Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.740873
Title: Controls on the distribution of gas hydrates in sedimentary basins
Author: Paganoni, Matteo
ISNI:       0000 0004 7229 5610
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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Abstract:
Natural gas hydrates store a substantial portion of the Earth's organic carbon, although their occurrence is restricted by thermobaric boundaries and the availability of methane-rich fluids. The complexity of geological systems and the multiphase flow processes promoting hydrate formation can result in a mismatch between the predicted and the observed hydrate distribution. The purpose of this research is to achieve a better comprehension of the factors that influence the distribution of gas hydrates and the mechanism of fluid movements beneath and across the gas hydrate stability zone (GHSZ). Therefore, this study integrates seismic, petrophysical and geochemical data from different gas hydrate provinces. This work provides evidence that hydrates can occur below bottom-simulating reflectors, in the presence of sourcing thermogenic hydrocarbons. The relationship between fluid-escape pipes and gas hydrates is further explored, and pipe-like features are suggested to host a significant volume of hydrates. The host lithology also represents a critical factor influencing hydrate and free gas distribution and, in evaluating a natural gas hydrate system, needs to be considered in conjunction with the spatial variability in the methane supply. The three-dimensional distribution of gas hydrate deposits in coarse-grained sediments, representing the current target for hydrate exploration, is shown to be correlated with that of the underlying free gas zone, reflecting sourcing mechanisms dominated by a long-range advection. In such systems, the free gas invasion into the GHSZ appears controlled by the competition between overpressure and sealing capacity of the gas hydrate-bearing sediments. Globally, the thickness of the free gas zones is regulated by the methane supply and by different multi-phase flow processes, including fracturing, capillary invasion and possibly diffusion. In conclusion, this research indicates that geological, fluid flow and stability factors interweave at multiple scales in natural gas hydrate systems.
Supervisor: Foschi, Martino ; Cartwright, Joe A. ; Shipp, Craig R. ; Van Rensbergen, Pieter Sponsor: Royal Dutch Shell plc
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.740873  DOI: Not available
Keywords: Natural gas--Hydrates ; petrophysics ; sedimentary basins ; Fluid flow ; gas hydrates ; seismic interpretation
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