CO₂-EOR: Security of Storage

Abstract

Preliminary studies from CO2-EOR in Canada have suggested that, in CO2-EOR settings, solubility trapping takes place within both aqueous and hydrocarbon phases. As such it is postulated that CO2-EOR may provide a greater quantity of securely stored CO2 than a purely non-EOR storage operation. This study's principal objective was to quantify how much solubility trapping takes place within both aqueous and hydrocarbon phases in CO2-EOR settings. The Pembina Cardium CO2 Monitoring Pilot Project was used as a test site to determine the relative roles of solubility trapping. Firstly two geochemical approaches using empirical data from the site (gas geochemistry, production volumes and water isotope geochemistry) were used to determine the phase distribution of CO2 (dissolved or free phase) at a number of production wells that were sampled monthly during a two-year CO2 injection pilot. In addition a simplified reservoir simulation was performed to use it as a test-bed to investigate various CO2 injection scenarios with a model having some of the salient features of the pilot project. In particular this model was used to test the observations of the role of solubility trapping versus free-phase CO2 trapping.