Large-Scale Geological Carbon Sequestration - Introduction to Carbon Capture and Sequestration - page 501

Figure 10.5.3 3D sketch of the injection of CO 2
Sleipner project: 3D sketch of the injection of CO 2 through a horizontal well into a forma-
tion above the one from which natural gas with 9% CO 2 is produced. The light blue
pillars and red broad plumes represent the interpretation of how the buoyant CO 2 is
fi lling the formation in response to repeating discontinuous low-permeability shale layers
(broad plumes) within high-permeability sandstone (pillars). Graphic by Statoil .
is occupying the pore space, the resolution in terms of quantifying how
much CO 2 is being stored, and where this storage is occurring, is not all
that high.
An example of higher-resolution seismic monitoring in both space and
time is provided by the Frio CO 2 injection test in the onshore Texas Gulf
Coast region [10.49]. The Frio CO 2 injection test was carried out in two
phases, in 2004 and 2006. Summarizing the test briefl y, 1600 tonnes of
CO 2 were injected over 10 days in 2004 into the Frio Formation at a depth
of about 5,000 feet. In the second phase in 2006, approximately 300
tonnes of CO 2 were injected into a sandstone layer about 400 feet deeper
than the larger injection of the fi rst phase. Seismic sources and receivers
were set up to provide temporal information on CO 2 migration [10.47].
Figure 10.5.5 shows a sketch of the borehole-based seismic sources and
receivers with seismic ray paths, along with a depiction of the sandstone
layers (colored blue and green). Figure 10.5.5 also shows the successful