Enhanced Oil Recovery
Ken From CEO, Petroleum Technology Research Centre
Michael J. Monea
President, BHP Billiton SaskPower CCS Knowledge Centre
ENHANCED OIL RECOVERY
AGENDA Introduction Primary Production Secondary Production Enhanced Production Thermal CO2
Concluding Remarks
OIL RESERVOIR
• Oil Pool ? • Petra=Rock
Oleum=Oil • A petroleum
reservoir is a rock formation that holds oil and gas
OILFIELD PRODUCTION - LIFECYCLE
• Primary Production - Natural depletion of the reservoir
• Secondary recovery – putting energy back into the reservoir
• Enhanced Oil Recovery – changing the chemical and physical properties of reservoir fluids
Reservoir energy continues to decline until insufficient energy exists to force enough oil into the well to warrant continued production.
INCOMPLETE OIL RECOVERY
Main reasons for incomplete oil recovery • Heterogeneity exists at many
levels. • Unfavourable mobility ratio. • Capillary trapping.
(Coderre et al, 2012)
HOW TO MAXIMIZE RECOVERY
• Need a clear understanding of hydrocarbon system
• Well placement – number and location require reservoir knowledge/modelling (scale hundreds to thousands of metres)
• Oil recovery process rock/fluid interactions (scale to tens of metres)
• Oil displacement phenomena (scale micrometers to metres)
SECONDARY RECOVERY
• Waterflooding most common
• Simplicity • Availability • Cost
• Efficiency determined by fluid/rock properties, reservoir heterogeneity and placement of wells
• Optimized traditionally by updating reservoir models using historical data
SECONDARY RECOVERY – WATERFLOOD
Water flood technology uses water to get additional oil out of a reservoir. Viscous Fingering causes uneven sweep.
SECONDARY RECOVERY -- EOR
Polymer is a gel material that is added to the water to increase viscosity and further improve results of the water flood.
ENHANCED OIL RECOVERY
• Interact with the rock/fluids to create favourable recovery conditions.
• Oil viscosity reduction • Extraction of oil with a
solvent • Alter capillary and
viscous forces between the oil, injected fluid, and the rock surface.
• Increase sweep efficiency • Micro and macro
ENHANCED OIL RECOVERY – THERMAL METHODS
• Raise the temperature of the oil and reduce its viscosity
• Applicable to heavy viscous crudes
Steam Assisted Gravity Drainage SAGD: Two horizontal wells are drilled, one a few meters above the other, and steam is injected into the upper one.
CASE STUDY – THERMAL METHODS KERN RIVER
Kern River oil is characteristically heavy and sour with an API of 13.4 degrees and a sulfur content of 1.2 percent
ENHANCED OIL RECOVERY – SOLVENT INJECTION METHODS
• A solvent can mix with the oil, form a homogeneous mixture, and carry the oil away from the reservoir.
• CO2, propane, methane……
CO2 Injection • Is miscible with crude oil • When the injected CO2 and
residual oil are miscible, the CO2 dissolves in the oil, it swells the oil and reduces its viscosity
Diagram courtesy of DOE
Fig.1) Hexane in Heavy Oil - Miscible
Fig. 2) Propane in Heavy Oil- Soluble
Miscibility refers to whether a solvent can mix with oil and have no clear interface between them. (Fig.1)
CO2 in heavy oil is a solvent as it dissolves and changes the oil properties. But it is immiscible since there will be an interface between them. (Fig. 2) Thus a potential for trapping due to capillary forces. In conventional oil CO2 is a solvent and is miscible, meaning there is no clear interface between the gas and oil. CO2 can displace oil without any capillary trapping of oil. Although miscible, we are still pushing a liquid with a gas so even without a clear interface the system is unstable. The WAG process fixes the viscosity ratio but unfortunately introduces an immiscible phase (water) back into the system so once again we get trapping.
SOLUBILITY - MISCIBILITY
(Source: PERM Inc)
CASE STUDY – WEYBURN ENHANCED OIL RECOVERY Largest CO2 EOR project in Canada • OOIP 1.4 Bbbls • 160 Mbbls incremental Outstanding EOR response World’s largest geological CO2 sequestration project • 30 million tonnes stored
to date
WEYBURN OIL PRODUCTION
Midale Anhydrite
Oil & CO2 CO2
CO2 & Oil Oil & Water
Frobisher
Vuggy
Midale Anhydrite
Frobisher
Hz CO2 Injector
Marly
Vuggy
Vertical Producer Vertical Water
Injector
Water
Marly
CO2
Hz Producer
RESERVOIR INJECTION AND PRODUCTION
Reservoir heterogeneity results in complex well geometry and production methods.
RELATIONSHIP OF PURCHASED CO2 TO RECYCLED CO2
IMPACT OF CO2 FLOOD WEYBURN – STEELMAN
COMPARING CO2 – EOR TO “REGULAR” OIL
NEXT GENERATION OF CO2-EOR
Barriers to be solved *
Conformance – address the geological constraint heterogeneity.
Operating Strategies – where is the remaining oil?
Viscosity control – CO2 is less viscous, improved mobility control to avoid bypassing oil.
CO2 control – inject more CO2 without thief zone channeling.
Low pressure reservoirs – near miscible CO2 strategies. * - Vello Kuuskraa
CURRENT RESEARCH EOR
IOR and production optimization • Infill drilling • Targets identified
with 4D seismic and reservoir characterization
• Waterflood
EOR Measures • Thermal methods • Miscible gas
injection • CO2 injection • Surfactant flooding • Microbial EOR
CONCLUSIONS
• Frontier technique, despite many years of pilot wells and projects. • EOR operations require much higher precision than primary production:
project outcomes have an enormous dispersion with a high number of failures and some very successful cases (in the 30% to 50% range increase).
• EOR remains expensive: depending on project complexity and field size, the costs range from $10 to $80 per barrel.
• EOR is considered a technological frontier, especially for chemical methods. Indeed, EOR faces technical challenges include the following:
• Understanding static and dynamic reservoir characterization for correct assessment of fluid choice and injection well design and configuration
• Planning for the production and transport logistics for these fluids • Awareness of environmental constraints and reservoir life-cycle
limitations • Correct use of reservoir surveillance technologies
Complex technical challenges unique to each reservoir and type of EOR method.
Questions?
Thank You