2015 Vol. 33, No. 2
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Display Method:
2015, 33(2): 211-225.
doi: 10.14027/j.cnki.cjxb.2015.02.001
Abstract:
Trace fossils from Ordovician Majiagou Formation consist of at least 10 ichnogenera and 17 ichnospecies, namely, (1)Domichnia: Psilonichnus upsilon, Thalassinoides callianassa, Thalassinoides horizontalis, Rhizocorallium jenense.(2)Foidichnia: Chondrites type-1, Chondrites type-2, Chondrites intricatus, Palaeophycus tubularis, Palaeophycus heberti, Planolites montanus, Planolites annularius, Phycodes palmatus.(3)Pascichnia: Helminthopsis ichnosp., Helminthopsis abeli, Helminthopsis hieroglyphica, Gordia molassica, Scolicia ichnosp. According to their palaeoecological and sedimentological features, these trace fossils can be divided into 3 ichnoassemblags, ie,①Psilonichnus-Thalassinoides ichnoassemblage, forming in tidal sedimentary environment of Restricted carbonate platform, mainly composed of Psilonichnus ,Thalassinoides, Helminthopsis. ②Helminthopsis-Gordia ichnoassemblage, which is associated with lagoon sedimentary environment of restricted carbonate platform, interbank sea or depression of open carbonate rock platform, mainly composed of Helminthopsis, Gordia, planolites, Palaeophycus, Thalassinoides. ③Chondrites-Scolica ichnoassemblage, which indicates the depression of open carbonate rock platform near the REDOX interface. Finally, depositional model of the Ordovician Majiagou Group and the vertical sedimentary evolution sequence was established based on integrated rock types, rock sequence, sedimentary structure, fossils with trace fossils or ichnoassemblage.
Trace fossils from Ordovician Majiagou Formation consist of at least 10 ichnogenera and 17 ichnospecies, namely, (1)Domichnia: Psilonichnus upsilon, Thalassinoides callianassa, Thalassinoides horizontalis, Rhizocorallium jenense.(2)Foidichnia: Chondrites type-1, Chondrites type-2, Chondrites intricatus, Palaeophycus tubularis, Palaeophycus heberti, Planolites montanus, Planolites annularius, Phycodes palmatus.(3)Pascichnia: Helminthopsis ichnosp., Helminthopsis abeli, Helminthopsis hieroglyphica, Gordia molassica, Scolicia ichnosp. According to their palaeoecological and sedimentological features, these trace fossils can be divided into 3 ichnoassemblags, ie,①Psilonichnus-Thalassinoides ichnoassemblage, forming in tidal sedimentary environment of Restricted carbonate platform, mainly composed of Psilonichnus ,Thalassinoides, Helminthopsis. ②Helminthopsis-Gordia ichnoassemblage, which is associated with lagoon sedimentary environment of restricted carbonate platform, interbank sea or depression of open carbonate rock platform, mainly composed of Helminthopsis, Gordia, planolites, Palaeophycus, Thalassinoides. ③Chondrites-Scolica ichnoassemblage, which indicates the depression of open carbonate rock platform near the REDOX interface. Finally, depositional model of the Ordovician Majiagou Group and the vertical sedimentary evolution sequence was established based on integrated rock types, rock sequence, sedimentary structure, fossils with trace fossils or ichnoassemblage.
2015, 33(2): 232-241.
doi: 10.14027/j.cnki.cjxb.2015.02.003
Abstract:
The global glaciation happened in Hirnantian of the Late Ordovician, the lithofacies, biologic facies and sedimentary environment of Hirnantian Kuanyinchiao Formation in the eastern Chongqing and northern Guizhou region, were the response to the glacial event. There were 3 types of lithofacies as a whole. The first type was composed of grainstone with coral. could be subdivided into bioclast limestone, calcarenite, oolitic sparite limestone and spararenite. Which formed in the shoal with medium to high energy. The major components of the second one were the silty limestone and silty argillaceous limestone that formed in tidal flat, where the plentiful brachiopoda and a few trilobites lived. These two types of lithofacies were both the inshore carbonate sediments resulted from sea level drop. The associations of marlstone and calcareous shale, argillaceous siltstone and silty mudstone, and the carbonous marlstone, constituted the last type. And its mixed biofacies containing brachiopoda, trilobites, graptolite, especially the bloomed Hirnantia fauna, indicated the cold water environment and temperature drop of seawater in Principal Glacial Age (Hirnantian). The tidal flat distributed near the Qianzhong(Central Guizhou)Uplift, and the shoal also occupied local area upon the tidal flat, and shallow shelf distributed far away from uplift. As a whole, the sedimentary environment of Kuanyinqiao Formation was shallower than the black shales of Wufeng Formation and Longmaxi Formation formed in anoxic deep-water shelf, the sea-level and seawater temperature was much lower in Hirnantian. All of which were the results influenced by the glacier events in Hirnantian.
The global glaciation happened in Hirnantian of the Late Ordovician, the lithofacies, biologic facies and sedimentary environment of Hirnantian Kuanyinchiao Formation in the eastern Chongqing and northern Guizhou region, were the response to the glacial event. There were 3 types of lithofacies as a whole. The first type was composed of grainstone with coral. could be subdivided into bioclast limestone, calcarenite, oolitic sparite limestone and spararenite. Which formed in the shoal with medium to high energy. The major components of the second one were the silty limestone and silty argillaceous limestone that formed in tidal flat, where the plentiful brachiopoda and a few trilobites lived. These two types of lithofacies were both the inshore carbonate sediments resulted from sea level drop. The associations of marlstone and calcareous shale, argillaceous siltstone and silty mudstone, and the carbonous marlstone, constituted the last type. And its mixed biofacies containing brachiopoda, trilobites, graptolite, especially the bloomed Hirnantia fauna, indicated the cold water environment and temperature drop of seawater in Principal Glacial Age (Hirnantian). The tidal flat distributed near the Qianzhong(Central Guizhou)Uplift, and the shoal also occupied local area upon the tidal flat, and shallow shelf distributed far away from uplift. As a whole, the sedimentary environment of Kuanyinqiao Formation was shallower than the black shales of Wufeng Formation and Longmaxi Formation formed in anoxic deep-water shelf, the sea-level and seawater temperature was much lower in Hirnantian. All of which were the results influenced by the glacier events in Hirnantian.
2015, 33(2): 254-264.
doi: 10.14027/j.cnki.cjxb.2015.02.005
Abstract:
This study shows that it was a littoral- and neritic- facies during sedimentation of the Lower Carboniferous Heishantou Formation and Nanmingshui Formation. Several sets of "basal conglomerates" developped between the two Formation and the first sub-formation of Nanmingshui. The conglomerates, usually as a shape of lens and not far-extending, are occurrences of subaqueous channel when rivers flow into the sea, but not basal conglomerates previously considered.Lateral comparison of conglomerate characteristics and the study of oblique beddings and asymmetrical ripple mark indicate that the provenance is in the direction of NE, and the paleocurrence direction concentrates in 93°-125°.The contact relationship between Heishantou Fm. and Nanmingshui Fm. is conformable and successive. It is not an unconformity of plate collision between Junggar block and Siberia plate.
This study shows that it was a littoral- and neritic- facies during sedimentation of the Lower Carboniferous Heishantou Formation and Nanmingshui Formation. Several sets of "basal conglomerates" developped between the two Formation and the first sub-formation of Nanmingshui. The conglomerates, usually as a shape of lens and not far-extending, are occurrences of subaqueous channel when rivers flow into the sea, but not basal conglomerates previously considered.Lateral comparison of conglomerate characteristics and the study of oblique beddings and asymmetrical ripple mark indicate that the provenance is in the direction of NE, and the paleocurrence direction concentrates in 93°-125°.The contact relationship between Heishantou Fm. and Nanmingshui Fm. is conformable and successive. It is not an unconformity of plate collision between Junggar block and Siberia plate.
2015, 33(2): 275-284.
doi: 10.14027/j.cnki.cjxb.2015.02.007
Abstract:
A distinct damming incident occurred at the prehistoric period(Late Holocene) in the upper Jinsha River in the Mangkang County, Xizang province, China. The volume of the dammed lake is about 3.1×108 m3. The dammed lake breached and caused a big outburst flood at about 1 117 A.D. We can infer that the paleoseismics induced major landslide may be the direct cause triggering the river damming. In the range between the downstream side of the ancient dam body to its downstream 3.5 km, abundance of diamicton consisting of gravels, sands and minor silts and clays was discovered. The sedimental structure of the dam break-outburst sediments includes gravel support-stacked structure, gravel imbricate structure and matrix structure, and so on. Besides, it has a special sedimental structure: rhythmites interbedded structure composed of coarser gravel layer and finer sand and gravel layer, no sand lens are formed in the layers. This special structure can be an important origin criteria of the dam break-outburst sediments. Based on back analysis using the hydraulic model, the average flow rate velocity of the outburst flood is 7.48 m/s and the maximum peak discharge is 10 786 m3/s. The research on the sedimentary features and its environment of the dam break-outburst sediments can not only be served to help revealing the process and mechanism of ancient flood incidents, but also be significant of knowing the environmetal evolution in the upper Jinsha River area.
A distinct damming incident occurred at the prehistoric period(Late Holocene) in the upper Jinsha River in the Mangkang County, Xizang province, China. The volume of the dammed lake is about 3.1×108 m3. The dammed lake breached and caused a big outburst flood at about 1 117 A.D. We can infer that the paleoseismics induced major landslide may be the direct cause triggering the river damming. In the range between the downstream side of the ancient dam body to its downstream 3.5 km, abundance of diamicton consisting of gravels, sands and minor silts and clays was discovered. The sedimental structure of the dam break-outburst sediments includes gravel support-stacked structure, gravel imbricate structure and matrix structure, and so on. Besides, it has a special sedimental structure: rhythmites interbedded structure composed of coarser gravel layer and finer sand and gravel layer, no sand lens are formed in the layers. This special structure can be an important origin criteria of the dam break-outburst sediments. Based on back analysis using the hydraulic model, the average flow rate velocity of the outburst flood is 7.48 m/s and the maximum peak discharge is 10 786 m3/s. The research on the sedimentary features and its environment of the dam break-outburst sediments can not only be served to help revealing the process and mechanism of ancient flood incidents, but also be significant of knowing the environmetal evolution in the upper Jinsha River area.
2015, 33(2): 299-305.
doi: 10.14027/j.cnki.cjxb.2015.02.009
Abstract:
Using Chongqing Fengdu Yangzi Cave Stalagmite Y02 ICP-MS dating data, trace element data and stalagmite oxygen isotope data reconstruct the paleoclimate and paleoenvironment of Chongqing area during 76~69ka BP periods. We have contrasted the stalagmite Y02 test data with the curve of local solar radiation, the Greenland NGRIP ice core, the surface temperature of south sea, and results show that: Mg/Ca in stalagmite response to changes in precipitation mainly, while Sr/Ca, Ba/Ca and U/Ca response to surface soil conditions and local atmospheric dust activities, and thus in response to changes in precipitation indirectly; oxygen isotope and trace elements not synchronous changes appeared in stalagmite Y02, stalagmite δ18O heavy trend appeared 1ka later than the trace element ratios increased, shows that the changes of trace element ratios also affected by temperature in stalagmite.
Using Chongqing Fengdu Yangzi Cave Stalagmite Y02 ICP-MS dating data, trace element data and stalagmite oxygen isotope data reconstruct the paleoclimate and paleoenvironment of Chongqing area during 76~69ka BP periods. We have contrasted the stalagmite Y02 test data with the curve of local solar radiation, the Greenland NGRIP ice core, the surface temperature of south sea, and results show that: Mg/Ca in stalagmite response to changes in precipitation mainly, while Sr/Ca, Ba/Ca and U/Ca response to surface soil conditions and local atmospheric dust activities, and thus in response to changes in precipitation indirectly; oxygen isotope and trace elements not synchronous changes appeared in stalagmite Y02, stalagmite δ18O heavy trend appeared 1ka later than the trace element ratios increased, shows that the changes of trace element ratios also affected by temperature in stalagmite.
2015, 33(2): 314-325.
doi: 10.14027/j.cnki.cjxb.2015.02.011
Abstract:
In order to promote progressive exploration and development in WZ10-3 Oilfield and surrounding area, the fine sedimentary facies study in oil region was carried out. Guided by the high resolution sequence stratigraphy theory, in combination with core, logging, log and seismic data, on the basis of recognition of different levels sequence interfaces and the types of maximum lake flooding surface, the Member 3 of Liushagang Formation can be divided into two long-term base level cyclical sequence and eight middle-term base level cyclical sequence. By analyses of individual well sedimentary facies, section sedimentary facies and plane sedimentary facies, 3 sedimentary facies of alluvial fan, fan delta and lacustine were identified in the Member 3 of Liushagang Formation, and microfacies were divided, facies belt ownership of debris flow deposit was discussed systematically. Debris flow deposits developing in channels were divided into 3 types, i.e., channels, distribution channels and subaqueous distribution channels microfacies. While individual developmental debris flow deposits were divided into 2 types, i.e., subaerial non-channelized and subaqueous non-channelized debris flows microfacies. On the basis of these, sedimentary facies distribution and sedimentary evolution rule of MSC1 to MSC8 of the Member 3 of Liushagang Formation were discussed, and sedimentary models were established finally.
In order to promote progressive exploration and development in WZ10-3 Oilfield and surrounding area, the fine sedimentary facies study in oil region was carried out. Guided by the high resolution sequence stratigraphy theory, in combination with core, logging, log and seismic data, on the basis of recognition of different levels sequence interfaces and the types of maximum lake flooding surface, the Member 3 of Liushagang Formation can be divided into two long-term base level cyclical sequence and eight middle-term base level cyclical sequence. By analyses of individual well sedimentary facies, section sedimentary facies and plane sedimentary facies, 3 sedimentary facies of alluvial fan, fan delta and lacustine were identified in the Member 3 of Liushagang Formation, and microfacies were divided, facies belt ownership of debris flow deposit was discussed systematically. Debris flow deposits developing in channels were divided into 3 types, i.e., channels, distribution channels and subaqueous distribution channels microfacies. While individual developmental debris flow deposits were divided into 2 types, i.e., subaerial non-channelized and subaqueous non-channelized debris flows microfacies. On the basis of these, sedimentary facies distribution and sedimentary evolution rule of MSC1 to MSC8 of the Member 3 of Liushagang Formation were discussed, and sedimentary models were established finally.
2015, 33(2): 337-347.
doi: 10.14027/j.cnki.cjxb.2015.02.013
Abstract:
Based on petrology, mineralogy and geochemistry, the diagenesis, depositional environment and origin of Miocene clastic rock of Shangganchaigou Formation in Eboliang III tectonic belt on the northern margin of the Qaidam basin were studied. The experimental results were that particles of Miocene clastic rock of Shangganchaigou Formation mainly had point contact or line contact relationships, and had been suffered strong compaction; the clastic rock of Shangganchaigou Formation had high contents of clay minerals, whose average value was 35.03%, and which were dominated by illite, chlorite and mixed layer of illite and montmorillonite; the calcite was the main types of carbonate cements, and the dolomite was minor; the carbon isotope (δ13C) of carbonate cements ranged from -6.8‰ to -4.0‰, and the average value was -5.0‰; the oxygen isotope (δ18O) ranged from -11.1‰ to -5.4‰, and the average value was -8.7‰; Z-value of paleosalinity estimated by δ13C and δ18O ranged from 108.34 to 114.89 and the average value was 112.77; and temperature of carbonate deposited ranged from 43.36℃ to 77.84℃, and the average value was 62.30℃. Above results, combined with the comprehensive analysis of some geochemical elements, such as major elements, trace elements and organic carbon content, suggested that main diagenetic stage of Miocene clastic rock of Shangganchaigou Formation in Eboliang III tectonic belt was in phase B of early diagenetic stage B or phase A of the middle diagenetic stage. The early stage of diagenesis occurred in dry environment, where the water was cold freshwater or brackish water, and to the late stage of diagenesis, the Z-value of paleosalinity of water clearly decreased, and the paleo-environment was dominated by warm and wet climate.
Based on petrology, mineralogy and geochemistry, the diagenesis, depositional environment and origin of Miocene clastic rock of Shangganchaigou Formation in Eboliang III tectonic belt on the northern margin of the Qaidam basin were studied. The experimental results were that particles of Miocene clastic rock of Shangganchaigou Formation mainly had point contact or line contact relationships, and had been suffered strong compaction; the clastic rock of Shangganchaigou Formation had high contents of clay minerals, whose average value was 35.03%, and which were dominated by illite, chlorite and mixed layer of illite and montmorillonite; the calcite was the main types of carbonate cements, and the dolomite was minor; the carbon isotope (δ13C) of carbonate cements ranged from -6.8‰ to -4.0‰, and the average value was -5.0‰; the oxygen isotope (δ18O) ranged from -11.1‰ to -5.4‰, and the average value was -8.7‰; Z-value of paleosalinity estimated by δ13C and δ18O ranged from 108.34 to 114.89 and the average value was 112.77; and temperature of carbonate deposited ranged from 43.36℃ to 77.84℃, and the average value was 62.30℃. Above results, combined with the comprehensive analysis of some geochemical elements, such as major elements, trace elements and organic carbon content, suggested that main diagenetic stage of Miocene clastic rock of Shangganchaigou Formation in Eboliang III tectonic belt was in phase B of early diagenetic stage B or phase A of the middle diagenetic stage. The early stage of diagenesis occurred in dry environment, where the water was cold freshwater or brackish water, and to the late stage of diagenesis, the Z-value of paleosalinity of water clearly decreased, and the paleo-environment was dominated by warm and wet climate.
2015, 33(2): 357-363.
doi: 10.14027/j.cnki.cjxb.2015.02.015
Abstract:
Reservoir architecture is the basis and the key that evaluating oil and gas accumulation, improving the water flood development efficiency and hydrocarbon recovery for maturing field. Therefore, this article does a research about underwater distributary channel of Chang 63 reservoir of Huaqing area. It uses the outcrop pictures and data of the well profile and PETREL software to establish the structural pattern and reservoir parameters (porosity, permeability and shale content) model of Chang 63 reservoir in Huaqing area. The results show that the architecture interface of the underwater distributary channel can be divided into five hierarchies: 5th hierarchy is the interface for composite sandbody; 4th hierarchy is the interface for the single sandbody; 3rd hierarchy is the interface for the hyperplasia of single sandbody; 2nd hierarchy is the interface for the layer system group; 1st hierarchy is the interface for the single staggered formation. The interlining of sandbody exist three types: Lateral interlining, Progradation interlining and vertical interlining. The overall trend of Chang 63 structure model is high in the east and low in the west, it can be seen that the study area belongs to low porosity and low permeability reservoir from the porosity, permeability and sand shale distribution model. This paper objectively reflects the internal distribution shape of basic unit of Chang 63 reservoir layers, and reproduced the space form distribution model of sandbody.
Reservoir architecture is the basis and the key that evaluating oil and gas accumulation, improving the water flood development efficiency and hydrocarbon recovery for maturing field. Therefore, this article does a research about underwater distributary channel of Chang 63 reservoir of Huaqing area. It uses the outcrop pictures and data of the well profile and PETREL software to establish the structural pattern and reservoir parameters (porosity, permeability and shale content) model of Chang 63 reservoir in Huaqing area. The results show that the architecture interface of the underwater distributary channel can be divided into five hierarchies: 5th hierarchy is the interface for composite sandbody; 4th hierarchy is the interface for the single sandbody; 3rd hierarchy is the interface for the hyperplasia of single sandbody; 2nd hierarchy is the interface for the layer system group; 1st hierarchy is the interface for the single staggered formation. The interlining of sandbody exist three types: Lateral interlining, Progradation interlining and vertical interlining. The overall trend of Chang 63 structure model is high in the east and low in the west, it can be seen that the study area belongs to low porosity and low permeability reservoir from the porosity, permeability and sand shale distribution model. This paper objectively reflects the internal distribution shape of basic unit of Chang 63 reservoir layers, and reproduced the space form distribution model of sandbody.
2015, 33(2): 376-384.
doi: 10.14027/j.cnki.cjxb.2015.02.017
Abstract:
Mixed sedimentary rock is referred to the rock composed of terrigenous clastics and carbonate components under mixed sedimentation. In a broad sense, it also includes the spatially alternating layers or intercalations of terrigenious clastic and carbonate components. On the basis of the research on a lot of materials and study on the lower Cretaceous mixed sedimentary reservoir in Qingxi depression of Jiuquan Basin, using methods such as thin-section observation, field-emission scanning electron microscope observation, bulk minerals and clay minerals analysis, mercury injection test and nano-CT, analysis on lithologic associations and reservoir characteristics has been carried out on the mixed sedimentary reservoir. Macroscopically, the mixed sedimentary rock is lithologically complex, composed of dolomitic mudstone, argillaceous dolomite, lime mudstone, lime dolomite and dolomitic limestone, and so on, and presenting three types of vertical profile associations as great suites of thick layers, thick layers intercalated with thin layers and interbedded layers of similar thickness. Microscopically, clay minerals, carbonate minerals and organic matters present laminated or massive distribution form. The mixed sedimentary reservoir develops micro-nanometer scale interparticle pores, intraparticle pores and microfractures. The composition and content of minerals are one of the main factors affecting reservoir space types. Most mixed sedimentary reservoir has low permeability and low porosity, being regarded as tight reservoir.
Mixed sedimentary rock is referred to the rock composed of terrigenous clastics and carbonate components under mixed sedimentation. In a broad sense, it also includes the spatially alternating layers or intercalations of terrigenious clastic and carbonate components. On the basis of the research on a lot of materials and study on the lower Cretaceous mixed sedimentary reservoir in Qingxi depression of Jiuquan Basin, using methods such as thin-section observation, field-emission scanning electron microscope observation, bulk minerals and clay minerals analysis, mercury injection test and nano-CT, analysis on lithologic associations and reservoir characteristics has been carried out on the mixed sedimentary reservoir. Macroscopically, the mixed sedimentary rock is lithologically complex, composed of dolomitic mudstone, argillaceous dolomite, lime mudstone, lime dolomite and dolomitic limestone, and so on, and presenting three types of vertical profile associations as great suites of thick layers, thick layers intercalated with thin layers and interbedded layers of similar thickness. Microscopically, clay minerals, carbonate minerals and organic matters present laminated or massive distribution form. The mixed sedimentary reservoir develops micro-nanometer scale interparticle pores, intraparticle pores and microfractures. The composition and content of minerals are one of the main factors affecting reservoir space types. Most mixed sedimentary reservoir has low permeability and low porosity, being regarded as tight reservoir.
2015, 33(2): 394-407.
doi: 10.14027/j.cnki.cjxb.2015.02.019
Abstract:
On the basis of thin section, casting thin sections, X-diffration and scanning electron microscope data, this article discusses reservoir properties including lithology, physical property and reservoir space of the Cretaceous Bashijiqike Formation in Dabei area of the Kuqa Depression. Combining with Elemental Capture Spectroscopy (ECS) logging, diagenesis and characteristics of diagenetic mineral assembladges were studied. The difference of diagenesis between Ba 2 (the second member of Bashijiqike Formation) transgressive system tract and Ba 1 highstand system tract is also analyzed. The results show that corrosion phenomena are widely observed in the thin sections, with the decrease of feldspathic litharenite content near the boundary and improvement of physical property near sequence boundary. The clay content is higher both at the maximum flooding surfaces due to deposition, and under the sequence boundaries due to kaolinization after corrosion. On the whole, the controls of sequence boundaries and system tracts on carbonate cementation are not obvious. Different contents of carbonate cement could be seen in every part of sequence, which are related to alkaline diagenetic environment of the study area. Study results are beneficial for the track and comparison of reservoirs; Moreover, these would direct the exploration of gas and promote the development of the sequence stratigraphy theory.
On the basis of thin section, casting thin sections, X-diffration and scanning electron microscope data, this article discusses reservoir properties including lithology, physical property and reservoir space of the Cretaceous Bashijiqike Formation in Dabei area of the Kuqa Depression. Combining with Elemental Capture Spectroscopy (ECS) logging, diagenesis and characteristics of diagenetic mineral assembladges were studied. The difference of diagenesis between Ba 2 (the second member of Bashijiqike Formation) transgressive system tract and Ba 1 highstand system tract is also analyzed. The results show that corrosion phenomena are widely observed in the thin sections, with the decrease of feldspathic litharenite content near the boundary and improvement of physical property near sequence boundary. The clay content is higher both at the maximum flooding surfaces due to deposition, and under the sequence boundaries due to kaolinization after corrosion. On the whole, the controls of sequence boundaries and system tracts on carbonate cementation are not obvious. Different contents of carbonate cement could be seen in every part of sequence, which are related to alkaline diagenetic environment of the study area. Study results are beneficial for the track and comparison of reservoirs; Moreover, these would direct the exploration of gas and promote the development of the sequence stratigraphy theory.
2015, 33(2): 416-425.
doi: 10.14027/j.cnki.cjxb.2015.02.021
Abstract:
Crude oil samples of Honghe Oilfield in the Ordos Basin were collected systematically, and geochemical analyses were carried out, the hydrocarbon group composition and characteristics of biomarkers of crude oils were studied, on the basis of this research, the oil source were discussed at the same time. The research results show that the crude oils of Honghe Oilfield in the Mesozoic Ordos Basin have similar geochemical characteristics, reflects that they came from the same source. Their organic matters came from the mixed source of aquatic organism and higher plants, especially the higher plants made greater contribution to the oil generation. Crude oil formed in reduction to weak reduction and fresh or brackish water environment. Crude oils are all mature. The crude oils were mainly originated from the oil shale which located in the bottom of Chang-7 oil-bearing formation.
Crude oil samples of Honghe Oilfield in the Ordos Basin were collected systematically, and geochemical analyses were carried out, the hydrocarbon group composition and characteristics of biomarkers of crude oils were studied, on the basis of this research, the oil source were discussed at the same time. The research results show that the crude oils of Honghe Oilfield in the Mesozoic Ordos Basin have similar geochemical characteristics, reflects that they came from the same source. Their organic matters came from the mixed source of aquatic organism and higher plants, especially the higher plants made greater contribution to the oil generation. Crude oil formed in reduction to weak reduction and fresh or brackish water environment. Crude oils are all mature. The crude oils were mainly originated from the oil shale which located in the bottom of Chang-7 oil-bearing formation.
2015, 33(2): 226-231.
doi: 10.14027/j.cnki.cjxb.2015.02.002
Abstract:
Based on the outcrop measurement and indoor identification to the Luoreping Formation in southern Micangshan,it has been found that there are many tempestites in the Luoreping Formation of Middle Silurian in southern Micangshan, developing ditch structures, gravel-sized grain structures and graded bedding. The main lithology are mud shale, micrite and bioclastic limestone. There are three kinds of sedimentary sequences in the tempestites which show a certain inheritance. This is distal storm deposit and shallow shelf sedimentary environment. The discovery of storm-induced rocks in the area has explained the causes of the biological limestone lenticle, providing new standard for regional stratigraphic isochronous correlation and basis for the evolution of ancient geography, climate and Yangtze basin development. This study indicates that the later Luoreping Group sedimentation period in Nanjiang area has been in low latitude areas where storms frequently take place.
Based on the outcrop measurement and indoor identification to the Luoreping Formation in southern Micangshan,it has been found that there are many tempestites in the Luoreping Formation of Middle Silurian in southern Micangshan, developing ditch structures, gravel-sized grain structures and graded bedding. The main lithology are mud shale, micrite and bioclastic limestone. There are three kinds of sedimentary sequences in the tempestites which show a certain inheritance. This is distal storm deposit and shallow shelf sedimentary environment. The discovery of storm-induced rocks in the area has explained the causes of the biological limestone lenticle, providing new standard for regional stratigraphic isochronous correlation and basis for the evolution of ancient geography, climate and Yangtze basin development. This study indicates that the later Luoreping Group sedimentation period in Nanjiang area has been in low latitude areas where storms frequently take place.
2015, 33(2): 242-253.
doi: 10.14027/j.cnki.cjxb.2015.02.004
Abstract:
The saline sediments' characteristics of member 4 of Funing Formation of Paleogene (E1f4) in Zhaoji sag of Hongze depression, North Jiangsu Basin were studied by means of mud logging, well logging, paleontological and geochemical data, in order to find out the origin of saline sediments of E1f4 in Zhaoji sag, Hongze depression. It's found that the E1f4 saline formation mainly develops halilyte, sulfate rock, and a small amount of carbonate rock, and saline mineral layers are relatively thick, pure and distribute steadily on the lateral direction. Through comparisons, it's proposed that much saline substance of Pukou Formation of Late Cretaceous (K2p) in Huaian Uplift was dissolved and transported into the deep water of Zhaoji Sag, and then made the saline substance reach saturation, finally resedimented to form the saline formation of E1f4. Compared with the saline sediments of K2p in Huaian Uplift, salt rocks of E1f4 in Zhaoji Sag are much purer and cleaner, and inter-salt rocks are mainly gray-dark or gray mudstone, and moreover, shallow water evaporation structures have not been discovered; ostracoda fossil is dominated among the aquatic fossil, but gastropod and charophyta fossils living in shallow water are poor, furthermore, the Cicat ricosisporites pseudoanrifer, Welwitschiapitesningensis and Cicatricosisporites pseudoaurifer fossils only existing in the K2p Formation show in the E1f Formation; the type of brine of the two places is sulphate-chloride type, but the content of heavy metal elements of E1f4 in Zhaoji sag is much less than that of K2p in Huaian Uplift. The salt-forming period of E1f4 in Zhaoji sag can be divided into two stages: the Upper Salt Bed Sub-member and the Lower Salt Bed Sub-member. Through comparative study on the Upper Salt Bed Sub-member and the Lower Salt Bed Sub-member, it is found that there is a big difference on the types and characteristics of the saline sediment and sedimentary sequences, therefore, the salt-forming models could be tried to establish according to the differences in the rate and composition of salt supplies. The salt-forming model of the Upper Salt Bed Sub-member is "the resedimented model :Halite-Thenardite-Halite" in the saline substance supplied quickly, near source and deep water sedimentary environment; and the Lower Salt Bed Sub-member is "the resedimented model: Glauberite-Halite" in the saline substance supplied slowly, near source and deep water sedimentary environment.
The saline sediments' characteristics of member 4 of Funing Formation of Paleogene (E1f4) in Zhaoji sag of Hongze depression, North Jiangsu Basin were studied by means of mud logging, well logging, paleontological and geochemical data, in order to find out the origin of saline sediments of E1f4 in Zhaoji sag, Hongze depression. It's found that the E1f4 saline formation mainly develops halilyte, sulfate rock, and a small amount of carbonate rock, and saline mineral layers are relatively thick, pure and distribute steadily on the lateral direction. Through comparisons, it's proposed that much saline substance of Pukou Formation of Late Cretaceous (K2p) in Huaian Uplift was dissolved and transported into the deep water of Zhaoji Sag, and then made the saline substance reach saturation, finally resedimented to form the saline formation of E1f4. Compared with the saline sediments of K2p in Huaian Uplift, salt rocks of E1f4 in Zhaoji Sag are much purer and cleaner, and inter-salt rocks are mainly gray-dark or gray mudstone, and moreover, shallow water evaporation structures have not been discovered; ostracoda fossil is dominated among the aquatic fossil, but gastropod and charophyta fossils living in shallow water are poor, furthermore, the Cicat ricosisporites pseudoanrifer, Welwitschiapitesningensis and Cicatricosisporites pseudoaurifer fossils only existing in the K2p Formation show in the E1f Formation; the type of brine of the two places is sulphate-chloride type, but the content of heavy metal elements of E1f4 in Zhaoji sag is much less than that of K2p in Huaian Uplift. The salt-forming period of E1f4 in Zhaoji sag can be divided into two stages: the Upper Salt Bed Sub-member and the Lower Salt Bed Sub-member. Through comparative study on the Upper Salt Bed Sub-member and the Lower Salt Bed Sub-member, it is found that there is a big difference on the types and characteristics of the saline sediment and sedimentary sequences, therefore, the salt-forming models could be tried to establish according to the differences in the rate and composition of salt supplies. The salt-forming model of the Upper Salt Bed Sub-member is "the resedimented model :Halite-Thenardite-Halite" in the saline substance supplied quickly, near source and deep water sedimentary environment; and the Lower Salt Bed Sub-member is "the resedimented model: Glauberite-Halite" in the saline substance supplied slowly, near source and deep water sedimentary environment.
2015, 33(2): 265-274.
doi: 10.14027/j.cnki.cjxb.2015.02.006
Abstract:
The comparative study of the Mesozoic marine carbonate stratum has limited to paleostratigraphy in the Qiangtang depression of Tibet. Based on the strontium isotope stratigraphy, this paper was made correlation to the globe of the upper Jurassic-lower Cretaceous in Suowa Formation. On the basis of the analyzed the rock fabric, cathodeluminescence, chemical composition and preservative evaluation for coeval seawater information, this paper measured strontium isotopic composition of the samples and constructed the evolution curve. Results show that, these data of the samples are generally coincident with 87Sr/86Sr ratios of coeval seawater from previous papers, and the curve is also similar to other previous curves, this indicates that the global sea level change and erosion intensity are the most important controlling factors to the strontium isotope evolution in the upper Jurassic-lower Cretaceous. In addition, we consider that the upper of Suowa Formation maybe extend to Hauterivian in the early Cretaceous through the study of strontium isotope, this suggests that there exist large-scale marine stratigraphy at the same of Hauterivian in the early Cretaceous, Qiangtang Depression.
The comparative study of the Mesozoic marine carbonate stratum has limited to paleostratigraphy in the Qiangtang depression of Tibet. Based on the strontium isotope stratigraphy, this paper was made correlation to the globe of the upper Jurassic-lower Cretaceous in Suowa Formation. On the basis of the analyzed the rock fabric, cathodeluminescence, chemical composition and preservative evaluation for coeval seawater information, this paper measured strontium isotopic composition of the samples and constructed the evolution curve. Results show that, these data of the samples are generally coincident with 87Sr/86Sr ratios of coeval seawater from previous papers, and the curve is also similar to other previous curves, this indicates that the global sea level change and erosion intensity are the most important controlling factors to the strontium isotope evolution in the upper Jurassic-lower Cretaceous. In addition, we consider that the upper of Suowa Formation maybe extend to Hauterivian in the early Cretaceous through the study of strontium isotope, this suggests that there exist large-scale marine stratigraphy at the same of Hauterivian in the early Cretaceous, Qiangtang Depression.
2015, 33(2): 285-298.
doi: 10.14027/j.cnki.cjxb.2015.02.008
Abstract:
The Quaternary red earth is widespread in the present Yangtze River Valley. Like the Loess-palesol sequences in north of China, the red earth provides detailed records of Quaternary environmental and climatic change. The typical red earth profiles usually consists of homogenous red earth range in the upper part and reticular red earth horizons in the lower part. In this study, we have investigated magnetic properties and particle-size distribution of two red earth sections (CS and HN) at Hunan Province, two sections (NC and XY) at Jiangxi Province, and a section (GC) at Zhejiang Province, with the purpose to investigate the feasibility of magnetic properties in paleo-climate reconstruction. The results suggest:1) The Quaternary red earth in CS , HN, NC and GC, located in the transitional zone between red earth and Xiashu loess, was aeolian origin, as it shared many aeolian features with Xiashu loess and Chinese North loess; however, the Quaternary red clay in Xinyu is significantly different from the other four areas in particle-size composition. It often has gravels and a relatively high content of sands, demonstrating diluvial or alluvial properties.2) Multiple magnetic parameters show that maghemite, hematite and goethite of pedogenic origin make dominant contributions to the enhanced magnetic susceptibility of the red earth.3) The relative content of these minerals are various in different regions and different weathering stages. However, magnetic susceptibility and S-ratio declines while Hard Isothermal Remanent Magnetization (HIRM) increases significantly in the lower strongly weathering reticulate red clay layer, which results from the enrichment of antiferromagnetic minerals and the dissollution of the maghemite. Therefore, we conclude that the anomalous decrease of the magnetic susceptibility is the result of the reducing action, which might be the production within a period of enhanced precipitation.4) Magnetic characteristics of Xinyu far different from other four sections may be a reason that material source is not identical with other four dust caused clay. Further work is needed to provide more evidence.
The Quaternary red earth is widespread in the present Yangtze River Valley. Like the Loess-palesol sequences in north of China, the red earth provides detailed records of Quaternary environmental and climatic change. The typical red earth profiles usually consists of homogenous red earth range in the upper part and reticular red earth horizons in the lower part. In this study, we have investigated magnetic properties and particle-size distribution of two red earth sections (CS and HN) at Hunan Province, two sections (NC and XY) at Jiangxi Province, and a section (GC) at Zhejiang Province, with the purpose to investigate the feasibility of magnetic properties in paleo-climate reconstruction. The results suggest:1) The Quaternary red earth in CS , HN, NC and GC, located in the transitional zone between red earth and Xiashu loess, was aeolian origin, as it shared many aeolian features with Xiashu loess and Chinese North loess; however, the Quaternary red clay in Xinyu is significantly different from the other four areas in particle-size composition. It often has gravels and a relatively high content of sands, demonstrating diluvial or alluvial properties.2) Multiple magnetic parameters show that maghemite, hematite and goethite of pedogenic origin make dominant contributions to the enhanced magnetic susceptibility of the red earth.3) The relative content of these minerals are various in different regions and different weathering stages. However, magnetic susceptibility and S-ratio declines while Hard Isothermal Remanent Magnetization (HIRM) increases significantly in the lower strongly weathering reticulate red clay layer, which results from the enrichment of antiferromagnetic minerals and the dissollution of the maghemite. Therefore, we conclude that the anomalous decrease of the magnetic susceptibility is the result of the reducing action, which might be the production within a period of enhanced precipitation.4) Magnetic characteristics of Xinyu far different from other four sections may be a reason that material source is not identical with other four dust caused clay. Further work is needed to provide more evidence.
2015, 33(2): 306-313.
doi: 10.14027/j.cnki.cjxb.2015.02.010
Abstract:
Characteristics of the sedimentary evolution in the progress of transformation from ocean to continent determines the genetic type, distribution, and classified evaluation of gas reservoir in Upper Paleozoic of Daniudi Gasfield, Ordos Basin. Analysis of core observation, in combination with logging, seismic data of Taiyuan-Shanxi-Xiashihezi Formations, resulted that carbonate ramp in lower part and barrier-lagoon-tidal flat system in the upper part of the Taiyuan Formation in a shore environment; the Shanxi Formation is a tidal dominated braided delta system in the background of transition environment; and the Xiashihezi Formation is a fluvial system as the continually north uplift and continental clastic significantly advance to the study area; the whole Upper Paleozoic shows a continued progress of progradation. In the change from sea to land environment, coals of the Taiyuan and Shanxi Formations are main hydrocarbon resources in the study area; sand bodies of the barrier bar, tidal channel of Taiyuan Formation, the braided and tidal channel and tidal sand flat of Shanxi Formation, and the stacking braided-meandering channel of Xiashihezi Formation are favorable reservoir in Upper Paleozoic.
Characteristics of the sedimentary evolution in the progress of transformation from ocean to continent determines the genetic type, distribution, and classified evaluation of gas reservoir in Upper Paleozoic of Daniudi Gasfield, Ordos Basin. Analysis of core observation, in combination with logging, seismic data of Taiyuan-Shanxi-Xiashihezi Formations, resulted that carbonate ramp in lower part and barrier-lagoon-tidal flat system in the upper part of the Taiyuan Formation in a shore environment; the Shanxi Formation is a tidal dominated braided delta system in the background of transition environment; and the Xiashihezi Formation is a fluvial system as the continually north uplift and continental clastic significantly advance to the study area; the whole Upper Paleozoic shows a continued progress of progradation. In the change from sea to land environment, coals of the Taiyuan and Shanxi Formations are main hydrocarbon resources in the study area; sand bodies of the barrier bar, tidal channel of Taiyuan Formation, the braided and tidal channel and tidal sand flat of Shanxi Formation, and the stacking braided-meandering channel of Xiashihezi Formation are favorable reservoir in Upper Paleozoic.
2015, 33(2): 326-336.
doi: 10.14027/j.cnki.cjxb.2015.02.012
Abstract:
High-resolution sequence stratigraphic theories and the architecture analysis method are synthetically applied to study controls of long-term base-level cycles on architecture of mouth bars by taking the lower Es2 Member in Fault-Block Tuo 7, Shengtuo oilfield as a case study. The results show that the bottom of Es2 Member of Tuo 7 Fault-Block in Shengtuo oilfield constitutes a long-term base-level decreasing semi-cycle which can be subdivided into 8 middle-term cycles, some short-term cycles and various super short-term cycles. During long-term base-level fall, continuity of mouth bars become better, scale of distributary channels on the bars become larger and extending distance of these channels become longer; At the early stage of long-term base-level fall, combination patterns between different mouth bars in the same period are mainly by means of one mouth bar's fringe staggers on the another or mouth bars are separated by inter bar mudstone, At the late stage of long-term base-level fall, combinations between different mouth bars in the same period are mainly by means of one bar's main part overlaps another bar's fringe or one bar's fringe overlaps another's; Meanwhile, during long-term base-level fall, mouth bars' vertical connectivity become better and dip angles become smaller. Long-term base-level cycle controls mouth bars' architecture mainly through regular change of accommodation and supply rate of sediments. This study has a potentially important significance in guiding prediction of sandstones and remaining oil's distribution in this type of oil and gas fields.
High-resolution sequence stratigraphic theories and the architecture analysis method are synthetically applied to study controls of long-term base-level cycles on architecture of mouth bars by taking the lower Es2 Member in Fault-Block Tuo 7, Shengtuo oilfield as a case study. The results show that the bottom of Es2 Member of Tuo 7 Fault-Block in Shengtuo oilfield constitutes a long-term base-level decreasing semi-cycle which can be subdivided into 8 middle-term cycles, some short-term cycles and various super short-term cycles. During long-term base-level fall, continuity of mouth bars become better, scale of distributary channels on the bars become larger and extending distance of these channels become longer; At the early stage of long-term base-level fall, combination patterns between different mouth bars in the same period are mainly by means of one mouth bar's fringe staggers on the another or mouth bars are separated by inter bar mudstone, At the late stage of long-term base-level fall, combinations between different mouth bars in the same period are mainly by means of one bar's main part overlaps another bar's fringe or one bar's fringe overlaps another's; Meanwhile, during long-term base-level fall, mouth bars' vertical connectivity become better and dip angles become smaller. Long-term base-level cycle controls mouth bars' architecture mainly through regular change of accommodation and supply rate of sediments. This study has a potentially important significance in guiding prediction of sandstones and remaining oil's distribution in this type of oil and gas fields.
2015, 33(2): 348-356.
doi: 10.14027/j.cnki.cjxb.2015.02.014
Abstract:
Lacustrine palaeoshore line is the intersection position between the lake level and the ancient land in geologic time, and the boundary between the onshore deposits and the subaqueous deposits. Determining the location of lacustrine palaeoshore line has important guide on exploration of oil and gas. In this paper, by the means of conventional mudstone color, mudstone X-ray diffraction analysis, GR curve characteristics, and organic petrology analysis, the location and swing area of lacustrine palaeoshore line of He 8 has been studied. The lacustrine palaeoshore line in the sedimentary basin controls the formation and development of the high quality reservoir. The physical properties of sandstones from sedimentary belt above water are better than those from shoreline swing band and underwater sedimentary belt sandstones because of the difference of sandstone size, soft lithoclast content, composition of interstitial material and diagenesis.
Lacustrine palaeoshore line is the intersection position between the lake level and the ancient land in geologic time, and the boundary between the onshore deposits and the subaqueous deposits. Determining the location of lacustrine palaeoshore line has important guide on exploration of oil and gas. In this paper, by the means of conventional mudstone color, mudstone X-ray diffraction analysis, GR curve characteristics, and organic petrology analysis, the location and swing area of lacustrine palaeoshore line of He 8 has been studied. The lacustrine palaeoshore line in the sedimentary basin controls the formation and development of the high quality reservoir. The physical properties of sandstones from sedimentary belt above water are better than those from shoreline swing band and underwater sedimentary belt sandstones because of the difference of sandstone size, soft lithoclast content, composition of interstitial material and diagenesis.
2015, 33(2): 364-375.
doi: 10.14027/j.cnki.cjxb.2015.02.016
Abstract:
Marine deposits in Shahejie Formation of Dongpu Depression whether it is true or not remains a question. However, Ichnology integrated with sedimentology and palaeontology could be a useful tool in solving this problem. In Well Kai 31, marine regression records indicated by flaser bedding (Well depth 3 553.30 m) followed by double clay drapes(3 552.70 m) and hummocky cross-bedding as well as plant roots(3 551.50 m) showing the environment from foreshore, shoreface shift to backshore. Another marine regression sequence existed in Well Xinhu 4 where marine trace fossils of Diplocraterion, Palaeophycos, Terebellina (2 969.10 m, 2 966.40 m) are also covered by plant roots(2 931.93 m) indicated the sea level fall. In contrast to marine regression records marine transgression sequence recorded by lenticular bedding, plant roots, horringbone cross bedding from Well Kai 34 are interpreted as foreshore environment. Trace fossils of Thalassinoides, Macaronichnus suggesting a shoreface environment occur. Strong bioturbated beds and body fossils of coccoliths are considered as offshore (shallow marine) environment. Studies show that the environment from backshore to offshore can be recognized by means of ichnology integrated with sedimentology and palaeontology in Dongpu Depression. Studies also show that the discoutinuous surface indicating by firm-ground substrate controlled ichnofacies associated with marine transgression sequence are helpful in forming discordant trap.
Marine deposits in Shahejie Formation of Dongpu Depression whether it is true or not remains a question. However, Ichnology integrated with sedimentology and palaeontology could be a useful tool in solving this problem. In Well Kai 31, marine regression records indicated by flaser bedding (Well depth 3 553.30 m) followed by double clay drapes(3 552.70 m) and hummocky cross-bedding as well as plant roots(3 551.50 m) showing the environment from foreshore, shoreface shift to backshore. Another marine regression sequence existed in Well Xinhu 4 where marine trace fossils of Diplocraterion, Palaeophycos, Terebellina (2 969.10 m, 2 966.40 m) are also covered by plant roots(2 931.93 m) indicated the sea level fall. In contrast to marine regression records marine transgression sequence recorded by lenticular bedding, plant roots, horringbone cross bedding from Well Kai 34 are interpreted as foreshore environment. Trace fossils of Thalassinoides, Macaronichnus suggesting a shoreface environment occur. Strong bioturbated beds and body fossils of coccoliths are considered as offshore (shallow marine) environment. Studies show that the environment from backshore to offshore can be recognized by means of ichnology integrated with sedimentology and palaeontology in Dongpu Depression. Studies also show that the discoutinuous surface indicating by firm-ground substrate controlled ichnofacies associated with marine transgression sequence are helpful in forming discordant trap.
2015, 33(2): 385-393.
doi: 10.14027/j.cnki.cjxb.2015.02.018
Abstract:
In order to find the favorable exploration target, based on cores observation and sediment, structural analysis, the application of 3D seismic data, drilling well data and well-logging data, the detailed research has been carried out. Lacustrine mudstones extensively developed in Qingshankou Formation of the northern Songliao Basin. The mainly sedimentary facies include delta plain, the deltaic front, outside the deltaic front and lacustrine sediments. Based on 3D seismic data, drilling core observation, well logs and other data, large-scale gravity flow deposits were found in the study area. Sliding rock, rock slump, debris flow, turbid flow are four types of gravity flow in the Qingshankou Formation lacustrine facies area. This article studied the petrography of gravity flow, particle deposition characteristics, and the vertical distribution characteristics. Through the study on the lower part of theⅡmember of Qingshankou Formation, it was found that the main rock types are slumping rock and slide rock. Main lithologies are thin interbedded, silt sandstone, argillaceous sandstone, and silty mudstone. Some regions contained few oil or oil stains. Main lithologies are thin interbedded, silty mudstone, coarse sandstone, mudstone, siltstone and mudstone, at the top of Qingshankou Formation deposits are debris flow and turbidite flow deposition. It acts as a guiding role for further exploration in Songliao Basin with development and control mechanisms of gravity flow. Through analysis by single well cores, logging curves, distribution characteristics, developmental horizontal of gravity flow were described in Ⅰ,ⅡMembers of Qingshankou Formation, this study sets a guide for in-depth understanding of lacustrine sediments. Exploration of gravity flow deposits in the Songliao Basin is still in the exploratory stage, its significance lies in looking for new favorable exploration sites, and found a solid foundation for research on deep water sedimentary gravity flow studies in large continental basin.
In order to find the favorable exploration target, based on cores observation and sediment, structural analysis, the application of 3D seismic data, drilling well data and well-logging data, the detailed research has been carried out. Lacustrine mudstones extensively developed in Qingshankou Formation of the northern Songliao Basin. The mainly sedimentary facies include delta plain, the deltaic front, outside the deltaic front and lacustrine sediments. Based on 3D seismic data, drilling core observation, well logs and other data, large-scale gravity flow deposits were found in the study area. Sliding rock, rock slump, debris flow, turbid flow are four types of gravity flow in the Qingshankou Formation lacustrine facies area. This article studied the petrography of gravity flow, particle deposition characteristics, and the vertical distribution characteristics. Through the study on the lower part of theⅡmember of Qingshankou Formation, it was found that the main rock types are slumping rock and slide rock. Main lithologies are thin interbedded, silt sandstone, argillaceous sandstone, and silty mudstone. Some regions contained few oil or oil stains. Main lithologies are thin interbedded, silty mudstone, coarse sandstone, mudstone, siltstone and mudstone, at the top of Qingshankou Formation deposits are debris flow and turbidite flow deposition. It acts as a guiding role for further exploration in Songliao Basin with development and control mechanisms of gravity flow. Through analysis by single well cores, logging curves, distribution characteristics, developmental horizontal of gravity flow were described in Ⅰ,ⅡMembers of Qingshankou Formation, this study sets a guide for in-depth understanding of lacustrine sediments. Exploration of gravity flow deposits in the Songliao Basin is still in the exploratory stage, its significance lies in looking for new favorable exploration sites, and found a solid foundation for research on deep water sedimentary gravity flow studies in large continental basin.
2015, 33(2): 408-415.
doi: 10.14027/j.cnki.cjxb.2015.02.020
Abstract:
Reef-bank dolomite is one of the most promising oil and gas reservoir types. Although the foundation of developing reef-bank dolomite type reservoir existed, the research of its characterization and distribution is fairly poor. In this paper, by using the methods of outcrop observation, single well data analysis, seismic data characterization, we identified the Lower Cambrian platform margin in Keping-western Tabei area, which was named as the northern platform margin. With the scale of 330 km length and 7km width, it extends as NE-trending. Outcrop data shows that the Lower Cambrian northern platform margin developed two periods of microbial reef, with the main lithology of pinhole dolomite developing dissolution pores. A group of seismic reflection units with mounded geometry can be seen in the seismic section clearly. The Northern platform margin located in the long-term developed ancient inherited uplift has a unique reservoir-cap configuration advantage, which makes it have the favorable conditions to form a large oil and gas field. The distribution of the northern platform margin has made clear the direction of play evaluation and target optimization in the Lower Paleozoic dolomite area.
Reef-bank dolomite is one of the most promising oil and gas reservoir types. Although the foundation of developing reef-bank dolomite type reservoir existed, the research of its characterization and distribution is fairly poor. In this paper, by using the methods of outcrop observation, single well data analysis, seismic data characterization, we identified the Lower Cambrian platform margin in Keping-western Tabei area, which was named as the northern platform margin. With the scale of 330 km length and 7km width, it extends as NE-trending. Outcrop data shows that the Lower Cambrian northern platform margin developed two periods of microbial reef, with the main lithology of pinhole dolomite developing dissolution pores. A group of seismic reflection units with mounded geometry can be seen in the seismic section clearly. The Northern platform margin located in the long-term developed ancient inherited uplift has a unique reservoir-cap configuration advantage, which makes it have the favorable conditions to form a large oil and gas field. The distribution of the northern platform margin has made clear the direction of play evaluation and target optimization in the Lower Paleozoic dolomite area.
