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dc.contributor.advisorSassen, Roger
dc.creatorOzgul, Ercin
dc.date.accessioned2004-09-30T01:46:50Z
dc.date.available2004-09-30T01:46:50Z
dc.date.created2002-08
dc.date.issued2004-09-30
dc.identifier.urihttp://hdl.handle.net/1969.1/223
dc.description.abstractMixtures of bacterial and thermogenic methane are found both at vents at the seafloor and in reservoirs in the deep subsurface of the Gulf of Mexico continental slope. The C1-C5 gas that most recently charged reservoirs of Jolliet (GC 184), Genesis (GC 160/161) and Petronius (VK 786) fields is estimated to include 17%-28%, 31%-51%, 31%-49% bacterial methane, respectively. Geochemical assessment of the reservoir gas in the fields show that the gas may be the product of thermal cracking of Upper Jurassic crude oil before final migration to the reservoirs. The gas from three different fields is of similar thermal maturity levels. In contrast to oil in reservoirs in the fields, which shows biodegradation effects, the C1-C5 reservoir gas is unaltered by biodegradation. Late gas migration may have occurred at or near present burial depth and flushed the reservoir system of previously biodegraded hydrocarbon gas to include any previous bacterial methane. Molecular and isotopic properties of reservoir gas and oil suggest that bacterial methane mixed with thermogenic hydrocarbon gas before entering the reservoirs. Thus the source of the bacterial methane is logically deeper than the present depth (>~4 km) and temperatures of the reservoirs. High sedimentation rate and low geothermal gradient may offer conditions favorable for generation and preservation of bacterial methane in deep subsurface petroleum system of the Gulf slope. Bacterial methane dispersed across the large drainage areas of the deep subsurface petroleum system may have been swept by migrating fluids at >4 km, and then charged both vents (GC 185, GC 233 and GC 286) at the seafloor and reservoirs in the deep subsurface. The volume of bacterial methane from geologically significant depth in rapidly subsiding basins may be underestimated.en
dc.format.extent1529856 bytesen
dc.format.extent234242 bytesen
dc.format.mediumelectronicen
dc.format.mimetypeapplication/pdf
dc.format.mimetypetext/plain
dc.language.isoen_US
dc.publisherTexas A&M University
dc.subjectnatural gasen
dc.subjectbacterial methaneen
dc.subjectmixing of gasen
dc.subjectvent gasen
dc.subjectcarbon and hydrogen isotopesen
dc.subjectGulf of Mexico continental slopeen
dc.subjectreservoir gasen
dc.titleGeochemical assessment of gaseous hydrocarbons: mixing of bacterial and thermogenic methane in the deep subsurface petroleum system, Gulf of Mexico continental slopeen
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentGeology and Geophysicsen
thesis.degree.disciplineGeologyen
thesis.degree.grantorTexas A&M Universityen
thesis.degree.nameMaster of Scienceen
thesis.degree.levelMastersen
dc.contributor.committeeMemberAhr, Wayne M.
dc.contributor.committeeMemberKennicutt, Mahlon C.
dc.type.genreElectronic Thesisen
dc.type.materialtexten
dc.format.digitalOriginborn digitalen


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