Experimental Studies on the Geomechanical Behavior and Heterogeneity in Laboratory Synthesized Hydrate-bearing Sands

Pandey, Mandeep Raj

Experimental Studies on the Geomechanical Behavior and Heterogeneity in Laboratory Synthesized Hydrate-bearing Sands

dc.contributor.advisor	Priest, Jeffrey Alan
dc.contributor.advisor	Hayley, Jocelyn L.
dc.contributor.author	Pandey, Mandeep Raj
dc.contributor.committeemember	Wan, Richard G
dc.contributor.committeemember	Wong, Ron Chik-Kwong
dc.contributor.committeemember	Bryant, Steven L.
dc.contributor.committeemember	Pinkert, Shmulik
dc.date.accessioned	2023-09-29T14:22:48Z
dc.date.available	2023-09-29T14:22:48Z
dc.date.issued	2023-09-21
dc.description.abstract	Hydrate-bearing sands (HBS) store large volumes of methane gas, and along with their potential to be commercially exploited using current oil and gas production techniques, make them suitable as a future energy resource. When hydrates form in the pore space of a sediment, they significantly increase the strength and stiffness of the host sediment. The enhancement in mechanical properties is influenced by various factors, such as hydrate saturation, in-situ stress conditions, sediment type (fine-grained or coarse grained). Our current understanding of HBS behavior is based on studies of laboratory synthesized hydrate-bearing specimens, however significant variation in reported values exist that has been suggested to arise from differences in hydrate formation methods, test apparatus, test conditions. Results from testing natural HBS samples, obtained from offshore India, suggest that the particle size impacts geomechanical properties. However, laboratory studies on synthesized specimens are typically conducted on sand specimens with narrow particle size distributions (PSD) and exclude larger particles. As such, there is a lack of understanding of what may lead to variations in mechanical properties of HBS. This thesis reports on a comprehensive experimental program conducted on laboratory synthesized hydrate-bearing sands for two different PSDs, whose particle size was chosen to better represent the coarse fraction observed in natural cores. The laboratory study included detailed analyses of the shear modulus evolution during the formation of hydrates in the pore space of sands. The research also explored the effect that the initial water saturation had on the pressure and temperature conditions when hydrate formation was initiated, along with how it impacted the stress-strain response after hydrate formation. The results from the extensive testing highlighted an inherent heterogeneity in geomechanical behavior of HBS specimens formed and subjected to similar conditions. Conceptual models were developed to help visualize the experimental observations and gain better insights into the factors that led to differences in formation characteristics and resulting hydrate morphology that developed within different sands. The results of this study highlight that the variations in the geomechanical behavior of HBS reported in literature may arise due to the heterogenous distribution of hydrate within laboratory synthesized HBS studies, which is also likely to exist in natural hydrate bearing cores. Observations from the testing will help researchers better understand the behavior of HBS over a wide range of sediment types and formation conditions, like under permafrost, or within offshore seabed sediments.
dc.identifier.citation	Pandey, M. R. (2023). Experimental studies on the geomechanical behavior and heterogeneity in laboratory synthesized hydrate-bearing sands (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/117190
dc.language.iso	en
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	Methane gas hydrate
dc.subject	Geomechanical properties
dc.subject	Particle size distribution
dc.subject	Stiffness
dc.subject	Strength
dc.subject	Sands
dc.subject	Heterogeneity
dc.subject	Hydrate distribution
dc.subject.classification	Engineering--Civil
dc.title	Experimental Studies on the Geomechanical Behavior and Heterogeneity in Laboratory Synthesized Hydrate-bearing Sands
dc.type	doctoral thesis
thesis.degree.discipline	Engineering – Civil
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.