Why carbon storage in Alberta?

• High greenhouse gas emission level

• Carbon dioxide ranks No.1

• High storage potential

Figure 1 Alberta annual greenhouse emission and gas type

Rock/brine/CO2 interactions

Methodology

Chemical CompositionX-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 PropertyMeasurements of capillary entry pressures to

study the impact of rock/brine/CO2 interaction.

Surface chemistry analysis results

Figure 2 Conceptual diagram of a CO2 injection scheme and identified cluster of CO2/rock interactions (Gaus, 2009)

CO2 injectivity

Mechanical property change

Caprock/brine/CO2 interaction

Change in Caprock

chemistry

Sampling and Test ConditionIn order to prevent collapse of shale sample,

special holder was used to protect the sample.

Figure 3 Dimensions and photo of holder – rock system

Table 1 Average atom concentrations from XPS (Unit : %)

• 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.

SEM imaging results

Intact

> 1 Month3 Weeks

1 Week2 Day

2 Weeks

Figure 4 Overall SEM images of all the testing samples

• 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)

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

Chemistry analysis conclusions

SEM imaging conclusions

CO2 injection induced chemical composition and mechanical property change of shaly caprock

Ming Liu(ming6@ualberta.ca), R. J. ChalaturnykDepartment of Civil & Environmental Engineering, University of Alberta, Canada

The test conditions are:• P = 2 MPa • T = 50⁰C• The brine composition is 3g/L NaCl