Ph.D. Thesis Defense Announcement

CLAY-DOMINANT GEOMATERIALS: FROM SUSPENSIONS TO SHALES

- IMPLICATIONS TO LONG-TERM GAS STORAGE -

By Mengwei Liu

Advisor: Dr. J. Carlos Santamarina (CEE)

Committee Members:  Dr. J. David Frost (CEE), Dr. Susan E. Burns (CEE),

Dr. Angel Palomino (UTK), Dr. Anne-Catherine Dieudonne (TU Delft)

Date and Time:  June 10, 2024.  10 AM EST

Location: Mason 2119 │Virtual link: https://gatech.zoom.us/j/93952033468

Clays are the submicron-to-micron sized phyllosilicate minerals commonly found in
the form of fine-grained sediments and rocks. This thesis investigates claydominant
geomaterials at two extreme conditions: genesis at near-zero effective
stress (fabric formation from clay suspensions and early sediment evolution), and
high effective stress (sealing properties and discontinuities). During genesis,
multiple concurrent processes determine the stability of clay suspensions in
otherwise quiescent stratified water bodies. Geophysical monitoring minimizes
disturbance; the interlayer transition zone acts as a high-pass filter that
preferentially reflects low-frequency long-wavelength P-waves. Multi-scale and
multi-physics experiments and complementary analyses elucidate underlying
processes, such as: aggregation, diffusiophoresis, constrained ion diffusion, graindisplacive
bubble formation, capillary jamming, osmotic swelling, and double-layer
effects. At high effective stress, shales exhibit a complex pore topology defined by the coexistence of clay tactoids, silicates, carbonates, and mature organic matter.
The Hagen-Poiseuille model combines with a fractal pore structure to predict the
evolution of hydraulic conductivity with burial. Discontinuities in tectonically
disturbed shale layers hinder their seal capacity; we advance and test an innovative
sealing solution based on precipitation reactions, where solutions include ethanol
to drive the migration of injected fluids towards the discontinuities in the caprock.
Experimental results and complementary numerical simulations show the evolution
of sealing through multiple injection sequences. Together, these investigations
provide a new understanding of clay-dominant geomaterials, from the atomic scale
to field-scale environmental and energy systems.