Detection of Microbially Produced Gaseous Hydrocarbons Other than Methane

Davis, John; Squires, Rodney M.

doi:10.1126/science.119.3090.381

Cited by 89 publications

(36 citation statements)

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“…Laboratory studies as well as empirical observations show that traces of the wet gases (ethane and propane) can be produced via biological processes and a number of the organisms responsible have been identified [15,16,62,66,67]. Using the presence of ethane and propane, no matter how low the concentration, as an indicator of thermogenic sourcing is not correct.…”

Section: Significance Of Wet Gasesmentioning

confidence: 99%

Evaluation of Near-Surface Gases in Marine Sediments to Assess Subsurface Petroleum Gas Generation and Entrapment

Abrams

2017

Geosciences

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Gases contained within near-surface marine sediments can be derived from multiple sources: shallow microbial activity, thermal cracking of organic matter and inorganic materials, or magmatic-mantle degassing. Each origin will display a distinctive hydrocarbon and non-hydrocarbon composition as well as compound-specific isotope signature and thus the interpretation of origin should be relatively straightforward. Unfortunately, this is not always the case due to in situ microbial alteration, non-equilibrium phase partitioning, mixing, and fractionation related to the gas extraction method. Sediment gases can reside in the interstitial spaces, bound to mineral or organic surfaces and/or entrapped in carbonate inclusions. The interstitial sediment gases are contained within the sediment pore space, either dissolved in the pore waters (solute) or as free (vapour) gas. The bound gases are believed to be attached to organic and/or mineral surfaces, entrapped in structured water or entrapped in authigenic carbonate inclusions. The purpose of this paper is to provide a review of the gas types found within shallow marine sediments and examine issues related to gas sampling and extraction. In addition, the paper will discuss how to recognise mixing, alteration and fractionation issues to best interpret the seabed geochemical results and determine gas origin to assess subsurface petroleum gas generation and entrapment.

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Section: Significance Of Wet Gasesmentioning

confidence: 99%

Evaluation of Near-Surface Gases in Marine Sediments to Assess Subsurface Petroleum Gas Generation and Entrapment

Abrams

2017

Geosciences

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“…Previous work has also pointed to the existence of microbially mediated pathways that yield hydrocarbons with two or more carbon atoms (6)(7)(8)(9)(10)(11)(12). In the present case, the occurrences of ethane and propane in each core are well correlated with pertinent biogeochemical factors and chances that migration could supply the ethane and propane are profoundly more remote.…”

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confidence: 99%

Biological formation of ethane and propane in the deep marine subsurface

Hinrichs

Hayes²,

Bach

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

230

130

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Concentrations and isotopic compositions of ethane and propane in cold, deeply buried sediments from the southeastern Pacific are best explained by microbial production of these gases in situ. Reduction of acetate to ethane provides one feasible mechanism. Propane is enriched in 13 C relative to ethane. The amount is consistent with derivation of the third C from inorganic carbon dissolved in sedimentary pore waters. At typical sedimentary conditions, the reactions yield free energy sufficient for growth. Relationships with competing processes are governed mainly by the abundance of H2. Production of C2 and C3 hydrocarbons in this way provides a sink for acetate and hydrogen but upsets the general belief that hydrocarbons larger than methane derive only from thermal degradation of fossil organic material.ethanogenesis ͉ hydrocarbon gases ͉ marine sediments ͉ propanogenesis ͉ stable carbon isotopes L eg 201 of the Ocean Drilling Program was dedicated to the study of microbial life in deeply buried marine sediments (1, 2). Cores were obtained from open-ocean sites in the Equatorial Pacific, where sediments deposited 40 million years ago are underlain by seafloor basalts through which oxygenated seawater is flowing, and from the Peruvian Margin, where drilling penetrated sediments up to 15 million years old (Fig. 1). Temperatures in sediments ranged from 2°C to 25°C. All sites are isolated from reservoirs of fossil hydrocarbons. At both openocean and ocean-margin sites, treatment of sediments with strong base released ethane and propane (Fig. 2). When the treatment was repeated with fresh sediment and isotopically labeled water (␦D ϭ ϩ4000‰), no excess deuterium appeared in the ethane or propane. Therefore, we conclude that the hydrocarbons were strongly sorbed, indigenous constituents of the sediment and did not derive from a chemical reaction between the strong base and an organic substrate.Earlier reports describe sediments offshore Peru (3) and Spitsbergen (4), from which similar mixtures of hydrocarbons could be released by treatment with hot solutions of phosphoric acid. In each case, the carbon-isotopic compositions and abundance ratios (C 1 ͞C 2ϩ ) led to reluctant suggestions that the gases must be of thermogenic origin and thus have migrated into the unconsolidated seafloor sediments: ''the [postulated] migration of C 2ϩ hydrocarbons. . . is somehow related to these fluids [brines that might have flowed from one basin to another]'' (3); and ''. . . elevated seepages [of thermogenic hydrocarbons] occurred irregularly but are not currently active. . . it remains speculative whether the detected hydrocarbon anomalies are related to reservoirs and͞or active source rocks'' (4). No mechanism for sorbing the putatively migrated hydrocarbons more strongly than indigenous microbial products has been offered.Ethane and propane with similar isotopic characteristics and abundance ratios have recently been reported in Cretaceous marine shales in the Western Canadian sedimentary basin (5). Previous work has also pointe...

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“…However, this has never been demonstrated in pure culture despite numerous attempts (Stone and Zobell, 1952). If bacterial production of these compounds is occurring, it must happen either only in mixed culture or when the organisms encounter stress, such as a limited food supply; it has been noted sporadically in the literature that C 2 to C 5 hydrocarbons, in the approximate relative concentrations encountered in this hole, are occasionally asso- ciated with anoxic mud and sewage sludge (Davis and Squires, 1954;Bokova, 1959;Malyshek, 1962;Stone and Zobell, 1952;Weber and Maximov, 1976). A second possibility is that the C 2 to C 5 compounds arise from a low temperature chemical process using remains from the bacterial community as source material.…”

Section: Figure 3 Logs Of Ratios Of Iso-butane/n-butane (\C 4 /Nc 4 mentioning

confidence: 99%

C1 to C7 Hydrocarbons from IPOD Holes 397 and 397A

Whelan¹

1979

Initial Reports of the Deep Sea Drilling Project

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Gases from sediment pockets were monitored onboard ship during continuous coring to a depth of 1453 meters. Gas pockets first appeared at a sediment depth of 80 meters (Hole 397) and continued irregularly to the bottom of Hole 397A. The gas contained small quantities (0.1 to 1.3%) of methane from 30 to 124 meters, with major components of air and C0 2 . The odor of H 2 S was noted in the cores from 9 to 151 meters. Starting at 196 meters, methane became a significant component (43%) and then varied irregularly from 1 to 81 per cent of the gas throughout the rest of the hole. A gas chromatograph installed on board ship at the beginning of Leg 47A allowed monitoring of traces of C 2 to C 5 hydrocarbons in gas pockets. These hydrocarbons, found along with the methane throughout the hole, included 3 to 2000 ppm of C 2 by volume, 1 to 140 ppm of C 3 , 0.1 to 25 ppm of C 4 , and 0.1 to 4 ppm of C 5 . The Cj to C 5 hydrocarbon levels followed lithologic changes to a remarkable degree with proportions of C 2 :C 3 :C 4 :C 5 staying relatively constant in fine-grained sediments and with the (Cj + C 2 )/(C 3 + C 4 + C 5 ) ratio increasing erratically in coarser grained sediments and at most of the unconformities. This indicates hydrocarbons were migrating from fine-grained source beds to coarse-grained reservoir beds and along the more permeable unconformities throughout the hole. Ratios of i-C 5 /n-C 5 and i-C 4 /n-C 4 , appeared to vary with changes in organic source material. Traces of neopentane occurred irregularly and are probably indicative of terpene-derived material. Sediment C± to C 7 , analysis showed that only traces of C 6 and C 7 hydrocarbons were present above 800 meters. Below 800 meters, the C 6 and C 7 hydrocarbons generally increased with sediment depth and age.

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Detection of Microbially Produced Gaseous Hydrocarbons Other than Methane

Cited by 89 publications

References 1 publication

Evaluation of Near-Surface Gases in Marine Sediments to Assess Subsurface Petroleum Gas Generation and Entrapment

Evaluation of Near-Surface Gases in Marine Sediments to Assess Subsurface Petroleum Gas Generation and Entrapment

Biological formation of ethane and propane in the deep marine subsurface

C1 to C7 Hydrocarbons from IPOD Holes 397 and 397A

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