The geochemical reactions resulting from CO2 injection into the Midale Formation, Weyburn Oilfield : a laboratory experimental and modelling study

The international IEA Weyburn CO2 Monitoring and Storage Project aims to monitor and predict the behaviour of injected CO2 into the Midale reservoir at the Weyburn oil field in southern Saskatchewan, Canada. One aspect of this project has been to identify likely geochemical changes that result from the injection of CO2 into the reservoir (MidaleFormation). This paper provides a summary of fluid chemical and mineralogical changes occurring in a series of well-constrained laboratory experiments that have utilised samples of Midale core from the Weyburn field and synthetic formation water based upon measured well fluid compositions. This information and other physical data (Durocher et al., this issue) are then used to test, constrain, and verify predictions from geochemical modelling activities, as a prelude to extending theoretical predictions to reservoir-scales and long timescales.