International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1378

ISSN 2229-5518

A REVIEW OF MICROBIAL ENHANCED OIL RECOVERY: CURRENT DEVELOPMENT AND FUTURE PROSPECTS

O.A. Omoniyi,F,Abdulmalik

ABSTRACT-Microbial Enhanced Oil Recovery (MEOR) is a tertiary oil recovery technique that employs the use of microbes and their byproduct to enhance residual oil mobilization in the reservoir

This work considers MEOR technology application based on economic, technological and environmental stand point as against other EOR techniques. Successful field trials are studied and their success stories analysed. The technology (MEOR) is not without some limitations which shall be overcome with constant research and field application/field trial.

It has the potential to be one of the reliable technologies that best suits the economic constraints of the current oil markets. The technology is a potential alternative to other EOR method as it is being implemented in most parts of the world with satisfactory results not only from economics point of view but also from having lesser environmental impact.

Microbial EOR (MEOR) processes have several unique characteristics that may provide an economic advantage. Microbial processes do not consume large amounts of energy as do thermal processes, nor do they depend on the price of crude oil as many chemical processes do. Because microbial growth occurs at exponential rates, it should be possible to produce large amounts of useful products rapidly from inexpensive and renewable resources.

The microbial metabolic products that include bio-surfactants, biopolymers, acids, solvents, gases, and also enzymes modify the properties of the oil and the interactions between oil, water, and the porous media, which increase the mobility of the oil and consequently the recovery of oil especially from depleted and marginal reservoirs; thus extending the producing life of the wells

The review concludes that MEOR is a viable option for increasing oil recovery world over.

Keywords: Microbial Enhanced Oil Recovery (MEOR), Microbe, Recovery, Improved oil recovery, Residual oil

——————————  ——————————
1.0 INTRODUCTION
Nowadays, the majority of the world’s energy comes from crude oil. A large proportion of this valuable and non- renewable resource is left behind in the ground after the application of conventional oil extraction methods. Moreover, there is a dire need for/to produce more crude oil to meet the worldwide rising energy demand which illustrates the necessity of progressing enhanced oil recovery (EOR) processes.
Enhancement of the amount of hydrocarbons recovered
from existing reservoirs is slowly becoming a standard procedure during the operational life of an oil field. Much research is presently being channeled into this area with the effect that both new and old methods are being carefully evaluated. Microbial Enhanced Oil Recovery (MEOR) is one such scheme which has received favorable reevaluation.
One of the major factors in the selection of any recovery
method is the economic potential of the remaining reserves.
In the past, much of the oil was left behind in the reservoir
especially in the marginal and mature reserves due to the
absence of a cost effective method.
But, in today’s energy sector where oil prices are at their
highest level ever reached, the development of the marginal
and/or uneconomical reserves cannot only brings such reserves to production but could also help the operators to get maximum profit from these reserves.
These methods try to overcome the main obstacles in the way of efficient oil recovery such as the low permeability of some reservoirs, the high viscosity of the crude oil, and high oil-water interfacial tensions that may result in high capillary forces retaining the oil in the reservoir rock pores. One of the recovery methods which has the vast potential of bringing such reserves to production is the Microbial Enhanced Oil Recovery (MEOR). It is a chemical EOR method but with chemical generated in situ. It has been a main topic of research and interest in the past years and has long been expected to offer a low-cost approach for improving recovery.
MEOR is one of the EOR techniques where bacteria and
their byproducts are utilized for oil mobilization in a
reservoir. In principle, MEOR is a process that increase oil
recovery through inoculation of microorganism in a
reservoir, aiming that bacteria and their byproducts cause some beneficial effects such as the formation of stable oil- water emulsions, mobilization of residual oil as a result of

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1379

ISSN 2229-5518

reduced interfacial tension, and diverting of injection fluids through upswept areas of the reservoir by clogging high permeable zones. Microbial technologies are becoming accepted worldwide as cost-effective and environmentally friendly approaches to improve oil production (Sarkar et. al, 1989)1.
Microbial Enhanced Oil Recovery (MEOR) is one of the
technologies that can be potentially implemented with an
exceptionally low operating cost: It has several advantages
compared to conventional EOR processes as it does not consume large amounts of energy as do thermal processes, nor does it depend on the oil price as do many chemical processes. MEOR is simply the process of utilizing microorganisms and their bio-products to enhance the oil recovery. Bacteria are the only microorganisms used for MEOR by researchers due to their small size, their production of useful metabolic compounds such as gases, acids, solvents, bio-surfactants, biopolymers as well as their biomass. Also, their ability to tolerate harsh environments similar to those in the subsurface reservoirs in terms of pressure, temperature, pH and salinity increased their attraction to be used for EOR purposes6.
This technology (MEOR) is said to be capable of producing
up to 50% of the residual oil (Lazar et al. 2007; Sen, 2008)3,
4. The field trials have shown that normal projected oil
production decline curve can be reversed or level off by MEOR and the reason is because microbial growth and metabolites produced can have effects on the chemical and physical properties of reservoir rocks and crude oil (Hitzman, 1994)16.
Problem Statement
Crude oil is produced on a daily basis. However, a large
portion of this valuable energy source is left underground
after the application of conventional extraction methods.
The rising global energy demand has prompted the oil
industry to explore other viable recovery techniques. Objective
To examine Microbial Enhanced Oil Recovery and its technology
To analyse why the technology has not been widely used as
other conventional techniques.
To see the potential of Microbial Recovery in competing
with other conventional recovery methods.
Methodology
a review on:
History and background information on Microbial
Enhanced Oil Recovery, MEOR
The MEOR technology and its implementation status
Research conducted on MEOR (papers and journals)
How MEOR compares to other Enhanced Oil Recovery
(EOR) techniques
3.1 HISTORY OF MEOR
MEOR was first described by Beckman in 1926 (Lazar et.
al., 2007)3. Few studies were conducted on MEOR over 2
decades after Bachman has described it. Until later in 1947,
ZoBell initiated a new era of petroleum microbiology with
applications for oil recovery. He conducted a series of field
tests and discovered that bacteria can release oil from sedimentary materials. After the tests, ZoBell explained that the mechanisms which are responsible for bacterial oil release involved processes such as:
Production of gaseous C02
Production of Organic acids and detergent
Dissolution of carbonates in the rock
Physical dislodgement of the oil (Zobell, 1947)9.
The first MEOR test was conducted in the Lisbon field,
vision country, Arkansas in 1954 (Yarbrough and Coty,
1983)10. The improvement of MEOR in field trials was
based on the injection of mixed anaerobic Bacteria such as
Clostridium, Baccilus, Pseudomonas etc. and are selected
based on certain tendencies they exhibit.
The application of MEOR as a tertiary recovery technique and a step to decrease residual oil saturation has been explained (Behesht et. al. 2008)11. The aspect of petroleum microbiology that is perhaps the most important for MEOR is the ability of the microbes to use hydrocarbons as the carbon and energy source. The development of Biotechnology research has influenced the oil industry to be more open to the evaluation of microorganism to enhance production. Both the in situ and injected microorganism are used depending on their adaptability to the reservoir that is being used. In MEOR, bacteria are used because they show several practical features (Nielson et al, 2010)12.
3.2 PROCESSES OF MEOR
There are 2 main processes of MEOR depending on
the site of the bio-product production. They are namely in
situ and ex situ processes.
The in situ process involves producing the bacterial bio- products inside the reservoir. It can be done either by stimulating the indigenous reservoir microbes or injecting specially selected consortia of bacteria that will produce specific metabolic products in the reservoir which will lead to enhancement of oil recovery (Jack and Steheier 1988)13. According to Jang et. al., the success of an in situ MEOR process depends on the selection of the candidate reservoir, the proper choice of potential bacterial species, the viability of the bacteria under reservoir conditions, the amount of metabolites generated and their effects on releasing residual oil. Care must be taken however when nutrients or sulphate-containing waters are injected to ensure that indigenous sulphate-reducing bacteria (SRB) are not stimulated or overgrown by the injected microbes. These SRBs play a very negative role in MEOR due to the production of hydrogen sulfide, H2S (Bass 1997)14. The major concerns of global oil industry with SRBs include souring of oil, corrosion caused by the production of H2S, plugging by iron sulphide etc. (Brown, 2010)15. A concept is patented by Hitzman (Hitzman, 1994)16 of adding a biocide to the water in water flood to inhibit SRB.
The ex situ process involves the production of the bio-
product at the surface outside the reservoir then injecting
them separately either with or without the separation of the
bacterial cells. In ex situ process, where exogenous
microbes are introduced into the reservoir, it is important

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1380

ISSN 2229-5518

to conduct capability studies to determine the interaction of the injected microbes with the indigenous ones (Bryant,
1989)7.
3.3 CANDIDATE MICROBE FOR MEOR
Microbes can be classified in terms of their oxygen intake
into 3 main classification; Aerobes; where the growth
depends on abundant supply of oxygen to make cellular
energy. Strictly Anaerobes which by contrast are sensitive
even to the lowest oxygen concentration and are found in
deep oil resources. These anaerobes do not contain the appropriate complement of enzymes that are necessary for growth in aerobic environment (Pommerville, 2005)17. Most successful field experiments used the anaerobic bacteria (Mandgalya et. al., 2007)8.
There are many sources from which bacterial species that are MEOR candidate can be isolated. Lazar explained four main sources that are suitable for bacterial isolation (Lazar,
1991)18. These are
Formation waters
Sediments from formation water purification plants
(Gathering stations)
Sludge from biogas operations
Effluents from sugar refineries
Nutrients are the largest expense in the MEOR processes
where formulation medium can represent almost 30% of
the cost for a microbial fermentation (Rodrigues et. al.,
2006)19. The microbes required mainly 3 components for growth and metabolic production: Carbon, Nitrogen, and phosphorous sources. Generally in the ratio C.100: N.10: P.1. The optimization medium is very important since the type of bio-products that are produced by different types of bacteria are dependent on the type concentrations and components of the nutrients provided. The third classification of bacteria is the facultative microbes which can grow either in the presence or reduced oxygen concentration.
3.4 MEOR MECHANISMS
Improving oil recovery through microbial actions can be
performed through several mechanisms such as reduction
of oil water Interfacial Tension (ITF) and alteration of
wettability by surfactant production and bacterial presence, selective plugging by microorganisms and their metabolites, oil viscosity reduction, degradation of long chain saturated hydrocarbons and production of acids which improves absolute permeability by dissolving minerals in the rock. The microorganism produces a variety of metabolites that are potentially useful for oil recovery (McInerney, 2002)20.
There are six main bio-products/metabolites, produced by microbes. The table below shows a summary of these bio- products and their application in oil recovery (McInerney,
2002)20.

3.4.1 Biomass
Bacteria are known to grow very fast as some are reported to multiply 20 times under aerobic conditions (Pommerville, 2005)17. The mechanism of the microbial biomass in MEOR involves selective plugging of high permeability zones where the microbial cell will grow at the layer pore throats restricting the undesirable water flow through the pores (Jack and Steheier, 1982)13. This will force the displacing water to divert its path to the smaller pores and hence displacing the un-swept oil and increasing the oil recovery.
3.4.2 Bio-surfactants
These are amphipathic molecules with both hydrophilic and hydrophobic parts which are produced by variety of microorganisms. They have the ability to reduce the surface and interfacial tension by accumulating at the interface of immiscible fluids and increase the solubility and mobility of hydrophobic or insoluble organic compounds. Bio- surfactants are high value products that due to their superior characteristics such as low toxicity, ease of application, high biodegradability and tolerance even
under extreme conditions of PH, temperature and salinity are efficient alternatives to chemically synthesized surface active agents with potential application in the oil industry.
3.4.3 Biopolymers
These are polysaccharides which are secreted by many
strains of bacteria mainly to protect them against
temporary desiccation and predation as well as to assist in
adhesion to surfaces (Sen, 2003)4 and (Brown, 1992)21. The proposed processes of biopolymers are mainly selective plugging of high permeability zones and this permeability modification of the reservoir to redirect the water flood to oil rich channels (Sen. 2008)3. Another important process of biopolymers is their potential as mobility control agents by increasing the viscosity of the displacing water hence improving mobility ratio and sweep efficiency (Akit et. al.,
1989)22.
3.4.4. Bio-solvents
Sometimes solvents can be produced as one of the metabolites of the microbes. These include ethanol, acetone, and butanol by carbohydrates fermentation during the initial growth phase of the germination process. Strains of

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1381

ISSN 2229-5518

anaerobic bacteria such as chloride are responsible for the production of the metabolites during the stationary growth phase of the presentation process. These bio-solvents may also help in the reduction of oil viscosity and can also contribute as a surfactant (Co-surfactant) in reducing the interfacial tension (IFT) between oil and water (Youssef et al, 2005)23.
3.4.5 Bio-acids
Some bacteria, under certain nutrients can produce acids such as lactic acids, acetic acid and butyric acid (McInerney et. al., 2005)24. These acids can be useful in carbonate reservoirs or a sandstone formation sandwiched by carbonates, since some of these cause dissolution of the carbonate rock and hence improve its porosity and permeability (McInerney et al, 1990)25. Production of organic acids by bacteria is a normal phase of anaerobic formation of sugar. Clostridium sp, for example can produce 0.0034 moles of acid per kilogram of molasses. (Gray et.al., 2008)26.
3.4.6. Biogas
Bacteria can ferment carbohydrate to produce gases such
as carbon dioxide, hydrogen and methane gases. These
gases can be used for enhancing oil recovery by exploring
the mechanisms of reservoir re-pressurization and heavy
oil viscosity reduction. The gases can contribute to the pressure build-up in pressure depleted reservoir (Brown,
1992)21. They (gases) may also dissolve in crude oil and reduce its viscosity (Ramsay, 1987)27 and (McInerney et al,
1990)25 some of the reported gas-producing bacteria are
Clostridium, Desulfovibrio, Pseudomonas and certain methanogens (Behlulgil and Mehmetoglu, 2003)5. Methanogens produce about 60% methane and 40% carbon dioxide where the methane will partition between oil and gas phase while carbon dioxide will partition to the water phase as well and hence improve the mobility of oil (Gray et al,2008)26.
3.5 MEOR FIELD TRIALS
MEOR method was developed from laboratory based
studies (Ramkrishna, 2008)28. There are two main purposes
to go for MEOR field applications, as single well treatment and full field treatment.
Single well treatment includes well simulation, wellbore clean-up and others. In this treatment process, improvement in oil production can result from removal of paraffinic or asphaltic deposits from the near wellbore
region or from mobilization of residual oil in the limited volume of the reservoirs that is treated (Bryant, 1989)7.
Full field treatment includes microbial enhanced water flooding and other processes that involve both injection and production wells. Here, the microbes and nutrients are
injected through an injector well where the metabolites will be produced in situ such as biopolymers that will help in mobility control of the water flooding.
MEOR process variables must be optimized before it develops into a practical method for common field trials or
application. These variables includes a better description of
the candidate reservoirs, better knowledge of the biochemical and physiological characteristics of the microbial consortia, a better handling of the controlling mechanisms, and an unambiguous estimation of the process economics. Most of the MEOR processes leading to field trial have been completed in the last two decades and now the knowledge has advanced from a laboratory based assessment of microbial processes to field applications globally (Ramkrishna, 2008)28.
Some selected field projects across the world are analyzed and discussed, these project represents a diverse geographic and geologic mixtures. MEOR case studies of successful projects as analyzed by Dietrich et. al., (1996)29 is used in this review. The projects are located across the United States of America (USA) Argentina and the People Republic of China.
3.5.1 MEOR Treated Projects (Case Studies)
Dietrich et al (1996)29 analyzed five commercial projects as
case study. These projects were recorded to have increased
oil production significantly as compared to oil production prior to MEOR application. Two of these projects are located in the USA, one in Argentina and the other two in the people Republic of China.
3.5.1.1 San Andrews Project
The San Andrews reservoir was discovered in 1945 and
was produced by solution gas drive until 1967 when water flooding was started. The original oil in place was
355bbl/acre-ft, at 70% oil saturation. When MEOR technique was employed in the October of 1994, oil in place was 239bbl/acre-ft with an oil saturation of 41%. Rock
properties are relatively inhospitable for microbes. The low
1.7md average horizontal permeability would normally be
indicative of pore throat size well below what microbes
could enter. However most of the oil is produced from
natural fractures which the microbes can penetrate.
Reservoir temperature at 1150F is ideal for microbe growth.
3.5.1.2 Treatment
The treatment consisted of ten barrels of microbe laden
water down the annulus. On the initial treatment the wells
were shut-in for three days. Subsequently, they have been
shut-in overnight. For the first three months the well were treated every 14 days, thereafter approximately every
28days.
3:5.1.3 Evaluation
The reservoir was stabilized on a consistent 6.5% per year
decline for three years before MEOR was begun. The
decline was flattened to 0.6% per year. Water production on this property is blended with fresh water and injected. Produced water is measured only by well tests and is not accurate enough to draw a conclusion regarding reduction in water cut. Over a period of 19 months 17,000 barrels of incremental oil have been produced which is seven percent (7%) over the baseline. Current oil production of 440 barrels per day is 10% over the baseline. The incremental increase is expected to reach 15% by the end of the project life.
At the end of its life, the water flood would have lift oil in
place 205bbl/acre-ft versus 199bbl/acre-ft with MEOR.

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1382

ISSN 2229-5518

Residual oil saturation is projected to decrease from 35%
under water flood to 34.1% with MEOR.
3.5.2 Queen Sand Project
This reservoir was discovered in 1984 and was quickly water flooded due to its very low solution gas content. Injection was began in 1990 and oil production increased quickly from 200 to 2,500 barrels per day. This rate continued until late 1991 when a rapid decline began. At the start of MEOR in August of 1992, oil in place was
728bbl/acre-ft with an oil saturation of 56%.
Rock properties are generally favourable for microbe
colonization. Average permeability is 13md with an upper
limit of 300md and provides adequate pore throat size for
microbes to colonize. Additional permeability developed
by fracture treatment with 60,000 gallons and 135,000 pounds of sand on initial completion provided excellent porous media for microbe colonization. Reservoir temperature at 1100F is ideal for microbe growth. Average production per well is 42 BOPD at 74% water cut. The wells are rod pumped with low producing fluid levels. The formation contains salt and anhydrite and formation water is saturated brine.
3.5.2.1 Treatment
Over the first nine months of MEOR treatments 11 of the 18
wells were treated with 400 to 450 barrels of microbe-laden
water squeezed down the annulus followed by a 3 day shut-in. Three more similar squeezes were performed later. Routine batch treating was later begun in September of
1992. The wells were treated weekly with 32 barrels of microbe-laden water followed by a 6-12 hours shut-in. In
late 1994, the frequency was reduced to every 14days. Then in early 1995, the frequency was increased only on selected wells back to every 7 days.
3.5.2.2 Evaluation
The reservoir was on a 39% per year decline for 10months
before MEOR was begun. The decline flattened for several months, and then resumed at 31% per year. In late 1994, the injection pattern was altered by the conversion of two wells from producers to injectors and the injection rate has increased. Although the benefits of MEOR continue, comparison to the original baseline was inaccurate. Water production continued to increase after the start of MEOR. The rate of increase in water-cut decreased from 24% per million barrels to 12%. Over the first 24 months 240,000 barrels of incremental oil was produced which is 34% over the baseline. Oil production at the time the injections pattern was changed was 1000bbls/day, 43% over baseline. The cumulative incremental increase was projected to be
47% by the end of the project life.
At the end of its life, the water flood before the pattern
changes would have left oil in place 691bbls/acre-ft versus
660bbls/acre-ft with MEOR. Residual oil saturation was projected to decrease from 51.4% under water flood to
49.1% with MEOR.
3.5.3 Tapun Gato-Refugio Project
The field was discovered in 1930 the three wells in the
project were complete in 1940, 1979 and 1786 in the Victor
Oscuro formation. The reservoir has been produced by a combination of solution gas drive, water drive and water flood. MEOR was started on one well in June 1994 and on the other two wells in March of 1995. Production was time- normalized relative to the start of MEOR. At the start of the project oil in place was 625bbl/acre-ft with an oil saturation of 47% and an oil saturation of 10%. The wells are on approximately 42 acre spacing. Rock and fluid properties are favourable for microbe colonization.
3.5.3.1 Treatment
Initial microbe treatment was 150 barrel of microbe-laden
water followed by a 48 hour shut-in on 2 wells and 24
hours on the other. Subsequent treatment have been 50
barrels every 15days on two of the wells and every 30days
on the other wells.
3.5.3.2 Evaluation
The project was on a 7.1% per year decline for 29 months
before MEOR was begun. For 14months since the start of
MEOR, the oil production rate has inclined at the rate of
7.3% 1 year. Water production has also increased after the start of MEOR. For the 14 months 19000 barrels of incremental oil has been produced which is 19% over the baseline. Oil production is 270bbls/day, 29% over baseline. The cumulative incremental increase is projected to be 57% by the end of the project life.
Oil in-place at the end of the project life would have been
509bbls/acre-ft versus 442bbls/acre-ft with MEOR.
Residual oil saturation is projected to decrease from 38.3%
under water flood to 33.3% with MEOR.
3.5.4 Huabet Project
This project contains 7 wells. The wells in the later stage of being water flooded, are scattered and not in the same reservoir. Therefore, while production data can be analyzed, reservoir performance cannot be determined for this grouping. MEOR started September of 1994.
The wells are rod pumped, with pumps set an average of
2,500 feet above perforations. Reservoir and fluid
parameters are all favorable for microbe growth.
3.5.4.1 Treatment
Each well was treated three times. The first 2 treatments
consisted of 150 barrels of microbe-laden flood, followed by
40-150 barrels of displacing water. The displacement was
calculated according to the distance the pump was set over
the perforations and the pumping floor level. The third
treatment was 50 barrels with displacements ranging from
40-125 barrels.
3.5.4.2 Evaluation
The wells in this project were on a rapid decline before
MEOR was begun. The baseline was determined from a
well by well review of daily production for the five months
before the start of MEOR. For 12 months after the start of
MEOR, oil production rate has inclined then flattened at
150 barrels per day. Water production decreased after the
start of MEOR. Water-cut decreased from over 70% to
fewer than 60% and the trend in water-cut versus
cumulative oil production which was rapidly increasing

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1383

ISSN 2229-5518

started decreasing. Over the 12 months, 41 barrels of incremental oil have been produced which is 216% over the baseline. Oil production is 150 barrels per days 552% over baseline.
3.5.5 Xinjiang Project
This project contains 10 wells located in the Xinjiang
Petroleum Administration Bureau. The wells, mostly in the
later Stage of being water flooded, are scattered and not in
the same reservoir. Therefore, while production data can be
analysed, reservoir performance cannot be determined for this grouping. MEOR treatment started in 1995.
The wells are rod pumped, with pumps set from 200 to as high no 6000 feet above the perforations on one will. Reservoirs and fluid properties/parameters are all
favourable for microbe growth.
3.5.5.1 Treatment
Each well was treated three times. The first treatments
consisted of 150 barrels of microbe-laden fluid on 7 wells
and 80 barrels on 3 well followed by 0-150 barrels of
displacing water. The displacement was calculated according to the distance the pump was set over the perforations and the pumping fluid level. The second and third treatments were 50 barrels in 6 wells and 75 barrels on
4 wells with displacement ranging from 0—70 barrels.
3.5.5.2 Evaluation
The wells in this project were on a rapid decline for 24 months before MEOR was begun. For six months after the start of MEOR the oil production rate increased then maintained a rate of 300bbl/day. Water production decreased after the start of MEOR and the water-cut decreased from 64% to 54%. The trend in water-cut versus cumulative oil production which was rapidly increasing became flat. Over 6 month 14,000 barrels of incremental oil was produced which is 43% over the baseline. The baseline sample indicated microbes could significantly alter the crude.
On five of the wells, the operator measured an average
decrease in viscosity at 680F from 273 to 184 cp (49%) and
an increase in gravity from 28.70 API to 29.60 API (3.1%).
Microbes favorably altered the oil in this reservoir.
3.6 FACTORS TO CONSIDER BEFORE APPLYING MEOR The application of enhanced oil recovery (EOR) technology is being applied worldwide, and can only be expected to increase due to the diminishing development of new fields and the decline of more mature one. MEOR processed address the same physical parameters as chemical enhanced oil recovery processes. Hence they are subject to the same technical difficulties.
3.6.1 Selecting the Reservoir
Reservoir selection for MEOR processes can prove to be a
challenging task. Candidate reservoir selection for MEOR
processes requires considerations of a number of parameters before it can be successfully implemented. In case of mature field, in-situ MEOR is mainly targeted towards the residual oil left after the primary production and secondary recovery methods.
The following are the common factors needed to be considered before we apply MEOR to a certain reservoir. These parameters can vary widely from reservoir to reservoir and in some cases novel parameters may also be considered before MEOR is implemented
3.6.1.1 Structural Analysis
Marginal resources mean a very little or no room for errors.
Structural analysis must be done in order to have an
optimized plan before injecting microbes into the
formation. A region of by-passed oil and areas as of high permeability to plug certain formation pores cannot be identified without structural analysis. Using a structural analysis approach, drilling uncertainties and risks could be identified. However, structural analysis could sometimes be an issue and if a structure is analyzed improperly, there is a fair chance that the microbes would act as a bad candidate. Initial water saturation, spatial distribution of oil lenses, spatial distribution of facies and faults representation are necessary things before adopting MEOR.
3.6.1.2 Geological Complexity
Geological complexity needs a thorough study because it
plays a vital role in microbes injection into the reservoirs
and the function they perform. Due to several reasons such
as changes in permeability, porosity, wettability, etc. the
microbes might not reach the target zone.
3.6.1.3 Well Pattern To Be Drilled
This parameter is again critical in injection and production
of hydrocarbons. Thus a detailed study needs to be
conducted before the injectors and producers are decided in
marginal reserves. For an optimized plan, selecting the
right pattern to be drilled is essential. Due to economic factors, if horizontal, directional, extended reach drilling is considered, then a proper pattern of injectors and producers must be studied for MEOR.
3.6.1.4 Permeability Analysis
This factor is necessary for selecting the strain of bacteria and to survival or feeding technique and composition.
3.6.1.5 Petro Physical Analysis
PVT and other petro-physical analyses are important so
that comparison after application of MEOR can be made
and other laboratory studies can be carried out.
3.6.1.6 Temperature
Temperature is a very important part and plays a very vital
role in MEOR. At high temperature bacterial growth and
their metabolic processes would be highly influenced in the
anaerobic nutrient-lack environment. Thus, the reservoir
temperature must suit microorganisms for their survival and growth. In high temperature reservoirs, the development of such microorganisms which can sustain and stimulate their growth can be a big challenge.
3.6.1.7 Can The Production Target Be Met?
Deciding whether the application of MEOR will help you in achieving the required production target is a function of many considerations. This can be done through, pilot testing and laboratory test in cores.

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1384

ISSN 2229-5518

There are many other factors which could/should be studied so that microorganism growth and stimulation could not be affected by formation. These are
Remaining oil saturation
Fluid evaluation: Hydrocarbon compositional analysis
Fluids chemistry and composition
Depth of reservoir
Salinity of formation water
Formation water sample analysis
Net oil increase: estimates
Economic aspects
3.6.2 Identifying the Chemicals That Need To Be
Produced And The Job They Need To Perform
There are several ways in which microorganism may
contribute to enhanced oil recovery. The next challenge is to identify what chemicals produced by the bacteria can lead to optimum recovery. This process is again linked with reservoir study and the nutrients fed to the bacteria. Parameters relating to transport, growth and metabolite production by microorganism in petroleum reservoirs needs vigorous research. Microbial transport studies must be performed under reservoirs conditions.
The following are the main types of chemicals and mechanism that microbes can perform. However the production of these substances and other mechanisms need
to be carefully designed and monitored. Produce surfactants
Reduce polymer
Selective plugging by bacteria
3.6.3 Selecting the Right Bacteria
In MEOR, microbe species selection is crucial. They have to fit the reservoir conditions and produce the required bio- products. Different strains of bacteria have different adaptability therefore selecting the bacteria based on reservoir conditions and fluid properties are essential. Reservoir ecosystem provides the basis for positive response from bacteria.
Pore colonization by bacteria and the consequent products
produced by bacteria needs spatial attention. Essentially,
the most suitable train of bacteria can only be determined
after careful laboratory analysis and tests on cores.
3.6.4 Selecting the Nutrients For Bacteria
The classical definition of microbial enhanced oil recovery
is to introduce a microorganism along with a food source to
effect a positive change in the recovery mechanism of an oil
reservoir. The products produced by the bacteria and their
survival are dependent on the nutrients fed to them.
To sustain and prolong the maximum level required of
bacterial count, an optimum concentration of nutrients and
the right type of nutrients is desired. In fact, microbes may
already exist in the reservoir just surviving at a very low
metabolic level waiting for the right condition in order to revitalize.
Nutrients selection can only be done after a detailed study and testing period. Testing for the right nutrient is carried out after a clearly chalked out plan incorporating all the
production considerations. Effect of pH and other trace
minerals are also of prime importance in selecting the nutrients.
3.6.5 Pilot Testing
Pilot testing is the deciding factor in the successful application of MEOR. The projects are generally conducted in phases. In the initial research and development phase, extensive laboratory tests and analysis are conducted to understand process mechanisms and identify important parameters. Generally different task include;
Screening of available microbe-nutrient system that are viable in reservoir conditions in terms of compatibility, competitiveness and ability to propagate in porous media. Investigation of likely process by-products and their effects on oil recovery and screening.
Screening candidate reservoir for MEOR application.
The methodology for designing and optimizing MEOR
field tests has yet to be established, however, different
results have indicated that there are some necessary
procedures that need to be followed for a successful pilot
testing of a project. In pilot testing, parameters such as oil production, test results on standard cores, well selection, , incremental reserves, distribution of nutrients throughout the reservoir, evidence of microbial proliferation of reservoir etc. require strict analysis
3.7 EXPERIMENTAL STUDY
At the experimental stage of MEOR, before ascertaining the viability of the MEOR process on a reservoir and proceeding for a pilot test, a host of parameters are analysed.
3.7.1 Materials
Materials, nutrients and supplements used in the microbial profile modification process are an important part of the evaluation. There are many source of nutrients such as sucrose, molasses, corn steep liquor, black liquor, soy bean whey, tapioca whey, etc. the combination of nutrients with nitrogen, phosphorus, minerals and proteins.
3.7.2 Microbes
Microbe selection is crucial for a successful MEOR project
result. For this purpose the best strategy would be to gather
a multidisciplinary team consisting of a microbiologist,
geologist and a petroleum engineer and chalk out a strategy of core testing and other tests using different strains of bacteria and then selecting the best strain on the basis of result comparison.
3.7.3 Nutrients
Microbes require for a growth source of the major elements
which make up cell material-carbon, nitrogen, phosphorus, oxygen, sulphur, minor components such as iron, zinc, manganese, and a source of energy for the synthesis process involved in growth. In the laboratory, bacteria can be fed with different nutrients and the resultant by-product analysed. The nutrients giving the best by-products and acting in the desired way on oil should be chosen. Water is usually the preferred medium of choice. However medium properties and the formation to interact with should also be studied.
3.7.4 Water

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1385

ISSN 2229-5518

Testing formation for salinity, trace minerals and all other mineral dissolved in it as incorporated as part of the experimentation. Formation water testing reveals a great deal on the ability of the microorganism to survive in the formation and reproduce at the required rate.
3.7.5 Testing
Testing of MEOR projects to give a formal go ahead for
MEOR application in a various field include the following
slips.
Site selection
Sampling and analysis of well fluids
Selection of microbial formulation and compatibility test
Reductions follow up
3.8 MATHEMATICAL MODELING FOR MEOR
The current need for maximizing oil recovery from reservoirs has prompted the evaluation of various Improved Oil Recovery (IOR) methods and EOR techniques including the use of microbial processes. MEOR is a driving force behind the efforts to come up with different and cost effective recovery processes (Kianipey and Donaldson,
1986)30. Bryant and Lockhart (2002)31 examined the
qualitative correlations between microbial activity,
reservoir features and operating conditions such as
injection rates, well spacing and residual oil saturation.
Marshall (2008)32 stated that a mathematical model could
be used to recognize the most important parameters and their practical relationships for the application of MEOR. Improvement of detailed mathematical models for MEOR is an exceptionally demanding task. Not only as a consequence of the natural difficulty of the microbes but also because of the diversity of physical and chemical for the production of a given metabolite, but the rate of production can only be determine experimentally, and must be given by actual bacterial growth velocities (Marshall, 2008)32.
Several mathematical models were developed to simulate MEOR processes. The models usually included multidimensional flow of the multiphase fluid consisting of water and oil in process media along with specific equations for adoration and diffusion of maternities’, microorganisms, and nutrients (Islam, 1990)33 and (Behehst et.al. 2008)11. The main multidimensional transport equations were combined with equations of different microbial features such as growth, death and nutrient consumption.
Several assumptions are made for the transport equation
for the microbial process. Nielson et al (2010)12 points out the following assumptions
Fluid flow was one dimensional
The microorganisms were anaerobic bacteria and they were
injected into the reservoir. It was assumed that there was no
local microorganism in the reservoir.
Bacteria growth could be explained by monod-kinetics
being independent of temperature, pressure, pH and
salinity (Nielson et. al., 2010)12.
The major metabolite was surfactant and other possible
metabolites were considered insignificant.
variables that control their activities in subsurface porous media. Specific or general aims can be foreseen for modeling by researchers. In specific cases, it is desired to employ the models to maximize the yield and minimize the costs of the MEOR procedure. Main physical insight of the process can be obtained from quite simple analytical models, whereas the exact models regularly requires thorough numerical computation. The important point claimed by researcher is that modeling of microbial reactions still faces strict limitation. Models are based on the relation between the residues time (τres) of the bacteria on a cylindrical reaction zone of reactions; rm, depth to and
porosity, ϕ which is combined in relation as:

∆�rm h ϕ (1−S )

τres = or

Q
Where Q is the volumetric flow rate and Sor is the residual
oil saturation and the time required for the microbial
reaction to produce a desired concentration Creq for some
metabolite.
To estimate the reaction time, Marshall (2008)32 posed the
following assumptions:
Isothermal plug flow through the reactor,
Nutrient consumption is first order and irreversible, and
Nutrients initial concentration is no
The physical model on which the above argument is based is very basic, but the analysis draws interest to the important issue of reaction kinetics that has to be addressed by more complex treatments. It is possible to write a balanced chemical equation
Surfactants could be distributed between both phases (water and oil). Surfactant sharing was instantaneous and the distortion kinetics was neglected.
No substrate and metabolite adsorption on pore walls. Adsorption in any component was neglected.
Partial flow function was exploited, because capillary
pressure was considered negligible.
Negligible diffusion and chemotaxis.
Isothermal method with incompressible flow.
No volume change on mixing
3.9 LABORATORY STUDIES OF MEOR
As a result of the relative rarity of field MEOR applications,
most of the MEOR literature consist of laboratory,
theoretical and simulation studies. It is convenient to group
those studies as follows:
Microbial science (No attempt to recover oil) EOR (Attempt to recover oil)
Theory and simulation
3.9.1 Microbial Science
The laboratory studies grouped under microbial science
investigate the transport, growth are reaction of bacteria in porous media the major questions addressed under microbial science is summarized as: how far can this microbe be transported and under what conditions (Temperature pressure, nutrient supply etc.), does this microbe remain viable. Following the trend of studies in

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1386

ISSN 2229-5518

chemical EOR, more recent studies have focused on the reduction of permeability associated with in situ microbe growth. Quantitative data regarding the rate of biological reaction, the yield of the reaction (Mass of the desired product per unit substrate consumed) and the concentrates of reaction products are rarely given. Yet these parameters are absolutely fundamental in evaluating field application of this technology. The absence of a reservoir engineering perspective in the design and reporting of many experiments severely limits their practical utility. The identification of a mechanism for cell attachment and consequent control of microbe trapping in a porous medium constitute a rare exception (Lappan and Fogler,
1992, 1994)34, 35.
3.9.2 EOR
The laboratory study grouped under EOR follow
essentially the same procedure no those grouped under
microbial science but one carried not in the presence of oil.
Quantitative measures of reaction rates and yield are not
common, and relationship between these data and incremental oil production are almost never explored (e.g. how oil recovery depends on shut-in time after nutrient injections or on nutrient flow rate through the porous medium). A noteworthy step in this direction computes microbe/nutrient stoichiometry observed in a core flood and attempt to scale this in the reservoir (Sunde et. al.
1992)47. This is instructive for estimating volumes and
capacities and hence feasibility, but the critical element of
kinetics was not considered. The rate at which the microbial
reaction proceeds determines achievable product
concentrations and hence the efficiency of the process, and this is independent of stoichiometry.
Exceptional recoveries in the range of 30-60% have been reported, (Bryant and Douglas, 1998)36 (Almalik and Desouky 1996)37 though analysis of the data presented
indicate, that these values may include the effect of an increase in pressure during displacement. At the other extreme, the most carefully analysed series of MEOR care floods reported in the literature shored no recovery of residual oil of all (Rouse et. al., 1992)38.
The small amounts of oil recovered in laboratory MEOR and stretches after accommodate gradually during tens of PV of fluid injection after the microbial treatment. In contrasts theory for surfactant EOR process predicts formation of an oil bank (a small volume of high oil saturation), and such banks are observed in experiments for EOR process that reduces interfacial tension. These observations suggest that insufficient chemicals are being produced by the microbes. From a reservoir engineering perspective there is a clear need to investigate the concentration and transport of these in situ generated chemical to determine their efficacy for oil displacement as a function of concentration and to establish the mechanism for oil displacement. Given the wide gap between field and laboratory oil recoveries for chemical EOR processes and given that MEOR involves the same mechanist as EOR, the modest lab recoveries reported to date suggest that field
applications of MEOR would yield marginal recoveries at best. This is borne out by the field trials of MEOR reported to date. Failure to achieve high recoveries with a far PV of injected nutrients in the laboratory, and to recognise this as a key issue is emblematic of the distance that separates the current state-of-the-art from the ultimate objectives of MEOR research.
3.9.3 Theory And Simulation
The study (ies) grouped under theory and simulation
either present overviews of EOR and MEOR characteristics or models for simulation of some aspects of MEOR. An important message from the former is that MEOR is not a panacea, if a reservoir is not good candidate for MEOR. This conclusion is to be expected since MEOR relies on the same recovery mechanisms as traditional EOR while introducing the additional difficulty of establishing viable microbe colonies in the reservoir. The lack of quantitative reaction data has severely hindered the useful application of simulators.
DISCUSSION
Microbial recovery processes is another tertiary method of
oil recovery commonly known as MEOR, which nowadays
is becoming an important and rapidly development tertiary
production technology, which uses microorganisms or their
metabolites to enhance the recovery of residential oil
(Banat, 1995)39, (Xu et. al., 2009)40.
In this method, nutrients and suitable bacteria which can
grow under the anaerobic reservoir conditions are injected
into the reservoir. The microbial metabolic products that
include bio-surfactant, biopolymers, acids, solvents, gases
and also enzymes modify the properties of the oil and the interaction between oil, water and the porous media which increase the mobility of the oil and consequently the recovery of oil especially from depleted and marginal reservoirs. In some process, a fermentable carbohydrate including molasses is utilized as nutrient (Bass and Lappin- Scott, 1997)41. Some other reservoirs require inorganic nutrients as substrates for cellular growth or as alternative electron acceptor instead of oxygen. In another method, water containing a source of vitamin phosphates, and election acceptors such as nitrate is injected into the reservoirs, so that anaerobic bacteria can grow using oil as the main carbon source (Sen. 2008)4. The microorganisms used in MEOR methods are mostly anaerobic extremophiles, including halophiles, barophiles and thermophiles for their better adaptation to the oil reservoirs conditions (Brown, 1992)21 (Klire and Khan, 1994)42 (Bryant and Lindsey, 1996)43 (Tango and Islam, 2002)44. The bacteria are usually hydrocarbon-utilising, non- pathogenic, and are naturally occurring in petroleum reservoirs (Almeida et. al. 2004)45.
In the past, the microbes selected for uses, had to have a maximum growth rate at temperature below 800C, however it is known that some microorganisms, can actually grow at temperature up to 1210C. Baccillus strain grown in glucose mineral salts medium are one of the most utilised bacteria in MEOR technologies, specifically when

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1387

ISSN 2229-5518

oil viscosity reduction is not the primary aim of the operation (Sen. 2008)4.
The application of MEOR as a tertiary recovery techniques and a natural step be decrease residual oil saturation has been report (Bahesht et. al., 2008)11. A complete review of the microbiology of petroleum was published by Vam Hamme et. al., (2005)46, which covered a significant amount of literature. The publication is mainly focused on the description of the Molecular biological characteristics of the aerobic and anaerobic hydrocarbon exploitation, with some citation in the application of the microbe, microbial oil recovery, and biosensors. The aspect of petroleum microbiology that is perhaps the most important for MEOR is the ability of the microbes to use hydrocarbons as the carbon and energy sources.
Biotechnology research has improve, which has influenced
the oil industry to be more open to the evaluation of
microorganisms to enhance oil production. Both
indigenous and injected microorganisms are used
depending on the adaptability to the specific reservoir. In microbial enhanced oil recovery (MEOR) bacteria are regularly used because they show several practical features (Nielson et. al., 2010)12. Several publications state that oil through microbial action takes place due to several mechanisms as follows:
Reduction of oil/water interfacial tension and modification of porous media wettability by surfactant production and bacterial action.
Selective plugging of porous media by microorganisms and their metabolites.
Oil viscosity reduction caused by gas solution in the oil due to bacterial gas production or degradation of long chain saturated hydrocarbons.
Production of acids that dissolve rock thus improving porous media permeability.
The first two mechanisms are believed to have the greatest effect on improving oil recovery. (Nielson et. al., 2010)12 (Desouky et. al., 1996)37 (Bryant, 1989)7.
Lazar (2007)3 points out some outstanding advantages of microbial enhanced oil recovery over other enhanced
recovery techniques such that the injected bacteria and its nutrients are inexpensive and easy to obtain and handle in the field. MEOR is also economically attractive for marginally producing oil fields and are suitable alternatives before the abandonment of marginal wells. Most importantly, as Lazar (2007)3 observed is that the effect of bacterial activity within the reservoir are improved by their growth with time, while in other EOR technologies, the effect of the additives tend to decrease with time and distance from the injection well.
MEOR is not without some challenges and problems. Lazar
(2007)3 points some of the challenges as injectivity loss due to microbial plugging of the wellbore-to avoid wellbore plugging, some actions must be taken such as filtration before injection to avoid polymer production and minimize microbial adsorption to rock surface by using dormant cells forms, spores, or ultra-micro-bacteria. Sen (2008)4 also
points out that the isolation of microbial strains, adaptable to the extreme reservoir conditions of pH, temperatures, pressure and salinity is a big challenge.
CONCLUSION
In conclusion, it is observed that
MEOR is a well proven technology to enhance oil recovery
especially in mature oil wells.
MEOR is a cost effective and ecofriendly process that shows
several advantages over other EOR processes.
MEOR has a great potential to become a viable alternative to the conventional EOR chemical method.
In spite of the various advantages of MEOR over other EOR methods, it has gain little credibility in the oil industry because the value of MEOR is mostly determined by the
result of field trials.
Most MEOR literature is based on laboratory data and a
shortage of ample field trials can be seen.
Moses (1991)15 pointed out that the follow up time of most
field trials was not long enough to determine the long-term
effect of the process.
Although MEOR is a highly attractive method in the field
of oil recovery, there are still uncertainties in meeting the
engineering design criteria required by the application of
microbial processes in the field.
Optimisation of nutrients and testing the microbes and
their byproduct compatible with reservoir conditions are required.
RECOMMENDATION
After the review, it is recommended that
More research should be conducted on MEOR to cover for
the uncertainties in the Engineering design.
Toxicity test is recommended on the microbe that are to be
used in the field to assure that it is safe to handle and pose
no threat to humans or to the environment.
A wide range compatibility test is required of the nutrients,
microbe and their by-product with the reservoir and the prevailing conditions.
Compatibility test should be widely conducted between indigeneous and injected microbes.
Interdisciplinary research and collaboration is highly
recommended between Petroleum Engineers, Microbiologists, and Geologist.
REFERENCE
Sarkar, A.K., Goursaud, J.C., Sharma, M.M., In situ. 1989,
13:207-238
Zahid, S., et.al., SPE 108726 (2007) paper presented at IOCE Mexico, 27-30 June
Lazar, I., Petrisor, I.G., and Yen, I.F. (2007). Microbial enhanced oil recovery (MEOR). Petrol. SciTechnol. Vol.25, No.11, pp.(1353-1366)
Sen, R. “Biotechnology in petroleum recovery.” The MEOR Prog. Energy Comb. Sci. 2008 vol. 34 pp 714-724
Behlulgil, K., Mehmetoglu, M., “Bacteria for the improvement of oil recovery.” Energy sources 2003, vol. 25 pp 871-877

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1388

ISSN 2229-5518

Youssef N. H., Duncan, K.E., McInerney, M.J., “In situ bio- surfactanta production by Bacillus strains injected into a limestone petroleum reservoir” Appl Environ Microbial,
2005 vol. 71 pp 7690-7695
Bryant, R.S., “Review of microbial technology for
improving oil recovery” (1989) SPE Reservoir Engineering,
151-154
Maudgalya, S., Knapp, R.M., McInerney, M.J.,
“Biosuractants and their role in oil recovery” (2007) SPE
106978.
ZoBell, Claude, E., “Bacterial release of oil from
sedimentary materials” oil and gas 1. (Aug. 2, 1947) 62-65
Yarbrough, H.F., and Coty, F.V. (1983) Microbially
Enhancement Oil Recovery from the upper cretaceous
Nacafoch formation union county, Arkansas proceedings of
1982 international conference on MEOR, Donaldson, E.C.,
and Benette Clark, J.B.(Eds), Afton, Oklahoma, pp(149-153)
Behesht, M., Roostaazad, R., Farhadpour, F., and Pishvaci,
M.R.,(2008) model development for MEOR process in
conventional non-fractured reservoirs and investigation of physio-chemical parmeters effects. Chem. Eng. Technol.vol.7, pp953-963
Nielson, S.M., Sharpiro, A.A., Michelson, M.L., and Stenby, E.H., (2010) 1D simulation for microbial enhanced oil recovery with metabolite partitioning Transp. Porous med.,
vol. 85, pp785-802
Jack, T.R., and Steheier, G.L., (1988) symposium on
application of microorganisms to petroleum technology
McInerney, M.J., Sublette, K.L. Manual Environ. Microbiol.
2002 vol. 2 pp 777-787.
Bass,C., (1997) Oilfield Rev. vol. 9 pp17-25
Brown, F.G. SPE oil and Gas Recovery conference, 1992,
SPE 23955.
Hitzman, D.O., and Sperl, G.T., (1994) SPE/DOE ninth
symp. On improved oil recovery; SPE/DOE 27752
Pommerville, J., Aleamo’s laboratory Fundamentals of Microbiology, 7th ed., Jones and Bartlett publishers, 2005. Lazar, I. “Preliminary results of some recent MEOR field trials” Devel Petr. Sc, 1991, vol. 33 pp 365-386
Rodriguez, L.R., Teixeira, J.A., Oliveira, R. Biochem. Eng.
Journal 2006, vol. 32 pp 135-142
McInerney, M.J., Sublette, K.L., Manual Environ. Microbiol.
2002. 2:777-787
Brown, F.G., SPE oil and gas recovery conference, 1992, SPE
23955
Akit, R.J., Cooper, D.G., Neufield, R.J. Geomicrobial Journal
1989 vol. 7 pp 115-165.
Youssef N. H., Duncan, K.E., McInerney, M.J., Appl
Environ Microbial, 2005 vol. 71 pp 7690-7695
McInerney, M.J., Nagle, D.P., Knapp, R.M., Petroleum
microbiology 2005, vol. 11 pp 215-237.
McInerney, M.J., Javaheri, M., Nagle, D.P., journal of I. microbial, 1990, vol. 5 pp 95-102
Gray, M.R., Yeung, A., Foght, J.M., “Potential microbial enhanced recovery processes: A critical analysis” Annual technical conf. 2008 SPE 114676
Ramsay, J., phD thesis McGill university Montreal, Canada,
1987
Ramkrishna, S. (2008) Biotechnology in petroleum recovery.
The microbial EOR-Prog. Energy comb. Sci. vol.34 pp 714-
724
Dietrich, F.L., Brown, F.G., Zhou, Z.H., Maure, M.A., “An
(1996) SPE 36746
Kianipey, S.A., and Donaldson, E.C., (1986) 61st Annual
technical conference and exhibition, New Orleans LA
Bryant, SL., and Lockhart TO., (2002) Reservoir Engineering of Microbial Enhanced Recovery (SPE 79179) SPE Res. Eng. Eval. Pp 365-374
Marshall, S.L., (2008) “Fundamental aspects of microbial enhanced oil recovery”: A literature survey, CSIRO land
and water floreat, western Australia, pp 1-42
Islam, M., (1990) “Mathematical modeling of microbial
enhanced oil recovery”.
Lappan, R., and H., Fogler “Effect of bacterial
polysaccharide production on formation damage” SPEPE
(May) 167-171, 1992
Lappan, R., and H., Fogler “Leuconostoc mesenteroids
growth kinetics with application to bacterial profile
modification” Biotechnology and Bioengineering, 43:
Bryant, R., and J. Douglas,: Evaluation of microbial system
in porous media for EOR, SPERE 3 (may), 489-495, 1998
Almalik, M., and G. Desouky “Saudis study native bacteria for MEOR”, Harts Pet. Eng. Intl. (June), 46-73, 1996
Rouse, B., F. Hiebert and L. Lake: “Laboratory testing of a microbial enhanced oil recovery process under anaerobic conditions,” SPE 24819 presented at SPE Ann. Tech. Conf.
Exhib., Washington, DC, 4-7 Oct., 1992
Banat, I.M., (1995) Bio-surfactants production and possible
uses in microbial enhanced oil recovery and oil pollution
remediation: A review Biores. Technol. Vol. 51, pp 1-12
Xu, T., Chen, C., Liu, C., Zhang, S., Wu, Y., and Zhang, P.,
(2009) “A novel way to enhance the oil recovery ratio by streptoccus Sp. BT-003. J. Basic microbial., vol. 49, pp 477-
481
Bass, C., and Lappin-scott, H., (1997). The bad guys and the
good guys in petroleum microbiology. Oilfield Rev., pp 17-
25
Khire, J.M., and Khan, M.I., (1994) Microbially Enhanced
Oil Recovery (MEOR) PART 2: microbes and subsurface
environment for MEOR. Enz. Microb. Technol. Vol. 16, pp
258-259
Bryant, S.R., and Lindsay, R.P., (1996). Worldwide
application of microbial tehnology for improving oil recovery. SPE J, paper No. 35356
Tango, M.S.A., and Islam, M.R. (2002). Potential of extremophiles for biotechnological and petroleum applications. Energy sources, vol. 24. Pp 543-559
Almeida, P.F., Moriera, R.S., Almeida, R.C.C., et. al., “Selection and application of microorganisms to improve oil recovery. Eng. Life sci., vol. 4. Pp319-325
Van Hamme, J., Singh, A. et.al., “ Physiological aspects
(microbiology and biotechnology) ” Energy sources 2005,
24:52-56

IJSER © 2015 http://www.ijser.org

International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1389

ISSN 2229-5518

Sunde, E., J. Beeder, R. Nilsen and T. Torsvik, Aerobic microbial enhanced oil recovery for offshore use, SPE 24204
presented at SPE/DOE 8th Symp. Enhanced oil recovery, Tulsa 22-24 Apr. 1992
Omoniyi,O.A. works as a Lecturer with the Department of Petroleum Engineering Abubakar Tafawa Balewa,University Bauchi, Bauchi State, Nigeria,

IJSER © 2015 http://www.ijser.org