The experimental data yielded by Rock-Eval pyrolysis, kerogen atomic H/C, Py-GC and gold-tube sealing thermal simulation on the marine Cambrian-Ordovician source rock from the Tarim Basin revealed that the upper limit...The experimental data yielded by Rock-Eval pyrolysis, kerogen atomic H/C, Py-GC and gold-tube sealing thermal simulation on the marine Cambrian-Ordovician source rock from the Tarim Basin revealed that the upper limit of maturity for natural gas generation or the "deadline of gas generation" for marine types I and II kerogens is equal to 3.0% of vitrinite reflectance (Ro); while the "deadline of gas generation" for type III kerogens typically like coals is as high as 10% Ro. Thus, different organic matter has obviously different utmost maturities for gas generation. The mass-balance calculation by kerogen elements showed that when Ro>1.5%, the utmost amount of gas generation for the marine type II kerogen is less than 185 m3/t TOC, accounting for less than 30% of its total hydrocarbon generative potential; when Ro>2.0%, it becomes 110 m3/t TOC, less than 20% of the total hydrocarbon generative potential. The amount of the gas generative potential obtained by Rock-Eval is only around one tenth of the calculated value by the mass balance of kerogen elements at the same thermal evolutionary stage, while those by Py-GC and gold-tube sealing simulation are intervenient between the above two. The utmost of gas generative potential at the over 1.3% Ro stage is around 60―90 m3/t TOC, therefore, the amount of gas generation obtained by Rock-Eval is the minimum of gas generative potential, while that by the mass-balance calculation of kerogen elements is the maximum that the actual amount of gas generation should not exceed.展开更多
Gas washing has been known in the Tazhong area of the Tarim Basin,but its quantitative assessment has not yet been reported.Here the influence of gas washing fractionation in the area was discussed based on the gas ch...Gas washing has been known in the Tazhong area of the Tarim Basin,but its quantitative assessment has not yet been reported.Here the influence of gas washing fractionation in the area was discussed based on the gas chromatogram data of 68 oils and the results of the mixing experiments of a black oil and a condensate.The results show that the intensity of gas washing fractionation decreased generally from northern to southern part and vertically from deep reservoirs to shallow reservoirs.The gas washing fractionation was mainly controlled by fault systems in this area,with the increase of n-alkane mass depletion positively correlated to the number and scale of faults.Gas washing fractionation appears to have affected the hydrocarbon property,and as a result the diversity of the crude oils is markedly controlled by gas washing.In addition,the occurrence of waxy oil in this area may be resulted from multiple factors including gas washing,mixed filling and migration fractionation.展开更多
Hydrocarbons, include heavy oils, normal oils, waxy oils and light oils, condensate oils and gases were all found in Lunnan Oilfield, the occurrences of hydrocarbons with complicated physical properties indicates a co...Hydrocarbons, include heavy oils, normal oils, waxy oils and light oils, condensate oils and gases were all found in Lunnan Oilfield, the occurrences of hydrocarbons with complicated physical properties indicates a complicated distribution of reservoirs. By the drilling data, the distribution pattern had been found that, in plan view, the density of crude oils in the western part is heavier than that of oils in the eastern part in Lunnan region, namely the crude oils were mainly found in the western part while the natural gases were mainly found in the eastern, which shows that an obvious differentiation in the east and west part was presented in the Lunnan region. Furthermore, in vertical view, the light hydrocarbons were mainly found in the Carboniferous reservoir while the heavier hydrocarbons were mainly found in the Ordovician and Triassic reservoirs. By analysis of the semi-logarithm distribution of n-alkanes, biomarker ratios and stable carbon isotopic compositions of crude oils, we have found展开更多
The saline lacustrine deposit of the Oligocene Lower Ganchaigou Formation is the main source rock for the Western Qaidam Basin,NW China.In this study,abundant highly branched isoprenoids with 25 carbon atoms (C25HBI) ...The saline lacustrine deposit of the Oligocene Lower Ganchaigou Formation is the main source rock for the Western Qaidam Basin,NW China.In this study,abundant highly branched isoprenoids with 25 carbon atoms (C25HBI) were detected in the upper section of the Lower Ganchaigou Formation.C25HBI is a biomarker for diatoms,and can provide information regarding biogeochemical processes during production and preservation of sedimentary organic matter.The carbon isotopic values of C25HBI in these source rocks were in the range of-18‰ to-20‰.The relative enrichment in 13C of C25HBI suggests that these isoprenoids were derived from diatom blooms.In this case,the diatoms used HCO3-as an additional carbon source to dissolved CO2 in water column due to their high biological productivity.Conversely,the diatom blooms indicated an abundant nutrient supply to the environment and high primary productivity.Thus,the occurrence of 13C-enriched C25HBI could be an ideal marker for good source rocks.The decreased concentration of CO2(aq) in the water column induced by diatom blooms can result in an enrichment in 13C of organic matter synthesized by primary producers.This may be a possible reason for the occurrence of 13C-enriched organic matter in the Cenozoic source rocks of the Western Qaidam Basin.Previous studies have shown that the high carbon number n-alkanes sourced from diatoms have no carbon preference.Hence,the sources of n-alkanes in regional source rocks are complex,and should be considered when discussing the sources of organic matter in future studies.展开更多
Although the distribution of mono-,di-and trimethylated 2-methyl-2-(4,8,12-Trimethyltrideeyl) chromans(MTTCs) is well understood as an indicator of water salinity,their origin and formation mechanism are still ambiguo...Although the distribution of mono-,di-and trimethylated 2-methyl-2-(4,8,12-Trimethyltrideeyl) chromans(MTTCs) is well understood as an indicator of water salinity,their origin and formation mechanism are still ambiguous and under debate.In this paper,abnormally high levels of MTTCs were detected in Cenozoic saline lacustrine source rocks from the Western Qaidam Basin.Using a two-step column chromatography method,the MTTCs and naphthalenes were separated from other aromatic compounds and concentrated in one fraction,so that the stable carbon isotope compositions of these compounds could be accurately measured.Similar carbon isotope ratios for the mono-,di-and trimethylated 2-methyl-2-(4,8,12-Trimethyltrideeyl) chromans in a given sample suggest the MTTCs may share the same biological source(s).The MTTCs from the Western Qaidam Basin have similar carbon isotope compositions to primary producer-derived pristane and phytane.However,the ? 13C values for the MTTCs showed significant differences with other primary producers-derived biomarkers(e.g.C27 and C29 steranes),probably indicating a distinct microalgae source from specific niches for the MTTC compounds.We speculate that the MTTCs distribution patterns may be controlled by the water chemistry dynamics in niches,which,in turn,is affected by hypersaline bottom water.展开更多
To date, questions remain as to how to differentiate between coal- and interbedded shale-sourced oils in coal measures. Based on the hypothesis that δ13C value of sedimentary organic matter is controlled by the depos...To date, questions remain as to how to differentiate between coal- and interbedded shale-sourced oils in coal measures. Based on the hypothesis that δ13C value of sedimentary organic matter is controlled by the depositional environment and productivities of biota grown in such depositional setting, this note examines compound specific carbon isotopic profiles from coal and interbedded shale extracts using the gas chromatography-isotope ratio mass spec-trometry technique (GC/IRMS). The results show that compound specific carbon isotope values from coal extracts are enriched in 13C relative to that of interbedded shale extracts, and provide useful information in characterizing coal- and interbedded shale-sourced oils in coal measures. An example for its successful application from the Turpan Basin, Northwestern China is presented.展开更多
Some typical coal and maceral samples are selected for oil and gas-generatingsystematic thermal simulation experiments, Rock-Eval, GC and GC-MS analyses. Results cause productivity curves of extracts and gaseous, ligh...Some typical coal and maceral samples are selected for oil and gas-generatingsystematic thermal simulation experiments, Rock-Eval, GC and GC-MS analyses. Results cause productivity curves of extracts and gaseous, light, liquid as well as total hydrocarbon. Effects of macerals and maturation on hydrocarbon productivities and compositions are synthetically discussed. Evaluation indexes and plan on coal-generated oil and gas in bituminous coal rank are suggested according to the data from experiments and analyses.展开更多
After the detection of the 1,20,21-C29 long-chain triol in some sediments and freshwater pteridophytes, in this study a new homologous long-chain triol, 1,3,4-C27-29, is detected for the first time in the Site4B core ...After the detection of the 1,20,21-C29 long-chain triol in some sediments and freshwater pteridophytes, in this study a new homologous long-chain triol, 1,3,4-C27-29, is detected for the first time in the Site4B core sediment in the northern South China Sea. The hydroxyl location and length of the carbon chain of this newly discovered triol differ from those of 1,20,21-C29 triol. The test results of its molecular distribution and individual carbon isotope reveal that 1,3,4-C29triol has a good correlation with n-C26-30 even carbon-numbered long-chain fatty alcohols, with R2 （n=68） values of 0.905, 0.929 and 0.903, respectively, and its carbon isotope composition, at -32.3%o_1.9%o, is similar to that of rt-C26.30, at -29.13%o^0.87%o, -32.98%o^1.28%o, and -32.98%o^1.28%o. 1,3,4-C29 triol from the Site4B core sediment and terrigenous long-chain fatty alcohol （n-C26.34） show highly consistent distribution trends in the entire section; thus, the former could serve as a proxy indicator of the terrigenous input. Considering that the 1,20,21-C29 triol in previous research belongs to Azolla, which are fresh water pteridophytes, the 1,3,4-C27-29 triol identified in this study might have similar biogenetic derivation. Thus, determination of its biogenic area and growing environment could provide potential organic geochemical evidence supporting the terrigenous input and source in the northern South China Sea.展开更多
By using fluorescence lifetime image microscope （FLIM） and time-correlated single photon counting （TCSPC） technique, we measured fluorescence lifetime of crude oils with density of 0.9521-0.7606 g/cm3 and multiple...By using fluorescence lifetime image microscope （FLIM） and time-correlated single photon counting （TCSPC） technique, we measured fluorescence lifetime of crude oils with density of 0.9521-0.7606 g/cm3 and multiple petroleum inclusions from Tazhong uplift of Tarim Basin. As indicated by the test results, crude oil density is closely correlated with average fluorescence lifetime following the regression equation Y=-0.0319X＋0.9411, which can thus be used to calculate density of oil inclusions in relation to fluorescence lifetime and density of corresponding surface crude. For type A oil inclusions showing brown-yellow fluorescence from Tazhong 1 well in Tarim Basin, their average fluorescence lifetime was found to be 2.144-2.765 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.852-0.873 g/cm3, indicating that they are matured oil inclusions trapped at earlier stage ofoil formation. For type B oil inclusions with light yellow-white fluorescence, their average fluorescence lifetime was found to be 4.0294.919 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.784-0.812 g/cm3, indicating that they are higher matured oil inclusions trapped at the second stage of oil formation. For type C oil inclusions showing light blue-green fluorescence, their average fluorescence lifetime was found to be 5.0634.168 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.743-0.779 g/cm3, indicating that they are highly-matured light oil inclusions trapped at the third stage of oil formation.展开更多
It is a challenge to determine the source and genetic relationship of condensate, waxy and heavy oils in one given complicated petroliferous area, where developed multiple sets of source rocks with different maturity ...It is a challenge to determine the source and genetic relationship of condensate, waxy and heavy oils in one given complicated petroliferous area, where developed multiple sets of source rocks with different maturity and various chemical features.The central part of southern margin of Junggar Basin, NW China is such an example where there are condensates, light oils, normal density oils, heavy crude oils and natural gases. The formation mechanism of condensates has been seriously debated for long time;however, no study has integrated it with genetic types of waxy and heavy oils. Taking the central part of southern margin of Junggar Basin as a case, this study employs geological and geochemical methods to determine the formation mechanism of condensates,waxy and heavy oils in a complicated petroliferous area, and reveals the causes and geochemical processes of the co-occurrence of different types of crude oils in this region. Based on detailed geochemical analyses of more than 40 normal crude oils, light oils,condensates and heavy oils, it is found that the condensates are dominated by low carbon number n-alkanes and enriched in light naphthenics and aromatic hydrocarbons. Heptane values of these condensates range from 19% to 21%, isoheptane values from1.9 to 2.1, and toluene/n-heptane ratios from 1.5 to 2.0. The distribution of n-alkanes in the condensates presents a mirror image with high density waxy crude oils and heavy oils. Combined with the oil and gas-source correlations of the crude oils, condensates and natural gas, it is found that the condensates are product of evaporative fractionation and/or phase-controlled fractionation of reservoir crude oils which were derived from mature Cretaceous lacustrine source rocks in the relatively early stage. The waxy oils are the intermediate products of evaporative fractionation and/or phase-controlled fractionation of reservoir crude oils, while the heavy oils are in-situ residuals. Therefore, evaporative fractionation and/or phase-controlled fractionation would account for the formation of the condensate, light oil, waxy oil and heavy oil in the central part of southern margin of Junggar Basin, resulting in a great change of the content in terms of light alkanes, naphthenics and aromatics in condensates, followed by great uncertainties of toluene/n-heptane ratios due to migration and re-accumulation. The results suggest that the origin of the condensate cannot be simply concluded by its ratios of toluene/n-heptane and n-heptane/methylcyclohexane on the Thompson's cross-plot, it should be comprehensively determined by the aspects of geological background, thermal history of source rocks and petroleum generation,physical and chemical features of various crude oils and natural gas, vertical and lateral distribution of various crude oils in the study area.展开更多
Due to the importance of the Gloeocapsomorpha Prisca(G.prisca)-enriched source rocks,which belong to Kukersite-type source rocks in the Lower Paleozoic Ordovician strata,it has received great attentions during the pet...Due to the importance of the Gloeocapsomorpha Prisca(G.prisca)-enriched source rocks,which belong to Kukersite-type source rocks in the Lower Paleozoic Ordovician strata,it has received great attentions during the petroleum exploration as to whether there are the Kukersite-type source rocks developed in the major hydrocarbon source strata of the Upper and Middle Ordovician in the Tarim Basin.Using pyrolysis-gas chromatography-mass spectrography to analyse kerogens from source rocks in the limemud mound with moderate maturity,study reveals that there are the Kukersite-type source rocks in the Ordovician strata of the Tarim Basin.The pyrolysis products showed a low content of>n-C19normal alkanes with a significant odd-even predominance between n-C13and n-C17,long-chain alky substituted alkylbenzene and alkylthiophene isomers and distinctive distribution of 5-Nalkyl-1,3-Benzenediol and its homologous.Based on the geographic environment characteristics of G.Prisca,the molecular distributions of crude oil from the Lower Paleozoic petroleum systems in the Tarim Basin and characteristics of kerogen pyrolysis products from the Middle and Upper Ordovician source rocks,the results suggested that it is less possible to develop the G.Prisca-enriched Kukersite-type source rocks in the major hydrocarbon source rocks in the Middle and Upper Ordovician strata in the Tarim Basin.However,the benthic macroalga and planktonic algae-enriched source rocks are the main contributors.展开更多
This study investigated the composition of long-chain alkyl diols, triols, sec-alcohols, hydroxyl acids, and other hydroxylated compounds in Azolla imbricata and compared the organic alcohol components of Azolla filic...This study investigated the composition of long-chain alkyl diols, triols, sec-alcohols, hydroxyl acids, and other hydroxylated compounds in Azolla imbricata and compared the organic alcohol components of Azolla filiculoides, Azolla microphylla, and South China Sea （SCS） sediments in order to investigate the possible indication of Azolla being the biological source of diols and triols in SCS sediment. Large amounts of diols, monohydroxy acids, and sec-alcohols with internal hydroxy groups at ω20 were detected in the three types of Azolla. Among these, 1,ω20-diol and ω20-hydroxy acid exhibited strong even-odd predominance distribution, whereas co20-sec-alcohol exhibited strong odd-even predominance distribution. In addition, small amounts of diols, triols, and dihydroxy acids with internal hydroxy groups at 9, 10 or ω9, ω 10 were detected, among which the chain length of C29 was predominate. Compounds having similar structures as those in Azolla reflected a similar biosynthetic pathway： ω20-hydroxy acid exhibiting even-odd predominance distribution is decarboxylated to ω20-sec-alcohol exhibiting odd-even predominance distribution and converted to 1, ω20-diol with even-odd predominance distribution by acyl reduction; ω9,ω10-hydroxy acid is converted to 1,20,21（1, ω9, ω10）-triol by acyl reduction, and then converted to 9,10-diol by hydrogenation and dehydration. The alcohol components in A. imbricata were clearly not the biological source of 1,13/1,14/1,15-C28, 30, 32 diols and 1,3,4-C27.29 triols in the SCS sediment. Certain marine diatoms might be the source of 1,14-C28.30 diol in inshore sediment, but the biological source of diols and triols in the SCS sediment requires further investigation.展开更多
The semi-closed pyrolysis simulation system under constant pressure was conducted to explore the characteristics and mechanisms of hydrocarbon generation from Xiamaling Formation shale in Xiahuayuan,North China.The ex...The semi-closed pyrolysis simulation system under constant pressure was conducted to explore the characteristics and mechanisms of hydrocarbon generation from Xiamaling Formation shale in Xiahuayuan,North China.The experiment results indicate the oil generated by the Xiamaling Formation shale in oil window should be classified as "aromatic-intermediate" type,whereas the decreasing of dry coefficient can be ascribed to the cracking of residual bitumen in source rock in the stage of high to post maturity.The amount of hydrocarbon gas generated from residual bitumen can be up to 1-2 m3 per ton rock in high to post mature stage by calculating hydrogen contents in the kerogen,the expelled hydrocarbon,and the residual hydrocarbon.This reveals the importance of residual bitumen as a gas source during high to post mature stage of the kerogen evolution,and also as the broad exploration prospect of these gases.This research highlights the attention should be paid to oil/gas reservoirs sourced from residual bitumen of organic-rich source rock in high mature stage,even the primary oil/gas reservoirs considered as the main exploration targets in middle-upper Proterozoic sediments of North China.展开更多
Using molecular geochemical data from infrared spectrometer and pyrolysis gas chromatography-mass spectrometry, this paper investigates the petroleum generation characteristics of Jurassic coal measures from Kuche dep...Using molecular geochemical data from infrared spectrometer and pyrolysis gas chromatography-mass spectrometry, this paper investigates the petroleum generation characteristics of Jurassic coal measures from Kuche depression, Tarim Basin, NW China. The results showed that the Jurassic coaly rocks with medium maturity (R0%: 0.8-1.1) were enriched in gas-prone functionalities (-CH3) and low molecular weight pyrolysates (【nC21), indicating that the coaly rocks from Kuche depression were gas/condensate prone at the stages of middle to high maturation, and it was further supported by the oil/source correlation from well Yinan 2 in this region.展开更多
基金the Natural Gas Project of the National "973" Basic Research Devel-opment Planning (Grant No. 2001CB209100)"the Tenth Five-Year Plan" Na-tional Scientific & Technological Programs (Grant No. 2004BA616A020-01-01)
文摘The experimental data yielded by Rock-Eval pyrolysis, kerogen atomic H/C, Py-GC and gold-tube sealing thermal simulation on the marine Cambrian-Ordovician source rock from the Tarim Basin revealed that the upper limit of maturity for natural gas generation or the "deadline of gas generation" for marine types I and II kerogens is equal to 3.0% of vitrinite reflectance (Ro); while the "deadline of gas generation" for type III kerogens typically like coals is as high as 10% Ro. Thus, different organic matter has obviously different utmost maturities for gas generation. The mass-balance calculation by kerogen elements showed that when Ro>1.5%, the utmost amount of gas generation for the marine type II kerogen is less than 185 m3/t TOC, accounting for less than 30% of its total hydrocarbon generative potential; when Ro>2.0%, it becomes 110 m3/t TOC, less than 20% of the total hydrocarbon generative potential. The amount of the gas generative potential obtained by Rock-Eval is only around one tenth of the calculated value by the mass balance of kerogen elements at the same thermal evolutionary stage, while those by Py-GC and gold-tube sealing simulation are intervenient between the above two. The utmost of gas generative potential at the over 1.3% Ro stage is around 60―90 m3/t TOC, therefore, the amount of gas generation obtained by Rock-Eval is the minimum of gas generative potential, while that by the mass-balance calculation of kerogen elements is the maximum that the actual amount of gas generation should not exceed.
基金Supported by National Basic Research Program of China (Grant No.2006CB202303)the National Natural Science Foundation of China (Grant No.40672091)
文摘Gas washing has been known in the Tazhong area of the Tarim Basin,but its quantitative assessment has not yet been reported.Here the influence of gas washing fractionation in the area was discussed based on the gas chromatogram data of 68 oils and the results of the mixing experiments of a black oil and a condensate.The results show that the intensity of gas washing fractionation decreased generally from northern to southern part and vertically from deep reservoirs to shallow reservoirs.The gas washing fractionation was mainly controlled by fault systems in this area,with the increase of n-alkane mass depletion positively correlated to the number and scale of faults.Gas washing fractionation appears to have affected the hydrocarbon property,and as a result the diversity of the crude oils is markedly controlled by gas washing.In addition,the occurrence of waxy oil in this area may be resulted from multiple factors including gas washing,mixed filling and migration fractionation.
文摘Hydrocarbons, include heavy oils, normal oils, waxy oils and light oils, condensate oils and gases were all found in Lunnan Oilfield, the occurrences of hydrocarbons with complicated physical properties indicates a complicated distribution of reservoirs. By the drilling data, the distribution pattern had been found that, in plan view, the density of crude oils in the western part is heavier than that of oils in the eastern part in Lunnan region, namely the crude oils were mainly found in the western part while the natural gases were mainly found in the eastern, which shows that an obvious differentiation in the east and west part was presented in the Lunnan region. Furthermore, in vertical view, the light hydrocarbons were mainly found in the Carboniferous reservoir while the heavier hydrocarbons were mainly found in the Ordovician and Triassic reservoirs. By analysis of the semi-logarithm distribution of n-alkanes, biomarker ratios and stable carbon isotopic compositions of crude oils, we have found
基金supported by the National Natural Science Foundation of China (40972093)the National Special Program of Oil and Gas in China (2008ZX05008-002-001)+1 种基金the Natural Science Foundation of Zhejiang Province (R5080124)the Fundamental Research Funds for the Central Universities
文摘The saline lacustrine deposit of the Oligocene Lower Ganchaigou Formation is the main source rock for the Western Qaidam Basin,NW China.In this study,abundant highly branched isoprenoids with 25 carbon atoms (C25HBI) were detected in the upper section of the Lower Ganchaigou Formation.C25HBI is a biomarker for diatoms,and can provide information regarding biogeochemical processes during production and preservation of sedimentary organic matter.The carbon isotopic values of C25HBI in these source rocks were in the range of-18‰ to-20‰.The relative enrichment in 13C of C25HBI suggests that these isoprenoids were derived from diatom blooms.In this case,the diatoms used HCO3-as an additional carbon source to dissolved CO2 in water column due to their high biological productivity.Conversely,the diatom blooms indicated an abundant nutrient supply to the environment and high primary productivity.Thus,the occurrence of 13C-enriched C25HBI could be an ideal marker for good source rocks.The decreased concentration of CO2(aq) in the water column induced by diatom blooms can result in an enrichment in 13C of organic matter synthesized by primary producers.This may be a possible reason for the occurrence of 13C-enriched organic matter in the Cenozoic source rocks of the Western Qaidam Basin.Previous studies have shown that the high carbon number n-alkanes sourced from diatoms have no carbon preference.Hence,the sources of n-alkanes in regional source rocks are complex,and should be considered when discussing the sources of organic matter in future studies.
基金supported by the National Natural Science Foundation of China (40972093)the National Special Program of Oil and Gas in China (2011ZX05008-002)+1 种基金the Natural Science Foundation of Zhejiang Province (R5080124)the Fundamental Research Funds for the Central Universities
文摘Although the distribution of mono-,di-and trimethylated 2-methyl-2-(4,8,12-Trimethyltrideeyl) chromans(MTTCs) is well understood as an indicator of water salinity,their origin and formation mechanism are still ambiguous and under debate.In this paper,abnormally high levels of MTTCs were detected in Cenozoic saline lacustrine source rocks from the Western Qaidam Basin.Using a two-step column chromatography method,the MTTCs and naphthalenes were separated from other aromatic compounds and concentrated in one fraction,so that the stable carbon isotope compositions of these compounds could be accurately measured.Similar carbon isotope ratios for the mono-,di-and trimethylated 2-methyl-2-(4,8,12-Trimethyltrideeyl) chromans in a given sample suggest the MTTCs may share the same biological source(s).The MTTCs from the Western Qaidam Basin have similar carbon isotope compositions to primary producer-derived pristane and phytane.However,the ? 13C values for the MTTCs showed significant differences with other primary producers-derived biomarkers(e.g.C27 and C29 steranes),probably indicating a distinct microalgae source from specific niches for the MTTC compounds.We speculate that the MTTCs distribution patterns may be controlled by the water chemistry dynamics in niches,which,in turn,is affected by hypersaline bottom water.
基金This work was supported by the Chinese Academy of Sciences (Grant No. KZ951-B1-412).
文摘To date, questions remain as to how to differentiate between coal- and interbedded shale-sourced oils in coal measures. Based on the hypothesis that δ13C value of sedimentary organic matter is controlled by the depositional environment and productivities of biota grown in such depositional setting, this note examines compound specific carbon isotopic profiles from coal and interbedded shale extracts using the gas chromatography-isotope ratio mass spec-trometry technique (GC/IRMS). The results show that compound specific carbon isotope values from coal extracts are enriched in 13C relative to that of interbedded shale extracts, and provide useful information in characterizing coal- and interbedded shale-sourced oils in coal measures. An example for its successful application from the Turpan Basin, Northwestern China is presented.
文摘Some typical coal and maceral samples are selected for oil and gas-generatingsystematic thermal simulation experiments, Rock-Eval, GC and GC-MS analyses. Results cause productivity curves of extracts and gaseous, light, liquid as well as total hydrocarbon. Effects of macerals and maturation on hydrocarbon productivities and compositions are synthetically discussed. Evaluation indexes and plan on coal-generated oil and gas in bituminous coal rank are suggested according to the data from experiments and analyses.
基金In addition,gratitude is expressed to the National Natural Science Foundation of China(Grant Nos.41303067,41103043&41273022)Funds of Chinese Academy of Sciences for Key Topics in Innovation Engineering(Grant No.KGZD-EW-301)+2 种基金State Key Laboratory of Organic Geochemistry Open Research Fund(Grant No.OGL-201209)CNPC-CAS Science and Technology Cooperation Project(Grant No.2015A-4813)the international partnership project team of Innovation of the Chinese Academy of Sciences for providing financial support
文摘After the detection of the 1,20,21-C29 long-chain triol in some sediments and freshwater pteridophytes, in this study a new homologous long-chain triol, 1,3,4-C27-29, is detected for the first time in the Site4B core sediment in the northern South China Sea. The hydroxyl location and length of the carbon chain of this newly discovered triol differ from those of 1,20,21-C29 triol. The test results of its molecular distribution and individual carbon isotope reveal that 1,3,4-C29triol has a good correlation with n-C26-30 even carbon-numbered long-chain fatty alcohols, with R2 （n=68） values of 0.905, 0.929 and 0.903, respectively, and its carbon isotope composition, at -32.3%o_1.9%o, is similar to that of rt-C26.30, at -29.13%o^0.87%o, -32.98%o^1.28%o, and -32.98%o^1.28%o. 1,3,4-C29 triol from the Site4B core sediment and terrigenous long-chain fatty alcohol （n-C26.34） show highly consistent distribution trends in the entire section; thus, the former could serve as a proxy indicator of the terrigenous input. Considering that the 1,20,21-C29 triol in previous research belongs to Azolla, which are fresh water pteridophytes, the 1,3,4-C27-29 triol identified in this study might have similar biogenetic derivation. Thus, determination of its biogenic area and growing environment could provide potential organic geochemical evidence supporting the terrigenous input and source in the northern South China Sea.
基金supported by the National Natural Science Foundation of China(Grant Nos.41321002,41402116)
文摘By using fluorescence lifetime image microscope （FLIM） and time-correlated single photon counting （TCSPC） technique, we measured fluorescence lifetime of crude oils with density of 0.9521-0.7606 g/cm3 and multiple petroleum inclusions from Tazhong uplift of Tarim Basin. As indicated by the test results, crude oil density is closely correlated with average fluorescence lifetime following the regression equation Y=-0.0319X＋0.9411, which can thus be used to calculate density of oil inclusions in relation to fluorescence lifetime and density of corresponding surface crude. For type A oil inclusions showing brown-yellow fluorescence from Tazhong 1 well in Tarim Basin, their average fluorescence lifetime was found to be 2.144-2.765 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.852-0.873 g/cm3, indicating that they are matured oil inclusions trapped at earlier stage ofoil formation. For type B oil inclusions with light yellow-white fluorescence, their average fluorescence lifetime was found to be 4.0294.919 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.784-0.812 g/cm3, indicating that they are higher matured oil inclusions trapped at the second stage of oil formation. For type C oil inclusions showing light blue-green fluorescence, their average fluorescence lifetime was found to be 5.0634.168 ns, so the density of surface crude corresponding to crude trapping these oil inclusions is 0.743-0.779 g/cm3, indicating that they are highly-matured light oil inclusions trapped at the third stage of oil formation.
基金supported by the PetroChina Science and Technology Special Projects (Grant Nos. 06-10A-01-02, 2011A-0201, 2014A-0211 and 2016A-0202)
文摘It is a challenge to determine the source and genetic relationship of condensate, waxy and heavy oils in one given complicated petroliferous area, where developed multiple sets of source rocks with different maturity and various chemical features.The central part of southern margin of Junggar Basin, NW China is such an example where there are condensates, light oils, normal density oils, heavy crude oils and natural gases. The formation mechanism of condensates has been seriously debated for long time;however, no study has integrated it with genetic types of waxy and heavy oils. Taking the central part of southern margin of Junggar Basin as a case, this study employs geological and geochemical methods to determine the formation mechanism of condensates,waxy and heavy oils in a complicated petroliferous area, and reveals the causes and geochemical processes of the co-occurrence of different types of crude oils in this region. Based on detailed geochemical analyses of more than 40 normal crude oils, light oils,condensates and heavy oils, it is found that the condensates are dominated by low carbon number n-alkanes and enriched in light naphthenics and aromatic hydrocarbons. Heptane values of these condensates range from 19% to 21%, isoheptane values from1.9 to 2.1, and toluene/n-heptane ratios from 1.5 to 2.0. The distribution of n-alkanes in the condensates presents a mirror image with high density waxy crude oils and heavy oils. Combined with the oil and gas-source correlations of the crude oils, condensates and natural gas, it is found that the condensates are product of evaporative fractionation and/or phase-controlled fractionation of reservoir crude oils which were derived from mature Cretaceous lacustrine source rocks in the relatively early stage. The waxy oils are the intermediate products of evaporative fractionation and/or phase-controlled fractionation of reservoir crude oils, while the heavy oils are in-situ residuals. Therefore, evaporative fractionation and/or phase-controlled fractionation would account for the formation of the condensate, light oil, waxy oil and heavy oil in the central part of southern margin of Junggar Basin, resulting in a great change of the content in terms of light alkanes, naphthenics and aromatics in condensates, followed by great uncertainties of toluene/n-heptane ratios due to migration and re-accumulation. The results suggest that the origin of the condensate cannot be simply concluded by its ratios of toluene/n-heptane and n-heptane/methylcyclohexane on the Thompson's cross-plot, it should be comprehensively determined by the aspects of geological background, thermal history of source rocks and petroleum generation,physical and chemical features of various crude oils and natural gas, vertical and lateral distribution of various crude oils in the study area.
基金supported by the National Oil and Gas Special Fund of China(2011ZX05008-002-15)the National Natural Science Foundation ofChina(41172112)
文摘Due to the importance of the Gloeocapsomorpha Prisca(G.prisca)-enriched source rocks,which belong to Kukersite-type source rocks in the Lower Paleozoic Ordovician strata,it has received great attentions during the petroleum exploration as to whether there are the Kukersite-type source rocks developed in the major hydrocarbon source strata of the Upper and Middle Ordovician in the Tarim Basin.Using pyrolysis-gas chromatography-mass spectrography to analyse kerogens from source rocks in the limemud mound with moderate maturity,study reveals that there are the Kukersite-type source rocks in the Ordovician strata of the Tarim Basin.The pyrolysis products showed a low content of>n-C19normal alkanes with a significant odd-even predominance between n-C13and n-C17,long-chain alky substituted alkylbenzene and alkylthiophene isomers and distinctive distribution of 5-Nalkyl-1,3-Benzenediol and its homologous.Based on the geographic environment characteristics of G.Prisca,the molecular distributions of crude oil from the Lower Paleozoic petroleum systems in the Tarim Basin and characteristics of kerogen pyrolysis products from the Middle and Upper Ordovician source rocks,the results suggested that it is less possible to develop the G.Prisca-enriched Kukersite-type source rocks in the major hydrocarbon source rocks in the Middle and Upper Ordovician strata in the Tarim Basin.However,the benthic macroalga and planktonic algae-enriched source rocks are the main contributors.
基金the National Natural Science Foundation of China(Grant Nos.41303067,41103043&41273022)the Chinese Academy of Sciences Knowledge Innovation Project(Grant No.KGZD-EW-301)the PetroChina-Chinese Academy of Sciences Science and Technology Cooperation Project(Grant No.2015A-4813)
文摘This study investigated the composition of long-chain alkyl diols, triols, sec-alcohols, hydroxyl acids, and other hydroxylated compounds in Azolla imbricata and compared the organic alcohol components of Azolla filiculoides, Azolla microphylla, and South China Sea （SCS） sediments in order to investigate the possible indication of Azolla being the biological source of diols and triols in SCS sediment. Large amounts of diols, monohydroxy acids, and sec-alcohols with internal hydroxy groups at ω20 were detected in the three types of Azolla. Among these, 1,ω20-diol and ω20-hydroxy acid exhibited strong even-odd predominance distribution, whereas co20-sec-alcohol exhibited strong odd-even predominance distribution. In addition, small amounts of diols, triols, and dihydroxy acids with internal hydroxy groups at 9, 10 or ω9, ω 10 were detected, among which the chain length of C29 was predominate. Compounds having similar structures as those in Azolla reflected a similar biosynthetic pathway： ω20-hydroxy acid exhibiting even-odd predominance distribution is decarboxylated to ω20-sec-alcohol exhibiting odd-even predominance distribution and converted to 1, ω20-diol with even-odd predominance distribution by acyl reduction; ω9,ω10-hydroxy acid is converted to 1,20,21（1, ω9, ω10）-triol by acyl reduction, and then converted to 9,10-diol by hydrogenation and dehydration. The alcohol components in A. imbricata were clearly not the biological source of 1,13/1,14/1,15-C28, 30, 32 diols and 1,3,4-C27.29 triols in the SCS sediment. Certain marine diatoms might be the source of 1,14-C28.30 diol in inshore sediment, but the biological source of diols and triols in the SCS sediment requires further investigation.
基金supported by National Natural Science Foundation of China(Grant Nos.40972093 and 41172112)Natural Science Foundation of Zhejiang Province(Grant No.R5080124)+1 种基金Foundation of State Key Laboratory of Enhanced Oil Recoverythe Foundation of State Key Laboratory of Petroleum Resource and Prospecting(Grant No.2009001)
文摘The semi-closed pyrolysis simulation system under constant pressure was conducted to explore the characteristics and mechanisms of hydrocarbon generation from Xiamaling Formation shale in Xiahuayuan,North China.The experiment results indicate the oil generated by the Xiamaling Formation shale in oil window should be classified as "aromatic-intermediate" type,whereas the decreasing of dry coefficient can be ascribed to the cracking of residual bitumen in source rock in the stage of high to post maturity.The amount of hydrocarbon gas generated from residual bitumen can be up to 1-2 m3 per ton rock in high to post mature stage by calculating hydrogen contents in the kerogen,the expelled hydrocarbon,and the residual hydrocarbon.This reveals the importance of residual bitumen as a gas source during high to post mature stage of the kerogen evolution,and also as the broad exploration prospect of these gases.This research highlights the attention should be paid to oil/gas reservoirs sourced from residual bitumen of organic-rich source rock in high mature stage,even the primary oil/gas reservoirs considered as the main exploration targets in middle-upper Proterozoic sediments of North China.
文摘Using molecular geochemical data from infrared spectrometer and pyrolysis gas chromatography-mass spectrometry, this paper investigates the petroleum generation characteristics of Jurassic coal measures from Kuche depression, Tarim Basin, NW China. The results showed that the Jurassic coaly rocks with medium maturity (R0%: 0.8-1.1) were enriched in gas-prone functionalities (-CH3) and low molecular weight pyrolysates (【nC21), indicating that the coaly rocks from Kuche depression were gas/condensate prone at the stages of middle to high maturation, and it was further supported by the oil/source correlation from well Yinan 2 in this region.
