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