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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
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