Use of noble gas and hydrocarbon geochemistry to determine the source of hydrocarbons in Gulf of Mexico gas hydrates

Thumbnail Image



Journal Title

Journal ISSN

Volume Title


The Ohio State University

Research Projects

Organizational Units

Journal Issue


Global gas hydrate deposits along continental slopes and below permafrost are estimated to contain between 1,000 and 22,000 gigatonnes of carbon. However, their role in the energy sector and the global carbon cycle remains uncertain. Integration of noble gas geochemistry with conventional hydrocarbon molecular and isotopic composition approaches offers an insight into how natural gas contained in hydrates was generated (e.g., biogenic, thermogenic, mixed) and/or the manner in which hydrocarbons contained in clathrates migrated. By integrating the above techniques, one can also help to improve exploration techniques for natural gas in clathrates and help better estimate their economic hydrocarbon extraction potential. Furthermore, the accumulation of 4He can be used to estimate the residence time of fluids associated with clathrate formation in gas hydrate reservoirs. Because the original noble gas composition of a fluid is preserved independent of microbial activity, chemical reactions, or changes in oxygen fugacity, the integration of noble gas data can provide both a geochemical fingerprint for the sources of fluids and an additional insight as to the uncertainty between effects of mixing versus post-genetic modification. Fluids from pressurized cores acquired from the UT-GOM2-01 drilling project in the GC955 block of the Green Canyon within the Gulf of Mexico were analyzed for hydrocarbon molecular composition (e.g., C1-C6), major gas abundances (e.g., H2, N2, CO2), and noble gas elemental and isotopic abundances (e.g., He, Ne, Ar). Clathrates acquired during this cruise were dominantly biogenic in origin and contained evidence of 2-phase migration with a range of residence times of 37,300 years to 575,000 years. The data collected in this study were compared with previously published data from 3 additional locations within the Gulf of Mexico. The additional data displayed gases from regions in the Gulf of Mexico that exhibited a purely biogenic endmember and a region that exhibited a mixture of biogenic and thermogenic sources.



gas hydrates, geochemistry, noble gas, Gulf of Mexico, hydrocarbons