Oil, south-eastern Saskatchewan, discovered in 1954

EnCana's Weyburn oilfield operation covers 70 square miles and is one of the largest medium-sour crude oil reservoirs in Canada, containing approximately 1.4 billion barrels of original oil in place. It is also the world's largest greenhouse gas sequestration site.

Weyburn Operations Profile (PDF: 391k).

The unit has undergone extensive development, notably waterflooding and multi-leg horizontal well drilling.

Take a tour of EnCana's Weyburn CO2 Storage.   Low resolution (WMV: 21.3M/14:17 min)   High resolution (WMV: 52.9M/14:17 min)

Learn about CO₂ Miscible flood/sequestration.
Learn about the Enhancing Oil Recovery project (PDF: 282k).

The Weyburn unit was placed on waterflood injection in 1964. This procedure is used to enhance oil recovery by increasing reservoir pressure, which "pushes" oil to producing wells. The unit later began multi-leg horizontal well drilling in 1991. In a horizontal well, the drilling route of the well is altered so that by the time the drilling reaches the oil reservoir, the path is horizontal, not vertical. Continued drilling results in the oil well penetrating much more of the oil reservoir than would have been penetrated vertically; meaning more of the reservoir can be drained. Multi-leg horizontal well drilling occurs when more than one horizontal leg in the oil reservoir is drilled at a time. At Weyburn, water injection capacity was increased by approximately 70,000 bbls/d to assist flood performance.

In 2000, the field began operating on CO2 miscible flood. EnCana purchases CO2 from a coal gasification plant in North Dakota and ships it to Weyburn via pipeline. The CO2 flood has been rolled out to approximately 60 per cent of the unit with plans to continue flood expansion as more CO2 becomes available. The implementation of the CO2 flood, along with the continued infill well development program, has resulted in a 65 per cent increase in oil production, meaning approximately 13,250 barrels (gross) since 2000.

CO2 Miscible Flood/Sequestration
Apart from giving new life to an old field, the use of CO₂ as an injection makes EnCana's Weyburn site the world's largest greenhouse gas sequestration project. From 2000 to 2004, the Weyburn project was the site of a world-scale research initiative operated under the auspices of the International Energy Agency, which studies the sequestration of CO₂ in an oil reservoir. The study concluded that Weyburn is a suitable reservoir for long-term storage of CO₂.

Under the right temperature, pressure and oil composition conditions, CO₂ can act as a solvent, cleaning oil trapped in the microscopic pores of the reservoir rock. This miscible process greatly increases the recovery of oil from a reservoir compared to the recoveries normally seen by waterflooding. The Weyburn unit is an ideal candidate for CO₂ flooding due to the following reasons:

• the waterflood has been very successful and provides confidence that the geology of the reservoir is likely suitable for CO₂ flooding;
• the Weyburn oil swells with the addition of CO₂ and has a large viscosity reduction factor;
• reduced spacing created by the existence of horizontal wells will make the CO₂ process very efficient; and 
• the reservoir pressure required for miscibility can be readily achieved at the reservoir temperature and with Weyburn oil.

Read about the IEA GHG Weyburn-Midale CO2 Monitoring and Storage Project (PDF: 1.1M)

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