Return to search

Experimental Study of the PVTX Properties of the System H₂O-CH₄

The system H₂O-CH₄ is found in a variety of geological environments in the earth’s crust, from sedimentary basins to low grade metamorphic terrains. Knowledge of the PressureVolume-Temperature-Composition (PVTX) properties of the H₂O-CH₄ system is necessary to understand the role that these fluids play in different geological environments. In this study the properties of the H₂O-CH₄ fluid system at elevated temperatures and pressures has been investigated experimentally to determine the PVTX properties of H₂O-CH₄ fluids in the P-T range equivalent to late diagenetic to low grade metamorphic environments, and XCH₄≤4mol%. A study has also been conducted to determine methane hydrate stability over the temperature range of -40~20°C. Synthetic fluid inclusions were employed in both studies as miniature autoclaves.

Experimental data for the PVTX properties of H₂O-CH₄ fluids under late diagenetic to low grade metamorphic conditions was used to calculate the slopes of isoTh lines (the line connecting the P-T conditions of the inclusions at formation and at homogenization) at different PTX conditions. An empirical equation to describe the slope of iso-Th line as a function of homogenization temperature and fluid composition was developed. The equation is applicable to natural H₂O-CH₄ fluid inclusions up to 500°C and 3 kilobars, for fluid compositions ≤4 mol% CH₄.

The Raman peak position of CH₄ gas is a function of the pressure and temperature. This relationship was used to determine the pressure along the methane hydrate stability curve in the H₂O-CH₄ system. The combined synthetic fluid inclusion, microthermometry and Raman spectroscopy method is a novel experimental approach to determine the P-T stability conditions of methane hydrates. The method is fast compared to conventional methods, and has the potential to be applied to study other gas hydrate systems. / Ph. D.

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/29205
Date21 October 2005
CreatorsLin, Fang
ContributorsGeosciences, Bodnar, Robert J., Read, James Fredrick, Dove, Patricia M., Sum, Amadeu K., Schreiber, Madeline E.
PublisherVirginia Tech
Source SetsVirginia Tech Theses and Dissertation
Detected LanguageEnglish
TypeDissertation
Formatapplication/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/
RelationFLin_Dissertation.pdf

Page generated in 0.0019 seconds