Synchrotron X-ray Micro-Tomography and Geological
CO2 Sequestration
P. S. Nico* — J. B. Ajo-Franklin* — S. M. Benson** — A. McDowell* — D. B.
Silin* — L. Tomutsa* — Y. Wu*
In this study, synchrotron beamline is used to analyse the distribution of CO2 within rock samples flooded with
two phase CO2/brine system. Additionally the authors use time-lapse imaging to characterize microbially driven
precipitation events.
They use multi-energy imaging to distinguish CO2 within a sandstone. Using some image analysis
techniques such as Maximum Inscribed Sphere (MIS), the come up with distribution of CO2 as well as an
effective radius (capillary radius) for the pore. (I don’t see what’s new here?!).
Next, they do time lapse imaging (over a two-week period) by designing a flow-through bioreactor, which
can be scanned continuously during precipitation experiments.
No tangible conclusions. This work is more of a methodology rather than important results.
Residual CO2 Saturation Distributions in Rock Samples
Measured by X-ray CT
H. Okabe* — Y. Tsuchiya* — C. H. Pentland** — S. Iglauer** — M. J. Blunt**
They conducted in-situ coreflood experiments on sandstones and carbonate rocks using scCO2 and brine.
The flooding procedure was as follows: scCO2 was injected into a brine saturated core followed by injection of
CO2 saturated brine and they measured the residual CO2 saturation as a result of capillary trapping.
Results:
- They show that the trapped CO2 saturation ranges from 0.2 to 0.4 for rocks with the permeability ranging
from 6 to 220 md.
- Using in-situ saturation monitoring, they show a piston-like displacement mechanism inside
homogeneous sandstone, while heterogeneous flow behavior is observed on a carbonate rock.
- Injected CO2 flows through more porous regions, while it is trapped in lower porosity zones
X-ray CT Imaging of Coal for Geologic Sequestration of
Carbon Dioxide
D. H. Smith — S. A. Jikich
Abstracts: Concerns about global warming have motivated research and field projects for geologic sequestration of
carbon dioxide by its injection into unmineable coal seams. We report x-ray CT measurements of coal
heterogeneities and high-permeability regions in coal, bulk compressibilities and carbon dioxide concentration
gradients produced by its diffusion through the coal matrix. Gravimetric measurements performed to examine the
accuracy of the CT measurements of carbon dioxide concentrations also are discussed.
Conclusion: In support of the development of geologic sequestration of carbon dioxide in coal, density
heterogeneities of (bituminous) Pittsburgh coal have been measured by x-ray CT imaging. Spatial
distributions of carbon dioxide sorbed within the coal also are reported. The effects of sorption followed by
desorption on changes of coal density are examined. Measurements that illustrate the slow diffusion of
carbon dioxide have been made. To ensure that the measured CO2 concentrations were accurate,
concentrations of sorbed carbon dioxide as measured by x-ray CT were compared with concentrations
measured by a novel gravimetric technique.