Correlating biodegradation to magnetization in oil bearing sedimentary rocks

Emmerton, Stacey; Muxworthy, Adrian R.; Sephton, Mark A.; Aldana, Milagrosa; Costanzo-Alvarez, V.; Bayona, Germán; Williams, Wyn

doi:10.1016/j.gca.2013.03.008

Cited by 29 publications

(34 citation statements)

References 68 publications

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“…SEM imaging is particularly important for differentiating between-usually-detrital pyrrhotite and authigenic greigite, which have very different morphologies, but similar magnetic behaviour during magnetic hysteresis when a maximum field of only ∼1 T is available (Roberts et al 2014). As the abundance of magnetic minerals was less typically <<0.001 per cent, magnetic extraction was needed before imaging (Emmerton et al 2012;Emmerton et al 2013b). Samples were crushed to an even grain size (∼50 μm), and passed through a Frantz electromagnet magnetic separator three times following the protocol developed by Chang Figure 1.…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

Using magnetic techniques to calibrate hydrocarbon migration in petroleum systems modelling: A Case Study from the Lower Tertiary, UK Central North Sea

Badejo

Muxworthy

Fraser

et al. 2021

Geophysical Journal International

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Summary Magnetic minerals form or alter in the presence of hydrocarbons, making them a potential magnetic proxy for identifying hydrocarbon migration pathways. In this paper we test this idea by magnetically measuring core samples from the Tay Fan in the Western Central Graben in the Central North Sea. In a companion paper, 3D petroleum systems modelling has been carried out to forward model migration pathways within the Tay Fan. Rock magnetic experiments identified a range of magnetite, maghemite, iron sulphides, siderite, goethite and titanohematite, some of which are part of the background signal, and some due to the presence of hydrocarbons. Typical concentrations of the magnetic minerals were ∼10–200 ppm. Importantly, we have identified an increasing presence of authigenic iron sulphides (likely pyrite and greigite) along the identified lateral hydrocarbon migration pathway (east to west). This is likely caused by biodegradation resulting in the precipitation of iron sulphides, however, though less likely, it could alternatively be caused by mature oil generation, which subsequently travelled with the migrating oil to the traps in the west. These observations suggest mineral magnetic techniques could be a rapid alternative method for identifying the severity of biodegradation or oil maturity in core sample, which can then be used to calibrate petroleum systems models.

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Section: Scanning Electron Microscopymentioning

confidence: 99%

Using magnetic techniques to calibrate hydrocarbon migration in petroleum systems modelling: A Case Study from the Lower Tertiary, UK Central North Sea

Badejo

Muxworthy

Fraser

et al. 2021

Geophysical Journal International

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“…Example applications of MS include: (1) determining the magnetic stratigraphy in loess deposits, lake sediments and marine sediments to reconstruct the paleoenvironmental evolution and erosional history (e.g., Zhang et al, 2012), (2) examining variations in the detrital input of magnetic minerals related to climate change (e.g., Da Silva et al, 2013), (3) aiding archeological investigations (Walach et al, 2011), (4) serving as a proxy for extreme hydrologic events and rainfall (Li et al, 2019), ( 5) monitoring soil pollution (Hoffmann et al, 1999;D'Emilio et al, 2007;Zhang et al, 2012), and (6) investigating the movement of tectonic plates. Further, the MS technique has also been used for oil exploration (e.g., Guzmán et al, 2011), for evaluation of oil bearing units (Perez-Perez et al, 2011;Emmerton et al, 2013) and reservoir properties (Potter, 2007;Potter and Ivakhnenko, 2008).…”

Section: Introductionmentioning

confidence: 99%

Methanogens and Their Syntrophic Partners Dominate Zones of Enhanced Magnetic Susceptibility at a Petroleum Contaminated Site

et al. 2021

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Geophysical investigations documenting enhanced magnetic susceptibility (MS) within the water table fluctuation zone at hydrocarbon contaminated sites suggest that MS can be used as a proxy for investigating microbial mediated iron reduction during intrinsic bioremediation. Here, we investigated the microbial community composition over a 5-year period at a hydrocarbon-contaminated site that exhibited transient elevated MS responses. Our objective was to determine the key microbial populations in zones of elevated MS. We retrieved sediment cores from the petroleum-contaminated site near Bemidji, MN, United States, and performed MS measurements on these cores. We also characterized the microbial community composition by high-throughput 16S rRNA gene amplicon sequencing from samples collected along the complete core length. Our spatial and temporal analysis revealed that the microbial community composition was generally stable throughout the period of investigation. In addition, we observed distinct vertical redox zonations extending from the upper vadose zone into the saturated zone. These distinct redox zonations were concomitant with the dominant microbial metabolic processes as follows: (1) the upper vadose zone was dominated by aerobic microbial populations; (2) the lower vadose zone was dominated by methanotrophic populations, iron reducers and iron oxidizers; (3) the smear zone was dominated by iron reducers; and (4) the free product zone was dominated by syntrophic and methanogenic populations. Although the common notion is that high MS values are caused by high magnetite concentrations that can be biotically formed through the activities of iron-reducing bacteria, here we show that the highest magnetic susceptibilities were measured in the free-phase petroleum zone, where a methanogenic community was predominant. This field study may contribute to the emerging knowledge that methanogens can switch their metabolism from methanogenesis to iron reduction with associated magnetite precipitation in hydrocarbon contaminated sediments. Thus, geophysical methods such as MS may help to identify zones where iron cycling/reduction by methanogens is occurring.

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“…Inorganic greigite often occurs as framboidal clusters, so the findings of Muxworthy et al (2013) cannot be applied directly to framboids. Given that natural framboidal structures are found commonly in greigite and magnetite (e.g., Rowan and Roberts, 2006;Emmerton et al, 2013), there is a need to understand their magnetic hysteresis loops and FORC signatures.…”

Section: Introductionmentioning

confidence: 99%

Micromagnetic simulations of first-order reversal curve (FORC) diagrams of framboidal greigite

Valdez-Grijalva

Nagy

Muxworthy

et al. 2020

Geophysical Journal International

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SUMMARY Greigite is a sensitive environmental indicator and occurs commonly in nature as magnetostatically interacting framboids. Until now only the magnetic response of isolated non-interacting greigite particles have been modelled micromagnetically. We present here hysteresis and first-order reversal curve (FORC) simulations for framboidal greigite (Fe3S4), and compare results to those for isolated particles of a similar size. We demonstrate that these magnetostatic interactions alter significantly the framboid FORC response compared to isolated particles, which makes the magnetic response similar to that of much larger (multidomain) grains. We also demonstrate that framboidal signals plot in different regions of a FORC diagram, which facilitates differentiation between framboidal and isolated grain signals. Given that large greigite crystals are rarely observed in microscopy studies of natural samples, we suggest that identification of multidomain-like FORC signals in samples known to contain abundant greigite could be interpreted as evidence for framboidal greigite.

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Correlating biodegradation to magnetization in oil bearing sedimentary rocks

Cited by 29 publications

References 68 publications

Using magnetic techniques to calibrate hydrocarbon migration in petroleum systems modelling: A Case Study from the Lower Tertiary, UK Central North Sea

Using magnetic techniques to calibrate hydrocarbon migration in petroleum systems modelling: A Case Study from the Lower Tertiary, UK Central North Sea

Methanogens and Their Syntrophic Partners Dominate Zones of Enhanced Magnetic Susceptibility at a Petroleum Contaminated Site

Micromagnetic simulations of first-order reversal curve (FORC) diagrams of framboidal greigite

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