Table Of ContentTheory and Practice in
Microbial Enhanced
Oil Recovery
KUN SANG LEE
Professor
Hanyang University
South Korea
TAE-HYUK KWON
Associate Professor
Korea Advanced Institute of Science of Technology
South Korea
TAEHYUNG PARK
Postdoctoral Researcher
Korea Advanced Institute of Science and Technology
South Korea
MOON SIK JEONG
Postdoctoral Researcher
Hanyang University
South Korea
]
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Preface
As oil and gas price fluctuates with global economy, practical applications related to MEOR, complemen-
developmentofcost-effectivetechnologies,whichyields tary to several literature and books published in the
themaximumoilrecovery,isofmaininterestintoday’s pastdecades.
petroleum researches. Microbial enhanced oil recovery Chapter 1 serves as an introduction to the overall
(MEOR) has a strong potential as low-cost techniques strategy of the MEOR method and the subsurface
with less impact to environment, in which different environment affecting the process efficiency. It also
microorganisms and their metabolic products are presents the screening criteria of the reservoir for the
implementedtoincreaseproductionrateandefficiency successful applications of MEOR. Chapter 2 reviews
inhydrocarbonreservoirs.Despitedrasticadvantagesof the microbial communities in deep subsurface asso-
MEOR technology, the technique still remains poorly ciatedwithoilreservoirsandaddressesvariousMEOR-
supported due to lack of knowledge on microbial ac- related microbial products and their characteristics.
tivitiesandcomplexityoftheassociatedprocesses.Some Chapter 3 provides fundamental pore-scale mecha-
oftheMEOR-relatedstrategieshavedemonstratedtheir nisms of microbial activities and their effect on oil
feasibility on a mass scale through both lab and field production in porous media at a core scale. This
trials; however, much workstill remains to implement chapteralsocompliesextensivelaboratoryexperiment
MEORintooilindustrypractices. data that are relevant to MEOR processes. Chapter 4
The authors review and summarize engineering describes numerical simulation of MEOR processes
fundamentals of MEOR with emphasis on microbial including selective plugging, microbial surfactant
mechanisms and reservoir-scale modeling. This book generation,andothermechanismsofbacteria.Chapter
provides comprehensive description on fundamental 5 presents considerations and practical examples on
andcriticalaspectsofMEORandestablishesthecred- the field applications of MEOR in terms of lithology,
itability of field applications. Newest experimental type of application, recovery mechanisms, and used
measurements and observations on MEOR-related microorganisms.
mechanismsaswellasrecentdevelopmentinnumer- Thisbookwouldneverhavebeenpublishedwithout
icalassessmentofMEORapplicationscanbeofinterest theableassistanceofElsevierstaffsfortheirpatienceand
for the main audience. The main audience would be excellenteditingjob.Weshallappreciateanycomments
theenhancedoilrecovery(EOR)(R&D,reservoirand andsuggestions.
operational) community, potentially geologists and
bio-/microbialgeologists,andreservoirmodelers.This KunSangLee
bookalsoupdatesthecurrentprogressinresearchand Seoul,Korea
v
Nomenclatures
A c optimum NaClconcentrationfor
NaClopt
A constantinEqs4.65and4.85 bacterial metabolism
A initialsurfacearea c biopolymer concentration
0 poly
A cross-sectional area c UAPconcentrations
cs UAP
A empiricalparameter inEq4.93 c concentrationoftheinsolubleproducts
H s
A average cross-sectional area along a
ave
breakthroughchannel D
A cumulative wall surface area along a d plate thickness
cum p
breakthroughchannel D decimalreduction time
A constantinEqs4.23and4.24 D initialdiameter ofporethroat
j 0
Ajþ1 constantinEq4.24 D1 changeddiameter ofporethroat
a activityofthe activeenzyme D diameter ofnetworkbond
bond
a innerradius D decimaltimeat ithpressure
i i
a initialradius D equatorial diameterinthedrop
ini E
a radius of the water-filled pore space
r
(reducedradius) E
a pore radius with biopolymer satura- E enzyme
w
tionS E activationenergy
BP a
a poreradius withnobiopolymer E total numberofenzymes
wo tot
ad adsorbedmolesofbioproducts
ad maximumadsorptioncapacity F
max
F constant inEq4.21
B F formation factorinafully
0
B constantinEqs4.16,4.65,and4.84 water-saturated rock
B empiricalparameter inEq4.93 F constant inEq4.22
H 1
b endogenousdecaycoefficient F constant inEq4.22
2
b constantinEq4.31 F capillary force
1 c
F electrical formation factorinEq3.25
e
C F viscousforce
v
C constantinEq4.65 F force required to raise the ring from
max
C empiricalgeometrical constant theliquid’ssurface
g
C empiricalconstant f flow-efficiency coefficient
H
C volume fraction of component i in f fractionoftheactivebiomasswhichis
ij d
phasej biodegradable
C parameter used to fit the laboratory f correction factor
p c
measurements
CK Carman-Kozenyconstant G
c constantinEq4.31 G freeenergy
1
c regressioncoefficient g geothermal gradient((cid:2)F/100ft)
2 G
c regressioncoefficient g gravitational force
3
c attachedcellconcentration
att
c BAPconcentrations H
BAP
c NaClconcentration H fittingparameter
NaCl
c maximum NaCl concentration for H shape-dependent constant
NaClmax c
bacterialmetabolism h height ofraisedwater
vii
viii NOMENCLATURES
I M
I salinityinhibition constant m microemulsion phaseorcomponent
S
(cid:3)
I constantdepending onthecultures m empirical tortuosityfactor
S g
m massofbacterial cell
cell
K
K concentration giving one-half the N
maximumrate N number of surviving microbes after
K baselinepermeability pressuretreatment
0
K absolutepermeability N number of capillaries per unit cross-
a a
K half-maximum rate concentration of sectional area
A
thesecondsubstrate N capillary number
c
K half-maximumrateconcentrationsfor ðN Þ critical capillarynumber
BAP c c
BAP ðN Þ maximum desaturation capillary
c max
K Michaelis-Mentenconstant number
M
K half-maximumrateconcentrationsfor N initialnumberof microbes
UAP o
UAP N numberof capillarytubes
t
K substrateinhibition constant n constant in Eqs 3.34, 4.42, 4.43, and
i
KðS Þ permeability with biopolymer 4.85
BP
saturation n Archiesaturationexponent
A
Kp=s saturation constant for metabolite to n' constant inEq4.47
consumptionofsubstrate S n exponent ofphasep
p
K relativepermeability reduction ratio
r
K normalizedpermeability O
N
k first-order rateconstant o oilphaseorcomponent
k dissociationconstants forE
1
(cid:4)
k dissociationconstants forE P
2
k rate constant for association P product
3
ðEþS/ESÞ P pressure(absolute)
a
kq rateconstantwhen ½Naþ(cid:5) ¼ 1M pH maximumpHfor microbialgrowth
3 max
k rate constant for dissociation pH minimumpHfor microbialgrowth
4 min
ðEþS )ESÞ p capillary pressure
c
kq rateconstantwhen ½Naþ(cid:5) ¼ 1M p displacement pressure
4 d
k rate constant for chemistry step p pressureatithstep
5 i
ðES/EPÞ Dp maximumpressuredrop
max
k effectivepermeability
e
k changedpermeability Q
f
k permeability multiplier factor Q flowratesfor influentandeffluent
mul
k originalpermeability bq maximum specific rate of substrate
o
k relativepermeability ofphase p utilization
rp
ke end-point relative permeability of bq maximum specific rates of BAP
rp BAP
phasepatitsmaximum saturation degradations
bq maximumspecificratesofUAPdegra-
UAP
L dations
L ratioofthespecificgrowthrateatthe
beginning of the deceleration state to R
previousexponential stage R gasconstant (cid:2) (cid:3)
L lengthofactualflow R solubilization ratio cosurf
a os (cid:2)csurf (cid:3)
L lengthofcore
c R solubilization ratio cwsurf
Ls lengthofsample ws csurf
r growthrate
l lengthofporethroat
r radiusof capillarytube
l lengthofnetwork c
network
rrft constant forresidualresistance factor
NOMENCLATURES ix
r production rateofBAP U
BAP
r production rateofUAP u Darcyvelocityofthe displacingfluid
UAP
rdeg(cid:4)BAP degradationrates ofBAP 4u interstitial velocity
r degradationrate ofUAP
BAP
r valueof r atthisphysicallimit V
lim
r maximum specific rate of metabolite V volumeofchemostat
max
production V initialvolume
0
r netgrowthrate forbacteria V volume of bulk volume of the reser-
net bulk
r production rate voirrock
p
r averageoftheinnerandouterradiiof V volumeoffluid inthe reservoirrock
r fluid
thering V volumeofentirepores
pore
r rateofsubstrate utilization V volumeofthesolid grains
ut solid
V volumeofbiofilm
biofilm
S ðV Þ fractional bulk volume occupied by
S concentration of the rate-limiting b pc the displacing fluid at any capillary
substrate pressure
S fluid saturation ðV Þ fractional bulk volume occupied by
Sf hydratesaturation b pN thedisplacingfluidatinfinitepressure
hydrate
S normalizedsaturation V surfactant volume in the microemul-
p sm
(cid:3)
S critical concentration of the substrate sionphase
formetabolicproduction v pore flow velocity of the displacing
S' concentrationofthesecondsubstrate fluid
S gassaturation
g
S oilsaturation W
o
S saturationofphasep w waterphaseorcomponent
p
S specificsurface areaperunit volume w widthof plate
sv p
S watersaturation
w
S irreducible or residual saturation of X
pr
phasep X initialbiomass
0
S residualsaturationoftheotherphase X bacterial concentrationattime t
p'r A a
S biopolymersaturation X concentrationof activebiomass
BP a
S normalizedresidual saturation X concentrationof bioproducts
pr b
surf surfactant X inertbiomassconcentration
i
X maximum possible microbial
max
T biomass
T temperature
T conceptual temperature of no meta- Y
0
bolicsignificance Y yieldcoefficient
T formationtemperature((cid:2)F)
f
T maximum temperature for microbial Z
max
growth z negative reciprocal slope of the logD
p
T minimum temperature for microbial vs.p
min
growth
T optimum temperature for bacterial GreekSymbols
opt
growth a lineargrowth rate
T meansurface temperature((cid:2)F) a BAPformationcoefficient
s BAP
t time a UAPformation coefficient
UAP
t time at the transition from exponen- a destruction rateconstant
a d
tialtothe decelerationstage b constant of proportionality between
t hydraulicdetention time thermodynamic changes and kinetic
d
changesdueto½Naþ(cid:5)
x NOMENCLATURES
d constantinEq4.84 r densityoffluid
ε constantinEq4.85 r densityofair
a
f porosity r densityofwater
w
f changedporosity r biofilmdensity
f biofilm
f originalporosity r densityofinsoluble products
o s
4o ðVwmVþomVomÞ ss imntaexrifmacuiaml tenIFsTionfrom experimental
4w ðVwmVþwmVomÞ max measurements
g constantinEq4.18 s minimum IFT from experimental
min
gwa surfacetensionbetweenwaterandair measurements
mb maximumspecificgrowth rate sðc Þ IFTatagivensurfactantconcentration
surf
mbp maximumspecificproduction rate s tortuosity
m netspecific growthrate s Binghamyield stress
B
mf visocistyof fluid ss shearstress
mdisplacing displacingfluid viscosity u constant inEq4.25
mdec specificgrowth rateduetodecay uv angularvelocity
mopt specific growth rate at the optimum q contactangle
conditions q shapefactor inEq3.23
sf
m specificgrowth rateforcellsynthesis
syn
CHAPTER 1
Introduction
1.1 MICROBIAL PROCESSESFOROIL the general case. Since the ex situ MEOR process faces
RECOVERY many problems, it must overcome these hurdles to
1.1.1 StrategyOverview establish itselfasawidespread industrypractice (Patel
The microbial enhanced oil recovery (MEOR) is not a etal.,2015).
completely new concept. In 1926, Beckman introduced Incontrast withtheexsituprocess,theinsitupro-
that microorganisms can be used to release oil from cess stimulates the indigenous microorganisms in the
porous media (Lazar et al., 2007). Since then, Zobell reservoir to generate the desired metabolites. While
(1947)hasutilizedsulfate-reducingbacteriainenhanced the ex situ process yields predictable results with
oil recovery. Recent MEOR researches have predomi- controlledlaboratorysettings,theresultsoftheinsitu
nantlyfocusedonexsituandinsitumethodstotransport process have considerable uncertainty depending on
the metabolites into oil wells as well as on the funda- the field application. Indigenous bacteria of interest
mental challenges of oil production, which include the arestimulatedwithinjectedsubstratestogenerateand
immiscibility of oil in water, the high viscosity of the release bioproducts such as biopolymers, bio-
oil,andthesizeofoilcomponents(Pateletal.,2015). surfactants, bioacids, and biosolvents (Fig. 1.1). The
The ex situ method is similar to the chemical biofilm production to decrease the pore volume is
enhanced oil recovery (CEOR) approach. In this also applied in MEOR process. Although both ex situ
method, the desired bioproducts are produced exter- andinsitumethodsarepotentialandapplicablesimul-
nally and then injected into the wellhead to improve taneously, the available literatures indicate thatinsitu
oil recovery. Because the specific composition, com- methodismoreimportanttechnologyintheoilindus-
pounds, and products can be selected and injected, try (Sen, 2008; Bao et al., 2009; Gudiña et al., 2012;
such a method is attractive in that direct control is Youssefetal.,2013).
possible by reservoir operators. The microbes used in In addition to the reservoir environments that may
the ex situ MEOR processes are either grown or engi- affect bacterial growth such as pH, temperature, and
neered in the laboratories to improve sweep and/or pressure,manyotherchallengesremainresearchtopics
displacementefficiency.Targetbioproductssuchasbio- forMEORapplications.Forexample,auniquecharac-
surfactantscanbeextractedfromthesemicroorganisms teristic of microorganisms that must be considered in
and mixed with water before injection, sometimes in MEOR applications is that they can be grown in an
combination with synthetic chemicals. In other ap- anaerobic environment. Most reservoir conditions are
proaches, the isolated bacteria may be injected into oxygendeficient,andinjectingoxygentogrowmicrobes
the well, with the hope that they will generate the can cause metal corrosion and equipment damage.
desired metabolites within the reservoir (Patel et al., Injectingoxygen,asanelectronacceptor,canalsocause
2015). imbalances in the microbial environment and lead to
Although the ex situ method seems to be quite target microbes being outcompeted by other indige-
feasible, numerous concerns exist. First of all, the cost nous bacteria (Bryant, 1990; Lazar et al., 2007). These
of producing ex situ bioproducts is significantly high. reservoirenvironmentsandbacterialgrowthcharacter-
Whileusingthecrudeformsofbioproductscangreatly isticsconstitutethebasicparametersofMEORapplica-
reducetheprice,thehighcostofexsituprocessstillre- tions. Employed microorganisms and bioproducts
mainsalargeconcernfortheadvanceofpetroleumin- mustberesistanttothereservoirenvironmentsandbe
dustry(Pornsunthorntaweeetal.,2008(b);Zhengetal., activation in those conditions. As each well has its
2012). Furthermore, microbes, modified in laboratory own unique environment, a variety of microbial con-
and directly injected, are expected to outcompete the sortiums andmixed bioproducts must be usedfor the
reservoir indigenous microbes already adapted to the success of MEOR application (Lal et al., 2005; Wang
harsh environments. However, this expectation is not etal.,2007;Sen,2008;Darvishietal.,2011).
TheoryandPracticeinMicrobialEnhancedOilRecovery.https://doi.org/10.1016/B978-0-12-819983-1.00001-6
Copyright©2020ElsevierInc.Allrightsreserved. 1
2 TheoryandPracticeinMicrobialEnhancedOilRecovery
FIG.1.1 InsituMEORprocesses:(A)theinjectedwaterbreakthroughinthiefzones,(B)injectionofnutrients
tostimulateindigenousbacteriaforproducingbioproducts.MEOR,microbialenhancedoilrecovery.(Credit:
fromSen,R.,2008.Biotechnologyinpetroleumrecovery:themicrobialEOR.ProgressinEnergyand
CombustionScience34(6),714e724.)
Theprimarychallengesassociatedwithtertiaryoilre- toenhancedoilrecoverycanbeclassifiedintosevenma-
covery are related to interrelationships between oil and jorgroupsasbiomass,biopolymers,biosurfactants,bio-
reservoircircumstances.Forexample,therelativelyhighly gases,bioacids,biosolvents,andemulsifiers(Pateletal.,
permeableregionscanmakethethiefzonesthatreduce 2015; Safdel et al., 2017). Biomass can significantly
thesweepefficiency.Theymakeitimpossibletorecover improveoilrecoverybybypassingtheinjectedwaterto
theoilthathasnotbeenincontactwiththeinjectedwater residualoilasaresultofselectivelypluggingtheporous
via traditional waterflooding (Sen, 2008; Ohms et al., media. Biopolymers can increase the oil recovery by
2010; Okeke and Lane, 2012). Water and oil have decreasing reservoir permeability and increasing water
different viscosities and also have surface tension due viscosity, which improve the mobility ratio. Bio-
to the immiscibility.The combination of them compli- surfactants have a significant effect on wettability alter-
catestheproductionmechanismofwaterflooding.Most ation by lowering surface and interfacial tensions.
oil reservoirs around the world have very complex bio- Biogasesare producedbycertainmicrobial speciesand
logicalsystems,makinglaboratoryexperimentsofmicro- contributetotherepressurizationofthereservoirtoin-
bial activity difficult. The microbes injected into the oil creaseoilrecovery.Bioacidsandsolventsdissolvesome
reservoirmustcompetewiththeindigenousmicroorgan- parts of the reservoir rock, increasing porosity and
isms(Sen,2008).Analyzingthedatacollectedfromthe permeability and consequently reducing entrapped oil.
322projects thatperformedthesameMEORprocesses, Oil emulsification can be achieved under conditions
Portwood(1995)providesusefulinformationtoanalyze where emulsifiers produced by a variety of microbes
thetechnicalandeconomiceffectivenessoftheprocesses form a stable emulsion with hydrocarbon (commonly
andtopredictthetreatmentresponsesinthegivenreser- oil-in-water)(Pateletal.,2015).Fig.1.2showsthestate
voirs.TheseMEORapplicationsresultedinasubstantial oftheoildropletsinaporousrockbeforeandafterthe
andsustainedincreaseinoilproductioncomparedwith emulsificationprocess(Sen,2008).Table1.1showsthe
otheroperatingresultsinthesamereservoir. listofmicrobialmetabolitesandmicroorganismsalong
In the MEOR processes, microorganisms produce a with the production problems, major effects, and best
varietyofmetabolitesthatcontributetoincreasingoilre- reservoircandidatesfortheMEORprocess.
covery(Sen,2008).Thesemetabolitesaffectnotonlythe
1.1.2 SelectivePlugging
petrophysical properties including porosity, perme-
ability, and wettability but also chemical properties Oneofthemajorfactorsinreducingoilrecoveryisthe
such as viscosity, interfacial tension (IFT), and so on high permeability zones of the reservoirs. These zones
(Guo et al., 2015). In general, the metabolites related makeitdifficulttoextracttheoilremaininginrelatively
