Large-Scale Geological Carbon Sequestration - Introduction to Carbon Capture and Sequestration - page 481

C i C g C h C s

C = ϕ • C i • C g • C h • C s

(a)
Multiphase
Flow effects

(b)
Gravity effects

(c)
Heterogeneous
effects

(d)
Structure
effects

Figure 10.3.2 Factors that control the fi lling of pore space
Illustration of various effects that control the fi lling of pore space during the process of
CO 2 injection, where φ is the porosity, and the various capacity factor subscripts are in
the fi gure ( i = multiphase, g = gravity, h = heterogeneity, and s = structural). Adapted
from Doughty et al. [10.30].

these four other effects. The reserve capacity as defi ned using this con-
ceptual framework would be a small fraction of the total resource capac-
ity that might be represented approximately by the porosity multiplied by
the formation volume.

Capacity assessment

Different agencies and groups have developed approaches for estimat-
ing CO 2 storage capacity. Here we compare the different approaches
used by the US Department of Energy (e.g., [10.31]), the Carbon
Sequestration Leadership Forum (CSLF), and the United States Geological
Survey (USGS). Table 10.3.1 gives an overview of these three approaches.
All three approaches require information about the areal extent of the
subsurface formation and the depth, thickness, porosity, and structure(s)
present (e.g., anticlines, synclines, fault traps). The DOE and CSLF
approaches combine all of the complex processes (e.g., those discussed
in Figure 10.3.2 ) into an overall effi ciency factor, E or C c . The difference
between the E and C c effi ciency factors is that the E factor includes the
effect of residual saturation whereas C c does not; the CSLF approach