The aim of this project is to investigate the oil production in fractured reservoirs and to have an understanding of recovery mechanisms and all the methods that lead to improvement of the production in fractured reservoirs especially the EOR processes and to determine the advantages and limitations of fractures during EOR process.

1. Kurdistan Regional Government
Presidency of Minister Council
Ministry of higher education
And scientific Research
koya university
Faculty of Engineering
Department of Petroleum
Prepared by :
Bakhtyar Abdulstar
Huner Mahdi
Muhammad Faisal
Improving Oil Recovery In
Fractured Reservoirs
supervised by: Mr. Ayoub Hikmat
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2. Outlines:
 Aim
 Recovery mechanisms
 Recovery types
 Types of EOR
 Case studies
 Conclusion
 Recommendations
 References
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3. The aim of this project is to investigate the oil production in
fractured reservoirs and to have an understanding of recovery
mechanisms and all the methods that lead to improvement of
the production in fractured reservoirs especially the EOR
processes and to determine the advantages and limitations of
fractures during EOR process.
Aim: 3

4. Recovery Mechanisms in Fractured Reservoirs
 fluid expansion
 capillary imbibition
 diffusion
 gravity-controlled displacement (Gong, 2017)
In fractured reservoirs there are four principal recovery
processes:
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5. Recovery in fractured reservoir
 It is estimated that more than 60% of the world's oil reserves are held in
carbonate reservoirs, and a significant part of these reservoirs are
naturally fractured. (Gong, 2017)

(researchgate.net,2017)
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6. Primary Recovery:
The underground pressure in the oil reservoir is sufficient, then this pressure will force the oil to
the surface
 Water Drive (70 to 80%)
 Solution gas drive (10 to 30%)
 Gas Cap Drive
 Gravity Drainage
 Fluid and Rock Expansion
Usually, about 20% of the oil in a reservoir can be extracted using primary recovery methods.
(hatiboglu, 2006)
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7. Secondary Recovery:
 Secondary oil recovery uses various techniques to aid in recovering oil
from depleted or low-pressure reservoirs
(slideshare.net,2015)
 primary and secondary recovery generally allow 25% to 35% of the
reservoir's oil to be recovered (hatiboglu, 2006)
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8. Secondary recovery techniques:
 pumps
 electrical submersible pumps
Others for increasing pressure:
 water injection,
 natural gas reinjection (hatiboglu, 2006)
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9. Tertiary Recovery
 Enhanced Oil Recovery (EOR)
(researchgate.net,2015)
 increasing the displacement efficiency
 Increasing sweep efficiencies
 Increasing both displacement and sweep efficiencies
 Allows additional 20% to 30% of the oil in the reservoir to be extracted (hatiboglu, 2006)
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10. Enhanced Oil Recovery (EOR):
 Miscible: 1) Carbon Dioxides Flooding(Co2) 2) Nitrogen and Flue Gas Flooding, 3) Enriched
Hydrocarbon Gas Flooding
 Thermal: 1) Steam Flooding 2) Fire Flooding
 Chemical: 1) Surfactant flooding, 2) Polymer Flooding 3) Alkaline or Caustic
Flooding(Donaldson, 1989)
EOR classification :
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11. Miscible:
• Nitrogen flooding
• 5,000 feet depth
• API gravity higher than 35 degrees
•Water slugs are injected alternately with the nitrogen to increase the sweep efficiency and oil
recovery (Arthur J. Kidnay, 2011)
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(nwairservices.100wd.net,2014)

12. Miscible:
 reservoirs deeper than 2,000ft.
 Reinjection
 Availability of CO2 (S. Lee, 2013)
• CO2 injection
• (neori.org,2016)
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13. Thermal recovery:
Thermal recovery methods are generally applicable to viscous, heavy oil crudes, and involve the
implementation of thermal energy or heat into the reservoir to raise the temperature of the oil and
reduce its viscosity(Donaldson, 1989)
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1) Steam Flooding
2) Fire Flooding

14. Thermal recovery:
Steam Flooding:
In a steam flood, sometimes known as a steam drive, some wells are used as steam injection wells and
other wells are used for oil production. Two mechanisms are at work to improve the amount of oil
recovered
The first is to heat the oil to higher temperatures and to thereby decrease its viscosity so that it more easily flows
through the formation toward the producing wells
A second mechanism is the physical displacement employing in a manner similar to water flooding, in which oil is
meant to be pushed to the production wells.
A-Steam Stimulation
B-Steam drive
• Methods steam flooding:
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(Donaldson, 1989)

15. Thermal recovery:
 •Recoveries of additional oil have ranged from 0.21 to 5.0 bbl. of oil per barrel of steam injected.
(Donaldson, 1989)
A-Steam Stimulation
This method, also known as the Huff and Puff method, consists of 3 stages:
• 1)injection
• 2)soaking
• 3) Production
The process involves
–Injection of 5000–15,000 bbl. of high quality steam.
–Shutting-in the well (from 1-5 days) to allow the steam to soak the area around the injection well
–Placing the injection well into production
15

16. A-Steam Stimulation 16
(independent.com, 2017)

17. Thermal recovery:
B-Steam drive:
It is like a conventional water flood. Steam is injected into several injection wells while the oil is
produced from other wells. (Diff. from steam stimulation)
• Some thermal energy is lost in heating the formation rock and water
• The steam moves through the reservoir and comes in contact with cold oil, rock, and water.
• As the steam comes in contact with the cold environment, it condenses and a hot water bank is formed. This
hot water bank acts as a water flood and pushes additional oil to the producing wells. (Donaldson, 1989)
17

18. B-Steam drive: 18

19. Thermal recovery
 dry combustion process
 –Injection of steam of oxygen enriched air
 –Propagation of flame front through the reservoir heating oil.
In dry-situ combustion(fire flooding)
combustion process –Ignition of crude oil down hole
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(S. Lee, 2013)

20. Thermal recovery
 Beginning as a dry process
 Once flame front is established, the oxygen stream is replaced by water
 Water meets hot zone left by combustion front
 Turns into steam, and aids the displacement of oil
In Wet-situ combustion
Wet combustion process
combustion process –Ignition of crude oil down hole
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(S. Lee, 2013)

21. chemical flooding
 The injection of various chemicals, usually as dilute solutions, have been used to aid
mobility and the reduction in surface tension.
 Injection of a dilute solution of a water soluble polymer to increase the viscosity of the
injected water can increase the amount of oil recovered in some formations
injection alkaline and soap-like substances are used to reduce surface tension between oil and
water in the reservoir, whereas polymers such as polyacrylamide or polysaccharide are
employed to improve sweep efficiency.
1) Surfactant flooding, 2) Micellar Polymer Flooding, 3) Polymer Flooding 4) Alkaline or
Caustic Flooding
chemical flooding Types:
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(Schramm, 2000)

22. Polymer flooding
 PAM makes the water "gel" greatly improving the production of oil. The water injected
becomes more "viscous" or thick, much like a gel and is particularly beneficial in heavy oil
recovery
the polymers used reduces the "surface tension" between the oil and the oil-containing rock within the
oil reservoir, "freeing" the trapped oil making it easier to flow to the production well(s).
Benefits:
• Improved oil recovery
• Increased "sweep efficiency"
• Significantly less water required when compared with typical waterflooding & steam
injection
22
(polymerflooding.com, 2013)

23. Polymer flooding
In water injection the fingering effect reduce sweep efficiency. But in polymer flooding this finger effect is
not present. Fingering causes to flow water along with oil through production line (polymerflooding.com,
2013)
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Polymer injection (studyblue.com, 2016)

24. Microbial injection
bacteria inoculated with water in to the well will progress into high-permeability zones at first. Then at a later stage
they will grow and occlude those zones due to their size and the negative charge on their cell surface. This
scenario helps to increase the sweep efficiency, and thus a more efficient oil recovery can be achieved (Biji Shibulal,
2014)
(lizinan.wordpress.com, 2011)
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25. Other Upcoming Technologies
Nano fluid can be used to change properties of reservoir such as:
 Fluid-fluid properties: interfacial tension, viscosity
 fluid-rock properties: contact angle, relative permeability
 Thermal conductivity of injection fluid (Petroleum, 2017)
-Nano-technology
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26. Case studies
26

27. (Nano fluid in Egypt)
compare between using water flooding and Nano fluid flooding as EOR methods
• using water flooding to displace the oil in place recovered 36% of IOIP at the breakthrough point while
the Nano fluid flooding recovered 67% of IOIP at the breakthrough point.
• This is an evidence for the ability of the Nano fluid to displace the oil better than the water
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28. EOR in a fractured reservoir in Iran:
 a naturally fractured reservoir in south western of Iran
 90 km in length and 16 km width at the surface
 Depth of 1000 m jahrum and 2000 m sarvak formation
 has a total net pay thickness of 312 ft
 and contains 0.832×10^9 bbl. original volume of oil in place
(Arash Kamar, 2014)
(researchgate.net, 2014)
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29. Quick screening by(EORgui 1.0 software, 2013):
 The results show that the most appropriate method for implementation in the
reservoir is steam flooding method.
(researchgate.net, 2014)
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30. Simulation:
 Steam is injected 2000 bbl/day
 Injection pressure is 1800 psi
 Area of 40 acres
 OOIP in 40 acres is 4,651,000 bbl
 Maximum recovery is 3,835,100 bbl
(researchgate.net, 2014)
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31. CONCLUSION:
 production strategy, reservoir stimulation, type of completion, etc. are
important IOR
 economics and environmental effects need to be considered
 Fractures have risks and benefits in EOR
31

32. CONCLUSION:
 Risks:
(uis.no, 2013)
32

33. CONCLUSION:
 benefits:
 For water and surfactant imbibition processes,
large fracture areas are critical to making the
process work
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34. CONCLUSION:
 The below figure shows the most used EOR methods worldwide.
(slideshare.net, 2013)
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35. Recommendations:
 EOR has environmental effects. So they need to be considered during screening
process.
 There are many simulations for reservoir engineering:
 BOAST (used by the U.S department of energy), MRST (MATLAB simulation
toolbox), OPM, Schlumbergers INTERSECT and ECLIPSE, CMG, Tempest MORE,
ExcSim, Nexus, ResAssure, tNavigator, FlowSim, ReservoirGrail, Merlin (used by
Bureau of Ocean Energy Management).
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36. Used references:
 Gong, J., 2017. Earth Doc. [Online] Available at:
http://www.earthdoc.org/publication/publicationdetails/?publication=88000 [Accessed 23 5 2017].
 hatiboglu, C. u., 2006. Primary and Secondary Oil Recovery From Different-Wettability Rocks by Countercurrent
Diffusion and Spontaneous Imbibition. [Online] Available at: https://www.onepetro.org/conference-paper/SPE-
94120-MS [Accessed 23 may 2017].
 Donaldson, L., 1989. Enhanced Oil Recovery, II: Processes and Operations. 2 ed. s.l.:Elsevier.
 Arthur J. Kidnay, W. R. P. D. G. M., 2011. Fundamentals of Natural Gas Processing. 2 ed. s.l.:CRC Press.
 Biji Shibulal, S. N. A.-B., 2014. Microbial Enhanced Heavy Oil Recovery by the Aid of Inhabitant Spore-Forming
Bacteria: An Insight Review. [Online] Available at: https://www.hindawi.com/journals/tswj/2014/309159/
[Accessed 23 5 2017].
 Arash Kamar, A. H. M., 2014. Handbook on Oil Production Research. 1 ed. Paris: Nova Science Publishers, Inc..
 DOE/NETL, 2011. Enhanced Oil Recovery Environmental Benefits. [Online] Available at:
https://www.c2es.org/initiatives/eor/environmental-benefits [Accessed 23 5 2017].
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37. Thank you !!
Any question ?
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