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8/3/2019 EOR Details

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ENHANCED OIL RECOVERYENHANCED OIL RECOVERY

METHODS TO MAXIMIZE RECOVERY FROMMETHODS TO MAXIMIZE RECOVERY FROM

MATURE FIELDSMATURE FIELDS


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Enhanced Oil RecoveryEnhanced Oil Recovery

EOR normally known as tertiary recovery process

Applied to mobilize trapped oil in pores held up by

viscous and capillary forces

Thermal, chemical, solvent/gases are the most common

forms of various EOR processes

EOR is normally applied after primary and secondary

recovery. However these can be applied at any stage of

a producing field depending upon the performancehistory


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Volumetric sweepXDisplacement efficiency

Areal sweepXVertical sweepXDisplacement efficiency

Areal sweep depends onthe fluid mobility ,pattern type, aeal hetegeneity & total

volume of fluid injected

Vertical sweep is governed byvertical heterogeneity, gravity segregation, fluid mobilities

& total fluid injected

Displacement efficiency is a function of

injection rate, viscosity, density and IFT of displacing fluid

Defined as

Basic purpose of EOR processes is to improvesweep and displacement efficiency

Recovery FactorRecovery Factor


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Role of Mobility ratio and Capillary number on recoveryRole of Mobility ratio and Capillary number on recovery

To control the mobility ratio, increase the viscosityof water or reduce the viscosity of oil

This can be achieved by thickening water by polymer

or heat application

M =M = w//o = Krw/ KroXo/w

e.g. 100 / 0.5 = 200, water is 200 times moremobile compared to oil

Mobility ratioMobility ratio


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If can be reduced by the order of 1000 ROS can bereduced to 10-15 %

Capillary numberCapillary number

Capillary number =Capillary number = v /

= viscosity in cp

v = darcy velocity of displacing fluid

= IFT interfaced between displaced fluid and brine


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Need for EORNeed for EOR

To maximize recovery after primary andsecondary recovery from mature fields whichis currently 30-50 %

Risk of applying EOR is considered reduced

in view of better understanding, advances inR & D studies and successful pilot tests andfield tests

Declining production trends and lesser largesized discoveries are important for EOR totap additional oil


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Part IPart I

Chemical EOR


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Chemical EOR processesChemical EOR processes These are applied in tertiary mode to mobilize the oil in

pores held by capillary forces and adhesive forces and thus

to reduce the ROS

This can be applied in secondary mode in combination with

other displacement processed such as water or gas

Basic mechanism involved are

Reduction in interfacial tension between oil and brine

Solubilization of released oil

Change in the wettability towards more water wet

reducing mobility contrast between crude oil and

displacing fluid


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In surfactant assisted chemical EOR it is mainly

IFT reduction, wettability change and solubilization

In polymer assisted chemical EOR it is

mobility control and improving sweep efficiency

Contd


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Various chemical EOR processesVarious chemical EOR processes

Micellar/surfactant polymer flooding

Alkaline flooding Alkali-surfactant flooding

Alkali-surfactant-polymer flooding Polymer flooding


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Selection of chemical EOR processesSelection of chemical EOR processes

Type of reservoir

Rock mineralogy, clay, heterogeneity Reservoir pay thickness, K,

Reservoir temperature

Reservoir oil properties

ROS

Salinity of formation water and presence ofbivalent cations


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Technical screening criteria for chemicalTechnical screening criteria for chemical

processesprocessesASP/Micellar Polymer

Crude Oil

Gravity,0API > 20 >15

Viscosity, cp < 35 35 >50

Formation water salinity Chloride < 20000 ppm, Ca + Mg < 500 ppm

Type of Formation Sandstone preferred

Average permeability, >50 md

Depth and Temperature < 9000 ft, Temperature < 2000F


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Application of various chemical EOR processesApplication of various chemical EOR processes

Micellar polymer flooding/surfactant polymer flooding

Classic micellar polymer flooding consists of injecting a slug

that contains surfactants, polymers, electrolyte, co-solvents

and oil The size of slug may vary from 5-15 % PV (for high surfactant

concentration system) 15-50% PV (low surfactant concentration

system) Micellar process is highly effective, but it is costly

Low adsorption surfactant developed can replace the micellar

solution and can be directly used in combination with thepolymer as a surfactant polymer flooding

Recovery of the surfactant in SP flooding is comparable or

even higher than ASP or micellar flooding


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Polymer processPolymer process

The process improve recovery by reducing the mobility contrast between

oil and water and improving the overall sweep efficiency

The polymer process can be applied in secondary mode to improve the

efficiency of water flood

It can also be applied in combination with other chemical EOR such as

alkali, surfactant and ASP processes to improve the mobility of the

respective processes

This process does not reduce ROS

AlkalineAlkaline--SurfactantSurfactant--Polymer FloodingPolymer Flooding

The process is normally applied in tertiary mode to reduce ROS Addition of alkali and low slug volume make the process cost

effective

Recovery in range of 15-25 % is observed


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AlkalineAlkaline--Surfactant FloodingSurfactant Flooding

This process is applied in light oil reservoirs wherepolymer is not required

This can be applied in both carbonate as well assandstone formations

However in the absence of mobility control displacementefficiency are low

Large slug volume is required

It can be combined with other EOR processes like gasinjection to improve performance

Addition of alkali

Advantages of adding alkali with surfactants improves the wetting characteristics of the rock

reduces the adsorption of surfactants

produces natural surfactant if crude is acidic


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Alkaline / Alkaline Polymer FloodingAlkaline / Alkaline Polymer Flooding

Applied in viscous crude with high acid number

Formation of tough emulsions observed in many

cases

Reaction of alkali with clays and zeolites makes theprocess less effective

Corrosion is also a problem associated with the

alkali process


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Selection of surfactant and alkaliSelection of surfactant and alkali Surfactants and alkali are integral part of

chemical flooding Selection of surfactant is based on

Ability to reduce IFT between crude and brine

Thermal stability

Tolerance to salinity and hardness of brine

Solubility in brine

Phase behaviour parameters

Adsorption test under static and dynamic conditions Displacement studies under reservoir conditions

Selection of alkali is guided by

Type of formation, clay type & bivalent cations

In carbonate reservoirs Na metaborate is used inplace of other alkali

If reservoir contains clays NaHCO3 is preferred

Na2CO3 is the most commonly used alkali. It ischeap and transports better in porous media


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Advances in the area of surfactants and polymers

High performance surfactants have been developed which

tolerates salinity up to 100000 ppm and 2500 ppm bivalent cation

SS surfactants show very low adsorption compared to

conventional. Can be used alone or as SP flooding without alkali.

Blends of surfactants mixtures improves WF efficiency

significantly.

Surfactants are available which are thermally stable up to 2600C

Recent R & D studies indicate that sulphonated acrylamide

copolymers can tolerate high bivalent cations and temperature

up to 1200C


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Types of surfactants used in EORTypes of surfactants used in EOR

Normally anionic surfactants are used for EORapplications. Some blends of different surfactants arealso used to get low IFT conditions and favourablewettability changes

Surfactants used in EOR are the following types;

Petroleum sulphonate (PS), for reservoirs with temperature,low salinity and bivalent cations

-olefin sulphonate Internal olefin sulphonate

Alkyl-Aryl sulphonate, for high temperature applications

Ethoxylated alcoholThermal stability of the surfactants are in the following orderThermal stability of the surfactants are in the following order

Better tolerance to salinity

and hardness,high temperature stability

AAS > IOS > AOS > PS >AAS > IOS > AOS > PS > EthoxylatedEthoxylatedalcoholalcohol


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Advantages of chemical EOR processesAdvantages of chemical EOR processes

Right blend of chemical system can increaserecovery factor by 15-20 %

Chemical processes can be combined with otherEOR processes to derive advantage of each other

Processes can be tailor made to suit specific crudeand reservoir conditions

Can be applied in both sandstone and carbonateformations

Can improve recovery of polymer flooding after it

reaches its limit Low tension flooding improves the efficiency of

water flooding/injectivity


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Limitations of chemical EOR processesLimitations of chemical EOR processes Adsorption of chemicals on rock surfaces, particularly in

carbonate formations and sandstone formations

containing zeolites/clays Chromatographic separation of chemical where thickness

vary

Dilution of chemical in active water reservoir Incompatibility with formation fluids in which high

bivalent-cations are present

High temperature and high salinity limits application ofchemical processes. Reaction of alkali with clays andswelling causes permeability reduction


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Case history of chemical EOR (Indian scenario)Case history of chemical EOR (Indian scenario)

SanandSanand Polymer FloodPolymer Flood

Because of mobility contrast and low primary recovery, it was decided to

go for polymer flooding



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Polymer pilot, 1985

Expanded pilot, 1993

Commercial scheme

Scheme, 1999

Polymer Injectors

Chase WaterInjectors

New polymer injectors


Performance of polymer floodPerformance of polymer flood


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Performance of polymer floodPerformance of polymer flood

Production increased from 100 M3/day to 400 M3/day Water cut reduced from 88% to 68%

WC remains constant since last 6 years (63-68%) Current recovery 25 % Expected recovery 36 % by 2030

Performance Plot of KS-III sand of Sanand Field

0

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May-71

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OilRate

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Qo m3/d

w/c % PilotExtended

Pilot

Commerc

ialisation


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VirajViraj ASP PilotASP Pilot

Based on the low primary recovery and mobilityBased on the low primary recovery and mobility

contrast and high acid number of the crude, ASP pilotcontrast and high acid number of the crude, ASP pilot

was decided in the Fieldwas decided in the Field

P f l t f Vi j ASP Pil t


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Performance plot of Viraj ASP Pilot

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/C,%

Base oilrate Oil rate W/C

PB-2PB-1 PB-3 C/W C/W

stop

ASP

ObservationsObservations


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ObservationsObservations Pilot was successful with increase in production

Preferential movement of chemical Water cut increase at start of buffer and chase water

injection

Simulation studies indicate slug size and polymerconcentration on low side

Lesson learned from this pilot are being taken care

in other upcoming pilots

Other envisaged pilotsOther envisaged pilots ASP Jhalora

ASP Kalol

ASP Mangala


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Number of active chemical projectsCountry

Polymer Micellar/Polymer

ASP

USA 4 - -

China 18 - -

France 1 - -

India 1 1

Indonesia - 1 -

Venezuela - - 2

Total 24 1 3

Chemical EOR - World Scenario (Active projects)


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Part IIPart II

GAS Flooding


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Gas FloodingGas Flooding

This process is mostly applied in light and tight

reservoir because of its high microscopic

displacement efficiency

This process can be combined with other recovery

processes such as water or surfactant system.

It can be applied in both miscible and immiscibleways

The efficiency of miscible process is high compared

to immiscible process


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Various types of gas floodingVarious types of gas flooding

Hydrocarbon flooding (LPG, Enrichedand Lean gas)

CO2 flooding N2 and Flue gas injection


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COCO2 flooding (Miscible/Immiscible)flooding (Miscible/Immiscible)

The process is the most widely used and involves the injectionof CO2 (15-30 % of HCPV) into reservoir

CO2 recovers oil by

Swelling the crude oil (CO2 is highly soluble in low gravityoil)

Lowering the viscosity of oil (much more than nitrogen andmethane)

Lowering the IFT between oil and CO2/oil phase in nearmiscible region

Generation of miscibility

The CO2 flooding is similar to vapourizing gas drive but only

difference in CO2 process is that wider range of C2-C30 areextracted

CO2 flood process is applicable to wider range of reservoirs

because of its lower miscibility pressure than that forvapourizing gas drive

Screening criteria of CO2 Flood


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g 2

Recommended Range of current projects

Crude Oil

Gravity,0API > 22 27 to 44

Viscosity, cp < 10 0.3 to 6

Composition High percentage Of Intermediate Hydrocarbons (Especially C5

to C12

)

Reservoir

Oil saturation, %PV > 20 15 to 70

Type of Formation Sandstone or carbonate and relatively thin unless dipping

Average permeability, md Not critical if sufficient injection rates can be maintained.

Depth should be enough to allow injection pressures greater than the MMP,which increases with temperatures and for heavier oils. Recommended depths

for CO2 floods are as follows:Depth and Temperature

Oil Gravity, oAPI Depth must be greater than,(ft)

> 40 2500

32 to 39.9 2800

28 to 31.9 3300

22 to 27.9 4000

< 22 Fails for miscible

13 to 21.9 1800


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Hydrocarbon flooding processHydrocarbon flooding process

(miscible/immiscible)(miscible/immiscible)

Generating miscibility (in the condensing and

vapourizing gas drive)

Increasing oil volume by swelling Decreasing the oil viscosity

Immiscible gas displacement, especially enhanced

gravity drainage with reservoir conditions

Hydrocarbon miscible flooding recovers crude oil byHydrocarbon miscible flooding recovers crude oil by


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LPG Process

Consists LPG (5% of HCPV) followed by natural gasand water

Enriched gas process

Process consists of injecting natural gas (10-20%

HCPV) enriched by C2-C6 followed by lean gas andwater

High pressure lean gas injection (vapourizing gas

drive) Injection of lean gas at high pressure help to

vapourize C2-C6 component of crude oil being

displaced

Different HC Flooding Process are

Screening criteria for Hydrocarbon Miscible process


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Crude OilGravity,0API > 23 24 to 54 (miscible)

Viscosity, cp < 3 0.04 to 2.3

Composition High percentage of light hydrocarbons

Reservoir


Type of Formation Sandstone or Carbonates with minimum of fracturesand high permeability streaks

Net thickness, ft Relatively thin unless formation is dipping

Average permeability, md Not critical if uniform

Depth, ft > 4000 4040 to 15900

Temperature,0F Temperatures can have significant effect on theminimum miscibility pressure (MMP); it normally raisesthe pressure required. However, this is accounted for in

the deeper reservoirs that are needed to contain thehigh pressures for the lean gas drives.

NN /Flue gas flooding/Flue gas flooding


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This process recovers oil byvapourizing the lighter component in the crude

generating miscibility if the pressure is high

enough providing a gas drive where significantportion of the reservoir is filled with low cost gases

Enhancing gravity drainage in the dipping

reservoir

It can be applied in both miscible as well as

immiscible way depending on the temperature,pressure and oil composition

Because of low cost large volumes can be injected

N2/Flue gas can also be used as chase gas for HC andCO2 flood

NN22/Flue gas flooding/Flue gas flooding

Screening of N2 & Flue Gas Flood


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Crude Oil

Gravity,0API > 35 38 o 54 (miscible)

Viscosity, cp < 0.4 0.07 to 0.3

Composition High percentage of light hydrocarbonsReservoir


Type of Formation Sandstone or carbonates with few fractures andhigh permeability streaks

Net thickness, ft Relatively thin unless formation is dipping

Average permeability, md Not critical

Depth, ft > 6000 10000 to 18500

Temperature,0F Not critical for screening purposes, even though thedeep reservoirs required to accommodate the highpressure will have high temperatures.

g 2

Advantages of different gas flooding processesAdvantages of different gas flooding processes


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g g g pg g g p

CO2 flood process can be applied to wider range of reservoirbecause of its lower miscibility than that for vapourizing gasdrive

Oil recovery are high in miscible displacement, less in

immiscible displacement It swells the oil and reduces its viscosity even before miscibilityis achieved

CO2flooding

HC flooding

Recovery factor in miscible HC flooding (LPG & Enriched) isquite high

Suitable for tight as well as light oil reservoirs

Can be applied both in carbonate and sandstone formations

Can be applied in reservoir depths ranging from 1000-5000meters

It is a cheaper process and large volume can be applied Can be applied in deep, tight and light reservoirs

N2flooding

Limitations of Gas flooding processesLimitations of Gas flooding processes


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NN2/Flue gas Flooding/Flue gas Flooding

Can be applied only in high gravity and deep reservoirs Miscibility pressure is quite high, can not be applied in depleted

reservoirs with high temperature

Separation from non hydrocarbon gases from hydrocarbon

gases at the surface Recovery efficiency is low (


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Sources of CO2 act as limitations for process to be applied CO2 gets dissolved into formation water making it acidic,

causing corrosion of tubulars

COCO2 FloodingFlooding

Common limitations in gas flooding processesCommon limitations in gas flooding processes Mobility control is an area of concern

Viscous fingering may result in poor vertical/horizontal sweep

Steeply dipping formation is desired for gravity stabilization ofthe displacement front, both for miscible and immiscibledisplacement

Early breakthrough of gas is another issue, particularly if the

reservoir contains natural and induced fractures Large volume of gas requirement makes the process expensive

Attaining miscibility in depleted reservoirs with hightemperature is an area of concern

Immiscible displacement yields lesser recovery compared tomiscible displacement

Oth fl diOth fl di


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Other gas flooding processesOther gas flooding processes

To derive the benefit of microscopic displacementefficiency of gases and megascopic displacement

efficiency of water different combined EORprocesses have been developed such as

Water Alternate Gas

Simultaneous Water and Gas Injection

Surfactant alternate Gas Flooding

Foam flooding

Case historyCase history


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Reservoir parameters

Depth 2900m Temperature 1260C Thickness 4 m API Gravity 45 Initial saturation 52.5% MMP 270 kg/cm2

Details of Pilot

Started in 1999

Initial gas injection 200000 m3/day through 4 injectors

Current gas injection 700000 m3/day

y

Miscible HC Gas Injection: Gandhar GS-12

ContdContd


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Waterflood Recovery : 36 %

HC Miscible Gas Inj. Recovery : 58 %

Gas Injectors : 14 (700,000 m3/d)

Avg Res Pressure : 270 ksc

Oil rate / water cut : 800 m3/d / 1%

1991 92 93 94 95 96 97 98 99 2000 01 02 03 04 05 06 070

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OilRate

(m3/d)

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re(kg/cm2)

Gas Inj

Gas Flooding World Scenario


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Number of active Gas Injection ProjectsCountry

Carbon Dioxide HC Others

USA 71 8 4

Canada 2 29 1

Libya - 1 -

China - - -

Colombia - - -

India - 1 -

Mexico - - 1

UAE - 1 -

Indonesia - - -Trinidad 5 - -

Venezuela - 8 1

Turkey 1 - -

Total 79 48 7

Gas Flooding - World Scenario


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Part IIIPart IIIThermal EOR

Thermal EORThermal EOR


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Thermal methods normally are used:Thermal methods normally are used:

To recover viscous and thick oilTo recover viscous and thick oil41% EOR oil of all EOR process produced by thermal41% EOR oil of all EOR process produced by thermal

process.process.

Physical and chemical changes occur because heatPhysical and chemical changes occur because heatsupplied.supplied.

Changes occur in form of reduction in:Changes occur in form of reduction in:

ViscosityViscositySpecific gravitySpecific gravity

IFTIFT

The principle of all the thermal processes are same i.e.The principle of all the thermal processes are same i.e.reduction of viscosity. Only pathways are different.reduction of viscosity. Only pathways are different.

Chemical changes involve different reaction such asChemical changes involve different reaction such as

cracking and dehydrogenation to produce low molecular wtcracking and dehydrogenation to produce low molecular wtcompoundcompound

Contd..Contd..


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The products of oxidation and combustion such asflue gases, hot water steam or vapourised lighter

fraction in different thermal processes, also help inreducing the viscosity and act as artificial drivingforces to mobilize oil towards producers

Only in low temperature oxidation (HPAI) in light oilreservoir, viscosity reduction is less dominantcompared to role of intermediate products which

acts as artificial driving force increasingmicroscopic displacement efficiency


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Thermal EOR ProcessesThermal EOR Processes

Mainly there are two types thermal EOR processes

Steam Flood

In-situ combustion process (HTO & LTO)

Steam Flood ProcessSteam Flood Process


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Steam Flood ProcessStea ood ocess

Steam flooding, CSS and SAGD are various form ofsteam injection process

Functions:- Steam recovers the crude oil by heating the crude and

reducing its viscosity

Supplying pressure to drive oil to the producing wells

Heat also distills lighter components which condenses inoil bank ahead of steam further reducing oil viscosity

The hot water that condenses from steam acts as artificial

drive to sweep oil toward producers Steam also lowers IFT also which detach paraffin and

asphaltene from the rock surface

Criteria for Selection of Steam FloodCriteria for Selection of Steam Flood


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Crude Oil

Gravity,0API 8-25 8-27

Viscosity, cp < 100000 10-137000

Composition Light ends for steam distillation will help

Reservoir

Oil saturation, %PV > 40 35-90

Type of Formation Sandstone with high porosity and permeability

Net thickness, ft >10 ft

Average permeability, md > 200 md 63-10000 md

Depth, ft 300-500 150-4500

Temperature,0F Not critical 60-2800C

Limitation of Steam Flood ProcessLimitation of Steam Flood Process


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Process is applicable:

In shallow and thick, high permeability sand stone andunconsolidated sand to avoid heat loss in well andadjacent formation

Steam flooding is not normally used in carbonateformation and also where water sensitive clays arepresent

Also high mobility and challenging of steam may makethe process unattractive

In high depth reservoir maintaining steam quality is notpossible

Because of very high temperature special metallurgytubing required in producers and injectors

Cost per incremental bbls is high

Normally 1/3 of incremental oil is used in generation ofsteam

InIn situ Combustion Processsitu Combustion Process


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InIn--situ Combustion Processsitu Combustion Process

There are two type of in-situ combustion processes,

High temperature oxidation (HTO) and low

temperature oxidation (LTO)

High temperature oxidation (500 600C) is forheavy oil

Low temperature oxidation (150 - 300C) is used

for light oil

High Temperature InHigh Temperature In--situ Combustion Processsitu Combustion Process


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High Temperature InHigh Temperature In-situ Combustion Processsitu Combustion Process

Functions:

In situ combustion recovers crude oil by application of heatwhich is transferred downstream by conduction and

convection process thus lowering the viscosity of crude

As fire moves produced mixture of hot gases, steam and hotwater which reduces viscosity of oil and displaces toward

producers Light oil and steam move ahead of burning front and condense

in liquid add the advantage of miscible displacement and hotwater flooding

Criteria for Selection of InCriteria for Selection of In--situ Processessitu Processes


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Crude Oil

Gravity,0API 10-27 10-40

Viscosity, cp < 5000 6-5000

Composition Some asphaltic component to aid coke formation

Reservoir

Oil saturation, %PV > 50 60-94

Type of Formation Sand or sandstone with high porosity

Net thickness, ft >10 ft

Average permeability, md > 50 md 85-4000 md

Depth, ft 1000C 100-2200C

LimitationsLimitations


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Process will not sustain if sufficient coke is not formed.Hence not suitable for paraffinic crude

Excessive deposition of coke also leads to slow advance

of combustion front Oil saturation and porosity should be high to minimise

the heat loss

The process trends to sweep upper part of reservoir,therefore sweep efficiency in thick reservoir is less

Problem associated with ISC processProblem associated with ISC process


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Problem associated with ISC processp

Complex process which is capital intensive anddifficult to control

Unfavourable mobility ratio and early break throughof combustion front

Produced flue gases pose environmental problem

Operational problem such as Severe corrosion bylow pH, hot water, tough emulsion, increase sandproduction, deposition of carbon and pipe failure in

producing wells because of high temperature

High Pressure Air Injection (HPAI)High Pressure Air Injection (HPAI) The process can be applied in tight and light oil reservoirs


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The process can be applied in tight and light oil reservoirs The oil recovery mechanism by this process is flue gas

sweeping and thermal effect generated by oxidation andcombustion

The process is similar to ISC, but oxidation reaction pathwaysare different for light and heavy oil

In case of light oil , combustion takes place at low temperaturein the range 150 300C

AdvantagesAdvantages

Source is available everywhere. Can be applied in tight reservoirs where water injectivity is low.

LimitationsLimitations

Controlling channeling of injected air is important becauseearly breakthrough of air reduces oil production periodsignificant

Tight reservoirs having induced fracture are not suitable forHPAI process

Case history of ISC process Indian scenario


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y p

Mar 1990 ISC Pilot Balol

Jan 1992 Semi-commercial Balol

Apr 1997 Phase-I (Commercial) Santhal

Oct 1997 Phase-I (Commercial) BalolMay 2000 Main (Commercial) Balol

Sep 2000 Main (Commercial) Santhal

Case HistoryCase HistoryIn-situ Combustion, Balol


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Depth 1000 m

Type Unconsolidated sand stone

Area 17 sq km

6 mPorosity 25-30%

Permeability 1-5 d

Dip 5Oil saturation 70

Pressure hydrostatic

Drive Active aquifer Oil viscosity 150-1500 cp

API 15

Envisaged 12Res. Temp. 70C


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Balol pilot started : March, 1990 Pilot area: 5.5 acres

Sustained combustion and productions from

producers lead to conceptluation and commercial inentire Balol

Considering similar characteristics, it was decided to

implement in Santhal field Commercial scheme started : 1997, Balol & Santhal

64 well have been ignited in both fields

A commercial scheme to be implemented to Lanwafield

Performance - Balol

N f Fl i ll 90


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No. of Flowing wells : 90

Air Injectors on stream : 21Air Injection rate, MMNm3/d (MMSCFD) : 0.60 (20)Oil rate, tpd (bopd) : 618 (4130)Water Cut, % : 58

0

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Water Cut

Commercialisation

Thermal EOR - World Scenario (Active Projects)


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Number of active thermal projectsCountry

Hot water Steam Combustion

USA 3 46 7Canada - 13 3

China - 17 1

Colombia - 2 -

India - - 3

Indonesia - 2 -

Trinidad - 8 -

Venezuela - 38 -

Total 3 126 14

Emerging technologies in EOREmerging technologies in EOR


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Emerging technologies in EOREmerging technologies in EOR

Low tension water flooding

Low salinity water flooding

AS alternate gas flooding

Microbial flooding

Possible EOR processesPossible EOR processesTight and light oil reservoirsTight and light oil reservoirs

High pressure air injection


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Gas injection Surfactant assisted gas flooding

Surfactant assisted water flooding

N2/Flue gas in deep light reservoir

Polymer flooding

ASP flooding/SP Flooding

Medium viscosity oil reservoirsMedium viscosity oil reservoirs

Surfactant flooding

Surfactant alternate alkali flooding

WAG/SWAG

Carbonate reservoirCarbonate reservoir

Alkali surfactant followed by Polymer

Alkali surfactant followed by Gas

Waxy crude reservoirWaxy crude reservoir

Before considering any process detailed laboratoryBefore considering any process detailed laboratoryinvestigation&pilotinvestigation&pilotis requis requ

ConclusionsConclusions

Right selection of EOR process and accurate knowledge


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Right selection of EOR process and accurate knowledge

about the reservoir holds key to success of EORprocess

Chemical EOR, gas injection and their combination

appears promising EOR process for Indian reservoir

MDT approach including geologist, geophysicist,

reservoir engineer, chemist, production and drillingengineers is needed for laboratory investigations,

designing, implementation and monitoring of an EOR

process Advances and better understanding in the area of

various EOR techniques

Contd..Contd..


67/95

Challenges are more but with sustainedefforts right solutions can be arrived

Meticulous monitoring of pilots andremedial measures are needed beforeimplementation on filed scale

In-house manufacture should beencouraged to develop and manufacturehigh performance EOR chemicals such as

polymers and surfactants Expertise of domain expert help whiledesigning and evaluation of EOR process


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Case history of chemical EOR (Indian scenario)Case history of chemical EOR (Indian scenario)



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Type of formation- Sandstone Thickness- 2-8 mts

Porosity- 24-32 % Permeability- 1500 md Temperature- 850C Depth- 1325 mts Pressure- 100 kg/cm2

Primary recovery 14.7% Oil viscosity- 20 cp

Drive Partial edge water Salinity of formation water 10000 ppm

yy

Characteristics of FieldCharacteristics of Field

Because of mobility contrast and low primary recovery, it was decided to

go for polymer flooding

Contd..Contd..


70/95

Based upon laboratory investigations pilot started in1985 inverted five spot

Extended pilot in 1993 4 injectors and 9 producers

After successful pilot test polymer flood on entirefield was commercialized in 1996

Project performance was reviewed in 2005

Redistribution of polymer injectors and adding moreunder polymer flood


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ObservationsObservations

Frequent injectivity decline observed inpolymer/chase water injectors

Preferential movement is part of reservoir

Bacterial activity

Remedial measures are taken to minimize aboveproblems

VirajViraj


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Formation Sandstone Thickness 16 mts

Porosity 25-30 % Permeability 4 to 9 Darcy Oil saturation - Temperature 810C Pressure - 135 kg/cm2 Oil viscosity 35-50cp Salinity 10000 ppm

Acid number 1.625 Drive mechanism active edge water drive Average water cut 85%

Contd..Contd..


73/95

Based on laboratory studies ASP pilot was designed

Pilot started in 2002 (inverted five spot with 4

injectors and 9 producers)

Polymer slug completed in March 2005 and chase

water was started and is continuing

OilViscosity

PoreVolume

OilRecovered

ChemicalsUS Chemical

Successful case studies of chemical EOR processes


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Field Region Start API

Viscosity

- cp Type

Volume

Chemicals

Recovered

% OOIP

US

Cost/bbl

Chemical

system

Adena Colorado 2001 43 0.42 Tertiary In progress $2.45 Na2CO3

Cambridge Wyoming 1993 20 25Secondar

y 60.40% 28.07% $2.42 Na2CO3

Cressford Alberta 1987

Secondar

y $2.25

Alkali andPolymer

Only

Daquing BS China 1996 36 3 Tertiary 82.10% 23.00% $7.88

NaOH -Biosurfactant

Daquing NW China 1995 36 3 Tertiary 65.00% 20.00% $7.80 NaOH

Daquing PO China 1994 26 11.5 Tertiary 42.00% 22.00% $5.51 Na2CO3

Daquing XV China 36 3 Tertiary 48.00% 17.00% $9.26 NaOH

Daquing XF China 1995 36 3 Tertiary 55.00% 25.00% $7.14 NaOH

Daquing Foam China 1997 NA NA Tertiary 54.80% 22.32% $8.01

ASPFoamFloodfollowingWAG

Daquing ScaleUp China ?? Reported to be Shut In Due to QC Problems with Surfactant

David Alberta 1985 23 Tertiary $0.80

Driscoll Creek Wyoming 1998 Acrylamid converted to acrylate - water cut lowered

Enigma Wyoming 2001 24 43Secondar

y In progress $2.49 Na2CO3

Etzikorn AlbertaCurrent In progress - Information not released

Field Region Start APIOilViscosity -

cp Type

Pore VolumeChemicals

Oilrecovered %OOIP

ChemicalsUSCost/bbl

Chemicalsystem

Contd..


75/95

Gudong China 1992 17.4 41.3 Tertiary 55.00% 26.51% $3.92

Isenhaur Wyoming 1980 43.1 2.8Seconda

ry 57.70% 11.58% $0.83

Alkali andPolymerOnly

Karmay China 1995 30.3 52.6 Tertiary 60.00% 24.00% $4.35

LagomarVenezuel

a 2000 24.8 14.7 Tertiary 45.00% 20.11% $4.80Single Well

Test

Mellot Ranch Wyoming 2000 22 23 Tertiary In progress $2.51 NaOH

Minas I Indonesia 1999 Micellar Polymer Failed when salinity of slug decreased

Minas II IndonesiaCurren

t Lignin II Surfactant - In progress - Information not released

Sho Vel TumOklahom

a ` 26.4 41.3 Tertiary 60.00% 16.22% $6.40

Low AcidNumber -Viscous

Bevery Hills California Surfactant Injectivity Test

Tanner Wyoming 2000 21 11 Secondary In progress $2.82 NaOH

West Kiehl Wyoming 1987 24 17 Secondary 26.50% 20.68% $2.13

West Moorcroft Wyoming 1991 22.3 20 Secondary 20.00% 15.00% $1.46

Alkali andPolymerOnly

White Castle Louisiana 1987 29 2.8 Tertiary 26.90% 10.10% $8.18

No

Poly

mer

Major challenges in Gas EORMajor challenges in Gas EOR


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j gj g

Availability of required quantity of gas

Depleted reservoirs attaining miscibility is an area ofconcern

Mobility control is another issue

Dipping reservoirs are needed

Immiscible process results in poor recovery

Presence of lighter hydrocarbons

Cost is high

WAG ProcessWAG Process Combines benefits of higher microscopic displacement efficiency of gas

and high macroscopic displacement efficiency of water leading to lower


77/95

g p p y g

ROS

Contact of unswept zone by segregation of gas to top and water tobottom

Good in reservoir with fining upward sand

Lower ROS in three phase zone due to gas trapping mechanism

Reduced mobility to both water and gas in three phase zone conditiondue to relative permeability hysteresis

Vaporization of oil due to mass transfer

Water reduces the mobility of gas and gas gets higher contact time withoil

WAG ratio 1:1 which can be tapered later on

Process does not allow uniform distribution of water and gas,particularly due to difference in viscosity of water and gas, gravityseparation of the component can occur, thereby decreasing theefficiency of the process

WAG is technoeconomially heavy

Immiscible WAG PilotImmiscible WAG Pilot

Reservoir parameters GS-11, a clastic light oil reservoir in Gandhar


78/95

Depth 2700m Temperature 1300C Thickness 5-6 m API Gravity

Reasons for selecting

Favourable mobility ratio for ideal water flooding High reservoir temperature rules out most of the chemical processes Availability of natural gas from deeper reservoir High miscibility process even with enriched gas

MMP 270 kg/cm2

(methane 70%) MMP 285 kg/cm2 (methane content 83%) Non availability of enriched gas/CO2 WAG combined benefit of water and gas

Laboratory findings

Water flooding 66% WAG 75%

ROS 12 % Details of Pilot

WAG started in 2006 as a normal 5 spot pattern Gas injection is 100000 m3/day Water injection is 600 m3/day

Performance - SanthalNo. of Flowing wells : 137Air Injectors on stream : 21


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j

Air Injection rate, MMNm3/d (MMSCFD) : 0.85 (30)

Oil rate, tpd (bopd) : 1086 (7200)Water Cut, % : 61

0

400

800

1200

1600

2000

Qo,tpd

0

20

40

60

80

100

WaterCut,%

Summary of EOR processes world wide

2-3 % of world production


80/95

Number of active EOR projectsCountry

Thermal Gas Chemical Other

USA 56 83 4 -

Canada 16 32 - -

China 18 - 18 2

Colombia 2 - - -

France - - 1 -

India 3 1 2 3

Indonesia 2 - 1 -

Libya - 1 - -

Mexico - 1 - -

Trinidad 8 5 - -

Turkey - 1 - -

UAE - 1 - -

Venezuela 38 9 2 1Total 143 134 28 6

As on 1.4.2004 : 311 active projects

Criteria for Selection ofCriteria for Selection of


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Crude oil:API : 8 to 20Viscosity : 40

Type of formation : Sand stone with high K & O

Av. Permeability : > 200

Depth, ft : 300 500Temp. of Res. : N.C.


82/95

Part IVPart IV

Microbial EOR

Microbial Enhanced Recovery ProcessesMicrobial Enhanced Recovery Processes

MEOR is family of microbial processes which involves


83/95

injection of microbes & nutrients to improve oilproduction from the well/ reservoir

It involves -- Injection of microbes/ nutrients in reservoir

-- Incubation

-- Growth, proliferation & generation of

metabolites

-- Mobilization of oil

Applied mostly

-- Huff-puff mode. -- Few case history are available where it has

applied in water injection mode

Microbial Products and Their ActionMicrobial Products and Their ActionImproves:


84/95

Acids

Gases

(CO2, CH4)

Solvents

Surfactants

Polymers

porosity permeability

Increase pore pressure. Oil swelling Viscosity reduction

Solubilize oil

Lowers interfacial tension

Mobility control

Microbial Vs Conventional EOR ProcessesMicrobial Vs Conventional EOR Processes


85/95

Conventional EOR processes are specific for aparticular reservoir and crude oil. Microbial processcan be applied in varied conditions

Microbial solution contains live micro organisms andcan transport themselves in different directions where

they are most needed

Problem of adsorption of chemicals is inherent part ofany conventional chemical process, which is least inmicrobial processes

Selection of MicrobesSelection of Microbes


86/95

Type of reservoir and petro-physical properties

Temperature and pressure

Property of crude oil and formation water Purpose for which microbes are being used

Microbial Processes DevelopedMicrobial Processes Developed

Mi bi l EOR


87/95

Microbial EOR

IRSM1 & IRSM2 bacterial consortia active upto 65C

S-2 bacterial consortium active upto 90C NJS7- 91 & NJS4- 96 bacterial consortia active at 91

and 96C Stimulation of In-Situ microbes

R 2 & HS4-2 Biosystems producing biosurfactants

Bacterial Consortium SBacterial Consortium S--2 (2 (UptoUpto 9090 C)C)

High Temperature Microbes : S-2

Micro- photographCharacteristics


88/95

The consortium is THBA

pH Tolerance : 4 9

Cell Morphology : small cocci ,shortrods & size- 0.1- 1.3 micron

Useful Metabolites: Volatile Fatty

acids, Carbon dioxide Energy Source : Molasses (3%)

Incubation : 21 days

Pathogenicity : Non-pathogenic

Applied : 30 wells (39 jobs)

Well Selection Criteria for Application of MEOWell Selection Criteria for Application of MEOR

Parameter Recommended Range


89/95

Type of formation Sand stone (preferably)

Temperature < 90C

Pressure, Kg/cm2 < 300 Kg/cm2

Reservoir rock permeability >50 md

API gravity of crude oil > 20Viscosity of oil < 20 cp (under reservoir conditions)

Water cut 30-90 %

pH 4-9 (preferably 6-8)

Residual oil saturation > 25 %Salinity as NaCl


90/95

Applied in 43 wells of 4 different fields of ONGC

& 8 wells of OIL, Duliajan.

Total Oil gain around 43,000 m3.

Gain around 1000 m3 per well per job.

Average life cycle 6-8 months.

Success ratio 70%.

Performance of MEOR job in SB # 36


91/95

:

Pre job: Post job

Ql: 14.3 Ql: 19-31

W/C: 78% W/C: 42-80%

Q0: 3.1 Q0: 6.6-14.5

Incrementaloil gain, m3

2300

0

5

10

15

2 0

2 5

3 0

3 5

4 0

Date

OilRate(m3/d)

0

10

2 0

3 0

4 0

50

6 0

70

8 0

9 0

100

WaterCut(%)

MEOR

ob

Wellclosed

Oil Rate

Water Cut

Date of MEOR job:

22.01.2004

Status of various EOR ProcessesStatus of various EOR ProcessesISC processISC process

CommercialCommercial

Balol Phase I


92/95

Balol Phase-I Santhal Phase-I

Balol Main

Santhal Main

To be commencedTo be commenced

Lanwa ISC project

Gas injection processGas injection process

CommercialCommercial GS-12, miscible gas injection

Ongoing pilots (WAG)Ongoing pilots (WAG)

GS-11, Gandhar

Pilot to bePilot to be intiatedintiated(WAG)(WAG) GS-4 and GS-9 sand

Ongoing SWAG pilotOngoing SWAG pilot

MHS, SH platform

Sanand polymer flood

Chemical EORChemical EOR

CommercialCommercial

To be commencedTo be commenced

Kalol ASP pilot

Ongoing ASP pilotOngoing ASP pilot

Viraj ASP pilot

Jhalora ASP pilot

Microbial System For High TemperatureMicrobial System For High TemperatureReservoirs Above 90Reservoirs Above 90cc

NJS7NJS7 91 and NJS491 and NJS4 96 were isolated from formation fluids96 were isolated from formation fluids


93/95

NJS7NJS7--91 and NJS491 and NJS4--96 were isolated from formation fluids96 were isolated from formation fluidsofofNandejNandej andand SobhasanSobhasan wells.wells.

Both the isolates are Anaerobic

Hyperyper thermophilicthermophilic: grow at 91 & 96: grow at 91 & 96 CC

HalophilicHalophilic : grow in 7% and 4% salinity: grow in 7% and 4% salinityrespectively.respectively.

Non-pathogenic

Optimum incubation period : 2-3 weeks

Based on surface tension reduction, yield stability and corBased on surface tension reduction, yield stability and cor

flooding experiment two consortia selected:flooding experiment two consortia selected:HS4HS4 2 & R2 & R 22

Selection Of ConsortiaSelection Of Consortia


94/95

flooding experiment, two consortia selected:flooding experiment, two consortia selected:HS4HS4--2 & R2 & R--22

Results:Results:

Surface tension : 35 dynesSurface tension : 35 dynesSurfactant product : 1 gm/Surfactant product : 1 gm/litrelitre

CMD : 80CMD : 80

Additional oil recovery over OIIP(%) :Additional oil recovery over OIIP(%) :

19 for HS419 for HS4--22

08 for R08 for R--22

IFT reductionIFT reduction ::

0.064 dynes/m for HS40.064 dynes/m for HS4--22

0.535 dynes/m for R0.535 dynes/m for R--22

Future ActivitiesFuture Activities


95/95

Isolation of thermophilic bacteria for profile

modification.

Isolation and identification of bacteria for

enhancing oil recovery in water flood mode.

Development of suitable bacteria for heavy crude.