Biodegradation of Hopanes, Steranes and Tricyclic Terpanes in Heavy Oils

Investigation on the biodegradation levels of super heavy oils by parameter-striping method and refined Manco scale: a case study from the Chepaizi Uplift of Junggar Basin

Petroleum Science ◽

10.1007/s12182-020-00542-x ◽

2021 ◽

Author(s):

Xiang-Chun Chang ◽

Bing-Bing Shi ◽

Zhong-Quan Liu ◽

Yue Wang ◽

You-De Xu

Keyword(s):

Refractory Compound ◽

Junggar Basin ◽

Heavy Oils ◽

Volcanic Reservoir ◽

Stripping Method ◽

Magnitude Variation ◽

Absolute Concentrations ◽

Oil Density ◽

Tricyclic Terpanes

AbstractThe Carboniferous volcanic reservoir in the Chepaizi Uplift became an exploration hot target in recent years for its substantial amount of oils discovered. However, most of the Carboniferous heavy oils were biodegraded to PM7 or higher with orders of magnitude variation in oil viscosities. Two oil groups (I and II) exactly corresponding to the western and eastern Chepaizi Uplift were distinguished according to their source diagnose. Furthermore, three oil families (II1, II2 and II3), with the biodegradation level of PM7, PM8–8+, PM9+, respectively, were classified based on molecular compositions and parameter-stripping method of strongly bioresistant parameters. Allowing for this extremely high biodegradation case, more biodegradation refractory compound class were added to establish a refined Manco scale to quantitatively evaluate the biodegradation extent. Refined Manco number (RMN2) positively correlated with the oil density, NSO contents, and absolute concentrations of diasteranes and gammacerane, negatively correlated with the absolute concentrations of diahopane, summed tricyclic terpanes and pentacyclic terpanes. This refined scale showed higher resolution than the PM one to differentiate the biodegradation extent of Carboniferous heavy oils from the Chepaizi Uplift, especially those with same PM values but different oil viscosities.

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Stereoselective biodegradation of tricyclic terpanes in heavy oils from the Bolivar Coastal Fields, Venezuela

Organic Geochemistry ◽

10.1016/s0146-6380(00)00130-3 ◽

2001 ◽

Vol 32 (1) ◽

pp. 181-191 ◽

Cited By ~ 45

Author(s):

M. Alberdi ◽

J.M. Moldowan ◽

K.E. Peters ◽

J.E. Dahl

Keyword(s):

Heavy Oils ◽

Tricyclic Terpanes

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Microscopic versus process parameters in heavy-oil upgrading

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012223x ◽

1992 ◽

Vol 50 (1) ◽

pp. 366-367

Author(s):

V.A. Munoz ◽

R.J. Mikula ◽

C. Payette ◽

W.W. Lam

Keyword(s):

Molecular Weight ◽

Liquid Fuels ◽

Chemical Components ◽

Heavy Oils ◽

Synthetic Fuels ◽

High Hydrogen ◽

Optical Texture ◽

Polar Groups ◽

Anisotropic Character ◽

Planar Molecules

The transformation of high molecular weight components present in heavy oils into useable liquid fuels requires their decomposition by means of a variety of processes. The low molecular weight species produced recombine under controlled conditions to generate synthetic fuels. However, an important fraction undergo further recombination into higher molecular weight components, leading to the formation of coke. The optical texture of the coke can be related to its originating components. Those with high sulfur and oxygen content tend to produce cokes with small optical texture or fine mosaic, whereas compounds with relatively high hydrogen content are likely to produce large optical texture or domains. In addition, the structure of the parent chemical components, planar or nonplanar, determines the isotropic or anisotropic character of the coke. Planar molecules have a tendency to align in an approximately parallel arrangement to initiate the formation of the nematic mesophase leading to the formation of anisotropic coke. Nonplanar highly alkylated compounds and/or those rich in polar groups form isotropic coke. The aliphatic branches produce steric hindrance to alignment, whereas the polar groups participate in cross-linking reactions.

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