Waterflooding seminar (www.mpetro.ir)

Waterflooding Presentation – April 11, 2002Waterflooding Presentation – April 11, 2002
WATERFLOODINGWATERFLOODING
Hycal - WeatherfordHycal - Weatherford
April 2005April 2005

Presentation SummaryPresentation Summary
 Why does (and doesn’t) waterfloodingWhy does (and doesn’t) waterflooding
work in various reservoir situationswork in various reservoir situations
 What are the optimum conditions forWhat are the optimum conditions for
waterfloodingwaterflooding
 What are some common problemsWhat are some common problems
associated with waterfloodingassociated with waterflooding
 What are some novel applications forWhat are some novel applications for
waterflooding?waterflooding?
 Summary and conclusionsSummary and conclusions

Why Does the Basic TreatiseWhy Does the Basic Treatise
of Waterflooding ‘Work’ as aof Waterflooding ‘Work’ as a
Cost Effective RecoveryCost Effective Recovery
Method?Method?
 Compare to unsupported (non waterCompare to unsupported (non water
injection/influx supported) primary oilinjection/influx supported) primary oil
production to understand thisproduction to understand this

Primary Oil ProductionPrimary Oil Production
MethodsMethods
Oil Compression Drive (0.1-2%Oil Compression Drive (0.1-2%
OOIP)OOIP)
Compaction Drive (0.1 – 2%Compaction Drive (0.1 – 2%
OOIP)OOIP)
Solution gas drive (1-10% OOIP)Solution gas drive (1-10% OOIP)
Gascap drive (1-20% OOIP)Gascap drive (1-20% OOIP)

Solution Gas and GascapSolution Gas and Gascap
Drives Have Limited RecoveryDrives Have Limited Recovery
Generally Due to AdverseGenerally Due to Adverse
Viscosity and Mobility EffectsViscosity and Mobility Effects

Waterflooding is Often MuchWaterflooding is Often Much
More Effective ThanMore Effective Than
Gasflooding Due toGasflooding Due to
 Much better viscosity ratio results in betterMuch better viscosity ratio results in better
conformance and reduced coningconformance and reduced coning
 Lower density contrast minimizing gravityLower density contrast minimizing gravity
segregation in horizontal drive situationssegregation in horizontal drive situations
 Maintenance of driving pressure gradientMaintenance of driving pressure gradient
in reservoirin reservoir
 Prevention of formation of critical or freePrevention of formation of critical or free
gas saturations which reduce relativegas saturations which reduce relative
permeability to oilpermeability to oil

Waterflood RecoveryWaterflood Recovery
 Depends strongly on a number of factorsDepends strongly on a number of factors
to be discussedto be discussed
 Can be as high as 60% of the OOIP inCan be as high as 60% of the OOIP in
place in some favorable situationsplace in some favorable situations
 May be much lower in other casesMay be much lower in other cases
 There are generally optimum reservoirThere are generally optimum reservoir
types, conditions and implementationtypes, conditions and implementation
strategies for waterflooding to maximizestrategies for waterflooding to maximize
potential oil recoverypotential oil recovery

TYPES OFTYPES OF
WATERFLOODWATERFLOOD
OPERATIONSOPERATIONS

NaturalNatural
WaterfloodingWaterflooding

Infinite Aquifer TypeInfinite Aquifer Type
WaterfloodWaterflood
1 m31 m3
OutOut
1 m31 m3
InIn

Limited Aquifer TypeLimited Aquifer Type
1 m31 m3
OutOut
0.5 m30.5 m3
InIn

Passive Aquifer TypePassive Aquifer Type
1 m31 m3
OutOut
0 m30 m3
InIn

Modes of NaturalModes of Natural
WaterfloodsWaterfloods
Vertical drive (most effective)Vertical drive (most effective)
Edge or horizontal drive (lessEdge or horizontal drive (less
effective)effective)

Vertical Flood (Common in ReefVertical Flood (Common in Reef
Structures, thick vertical payStructures, thick vertical pay
sections)sections)

Edge Flood – Common in ThinEdge Flood – Common in Thin
Pay Zones with Little VerticalPay Zones with Little Vertical
ReliefRelief

‘‘Induced’Induced’

Induced WaterfloodsInduced Waterfloods
 In cases where good voidage replacementIn cases where good voidage replacement
by natural aquifer support is not presentby natural aquifer support is not present
waterflooding is often conducted bywaterflooding is often conducted by
injection of surface, produced or otherinjection of surface, produced or other
water into the formation of interest towater into the formation of interest to
simulate various types of natural watersimulate various types of natural water
drivedrive

Common Induced WaterfloodCommon Induced Waterflood
TypesTypes
 Edge drive (updip)Edge drive (updip)
 Bottom drive (gravity stabilized)Bottom drive (gravity stabilized)
 Line DriveLine Drive
 Advancing line driveAdvancing line drive
 Staggered line driveStaggered line drive
 PatternPattern
 Reservoir dictatedReservoir dictated

Updip Edge DriveUpdip Edge Drive

Vertically Stable BottomVertically Stable Bottom
DriveDrive

Advancing LineAdvancing Line
DriveDrive

Staggered LineStaggered Line
DriveDrive

Pattern Flooding – 5 SpotPattern Flooding – 5 Spot

Reservoir ControlledReservoir Controlled
OrientationOrientation
100 200 300 400 500 600 700 800
0
5
10
15
20

Factors ImpactingFactors Impacting
the Displacementthe Displacement
Effectiveness of aEffectiveness of a

MACROSCALE EFFECTSMACROSCALE EFFECTS
HeterogeneityHeterogeneity
Permeability contrastsPermeability contrasts
Reservoir continuityReservoir continuity
Faults and fracturesFaults and fractures
Directional permeability trendsDirectional permeability trends

MICROSCALE EFFECTSMICROSCALE EFFECTS
Pore size distribution and geometryPore size distribution and geometry
Capillary pressureCapillary pressure
WettabilityWettability
Relative permeability characterRelative permeability character
Advance rateAdvance rate
Injection fluid induced damageInjection fluid induced damage

MACROSCALEMACROSCALE
ISSUESISSUES

Reservoir HeterogeneityReservoir Heterogeneity

Permeability ContrastsPermeability Contrasts

ReservoirReservoir
ContinuityContinuity

Natural FracturesNatural Fractures

Natural Fractures Parallel toNatural Fractures Parallel to
the Line of Flowthe Line of Flow

Natural FracturesNatural Fractures
Perpendicular to the Line ofPerpendicular to the Line of
FlowFlow

Directional PermeabilityDirectional Permeability
Trends Can Give SimilarTrends Can Give Similar
PerformancePerformance

Presence of Sealing FaultsPresence of Sealing Faults

MicroscaleMicroscale
IssuesIssuesPrimarily Dominated by WettabilityPrimarily Dominated by Wettability
EffectsEffects

What is Wettability?What is Wettability?
 Preferential Attraction of a fluid to a solidPreferential Attraction of a fluid to a solid
surface in the presence of one or moresurface in the presence of one or more
other immiscible fluidsother immiscible fluids

Wettability TypesWettability Types
 Water WetWater Wet
 Oil WetOil Wet
 Neutral WetNeutral Wet
 Mixed WetMixed Wet
 Spotted WetSpotted Wet

Impact of Wettability onImpact of Wettability on
Relative Permeability toRelative Permeability to
Water and OilWater and Oil

Relative PermeabilityRelative Permeability
Water Saturation - Fraction
RelativePermeability-Fraction
Swi 10%
Crossover 22% Sw
Krw = 0.88
Swi approx 25%
Crossover approx 68%
Krw = 0.08

Typical RelativeTypical Relative
Permeability CurvePermeability Curve
Configurations forConfigurations for
Other WettabilityOther Wettability
TypesTypes

Neutral Wet FormationsNeutral Wet Formations
Swi 10-20%
Crossover around 50%
Krw = 0.45

Mixed WettabilityMixed Wettability
 A fairly common wettability type in whichA fairly common wettability type in which
tight microporosity is water saturated andtight microporosity is water saturated and
water wet, while oil saturated macroporeswater wet, while oil saturated macropores
are oil wetare oil wet

Typical Mixed WettabilityTypical Mixed Wettability
Relative Permeability CurvesRelative Permeability Curves
Swi = 40%
Crossover approx 55%
Krw = 0.70

Spotted/DalmatianSpotted/Dalmatian
WettabilityWettability
Swi = 22%
Crossover = 59%
Krw = 0.28

General Impact of WettabilityGeneral Impact of Wettability
on Rel Permon Rel Perm
FactorFactor WaterWater
WetWet
Oil WetOil Wet NeutralNeutral
WetWet
Mixed WetMixed Wet
SwiSwi >15%>15% <15%<15% 10-20%10-20% >15%>15%
CrossoverCrossover
PointPoint
> 50% Sw> 50% Sw < 50% Sw< 50% Sw ApproxApprox
50% Sw50% Sw
< 50% Sw< 50% Sw
Krw at SorKrw at Sor <0.2<0.2 >0.5>0.5 0.2-0.50.2-0.5 >0.5>0.5
Swi asSwi as
F(Perm)F(Perm)
StrongStrong NoneNone WeakWeak StrongStrong
SorwSorw >20%>20% >20%>20% <25%<25% <25%<25%

Specific Impact ofSpecific Impact of
Wettability onWettability on
PerformancePerformance

Concept of ‘Mobility Ratio’Concept of ‘Mobility Ratio’
M = µο x Krw
µ w x K r o
Mobility Ratio
Viscosity of
Displaced Phase
Rel Perm of
Displacing
Phase
Viscosity of
Displacing Phase
Rel Perm of
Displaced
Phase

Favorable vs. UnfavorableFavorable vs. Unfavorable
Mobility RatioMobility Ratio

Factors Improving MobilityFactors Improving Mobility
M = µο x Krw
µ w x K r o
Low Oil Visc Low Krw / Krg
High Displacing
Phase Visc
High Kro

Example – Waterflood in aExample – Waterflood in a
Favorable Mobility SystemFavorable Mobility System
(M=0.5)(M=0.5)

Example – Waterflood in aExample – Waterflood in a
Unfavorable Mobility SystemUnfavorable Mobility System
(M=20)(M=20)

Wettability and MobilityWettability and Mobility
EffectsEffects
 Since relative permeability endpointSince relative permeability endpoint
values are strongly impacted byvalues are strongly impacted by
Wettability, oil vs. water wet systems mayWettability, oil vs. water wet systems may
have order of magnitude difference inhave order of magnitude difference in
water-oil mobility ratiowater-oil mobility ratio
 Can substantially impact the economics ofCan substantially impact the economics of
a natural or induced water drive processa natural or induced water drive process

Residual Oil Saturations inResidual Oil Saturations in
 BREAKTHROUGHBREAKTHROUGH SorSor
 ECONOMICECONOMIC SorSor
 ULTIMATEULTIMATE SorSor

Breakthrough SorBreakthrough Sor
 Refers to residual oil saturation in theRefers to residual oil saturation in the
swept pattern at the time ofswept pattern at the time of firstfirst waterwater
productionproduction
INJ PROD

Economic SorEconomic Sor
swept pattern at the time ofswept pattern at the time of MaximumMaximum
EconomicEconomic water cutwater cut
INJ PROD

Ultimate (True) SorUltimate (True) Sor
swept pattern if a nearswept pattern if a near InfiniteInfinite volume ofvolume of
water were displaced to near zero oil cutwater were displaced to near zero oil cut
INJ PROD

Lab Measurements of SorLab Measurements of Sor
 Lab measurements of Sor generally give aLab measurements of Sor generally give a
reasonable approximation of thereasonable approximation of the
ULTIMATE Sor since usually a very largeULTIMATE Sor since usually a very large
number of pore volumes of displacementnumber of pore volumes of displacement
are conducted (10-100 typical)are conducted (10-100 typical)

Waterflooding in DifferingWaterflooding in Differing
Wettability ReservoirsWettability Reservoirs
Cumulative Pore Volumes of Injection
PercentRecoveryOOIP
Breakthrough Sor
Economic Sor
Ultimate Sor

Waterflooding in DifferingWaterflooding in Differing
Wettability ReservoirsWettability Reservoirs
Cumulative Pore Volumes of Injection
PercentRecoveryOOIP

Given this – What are theGiven this – What are the
Optimum Reservoir WettingOptimum Reservoir Wetting
Conditions for aConditions for a
Waterflood?Waterflood?

This Depends Strongly onThis Depends Strongly on
Which Criteria Dominate theWhich Criteria Dominate the
EvaluationEvaluation
Ultimate oil recovery?Ultimate oil recovery?
Speed of oil recovery?Speed of oil recovery?
Ease of injection?Ease of injection?
Minimum water cycling andMinimum water cycling and
disposal costs?disposal costs?

Residual Oil Saturation atResidual Oil Saturation at
Infinite PV of OilInfinite PV of Oil
Displacement vs. WettabilityDisplacement vs. Wettability
USBM Wettability Index
-1.5 +1.50
Oil Wet Water WetNeutral

For Maximum Ease of WaterFor Maximum Ease of Water
InjectionInjection
Oil
Wet!

For Maximum Oil RecoveryFor Maximum Oil Recovery
and Lowest Residual Oiland Lowest Residual Oil
SaturationSaturation
Neutral/Mixed
Wet

For Most Rapid Oil RecoveryFor Most Rapid Oil Recovery
and Minimum Waterand Minimum Water
ProductionProduction
Water
Wet!

OptimumOptimum
Conditions?Conditions? In most cases, optimum economicIn most cases, optimum economic
recovery efficiency is achieved when therecovery efficiency is achieved when the
wetting condition is a strongly water wetwetting condition is a strongly water wet
as possibleas possible

Does This Mean if myDoes This Mean if my
Reservoir isReservoir is NOTNOT Water WetWater Wet
Waterflooding WillWaterflooding Will NOTNOT bebe
Economic?Economic?
To Flood?
To Not to Flood?
???

Many Successful WaterfloodsMany Successful Waterfloods
have been Conducted in Oilhave been Conducted in Oil
Wet and Mixed WetWet and Mixed Wet
ReservoirsReservoirs
 Overall economic benefit may be less thanOverall economic benefit may be less than
if the reservoir had been strongly waterif the reservoir had been strongly water
wet, but may still represent substantialwet, but may still represent substantial
improvement over straight primaryimprovement over straight primary
depletiondepletion

InterfacialInterfacial
Tension ForcesTension Forces

Interaction of Wettability,Interaction of Wettability,
Interfacial Tension andInterfacial Tension and
Pore Size DistributionPore Size Distribution
Pc=2σ(Cosφ)
r

Interfacial TensionInterfacial Tension
 Water - Oil (0.2-40 dyne/cm)Water - Oil (0.2-40 dyne/cm)
 Gas-Water (2-70 dyne/cm)Gas-Water (2-70 dyne/cm)
 Gas-Oil (0-60 dyne/cm)Gas-Oil (0-60 dyne/cm)
 F(composition (H2S, CO2), temperatureF(composition (H2S, CO2), temperature
and pressure)and pressure)

Global Effect of IFT on Water-OilGlobal Effect of IFT on Water-Oil
Relative Permeability/Sor – IFTRelative Permeability/Sor – IFT
Dominated SystemDominated System
Water Saturation - FractionWater Saturation - Fraction
RelativePermeabilityRelativePermeability
K
ro
K
ro
Krw
Krw

Global Effect of IFT on Water-OilGlobal Effect of IFT on Water-Oil
Relative Permeability/Sor – IFTRelative Permeability/Sor – IFT
Dominated SystemDominated System
Water Saturation - FractionWater Saturation - Fraction
RelativePermeabilityRelativePermeability
Kro
Kro Krw
Krw

Why do some low IFTWhy do some low IFT
injections not result ininjections not result in
large incremental oillarge incremental oil
recovery?recovery?

Sor – IFT Effects in WaterSor – IFT Effects in Water
Wet RockWet Rock
Pore Throat Diameter Profile - Microns
FrequencyCount
Microporosity is Water
Saturated in WW Rock

Wet RockWet Rock
FrequencyCount
A Given IFT Level Allows
Access to Pore Throats Larger
Than a Certain Size
AccessibleInaccessible

Wet RockWet Rock
FrequencyCount

Sor – IFT Effects in Oil WetSor – IFT Effects in Oil Wet
RockRock
FrequencyCount
Microporosity is Oil
Saturated in OW Rock
Small Sw Generally is
In Center of Macropores
in OW Rock

Sor – IFT Effects in Oil WetSor – IFT Effects in Oil Wet
RockRock
FrequencyCount

Non Uniform Pore System –Non Uniform Pore System –
Macropore DominatedMacropore Dominated
FrequencyCount
AcceInaccessible

Non Uniform Pore System –Non Uniform Pore System –
Micropore DominatedMicropore Dominated
FrequencyCount

The dominance of Wettability,The dominance of Wettability,
IFT or Mobility controlsIFT or Mobility controls
recovery and injectivityrecovery and injectivity

Results of a Constant IFTResults of a Constant IFT
Flood in the ReservoirFlood in the Reservoir
Dominated by IFT EffectsDominated by IFT Effects
RelativePermeability

Results of a Constant IFTResults of a Constant IFT
Flood in the ReservoirFlood in the Reservoir
Dominated by Mobility EffectsDominated by Mobility Effects

Waterflood RequirementsWaterflood Requirements
#1 Suitable Reservoir
#2 Water!!!

Typical Water SourcesTypical Water Sources
 Produced water(s) (Native and non nativeProduced water(s) (Native and non native
to formation)to formation)
 Surface water (Rivers, lakes, etc)Surface water (Rivers, lakes, etc)
 Shallow ground waterShallow ground water
 Waste water streamsWaste water streams
 Often a mixture of some of the aboveOften a mixture of some of the above

Surface Water
Shallow Aquifer
Producing
Formation
Deep Aquifer
Surface Water - Direct Intake

Surface Water
Shallow Aquifer
Producing
Formation
Deep Aquifer
Surface Water - Infiltration Gallery

Surface Water
Shallow Aquifer
Producing
Formation
Deep Aquifer
Shallow Aquifer

Surface Water
Shallow Aquifer
Producing
Formation
Deep Aquifer
Formation Water

Surface Water
Shallow Aquifer
Producing
Formation
Deep Aquifer
Deep Aquifer

Injection Water QualityInjection Water Quality
IssuesIssues
 Sufficient volume for future requirements?Sufficient volume for future requirements?
 Reliable year round source?Reliable year round source?
 Total suspended solids content (TSS)Total suspended solids content (TSS)
 Oil and Grease Content (OGC)Oil and Grease Content (OGC)
 Total dissolved solids content (TDS)Total dissolved solids content (TDS)
 Scaling indexesScaling indexes
 Specific ionic compositionSpecific ionic composition

Screening andScreening and
ProcessProcess

General ProcessGeneral Process
MacroscaleMacroscale
ScreeningScreening
MicroscaleMicroscale
ScreeningScreening
WaterWater SourceSource
AndAnd QualityQuality
Simulation,Simulation,
ImplementationImplementation

Typical Screening Studies ConductedTypical Screening Studies Conducted
on a Lab Basis (Microscale andon a Lab Basis (Microscale and
Water Quality Sections)Water Quality Sections)
 Pore size distributionPore size distribution
 WettabilityWettability
 Capillary pressureCapillary pressure
 Relative PermeabilityRelative Permeability
 Interfacial TensionInterfacial Tension
 Water qualityWater quality
 Injectivity studiesInjectivity studies
 Stimulation StudiesStimulation Studies
 Conformance controlConformance control

Pore Size DistributionPore Size Distribution
 Mercury injection studiesMercury injection studies
 Thin section studiesThin section studies
 Image analysis studiesImage analysis studies

WettabilityWettability
 Contact AngleContact Angle
 Amott/Combined Amott-USBM methodAmott/Combined Amott-USBM method
-200
-150
-100
-50
0
50
100
150
200
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Water Saturation, fraction of PV
CapillaryPressure,kPa

Capillary PressureCapillary Pressure
 Porous PlatePorous Plate
 Centrifuge methodsCentrifuge methods
 Air-Mercury conversionAir-Mercury conversion
0
100
200
300
400
500
600
700
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Oil Saturation, fraction of PV
CapillaryPressure,kPa

Relative PermeabilityRelative Permeability
 Steady StateSteady State
 Unsteady StateUnsteady State
 Reservoir/Ambient conditionReservoir/Ambient condition
Gas/Oil Relative Permeability Profile
0.001
0.01
0.1
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Gas Saturation (fraction)
Krg
Kro

Interfacial TensionInterfacial Tension
 Dunoue RingDunoue Ring
 Spinning DropSpinning Drop
 Drop PendantDrop Pendant

Water QualityWater Quality
 CompositionComposition
 Suspended solidsSuspended solids
 Oil and grease contentOil and grease content
 Bacterial content/typingBacterial content/typing
 pHpH

Injectivity StudiesInjectivity Studies
Water sensitivityWater sensitivity
Critical salinityCritical salinity
Critical FiltrationCritical Filtration
Phase trappingPhase trapping
Bacterial growthBacterial growth

StimulationStimulation
 Acidization for scale removalAcidization for scale removal
 Solvent treatments (paraffin's,Solvent treatments (paraffin's,
asphaltenes, oil blocks, etc)asphaltenes, oil blocks, etc)
 Fracture optimizationFracture optimization
 Near wellbore wettability alterationNear wellbore wettability alteration
evaluationsevaluations

Conformance ControlConformance Control
 Water diversion and shutoff treatmentsWater diversion and shutoff treatments
GelsGels
PolymersPolymers
Relative permeability modifiersRelative permeability modifiers

ConclusionsConclusions
 Waterflooding can result in significant additionalWaterflooding can result in significant additional
incremental oil recovery in many reservoirincremental oil recovery in many reservoir
situationssituations
 Not all reservoirs are prime waterfloodNot all reservoirs are prime waterflood
candidatescandidates
 Macroscale features may control theMacroscale features may control the
effectiveness of a waterfloodeffectiveness of a waterflood
 Mobility dominates microscale sweep efficiencyMobility dominates microscale sweep efficiency
 A detailed protocol for evaluation has beenA detailed protocol for evaluation has been
presentedpresented

Thanks for YourThanks for Your
Attention!Attention!
Is it Over
Yet???

Waterflooding seminar (www.mpetro.ir)

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