1991 Vol. 9, No. S1
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Display Method:
1991, 9(S1): 1-8.
Abstract:
This paper presents an overview on current thinking about sources, ages, and thermal histories of Chinese non-marine crude oils. Terrestrial source rocks, deposited under non-marine conditions in continental environments, have been divided into four major groups: Group A, sedimentary formations of big lake basins in the interior of the Chinese plate; Group B, lacustrine clastic formations in fault-bounded basins; Group C; salt lake evaporite- clastic formations in fault- bounded basins; and Gruop D, lagoonal- lacustrine volcano-clastic formations of intermontane basins. A number of representative crude oil samples were collected from the following four type of source rocks:(1) Lacustrine fresh-brackish water mudstones;(2) Saline to hypersaline mudstones;(3) Lacustrine dolomitic mudstones;(4) Lagoonal tufferous mudstones. The samples were analysed by GC and GC-MS to reveal the characteristic distributions of biological markers in their aliphatic fractions. The distribution of n-alkanes, isoprenoids, steranes and hopanoids as well as other biological marker compounds are discussed briefly. In terms of biological marker parameters of their aliphatic fractions, some immature to marginal mature oil samples sourced from hypersaline and saline mudstones are described. Immature or marginal mature crude oils occurred in shallow depth in Jianghan basin contain high amount of sulphur and organic sulphur compounds, especially abundant thiophene and thiolane homologues with remarkable even carbon number predominace.
This paper presents an overview on current thinking about sources, ages, and thermal histories of Chinese non-marine crude oils. Terrestrial source rocks, deposited under non-marine conditions in continental environments, have been divided into four major groups: Group A, sedimentary formations of big lake basins in the interior of the Chinese plate; Group B, lacustrine clastic formations in fault-bounded basins; Group C; salt lake evaporite- clastic formations in fault- bounded basins; and Gruop D, lagoonal- lacustrine volcano-clastic formations of intermontane basins. A number of representative crude oil samples were collected from the following four type of source rocks:(1) Lacustrine fresh-brackish water mudstones;(2) Saline to hypersaline mudstones;(3) Lacustrine dolomitic mudstones;(4) Lagoonal tufferous mudstones. The samples were analysed by GC and GC-MS to reveal the characteristic distributions of biological markers in their aliphatic fractions. The distribution of n-alkanes, isoprenoids, steranes and hopanoids as well as other biological marker compounds are discussed briefly. In terms of biological marker parameters of their aliphatic fractions, some immature to marginal mature oil samples sourced from hypersaline and saline mudstones are described. Immature or marginal mature crude oils occurred in shallow depth in Jianghan basin contain high amount of sulphur and organic sulphur compounds, especially abundant thiophene and thiolane homologues with remarkable even carbon number predominace.
1991, 9(S1): 21-25.
Abstract:
In this paper, distribution of the stable carbon isotope composition of individual n-alkanes. that analysed by GC/IRMS, was studied preliminary. There are five type of samples. Pj, Ps and PY expelled by thermal modelling; L extracted and L-HC1 released by hydrochloric acid from the carbonate rock(In Table 1). And the Authors explored the uses of GC/IRMS for correlation, migration, thermal history ana lysing and sedimentary environment of source rocks
In this paper, distribution of the stable carbon isotope composition of individual n-alkanes. that analysed by GC/IRMS, was studied preliminary. There are five type of samples. Pj, Ps and PY expelled by thermal modelling; L extracted and L-HC1 released by hydrochloric acid from the carbonate rock(In Table 1). And the Authors explored the uses of GC/IRMS for correlation, migration, thermal history ana lysing and sedimentary environment of source rocks
1991, 9(S1): 34-43.
Abstract:
The present paper investigated the extracts of mathanol-benzene soxhlet extraction for two extraordinary coals, namely, a Hunyuan algel candle in Shanxi Province and Lupinite in Jiangxi Province. by means of gas chromatography, and GC/MS techniquts. The chemical structures and configulation were identified by Kovats Values of gas chromatograms, mass chromatograms and the interpretation of mass fragmentagrams. The occurrence and distrbution feature of alkanes, isoprenoids, alkyl cycolhexanes, terpanes and steranes have been investigated. The correlalionship between some geochemical parameters and precursor of coal-original as well as sedimentary environment was discussed. Hunyuan algal candle is a sapropelic coal with higher H/C and O/ C atomic ratios(1.13 and 0.18 respectively) and there are many algae and waxes under the microscopic study. The conspicuously present of 17αH, 18αH, 21βH-28, 30-C28 bisnorhopane, gammacerane and γ-carotane have been firstly identi fied in this kind of boghead coal. Some geochemical parameters, such as pristane/phytane = 0.5, ∑ C20/ ∑C20+= 1. 04, C29-xxx-( R+ S)/C27- xxx-( R+ S) = 1. 66, index of gammacerane(gammacerane/ C30-xβhopane) =0.23, the ratio of 22S to 22R for C32-C35 hopane 1 and a few percentage of C15-C22 alkylcyclohexane as well as completely sterane system indicated that the paleoenvironment of Hunyuan algal candle was a reducing environment covered by saline water, the main input precursor is higher plant followed by algae and bacteria. Lupinite from Jinxi is an unique bark coal which is referred as Lupinite as new coal macerals in the petrography. In the alkane fraction of benzene- methanol extract from Lupinite, there are some geochemical characters as follows: a lack of sterane system is a quite special case in the coal extraction. n-C160is main component in the normal alkane, ∑C20-/ ∑ C20+= 3.2, Pr/Ph= 1.3, C12-C20 alkyl cyclohexane account 4%, the distribution of carbon number of alkyl cyclohexane as same as normal alkane, but the main peak is C15, one carbon number less than normal alkane. The ratio of 22S to 22R for C32-C35 hopane 1. The microscopic study indicated that Lupinite consists mainly of suberinite of Lepidodendrales and ferns as the primordial plant debris(account 50-70%) with decken structure due to paralic deposit environment in which both aerobic and anaerobic environment would be alternatively existed, therefore, both aerobic and anaerobic bacteria attacked the plant debris where completely decomposition of celluloses and lignin would be happened and only preserved stable exinite and suberinite as resi dues.
The present paper investigated the extracts of mathanol-benzene soxhlet extraction for two extraordinary coals, namely, a Hunyuan algel candle in Shanxi Province and Lupinite in Jiangxi Province. by means of gas chromatography, and GC/MS techniquts. The chemical structures and configulation were identified by Kovats Values of gas chromatograms, mass chromatograms and the interpretation of mass fragmentagrams. The occurrence and distrbution feature of alkanes, isoprenoids, alkyl cycolhexanes, terpanes and steranes have been investigated. The correlalionship between some geochemical parameters and precursor of coal-original as well as sedimentary environment was discussed. Hunyuan algal candle is a sapropelic coal with higher H/C and O/ C atomic ratios(1.13 and 0.18 respectively) and there are many algae and waxes under the microscopic study. The conspicuously present of 17αH, 18αH, 21βH-28, 30-C28 bisnorhopane, gammacerane and γ-carotane have been firstly identi fied in this kind of boghead coal. Some geochemical parameters, such as pristane/phytane = 0.5, ∑ C20/ ∑C20+= 1. 04, C29-xxx-( R+ S)/C27- xxx-( R+ S) = 1. 66, index of gammacerane(gammacerane/ C30-xβhopane) =0.23, the ratio of 22S to 22R for C32-C35 hopane 1 and a few percentage of C15-C22 alkylcyclohexane as well as completely sterane system indicated that the paleoenvironment of Hunyuan algal candle was a reducing environment covered by saline water, the main input precursor is higher plant followed by algae and bacteria. Lupinite from Jinxi is an unique bark coal which is referred as Lupinite as new coal macerals in the petrography. In the alkane fraction of benzene- methanol extract from Lupinite, there are some geochemical characters as follows: a lack of sterane system is a quite special case in the coal extraction. n-C160is main component in the normal alkane, ∑C20-/ ∑ C20+= 3.2, Pr/Ph= 1.3, C12-C20 alkyl cyclohexane account 4%, the distribution of carbon number of alkyl cyclohexane as same as normal alkane, but the main peak is C15, one carbon number less than normal alkane. The ratio of 22S to 22R for C32-C35 hopane 1. The microscopic study indicated that Lupinite consists mainly of suberinite of Lepidodendrales and ferns as the primordial plant debris(account 50-70%) with decken structure due to paralic deposit environment in which both aerobic and anaerobic environment would be alternatively existed, therefore, both aerobic and anaerobic bacteria attacked the plant debris where completely decomposition of celluloses and lignin would be happened and only preserved stable exinite and suberinite as resi dues.
1991, 9(S1): 52-58.
Abstract:
In this paper, the distribution of biomarkers in crude oils, tar sand bitumen and source rocks were studied and applied for oil/oil, oil/source correlation and biodegradation in Biyang Basin, China. Four oil samples(oil 1-4) collected from Biyang Basin were divided into two types: Type Ⅰ(oil 1-3) and Type Ⅱ(oil 4). Type I oil has lower values for ratios of Pr/Ph and 4-methylsterane/sterane, and higher values for ratio of sterane/hopane and gammacerane index than type Ⅱ oil. By oil/source correlation, it was believed that the source rocks with lower Pr/ Ph ratio and higher gammacerane index from Eh, formation had more contribution to the oil accumulation in Biyang Basin than other source rocks. Tar sand bitumen colllected from northern slope were biodegraded. Corrected Gammacerane Index, i, e. gammacerane /(C29-25-norhopane+C30-hopane)×100, of tar Sand bitumen wrer compared with that of regular crude oils. The quite close values indicate that tar sand bitumen have same source as type Ⅰ oils.
In this paper, the distribution of biomarkers in crude oils, tar sand bitumen and source rocks were studied and applied for oil/oil, oil/source correlation and biodegradation in Biyang Basin, China. Four oil samples(oil 1-4) collected from Biyang Basin were divided into two types: Type Ⅰ(oil 1-3) and Type Ⅱ(oil 4). Type I oil has lower values for ratios of Pr/Ph and 4-methylsterane/sterane, and higher values for ratio of sterane/hopane and gammacerane index than type Ⅱ oil. By oil/source correlation, it was believed that the source rocks with lower Pr/ Ph ratio and higher gammacerane index from Eh, formation had more contribution to the oil accumulation in Biyang Basin than other source rocks. Tar sand bitumen colllected from northern slope were biodegraded. Corrected Gammacerane Index, i, e. gammacerane /(C29-25-norhopane+C30-hopane)×100, of tar Sand bitumen wrer compared with that of regular crude oils. The quite close values indicate that tar sand bitumen have same source as type Ⅰ oils.
1991, 9(S1): 67-74.
Abstract:
The western depression of Liaohe Basin is one of the most prolific heavy oil-generating area in China. The analysis has shown that there are many kinds of heavy oils with different composition depending upon the degree of degradation. The present paper distinguishes the main types of heavy oils of the western depression and conducts correlation of differrent types of heavy oils by pyrolysis of purified asphaltenes. The results show that the heavy oils from the western slope of the western depression of Liaohe Oilfield are generated from the same source but subjected to different degrees of degradation(mainly biodegradation).The pyrolysis of a S4 kerogen has shown the S4 formation may be one of the source rock for these heavy oils.
The western depression of Liaohe Basin is one of the most prolific heavy oil-generating area in China. The analysis has shown that there are many kinds of heavy oils with different composition depending upon the degree of degradation. The present paper distinguishes the main types of heavy oils of the western depression and conducts correlation of differrent types of heavy oils by pyrolysis of purified asphaltenes. The results show that the heavy oils from the western slope of the western depression of Liaohe Oilfield are generated from the same source but subjected to different degrees of degradation(mainly biodegradation).The pyrolysis of a S4 kerogen has shown the S4 formation may be one of the source rock for these heavy oils.
1991, 9(S1): 83-89.
Abstract:
After oxidation of river and marine sediments with mild oxidizing reagents under alkaline conditions, the phenolic compounds in the oxidation products were determined gas chromatographicly and compared with that of lignin oxidation products. The appearance and relative distribution of lignin phenols in sediments were attributed to the influence of terrigenous organic materials. The alkaline CuO oxidation was compared with the alkaline nitrobenzene and the gas chromatographic determination of resulted phenols was tested. The results indicated that CuO is preferable to nitrobenzene as the oxidizing reagent at least for sediment samples and the silylation of resulted phenolic derivatives is essential to gas chromatographic determination with nonpolar capillary column. Clear separation and quantitaive determination of silylated derivatives are realized with only SE-30 capillary column. Sediments from Jiulongjiang River-Estuary-Xiamen Bay have been analized by the settled procedure. Lignin has been found in all the sediments taken from this area with similar oxidation products, suggesting an effect of Jiulongjiang River input on whole the area and that the terrigenous organic matter carried by Jiulongjiang river water is the main source of lignin found in this area. The content of lignin in freshwater- end sediments is higher than that in seawater- end sediments, indicating the effect of freshwater-seawater interaction on the distribution of lignin in this area.
After oxidation of river and marine sediments with mild oxidizing reagents under alkaline conditions, the phenolic compounds in the oxidation products were determined gas chromatographicly and compared with that of lignin oxidation products. The appearance and relative distribution of lignin phenols in sediments were attributed to the influence of terrigenous organic materials. The alkaline CuO oxidation was compared with the alkaline nitrobenzene and the gas chromatographic determination of resulted phenols was tested. The results indicated that CuO is preferable to nitrobenzene as the oxidizing reagent at least for sediment samples and the silylation of resulted phenolic derivatives is essential to gas chromatographic determination with nonpolar capillary column. Clear separation and quantitaive determination of silylated derivatives are realized with only SE-30 capillary column. Sediments from Jiulongjiang River-Estuary-Xiamen Bay have been analized by the settled procedure. Lignin has been found in all the sediments taken from this area with similar oxidation products, suggesting an effect of Jiulongjiang River input on whole the area and that the terrigenous organic matter carried by Jiulongjiang river water is the main source of lignin found in this area. The content of lignin in freshwater- end sediments is higher than that in seawater- end sediments, indicating the effect of freshwater-seawater interaction on the distribution of lignin in this area.
1991, 9(S1): 97-102.
Abstract:
The distribution of stenols and stanols were examined in leg 4-60-65(0-465cm)of marine sediment core from Beibuwan gulf of South China sea.Ten sterols named as Cholest-5-en-3β-o1; 5x-Cholest-3β-ol; 24-MethylchoIest-5, 22-di-en-3β-ol; 24-Methyl-5x-cholest-22-en-3β-ol; 24-Methylene cholest-5-en-3β-ol: 24-Methyl-5x-cholest-3β-ol; 23, 24-di-methy-lcholest-5, 22-di-en-3β-ol; 23, 24-Dimethyl-5x-cholest-22-en-3β-ol; 24-Ethylcholest-5-en-3β-ol; 24-Ethyl-5α-cholest-3β-ol have been identified by means of gas chromatography-mass spectromatry-data system. A high concentration of C27 sterols were mainly originated from zooplankton lipids. the C28 sterols were derived from diatom, the C27-C29 sterols were observed in various species of green and red algae, the C29 24-Ethylcholest-5-en-3β-ol as a biomarker is thought to indicate input of terrigeous organic matter, the C27-C29 sterols as a ecological indicator to recognize the source of organic matter in marine. These sterols are mainly come from zooplankton in marine environment. The results show that the C27 C28 and C29 5x-stanol/△5 stenol ratio increase with sediment depth, that means the evolution of sterols occur in the reducing environment of deeper marine sediments from Beibuwan gulf of South China Sea.
The distribution of stenols and stanols were examined in leg 4-60-65(0-465cm)of marine sediment core from Beibuwan gulf of South China sea.Ten sterols named as Cholest-5-en-3β-o1; 5x-Cholest-3β-ol; 24-MethylchoIest-5, 22-di-en-3β-ol; 24-Methyl-5x-cholest-22-en-3β-ol; 24-Methylene cholest-5-en-3β-ol: 24-Methyl-5x-cholest-3β-ol; 23, 24-di-methy-lcholest-5, 22-di-en-3β-ol; 23, 24-Dimethyl-5x-cholest-22-en-3β-ol; 24-Ethylcholest-5-en-3β-ol; 24-Ethyl-5α-cholest-3β-ol have been identified by means of gas chromatography-mass spectromatry-data system. A high concentration of C27 sterols were mainly originated from zooplankton lipids. the C28 sterols were derived from diatom, the C27-C29 sterols were observed in various species of green and red algae, the C29 24-Ethylcholest-5-en-3β-ol as a biomarker is thought to indicate input of terrigeous organic matter, the C27-C29 sterols as a ecological indicator to recognize the source of organic matter in marine. These sterols are mainly come from zooplankton in marine environment. The results show that the C27 C28 and C29 5x-stanol/△5 stenol ratio increase with sediment depth, that means the evolution of sterols occur in the reducing environment of deeper marine sediments from Beibuwan gulf of South China Sea.
1991, 9(S1): 112-119.
Abstract:
The content of organic matter enclosed in carbonate minerals is more abundant than that of extractable organic matter in many carbonate source rock. The maturity of enclosed organic matter is lower generally. Enclosed organic matter contains more abundant asphaltene and non- hydrocarbon compounds than extractable organic matter. Most of enclosed organic matter exist in the rings of calcite and dolomite. These rings is due to secondary growth in a certain stage of diagenesis. During the diagenesis, the soluble organic matter is produced step by step, in the same time, carbonate minerls secondarily grow or recrystallize and enclose soluble organic matter. The results of simulating experiments under high temperature and pressure show that this kind of organic mat'er nclosed in carbonate minerals can be released and converted into hydrocarbons. It is an effective oil-forming material. In addition to the difference of mineral catalytic power, the existence of enclosed organic matter is one of the reasons that the maturing speed of carbonate organic matter is lower than that of shale organic matter. In supermature stage of carbonate rocks(R01.3%), soluble organic matter, separating out from enclosed organic matter, makes bitumen A' s maturity lower. In the Lower Paleozoic carbonate rocks of TArim Basin, maturity of bitumen A is lower than solid asphalt' s. The 20S/(20R+20S) ratio of C29 sterane in bitumen A is 0.43 and 22S/((22S+22R) ratio of C3117α(H), 21β(H) hopane is 0.43. Both of them are lower than their equilibrium values. The solid asphalt reflectance in these carbonate rocks is equal to the vitrnite reflectance of 1.3%. As results of separating of enclosed organic matter, crystal hole oil seeps are widespread in the supermature carbonate rocks. In supermature stage, enclosed organic matter still can be coverted into liquid hydrocarbons. This is another oil- forming mechanism different from the oil- forming mechanism of kerogen. It may be of far reaching importance to recognize this kind of oil-froming mechanizm because huge thick-bedded carbonate rocks exist in the deep of the Tarim Basin.
The content of organic matter enclosed in carbonate minerals is more abundant than that of extractable organic matter in many carbonate source rock. The maturity of enclosed organic matter is lower generally. Enclosed organic matter contains more abundant asphaltene and non- hydrocarbon compounds than extractable organic matter. Most of enclosed organic matter exist in the rings of calcite and dolomite. These rings is due to secondary growth in a certain stage of diagenesis. During the diagenesis, the soluble organic matter is produced step by step, in the same time, carbonate minerls secondarily grow or recrystallize and enclose soluble organic matter. The results of simulating experiments under high temperature and pressure show that this kind of organic mat'er nclosed in carbonate minerals can be released and converted into hydrocarbons. It is an effective oil-forming material. In addition to the difference of mineral catalytic power, the existence of enclosed organic matter is one of the reasons that the maturing speed of carbonate organic matter is lower than that of shale organic matter. In supermature stage of carbonate rocks(R01.3%), soluble organic matter, separating out from enclosed organic matter, makes bitumen A' s maturity lower. In the Lower Paleozoic carbonate rocks of TArim Basin, maturity of bitumen A is lower than solid asphalt' s. The 20S/(20R+20S) ratio of C29 sterane in bitumen A is 0.43 and 22S/((22S+22R) ratio of C3117α(H), 21β(H) hopane is 0.43. Both of them are lower than their equilibrium values. The solid asphalt reflectance in these carbonate rocks is equal to the vitrnite reflectance of 1.3%. As results of separating of enclosed organic matter, crystal hole oil seeps are widespread in the supermature carbonate rocks. In supermature stage, enclosed organic matter still can be coverted into liquid hydrocarbons. This is another oil- forming mechanism different from the oil- forming mechanism of kerogen. It may be of far reaching importance to recognize this kind of oil-froming mechanizm because huge thick-bedded carbonate rocks exist in the deep of the Tarim Basin.
1991, 9(S1): 125-130.
Abstract:
Since conducting thorought oil exploration in the Pearl River Mouth Basin( PRMB) advanced achievement on the study of local geology and geochemistry has been gained. It has been proven that the oil formation and accumulation in the PRMB is characterized by "terrestrial-originated while marine-reser-voired". That is, both terrestrially lacustrine Wenchang mudstone and coaly Enping Formation are the main sources of the oil whilst the overlying marine sandstone and mudstone of Zhuhai and Zhujiang formations contribute reservoir beds and caprocks. Such a good combination of source rock, reservoir bed and caprock enables the oil exploration in the PRMB successfully. However, with upgrading the exploration degree more and more data suggests that the marine mudstone occurred in both Zhuhai and Zhujiang Formations can not only be as the caprock but also be as subordinary source of the oil when buried at a certain depth because it possesses a certain organic abundance. But there has not yet been any proof for one to confirm that the marine mudstone has ever provided oil for the PRMB. To find the evidence, geochemical features of two lowmature crude oils and one respective Zhuhai and Zhujiang mudstone were studuied in detail. Results showed that both Zhuhai and Zhujiang mudstones were organic-riched, and while buried at the depth below 2500 meters the Zhuhai source rock became marginally mature Moreover, geochemical analyses for saturated and aromatic fractions indicated that benzohopanes, the biomarker indicator of lower thermal maturity, were ubiquatous in both the crudes and the extracts, whereas C30 4-methyl steranes were common compounds in the oils but not in the extracts, thus suggesting that the low maturity of the oils should be attributed to the mix up of the oil with lower maturation level, of which the would-be source rock was Zhuhai mudstone owing to the absence of benzohopanes in the terrestrial source rocks. The finding was of great importance because Zhuhai Formation is widespread, especially in Baiyun Depression, in which the formation was buried at the depth around 3000 meters according to seismic section and therefore just entered the OGM. hence was probably an important oil source.
Since conducting thorought oil exploration in the Pearl River Mouth Basin( PRMB) advanced achievement on the study of local geology and geochemistry has been gained. It has been proven that the oil formation and accumulation in the PRMB is characterized by "terrestrial-originated while marine-reser-voired". That is, both terrestrially lacustrine Wenchang mudstone and coaly Enping Formation are the main sources of the oil whilst the overlying marine sandstone and mudstone of Zhuhai and Zhujiang formations contribute reservoir beds and caprocks. Such a good combination of source rock, reservoir bed and caprock enables the oil exploration in the PRMB successfully. However, with upgrading the exploration degree more and more data suggests that the marine mudstone occurred in both Zhuhai and Zhujiang Formations can not only be as the caprock but also be as subordinary source of the oil when buried at a certain depth because it possesses a certain organic abundance. But there has not yet been any proof for one to confirm that the marine mudstone has ever provided oil for the PRMB. To find the evidence, geochemical features of two lowmature crude oils and one respective Zhuhai and Zhujiang mudstone were studuied in detail. Results showed that both Zhuhai and Zhujiang mudstones were organic-riched, and while buried at the depth below 2500 meters the Zhuhai source rock became marginally mature Moreover, geochemical analyses for saturated and aromatic fractions indicated that benzohopanes, the biomarker indicator of lower thermal maturity, were ubiquatous in both the crudes and the extracts, whereas C30 4-methyl steranes were common compounds in the oils but not in the extracts, thus suggesting that the low maturity of the oils should be attributed to the mix up of the oil with lower maturation level, of which the would-be source rock was Zhuhai mudstone owing to the absence of benzohopanes in the terrestrial source rocks. The finding was of great importance because Zhuhai Formation is widespread, especially in Baiyun Depression, in which the formation was buried at the depth around 3000 meters according to seismic section and therefore just entered the OGM. hence was probably an important oil source.
1991, 9(S1): 138-146.
Abstract:
Whether bitumen reflectance can be used as a reliable mature parameter of source rocks is an unsolved problem for a long time. In this paper, the detailed geological characteristics and optical properties of bitumen occurring in source rocks are investigated with the organic petrological methods. Combining the results of thermal simulating tests of bitumen, the authors obtain the following acknowdges: 1. Bitumen belongs to a maceral group in the classification system of dispersed organic matter in sedimentary rocks. Bitumen occurring in source rocks may be divided into three macerals accouding to its origin: autobitumen, allobitumen and reworked bitumen. Forthermore, autobitumen is subdivided into three submacerals: pre-oil-bitjimen, post-oil-bitumen and oxidized bitumen on the basis of their forming pattern, and allobitumen into two submaceralss: early allobitumen and late allobitumen accouding to the relative maturation of the source rocks into which the bitumes pour. 2. Autobitumen is the most abundant bitumen in all types of source rocks, and it is characterized by a secounday form, and fills into the microfissures or microholes in source rocks. The distribution of allobitumen depends on the regional geological background to great extent. It appears often in the basins in which there are more than one oil source rocks seams with different geological time. The fundamental difference between autobitumen and allobitumen is in that the reflectance of allobitumen is unfit with the maturation level of the source rock in which it occurs. Reworked bitumen usually occurs in clay source rocks, and is characterized by original deposited occurrence and paralleling with stratification of the source rock. 3. That the significance of bitumen reflectance are used as a parameter depends upon, on one hand, its origin types and regional geological background, on the other hand, the maturation level of the source rocks and its optical structure. In most cases, the reflectance of autobitumes can be only used as a mature parameter. However, in some cases, the reflectance of the allobitumen in continous deposition basin and the reworked bitumen in very high mature stage source rocks can be also used to determine its source rocks maturation level. The reflectance of autobitumen has a good relation with the vitrinite reflectance or mature stage within the region of high mature stage to dry gas stage(about vitrinite reflectance from 0.01 to 2.0%), and is an excellent mature parameter, but, the reflectance of bitumen can be only used as a reference mature parameter when the mature level of source rocks is too high or two low,
Whether bitumen reflectance can be used as a reliable mature parameter of source rocks is an unsolved problem for a long time. In this paper, the detailed geological characteristics and optical properties of bitumen occurring in source rocks are investigated with the organic petrological methods. Combining the results of thermal simulating tests of bitumen, the authors obtain the following acknowdges: 1. Bitumen belongs to a maceral group in the classification system of dispersed organic matter in sedimentary rocks. Bitumen occurring in source rocks may be divided into three macerals accouding to its origin: autobitumen, allobitumen and reworked bitumen. Forthermore, autobitumen is subdivided into three submacerals: pre-oil-bitjimen, post-oil-bitumen and oxidized bitumen on the basis of their forming pattern, and allobitumen into two submaceralss: early allobitumen and late allobitumen accouding to the relative maturation of the source rocks into which the bitumes pour. 2. Autobitumen is the most abundant bitumen in all types of source rocks, and it is characterized by a secounday form, and fills into the microfissures or microholes in source rocks. The distribution of allobitumen depends on the regional geological background to great extent. It appears often in the basins in which there are more than one oil source rocks seams with different geological time. The fundamental difference between autobitumen and allobitumen is in that the reflectance of allobitumen is unfit with the maturation level of the source rock in which it occurs. Reworked bitumen usually occurs in clay source rocks, and is characterized by original deposited occurrence and paralleling with stratification of the source rock. 3. That the significance of bitumen reflectance are used as a parameter depends upon, on one hand, its origin types and regional geological background, on the other hand, the maturation level of the source rocks and its optical structure. In most cases, the reflectance of autobitumes can be only used as a mature parameter. However, in some cases, the reflectance of the allobitumen in continous deposition basin and the reworked bitumen in very high mature stage source rocks can be also used to determine its source rocks maturation level. The reflectance of autobitumen has a good relation with the vitrinite reflectance or mature stage within the region of high mature stage to dry gas stage(about vitrinite reflectance from 0.01 to 2.0%), and is an excellent mature parameter, but, the reflectance of bitumen can be only used as a reference mature parameter when the mature level of source rocks is too high or two low,
1991, 9(S1): 152-162.
Abstract:
The chemical structure of Yunan sphugnum brown coal and its solid state thermo-simulated products atvanous temperatures were investigated by the newest developed solid state high resdution NMR techniques(i.e，1H CRAMPS Spectrum, 1H spin-Lattice relaxation time T1and 1H homo-nuclear Bipolar dephasingdecay constant Too, 13C CPMAS spectrum, 13C spin-lattice relaxation time T1and,13C hetero-nucleardepolar dephasing decay constant TDDThe results clearly reveal the mechanism of generation and expul-sion of gaseous and liquid hydrocarbons during the thermo-simulating process of Yunan sphugnum Brown coal
The chemical structure of Yunan sphugnum brown coal and its solid state thermo-simulated products atvanous temperatures were investigated by the newest developed solid state high resdution NMR techniques(i.e，1H CRAMPS Spectrum, 1H spin-Lattice relaxation time T1and 1H homo-nuclear Bipolar dephasingdecay constant Too, 13C CPMAS spectrum, 13C spin-lattice relaxation time T1and,13C hetero-nucleardepolar dephasing decay constant TDDThe results clearly reveal the mechanism of generation and expul-sion of gaseous and liquid hydrocarbons during the thermo-simulating process of Yunan sphugnum Brown coal
1991, 9(S1): 171-177.
Abstract:
Both laboratory and field studies show that organic matter could play an important role in the forming of sediment-reformed deposits. 1.Forming sediment source rock Humic and fulvic acids have a strong tendency to complex and to absorb metal elements, one gram fulvic acid can complex and absorb 188mg Cu, 165mg Zn, and 276mg Cd respectively; one gram sea algal fregment can combine 58-78μg Au. Humic and fulvic acids are high molecular- weight, weak acid polyelectrolyts, and they are coagulated by strong electrolyte(sea water); biodetritus and clay mineral usually get to setttl in sea water and fresh water. Then humic matter and metal elements carried by it would be able to deposit and to form source rock. 2.The role in mobilization and migration of metal elements The determining results show that interlayer water and oil-field water were rich in organic acids and cyclic compounds containing O, S, P, N, etc.; while their character is simillar with ore-forming solution(called low temperature ore-forming solutions). The experimental studies suggest:(1) The solubility of mineral(sphalerite and galena) is much higher in solutions containing dissolved organic compounds than in inorganic solutions(generally 4-17 times);(2) the four complexes studied, lactic acid-Zn complex, EDTA-Zn and fulvic acid-Zn have high thermal stability, their thermal decomposition temperatures are in the rang of 140-240℃. 3.The migration and accumulation of metal elements in crud oil(waterree system) Experimental results suggest that crude oil has a strong tendency of extracting metal elements from aquous solutions, 54-90% of Au, Cu, Pb, Zn can be extracted solubility of mineral in mineral-crude oil-solution system is much higher than that of single aquous solution. The authors suggest that some mud-rock and shale had ever ben "double source rock", metal elements were mobilized. When petroleum was formed and migrated.
Both laboratory and field studies show that organic matter could play an important role in the forming of sediment-reformed deposits. 1.Forming sediment source rock Humic and fulvic acids have a strong tendency to complex and to absorb metal elements, one gram fulvic acid can complex and absorb 188mg Cu, 165mg Zn, and 276mg Cd respectively; one gram sea algal fregment can combine 58-78μg Au. Humic and fulvic acids are high molecular- weight, weak acid polyelectrolyts, and they are coagulated by strong electrolyte(sea water); biodetritus and clay mineral usually get to setttl in sea water and fresh water. Then humic matter and metal elements carried by it would be able to deposit and to form source rock. 2.The role in mobilization and migration of metal elements The determining results show that interlayer water and oil-field water were rich in organic acids and cyclic compounds containing O, S, P, N, etc.; while their character is simillar with ore-forming solution(called low temperature ore-forming solutions). The experimental studies suggest:(1) The solubility of mineral(sphalerite and galena) is much higher in solutions containing dissolved organic compounds than in inorganic solutions(generally 4-17 times);(2) the four complexes studied, lactic acid-Zn complex, EDTA-Zn and fulvic acid-Zn have high thermal stability, their thermal decomposition temperatures are in the rang of 140-240℃. 3.The migration and accumulation of metal elements in crud oil(waterree system) Experimental results suggest that crude oil has a strong tendency of extracting metal elements from aquous solutions, 54-90% of Au, Cu, Pb, Zn can be extracted solubility of mineral in mineral-crude oil-solution system is much higher than that of single aquous solution. The authors suggest that some mud-rock and shale had ever ben "double source rock", metal elements were mobilized. When petroleum was formed and migrated.
1991, 9(S1): 187-196.
Abstract:
The sovent-extractable organic matter(lipids) of eight airborne dust samples at different heights,which were collected at the meteorological tower of Beijing, in the city of Shuicheng and on the outskirts ofGuangzhou, using a standard volume air sample, were investigated to determine the distributions ofhomologous com pounds and molecular markers. All of collected sample filters were ultrasonically extractedin organic solvents. The extracts were esterified and then separated by TLC. Compound molecular structureof the fractions were characterized by GC-MS. These preliminary results show that all samples containn-alkanes. n-fatty acids, steranes, triterpanes. PAH and so on. derived from both biogenic sources(vascular plant wax and microbial lipids input) and fossil fuel contamination(coal. crude oil, etc.).Some apparent fractionatinon phenomena of lipids in dusts were observed in samlpes from different heightsabove ground. The upper is the height of dusts, the less is the lipid yield of particles. PAH compounds aremainly present in fine mode particles. The concentrations of P,AH，triterpane and sterane will decrease asthe sampling height incensing. Dusts in the upper atmosphere has significantly lower concentrations ofanthropogenic and microbial components. The analytical results also indicate that upper airborne dust trans-port over longer distances.
The sovent-extractable organic matter(lipids) of eight airborne dust samples at different heights,which were collected at the meteorological tower of Beijing, in the city of Shuicheng and on the outskirts ofGuangzhou, using a standard volume air sample, were investigated to determine the distributions ofhomologous com pounds and molecular markers. All of collected sample filters were ultrasonically extractedin organic solvents. The extracts were esterified and then separated by TLC. Compound molecular structureof the fractions were characterized by GC-MS. These preliminary results show that all samples containn-alkanes. n-fatty acids, steranes, triterpanes. PAH and so on. derived from both biogenic sources(vascular plant wax and microbial lipids input) and fossil fuel contamination(coal. crude oil, etc.).Some apparent fractionatinon phenomena of lipids in dusts were observed in samlpes from different heightsabove ground. The upper is the height of dusts, the less is the lipid yield of particles. PAH compounds aremainly present in fine mode particles. The concentrations of P,AH，triterpane and sterane will decrease asthe sampling height incensing. Dusts in the upper atmosphere has significantly lower concentrations ofanthropogenic and microbial components. The analytical results also indicate that upper airborne dust trans-port over longer distances.
1991, 9(S1): 9-20.
Abstract:
The polycyclic aromatic hydrocarbons of the Tertiary brown coal from Zhoujing Mine have been characterized in detail. They are composed mainly of aromatic sesqui-, di-, sester- and triterpenoid hydrocarbons, with retene and simonellite as the predominant species. Secondary in abundance are mono-to penta-aromatic triterpenoid hydrocarbons, derived from oleanane, ursane and lupane precursors, indicators of terrestrial sources. Minor species present are a tetra-aromatic norhopane, undecyltoluene and perylene, and most of the regular PAH are found at trace levels only.
The polycyclic aromatic hydrocarbons of the Tertiary brown coal from Zhoujing Mine have been characterized in detail. They are composed mainly of aromatic sesqui-, di-, sester- and triterpenoid hydrocarbons, with retene and simonellite as the predominant species. Secondary in abundance are mono-to penta-aromatic triterpenoid hydrocarbons, derived from oleanane, ursane and lupane precursors, indicators of terrestrial sources. Minor species present are a tetra-aromatic norhopane, undecyltoluene and perylene, and most of the regular PAH are found at trace levels only.
1991, 9(S1): 26-33.
Abstract:
Biomarkers of Pleistocene peats, clays from Caohai basin of Guizhou Province and Pliocene lignites from Shuijingwan of Yunnan Province were analysed by GC and GC-MS. As a result, a series of hopenes. ββ-hopanes and large amount of C31-xβ-22R homohopane were found. In addition, De-A-Lupanes, De-A-Lupenes, fichtelites, norpimaranes, sandacopimaranes, abitane and its isomers were also confirmed in the samples. It is proposed that C31-xβ-22R homohopane may mainly originated from high plants, while C32 hopanes and their higher homolog from bacteria and other prokaryotic organism. As fichtelite is much related to coal and woody peats, it may be employed as an indicator of higher plant imput. During early diagenesis stage, the evolution pathway of hopanoids may as follows: hopenes transformed to xβ-hopanes, then ββ-hopanes to αβ-hopanes and C31-αβ-22R hopane to C29. C30-xβ-hopanes etc.
Biomarkers of Pleistocene peats, clays from Caohai basin of Guizhou Province and Pliocene lignites from Shuijingwan of Yunnan Province were analysed by GC and GC-MS. As a result, a series of hopenes. ββ-hopanes and large amount of C31-xβ-22R homohopane were found. In addition, De-A-Lupanes, De-A-Lupenes, fichtelites, norpimaranes, sandacopimaranes, abitane and its isomers were also confirmed in the samples. It is proposed that C31-xβ-22R homohopane may mainly originated from high plants, while C32 hopanes and their higher homolog from bacteria and other prokaryotic organism. As fichtelite is much related to coal and woody peats, it may be employed as an indicator of higher plant imput. During early diagenesis stage, the evolution pathway of hopanoids may as follows: hopenes transformed to xβ-hopanes, then ββ-hopanes to αβ-hopanes and C31-αβ-22R hopane to C29. C30-xβ-hopanes etc.
1991, 9(S1): 44-51.
Abstract:
Cambrian and Odovician marine sediments are widespread in the Keping and Kylyketake regions of the Tarim Basin. The destribution of aliphatic biomarkers of 22 samples indicate that salified lagoon sediments, freshened lagoon sediments, shallow shelf and lower slope-shelf sediments, gravity flow sediments of shallow sea slope, deep water shelf sediments and sea floor basin sediments are different in the distribution of biomarkers. The differences between salified and freshened lagoon sediments in the distribution of biomarkers reflect the difference of palaeoclimate and biological input. The formers Pr/Ph ratios 1, contents of gammacerane are 0.28-0.34. and mor abundant β- carotane, while the laters 1, 0.07-0.12, containing pregnane and no β-carotane, respectively. Shallow shelf and lower slope-shelf sediments have the Pr/Ph ratios of 0.76-1.12 and no β-carotane. and are characterized by lower carbon number n-alkanes with odd carbon predominance or even carbon predominance, the contents of hopane sieries are very lower and demethylated hopanes are present abundantly in the triterpanes. The gravity flow sediments of shallow sea slope contain β-carotane, pregnane. lower carbon number n-alkanes with odd carbon predominance or even carbon predominance and alkyl cyclohexanes with even carbon predominance. Gammacerane contents of deep water shelf sediments are 0.04-0.18. Pr/Ph ratios are 1.00-1.82, pregnane is more abundant, cholestane/ethylcholestane ratios are 1.22-1.38. Sea floor basin sediments are characterized by the Pr/Ph ratios of 0.50-0.75, β-carotane contents are more abundant, gammacerane contents are 0.18-0.27, tricyclic terpanes contents are lower, alkyl cyclohexanes have even preference. Gammacerane contents are related to salinity. The Pr/Ph ratio and c-carotane content reflect the reduction degree of sedimentary environments. Pr/Ph 1 and more abundant β-carotane content indicate strongly reducing sedimentary environment.The Pr/Ph ratios are also influenced by the zooplankton input. Lower carbon number alkanes with odd over even preference or even over odd preference, alkyl cyclonhexanes with even over odd prefrence, tricyclic terpane distribution and sterane distribution are very important for the assessment of palaeoenvironments of Lower Palaeozoic sediments. Tricyclic terpane contents are lower and the(C20+C21) /(C23+ C24) ratios of tricyclic terpanes are 1 in salified lagoon vedinents, the gravity flow sediments of shallow sea slope and sea floor basin sediments. Tricyclic terpane contents are higher and the(C20+C21)(C23+C24) ratios are 1 in freshened sediments and deep water shelf sediments.
Cambrian and Odovician marine sediments are widespread in the Keping and Kylyketake regions of the Tarim Basin. The destribution of aliphatic biomarkers of 22 samples indicate that salified lagoon sediments, freshened lagoon sediments, shallow shelf and lower slope-shelf sediments, gravity flow sediments of shallow sea slope, deep water shelf sediments and sea floor basin sediments are different in the distribution of biomarkers. The differences between salified and freshened lagoon sediments in the distribution of biomarkers reflect the difference of palaeoclimate and biological input. The formers Pr/Ph ratios 1, contents of gammacerane are 0.28-0.34. and mor abundant β- carotane, while the laters 1, 0.07-0.12, containing pregnane and no β-carotane, respectively. Shallow shelf and lower slope-shelf sediments have the Pr/Ph ratios of 0.76-1.12 and no β-carotane. and are characterized by lower carbon number n-alkanes with odd carbon predominance or even carbon predominance, the contents of hopane sieries are very lower and demethylated hopanes are present abundantly in the triterpanes. The gravity flow sediments of shallow sea slope contain β-carotane, pregnane. lower carbon number n-alkanes with odd carbon predominance or even carbon predominance and alkyl cyclohexanes with even carbon predominance. Gammacerane contents of deep water shelf sediments are 0.04-0.18. Pr/Ph ratios are 1.00-1.82, pregnane is more abundant, cholestane/ethylcholestane ratios are 1.22-1.38. Sea floor basin sediments are characterized by the Pr/Ph ratios of 0.50-0.75, β-carotane contents are more abundant, gammacerane contents are 0.18-0.27, tricyclic terpanes contents are lower, alkyl cyclohexanes have even preference. Gammacerane contents are related to salinity. The Pr/Ph ratio and c-carotane content reflect the reduction degree of sedimentary environments. Pr/Ph 1 and more abundant β-carotane content indicate strongly reducing sedimentary environment.The Pr/Ph ratios are also influenced by the zooplankton input. Lower carbon number alkanes with odd over even preference or even over odd preference, alkyl cyclonhexanes with even over odd prefrence, tricyclic terpane distribution and sterane distribution are very important for the assessment of palaeoenvironments of Lower Palaeozoic sediments. Tricyclic terpane contents are lower and the(C20+C21) /(C23+ C24) ratios of tricyclic terpanes are 1 in salified lagoon vedinents, the gravity flow sediments of shallow sea slope and sea floor basin sediments. Tricyclic terpane contents are higher and the(C20+C21)(C23+C24) ratios are 1 in freshened sediments and deep water shelf sediments.
1991, 9(S1): 59-66.
Abstract:
It is well-known that β-(H) unsubstituted porphyrins present in sediments exclusively. Recently, several β-(H) unsubstituted porphyrins have been isolated by HPLC and identified by CI-MS and 'HNMR. However, many aspects of their characterisation remain unresolved. In the present papers, Friedel-Crafts acetylation, thin layer chromatography and Probe-MS are used for investigation of geoporphyrins in Lmk6. Ten red bands were obtained from TLC plate. The results show the methods could separated the porphyrin isomers roughly, and are able to reveal the characterisation of β-(H) unsubstituted porphyrins. For instance, A-4 series mainly occurs in β -(H) unsubstituted fraction and A-8 series only appears in fully alkylated fraction. Normally, β-(H) unsubstituted porphyrins are rich in the compounds of low carbon numbers. Results also show the TLC behaviour of Cu porphyrins. For fully alkylated porphyrins, Rf of A series that of A-2 and A-4 that of A-8. However, for β-(H) unsubstituted porphyrins. Rf ofAseries that of A-2 series.
It is well-known that β-(H) unsubstituted porphyrins present in sediments exclusively. Recently, several β-(H) unsubstituted porphyrins have been isolated by HPLC and identified by CI-MS and 'HNMR. However, many aspects of their characterisation remain unresolved. In the present papers, Friedel-Crafts acetylation, thin layer chromatography and Probe-MS are used for investigation of geoporphyrins in Lmk6. Ten red bands were obtained from TLC plate. The results show the methods could separated the porphyrin isomers roughly, and are able to reveal the characterisation of β-(H) unsubstituted porphyrins. For instance, A-4 series mainly occurs in β -(H) unsubstituted fraction and A-8 series only appears in fully alkylated fraction. Normally, β-(H) unsubstituted porphyrins are rich in the compounds of low carbon numbers. Results also show the TLC behaviour of Cu porphyrins. For fully alkylated porphyrins, Rf of A series that of A-2 and A-4 that of A-8. However, for β-(H) unsubstituted porphyrins. Rf ofAseries that of A-2 series.
1991, 9(S1): 75-82.
Abstract:
The geochemical characteristics of extracts from the crude oils and reservoir bed taken from a well drilled in Pearl River Mouth Basin(PRMB) were investigated in detail. The trap on which the well was drilled was cut by a sub-EW direction normal fault. And study of the seismic section passed the well revealed that the fault has ever had three main developments. Fractionation results indicated that both the crudes and the extracts were richer in saturates(63.34-73.03%) and poorer in polar fraction(non-hydrocarbon+asphaltene, 11.31-20.43%).And saturate to aromatic ratios being larger than 3(the maximum up to 6.21) suggested their higher rank of maturation level. GC patterns of the saturates showed that there are tow major types of crudes in the trap. One is minor biodegrated, which occurred in the upper section(2005m and its above), and the other was normal, which distributed in the lower section(below 2005m).Furthermore, because of the injection of the oil with much higher maturity and lower molecular weights the top two ranked the highest maturity of the biodegraded oils, thus their n- alkane carbon number distribution appeared saw- toothed shape. Therefore, the biodegraded oil can in turn be divided into two sub-types: mixed vs. non-mixed. GC/MS analyses for the saturates confirmed that the crudes have ever experiienced higher geotemperature due to the discovery of diadrimanes and 8. 14-secohopanes. And the presence of oleanane implied the terrestrial origin of the oils while the dominant C30 4-methyl steranes in the sterane kingdom revealed evriched algal organic input in the source rocks. The fault development survey revealed that the essential cause responsible for the varying geochemical features of the upper biodegraded oils was resulted from the reaccumulation of the oils in the trap. The development of the fault resulted in the escaping of the underlying highly mature crudes from their initial reservirs and immidiately migrating upward along the fault. They favorably entered the shalowest reservoirs owing to differential accumulation, resulting in the ever-biodegraded oils upgrated their maturity and enriched in lihter carbon isotope composition and lower molecular weight n- alkanes because of mixed with the reaccumulated hydrocarbons.
The geochemical characteristics of extracts from the crude oils and reservoir bed taken from a well drilled in Pearl River Mouth Basin(PRMB) were investigated in detail. The trap on which the well was drilled was cut by a sub-EW direction normal fault. And study of the seismic section passed the well revealed that the fault has ever had three main developments. Fractionation results indicated that both the crudes and the extracts were richer in saturates(63.34-73.03%) and poorer in polar fraction(non-hydrocarbon+asphaltene, 11.31-20.43%).And saturate to aromatic ratios being larger than 3(the maximum up to 6.21) suggested their higher rank of maturation level. GC patterns of the saturates showed that there are tow major types of crudes in the trap. One is minor biodegrated, which occurred in the upper section(2005m and its above), and the other was normal, which distributed in the lower section(below 2005m).Furthermore, because of the injection of the oil with much higher maturity and lower molecular weights the top two ranked the highest maturity of the biodegraded oils, thus their n- alkane carbon number distribution appeared saw- toothed shape. Therefore, the biodegraded oil can in turn be divided into two sub-types: mixed vs. non-mixed. GC/MS analyses for the saturates confirmed that the crudes have ever experiienced higher geotemperature due to the discovery of diadrimanes and 8. 14-secohopanes. And the presence of oleanane implied the terrestrial origin of the oils while the dominant C30 4-methyl steranes in the sterane kingdom revealed evriched algal organic input in the source rocks. The fault development survey revealed that the essential cause responsible for the varying geochemical features of the upper biodegraded oils was resulted from the reaccumulation of the oils in the trap. The development of the fault resulted in the escaping of the underlying highly mature crudes from their initial reservirs and immidiately migrating upward along the fault. They favorably entered the shalowest reservoirs owing to differential accumulation, resulting in the ever-biodegraded oils upgrated their maturity and enriched in lihter carbon isotope composition and lower molecular weight n- alkanes because of mixed with the reaccumulated hydrocarbons.
1991, 9(S1): 90-96.
Abstract:
Series of di-and triunsaturated ketones in marine surface sediments from South China Sea and Okinawa Trench are identified in varying amounts by thinlayer chromatography, gas chromatography and computerised gas chromatography-mass spectrometry.They are C37 3Me, C37 2Me.C38 3Et, C38 3Me, C38 2Et, C38 2Me. C39 3Et and C39 2Et respectively. Electron impact high resolution mass spectrometry of the appropriate TLC-fractions(Rf= 0.45-0.80) revealed that the alkenones have molecular ion peaks at m/e 528. 530, 542. 544. 556. and 558 and abundant peaks at m/z 55. 57.67. 71. 82. 96.etc in their mass spectra. The alkenone of C37 2Me is the most abundant component in the alkenones. The fact that the undetection of alkenones in the modern sediments from Antarctic suggests that the abundances of long- chain alkenones in sediments are related to the geographical distribution of some marin organisms such as ? huxleyi. The distribution of the alkenone relative abundances of the four samples is very similar which implies that alkenones appear to be restricted to a few species of the class Prymnesiophyceae. notably cocclithophorids of the family gephyrocapsaceae. The degree of unsaturation of alkenones decreases as growth temperature increases. The relation between unsaturation index U37k(=C37 2/[C37 2+C37 3]) calculated on the amounts of C37 2Me and sea surface temperature is as follows: U37K=0.034T+0.039 Sea surface temperatures estimated on Up are close to the values measured in the field. This suggests that long- chain alkenones cas be used as a geochemical tool to estimate not only past surface water temperatures but also environmental conditions of sediment deposition.
Series of di-and triunsaturated ketones in marine surface sediments from South China Sea and Okinawa Trench are identified in varying amounts by thinlayer chromatography, gas chromatography and computerised gas chromatography-mass spectrometry.They are C37 3Me, C37 2Me.C38 3Et, C38 3Me, C38 2Et, C38 2Me. C39 3Et and C39 2Et respectively. Electron impact high resolution mass spectrometry of the appropriate TLC-fractions(Rf= 0.45-0.80) revealed that the alkenones have molecular ion peaks at m/e 528. 530, 542. 544. 556. and 558 and abundant peaks at m/z 55. 57.67. 71. 82. 96.etc in their mass spectra. The alkenone of C37 2Me is the most abundant component in the alkenones. The fact that the undetection of alkenones in the modern sediments from Antarctic suggests that the abundances of long- chain alkenones in sediments are related to the geographical distribution of some marin organisms such as ? huxleyi. The distribution of the alkenone relative abundances of the four samples is very similar which implies that alkenones appear to be restricted to a few species of the class Prymnesiophyceae. notably cocclithophorids of the family gephyrocapsaceae. The degree of unsaturation of alkenones decreases as growth temperature increases. The relation between unsaturation index U37k(=C37 2/[C37 2+C37 3]) calculated on the amounts of C37 2Me and sea surface temperature is as follows: U37K=0.034T+0.039 Sea surface temperatures estimated on Up are close to the values measured in the field. This suggests that long- chain alkenones cas be used as a geochemical tool to estimate not only past surface water temperatures but also environmental conditions of sediment deposition.
1991, 9(S1): 103-111.
Abstract:
In this srudy, some representative samples of normal crude oils in Biyang basin and heavy oils of Northwestern slope of the basin, as well as the major possibly source rocks have been investigated by means of organic geochemical technigues. The main results are as follows: l.By conparison with normal crude oils occurred in Biyang basin, the heavy oils located in NW slope of the basin possess higher viscosity( 280 mPa. s), higher concentration of resins plus asphaltenes( 34%), lower wax( 15%)and lower condensation point( 24℃), besides they have bigger specificgracity. 2.Physical properties of heavy oils located in different part of the NW slope exist some differentiations. The colser to the NW margin of the basin, the bigger spesific gravity. With increasing spesific gravity of the sample, its viscosity and concentration of resins plus asphaltenes increased, while its wax decreased. Besides the common biomarkers, some special biodegredating products, such as(aaabbb)-25-norhopane, 17 β-28-norlupane, 17β-23, 28-bionorlupane and so on have been also deteceed in saturated hydrocarbon fractionations of heavy oils. 3.According to the input imformation, such as the ratios of steranes/terpanes, gammacerane/C30x β-hopane and maturity parameters, such as the ratios of motane/hopane, C29-sterane-ααα 20S/20(S+R) and C29-Sterane-ββ /(αα+ββ), the normal crude oils can be divided into three groups. The B86-B4062 group collected at the centre-southern part of the basin is much similar toheavy oils, as far as original molecuilar parameters is concerned. 4.The 3rd member of-fietaoyuan Formation(Eha) situated in NW slope of the basin is still immature source rock. So far it hasn't been entered into the oil generation threshold. Besides, the various biomarker parameters of it are different from that of heavy oils. Based on the comprehensive study of the characteristics mentioned above,the authors suggeste that the heavy oils of NW slope of Biyang depression originated from secondaryalteration(include oxidative degradation and biological degradation) pf the normal crudeoils, i.e both heavy oils of NW slope and normal crude oil of center-southern part of the basin have the same source. While the normal crude oil was migrated, accumulated and preserved in the shallow reservoirs of NW slope of the basin, it suffered secondary alteration and formed the heavy oil progressively.
In this srudy, some representative samples of normal crude oils in Biyang basin and heavy oils of Northwestern slope of the basin, as well as the major possibly source rocks have been investigated by means of organic geochemical technigues. The main results are as follows: l.By conparison with normal crude oils occurred in Biyang basin, the heavy oils located in NW slope of the basin possess higher viscosity( 280 mPa. s), higher concentration of resins plus asphaltenes( 34%), lower wax( 15%)and lower condensation point( 24℃), besides they have bigger specificgracity. 2.Physical properties of heavy oils located in different part of the NW slope exist some differentiations. The colser to the NW margin of the basin, the bigger spesific gravity. With increasing spesific gravity of the sample, its viscosity and concentration of resins plus asphaltenes increased, while its wax decreased. Besides the common biomarkers, some special biodegredating products, such as(aaabbb)-25-norhopane, 17 β-28-norlupane, 17β-23, 28-bionorlupane and so on have been also deteceed in saturated hydrocarbon fractionations of heavy oils. 3.According to the input imformation, such as the ratios of steranes/terpanes, gammacerane/C30x β-hopane and maturity parameters, such as the ratios of motane/hopane, C29-sterane-ααα 20S/20(S+R) and C29-Sterane-ββ /(αα+ββ), the normal crude oils can be divided into three groups. The B86-B4062 group collected at the centre-southern part of the basin is much similar toheavy oils, as far as original molecuilar parameters is concerned. 4.The 3rd member of-fietaoyuan Formation(Eha) situated in NW slope of the basin is still immature source rock. So far it hasn't been entered into the oil generation threshold. Besides, the various biomarker parameters of it are different from that of heavy oils. Based on the comprehensive study of the characteristics mentioned above,the authors suggeste that the heavy oils of NW slope of Biyang depression originated from secondaryalteration(include oxidative degradation and biological degradation) pf the normal crudeoils, i.e both heavy oils of NW slope and normal crude oil of center-southern part of the basin have the same source. While the normal crude oil was migrated, accumulated and preserved in the shallow reservoirs of NW slope of the basin, it suffered secondary alteration and formed the heavy oil progressively.
1991, 9(S1): 120-124.
Abstract:
The potential of hydrocarbon generation of Eogene source rock in Damintun depression. Liaohe oilfield, were systematically studied. Among them the type III organic matter is of following several features. Firstly, the maturation rate of it is slow. An increment of 1000m in burial depth only corresponds to an increment of 0.2% in vitrinite reflectance according to the regressive equatiion. So the oil generation zone of the source rock is very wide. Secondly, no obvious relationship between the group section of the liquid products of thermal simulation and the evolution degree of the organic matter exists. The products is rich in resin and asphltene. This is similar to that of bitumen A of the source rock. Finally, no remarkable difference of the potential of hydrocarbon generation appear at different evolution stages. No obvious stages and peak of hydrocarbon generation occur. The period of hydrocarbon generation last quite long. The deadline of oil generation is beyond R0 = 2%. All of the features mentioned above show that type III source rock in Damintun depression is of a really peculiar pattern of hydrocarbon generation, which differs from the traditional ones.
The potential of hydrocarbon generation of Eogene source rock in Damintun depression. Liaohe oilfield, were systematically studied. Among them the type III organic matter is of following several features. Firstly, the maturation rate of it is slow. An increment of 1000m in burial depth only corresponds to an increment of 0.2% in vitrinite reflectance according to the regressive equatiion. So the oil generation zone of the source rock is very wide. Secondly, no obvious relationship between the group section of the liquid products of thermal simulation and the evolution degree of the organic matter exists. The products is rich in resin and asphltene. This is similar to that of bitumen A of the source rock. Finally, no remarkable difference of the potential of hydrocarbon generation appear at different evolution stages. No obvious stages and peak of hydrocarbon generation occur. The period of hydrocarbon generation last quite long. The deadline of oil generation is beyond R0 = 2%. All of the features mentioned above show that type III source rock in Damintun depression is of a really peculiar pattern of hydrocarbon generation, which differs from the traditional ones.
1991, 9(S1): 131-137.
Abstract:
Thermal transformation of three types of spora and pollen has been conducted to evalute their generation potential of hydrocarbons. Experimental results show that the spora and pollen are source of oil and gas generation. Highest oil and gas generating rate of angiosperm pollen are 170mgHC/g Corgand 150ml/g Corgrespectively, and that of herb pteridopgyte spora are 66. lmgHC/g Corgand 11.4ml/g. 300℃ -400℃ are maturational period of hydrocarbon generation of spora and pollen. The thermal degradation of sporopollenin is the major origin of hydrocarbons generation. Angiosperm pollen is better than herb pteridophte spora in portential of hydrocarbon generation. For same kind of pollen the larger the size of pollen, the better the veins grow, the thicker the outer wall is, the better the generation potential of hydrocarbons. The contain of asphalt of generated by the three types of sporopollen in thermal degration is higher.
Thermal transformation of three types of spora and pollen has been conducted to evalute their generation potential of hydrocarbons. Experimental results show that the spora and pollen are source of oil and gas generation. Highest oil and gas generating rate of angiosperm pollen are 170mgHC/g Corgand 150ml/g Corgrespectively, and that of herb pteridopgyte spora are 66. lmgHC/g Corgand 11.4ml/g. 300℃ -400℃ are maturational period of hydrocarbon generation of spora and pollen. The thermal degradation of sporopollenin is the major origin of hydrocarbons generation. Angiosperm pollen is better than herb pteridophte spora in portential of hydrocarbon generation. For same kind of pollen the larger the size of pollen, the better the veins grow, the thicker the outer wall is, the better the generation potential of hydrocarbons. The contain of asphalt of generated by the three types of sporopollen in thermal degration is higher.
1991, 9(S1): 147-151.
Abstract:
The Confocal Laser Scanning Microscopy(CLSM) is a new generation of optical microscopy. It prossesses the characteristics of convention optical microscopy as well as scanning electron microscopy, and has a series of special functions such as high magnification, high resolution, any section scanning with some depth and the reconstruction of three dimension image. It can be used to study the microstructure and the stereo image of matter, and take three dimension measurements. In this paper, the typical hydrocarbon source rocks(coals, oil shales, and oil source rooks) are investigated with the CLSM. The rimary results show this instrument has a wide application in oil and gas evaluation. It help not only to go deep into the understanding of many problems, but also to expose a lot of new geological information. The most merits of the instrument are in that a comprehensive evaluation of a source rock can be made directly by its whole rock polished blocks, which include the determination of the abundance, types, characteristics and origins of organic matter, the study of the hydrocarbon generation and migration, and the explaination of many other petroleum geological problems. Moreover, CLSM can also study some problems which are unsolved by common optical microscopy and scanning electron microscopy. For examples, it can investigate the occurence of dispersed organic matter in a source rock, study the porosity structure and evaluate fluid inclusion, particularly organic inclusions. It is pointed out that CLSM will be very important to promote the development of mineralogy, mineragraphy, petrology and other geological sciences, and to solve some related geological problems.
The Confocal Laser Scanning Microscopy(CLSM) is a new generation of optical microscopy. It prossesses the characteristics of convention optical microscopy as well as scanning electron microscopy, and has a series of special functions such as high magnification, high resolution, any section scanning with some depth and the reconstruction of three dimension image. It can be used to study the microstructure and the stereo image of matter, and take three dimension measurements. In this paper, the typical hydrocarbon source rocks(coals, oil shales, and oil source rooks) are investigated with the CLSM. The rimary results show this instrument has a wide application in oil and gas evaluation. It help not only to go deep into the understanding of many problems, but also to expose a lot of new geological information. The most merits of the instrument are in that a comprehensive evaluation of a source rock can be made directly by its whole rock polished blocks, which include the determination of the abundance, types, characteristics and origins of organic matter, the study of the hydrocarbon generation and migration, and the explaination of many other petroleum geological problems. Moreover, CLSM can also study some problems which are unsolved by common optical microscopy and scanning electron microscopy. For examples, it can investigate the occurence of dispersed organic matter in a source rock, study the porosity structure and evaluate fluid inclusion, particularly organic inclusions. It is pointed out that CLSM will be very important to promote the development of mineralogy, mineragraphy, petrology and other geological sciences, and to solve some related geological problems.
1991, 9(S1): 163-170.
Abstract:
Either in the primary or the second migration stages, hydrocarbons could be trapped as organic inclusions, which are the direct indicators of abundance, evolution and migration of oil/gas, so long as crystallization or recrystallization takes place in the sediments. Based on the comparative studies of organic inclusions in industrial reservoir beds, oil/gas show beds and non-oil/ gas beds in carbonate rocks in China, many inclusion indices for oil/ gas potential assessment are preliminarily concluded as follows: Types and characteristics of organic inclusions: In industrial oil reservoir beds, pure liquid hydrocarbons or liquid hydrocarbons with minor gas hydrocarbons dominate in organic inclusions, liquid phase could be over 60% in inclusion volume, their colours are mostly yellow or yellowish brown with bright yellow, yellow or brownish yellow fluorescence. It must be under -140℃ while cooling if they get frozen; while in industrial gas reservoir beds, pure gas hydrocarbons or gas hydrocarbons dominate the oragnic inclusions, and gas phase can be over 80% in inclusion volume, the inclusions are mostly near round with grey black colour. The main compositions are shown by cooling to be methane with no fluorescence or liquid hydrocarbons with dark blue fluorescence. Numbers of organic inclusions: The relative abundance of organic inclusions and the saline water inclusions of the corresponding period may indicate the content of hydrocarbons in the ore-bearing fluids. According to the statistical results, the number of organic inclusion in industrial oil/gas reservoir beds are 2-3 times more than that in oil/gas show beds and over 4 times more than that in non-oil/gas beds. Palaeotemperature of inclusions: The process in which hydrocarbons are released from oil-generating rocks and accumulated into the oil/gas reservoirs is related directly to the temperature. Based on the results from actual measruements, the palaeotemperature of industrial gas reservoir beds are mainly 150℃ - 250℃, in comparison with 97-161℃ in industrial oil-reservoir and 61-110℃ in immature or low mature oil beds. Composition of inclusions: The composition of inclusions may present the primary contents of ore-bearing fluids. The main gas composition of inclusions, the contents, ratios, redox parameters or humidity etc. of organic gases are all excellent indices for their own peculiarity and characteristics. For instance, C1/C2 of inclusions from industrial oil beds is 2-10, humidity is over 20, redox parameter is 0.5-1.0; while C1/C2 of inclusions from industrial gas reservoir beds is 10-35, humidity is less than 10, and redox parameter is over 1.0. The above-mentioned indices were used to assess the oil/gas potentials of the known or unknown areas and single-wells with satisfying results, which were consilient with the research results from other organic geochemical methods and the actusl results of log-measurings. The practice confirms that organic inclusion is a new technique, which is precise, economic and easy to develop, although some aspects still need further investigations.
Either in the primary or the second migration stages, hydrocarbons could be trapped as organic inclusions, which are the direct indicators of abundance, evolution and migration of oil/gas, so long as crystallization or recrystallization takes place in the sediments. Based on the comparative studies of organic inclusions in industrial reservoir beds, oil/gas show beds and non-oil/ gas beds in carbonate rocks in China, many inclusion indices for oil/ gas potential assessment are preliminarily concluded as follows: Types and characteristics of organic inclusions: In industrial oil reservoir beds, pure liquid hydrocarbons or liquid hydrocarbons with minor gas hydrocarbons dominate in organic inclusions, liquid phase could be over 60% in inclusion volume, their colours are mostly yellow or yellowish brown with bright yellow, yellow or brownish yellow fluorescence. It must be under -140℃ while cooling if they get frozen; while in industrial gas reservoir beds, pure gas hydrocarbons or gas hydrocarbons dominate the oragnic inclusions, and gas phase can be over 80% in inclusion volume, the inclusions are mostly near round with grey black colour. The main compositions are shown by cooling to be methane with no fluorescence or liquid hydrocarbons with dark blue fluorescence. Numbers of organic inclusions: The relative abundance of organic inclusions and the saline water inclusions of the corresponding period may indicate the content of hydrocarbons in the ore-bearing fluids. According to the statistical results, the number of organic inclusion in industrial oil/gas reservoir beds are 2-3 times more than that in oil/gas show beds and over 4 times more than that in non-oil/gas beds. Palaeotemperature of inclusions: The process in which hydrocarbons are released from oil-generating rocks and accumulated into the oil/gas reservoirs is related directly to the temperature. Based on the results from actual measruements, the palaeotemperature of industrial gas reservoir beds are mainly 150℃ - 250℃, in comparison with 97-161℃ in industrial oil-reservoir and 61-110℃ in immature or low mature oil beds. Composition of inclusions: The composition of inclusions may present the primary contents of ore-bearing fluids. The main gas composition of inclusions, the contents, ratios, redox parameters or humidity etc. of organic gases are all excellent indices for their own peculiarity and characteristics. For instance, C1/C2 of inclusions from industrial oil beds is 2-10, humidity is over 20, redox parameter is 0.5-1.0; while C1/C2 of inclusions from industrial gas reservoir beds is 10-35, humidity is less than 10, and redox parameter is over 1.0. The above-mentioned indices were used to assess the oil/gas potentials of the known or unknown areas and single-wells with satisfying results, which were consilient with the research results from other organic geochemical methods and the actusl results of log-measurings. The practice confirms that organic inclusion is a new technique, which is precise, economic and easy to develop, although some aspects still need further investigations.
1991, 9(S1): 178-186.
Abstract:
This paper deal with trace elements' sedimentary geochemistry and distribution of gold of Banna Formation, Middle Triassic in Northwest Guangxi. The formation is deep sea turbidite, with four petrological parts and 150-5000m thick, main petrologic types are sand stone, silt stone, mud stone and marl. Based on statistics of gold concentration of 240 samples collected from 11 field sections, the distribution of gold in the formation is classified into 6 types original, slightly uneven lean, seriously lean, slightly uneven enriched,0 middle-degree unevenly lean and middle-degree unevenly enriched type. Regional distribution of gold is classified into original, lean and enriched rigion. Nandan geological section which is located in the gold enriched region has different characteristics of petrological chemical composition, REE and trace elements from other sections, which indicate that the sedimentary source of Nandan section(and other sections in gold en- riched region) is different from that of others. Siderofile elements(Fe,Mg,Ti,Co,Cr,Ni,V) in the stratum are lower and lithofile elements(Li,Be,Th) are higher than the mean value in crust, gold concentration correlated with that of Li and Cd in the strata and in the ore of Karlin-type gold ore deposite hosted in the strata. Trace elements in marl mainly concentrated in mud and have the same compositional character as that of detrital rocks, that illustrate that mud in marl had the same source as detrital rocks. Mn,P,Cu,Pb,Sr,Cd are compairly enriched in marl, concentrations of S,As are lower and Sb is near compair with the mean value of the same rocks in the world, but S,As,Sb have much higher variation coefficient than other elements, which show that those elements are mobile and easy to migrate, forming ore deposits or being host elements in Karlin-type gold ore deposits.
This paper deal with trace elements' sedimentary geochemistry and distribution of gold of Banna Formation, Middle Triassic in Northwest Guangxi. The formation is deep sea turbidite, with four petrological parts and 150-5000m thick, main petrologic types are sand stone, silt stone, mud stone and marl. Based on statistics of gold concentration of 240 samples collected from 11 field sections, the distribution of gold in the formation is classified into 6 types original, slightly uneven lean, seriously lean, slightly uneven enriched,0 middle-degree unevenly lean and middle-degree unevenly enriched type. Regional distribution of gold is classified into original, lean and enriched rigion. Nandan geological section which is located in the gold enriched region has different characteristics of petrological chemical composition, REE and trace elements from other sections, which indicate that the sedimentary source of Nandan section(and other sections in gold en- riched region) is different from that of others. Siderofile elements(Fe,Mg,Ti,Co,Cr,Ni,V) in the stratum are lower and lithofile elements(Li,Be,Th) are higher than the mean value in crust, gold concentration correlated with that of Li and Cd in the strata and in the ore of Karlin-type gold ore deposite hosted in the strata. Trace elements in marl mainly concentrated in mud and have the same compositional character as that of detrital rocks, that illustrate that mud in marl had the same source as detrital rocks. Mn,P,Cu,Pb,Sr,Cd are compairly enriched in marl, concentrations of S,As are lower and Sb is near compair with the mean value of the same rocks in the world, but S,As,Sb have much higher variation coefficient than other elements, which show that those elements are mobile and easy to migrate, forming ore deposits or being host elements in Karlin-type gold ore deposits.
