SPE 123506. Microbial Enhanced Oil Recovery: An Investigation of Bacteria Ability to. Live and Alter Crude Oil Physical Characteristics in High Pressure.
SPE 123506 Microbial Enhanced Oil Recovery: An Investigation of Bacteria Ability to Live and Alter Crude Oil Physical Characteristics in High Pressure Condition Amalia Yunita Halim, OGRINDO-ITB; Umar Dani Fauzi, Mathematics-ITB; Septoratno Siregar, SPE, Petroleum Engineering-ITB; Edy Soewono and Agus Yodi Gunawan, Mathematics-ITB; Dea Indriani Astuti, SITH-ITB; and Nuryati Juli, OGRINDO-ITB
Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE Asia Pacific Oil and Gas Conference and Exhibition held in Jakarta, Indonesia, 4–6 August 2009. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.
Abstract pressure condition decreases by 18,84% in 250 psi and Indonesia has officially declared its withdrawal
6,09 % in 500 psi; further investigation after 7-days
from OPEC membership in September 2008 because of
showed that IFT decreases by 27,54 % in 250 psi and 9,33
failing to meet its oil production quota as what is
% in 500 psi. The mathematical model shows that the
determined.
and
maximum production of bacteria increases with the
environmentally friendly methods need to be applied in
increase of the initial input of bacteria, and the higher the
Indonesian reservoirs; one of them is Microbial Enhanced
pressure is, the faster the bacteria growth is. It can be
Oil Recovery (MEOR). This method involves the
concluded that the bacteria are able to live in high
knowledge of biotechnology and petroleum engineering
pressure (piezophile bacteria) and give positive impact to
and is aimed to improve oil recovery in old and marginal
the crude oil by decreasing its viscosity and reducing the
wells.
This paper presents laboratory investigation of
IFT hence improve oil mobility. It is predicted that by
bacteria ability to live and alter crude oil physical
applying this method Indonesia crude oil production can
characteristics in high-pressure condition of 250 psi and
be improved or at least the production decrease can be
500 psi, provided with a mathematical model for further
slowed down.
For
that
reason,
effective
analysis. The experiment was conducted in a special apparatus called conditioning cells, which is made of
Introduction
stainless steel. Data obtained from the investigation are then used to make a mathematical model and simulation
Having been exploited for more than 100 years,
for analysis and prediction. After 3-days of treatment by
the oil production in Indonesia is now facing a very
bacteria in high pressure condition, oil viscosity decreases
serious problem due to production declines (Yusuf et al.,
by 11,27 % in 250 psi and 11,88 % in 500 psi; further
1999). Indonesia has become a net oil importer since 2003
investigation after 7-days showed that oil viscosity
and in September 2008 Indonesia officially withdrew its
decreases by 22,48% in 250 psi and 20,70% in 500 psi.
membership from OPEC (Petrominer, 2008).
The IFT after 3-days of treatment by bacteria in high
For that reason, enhanced oil recovery (EOR)
2
SPE 123506
method needs to be applied in Indonesia reservoir to
6.
the capacity to use the foodstuffs anaerobically
increase Indonesian oil production. Microbial Enhanced
(i.e. in the absence of oxygen gas) since
Oil Recovery (MEOR), as a tertiary oil recovery method
molecular oxygen cannot be provided in
is highly relevant to Indonesia because the high diversity
sufficient amounts down-hole to last perhaps for
of its microorganisms (Halim et.al, 2008c).
years on end 7.
a biochemical constitution commensurate with the production in adequate quantities of an
Benefits and Limitations
effective agent to promote mobilization of crude MEOR has several benefits compared to other EOR techniques, especially because this system offers
oil 8.
the absence of any unacceptable properties
multiple and simultaneously occurring mechanisms that
which might lead to plugging of the formation
can help to release the trapped oil in reservoir formation.
with a consequent fall in permeability, or the
The benefits of MEOR process are production of several
production of chemical substances causing
biological products such as biosurfactant, bioacid,
deleterious
biopolymer, biosolvent and gases. In addition this
downstream, etc.
biological
process
also
offer
continue
changes
in
the
oil,
corrosion
and
environmentally friendly process.
Previous Laboratory Experiment
However, there are several limiting factors that are likely to inhibit the successful of MEOR. These are
The bacteria used in this experiment were
some essential characteristics need to be investigated
isolated from brine and oil sample from an oil reservoir in
before
Kalimantan. The bacteria were then identified and tested
microbes
are
applied
in
MEOR.
Those
characteristics are (Moses and Springham, 1982) 1. 2. 3.
4.
their potential to be applied in MEOR (Solihah, 2006).
small in size, to permit most ready penetration
The investigation revealed that the bacteria were small in
through rock strata
size so that they can penetrate into the core pores and they
resistance to high pressure since many reservoirs
were able to live in high temperature environment (Halim
are deep
et al., 2008a). The core flooding experiment showed that
maximum tolerance of the high temperatures
the bacteria could increase oil recovery and also slightly
prevailing in a large number of economically
caused selective plugging in the cores samples (Halim et
important reservoirs
al., 2008b).
ability to withstand brines and sea water, since these are often present in reservoirs or used for
Research focus in this paper
waterflooding 5.
non-fastidious
nutritional
requirements,
the
This paper focuses on the bacteria ability to
simpler the better. The ability to live and thrive
survive in anaerobe and in high-pressure environment.
on the simple mineral salts already present (or
These two conditions are considered as a major concern
cheap and easy to add) in the waterflood, plus
in the successful of MEOR application because they limit
the facility to use part of the crude oil in situ as a
the bacterial growth. Microbial degradation of oil
carbon and energy source, are highly desirable
hydrocarbon in anaerobic condition is by itself an
properties
important problem both for the theoretical and applied research (Rozanova, et al., 2001). Additionally, high-
SPE 123506
3
pressure condition can contribute to the denaturation of
in Kalimantan. The bacterial inoculum concentration used
bacterial protein hence lead to bacterial death. The
was 10% at a density of about 106 -107 cells/mL. The first
bacteria used in MEOR application usually are piezophile
step was the bacteria inoculation into the recovery
bacteria, which can survive and grow well in high-
medium. In this study, we define the oil which was
pressure condition. Piezophile or pressure loving-bacteria
inoculated by bacteria as “the System”. The second step
can live up to 130 Mpa (18854.91 psi) (Rothschil &.
was the System incubation in a rotary shaker incubator of
Mancinelli. 2001).
60ºC for 3 days, with agitation of 120 rpm. The second
This paper presents data of the bacteria ability to live in anaerobe condition and high-pressure condition.
step was repeated 3 times in order to get bacteria in their active condition.
The pressure applied is 250 psi and 500 psi. The data are then used to make a mathematical model and simulation
Investigation of bacterial growth and their abilities to
using MAPLE 9 software.
alter crude oil in high pressure and anaerobic condition (without oxygen).
Material and Methods This experiment was aimed to check the bacteria ability to live in high pressure with limited oxygen amount in the
Materials
environment, as this is always become a limiting factor The bacteria used in this experiment, namely as Bacillus
for the successful of MEOR application. Four Erlenmeyer
polymyxa and Bacillus sp, were isolated from crude oil
flasks containing 250 mL of recovery medium and 20%
and brine samples of an oil reservoir in Kalimantan. Both
of crude oil were provided, they are labeled as A, B, C,
bacteria has been proven to be give positive impact to
and D. The flasks which were labeled as A and B were
crude oil characteristics by decreasing crude oil viscosity,
used for investigation of bacteria ability to live in 250 psi,
density and interfacial tension (IFT) in aerobic condition
A was inoculated by the mixed culture of Bacillus
(Solihah, 2006). There were two medium used in this
polymyxa and Bacillus. sp treatment while B was used as
experiment. The first was recovery medium, containing
a control (without bacteria inoculation). The flasks, which
one litre connate water; amonium nitrate (0.5%); molasses
were labeled as C and D, were used for investigation of
®
(2%) (Solihah, 2006). The second was Difco Nutrient
bacteria ability to live in 500 psi; C was inoculated by the
Agar (NA) as the general medium to grow the bacteria.
mixed culture of Bacillus polymyxa and Bacillus. sp
The crude oil and brine samples were collected from an
treatment while D was used as a control (without bacteria
Oil Reservoir in Kalimantan.
inoculation). The bacterial inoculum ratio was 1:1 and inoculum concentration was 10% (v/v) at about 106 -107
Methods
cells/mL. The age of the bacterium cell was in the half log of its growth phase. The liquid inside A, B, C and D was
Bacterial activation
then aseptically poured into conditioning cells made of stainless steel (figure 1), each cell for each flask. After
In this part of experiment, the bacteria were activated in
that the conditioning cells were then vacuumed and
aerobic condition to ensure that the bacteria were in their
injected by 250 psi of nitrogen for A and B; and 500 psi
active condition and to reduce the lag phase of the
of nitrogen for C and D. The conditioning cells were then
bacteria. The bacteria were activated in the recovery
incubated in an incubator at 60ºC for seven days. On the
medium containing 20% of crude oil from an oil reservoir
third and seventh day of the incubation 2 mL of the
4
SPE 123506
sample was taken from each cells, 1 mL for counting the
the data the simulation of the model is done with MAPLE
bacterial cell number and 1 mL for measuring the medium
9 software to simulate the dynamics of bacteria and
pH. In addition, crude oil physical characteristics changes
biosurfactan. The parameters
(viscosity, density and IFT) were also observed.
μ1 , μ 2 are
estimated from
the early growth (during the first day), assuming that the growth is still nearly exponential. The rest of parameters
Mathematical modeling of bacteria and biosurfactant
are estimated by curve fitting.
and Simulation of the model Oil The mathematical model simulates the experiment which
Physical
Characteristics
Post-Treatment
by
Bacteria
is conducted in laboratory. The model consists a coupling and the growth of
Oil density was measured by Pyrex picnometer. Viscosity
biosurfactant being produced by the bacteria. The growth
was measured by Ostwald Fenske Viscometer type 350 A
of bacteria is modeled by a logistic growth with toxicity
469. Interfacial tension was measured by DuNuoy
factor due to interaction with biosurfactan. This equation
Processor Tensiometer mode 21 O-ring = 6 cm.
between the growth of bacteria
is coupled with a predator-prey type equation for the biosurfactan.
Result and Discussion
The bacteria growth model is modeled by the The investigation has revealed that the bacteria
equation
μ P 2 (t ) dP ( t ) = μ1 P (t ) − 1 − γ P (t ) S (t ) dt K0
are facultative anaerobe as they can live with or without the presence of oxygen. In addition, these bacteria are also piezophiles, as they did not die when the pressure
where P (t ), μ1 , K 0 are the density, growth rate, and
was increased until 250 and 500 psi. Table 1 shows the
carrying capacity of bacteria, respectively, S (t ) is the density of biosurfactan, and γ is toxicity interaction factor due to the increase of biosurfactan.
bacteria log cell number during the 3rd and 7th day of incubation. If we compare it with the previous laboratory research (table 2), it can be seen that the bacteria can live better and also produce more acid if the pressure is
The biosurfactant growth model can is given by the equation
dS (t ) = μ 2 P(t ) − δP(t ) S (t ) dt
and
δ
where μ 2 is the production rate of biosurfactan, is the predation factor.
increased.
This
happen
because
pressure
favors
piezophiles bacterial growth by stabilizing their proteins, increasing their activities (Gilis, 1994) and also increasing the proportion of unsaturated fatty acids in their membranes (Bartlett & Bidle, 1999). It can be concluded that the bacteria used in this experiment are piezophiles bacteria because if the bacteria are not barotolerance or sensitive to pressure changes, they will fail to grow at pressure greater than atmospheric pressure. Pressure
It is assumed, as shown from the data, that at the initial
limits the growth of non-barotolerance because when
stage (at the time t1 = 12 hours) there is a significant
pressure increases the molecules in lipid membranes pack
reduction of bacteria due to environmental adjustment.
tighter, resulting in decreased membrane fluidity. (Pledger
The initial condition for bacteria is taken at t1 the from
et.al, 1994). Additionally, high pressure can alter gene expression (Nakasone et al., 1998) and also damage DNA
SPE 123506
5
and particularly proteins (Abe & Horikoshi, 1999).
between oil and brine water. It is also supported by
Investigation by Barlett and Ellen Chi revealed that the
previous lab research which showed that these two
gene, which is associated with pressure adaptation, is the
bacteria produce biosurfactant (Halim et al., 2008b).
outer membrane gene called ompH and regulatory locus
It is shown from the simulation that the maximum
called ompJ (Gillis, 1994).
production of bacteria increases if we increase the initial
Besides the bacterial growth, the bacterial ability
input of bacteria. As illustrated in Figure 3, if the initial
to alter the crude oil physical characteristic (density,
condition is increased by 24.19 %, the maximum density
viscosity, IFT) is also observed. Viscosity is a parameter
of bacteria increases by 24 %.
used to determine how easily fluids flow; the lower the
Besides the crude oil, the bacteria also change the
viscosity the easier fluids flow. The bacteria used in
medium water characteristics (density and viscosity). This
MEOR should have the ability to reduce oil viscosity.
can be seen in the figure 7 and 8 that water density and
Figure 4 shows the bacteria ability to alter the viscosity. It
viscosity decreased. It means that some materials inside
can be inferred from the figure that after 3 days of
the water were used by bacteria, the water density
incubation, the bacteria decrease oil viscosity by 11,27%
decrease was better in higher pressure. This result was
in 250 psi and 11,8% in 500 psi. Further investigation
supported by the log cell number result (table 2). This
showed that the bacteria decrease oil viscosity by 22,48%
happened because more bacteria live in 500psi so more
in 250 psi and 20,70% in 500 psi after 7 days of
materials were used by bacteria.
incubation. This means that the bacteria not only able to live in high pressure environment but also give positive
Conclussions
impact to the crude oil by decreasing its viscosity. This is supported by previous laboratory research which revealed
•
The bacteria used in this experiment, namely as
that the bacteria could degrade the crude oil (Solihah,
Bacillus polymixa and Bacillus sp are piezophiles
2006) and also produced gases (Halim et al., 2008b).
bacteria because they can grow in high pressure
Bacteria activities in degrading crude oil also give
environment.
contribution to the changes of oil density. In general, oil
•
Based on the mathematical model it can be assumed
density can be describe as oil weight per unit volume or
that the bacteria growth better as we increased the
oil weight compared with water weight in standard
initial condition of bacteria.
condition (60ºF, 14 psi). Oil density is affected by its physical characteristics (Halim et al., 2008a). The density
Acknowledgement
changes are depicted in figure 5. The figure shows that the oil was slightly degraded by bacteria so that the oil
The authors want to say thank you to OGRINDO (Oil and
fraction did not change totally and still classified in the
Gas Recovery for Indonesia) for the financial funding
intermediate fraction (between 20-30 ºAPI gravity).
during the research and to Total E&P Indonesie for the
rd
th
Figure 6 shows the IFT decrease after 3 and 7 day of
brine and crude oil samples
rd
incubation. After 3 day of incubation IFT decrease by 18,84% in 250 psi and 6,09 % in 500 psi. Further
Nomenclature
investigation showed that the bacteria decrease oil viscosity by 27,54 % in 250 psi and 9,33 % in 500 psi after 7 days of incubation. This result showed that the bacteria produce biosurfactant which can reduce the IFT
P(t) S(t) µ1 K0
= the number of bacteria in time t = the number of biosurfactant in time t = growth rate of bacteria = initial carrying capacity
6
SPE 123506
Pressure = Pressure (Psi) t = time β, γ, α, δ, ε = constant. µ2 = growth rate of biosurfactant µ21 = growth rate of biosurfactant 1
Petrominer. No 10 vol xxxv (October 15, 2008) 38-39. Pledger, R. J., Crump, B. C., Baross, J. A.: “A barophilic
response
by
two
hyperthermophilic,
hydrothermal vent Archaea: an upward shift in the optimal temperature and acceleration of growth rate at
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SPE 123506
7
Crude Oil Viscosity 1,8 1,6
viscosity (cP)
1,4 1,2 1 0,8 0,6 0,4 0,2 0 250
Control
3 days
500
pressure (psi)
7 days
Viscosity
Decrease percentage (%)
days
250 psi
3 days
Figure 1. The result of simulation bacteria growth model compare with the data in the 7 days.
7 days
500 psi
11,270
11,878
22,476
20,697
Figure 4. Oil viscosity decrease after 3rd and 7th day of incubation.
Crude Oil Density 31
30
o
density ( API )
30,5
29,5 29 28,5 28 250
Control
Figure 2. The result of simulation biosurfactant
3 days
7 days
Density
growth model compare with the data in the 7 days.
500
pressure (psi)
Decrease percentage (%)
days 3 days 7 days
250 psi
500 psi
0,057
0,069
0,125
0,137
Figure 5. oil density decrease after 3rd and 7th day of incubation.
Figure 3. The result of simulation which the initial condition increased compare with the data in the 7 days.
8
SPE 123506
Table 1. bacteria log cell and medium pH changes
Interfacial Tension (IFT) 16
during incubation in 250 psi and 500 psi
IFT (dyne/cm)
14 12 10 8 6 4 2 0 250
Control
3 days
7 days
IFT
500
pressure (psi)
days
250 psi
3 days 7 days
Table 2. bacteria log cell and medium pH changes
500 psi
18,841
6,086
27,536
9,331
Figure 6. Interfacial tension decrease after 3rd and 7th day of incubation.
Water density 0,984
density (gram/ml)
0,983 0,983 0,982 0,982 0,981 0,981 250,000
3 days
7 days
500,000
pressure (psi)
Figure 7. Water density decrease after 3rd and 7th day of incubation.
Water viscosity 0,500 0,450
viscosity (cP)
0,400 0,350 0,300 0,250 0,200 0,150 0,100 0,050 0,000 250,000
Control
3 days
250 psi 500 psi 7,23 7,20 7,51 8,80 6,04 6,20 7 7 5,5 5 5 4,5
Decrease percentage (%)
Control
Treatment Log cell 0 day number 3 days 7 days pH 0 day 3 days 7 days
7 days
500,000
pressure (psi)
Figure 8. Water viscosity decrease after 3rd and 7th day of incubation.
during incubation in 50 psi (Saputra, et. Al., 2008)
Treatment Log cell 0 day number 3 days 7 days pH 0 day 3 days 7 days
50 psi 7,53 6,25 5,75 7 5,5 5
