Weyburn-Midale CO2 Project

Facts:

In October 2000, EnCana began injecting significant amounts of CO2 into Cenovus' Weyburn field and Apache’s Midale field, located in southeast Saskatchewan in order to boost oil production. EnCana is operator of the oilfield and holds the largest share of the 37 current partners. The location of the project is the Weyburn oilfield (Canada), first discovered in 1954. It covers and area of some 52,000 acres and has a current oil production rate of ~3,067 m3/day. This comes from a total of 963 active wells made up of 534 vertical wells, 138 horizontal wells, and 171 injection systems. There are also 146 abandoned wells. Current production consists primarily of medium-gravity crude oil with a low gas-to-oil ratio.

Initial CO2 injection rates amounted to ~5,000 ton or 95 million scf/day (2.7 million m3/d). The gas is being supplied via a 205 mile long pipeline (costing 100 million $) from the lignite-fired Dakota Gasification Company synfuels plant site in North Dakota. Overall, it is anticipated that some 20 Mt of CO2 will be permanently sequestered over the lifespan of the project. 

The gas in the pipeline is at very high pressure (about 152 bars), which makes it a supercritical fluid. Supercritical fluids are gases under such high pressures that the vapor (gas) phase becomes as dense as the liquid phase. Supercritical fluids have high density but flow easily like gases, and so are ideal for transporting through pipelines. The Weyburn oil field has a total of 720 wells. The vertical wells were drilled in a “9-spot” grid pattern—eight producing wells in a square around an injection well—and typically have a spacing of around 150 m (500 ft). The high-pressure CO2 is being pumped into 37 injection wells, helping oil to flow toward 145 active producer wells.

When CO2 supercritical fluid is pumped at high pressure into the reservoir, the CO2 mixes with the oil, causing it to swell and become less viscous. The swelling forces oil out of the pores in the rocks, so that it can flow more easily. Water is pumped into the injection wells, alternating with CO2, to push the released oil toward producer wells. Some CO2 comes back out of the ground at producer wells. This is recycled, compressed, and reinjected along with gas from the pipeline.

During its life, the Weyburn project is expected to produce at least 122 million barrels of incremental oil, through miscible or near-miscible displacement with CO2, from a field that has produced 335 million barrels since its discovery in 1955. This will extend the life of the Weyburn field by approximately 20-25 years. It is estimated that ultimate oil recovery will increase to 34%. 

Weyburn CO2 Monitoring Project

Launched in 2000, this 8-year $80 million international project studies CO2 injection and storage underground in depleted oil fields. First Phase (2000 – 2004) to deliver the framework necessary to encourage implementation of CO2 geological storage on a worldwide basis. The monitoring project is unique as researchers have been able to collect background information prior to the flooding of the field with CO2. This allowed comparison of field characteristics before and after CO2 injection and enhancing understanding of interactions and relationships between oil recovery and CO2 storage. 

This IEA activity brings together the interests of 16 countries and the Commission of European Communities. As well, BP Amoco, DMT-FP, EPRI (Electric Power Research Institute, California), Mobil Oil, RWE AG and Shell International are sponsors.

This First Phase consisted of four main themes:

1. Geological characterisation of the geosphere and biosphere

2. Prediction, monitoring and verification of CO2 movements

3. CO2 storage capacity & distribution predictions and the application of economic limits

4. Long term risk assessment of the storage site 

The key elements addressed in the aforementioned themes were: 

• Field-production and analytical data 

• Comprehensive geological modelling, 

• Assessment of geochemical impacts on the formation's CO2 storage integrity and capacity 

• Monitoring of the movement of various fluids within the reservoir 

• Fluid and phase behaviour characterisation to establish the mechanisms that govern the distribution and displacement of the CO2-rich fluids 

• Applied science and research for the development of better sequestration monitoring tools and techniques. 

Collection of baseline research began in September 2000, ahead of CO2 injection, which began in October 2000. Data was collected, analysed and interpreted by the research team. Final results were made available in early 2004.

Findings

• The natural geological setting seems to be highly suitable for the long-term storage of CO2

• The results achieved form the most complete, comprehensive, peer-reviewed data set in the world

• Additional research will however be needed to provide a more comprehensive conclusion.

More information from the IEA GHG R&D database: http://www.co2captureandstorage.info/project_specific.php?project_id=96

The project’s Final Phase is from 2005-2011.

The end deliverable of the Weyburn II CO2 Storage Project/final phase of the Weyburn-Midale CO2 Project will be a Best Practices Manual. This will include technical components (including site characterisation, monitoring and verification, wellbore integrity and performance assessment), and policy components (including regulatory issues, public communication and outreach, and business environment).

More information from the IEA GHG R&D database: http://www.co2captureandstorage.info/project_specific.php?project_id=97

More information and Press Release 

Schlumberger Weyburn Case Study
Canadian Geographic Weyburn Study 
Press release of sucessful CO2 sequester (Nov 2005) 
DOE press release of Successful EOR at Weyburn (Nov 2005) 
EOR adds 25 years to Weyburn oil field (Sep 2001)

Presentation of the project: - The Weyburn CO2 Monitoring and Storage Project (PDF)