Improved assessment of biodegradation extent and prediction of petroleum quality

Elias, Rouven; Vieth, Andrea; Riva, A.; Horsfield, Brian; Wilkes, Heinz

doi:10.1016/j.orggeochem.2007.07.004

Cited by 35 publications

(15 citation statements)

References 31 publications

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“…The absence of biomarkers such as n-and iso-alkanes, acyclic isoprenoids, phenanthrene, 1-and 2-isomers of methylphenanthrene, and of the four isomers of methyldibenzothiophene in samples TR-12A, TR-12B, -13,-14 and -15 is consistent with severe biodegradation and, to a lesser extent, water washing (e.g. Connan, 1984;Palmer, 1984;Volkman et al, 1984;Watson et al, 2007;Elias et al, 2007;Permanyer et al, 2010;Ross et al, 2010). According to criteria previously established in the literature (Palmer, 1984;Peters et al, 2005), the rest of the oil seeps appear to be moderately biodegraded and waterwashed, considering the significant depletion in acyclic isoprenoids, phenanthrene, 1-and 2-isomers of methylphenanthrene, as well as 2-, 3-, and 4methyldibenzothiophenes.…”

Section: Classification Of the Seepage Oilsmentioning

confidence: 89%

Main Factors Controlling the Compositional Variability of Seepage Oils From Trujillo State, Western Venezuela

Galarraga

Urbani

Escobar

et al. 2010

Journal of Petroleum Geology

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The organic geochemistry of eighteen samples of seepage oils from Trujillo State, Western Venezuela, was investigated. These oils are probably derived from the predominantly marine Cretaceous La Luna Formation which is near peak maturity for oil generation. A range of biomarkers (n‐alkanes, acyclic isoprenoids, phenanthrene and alkyl‐phenanthrenes, as well as dibenzothiophene and alkyl‐dibenzothiophenes) were analysed by gas chromatography ‐ mass spectrometry (GC‐MS). The seepage oils have been modified as a result of water washing and biodegradation. A first group of samples were slightly biodegraded with the partial loss of n‐ and iso‐alkanes. Other samples fall into two groups: those that are moderately degraded, with partial depletion of acyclic isoprenoids; and those that are severely altered, as indicated by the partial or total absence of hopanes. One objective of this work was to evaluate the factors influencing the compositional differences of the three samples sets. In‐situ measurements, together with the interpretation of the geochemical data, suggest that diverse factors were responsible for these variations. These included different degrees of alteration due to biodegradation and water washing, as well as differences in flow rate towards the surface.

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Section: Classification Of the Seepage Oilsmentioning

confidence: 89%

Main Factors Controlling the Compositional Variability of Seepage Oils From Trujillo State, Western Venezuela

Galarraga

Urbani

Escobar

et al. 2010

Journal of Petroleum Geology

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“…Physical and chemical alteration of petroleum under surface or reservoir conditions caused by bacteria is referred to as "biodegradation" Watson et al 2000;Röling et al 2006;Elias et al 2007). Microbial/bacterial deterioration essentially develops starting from bacteria and causes chemical structures and components rich in hydrogen to dissolve.…”

Section: Alteration Degree Of Karadere Oil Seep (Solid Bitumen)mentioning

confidence: 99%

“…Washing with water, usually observed together with biodegradation, has a very little impact on the physical and chemical properties of petroleum by itself, whereas bacterial activity increases deterioration. As a result of the reduction in light components, the remaining product becomes rich in polar and aromatic components, which means a drop in the economic value for the petroleum reservoir Watson et al 2000;Röling et al 2006;Elias et al 2007). Components in different groups such as benzene, toluene, and other aromatics disappear sequentially or simultaneously due to biodegradation (Palmer 1993;Peters et al 1986;Elias et al 2007).…”

Section: Alteration Degree Of Karadere Oil Seep (Solid Bitumen)mentioning

confidence: 99%

“…As a result of the reduction in light components, the remaining product becomes rich in polar and aromatic components, which means a drop in the economic value for the petroleum reservoir Watson et al 2000;Röling et al 2006;Elias et al 2007). Components in different groups such as benzene, toluene, and other aromatics disappear sequentially or simultaneously due to biodegradation (Palmer 1993;Peters et al 1986;Elias et al 2007). The kinetics of biodegradation is associated with the composition of the petroleum and may develop rapidly (e.g., disappearance of n-alkanes) or slowly (e.g., disappearance of resins and asphaltenes).…”

Section: Alteration Degree Of Karadere Oil Seep (Solid Bitumen)mentioning

confidence: 99%

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Hydrocarbon generation potential of late cretaceous shales and carbonates in Hekimhan basin and genetic relationships with Karadere oil seep (Eastern Anatolia Region, Turkey)

Erik

2018

J Petrol Explor Prod Technol

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In this study, Karadere oil seep (solid bitumen) and Late Cretaceous shales and carbonate levels of the Hekimhan Formation in Hekimhan Basin are compared genetically by means of organic-geochemical data. Investigated shale samples have generally low (< 0.5%) the total organic carbon values (TOC, wt%) and there is no petroleum and gas source-rock potential; however, the amount (0.11-5.92%) and type (type II-III kerogen) of organic matter within limestone are consistent for source-rock potential. On the basis of average T max (433 °C) and 0.53% R 0 values, the investigated samples are at the immature and early mature level for hydrocarbon generation. According to biomarker data, the bitumen is pre-Cretaceous in age, highly reducing conditions, formed in a marine depositional environment at normal salinity, and under the influence of high bacterial activity, and was originate from an immature carbonate source rock. These geochemical data are highly in agreement with the late Cretaceous limestone of the Hekimhan Formation, and these rocks may be considered the source rock of the solid bitumen. However, these organic richness zones formed from non-indigenous organic material, and therefore, it is concluded that this seepage which generates from non-indigenous organic materials cannot be due to the limestone at the evaluated level. On the basis of organic-geochemical evaluations, it has been concluded that, in Hekimhan Basin, some hydrocarbons developed in deeper, more mature intervals of the limestone, and that these were migrated probably only a short distance within the basin and became really surfaced in relation to tension fractures.

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“…During biodegradation, various classes of compounds are degraded simultaneously but at significantly different rates (Peters et al, 1996;Elias et al, 2007). Biodegradation kinetics depend on the range of compounds present in an oil, and the resulting processes can be rapid (e.g.…”

Section: Crude Oil Biodegradation and Environmental Factors At The Rimentioning

confidence: 99%

Crude Oil Biodegradation and Environmental Factors at the Riutort Oil Shale Mine, Se Pyrenees

Permanyer

Gallego

Caja

et al. 2010

Journal of Petroleum Geology

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Liquid oil seeps from organic‐rich source rock intervals in the Eocene Armàncies Formation in the walls of the underground Riutort oil‐shale mine in the SE Pyrenees. The mine was excavated at the beginning of the last century for oil shale extraction. For this study, oil samples were recovered from fractures in the mine walls, and from pools of water on the mine floor. Some oil is present at the bottom of these pools; oil also floats on the surface of the water in association with emulsions colonized by microbial mats. The oils have undergone variable degrees of biodegradation. The physical and chemical environment in the mine was studied in order to establish the controls on biodegradation processes. The results show that the degree of biodegradation depended on factors including the location of the oil (i.e. floating on the top of the water or from the bottom of a pool), and the addition of fresh seepage oil. The biodegradation observed mainly involved the progressive removal of n‐alkanes, isoprenoids and some aromatics. Biodegradation was also assessed in terms of the sulphur content and by quantitative analyses of molecular markers in the aromatic fraction. These approaches indicated that at least 50% of the oil was lost as a result of biodegradation. Isotope studies were also undertaken but isotope signatures did not provide significant data. Microbiological data were consistent with data collected from chemical analyses. Evidence for the presence of hydrocarbon‐degrading bacteria were obtained from laboratory studies.

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Improved assessment of biodegradation extent and prediction of petroleum quality

Cited by 35 publications

References 31 publications

Main Factors Controlling the Compositional Variability of Seepage Oils From Trujillo State, Western Venezuela

Main Factors Controlling the Compositional Variability of Seepage Oils From Trujillo State, Western Venezuela

Hydrocarbon generation potential of late cretaceous shales and carbonates in Hekimhan basin and genetic relationships with Karadere oil seep (Eastern Anatolia Region, Turkey)

Crude Oil Biodegradation and Environmental Factors at the Riutort Oil Shale Mine, Se Pyrenees

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