1. CHEMICAL ENHANCED OIL RECOVERY
SUPERVISED BY MR. ABDULSALAM DANESHVAR
• AHMED TAHA HASAN
• ADAM OMAR
• AHMED HAMIDADEEN
• SOZ KHALID
UNIVERSITY OF ZAKHO
DEPARTMENT OF PETROLEUM ENGINEERING
4. • There are FOUR common types of chemical EOR methods namely:
1. Polymer Flooding.
2. Surfactant Flooding.
3. Alkaline Flooding.
4. Alkaline-Surfactant-Polymer (ASP) Flooding.
5. • To understand each method of chemical EOR, Advantages, disadvantages,
Injection process of chemicals into the formations and suitable conditions to
be applied have to be considered.
• To do chemical flooding in EOR, new wells have to be drilled for injection.
7. Mechanism
Injecting of chemical materials into the reservoir (polymer) in order to stop or
reduce water production by increasing its viscosity and there for reduce the
mobility ratio and enhance oil production.
8. • The description of the process is to inject polymer into the
formation, followed by water injection for the purpose of sweep
efficiency where it acts like a piston, polymer has the ability to
create oil bank to increase oil recovery.
• Polymer injection to control mobility ratio, water injection to
improve the sweep efficiency.
9.
10. • If water is only injected and due to reservoir
heterogeneity, the swept area will be less and but by
adding polymer the mobility is controlled.
11. Advantages
• Reducing water production by increasing its viscosity.
• Mobility control and flow pattern control.
• Sweep efficiency improvement.
• Lower cost compared with other chemical EOR methods.
• Recovery factor RF increases.
12. Disadvantages
• High water salinity (if it is more than 100,000 ppm) it changes
and reacts with the polymer composition leads to adsorption.
• Fracture presence leads to loosing of polymers into the
adjacent formations.
• Presence of clays and strong aquifer results in polymer
adsorption.
14. Mechanism
• It stands for Surface active agents.
• It is the injection of surfactant into the formation
targeting the surface between oil-water to break the
attractive forces between them (IFT) by producing
soaps at the contact reducing residual oil saturation in
addition to wettability change from oil wet to water
wet, followed by polymer injection to enhance the
sweep efficiency and control the mobility as well as to
stabilize the flow pattern.
15.
16.
17. Usually Co-solvents such as alcohol (low molecular weight)
are injected with surfactant:
• In many surfactant systems high viscosity liquid
crystals, emulsions and gels are observed alcohol is
used to break it.
• The optimum salinity can be adjusted by alcohol.
• Alcohol can eliminate the polymer-surfactant
incompatibility.
18. Advantages
• Reduce IFT and work as emulsifier between oil and
water.
• Sor reduction to a very minimum value, which
immediately leads to increase in the recovery factor.
• Wettability change from oil to water wet.
• Trapped (bypassed) oil is produced.
• Injection of polymer leads to pattern flow stabilization
and mobility control.
19. Disadvantages
• Complex process.
• Expensive compared to alkaline and polymer.
• Incompatibility between surfactant-polymer in case of
no co-solvent is used.
• Degradation of surfactant and polymer in case of high
reservoir temperature.
• Strong aquifer leads to both surfactant and polymer
adsorption.
20. Conditions to be Applied
• High remaining oil (Sor).
• Relatively homogeneous formation with no fractures is
preferred.
• High WOR but not excessive < 10.
• Low reservoir temperature to avoid surfactant
degradation.
• Weak to moderate aquifer strength to avoid surfactant
adsorption in the formation during the flooding
process.
22. Mechanism
• Alkaline or caustic flooding is another method by which
oil displacement efficiency can be improved.
• The basic alkaline flooding process starts with injection
of alkaline solution of about 10 to 30 percent PV pore
volume.
• Then followed by injection of a polymer slug behind the
alkaline solution to control mobility.
• lastly followed by water injection to improve sweep
efficiency.
23.
24. • The reaction between alkaline and formation oil results
in soaps production at the contact between oil-water
phases, there for IFT is reduced as well as Sor by
producing more trapped oil all of that happens due to
in-situ production of surfactant.
• Alkaline flooding is used in case of high acidity oil.
25. Advantages
• IFT reduction by producing soaps at the contact
between oil and water where oil contains high amount
of acids.
• Sor reduction due to more oil production and RF
increases.
• Mobility reduction, sweep efficiency enhancement and
pattern flow control due to using of polymer injection
behind alkaline flooding.
• Simple and cheap EOR method.
• Wettability change from oil to water wet due to the in-
situ production of surfactant.
26. Disadvantages
• Low recovery factor compared to other chemical EOR
methods.
• Degradation of alkaline in case of high reservoir
temperature.
• Alkaline adsorption in case of strong water aquifer.
27. Conditions to be Applied
• High acid content in oil reservoir.
• High remaining oil Sor.
• Low clay content.
• Low reservoir temperature to avoid alkaline
degradation.
• Weak to moderate aquifer strength to avoid alkaline
adsorption.
29. Mechanism
• ASP stands for Alkaline-Surfactant-Polymer flooding.
• it is the injection of a mixture contains the three
chemical EOR methods.
• The mixing process is usually prepared at the surface in
addition to adding water to the mixture, then it is
injected into the reservoir in order to enhance the oil
production and increase the recovery factor.
30.
31. • Alkaline is used to reduce IFT by producing soaps at
the contact between oil-water phases, then followed
by surfactant flooding which is used to reduce Sor as
well as change the wettability from oil to water wet,
polymer is used to control the flow patterns in case of
reservoir heterogeneity is existed and water is used to
improve the sweep efficiency.
32. Advantages
• High recovery factor since all of alkaline, surfactant
and polymer are used.
• Wettability change from oil to water wet.
• Reduce Sor to the minimum values.
• Improve the sweep efficiency by injecting polymer.
• Less adsorption in ASP process.
33. Disadvantages
• Incompatibility between polymer, alkaline and
surfactant in case of the unstable mixture.
• Very high cost compared to other EOR methods due to
use ASP then polymer an lastly water injection.
• Complex process, surface preparation problem and
mixture stability.
34. Conditions to be Applied
• High values of remaining oil volume Sor.
• Weak to moderate aquifer strength.
• Low reservoir temperature.
• Light to intermediate oil is favorable.
• Low clay content to avoid chemical adsorption.
35. The total acid number (TAN) is a measurement of
acidity that is determined by the amount of
potassium hydroxide KOH in milligrams that is
needed to neutralize the acids in one gram of oil
It is an important quality measurement of crude oil.
It is usually the naphthenic acids in the crude oil that
causes corrosion problems.
The values of TAN is still not acidity oil unless it
reaches 3-4 mg KOH/g of oil.
Total Acid Number
