2003 Vol. 21, No. 4
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Display Method:
2003, 21(4): 539-546.
Abstract:
Sedimentary facies of tidal flat indicate that coastal environment is characterized by gentle coastal slope, predominant tidal dy namics, and with plenty of fine grain (silt)sediment supply.The comparative study of sedimentary facies has shown high level agreement betw een present tidal flat and ancient fine tex tural sedimentary rocks of the middle Triassic Huangmaqing Formation in Purple Mountain of Nanjing, and Zhanjiang Formation of early Pleistocene Period in Haikou.Besides the similarity in nature of grain size probabili ty diag ram, palosalinity and Brackish paleontology group among the three sedimentary series, the major character of the rocks is the Zonation features with typical structures as rhy thmic thick-thin laminal of silty and clayey sediments, with ripples, herring bone shaped or dune-shaped cross beddings in the lower sandy sections, and polygon structures or desiccated clay cracks, clay pebbles, worm tubes or calcic concretions in the upper muddy sections.These series of sedimentary facies reflect a lower energy environment of land-sea interaction along coastal shallow sea.
Sedimentary facies of tidal flat indicate that coastal environment is characterized by gentle coastal slope, predominant tidal dy namics, and with plenty of fine grain (silt)sediment supply.The comparative study of sedimentary facies has shown high level agreement betw een present tidal flat and ancient fine tex tural sedimentary rocks of the middle Triassic Huangmaqing Formation in Purple Mountain of Nanjing, and Zhanjiang Formation of early Pleistocene Period in Haikou.Besides the similarity in nature of grain size probabili ty diag ram, palosalinity and Brackish paleontology group among the three sedimentary series, the major character of the rocks is the Zonation features with typical structures as rhy thmic thick-thin laminal of silty and clayey sediments, with ripples, herring bone shaped or dune-shaped cross beddings in the lower sandy sections, and polygon structures or desiccated clay cracks, clay pebbles, worm tubes or calcic concretions in the upper muddy sections.These series of sedimentary facies reflect a lower energy environment of land-sea interaction along coastal shallow sea.
2003, 21(4): 560-564.
Abstract:
Lower Cretaceous muddy dolostone distributed Qingxi sag, Jiuxi depression is characterized by the high content of special mineral assemblage including clay-sized albite and quartz, ankerite and barite, and so on.So far, there have been different debates on the origin of this special rock type, resulting in the difficult evaluation on the muddy dolostone reservoir.Based on the systematic structural, depositional and petrologic study on this kind of rock, this paper has pointed out that the rock is closely related to the overflow of thermal water from lake bottom, and, furthermore, discusses the role of the special rock in controlling petroleum formation as well as the future exploration direction.
Lower Cretaceous muddy dolostone distributed Qingxi sag, Jiuxi depression is characterized by the high content of special mineral assemblage including clay-sized albite and quartz, ankerite and barite, and so on.So far, there have been different debates on the origin of this special rock type, resulting in the difficult evaluation on the muddy dolostone reservoir.Based on the systematic structural, depositional and petrologic study on this kind of rock, this paper has pointed out that the rock is closely related to the overflow of thermal water from lake bottom, and, furthermore, discusses the role of the special rock in controlling petroleum formation as well as the future exploration direction.
2003, 21(4): 571-578.
Abstract:
The air heave structure is a sedimentary phenomenon that is seldom observed, however, it is so well developed in the modern Yellow River delta that we may even find it on the riverbeds of the plains higher than the level of the water surface as well as many other minor sedimentary facies.They are very attractive for their unique looks and their finished configurations;w hat's more, they can show up in a large scale and present us a splendid sight in some reaches of the river. Most of the air heave structures developed in the Yellow River often show us as a circular dome in the shape,the rest as a plate;the diameter of them vary from scores of centimeters to one or two meters;as to those of plateshaped, the diameter of them can amount to scores of meters in the length as well as the width, and from several centimeters to twenties or thirties centimeters in the height. As to the configuration of the air heave structure, it was made up of three parts:the cover, the room and the base.The depth of its cover is f rom >10 centimeters to >20 centimeters.Some of the covers are smooth and some are sprinkled with arch cracks, imploded cracks, concentric quoits, eroded pits and slots, ripple marks, whiffing mud-sand volcanoes, slip and crimple squamas, air-discharging holes(pits, slot)and other accompanying or secondary structures such as some rill marks, and so on. The genesis of the air heave structures developed in the Yellow River is rather complex.By study ing the cause, we must relate it w ith the unique hy drology and the hydromechanical conditions fo rmed by the cut-off of the Yellow River and the co rrespondingly typical st ructure of the riverbed and the g ranule(clay and f ine siltite)characteristics of the sediments in the Yellow River.
The air heave structure is a sedimentary phenomenon that is seldom observed, however, it is so well developed in the modern Yellow River delta that we may even find it on the riverbeds of the plains higher than the level of the water surface as well as many other minor sedimentary facies.They are very attractive for their unique looks and their finished configurations;w hat's more, they can show up in a large scale and present us a splendid sight in some reaches of the river. Most of the air heave structures developed in the Yellow River often show us as a circular dome in the shape,the rest as a plate;the diameter of them vary from scores of centimeters to one or two meters;as to those of plateshaped, the diameter of them can amount to scores of meters in the length as well as the width, and from several centimeters to twenties or thirties centimeters in the height. As to the configuration of the air heave structure, it was made up of three parts:the cover, the room and the base.The depth of its cover is f rom >10 centimeters to >20 centimeters.Some of the covers are smooth and some are sprinkled with arch cracks, imploded cracks, concentric quoits, eroded pits and slots, ripple marks, whiffing mud-sand volcanoes, slip and crimple squamas, air-discharging holes(pits, slot)and other accompanying or secondary structures such as some rill marks, and so on. The genesis of the air heave structures developed in the Yellow River is rather complex.By study ing the cause, we must relate it w ith the unique hy drology and the hydromechanical conditions fo rmed by the cut-off of the Yellow River and the co rrespondingly typical st ructure of the riverbed and the g ranule(clay and f ine siltite)characteristics of the sediments in the Yellow River.
2003, 21(4): 601-606.
Abstract:
In order to increase the exploration level of hidden oil & gas pools in the area around Puwei sag,Dongpu depression, sequence stratigraphy theory and the Walther' s law are taken as a guide to research Sha-3 member.On the basis of the analy ses of cores, logs and seismic data, combined with the analyses of basin structure and stratigraphy, 5 depositional systems are recognized in Sha-3 member, i.e.lake-turbidite fan system, coast & shallow lake system with sand dam and tempestite, low-stand salt lake system, delta system and deep &hemi-deep lake system.The characteristics of lithoface assemblages of each system are studied one by one.The dist ribution patterns of the depositional systems in space are analysed in each main reservoir body member, while the sedimentary models and reservoir distribution regulations of the Sha-3 member are also discussed.It is pointed out that the junctions of the under water channels and the slope break belt in the east and north of Puwei sag are the places where the main reservoir bodies develop very well, and where lake-turbidite fan system and delta system develop.
In order to increase the exploration level of hidden oil & gas pools in the area around Puwei sag,Dongpu depression, sequence stratigraphy theory and the Walther' s law are taken as a guide to research Sha-3 member.On the basis of the analy ses of cores, logs and seismic data, combined with the analyses of basin structure and stratigraphy, 5 depositional systems are recognized in Sha-3 member, i.e.lake-turbidite fan system, coast & shallow lake system with sand dam and tempestite, low-stand salt lake system, delta system and deep &hemi-deep lake system.The characteristics of lithoface assemblages of each system are studied one by one.The dist ribution patterns of the depositional systems in space are analysed in each main reservoir body member, while the sedimentary models and reservoir distribution regulations of the Sha-3 member are also discussed.It is pointed out that the junctions of the under water channels and the slope break belt in the east and north of Puwei sag are the places where the main reservoir bodies develop very well, and where lake-turbidite fan system and delta system develop.
2003, 21(4): 615-619.
Abstract:
The shift of onlap-of flap points is a critical factor in sequence stratigraphic analysis and charting sea level curves.Onlap-off lap points, however, are easily removed due to tectonic uplift, eustatic sea level fall, and so on.How to recover the original positions of removed onlap and of flap points has still been a pending problem.In this paper, we presented a piecew ise-const ructed function model to depict the lateral changes of stratal thickness along a dip section.It is assumed that the thickness of a stratum decreases exponentially from its maximum tow ards basin margin, and thins linearly on areas adjacent to the onlap-offlap points.Using this model, the positions of removed onlap and of flap points can be extrapolated by fitting the thickness data in non-removal areas.This approach is used in the study of the Pliocene to Pleistocene strata on the no rthern Sunda Shelf, South China Sea, and the result sare to our satisfaction.
The shift of onlap-of flap points is a critical factor in sequence stratigraphic analysis and charting sea level curves.Onlap-off lap points, however, are easily removed due to tectonic uplift, eustatic sea level fall, and so on.How to recover the original positions of removed onlap and of flap points has still been a pending problem.In this paper, we presented a piecew ise-const ructed function model to depict the lateral changes of stratal thickness along a dip section.It is assumed that the thickness of a stratum decreases exponentially from its maximum tow ards basin margin, and thins linearly on areas adjacent to the onlap-offlap points.Using this model, the positions of removed onlap and of flap points can be extrapolated by fitting the thickness data in non-removal areas.This approach is used in the study of the Pliocene to Pleistocene strata on the no rthern Sunda Shelf, South China Sea, and the result sare to our satisfaction.
2003, 21(4): 627-633.
Abstract:
The Neoproterozoic Doushantou phodphorites in Weng' an, South China, preserved a unique assemblage of a most likely the earliest metazoan in the world.The reconst ruction of paleoenvironmental change, when the Weng' an metazoan fauna emerged, is most important.But REE diagenetic modification of the Doushantou phosphorites must be evaluated.This paper is to discuss the REE modification in the Weng' an phosphorites during post sedimentary stages by REE geochemistry of phosphatic and dolomitic cements, phosphatic clasts in the upper phosphorites, phosphorite and shale bands in the lower phosphorites. The later diagenetic mineral phases:dolomitic and phosphatic cements display similar North American Shale normalized REE patterns with associated authigenic phosphatic phases and suggest that the REE geochemical characteristics in the Doushantuo phosphorites could be taken as primary signatures of paleoseawater conditions and may imply that the REE in the authigenic phosphatic phases were not modified during their burial, digenesis and surface weathering.The different REE characteristics in the phosphatic bands and associated shale bands in couplet samples suggested that the REE digenetic reaction might be only taken place within -strata but not between strata.Negative correlation of ErN/LuN and positive correlation of LaN/NdN with Ce/Ce*suggests that the HREE and LREE depletions may derive from the change of paleoseawater redox condition, and HREE, LREE appear to be more depletion in the more oxidizing condition caused more Ce depletion.
The Neoproterozoic Doushantou phodphorites in Weng' an, South China, preserved a unique assemblage of a most likely the earliest metazoan in the world.The reconst ruction of paleoenvironmental change, when the Weng' an metazoan fauna emerged, is most important.But REE diagenetic modification of the Doushantou phosphorites must be evaluated.This paper is to discuss the REE modification in the Weng' an phosphorites during post sedimentary stages by REE geochemistry of phosphatic and dolomitic cements, phosphatic clasts in the upper phosphorites, phosphorite and shale bands in the lower phosphorites. The later diagenetic mineral phases:dolomitic and phosphatic cements display similar North American Shale normalized REE patterns with associated authigenic phosphatic phases and suggest that the REE geochemical characteristics in the Doushantuo phosphorites could be taken as primary signatures of paleoseawater conditions and may imply that the REE in the authigenic phosphatic phases were not modified during their burial, digenesis and surface weathering.The different REE characteristics in the phosphatic bands and associated shale bands in couplet samples suggested that the REE digenetic reaction might be only taken place within -strata but not between strata.Negative correlation of ErN/LuN and positive correlation of LaN/NdN with Ce/Ce*suggests that the HREE and LREE depletions may derive from the change of paleoseawater redox condition, and HREE, LREE appear to be more depletion in the more oxidizing condition caused more Ce depletion.
2003, 21(4): 640-647.
Abstract:
There are diffrent marks on depositional events which are caused by physical, chemical, or/and biological events in the sediment sequences.The suddenness on event deposits will contain various materials from different sources into sediment sequences.Terrest rial 4He abundance in the marine sediments is dominated by old continental dusts.Helium in seafloor sediments is predominantly derived from old continetal material with lower 3He/4He ratio.It is shown by the oretical calculationg that there is a considerable correlation between the bulk mass accumulation rates (MAR)of Asian Aeolian dust and 4He flux in the ocean basins.The onset of 100 kyr glacial-interglacial cycling in the oxygen isotope record clearly matches with the onset of 100 kyr periodicity in the crustal 4 He flux.Testing the IDP accretion rate by using extraterrest rial 3He flux in the samples from Ocean Drilling Program (ODP), It can be seen that the burial flux of extraterrest rial 3He is also associated with glacial-interglacial cycles. The fact that a high ex traterrestrial 3He ([ 3He] Et)found in the Cretaceous-Tertiary boundary (KTB)clay implies a short duration of the KTB event.The high 3He/4He ratios found in the fullerenes from Meishan (China) and Sasayama (Japan)should reveal that the fullerene carriers are formed in an extraterrest rial environment.In the cosmos, the difference of helium content and isotopic composition in various sources and the high helium preservation in the seafloor sediments may provide a high sensitivity means for exploring depositional events.
There are diffrent marks on depositional events which are caused by physical, chemical, or/and biological events in the sediment sequences.The suddenness on event deposits will contain various materials from different sources into sediment sequences.Terrest rial 4He abundance in the marine sediments is dominated by old continental dusts.Helium in seafloor sediments is predominantly derived from old continetal material with lower 3He/4He ratio.It is shown by the oretical calculationg that there is a considerable correlation between the bulk mass accumulation rates (MAR)of Asian Aeolian dust and 4He flux in the ocean basins.The onset of 100 kyr glacial-interglacial cycling in the oxygen isotope record clearly matches with the onset of 100 kyr periodicity in the crustal 4 He flux.Testing the IDP accretion rate by using extraterrest rial 3He flux in the samples from Ocean Drilling Program (ODP), It can be seen that the burial flux of extraterrest rial 3He is also associated with glacial-interglacial cycles. The fact that a high ex traterrestrial 3He ([ 3He] Et)found in the Cretaceous-Tertiary boundary (KTB)clay implies a short duration of the KTB event.The high 3He/4He ratios found in the fullerenes from Meishan (China) and Sasayama (Japan)should reveal that the fullerene carriers are formed in an extraterrest rial environment.In the cosmos, the difference of helium content and isotopic composition in various sources and the high helium preservation in the seafloor sediments may provide a high sensitivity means for exploring depositional events.
2003, 21(4): 654-662.
Abstract:
Through the comprehensive analysis of outcrops, cores, well logs and seismic interpretation data, and under the guidance of the theory and technology of the high-resolution sequence stratig raphy initiated by Timothy A-Cross in 1994, the characteristics of the different grade sequence interface and laucstrine flooding surface in the second member of Nadu Formation Eocene in Lun-35 Block of Ziyin Oil Field from Base Basin are studied.According to the identification sign of the sequence interface and flooding sedimentation, four-grade base-level cycle sequences that are divided into 13 ～ 18 supershort-term, 7 ～ 9 short-term, two middle-term, and one long-term cycle sequences are recognized from the formation.On the basis of these studies, the vertical sequence, facies association, lithologic component, structure type and stacking pattern are discussed in detail.Among these sequences, the supershort-term and short-term cycle sequence may be divided into two basic types of st ructure which are up-deepening non-symmetry and symmetry from up-deepening to up-shallowening.The first can be divided further into two subtypes of low or high accommodation and the second can be devided further into three subtypes of non-complete or nearly complete symmetry.These basic sequence types and subtypes are of various stacking and distribution patterns.The structure type and stacking pattern of the middle-term cycle sequence are the same as that of the shortterm cycle sequence.The long-term cycle sequence are of non-complete symmetric st ructure which develop complete depositional sequence of lacust rine transgressive-reg ressive cycle, and thickness of rising half-cycle is larger than the falling half-cycle.According to the high-resolution isochronous stratig raphic correlation of the turnround boundaries of different order base-level including short and middle termcycle sequence, the sequence and time stratigraphic framework can be built that in the scale of supershort-term base-level cycle as an isochronous unit, which are of varied application significance in hydrocarbon exploration and development, such as isochronous stratig raphic correlation of small sandbodies with oil, charting of isochronic microfacies in the large scale, description of sandbody geometry, forecasting reservoir and petroleum accumulation, analy sing reservoir heterogeneity, reservoir modeling and so on.
Through the comprehensive analysis of outcrops, cores, well logs and seismic interpretation data, and under the guidance of the theory and technology of the high-resolution sequence stratig raphy initiated by Timothy A-Cross in 1994, the characteristics of the different grade sequence interface and laucstrine flooding surface in the second member of Nadu Formation Eocene in Lun-35 Block of Ziyin Oil Field from Base Basin are studied.According to the identification sign of the sequence interface and flooding sedimentation, four-grade base-level cycle sequences that are divided into 13 ～ 18 supershort-term, 7 ～ 9 short-term, two middle-term, and one long-term cycle sequences are recognized from the formation.On the basis of these studies, the vertical sequence, facies association, lithologic component, structure type and stacking pattern are discussed in detail.Among these sequences, the supershort-term and short-term cycle sequence may be divided into two basic types of st ructure which are up-deepening non-symmetry and symmetry from up-deepening to up-shallowening.The first can be divided further into two subtypes of low or high accommodation and the second can be devided further into three subtypes of non-complete or nearly complete symmetry.These basic sequence types and subtypes are of various stacking and distribution patterns.The structure type and stacking pattern of the middle-term cycle sequence are the same as that of the shortterm cycle sequence.The long-term cycle sequence are of non-complete symmetric st ructure which develop complete depositional sequence of lacust rine transgressive-reg ressive cycle, and thickness of rising half-cycle is larger than the falling half-cycle.According to the high-resolution isochronous stratig raphic correlation of the turnround boundaries of different order base-level including short and middle termcycle sequence, the sequence and time stratigraphic framework can be built that in the scale of supershort-term base-level cycle as an isochronous unit, which are of varied application significance in hydrocarbon exploration and development, such as isochronous stratig raphic correlation of small sandbodies with oil, charting of isochronic microfacies in the large scale, description of sandbody geometry, forecasting reservoir and petroleum accumulation, analy sing reservoir heterogeneity, reservoir modeling and so on.
2003, 21(4): 670-674.
Abstract:
The sequence stratig raphy studies of the Shahejie Formation in the central uplift belt of Huimin depression of Shandong province indicate that tectonic movement and climate are dominant controlling factors to sequence development.The 2, 3and 4 submembers of Shahejie Formation can be divided into three types of stratig raphic sequence, i.e.the stratigraphic sequence in primary rifting stage, the st ratigraphic sequence in violent rifting stage and the stratigraphic sequence in the later rifting stage.The sequence stratig raphy indicates that it is more suitable to divide a sequence into four system tracts in the lacusstrine basin including low stand system tract(LTS), lake-transgressive system tract (TST), highstand system ract (HST)and falling-stage tract (FST).According to characteristics of lake level change and its corresponding sediments, the sequence boundary is located between the LST and FST.The red beds stratig raphic sequence is mainly controlled by the climate and has unique characteristics in sequence evolution, which is different from the alluvial fan stratigraphic sequence and also different from the normal lake facies stratig raphic sequence.Influenced by tectonic movement and sediment supply,three kinds of stratigraphic sequence in this region form three kinds of condensed sections, which located in different section of each sequence.The different condensed section will influence the abundance of source rock and resources, and every condensed section controls the distribution and thickness of the source rock.
The sequence stratig raphy studies of the Shahejie Formation in the central uplift belt of Huimin depression of Shandong province indicate that tectonic movement and climate are dominant controlling factors to sequence development.The 2, 3and 4 submembers of Shahejie Formation can be divided into three types of stratig raphic sequence, i.e.the stratigraphic sequence in primary rifting stage, the st ratigraphic sequence in violent rifting stage and the stratigraphic sequence in the later rifting stage.The sequence stratig raphy indicates that it is more suitable to divide a sequence into four system tracts in the lacusstrine basin including low stand system tract(LTS), lake-transgressive system tract (TST), highstand system ract (HST)and falling-stage tract (FST).According to characteristics of lake level change and its corresponding sediments, the sequence boundary is located between the LST and FST.The red beds stratig raphic sequence is mainly controlled by the climate and has unique characteristics in sequence evolution, which is different from the alluvial fan stratigraphic sequence and also different from the normal lake facies stratig raphic sequence.Influenced by tectonic movement and sediment supply,three kinds of stratigraphic sequence in this region form three kinds of condensed sections, which located in different section of each sequence.The different condensed section will influence the abundance of source rock and resources, and every condensed section controls the distribution and thickness of the source rock.
2003, 21(4): 683-687.
Abstract:
With the result of chronological research, sedimentology has been used to study the Tertiary sediments of Yongdeng Section of Lanzhou Basin and analyzed the changes of sedimentary environment and climate since Cenozoic.A set of fan delta deposits formed from the late Paleocene to early Eocene is red sandstone with crossstratification.The age of upper layers is about 51Ma.Great environmental changes took place in Lanzhou area at 51MaB.P.,which led to the climate transformation from warm and humid to semiarid and serihumid and climate was characterized by hot.Lake bed changed from freshw ater to salty, which implied the diversion toward north of arid zone controlled by semit ropical high-pressure belt.Lanzhou area became arid zone controlled by planetary wind system.The basin had a stage from slig ht saline-lake to salt-lake(Yiehusheng Formation)within the interval of about 20Ma(from late early Eocene to early early Oligocene(51 ～ 31.5Ma)), sand-mud stone contains plenty of interbeds of gypsum.The area was converting to moist climate in early Oligocene.Lanzhou Basin changed from saltwater lake to fresh lake,which probably indicates gradual formation of southeast monsoon.Mainland of China has been cont rolled by the monsoon instead of planetary wind system befo re.East-westward arid zone disappeared in early period and north-westward arid zone appeared.The area became moist comparing to before.Having endured three great cycles of sedimentation from the middle early Oligocene to middle Miocene (31.5 ～ 15Ma), the basinhad died gradually.The three cycles are respectively composed of sandstone of river facies —sand-mud stone of shore facies of light saline-lake, sandstone of river facies —sand-mud stone of shore facies of freshlake —mudstone of marsh facies and valley plain facies, sandstone of river facies—mudstone of marsh facies and valley plain facies.Plenty of the sediments of sand and gravel deposited in the basin at 20MaB.P., which reflects fast uplift of surrounding mountain mass and consequent degradation and implied that uplift of Qing hai-Tibean Plateau had influence on Lanzhou area.
With the result of chronological research, sedimentology has been used to study the Tertiary sediments of Yongdeng Section of Lanzhou Basin and analyzed the changes of sedimentary environment and climate since Cenozoic.A set of fan delta deposits formed from the late Paleocene to early Eocene is red sandstone with crossstratification.The age of upper layers is about 51Ma.Great environmental changes took place in Lanzhou area at 51MaB.P.,which led to the climate transformation from warm and humid to semiarid and serihumid and climate was characterized by hot.Lake bed changed from freshw ater to salty, which implied the diversion toward north of arid zone controlled by semit ropical high-pressure belt.Lanzhou area became arid zone controlled by planetary wind system.The basin had a stage from slig ht saline-lake to salt-lake(Yiehusheng Formation)within the interval of about 20Ma(from late early Eocene to early early Oligocene(51 ～ 31.5Ma)), sand-mud stone contains plenty of interbeds of gypsum.The area was converting to moist climate in early Oligocene.Lanzhou Basin changed from saltwater lake to fresh lake,which probably indicates gradual formation of southeast monsoon.Mainland of China has been cont rolled by the monsoon instead of planetary wind system befo re.East-westward arid zone disappeared in early period and north-westward arid zone appeared.The area became moist comparing to before.Having endured three great cycles of sedimentation from the middle early Oligocene to middle Miocene (31.5 ～ 15Ma), the basinhad died gradually.The three cycles are respectively composed of sandstone of river facies —sand-mud stone of shore facies of light saline-lake, sandstone of river facies —sand-mud stone of shore facies of freshlake —mudstone of marsh facies and valley plain facies, sandstone of river facies—mudstone of marsh facies and valley plain facies.Plenty of the sediments of sand and gravel deposited in the basin at 20MaB.P., which reflects fast uplift of surrounding mountain mass and consequent degradation and implied that uplift of Qing hai-Tibean Plateau had influence on Lanzhou area.
2003, 21(4): 702-706.
Abstract:
In a maturity, the proportion derived between the gaseous hydrocarbon productivity and the final productivity of gaseous hydrocarbon from organic matter is the ratio of productivity, the connection between the ratio of productivity and maturity can be established by means of analyzing productivity ratio of the same type organic matter in different stage.The balance of element is a balance among matter, which exits between organic matter and its product and residual product.This paper mainly discusses the hydrocarbon-producing potential of carbonate rocks in Ordovician system of lower Paleozoic group in Odros basin by employing the method of ratio of productivity and element balance, and find that carbonate rock containing clay can produce some amount of hydrocarbon in Ordovician system of lower Paleozoic group and its final productivity of gaseous hydrocarbon can reach the ratio of 420 ～ 430 m3/T·Co t, which corresponds with that of Ⅱ-ty pe kerogen.At the same time, the pure carbonate rock bear relative low hydrocarbon-producing potential (only 120 m3/ T·Cot)
In a maturity, the proportion derived between the gaseous hydrocarbon productivity and the final productivity of gaseous hydrocarbon from organic matter is the ratio of productivity, the connection between the ratio of productivity and maturity can be established by means of analyzing productivity ratio of the same type organic matter in different stage.The balance of element is a balance among matter, which exits between organic matter and its product and residual product.This paper mainly discusses the hydrocarbon-producing potential of carbonate rocks in Ordovician system of lower Paleozoic group in Odros basin by employing the method of ratio of productivity and element balance, and find that carbonate rock containing clay can produce some amount of hydrocarbon in Ordovician system of lower Paleozoic group and its final productivity of gaseous hydrocarbon can reach the ratio of 420 ～ 430 m3/T·Co t, which corresponds with that of Ⅱ-ty pe kerogen.At the same time, the pure carbonate rock bear relative low hydrocarbon-producing potential (only 120 m3/ T·Cot)
2003, 21(4): 717-721.
Abstract:
This study focuses on changes of pH value of water after adding ten kinds of natural minerals, and composition changes of natural minerals after dipping water of partial acidity or partial alkalescency.At the same time, the effect of ten type natural minerals and their dif ferent pH values on hydrolyzed catalysis on fatty acid has also been studied.The hydrolysis rates of fatty acid ester have been obtained by the presence of ten kinds of natural minerals.Our results show that different minerals will bring changes of pH value of paritial acidity or partial alkalescency, but the mineral components have not changed after dipping water of partial acidity or partial alkalescency. Many minerals except for dolomite and Ca-montmorillonite in the partial alkalescency are relatively favorable for hydrolysis of fatty acid ester at low temperature.The hydrolysis rates of fatty acid ester catalyzed by minerals at low temperature are ranging from 90% to 50%,mostly in 22%～ 34%.
This study focuses on changes of pH value of water after adding ten kinds of natural minerals, and composition changes of natural minerals after dipping water of partial acidity or partial alkalescency.At the same time, the effect of ten type natural minerals and their dif ferent pH values on hydrolyzed catalysis on fatty acid has also been studied.The hydrolysis rates of fatty acid ester have been obtained by the presence of ten kinds of natural minerals.Our results show that different minerals will bring changes of pH value of paritial acidity or partial alkalescency, but the mineral components have not changed after dipping water of partial acidity or partial alkalescency. Many minerals except for dolomite and Ca-montmorillonite in the partial alkalescency are relatively favorable for hydrolysis of fatty acid ester at low temperature.The hydrolysis rates of fatty acid ester catalyzed by minerals at low temperature are ranging from 90% to 50%,mostly in 22%～ 34%.
2003, 21(4): 553-559.
Abstract:
The types of sedimentary facies and sedimentary characteristics in Pukou Formation of Late Cretaceous System in Yanfu Depression are systematically analyzed, and the planar distribution of sedimentary facies in the members of Pukou Formation and the laws of facies evolution are studied in detail.The conclusions show that Pukou Formation is mainly comprised by alluvial fans, fan deltas and lacustrine facies.In the basin, from the margin to the center, the facies developed from alluvial fans, gradually to fan deltas or lakefront facies, shallow-take facies, semi-deep lake facies, or saline lake facies;from the bottom to the top, the facies gradually changed from alluvial fans to fan-deltas or lakefront facies, to shallow-lake facies, semi-deep-lake facies or saline facies, finally to shallow-lake facies.The Pukou Formation can be divided into four stages:initial stage, fore-stage, metaphase and terminal-stage.The sedimentary characteristics are correspondingly different in various stages and areas.But, as a whole, the Yanfu Depression changed from narrow to wide, and then to narrow.
The types of sedimentary facies and sedimentary characteristics in Pukou Formation of Late Cretaceous System in Yanfu Depression are systematically analyzed, and the planar distribution of sedimentary facies in the members of Pukou Formation and the laws of facies evolution are studied in detail.The conclusions show that Pukou Formation is mainly comprised by alluvial fans, fan deltas and lacustrine facies.In the basin, from the margin to the center, the facies developed from alluvial fans, gradually to fan deltas or lakefront facies, shallow-take facies, semi-deep lake facies, or saline lake facies;from the bottom to the top, the facies gradually changed from alluvial fans to fan-deltas or lakefront facies, to shallow-lake facies, semi-deep-lake facies or saline facies, finally to shallow-lake facies.The Pukou Formation can be divided into four stages:initial stage, fore-stage, metaphase and terminal-stage.The sedimentary characteristics are correspondingly different in various stages and areas.But, as a whole, the Yanfu Depression changed from narrow to wide, and then to narrow.
2003, 21(4): 565-570.
Abstract:
As a new type of rivers, anastomosing river has been concerned by researchers although some questions about it was not clear for understanding it.This paper discusses the river architectures, relationships between width/depth ratios of stream cross sections and discharges, and stream powers of anastomosing rivers according to references and obtained data recently.It is helpful to researchers who is interested in this river pattern to develop the theory for it. Many aspects of anastomosing river appear particular characteristics compared with other river patterns.In the planform architectures, the multiple channels joining each other enclose flood basins on which vegetation,swamps and lakes develop basically.Longitudinal gradients of the channels are very low while the channel width/depth ratios are smaller than 40.In the depositional architectures of cross profiles, some isolated sand-bodies of channel deposits are ”floating” in the mud-bodies of flood basins.In the half-logarithm diagram of width/depth ratios of stream cross profiles vs.discharges, the scatters of anastomosing rivers are below compared with that of other river patterns.The stream powers of anastomosing rivers are very low compared with the old trunk channel from which it diverted because the channel gradients and discharges of every anastomosing channel are smaller than that of the old trunk channel.The specific stream power of the anastomosing channels:eastern Song zi River, western Song zi River, Hudu River, Ouchi River, northern Ouchi River and Songliheliu River are 3.0 W/m2, 5.5 W/m2,2.8 W/m2, 6.4 W/m2, 3.7 W/m2 and 2.7 W/m2, respectively.Obviously, all of them are smaller than 10 W/m2.But the specific stream power of anabranched Chang jiang trunk channel is 140 W/m2.All of the characteristics of anastomosing rivers indicate that this river pattern is different from the anabranched rivers represented by the lower Chang jiang River, especially from other river patterns.
As a new type of rivers, anastomosing river has been concerned by researchers although some questions about it was not clear for understanding it.This paper discusses the river architectures, relationships between width/depth ratios of stream cross sections and discharges, and stream powers of anastomosing rivers according to references and obtained data recently.It is helpful to researchers who is interested in this river pattern to develop the theory for it. Many aspects of anastomosing river appear particular characteristics compared with other river patterns.In the planform architectures, the multiple channels joining each other enclose flood basins on which vegetation,swamps and lakes develop basically.Longitudinal gradients of the channels are very low while the channel width/depth ratios are smaller than 40.In the depositional architectures of cross profiles, some isolated sand-bodies of channel deposits are ”floating” in the mud-bodies of flood basins.In the half-logarithm diagram of width/depth ratios of stream cross profiles vs.discharges, the scatters of anastomosing rivers are below compared with that of other river patterns.The stream powers of anastomosing rivers are very low compared with the old trunk channel from which it diverted because the channel gradients and discharges of every anastomosing channel are smaller than that of the old trunk channel.The specific stream power of the anastomosing channels:eastern Song zi River, western Song zi River, Hudu River, Ouchi River, northern Ouchi River and Songliheliu River are 3.0 W/m2, 5.5 W/m2,2.8 W/m2, 6.4 W/m2, 3.7 W/m2 and 2.7 W/m2, respectively.Obviously, all of them are smaller than 10 W/m2.But the specific stream power of anabranched Chang jiang trunk channel is 140 W/m2.All of the characteristics of anastomosing rivers indicate that this river pattern is different from the anabranched rivers represented by the lower Chang jiang River, especially from other river patterns.
2003, 21(4): 579-585.
Abstract:
Many fish-produced markings are well developed on the argillaceous sediment overlying the Yellow River point bar.They are:(1)swimming trace, i.e.the simple wave line elongating in the linear or nonlinear form due to the scratch of the tail fin of fish;the simple line elongating in the linear form induced by anal fin;the parallel paired wave line on the argillaceous sediment caused by the vent ral fin;the intermittent discordant paired wave line caused by the swing of pectoral fin;and the combinations of wave lines above.(2)round or pit-like pascichnia, combined together in the grape, curved, disperse, linear, zig zag, banded form etc, produced by the fish grazinging.(3)fecal pellet.In this paper, the feature, genesis, and the environment related to the fish-produced markings are discussed in detail, and therefore inferring that the argillaceous sediment subsiding slowly is the prerequisite for the forming and preservation of fish-produced markings.
Many fish-produced markings are well developed on the argillaceous sediment overlying the Yellow River point bar.They are:(1)swimming trace, i.e.the simple wave line elongating in the linear or nonlinear form due to the scratch of the tail fin of fish;the simple line elongating in the linear form induced by anal fin;the parallel paired wave line on the argillaceous sediment caused by the vent ral fin;the intermittent discordant paired wave line caused by the swing of pectoral fin;and the combinations of wave lines above.(2)round or pit-like pascichnia, combined together in the grape, curved, disperse, linear, zig zag, banded form etc, produced by the fish grazinging.(3)fecal pellet.In this paper, the feature, genesis, and the environment related to the fish-produced markings are discussed in detail, and therefore inferring that the argillaceous sediment subsiding slowly is the prerequisite for the forming and preservation of fish-produced markings.
2003, 21(4): 607-614.
Abstract:
“Hunji” rocks of the lower part of number 1 of Shahejie Formation,Beach district,Dagang, are dominantly terrigenous clastithic-carbonate “Hunji” rock, subordinately carbonatic-terrigenous clastic “Hunji” rock and carbonate bearing-terrigenous clastic “Hunji” rock.“Hunji” rock of Baishuitou district lies in braided stream-fan delta front subfluvial branching river deposits,which mixed by gradual facies change.While Madong-Madong dong district is distributed in gravity flow deposit systems, mixed by turbidites.“Hunji” rocks of this area experienced compaction, cementation and dissolution /alteration process.Pore fluid experienced alkaline to acid and return to alkaline.The association of glauconite and micro-calcite cement, calcite precipi ation and a part of quartz dissolution is with alkaline pore fluid;The association of hydrocarbon emplacement, dissolution, quartz overgrowth and kaolinite precipitation is with acid pore fluid;And the association of illite, chlorite, albitization, pore-filling calcite and dolomite is with alkaline pore fluid.
“Hunji” rocks of the lower part of number 1 of Shahejie Formation,Beach district,Dagang, are dominantly terrigenous clastithic-carbonate “Hunji” rock, subordinately carbonatic-terrigenous clastic “Hunji” rock and carbonate bearing-terrigenous clastic “Hunji” rock.“Hunji” rock of Baishuitou district lies in braided stream-fan delta front subfluvial branching river deposits,which mixed by gradual facies change.While Madong-Madong dong district is distributed in gravity flow deposit systems, mixed by turbidites.“Hunji” rocks of this area experienced compaction, cementation and dissolution /alteration process.Pore fluid experienced alkaline to acid and return to alkaline.The association of glauconite and micro-calcite cement, calcite precipi ation and a part of quartz dissolution is with alkaline pore fluid;The association of hydrocarbon emplacement, dissolution, quartz overgrowth and kaolinite precipitation is with acid pore fluid;And the association of illite, chlorite, albitization, pore-filling calcite and dolomite is with alkaline pore fluid.
2003, 21(4): 620-626.
Abstract:
Bedded cherts, with varying thickness, are widely distributed in some typical eopaleozoic high Se black shales in China.Bedded cherts are mainly composed of SiO2in chemical composition, generally more than 90%with relatively high content of Fe and low content of Mn, Al, Ti.Lithophile elements deplete in cherts, however some elements like As, Ba, Sb, etc., which are typically indicative elements for hydrothermal sedimentation, are rich in cherts.REE distribution pattern show obvious left slope with clearly negative Ce anomaly and slightly positive Eu anomaly.δ30Si values of cherts range from -0.7 ‰ to 1.2 ‰, and δ18O values of cherts range from 17.6 ‰ to 29.0 ‰.Above much evidence suggests that origin of bedded cherts mghit be ascribed to hydrothermal sedimentation.At last of the paper, the relationship between hydrothermal cherts and enrichment of Se is discussed.Based on some indirect evidence, it can be concluded that the tectonic environment that hosts cherts should be a prerequisite for the ascension of Se from the deep depth in the crust and for its enrichment at the shallow depth.In the meantime, Si-bearing hydrothermal solutions might be a desirable ”solvent ” for Se.
Bedded cherts, with varying thickness, are widely distributed in some typical eopaleozoic high Se black shales in China.Bedded cherts are mainly composed of SiO2in chemical composition, generally more than 90%with relatively high content of Fe and low content of Mn, Al, Ti.Lithophile elements deplete in cherts, however some elements like As, Ba, Sb, etc., which are typically indicative elements for hydrothermal sedimentation, are rich in cherts.REE distribution pattern show obvious left slope with clearly negative Ce anomaly and slightly positive Eu anomaly.δ30Si values of cherts range from -0.7 ‰ to 1.2 ‰, and δ18O values of cherts range from 17.6 ‰ to 29.0 ‰.Above much evidence suggests that origin of bedded cherts mghit be ascribed to hydrothermal sedimentation.At last of the paper, the relationship between hydrothermal cherts and enrichment of Se is discussed.Based on some indirect evidence, it can be concluded that the tectonic environment that hosts cherts should be a prerequisite for the ascension of Se from the deep depth in the crust and for its enrichment at the shallow depth.In the meantime, Si-bearing hydrothermal solutions might be a desirable ”solvent ” for Se.
2003, 21(4): 634-639.
Abstract:
Heat generation is an important thermal parameter used to describe the thermal status of the Earth. Only the rock sample density data, the abundance data of the radioative elements U, Th,K are used to calculate the heat generation of the rock sample.Drilling well sample and sea floor sample from East China Sea Shelf and core sample from Okinaw a Trough were collected, and the heat generation of each sample was calculated based on the abundance of the radio elements of each samples.The results show that all the heat generation data of the Cenozoic layer of the East China Shelf are between 0.4 ～ 1.7μW/m3,which is in the sediment heat generation data range and a little bit higher than that of igneous rock.We find that the lithology control' s the heat generation, different rocks have different heat generation.Mudstone has highest heat generation comparing with silt stone and sandstone.The heat generation of the Cenozoic layer of East China Sea shelf is decreasing as the layer age become old.But the heat generation of the Yuquan group, Long jing group and Huagang group is almost the same that tallies with velocity rule of the three groups.The equation ln A =1.04 -0.2915vp, which is given by this paper, can describe the relationship between the heat generation and velocity well and can be used to calculate the heat generation on the Cenozoic Layer of the East China Sea Shelf when there is velocity data available.
Heat generation is an important thermal parameter used to describe the thermal status of the Earth. Only the rock sample density data, the abundance data of the radioative elements U, Th,K are used to calculate the heat generation of the rock sample.Drilling well sample and sea floor sample from East China Sea Shelf and core sample from Okinaw a Trough were collected, and the heat generation of each sample was calculated based on the abundance of the radio elements of each samples.The results show that all the heat generation data of the Cenozoic layer of the East China Shelf are between 0.4 ～ 1.7μW/m3,which is in the sediment heat generation data range and a little bit higher than that of igneous rock.We find that the lithology control' s the heat generation, different rocks have different heat generation.Mudstone has highest heat generation comparing with silt stone and sandstone.The heat generation of the Cenozoic layer of East China Sea shelf is decreasing as the layer age become old.But the heat generation of the Yuquan group, Long jing group and Huagang group is almost the same that tallies with velocity rule of the three groups.The equation ln A =1.04 -0.2915vp, which is given by this paper, can describe the relationship between the heat generation and velocity well and can be used to calculate the heat generation on the Cenozoic Layer of the East China Sea Shelf when there is velocity data available.
2003, 21(4): 648-653.
Abstract:
The analysis of reservoir fluid inclusions is a useful method in studying hydrocarbon migration and entrapment.Four homogenization temperature groups, 75 ～ 105 ℃, 120 ～ 135 ℃, 155 ～ 175 ℃ and 200 ～ 250 ℃, are obtained, based on testing reservoir fluid inclusions systematically sampled from Well Kela-201 in Kela 2 gas field. The former three homogenization temperature groups are related to the hydrocarbon entrapment in Kela 2 gas field, and the last one or the higher temperatures may be related to the action of the hydrothermal fluid from the deep.In combination with the reconst ruction of the burial history and thermal history, it is shown that the time of hydrocarbon entrapment in Kela 2 gas field is 11 ～ 2.5Ma, beginning at the sedimentary time of Kangcun Formation to Kuche Formation and ending at the denudation time of Kuche Formation.The gas field could be altered by the action of hydrothermal fluid.
The analysis of reservoir fluid inclusions is a useful method in studying hydrocarbon migration and entrapment.Four homogenization temperature groups, 75 ～ 105 ℃, 120 ～ 135 ℃, 155 ～ 175 ℃ and 200 ～ 250 ℃, are obtained, based on testing reservoir fluid inclusions systematically sampled from Well Kela-201 in Kela 2 gas field. The former three homogenization temperature groups are related to the hydrocarbon entrapment in Kela 2 gas field, and the last one or the higher temperatures may be related to the action of the hydrothermal fluid from the deep.In combination with the reconst ruction of the burial history and thermal history, it is shown that the time of hydrocarbon entrapment in Kela 2 gas field is 11 ～ 2.5Ma, beginning at the sedimentary time of Kangcun Formation to Kuche Formation and ending at the denudation time of Kuche Formation.The gas field could be altered by the action of hydrothermal fluid.
2003, 21(4): 663-669.
Abstract:
Pucheng oil field is located in the Dongpu depress, Henan province. In this study, a method based on baselevel analysis for stratigraphy correlation in the development stage is provided. The characteristics of stratigraphic surface and stratigraphy sequence in the seismic, well log and cores are summarized. Four scales of sequence cycles are disting uished in the study area, including very short term cycle, short term one, middle term one and long term cycle. Long term cycle is corresponding to sub-fan complex, and middle cycles to fan slove, and short one to fan lobe, which is the smallest units for adjusting in the production. In the study zone, 6 medium term and 27 short term cycles are distinguished and correlated.
Pucheng oil field is located in the Dongpu depress, Henan province. In this study, a method based on baselevel analysis for stratigraphy correlation in the development stage is provided. The characteristics of stratigraphic surface and stratigraphy sequence in the seismic, well log and cores are summarized. Four scales of sequence cycles are disting uished in the study area, including very short term cycle, short term one, middle term one and long term cycle. Long term cycle is corresponding to sub-fan complex, and middle cycles to fan slove, and short one to fan lobe, which is the smallest units for adjusting in the production. In the study zone, 6 medium term and 27 short term cycles are distinguished and correlated.
2003, 21(4): 675-682.
Abstract:
It is well known that the key of research on sequence stratigraphy is sequence division, but first of all the key of sequence division is identification of boundary surface. The boundary surface of defined sequence included sequence bottom boundary surface first trangressive surface and maximum marine f looding surface. Among them, the most important is bottom boundary surface indentification because it is sequence division foundation. The paper, taking marine Sinian system to Middle Triassic Series in south China as an example, through anlyses of filed geologic sections, identified nine types sequence bottom boundary surfaces which are: ( 1) weathering crust;(2) Paleosol;(3) Erosion surface of river rejuvenation;(4) Action surface of ancient karst;(5) Washing erosion surface of gravity flow on slop;(6) Erosion surface of turbidity flow in basin;(7) Action surface of volcano event;(8) Transition surface of rock character and facies;(9) onlap surface. Research features of above boundary surfaces in detail is very important for sequence division.
It is well known that the key of research on sequence stratigraphy is sequence division, but first of all the key of sequence division is identification of boundary surface. The boundary surface of defined sequence included sequence bottom boundary surface first trangressive surface and maximum marine f looding surface. Among them, the most important is bottom boundary surface indentification because it is sequence division foundation. The paper, taking marine Sinian system to Middle Triassic Series in south China as an example, through anlyses of filed geologic sections, identified nine types sequence bottom boundary surfaces which are: ( 1) weathering crust;(2) Paleosol;(3) Erosion surface of river rejuvenation;(4) Action surface of ancient karst;(5) Washing erosion surface of gravity flow on slop;(6) Erosion surface of turbidity flow in basin;(7) Action surface of volcano event;(8) Transition surface of rock character and facies;(9) onlap surface. Research features of above boundary surfaces in detail is very important for sequence division.
2003, 21(4): 695-700.
Abstract:
A series of Cretaceous lacustrine mudstone, shale, dolomitic mudstone and argillaceous dolostone comprises the main source rocks of Qing xi Sag in the study area.During deposition, the Qingxi Sag was a closed to semi-closed rift basin with strong reducing conditions that was favorable for the preservation and transformation of organic matter.In addition, the thickness of the source rock is very great with the ratio of source rock to st rata over 50%, together with mixing organic types, high content of organic carbon (>1%), which all provided the important material basis for oil pool formation.Himalayan tectonic movement formed lots of compressional reverse faults, shears faults and structural fissures, and resulted instrata and st ructure overstacking to provide impetus and space for organic matter maturity, migration and accumulation of petroleum.
A series of Cretaceous lacustrine mudstone, shale, dolomitic mudstone and argillaceous dolostone comprises the main source rocks of Qing xi Sag in the study area.During deposition, the Qingxi Sag was a closed to semi-closed rift basin with strong reducing conditions that was favorable for the preservation and transformation of organic matter.In addition, the thickness of the source rock is very great with the ratio of source rock to st rata over 50%, together with mixing organic types, high content of organic carbon (>1%), which all provided the important material basis for oil pool formation.Himalayan tectonic movement formed lots of compressional reverse faults, shears faults and structural fissures, and resulted instrata and st ructure overstacking to provide impetus and space for organic matter maturity, migration and accumulation of petroleum.
2003, 21(4): 713-716.
Abstract:
Hydrous pyrolysis using hig h-pressure autoclave, nowadays, is a relatively effective way to study petroleum geochemistry,which can simulate the process of oil and gas formation.In general, high percentage hydrogen is often found in the gas pyrolysate produced from organic in hydrous simulation experiments, which employ high-pressure autoclave.Most people beliveve the hydrogen mainly comes from organic reactions.In order to prove this problem, the authors have done a series of simulation experiments.In the experiment, the material of high-pressure autoclave is an alloy made from 1Cr18Ni9Ti and OCr17Ni12Mo2.The temperature of the experiments are under 330 ℃ and 330 ℃ for 72 hours.The quantity of water is accurately calculated.The experiment items include organic and inorganic matters, such as Fushun oil shale,Kaolinite and the deionized water, etc.The results several experiments show that the sources of hydrogen are not only organic reactions but also inorganic reactons.Particularly.the reactions in which only the deionized water is added into the high-pressure autoclave, also release hydrogen. This result proves the reaction between the high-pressure autoclaves and the deionized water at high thermal stress effectively.So the series of simulation experiment using high-pressure autoclave should be thought over and be modified, or the validity of the analysis and explanation of such experiments will be not reliable.
Hydrous pyrolysis using hig h-pressure autoclave, nowadays, is a relatively effective way to study petroleum geochemistry,which can simulate the process of oil and gas formation.In general, high percentage hydrogen is often found in the gas pyrolysate produced from organic in hydrous simulation experiments, which employ high-pressure autoclave.Most people beliveve the hydrogen mainly comes from organic reactions.In order to prove this problem, the authors have done a series of simulation experiments.In the experiment, the material of high-pressure autoclave is an alloy made from 1Cr18Ni9Ti and OCr17Ni12Mo2.The temperature of the experiments are under 330 ℃ and 330 ℃ for 72 hours.The quantity of water is accurately calculated.The experiment items include organic and inorganic matters, such as Fushun oil shale,Kaolinite and the deionized water, etc.The results several experiments show that the sources of hydrogen are not only organic reactions but also inorganic reactons.Particularly.the reactions in which only the deionized water is added into the high-pressure autoclave, also release hydrogen. This result proves the reaction between the high-pressure autoclaves and the deionized water at high thermal stress effectively.So the series of simulation experiment using high-pressure autoclave should be thought over and be modified, or the validity of the analysis and explanation of such experiments will be not reliable.
