Rearranged hopanes in sediments and petroleum

Moldowan, J. Michael; Fago, Frederick J.; Carlson, Robert M. K.; Young, Douglas L.; Duvne, Greg an; Clardy, Jon; Schoell, Martin; Pillinger, C. T.; Watt, David S.

doi:10.1016/0016-7037(91)90492-n

Cited by 289 publications

(102 citation statements)

References 31 publications

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“…The ratio C30Dia/( C30Dia+H) compares the greater thermal stability of diahopane against hopane and is useful for determining oils in the late oil window level of thermal maturity. This marker also follows the same trend as the other markers, increasing in abundance with increasing thermal maturity (Cornford et al, 1988;Moldowan et al, 1991) with an equilibrium cut-off of 0.45.…”

Section: Thermal Maturity Markerssupporting

confidence: 55%

Integrating comprehensive two-dimensional gas chromatography and downhole fluid analysis to validate a spill-fill sequence of reservoirs with variations of biodegradation, water washing and thermal maturity

Forsythe

Martin

Santo

et al. 2017

Fuel

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Optimization of crude oil production depends heavily on crude oil composition and its variation within individual reservoirs and across multiple reservoirs. In particular, asphaltene content has an enormous impact on crude oil viscosity and even the economic value of the fluids in the reservoir. Thus, it is highly desirable to understand the primary controls on crude oil composition and asphaltene distributions in reservoirs. Here, a complex oilfield in the North Sea containing six separate reservoirs is addressed. The crude oil is believed to have spilled out of deeper reservoirs into shallower reservoirs during the overall reservoir charging process. Asphaltene content is measured in-situ through downhole fluid analysis and is generally consistent with a spill-fill sequence in reservoir charging. Detailed compositional analysis of crude oil samples by comprehensive two-dimensional gas chromatography (GC×GC) is used to determine the extent and variation among the reservoirs of water washing, biodegradation and thermal maturity. Increased biodegradation and water washing in the shallower reservoirs is consistent with a spillfill sequence. The water washing is evidently assisted by biodegradation. Moreover, analyses of four thermal maturity biomarkers show that shallower reservoirs contain less mature oil, again consistent with a spill-fill sequence. The combination of DFA for bulk compositional analysis and GC×GC for detailed compositional analysis with geochemical interpretation is an effective tool for unraveling complex oilfield scenarios.

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Section: Thermal Maturity Markerssupporting

confidence: 55%

Integrating comprehensive two-dimensional gas chromatography and downhole fluid analysis to validate a spill-fill sequence of reservoirs with variations of biodegradation, water washing and thermal maturity

Forsythe

Martin

Santo

et al. 2017

Fuel

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“…The bitumen concretions found in both the black shales and green cherts of unit 3 of Xiamaling Formation have similar morphological structure and chemical compositions (Figures 1 and 4, Tables 1 and 2), suggesting similar formation pathways and timing, since the biomarkers of the bitumen and surrounding black shales are so similar, with almost the same hopanes and diahopanes series, such as C 18 ∼C 24 tricyclic terpanes, C 24 tetracyclic terpane (C 24TT ), 18 (H)-17 -methyl-22,29,30-trisnorhopane (Ts), 7 (H)-22,29,30-trisnorhopane (Tm), C 29 ∼C 34 hopanes, and the C 19 ∼C 22 long chain alkyl tricyclic terpanes ( * C 19 ∼ * C 22 ), C 29 preeluting [39], and the diahopanes of * C 29 , C 29 Ts, and * C 30 , suggesting the bitumen should be originated locally from the black shales.…”

Section: The Age Of Bacteria In the Concretions And The Microbialmentioning

confidence: 99%

Remarkable Preservation of Microfossils and Biofilms in Mesoproterozoic Silicified Bitumen Concretions from Northern China

et al. 2017

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Prokaryotes, often generally referred to as "bacteria," are the original and thus oldest life on Earth. They have shaped the chemical environment of the Earth, but they are difficult to find as ancient fossils due to their subtle structure. Here we report well-preserved fossilized microbial communities in silicified bitumen concretions from unit 3 of the Xiamaling Formation (1.39 Ga) in northern China. The numerous silicified bitumen concretions are in a variety of forms including ellipsoidal, spindle, and pancake ones, with diameters of 1∼16 cm and thicknesses of 0.5∼3 cm. The principal planes of the concretions are at low angle or directly parallel to the depositional plane level, showing obvious depositional characteristics. The concretions are silicified with abundant bitumen inside. Many different kinds of microbial fossils are found in the bitumen, including spherical forms, rods, and filaments, and some of the microbes are aggregated together in the forms of multicellular structures. These concretions preserve a delicate Mesoproterozoic biotic community.

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“…Similarly, in the study by Murray et al (1998), the extracts of source rocks from three samples (No.2, 4 and 6) contain moderate to high amounts of C 30 diahopane, while the hydropyrolysis oils for these samples lack or contain negligible amounts of this compound. Moldowan et al (1991) and Peters et al (2005) suggested that C 30 diahopane originates from bacteria in clay-rich sediments deposited under oxic or suboxic conditions. The results of the present and previous studies further demonstrate that this compound is unlikely to originate from the bound hopanoid precursors, but likely comes from the free precursors.…”

Section: Origin Of C 30 Diahopanementioning

confidence: 99%

Organic geochemistry of marine source rocks and pyrobitumen-containing reservoir rocks of the Sichuan Basin and neighbouring areas, SW China

Jiang

Pan

et al. 2014

Marine and Petroleum Geology

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Rearranged hopanes in sediments and petroleum

Cited by 289 publications

References 31 publications

Integrating comprehensive two-dimensional gas chromatography and downhole fluid analysis to validate a spill-fill sequence of reservoirs with variations of biodegradation, water washing and thermal maturity

Integrating comprehensive two-dimensional gas chromatography and downhole fluid analysis to validate a spill-fill sequence of reservoirs with variations of biodegradation, water washing and thermal maturity

Remarkable Preservation of Microfossils and Biofilms in Mesoproterozoic Silicified Bitumen Concretions from Northern China

Organic geochemistry of marine source rocks and pyrobitumen-containing reservoir rocks of the Sichuan Basin and neighbouring areas, SW China

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