Why carbon storage in Alberta?

1. CO2 injection induced chemical composition and mechanical property change of shaly caprock Ming Liu(ming6@ualberta.ca), R. J. Chalaturnyk Department of Civil & Environmental Engineering, University of Alberta, Canada Why carbon storage in Alberta? Methodology Surface chemistry analysis results SEM imaging results • High greenhouse gas emission level • Carbon dioxide ranks No.1 • High storage potential • Chemical Composition • X-ray Photoelectron Spectroscopy (XPS) was introduced to investigate the element change in the surface introduced by exposing to CO2 – rich brine. • Sample image using Scanning Electron Microscope (SEM) coupled with Energy-dispersive X-ray Spectroscopy (EDS). • Mechanical Property • Measurements of capillary entry pressures to study the impact of rock/brine/CO2 interaction. Intact 2 Day 1 Week Figure 1 Alberta annual greenhouse emission and gas type 2 Weeks 3 Weeks > 1 Month Rock/brine/CO2 interactions Figure 4 Overall SEM images of all the testing samples Table 1 Average atom concentrations from XPS (Unit : %) Chemistry analysis conclusions Sampling and Test Condition • Slight decrease in potassium and moderate decrease in aluminum indicate rock/brine/CO2 interactions have indeed resulted in caprock mineralogy change. • Significantly increase in carbon within the shale specimens providing some evidence for the potential of CO2 sorption in this shale that could increase the capacity of storage site. • Further investigations were need for longer reaction time. In order to prevent collapse of shale sample, special holder was used to protect the sample. 1 and 3 Weeks (sphere) 2 Weeks (a) (sphere and chain) 2 Weeks (b) (mixture of two) Figure 5 High resolution images of three types of clusters SEM imaging conclusions Figure 2 Conceptual diagram of a CO2 injection scheme and identified cluster of CO2/rock interactions (Gaus, 2009) • Rock/brine/CO2 interactions result in growth of clusters that disappear over time • There are three kinds of clusters : spherical, chain and mixture of two • Spherical cluster appear to be hollow (CO2trapping) Figure 3 Dimensions and photo of holder – rock system CO2 injectivity Caprock/brine/CO2 interaction • The test conditions are: • P = 2 MPa • T = 50⁰C • The brine composition is 3g/L NaCl Mechanical property change Change in Caprock chemistry