Unconventional formations have become an increasingly important source of energy
resources. Proper rock mechanic characterization is needed not only to identify the most
promising areas for stimulation, but to increase our understanding of the sealing capabilities of
cap-rock formations for carbon geological storage. However, shale assessment is challenging
with current standard techniques. This research explores the index and rock mechanic properties
of different shale specimens considered as source rocks for oil and gas (Eagle Ford, Wolfcamp,
Jordanian, Mancos, Bakken, and Kimmeridge), and presents an in-depth analysis of tools and
protocols to identify inherent biases.
New test protocols proposed in this thesis provide robust and cost-effective measurement
techniques to characterize shale formations in general; these include: 1) new energy methods
computed from the area under the stress-strain curve or proposed boundary asymptotes (strength
and stiffness) to assess brittle/ductile conditions in the field, 2) tensile strength analyses to
determine anisotropy in shale formations, 3) Coda wave analysis to monitor pre-failure damage
evolution during compression, and 4) a combination of index tests to anticipate the complicated
geology or layered characteristics, which include high-resolution imaging, hardness, and scratch
tests.
Experimental results combined with extensive databases provide unprecedented information
related to the mechanical behavior of shale formations needed for the enhanced design and
analysis of geo-engineering applications. Calcareous shales display strong interlayer bonding and
lower compressive strength anisotropy than siliceous shales. Tensile strength anisotropy is more
pronounced than in compressive strength and reflects bedding orientation and loading conditions
that affect fracture propagation and ensuing failure surface topography.
| Date of Award | Dec 2020 |
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| Original language | English (US) |
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| Awarding Institution | - Physical Sciences and Engineering
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| Supervisor | J. Carlos Santamarina (Supervisor) |
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