As a new technology of analyzing crude oils, comprehensive two-dimensional gas chromatography cou- pled with time-of-flight mass spectrometry （GCxGC- TOFMS） has received much research attention. Here we present a ca...As a new technology of analyzing crude oils, comprehensive two-dimensional gas chromatography cou- pled with time-of-flight mass spectrometry （GCxGC- TOFMS） has received much research attention. Here we present a case study in the Junggar Basin of NW China. Results show that the hydrocarbons, including saturates and aromatics, were all well-separated without large co- elution, which cannot be realized by conventional one-dimensional GC-MS. The GC×GC technique is especially effective for analyzing aromatics and low-to-middle- molecular-weight hydrocarbons, such as diamondoids. The geochemical characteristics of crude oils in the study area were investigated through geochemical parameters extracted by GC×GC-TOFMS, improving upon the understanding obtained by GC-MS. Thus, the work here represents a new successful application of GC×GC- TOFMS, showing its broad usefulness in petroleum geochemistry.展开更多
For our ancestors, oil seeps were both a fascination and a resource but as the planet's reserves of high quality low density oil becomes increasingly depleted, so there is now a renewed interest in heavier,biodegr...For our ancestors, oil seeps were both a fascination and a resource but as the planet's reserves of high quality low density oil becomes increasingly depleted, so there is now a renewed interest in heavier,biodegraded oils such as those encountered in terrestrial seeps. One such seep is Pitch Lake in the Caribbean island of Trinidad, which is the largest natural deposit of asphalt in the world. At the northern end of the Caribbean, oil emerges along a tectonic contact on the island on Cuba. The sources of the oils from these seeps are relatively recent and both are subject to intense weathering due to the tropical conditions. When analysed by gas chromatography(GC) both oils appear as unresolved complex mixtures(UCM) and show a very high degree of biodegradation thus presenting an analytical challenge. In this case study, these two Caribbean seep oils were analysed by comprehensive two dimensional GC with time of flight mass spectrometry(GC×GC-TOFMS) to expose many thousands of the individual compounds that comprise the UCM. The high chromatographic resolution of the GC×GC-TOFMS produced good quality mass spectra allowing many compounds including molecular fossil ‘biomarkers' to be identified. Compound classes included diamondoid hydrocarbons, demethylated hopanes and secohopanes, mono-and tri-aromatic steroids. D-ring aromatised structures of the 8,14-seco-hopanes,including demethylated forms were present in both oils but further demethylation, probably at position C-25 during biodegradation, was only observed in the Pitch Lake oil. Many polycyclic aromatic hydrocarbons(PAHs) were absent although the fungal-derived pentacyclic PAH perylene was present in both oils. The presence of the angiosperm biomarker lupane in the Pitch Lake oil constrained the age to the Late Cretaceous. The higher degree of biodegradation observed in the Cuban oil was likely due to relatively slow anaerobic processes whereas oil within Pitch Lake was probably subject to additional more rapid aerobic metabolism within the lake.展开更多
An analytical method for quantifying biomarker compounds of the sterane and the hopane existing in saturated hydrocarbons has been established by using comprehensive two-dimensional gas chromatography-flame ionization...An analytical method for quantifying biomarker compounds of the sterane and the hopane existing in saturated hydrocarbons has been established by using comprehensive two-dimensional gas chromatography-flame ionization detector(GC×GC-FID) with optimized operating parameters. The new method achieves the quantification by using a GC×GC-FID system which is able to completely separate steranes from hopanes. The data obtained by the new method are of good repeatability and reliability. Compared with the original data, the relative standard deviations(RSDs) of 12 reference compounds are less than 5%. The RSDs of the quantitative results of the biomarkers based on seven separate analyses are also less than 5%. Compared with the traditional method of gas chromatography-mass spectrometry(GC-MS), the new method has a number of advantages, such as common internal standards(ISs), high resolution, no co-eluting peak, and no interference caused by diagnostic ion peaks. The new method provides petroleum geologists with an effective and scientific means in future researches.展开更多
The main reservoirs of Majiang fossil deposits consist of the Silurian Wengxiang group,dominantly sandstones,and the Ordovician Honghuayuan formation,dominantly carbonate rocks,and the Lower Cambrian Niutitang Formati...The main reservoirs of Majiang fossil deposits consist of the Silurian Wengxiang group,dominantly sandstones,and the Ordovician Honghuayuan formation,dominantly carbonate rocks,and the Lower Cambrian Niutitang Formation mudstones serve as the major source rocks.Thermochemical sulfate reduction(TSR)might have taken place in the Paleozoic marine carbonate oil pools,as indicated by high concentrations of dibenzothiophenes in the extracts(MDBT=0.27 4.32 g/g extract,and MDBT/MPH=0.71 1.38).Hydrocarbons in the Pojiaozhai Ordovician carbonate reservoirs have undergone severe TSR and are characterized by higher quantities of diamondoids and MDBT and heavier isotopic values(13C=28.4‰).The very large amounts of dibenzothiophenes might be products of reactions between biphenyls and sulfur species associated with TSR.展开更多
基金funded by the Major State Basic Research Development Program of China(973 project,Grant No.2012CB214803)National Science and Technology Major Project of China(Grant No. 2016ZX05003-005)National Natural Science Foundation of China(Grant Nos.41322017 and 41472100)
文摘As a new technology of analyzing crude oils, comprehensive two-dimensional gas chromatography cou- pled with time-of-flight mass spectrometry （GCxGC- TOFMS） has received much research attention. Here we present a case study in the Junggar Basin of NW China. Results show that the hydrocarbons, including saturates and aromatics, were all well-separated without large co- elution, which cannot be realized by conventional one-dimensional GC-MS. The GC×GC technique is especially effective for analyzing aromatics and low-to-middle- molecular-weight hydrocarbons, such as diamondoids. The geochemical characteristics of crude oils in the study area were investigated through geochemical parameters extracted by GC×GC-TOFMS, improving upon the understanding obtained by GC-MS. Thus, the work here represents a new successful application of GC×GC- TOFMS, showing its broad usefulness in petroleum geochemistry.
文摘For our ancestors, oil seeps were both a fascination and a resource but as the planet's reserves of high quality low density oil becomes increasingly depleted, so there is now a renewed interest in heavier,biodegraded oils such as those encountered in terrestrial seeps. One such seep is Pitch Lake in the Caribbean island of Trinidad, which is the largest natural deposit of asphalt in the world. At the northern end of the Caribbean, oil emerges along a tectonic contact on the island on Cuba. The sources of the oils from these seeps are relatively recent and both are subject to intense weathering due to the tropical conditions. When analysed by gas chromatography(GC) both oils appear as unresolved complex mixtures(UCM) and show a very high degree of biodegradation thus presenting an analytical challenge. In this case study, these two Caribbean seep oils were analysed by comprehensive two dimensional GC with time of flight mass spectrometry(GC×GC-TOFMS) to expose many thousands of the individual compounds that comprise the UCM. The high chromatographic resolution of the GC×GC-TOFMS produced good quality mass spectra allowing many compounds including molecular fossil ‘biomarkers' to be identified. Compound classes included diamondoid hydrocarbons, demethylated hopanes and secohopanes, mono-and tri-aromatic steroids. D-ring aromatised structures of the 8,14-seco-hopanes,including demethylated forms were present in both oils but further demethylation, probably at position C-25 during biodegradation, was only observed in the Pitch Lake oil. Many polycyclic aromatic hydrocarbons(PAHs) were absent although the fungal-derived pentacyclic PAH perylene was present in both oils. The presence of the angiosperm biomarker lupane in the Pitch Lake oil constrained the age to the Late Cretaceous. The higher degree of biodegradation observed in the Cuban oil was likely due to relatively slow anaerobic processes whereas oil within Pitch Lake was probably subject to additional more rapid aerobic metabolism within the lake.
文摘An analytical method for quantifying biomarker compounds of the sterane and the hopane existing in saturated hydrocarbons has been established by using comprehensive two-dimensional gas chromatography-flame ionization detector(GC×GC-FID) with optimized operating parameters. The new method achieves the quantification by using a GC×GC-FID system which is able to completely separate steranes from hopanes. The data obtained by the new method are of good repeatability and reliability. Compared with the original data, the relative standard deviations(RSDs) of 12 reference compounds are less than 5%. The RSDs of the quantitative results of the biomarkers based on seven separate analyses are also less than 5%. Compared with the traditional method of gas chromatography-mass spectrometry(GC-MS), the new method has a number of advantages, such as common internal standards(ISs), high resolution, no co-eluting peak, and no interference caused by diagnostic ion peaks. The new method provides petroleum geologists with an effective and scientific means in future researches.
基金supported by the State Key Project of Petroleum(2008ZX05005-001-009HZ)the National Natural Science Foundation of China(41172126)+1 种基金the State Key Laboratory of Petroleum Resources and Prospecting(PRP2010-01)the Science Foundation of China University of Petroleum(LLYJ-2011-05 and KYJJ-2012-01-01)
文摘The main reservoirs of Majiang fossil deposits consist of the Silurian Wengxiang group,dominantly sandstones,and the Ordovician Honghuayuan formation,dominantly carbonate rocks,and the Lower Cambrian Niutitang Formation mudstones serve as the major source rocks.Thermochemical sulfate reduction(TSR)might have taken place in the Paleozoic marine carbonate oil pools,as indicated by high concentrations of dibenzothiophenes in the extracts(MDBT=0.27 4.32 g/g extract,and MDBT/MPH=0.71 1.38).Hydrocarbons in the Pojiaozhai Ordovician carbonate reservoirs have undergone severe TSR and are characterized by higher quantities of diamondoids and MDBT and heavier isotopic values(13C=28.4‰).The very large amounts of dibenzothiophenes might be products of reactions between biphenyls and sulfur species associated with TSR.
