This document provides an overview of thermal enhanced oil recovery (EOR) methods for heavy oils. It discusses the basic mechanisms and screening criteria for steam injection, steam assisted gravity drainage (SAGD), hot water flooding, and combustion methods like in-situ combustion (ISC) and high pressure air injection (HPAI). Case studies on SAGD and HPAI are presented. Thermal EOR aims to increase reservoir temperature and reduce oil viscosity for improved production rates. Proper screening of reservoir properties like depth, viscosity, permeability is required to select the optimal thermal method.

1. EOR Thermal Methods
[Heavy , viscous crude]
Target : Increase reservoir temperature
of the oil and reduce its viscosity.

2. Agenda
Introduction to EOR Thermal Methods
Basics of EOR Thermal Methods
Basic mechanisms of steam and air injection
Brief Summary of Screening Criteria for EOR Thermal
Overview of EOR Thermal Methods
Field Case: HPAI in Cedar Hills
Final Comments

3. Introduction to EOR Thermal Methods
Estimated Heavy Crude Oil World Reserves
Key factors in thermal EOR :
– Depth – Viscosity – Permeability

4. Comparison of Heavy Oil Data (some fields

5. Thermal Methods
Steam Flooding (SF) - Continue (paterns
- Alternate (same well used to inject and produce)
Hot Water Flooding (HWF) – reduction of oil viscosity
Steam Assisted Gravity Drainage (SAGD) - horizontal wells mainly
-one injector one producer
Combustion in Situ (CIS) – through air injection a combustion front and
chemical reactions that move oil to the producers
High Pressure Air Injection (HPAI) - interfacial tension changes, oil swelling
and reservoir re pressurization

6. Steam Flooding (SF) - Continue (patterns)
Rock and fluid properties, heterogeneities as directional l distribution of K
and porosity, lack of lateral continuity, etc are key factors to take in account.
• 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, then it condenses and a hot water bank is formed. This hot
water bank acts as a water flood and pushes additional oil to the producers

7. Steam Flooding (SF) - Continue (patterns)
Mechanisms of this process
– include thermal expansion of the crude oil,
– viscosity reduction of the crude oil,
– changes in surface forces as the reservoi rtemperature increases,
– and steam distillation of the lighter portions of the crudeoil.
• This application is limited due to loss of heat energy. In deep wells,
steam will be converted to liquid water
•
Oil recoveries have ranged from 0.3 to 0.6 bbl of oil per barrel of
steam injected.(rule of thumb)

8. Steam Injection Calc

9. Basic of Steam Injection - Alternate
steam huff and puff, steam soak, or cyclic steam injection
• 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.
• The length of the production period is dictated by the oil production
rate
The cycle is repeated as many times as is economically feasible.
•
Mechanisms of this process include1)
• Reduction of flow resistance by reducing crude oil viscosity.
• Enhancement of the solution gas drive mechanism by decreasing
the gas solubility in an oil as temperature increases.
• Recoveries of additional oil have ranged from 0.21 to 5.0 bbl of oil
per barrel of steam injected.

10. Basics of Steam Injection - Stages
Adapted from Chandran Udumbasseri

11. Basics of Steam Injection - Criteria
Values are not mandatory .
There are recommended values for key parameters.

12. Cyclic Steam Injection Calc
0
50
100
150
200
250
300
350
1
10
100
0 200 400 600 800
Temperature(F)
LiquidRate(bbl/day)
Time (days)
Cyclic Steam Results
Water Oil Temperature
Cycle 1 2
Steam injection rate per cycle (bbl/d , m3/d) 900 900
Duration of injection period per cycle (days) 7 7
Duration of soak period (days) 7 7
Downhole steam temperature (f or c) 350 350
Downhole steam quality (fraction) 0.50 0.50
Time limit of production per cycle (days) 120 120
Depletion index limit for each cycle 3 3
Initial bottomhole flowing pressure (psi or kpa) 110 110
Half life constant for bottomhole pressure decline (days) 5 5
Lower limit of bottomhole pressure (psi or kpa) 17 17
Maximum liquid production allowed per cycle (bbl/d or m3/d) 800 800
Downhole steam pressure (psi or kPa) 137.1 137.1
Oil viscosity at steam temp (cp) 3.9 3.9
Steam zone thickness (ft or m) 44.1 44.1
Steam zone volume (ft3 or m3) 174,529.4 190,677.4
Steam zone radius (ft or m) 17.7 18.6
Viscosity factor 1.0 1.0
Time since starting project (days) 121.0 246.0
Cumulative oil production (bbl) 1,335.0 1,829.4
Oil recovery this cycle (% OIP) 0.5 0.2
Total oil recovery (% OIP) 0.5 0.7
Cumulative water injected (bbl) x 6,300.0 12,600.0
Oil-steam ratio 0.2 0.1
Water remaining in reservoir (bbl) 82,094.4 69,953.5
Average reservoir temperature (deg F) 132.2 136.1
Heated zone radius (ft) x 17.7 18.6
Steam zone thickness (ft) x 44.1 44.1
Total heat injected (Btu) x 1.51E+09 1.51E+09
Heat remaining in heated zone (Btu) 1.31E+08 1.68E+08
Heat loss during injection (Btu) x 9.39E+07 9.39E+07

13. Approximate RF by Mechanisms
in Heavy Oils

14. Steam Assisted Gravity Drainage (SAGD)

15. SAGD Steam {Schematic} Chamber
Reduced viscosity and horizontal well allow practical rates without
steam production (no coning)
Steam replaces produced oil and raises pressure at top to allow
flow in same cases.

16. Main Reservoir Properties of International
SAGD Projects ( as of 2011)

17. (SAGD) Scheme

18. SAGD Numerical Simulation:
Impact of Reservoir Permeability (Kv/Kh = 0.6)

20. Hot Water Injection
(qualitative contributions of different mechanisms to recover
due to hot water injection)

21. ISC : Air Injection (simulation data)
Typical Oxidation Temperature vs Recovery
To obtain high oil recoveries in HPAI and ISC, reactions must be in bond
scission - CO2 generating mode.
Aproximately 10 – 15 % of OIP will be burned

22. ICS Process Scheme
The reduced-viscosity oil draining into the horizontal production well
under force of gravity.
Mobil Oil Corporation
At the lower portion
At the upper
zone , O2
enriched gas
is injected and
ignited
Once combustión
front is created , it
moves downwardly
toward the
horizontal well

23. Scheme of Oxygen Consumption Profile
The process is typically used for deep, tight, relatively light-oil reservoirs
where water injectivity is low.

24. Screening of EOR Thermal Methods

25. Geologic Screening Criteria: Heterogeneity
possible
Adapted from Tyler & Finler

26. Screening Criteria for Steam Injection
Methods and Horizontal Wells

27. Overview of EOR Thermal Methods

28. Example of RDP under Steamflooding:
Mukhaizna Heavy Oil Field, Oman

29. Overview of EOR Thermal Methods SAGD

30. High Pressure Air Injection (HPAI):
Cedar Hills, North Dakota)
Why High Pressure Air Injection?

31. High Pressure Air Injection (HPAI):
Cedar Hills, North Dakota)

32. Final Comments

33. Final Comments (II)

34. Note
Data presented here were provided by C.
Norman mainly.
Other sources are lebeled in each slide