Oil related microbiologyOil related microbiology

Terje Torsvik

UNI - CIPR

CENTRE FOR INTEGRATED PETROLEUM RESEARCH

Important microbial processes in oil production:Reservoir souringReservoir souring Microbial Influenced Corrosion (MIC)Produced water reinjection (PWRI)Microbial Enhanced Oil Recovery

VFB

VFA

Reservoir souring in offshore oil productionReservoir souring in offshore oil production

Sea water is injected into the reservoir asSea water is injected into the reservoir as pressure support

Oxygen is removed to reduce corrosionSea water contains 28 mM sulphatepSea water injection promotes growth of SRB in

the water injection system and in the reservoir

SRB use sulphate for respiration:

SO 2 H SSO42- → H2S

H S bl b it i t i d iH2S cause problems because it is toxic and corrosiveTraditionally biocides have been used to inhibit SRB An alternative method based on nitrate injection have been developed in collaboration with Statoil and Hydroin collaboration with Statoil and Hydro

Microbial production of H2S in the oil reservoirMicrobial production of H2S in the oil reservoir

•H2S production increases dramatically over the lifetime of a production well.

•High H2S levels may lt i h t d f thresult in shut down of the

well and reduced oil and gas production.

•H2S is toxic and corrosive

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

• Strong restrictions on H2S concentration in export gas Ref. : Sunde et al. (1993). Field related mathematical

model to predict and reduce reservoir souring. SPE 25197 (1993)

export gas

Laboratory experiments:Effect of nitrate injection on H2S 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

, NO

3-

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 reservoirRef.: 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 pipilineBiocoupons 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 NRBSRB

Water injection system at Gullfaks.Bacteria in biofilm before and after nitrate treatmentBacteria 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.9

4

nov.

94

jul.9

5

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-FASRB-MPNNRBTotal bacteria

Detection limit FA method: 1e+05 cells/cm2Detection limit MPN method: 6 cells/cm2

SRB activity and corrosion rate at GFB

ay)Nitrate added

year

) 1,0

1,2

H2S

/cm

2 /da

20

25

rate

(mm

/y

0,6

0,8

n ra

te (µ

g H

15

Cor

rosi

on

0,2

0,4

e re

spira

tion

5

10

r.94

p.94

v.94 r.95

ul.9

5ct

.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.0

2ct

.02

b.03

n.03

0,0

Sul

phat

e

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 SRBactivitySRB activity

H2S in produced water on Gullfaks CH2S in produced water on Gullfaks C

910

678

e w

ater

345

mg

H2S

/litre

measured mg H2S in waterTheoretical H2S development

0123m

Start of nitrate injection

0nov-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 nitrateinjection 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 StatfjordPWRI at Statfjord

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

Microboal analysis of back flooded injection water

Ocean floor

Injection well Production wellInjection waterInjection water

St A and B: Sea water

St C: Produced waterOil reservoir

St C: Produced water

Samplesp• 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 °CTemperature 30 C 30 C 60 C

Treatment Deoxygenated, biocide treatment

Deoxygenated, nitrate treatment

Deoxygenated, 75 % produced water75 % produced water25 % seawater

Souring potentialH2S 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

ActinobDeferrib

Archaeog

Backflowdelta

StA

betaFirmic

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 + O2

DUCED CIAL ON

REDUCE

WATPE

REDU

INTERFA

CIATE

NSION

CED

ATER

PERMEABILITY

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 scatteringIFT laser-light scattering• Best suited for low values (< 30 mN/m)• Measurement range is 102 – 10-5 mN/m

• Method has been successfully applied down to 10-4 mN/m

Bacterum: Dietsia maris

D d k bi th ti t

100OW IFT

Dodekan, aerobic synthetic sea water

10

OW IFTOWB IFT4.0 ml/h0.9 ml/h1.8 ml/h

0,1

1

IFT

(mN

/m) 1.8 ml/h

2.7 ml/h5.4 ml/h

0,01

0,0010 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 theand Strand, K.A., 2005, Interpretation of Microbial Oil Recovery from Laboratory Experiments , Paper presented at the13th European Symposium on Improved Oil Recovery, Budapest, Hungary, Apr 25-27

Hopeman sandstone coreL b t i t 45 cm long, 5 cm diameter

Statfjord model oil

Fl t 0 1 l/ i 1 PV/d

Laboratory experiments

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

Anoxic synthetic0,38

Sor Anoxic synthetic seawater

Microbes, O2, N, P

0,36

, , ,

0,34

0,320 5 10 15 20

Time (days)

MEOR at Norne

Injection of aerobic seawater from start in 19971997

MEOR implemented in January 2001 by adding N and P to the injection water toadding 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 NorneMEOR at Norne

2002: Increased oil production from MEOR at Norne

– 900 000 m3

– 1 % of producible oilp

– 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 )