Going deep has been the strategy for the sustainable development of the Tahe Oilfield.Following the TS1 well in block 1,which revealed excellent combinations of hydrocarbon generation,migration and accumulation in the...Going deep has been the strategy for the sustainable development of the Tahe Oilfield.Following the TS1 well in block 1,which revealed excellent combinations of hydrocarbon generation,migration and accumulation in the deeper parts of the Tarim Basin,the TS2 well was drilled to learn more about the prospectivity in the deeper parts of the main blocks of the Tahe Oilfield.Seventeen core samples were collected to perform fluid inclusion studies,including petrography,fluorescence microspectrometry,and microthermometry.The results show that the deeper parts of the Tahe Oilfield have a good hydrocarbon potential.The Cambrian source rocks can supply sufficient oil for not only the Cambrian reservoirs,but also for the Lower Ordovician reservoirs.The CambrianOrdovician carbonates reservoirs experienced at least three oil charging events and one late gas charging event.Oil accumulations formed in the early stage of basin evolution were likely destroyed in the late stage with deep burial,tectonic movements,or invasion of hydrothermal fluids.Therefore,the deep hydrocarbon exploration of the Tahe Oilfield,even the whole Tarim Basin,should focus on gas accumulations,although oil accumulations,especially in Cambrian reservoirs,cannot be neglected.展开更多
Various early Paleozoic （Cambrian Series 3-Middle Ordovician） reefs are found in the Taebaek Group, eastern Korea, located in the eastern margin of the Sino-Korean Block. They occur in every carbonate-dominant litho...Various early Paleozoic （Cambrian Series 3-Middle Ordovician） reefs are found in the Taebaek Group, eastern Korea, located in the eastern margin of the Sino-Korean Block. They occur in every carbonate-dominant lithostratigraphic unit of the group, but their morphology and composition differ markedly. The Daegi Formation （middle Cambrian： Cambrian Series 3） contains siliceous sponge-Epiphyton reefs formed in a shallow subtidal environment, which is one of the earliest metazoan-bearing microbial reefs after the archaeocyath extinction. The Hwajeol Formation （upper Cambrian： Furongian） encloses sporadic dendrolites consisting of Angulocellularia, which developed in a relatively deep subtidal environment, representing a rare deeper water example. The onset of the Ordovician radiation resulted in the formation of microbialite-Archaeoscyphia-calathiid patch reefs in shallow subtidal deposits of the Lower Ordovician Dumugol Formation. Subsequent late Early Ordovician relative sea-level fall established extensive peritidal environments, forming microbial mats and stromatolites of the Lower-Middle Ordovician Makgol Formation. Ensuing Ordovician radiation resulted in one of the earliest metazoan skeletal reefs of the Middle Ordovician Duwibong Formation, constructed by stromatoporoid Cystostroma and bryozoan Nicholsonella, and developed around shallow shoals. These reefs reflect ongoing evolution and sea-level change during the early Paleozoic, and exemplify a rare glimpse of peri-Gondwanan records of reef evolution, which warrant detailed investigations and comparison with their counterparts in other regions.展开更多
8,14-secohopanes in the marine oils from the Tazhong area in the Tarim Basin are detected by gas chromatography-mass spectrometry(GC-MS)and gas chromatography-mass spectrometry-mass spectrometry(GC-MS-MS),and their di...8,14-secohopanes in the marine oils from the Tazhong area in the Tarim Basin are detected by gas chromatography-mass spectrometry(GC-MS)and gas chromatography-mass spectrometry-mass spectrometry(GC-MS-MS),and their distributions and compositions are compared in order to study their potential significances in oil-source correlation.C35+extended hopane series and three series of extended 8,14-secohopanes can be detected in two kinds of end-member oils in the Tazhong area in the Tarim Basin,and they are different in distribution,suggesting that they may have some special geochemical significance.The presence of 8,14-secohopanes in two kinds of end-member oils in the Tarim Basin suggests that these biomarkers are primary,and not related to biodegradation.The relative abundance of 8,14-secohopanes in the type-A oil is much less than that in the type-B oil,and the 8,14-secohopanes content in end-member oils is much less than that in the corresponding mixed oils.Based on the relative contents of 8,14-secohopanes and the compositions of common steranes and triterpanes,it is very effective to distinguish different crude oils from the Tazhong area.The great difference in the relative abundance of 8,14-secohopanes between the type-A oil and type-B oil suggests that their formation may require some specific geological-geochemical conditions.展开更多
The Caledonian North Qilian orogenic belt lies between the North China plate and the Qaidam mi-croplates, and resulted from the collision among the Qaidam microplate, mid-Qilian block and the North China plate. The or...The Caledonian North Qilian orogenic belt lies between the North China plate and the Qaidam mi-croplates, and resulted from the collision among the Qaidam microplate, mid-Qilian block and the North China plate. The orogen initiated from the rifting of the Late Proterozoic Rodinia, and then it experi-enced stages of Cambrian rift basin and Ordovician archipelagic oceanic basin, and foreland basin during Silurian to Early-Middle Devonian. The average ratios of Al/(Al+Fe+Mn), Al/(Al+Fe), δ Ce, Lan/Ybn and Lan/Cen from cherts of Cambrian Heicigou Formation are 0.797, 0.627, 1.114, 0.994 and 1.034 re-spectively. In the NAS standardized REE distribution pattern, the cherts from Xiangqianshan is slightly HREE enriched, and the cherts from Ganluci and Shiqingdong are plane. All of these features indicated that Cambrian cherts of the Heicigou Formation originated from a continental margin rift background. On the contrary, the average ratios of Al/(Al+Fe+Mn), Al/(Al+Fe), δ Ce, Lan/Ybn, Lan/Cen of the Ordovician chert from Dakecha, Cuijiadun, Shihuigou, Laohushan, Heicigou, Maomaoshan, Bianmagou, Da-chadaban, Baiquanmen, Jiugequan and Angzanggou, are respectively 0.72, 0.58, 0.99, 1.09 and 0.96 respectively. Their NAS standardized REE distribution patterns of most Ordovician cherts are plane mode or slightly HREE enriched. The REE distribution pattern of few samples of cherts are slightly LREE enriched. Characteristics of sedimentary geochemistry and tectonic evolution demonstrated that the Cambrian-Ordovician cherts, associated with rift, oceanic, island arc and back-arc volcanic rocks, was not formed in a typical abyssal oceanic basin or mid-oceanic ridge. On the contrary, they formed in a deepwater basin of continental margin or a archipelagic ocean tectonic setting. Several Early Paleo-zoic ophiolite belts in North Qilian and adjacent periphery Qaidam microplate imply that an archipelagic ocean during Ordovician existed in the east of Pro-Tethys.展开更多
Biostratigraphically constrained sequences at the Wushi Yingshan and Kalpin Cement Plant sections (Kalpin Region; Tarim Basin) were densely sampled for geochemical studies. Carbonates across the Cambrian-Ordovician bo...Biostratigraphically constrained sequences at the Wushi Yingshan and Kalpin Cement Plant sections (Kalpin Region; Tarim Basin) were densely sampled for geochemical studies. Carbonates across the Cambrian-Ordovician boundary of both sections mainly record negative carbon isotope values. Stable isotope curves show four negative and four positive excursions appearing alternately at the Wushi Yingshan section and five negative alternating with five positive excursions at the Kalpin Cement Plant section. The carbon isotope logs of these two sections are correlated with the international Cambrian-Ordovician boundary key sections: (1) Dayangcha section in China, (2) Green Point section in Canada, (3) Black mountain section in Australia and (4) Lowson Cove section in USA. These correlations suggest that the Cambrian-Ordovician boundary of the Wushi Yingshan section and the Kalpin Cement Plant section can be placed within a particular horizon that also corresponds to the observed biostratigraphic units.展开更多
The Cambrian and Ordovician on the northern Tarim Platform are mainly composed of carbonates. On the basis of detailed outcrop analysis, the sequence stratigraphic system of the Cambrian-Ordovician in the northern Tar...The Cambrian and Ordovician on the northern Tarim Platform are mainly composed of carbonates. On the basis of detailed outcrop analysis, the sequence stratigraphic system of the Cambrian-Ordovician in the northern Tarim Platform is outlined in this paper. Altogether 35 third-order sequences, 12 supersequences, 4 supersequence sets and 2 megasequences are recognized. The characteristics of the major sequence boundaries have been documented with an integrated examination of outcrop, seismic and borehole data, and the ages of these sequence boundaries have been calibrated through the combination of sequence stratigraphy with biostratigraphy. It is discovered that there is good correlation of the sequence stratigraphy of the Cambrian-Ordovician among Tarim, Yangtze and North China platforms. This may illustrate that the development of the Cambrian-Ordovician carbonate sequences in these three platforms is mainly controlled by regional or global sea level changes. This forms the theoretical basis for the construction of high-resolution chronostratigraphic system of the Cambrian-Ordovician in the three platforms in China.展开更多
基金supported by National Basic Research Program of China(Grant No.2012CB214804)the Fundamental Research Funds for the Central Universities, China University of Geosciences(Wuhan)(Grant No. cug130104)
文摘Going deep has been the strategy for the sustainable development of the Tahe Oilfield.Following the TS1 well in block 1,which revealed excellent combinations of hydrocarbon generation,migration and accumulation in the deeper parts of the Tarim Basin,the TS2 well was drilled to learn more about the prospectivity in the deeper parts of the main blocks of the Tahe Oilfield.Seventeen core samples were collected to perform fluid inclusion studies,including petrography,fluorescence microspectrometry,and microthermometry.The results show that the deeper parts of the Tahe Oilfield have a good hydrocarbon potential.The Cambrian source rocks can supply sufficient oil for not only the Cambrian reservoirs,but also for the Lower Ordovician reservoirs.The CambrianOrdovician carbonates reservoirs experienced at least three oil charging events and one late gas charging event.Oil accumulations formed in the early stage of basin evolution were likely destroyed in the late stage with deep burial,tectonic movements,or invasion of hydrothermal fluids.Therefore,the deep hydrocarbon exploration of the Tahe Oilfield,even the whole Tarim Basin,should focus on gas accumulations,although oil accumulations,especially in Cambrian reservoirs,cannot be neglected.
基金supported by a Korea University Grant to JHL and JHby Korean Ministry of Oceans and Fisheries(KOPRI,PM14030) to JW+2 种基金by the National Research Foundation of Korea(NRF-2013R1A2A2A 01067612) to DJLby the National Research Foundation of Korea(NRF-2015R1A2A2A01007063)a grant from Korea Institute of Energy Technology Evaluation and Planning and Ministry of Knowledge and Economy(2011201030006B) to SJC
文摘Various early Paleozoic （Cambrian Series 3-Middle Ordovician） reefs are found in the Taebaek Group, eastern Korea, located in the eastern margin of the Sino-Korean Block. They occur in every carbonate-dominant lithostratigraphic unit of the group, but their morphology and composition differ markedly. The Daegi Formation （middle Cambrian： Cambrian Series 3） contains siliceous sponge-Epiphyton reefs formed in a shallow subtidal environment, which is one of the earliest metazoan-bearing microbial reefs after the archaeocyath extinction. The Hwajeol Formation （upper Cambrian： Furongian） encloses sporadic dendrolites consisting of Angulocellularia, which developed in a relatively deep subtidal environment, representing a rare deeper water example. The onset of the Ordovician radiation resulted in the formation of microbialite-Archaeoscyphia-calathiid patch reefs in shallow subtidal deposits of the Lower Ordovician Dumugol Formation. Subsequent late Early Ordovician relative sea-level fall established extensive peritidal environments, forming microbial mats and stromatolites of the Lower-Middle Ordovician Makgol Formation. Ensuing Ordovician radiation resulted in one of the earliest metazoan skeletal reefs of the Middle Ordovician Duwibong Formation, constructed by stromatoporoid Cystostroma and bryozoan Nicholsonella, and developed around shallow shoals. These reefs reflect ongoing evolution and sea-level change during the early Paleozoic, and exemplify a rare glimpse of peri-Gondwanan records of reef evolution, which warrant detailed investigations and comparison with their counterparts in other regions.
基金Supported by the national Natural Science Foundation of China(41772119,41272169)。
文摘8,14-secohopanes in the marine oils from the Tazhong area in the Tarim Basin are detected by gas chromatography-mass spectrometry(GC-MS)and gas chromatography-mass spectrometry-mass spectrometry(GC-MS-MS),and their distributions and compositions are compared in order to study their potential significances in oil-source correlation.C35+extended hopane series and three series of extended 8,14-secohopanes can be detected in two kinds of end-member oils in the Tazhong area in the Tarim Basin,and they are different in distribution,suggesting that they may have some special geochemical significance.The presence of 8,14-secohopanes in two kinds of end-member oils in the Tarim Basin suggests that these biomarkers are primary,and not related to biodegradation.The relative abundance of 8,14-secohopanes in the type-A oil is much less than that in the type-B oil,and the 8,14-secohopanes content in end-member oils is much less than that in the corresponding mixed oils.Based on the relative contents of 8,14-secohopanes and the compositions of common steranes and triterpanes,it is very effective to distinguish different crude oils from the Tazhong area.The great difference in the relative abundance of 8,14-secohopanes between the type-A oil and type-B oil suggests that their formation may require some specific geological-geochemical conditions.
基金Sponsored by the National Natural Science Foundation of China (Grant Nos. 40672080 and 40621002)the Developing Plan of Innovation Group of Ministry of Education of China (Grant No. IRT0546)
文摘The Caledonian North Qilian orogenic belt lies between the North China plate and the Qaidam mi-croplates, and resulted from the collision among the Qaidam microplate, mid-Qilian block and the North China plate. The orogen initiated from the rifting of the Late Proterozoic Rodinia, and then it experi-enced stages of Cambrian rift basin and Ordovician archipelagic oceanic basin, and foreland basin during Silurian to Early-Middle Devonian. The average ratios of Al/(Al+Fe+Mn), Al/(Al+Fe), δ Ce, Lan/Ybn and Lan/Cen from cherts of Cambrian Heicigou Formation are 0.797, 0.627, 1.114, 0.994 and 1.034 re-spectively. In the NAS standardized REE distribution pattern, the cherts from Xiangqianshan is slightly HREE enriched, and the cherts from Ganluci and Shiqingdong are plane. All of these features indicated that Cambrian cherts of the Heicigou Formation originated from a continental margin rift background. On the contrary, the average ratios of Al/(Al+Fe+Mn), Al/(Al+Fe), δ Ce, Lan/Ybn, Lan/Cen of the Ordovician chert from Dakecha, Cuijiadun, Shihuigou, Laohushan, Heicigou, Maomaoshan, Bianmagou, Da-chadaban, Baiquanmen, Jiugequan and Angzanggou, are respectively 0.72, 0.58, 0.99, 1.09 and 0.96 respectively. Their NAS standardized REE distribution patterns of most Ordovician cherts are plane mode or slightly HREE enriched. The REE distribution pattern of few samples of cherts are slightly LREE enriched. Characteristics of sedimentary geochemistry and tectonic evolution demonstrated that the Cambrian-Ordovician cherts, associated with rift, oceanic, island arc and back-arc volcanic rocks, was not formed in a typical abyssal oceanic basin or mid-oceanic ridge. On the contrary, they formed in a deepwater basin of continental margin or a archipelagic ocean tectonic setting. Several Early Paleo-zoic ophiolite belts in North Qilian and adjacent periphery Qaidam microplate imply that an archipelagic ocean during Ordovician existed in the east of Pro-Tethys.
基金the Tarim Oilfield Company, PetroChina, the Innovating Foundation of Research Institute of Petroleum Exploration & Development, PetroChina and the Outstanding Doctoral Dissertation Support Foundation of China University of Geo-sciences (Beijing)
文摘Biostratigraphically constrained sequences at the Wushi Yingshan and Kalpin Cement Plant sections (Kalpin Region; Tarim Basin) were densely sampled for geochemical studies. Carbonates across the Cambrian-Ordovician boundary of both sections mainly record negative carbon isotope values. Stable isotope curves show four negative and four positive excursions appearing alternately at the Wushi Yingshan section and five negative alternating with five positive excursions at the Kalpin Cement Plant section. The carbon isotope logs of these two sections are correlated with the international Cambrian-Ordovician boundary key sections: (1) Dayangcha section in China, (2) Green Point section in Canada, (3) Black mountain section in Australia and (4) Lowson Cove section in USA. These correlations suggest that the Cambrian-Ordovician boundary of the Wushi Yingshan section and the Kalpin Cement Plant section can be placed within a particular horizon that also corresponds to the observed biostratigraphic units.
基金This project was jointly supported by the Ministry of Science and Technology of China (GrantNo. G1999043304) and the Key Project "SSER" for basic studies (Grant No. 95-04). The authors are grateful to Prof. Wang Hongzhen and Prof. Yue Changshuo for the
文摘The Cambrian and Ordovician on the northern Tarim Platform are mainly composed of carbonates. On the basis of detailed outcrop analysis, the sequence stratigraphic system of the Cambrian-Ordovician in the northern Tarim Platform is outlined in this paper. Altogether 35 third-order sequences, 12 supersequences, 4 supersequence sets and 2 megasequences are recognized. The characteristics of the major sequence boundaries have been documented with an integrated examination of outcrop, seismic and borehole data, and the ages of these sequence boundaries have been calibrated through the combination of sequence stratigraphy with biostratigraphy. It is discovered that there is good correlation of the sequence stratigraphy of the Cambrian-Ordovician among Tarim, Yangtze and North China platforms. This may illustrate that the development of the Cambrian-Ordovician carbonate sequences in these three platforms is mainly controlled by regional or global sea level changes. This forms the theoretical basis for the construction of high-resolution chronostratigraphic system of the Cambrian-Ordovician in the three platforms in China.
