Successful carbon capture, utilization and storage requires an in-depth knowledge of the complexities of the geological and petrophysical properties that constrain CO2 migration in the subsurface environment. Previous investigations suggests a high potential for carbon capture and storage in a portion of the eastern flank of the Illinois Basin. This conclusion is, in part, due to the thick and widespread reservoir and seal-systems. Fine-grained and clay-rich rock units, collectively termed “shales,” generally function as confining layers of oil and gas accumulations because they limit the upward migration of hydrocarbons or other fluids. This investigation evaluates regional- and fine-scale petrophysical properties and the sealing capacity of the Upper Ordovician Maquoketa Group and stratigraphically equivalent units. To accomplish this, we created a lithofacies model based on the wireline response from gamma-ray, density, and neutron porosity logs from multiple wells in the Illinois Basin. This model resulted in the subdivision of the Maquoketa Group into six lithofacies: (1) limestone; (2) muddy limestone; (3) calcitic/dolomitic shale; (4) silty shale; (5) silt; and (6) shale. We used data collected from core samples, drill cuttings, and portable X-ray fluorescence (pXRF) analyses to calibrate and verify this model, which indicates that the stratigraphic interval is dominated by shale, silty shale, and calcitic/dolomitic shale with subordinate amounts of muddy limestone, limestone, and silt. The results of this model are portrayed by a series of net thickness maps that emphasize areas of higher potential for effective CO2 confinement by the rock sequence. Results from mercury injection capillary pressure (MICP) measurements indicate that the shales have capillary entry pressures adequate to inhibit invasion of supercritical CO2. Spatial and stratigraphic distribution revealed by the regional lithofacies model, coupled with petrophysical characterization, are necessary elements in a strategy to identify regions having high seal potential. In addition, the pore-size distribution and capillary pressure of the Maquoketa Group suggest that, should supercritical CO2 migrate upward and percolate into this unit, the CO2 will be securely trapped by means of capillary mechanisms.

1. Evaluating the Maquoketa Group (Ordovician) as a
seal for the geologic sequestration of CO2: A
lithofacies and petrophysical case study in the
Illinois Basin, Midwest USA
Cristian R. Medina1*; John A. Rupp2; Maria Mastalerz1, 3; Richard W. Lahann1; and Patrick McLaughlin1, 3
1Indiana Geological Survey, Indiana University, Bloomington, Indiana
2Indiana University – Department of Earth and Atmospheric Sciences
3Indiana University –School of Public and Environmental Affairs
*crmedina@indiana.edu

2. Presentation Outline
• Project Background
• Methodology
• Results
• Conclusions

3. Project Background
“The Carbon Storage Assurance Facility Enterprise (CarbonSAFE)
Initiative projects focus on development of geologic storage sites for
the storage of 50+ million metric tons (MMT) of carbon dioxide (CO2)
from industrial sources...”
Source: https://www.netl.doe.gov
www.carbonsafe-illinois.org

4. Upper Ordovician Maquoketa Group
• Project Background
• Methodology
• Results
• Conclusions
A mixed carbonate-clastic succession product
of large amounts of fine-grained siliciclastics
sediments were shed from the eastern
highlands during the Taconic Orogeny.

5. Study Area • Project Background
• Methodology
• Results
• Conclusions

6. Methodology
Geophysical logs (GR, NPHI, RHOB)
• Project Background
• Methodology
• Results
• Conclusions
1
2
3
5
4

7. ELAN in ADM Well
Illite (Vol.) Dol. (Vol.)
Silty Shale
Dol. Shale
ELAN
Dol. Shale
• Project Background
• Methodology
• Results
• Conclusions
1. Limestone: High Ca content (pXRF); low GR; low NPHI; high Ca/Mg ratio.
2. Muddy Limestone: High Si content (pXRF); low GR; medium Ca values.
3. Dolomitic/Calcitic Shale: Medium/high GR; medium-high NPHI; low Ca/Mg ratio.
4-5. Silty Shale or Shale: high GR; high Si content (pXRF).

8. Model • Project Background
• Methodology
• Results
• Conclusions
1
2
3
5
4

9. Output at Each Well: Lithofacies Log 1
2
3
5
4

10. SWW NEE
NEE
SWW
• Project Background
• Methodology
• Results
• Conclusions
Source: Gray, 1972

11. Implications for Sealing Efficiency
Assumptions:
1. Hg to CO2 capillary pressure
conversion: factor of 12.4:
2. Hydrostatic pressure gradient:
0.49 (psi/ft) (0.011 (MPa/m))
3. CO2 density:
rco2(kg/m3) = 712.88 + 0.4427 * P(MPa)
4. CO2 column (h):
∆𝑃 = 𝜌 𝑏𝑟𝑖𝑛𝑒 − 𝜌 𝐶𝑂2 𝑔ℎ:
ℎ20(𝑚) =
𝑃20
9.8 ∗12.4∗ 𝜌 𝑏𝑟𝑖𝑛𝑒−𝜌 𝐶𝑂2
CO2 column assuming
20% intrusion

12. White Co., Illinois Pike Co., IndianaGibson Co., Indiana
Lithofacies Bimodal
Limestone
Muddy Limestone
Dolomitic/Calcitic Shale
Silty Shale
Shale
COLOR CODE
?
?
• Project Background
• Methodology
• Results
• Conclusions

13. Lithofacies Bimodal
Limestone
Muddy Limestone
Dolomitic/Calcitic Shale
Silty Shale
Shale
COLOR CODE
5400
5370
• Project Background
• Methodology
• Results
• Conclusion
Well #1: Gibson County, Indiana

14. Well #2: Pike County, Indiana
White and
Gibson
Counties
4320’

15. Well #3: White County, Illinois
6440”
6100
6150
6200
6250
6300
6350
6400
6450
0 500000
Ca
6100
6150
6200
6250
6300
6350
6400
6450
0 20000
S
6220”
?
XRD
Illite
TrentonLs.

16. Sealing Efficiency – CO2 Column
White County, Illinois
Pike County, Indiana Gibson County, Indiana
ℎ20(𝑚) =
𝑃20
9.8 ∗ 12.4 ∗ 𝜌 𝑏𝑟𝑖𝑛𝑒 − 𝜌 𝐶𝑂2

17. Sealing Efficiency – CO2 Column
1-10 MPa in CO2-Brine SystemP20 ranges between 10-100 MPa

18. Conclusions
• The lithofacies model created from GR, NPHI and RHOB logs looks consistent when
compared with
• known stratigraphy
• previous published work
However, some discrepancies between lithofacies model and petrofacies characteristics are
evident and are due to the associated scales (~1 foot resolution for wireline logs versus
centimeter-size samples for MICP, gas adsorption, pXRF, and XRD analyses).
• Mercury Intrusion Capillary Pressure (MICP) results suggest that, if injecting supercritical
CO2 into the underlying units, the Maquoketa Group will serve as an efficient seal when
considering buoyancy-driven upward flow.

19. Acknowledgements
• This project was funded by the US Department of Energy
through the CarbonSAFE-Illinois East Sub-Basin Project.

20. Thank you!
Questions?
crmedina@indiana.edu
Cristian R. Medina