerobic seawater from start in 1997

1997

MEOR implemented in January 2001 by

adding N and P to the injection water to

adding N and P to the injection water to

stimulate bacterial growth in the reservoir

Nitrate is also added in order to inhibit

reservoir souring

MEOR at Norne MEOR at Norne

2002: Increased oil production from MEOR at Norne – 900 000 m

– 1 % of producible oil p

– At an oil price 20 $ per barrel and 1$= 5 NOK this amounts to approximately 750 000 000 NOK. pp y

(Reported from Norne to OD in 2002)

( p )