What is the Weyburn-Midale Project (WMP)?

The IEA Greenhouse Gas Programme Weyburn-Midale CO2 Monitoring and Storage Project (WMP for short) was among the world's first studies to examine injection of carbon dioxide (CO2) into geologic reservoirs. CO2 is a greenhouse gas considered to be a major contributor in causing changes to climate patterns. Its storage underground is drawing interest because it provides an option to prevent this gas from reaching the atmosphere. To be successful in this effort, a storage site would have to safely contain the CO2 for a very long time – thousands or even tens of thousands of years.

Between 2000 and 2012 – the years that research was conducted as part of the WMP – some 22 million tonnes of CO2 were injected 1.5 km deep into the Weyburn and Midale oilfields in southeastern Saskatchewan, Canada. The reason that CO2 is being injected into these older, or mature, fields is to increase the amount of oil that can be removed (this process is called enhanced oil recovery or EOR). Without EOR, oil production from these fields would be declining below the cost of production, but as a direct result of CO2 injection, production of oil from each of the reservoirs has increased by three times the levels experienced before injection began. Today, CO2 is still being injected at over 2.5 million tonnes per year and will likely continue for several more decades. See Figure 1 for a summary of the amount of CO2 stored deep underground in the two oilfields by the end of the research project in 2012, as well as daily injection totals.

Although EOR is the main reason for injecting CO2 into the oilfields, the WMP was not focused on the additional oil produced, nor the day-to-day operations of the CO2 capture facility and the CO2 pipeline, nor the CO2 injection. The WMP focused on understanding what happened to the CO2 once it was injected.

The WMP addressed three main questions: 1) where does CO2 go once injected; 2) how does CO2 interact deep underground with the subsurface environment; and 3) will it be securely stored? To answer these questions various measuring and monitoring methods were used.

Figure 1. Total storage of CO2 in both the Weyburn and Midale oilfields as of 2012 are included here (metric tonnes), along with the amounts of CO2 that are injected each day into each field (both that newly arrived from Dakota Gasification Company, and that produced with oil and then reinjected). The total amount stored in both oilfields (22 million tonnes or MT) is the same amount that about 4 million cars emit each year. (Original picture courtesy of the PTRC)

The WMP research focused on seven key areas related to CO2 storage:

  • Understanding the storage site characteristics: Involves looking at the overall geological setting of the storage site to determine its suitability to safely and permanently store CO2. This includes focusing on the reservoir, but also examining the rocks surrounding the storage layer. In the case of Weyburn, over 50,000 cubic kilometers of layers beneath the ground were mapped.
  • Predicting the storage performance: A number of factors impact how much CO2 can be injected and held within a given reservoir. This work investigated the storage potential at the Weyburn oilfield assuming several scenarios that include physical aspects of the rock, but also economic and policy considerations.
  • Measuring and tracking stored CO2: Ways of detecting and measuring changes in rocks and fluids resulting from injection of CO2 (or any fluid) are part of monitoring surveys. The resulting data generally shows us how and where the carbon dioxide is moving in the subsurface. Monitoring can be done in the deep layer of rock in which the carbon dioxide is being injected and also in higher or shallower geological levels, including at surface, or even using satellites.
  • Modeling to confirm the research: Advanced computer modeling can simulate the effects of injecting carbon dioxide to predict future distribution or reservoir performance. One way of checking the models' accuracy is to use them to predict past behaviour in what is known as history matching.
  • Wellbore integrity: Old wells may provide potential leakage routes out of the reservoir. The WMP had a unique testing program conducted within an old well to examine its condition so a realistic assessment could be made of the likelihood of leakage.
  • Risk assessment: Some research helped identify, evaluate, and rank potential risks posed by long-term geologic storage of CO2. Risks considered included those to human health and safety, the environment, changing economic conditions and future operations. Weyburn has a low technical, or geological, risk for leakage.
  • Communicating results and complying with regulations: An extensive outreach program was developed to help inform the general public and governments about the scientific research being undertaken, and to involve people in this ground-breaking research.