2008 Vol. 26, No. 5
Display Method:
2008, 26(5): 715-724.
Abstract:
Sand bank sandstones are one of the important reservoirs in nonmarine basins of China. Bank genetic reservoir prediction is not easy due to its thin bed characters. This paper summarizes the identification marks of sand bank and barrier in lake. Isochronous stratigraphic units are divided based on highresolution sequence stratigraphy principle, sand bank and barrier distribution and its controls are analyzed in time stratigraphic units, and also sedimentary models of bank and barrier are established. This study provides the geologic foundation for oil and gas exploration in sand bank reservoirs.
Sand bank sandstones are one of the important reservoirs in nonmarine basins of China. Bank genetic reservoir prediction is not easy due to its thin bed characters. This paper summarizes the identification marks of sand bank and barrier in lake. Isochronous stratigraphic units are divided based on highresolution sequence stratigraphy principle, sand bank and barrier distribution and its controls are analyzed in time stratigraphic units, and also sedimentary models of bank and barrier are established. This study provides the geologic foundation for oil and gas exploration in sand bank reservoirs.
2008, 26(5): 730-736.
Abstract:
Comprehensively using the drilling, logging and seismic data, based on the boundary characteristics of the sequence systems tract, sequences of Ed Formation in Paleogene in the area of Nanpu sag were classified. Ed Formations were divided into three sedimentary sequences. By tracing MFS and FFS, lowstand, transgressive and highstand system tracts was ascertained. The basin palaeogeography and fault activity have influenced on framework and distributions of the sequence. On the area of hangingwall of Gaoliu fault, Ed Formation was thin and eroded hardly, especially in Liuzan region. The centre of sequence thickness was located on Linque subsag, thickness is more than 2500m.While on the land, average sequence thickness is 1800m. Depositional systems were analysis on sequence stratigraphic framework. On the slope region in the northeast, alluvial fan and fandelta were mainly depositional systems. And braided riverdelta, fan delta and delta were distributed in the northwest and south slope. Tectonic activities were critical controlling factors on sequence system boundary; stack mode and distribution of deposition system. Strong active fault make retrogradation mode, and inertia fault make progradation. The favorable lithological traps are located mainly on fandelta in the lowstand system tracts of sequence1 and on turbidite fan in the sequence 2.
Comprehensively using the drilling, logging and seismic data, based on the boundary characteristics of the sequence systems tract, sequences of Ed Formation in Paleogene in the area of Nanpu sag were classified. Ed Formations were divided into three sedimentary sequences. By tracing MFS and FFS, lowstand, transgressive and highstand system tracts was ascertained. The basin palaeogeography and fault activity have influenced on framework and distributions of the sequence. On the area of hangingwall of Gaoliu fault, Ed Formation was thin and eroded hardly, especially in Liuzan region. The centre of sequence thickness was located on Linque subsag, thickness is more than 2500m.While on the land, average sequence thickness is 1800m. Depositional systems were analysis on sequence stratigraphic framework. On the slope region in the northeast, alluvial fan and fandelta were mainly depositional systems. And braided riverdelta, fan delta and delta were distributed in the northwest and south slope. Tectonic activities were critical controlling factors on sequence system boundary; stack mode and distribution of deposition system. Strong active fault make retrogradation mode, and inertia fault make progradation. The favorable lithological traps are located mainly on fandelta in the lowstand system tracts of sequence1 and on turbidite fan in the sequence 2.
2008, 26(5): 744-752.
Abstract:
By the research of core, logging profiles and micropaleontology, marine delta facies of Zhuhai Formation have been recognized in Huizhou Depresion. On the basis of integrating well data and seismic data, combined with the high resolution sequence stratigraphic theory, the marine delta sedimentary system of Zhuhai Formation from Huizhou depression of Pearl River Mouth basin, was divided into shortterm ,middleterm and longterm baselevel cycle. The structure of the shortterm baselevel cycle could be subdivided into asymmetric updeepening , asymmetric upshallowening and symmetric basic structure types. The baselevel cycles of different order are correlated in the restriction of seismic interpretations and method of cycle isochrostratigraphy correlation. Isochronous stratigraphic frameworks are established and single sandbody is correlated within them. Finally, the distribution and evolution of reservoir are analyzed within isochronous stratigraphic frameworks.
By the research of core, logging profiles and micropaleontology, marine delta facies of Zhuhai Formation have been recognized in Huizhou Depresion. On the basis of integrating well data and seismic data, combined with the high resolution sequence stratigraphic theory, the marine delta sedimentary system of Zhuhai Formation from Huizhou depression of Pearl River Mouth basin, was divided into shortterm ,middleterm and longterm baselevel cycle. The structure of the shortterm baselevel cycle could be subdivided into asymmetric updeepening , asymmetric upshallowening and symmetric basic structure types. The baselevel cycles of different order are correlated in the restriction of seismic interpretations and method of cycle isochrostratigraphy correlation. Isochronous stratigraphic frameworks are established and single sandbody is correlated within them. Finally, the distribution and evolution of reservoir are analyzed within isochronous stratigraphic frameworks.
2008, 26(5): 762-771.
Abstract:
A great attention has been repaid to the study of the SilurianDevonian in the Tarim Basin due to the discovery of petroleum in the interval, but there still exists some basic geologic problems which hinder the exploration. Through comprehensive analysis of field section, drilling well and well core, on the basis of detailed strata division and comparison, the SilurianDevonian was identified three sedimentary system group (including continental facies, marinecontinental transition and marine sedimentary system group) in the Tarim Basin, and can be further identified eight sedimentary system. On the basis of the above sedimentary research, combining the identification of well logging and seismic facies. The detailed research on the character and spacetime evolvement of the lithofacies paleogeography of SilurianDevonian has been carvied out, and the research indicates that in the process of sedimentary evolvement, the character of lithofacies paleogeography is different in each phase, but it is succession. It shows that the dominant facies is shelf sea, shore and tidalflat in the whole Silurian, and the sedimentary facies zone is SouthNorth zonation, eastwest spread; from late Silurian to Devonian the sedimentary environment is shore and tidalflat, but the sedimentary facies zone is more limited; late Late Devonian the sedimentary environment is shore and tidalflat, and the sedimentary range is more shorten. The obtain of above research will provide base information for the studying of reservoir regulatities of distribution and petroleum forcasting.
A great attention has been repaid to the study of the SilurianDevonian in the Tarim Basin due to the discovery of petroleum in the interval, but there still exists some basic geologic problems which hinder the exploration. Through comprehensive analysis of field section, drilling well and well core, on the basis of detailed strata division and comparison, the SilurianDevonian was identified three sedimentary system group (including continental facies, marinecontinental transition and marine sedimentary system group) in the Tarim Basin, and can be further identified eight sedimentary system. On the basis of the above sedimentary research, combining the identification of well logging and seismic facies. The detailed research on the character and spacetime evolvement of the lithofacies paleogeography of SilurianDevonian has been carvied out, and the research indicates that in the process of sedimentary evolvement, the character of lithofacies paleogeography is different in each phase, but it is succession. It shows that the dominant facies is shelf sea, shore and tidalflat in the whole Silurian, and the sedimentary facies zone is SouthNorth zonation, eastwest spread; from late Silurian to Devonian the sedimentary environment is shore and tidalflat, but the sedimentary facies zone is more limited; late Late Devonian the sedimentary environment is shore and tidalflat, and the sedimentary range is more shorten. The obtain of above research will provide base information for the studying of reservoir regulatities of distribution and petroleum forcasting.
2008, 26(5): 780-788.
Abstract:
Based on the diagenetic modeling, the reservoir porosity of the lower Third Member of Shahejie Formation(Es3l) was predicted, and the porosity evolving histories was modeled, and the areas of effective oil and gas reservoirs were determined through building correlation models between the diagenetic intensity index(ID) and reservoir average porosity for various sedimentary microfacies of Shuangqing area of the Liaohe Depression. The results of porosity prediction show that the area of effective oil reservoirs with porosity greater than 8.5％ and effective gas reservoirs with porosity greater than 5.8％ are distributed on the slope zones. The absolute error between the predicted average porosity and measured porosity is 2.8％. However, the porefilling contents are up to 1.2%～45.0%, averaging at 16.9%.It means that these kinds of models are suitable for the porosity prediction and porosity evolving history modeling of classic rock reservoirs with more porefilling contents. The porosity evolving history modeling results suggest that the reservoir porosity during the early burial time is effected dominantly by sedimentary facies, but the reservoir porosity in the late burial time is controlled mainly by diagenesis.
Based on the diagenetic modeling, the reservoir porosity of the lower Third Member of Shahejie Formation(Es3l) was predicted, and the porosity evolving histories was modeled, and the areas of effective oil and gas reservoirs were determined through building correlation models between the diagenetic intensity index(ID) and reservoir average porosity for various sedimentary microfacies of Shuangqing area of the Liaohe Depression. The results of porosity prediction show that the area of effective oil reservoirs with porosity greater than 8.5％ and effective gas reservoirs with porosity greater than 5.8％ are distributed on the slope zones. The absolute error between the predicted average porosity and measured porosity is 2.8％. However, the porefilling contents are up to 1.2%～45.0%, averaging at 16.9%.It means that these kinds of models are suitable for the porosity prediction and porosity evolving history modeling of classic rock reservoirs with more porefilling contents. The porosity evolving history modeling results suggest that the reservoir porosity during the early burial time is effected dominantly by sedimentary facies, but the reservoir porosity in the late burial time is controlled mainly by diagenesis.
2008, 26(5): 797-803.
Abstract:
The Dingjiashan Formation of the Middle Permian in Jiangshan, Zhejiang Province is composed of the black lamellar and bedded cherts, siliceous siltstone, and siltstone intercalated with micrite. The black bedded cherts are characterized by high SiO2, rich in Al2O3 and Fe2O3, low TiO2 and MnO, low REE values, Ce deficiency and positive anomaly Tm value. The characteristics of cathodeluminescence and lithology have proved that these siliceous rocks were originated by replacement of sedimentary carbonates, such as bioclastic limestone, dolomitization were took place before silification. The chemical analysis data demonstrate that siliceous matter came from the normal underwater and continental silica gel, not from hydrothermal or volcanic silicon.
The Dingjiashan Formation of the Middle Permian in Jiangshan, Zhejiang Province is composed of the black lamellar and bedded cherts, siliceous siltstone, and siltstone intercalated with micrite. The black bedded cherts are characterized by high SiO2, rich in Al2O3 and Fe2O3, low TiO2 and MnO, low REE values, Ce deficiency and positive anomaly Tm value. The characteristics of cathodeluminescence and lithology have proved that these siliceous rocks were originated by replacement of sedimentary carbonates, such as bioclastic limestone, dolomitization were took place before silification. The chemical analysis data demonstrate that siliceous matter came from the normal underwater and continental silica gel, not from hydrothermal or volcanic silicon.
2008, 26(5): 813-819.
Abstract:
The 81 samples were collected over three profiles on typical coastal transverse foredune, which is directly across the foredune, at Changle coastal region in Fujian Province that is one of the most typical coastal aeolian distribution regions in China. The parameters of grain size of 81 samples were analyzed and calculated by use of the number of mean size, standard deviation, skewness and kurtosis. The results show that the basic characteristics of grain size over coastal transverse foredune are accordant with the normal rule of coastal aeolian dune grain size, such as fine sands, high sorting degree, symmetrical skewness and middle degree kurtosis. It was also found that the parameters of grain size at different sites over typical coastal transverse foredune were almost the same, which had no distinct difference. The reasons of this distribution pattern of grain size on coastal transverse foredune at Changle City in Fujian Province mainly lie on the change of wind directions depending on monsoon, the influence of typhoon, smooth surface and low height of dune as well as good vegetation cover.
The 81 samples were collected over three profiles on typical coastal transverse foredune, which is directly across the foredune, at Changle coastal region in Fujian Province that is one of the most typical coastal aeolian distribution regions in China. The parameters of grain size of 81 samples were analyzed and calculated by use of the number of mean size, standard deviation, skewness and kurtosis. The results show that the basic characteristics of grain size over coastal transverse foredune are accordant with the normal rule of coastal aeolian dune grain size, such as fine sands, high sorting degree, symmetrical skewness and middle degree kurtosis. It was also found that the parameters of grain size at different sites over typical coastal transverse foredune were almost the same, which had no distinct difference. The reasons of this distribution pattern of grain size on coastal transverse foredune at Changle City in Fujian Province mainly lie on the change of wind directions depending on monsoon, the influence of typhoon, smooth surface and low height of dune as well as good vegetation cover.
2008, 26(5): 828-832.
Abstract:
Chenghu is one of the shallow lakes in Taihu Plain, Jiangsu Province, China. The bottom of Chenghu is extremely flat, which is mainly composed of ‘hard clay’(a kind of sediment consisting of silt and clay), and has been featured with a NWSE paleochannel in the middle and shallow swamps in the middlewest. Sediment record in these paleochannel and swamps may become good archives, spanning from the Last Glacial to the Postglacial. This paper focuses on the hard clay of the lake bottom based on the study of the SC7 core (about 4 meters long) that drilled in the paleochannel at the bottom of the lake. The composition of the particlesize of the hard clay is discussed in detail. The hard clay in Chenghu mainly consists of fine silt, medium silt and clay; the content of fine silt from 26.7% to 38.1%, that of medium silt from 26.9% to 34.3%, that of clay from 19.7% to 26.2%, which belongs to clayey silt. The 10~50 μm particle group is the “dominate group” of the hard clay in Chenghu with the average content of 57.9%. The mean particlesize is from 6.3 to 6.9. Through the comparison of the particlesize characteristics among the hard clay in Chenghu, lake sediments, Xiashu Loess in Zhenjiang of Jiangsu Province and the northern China loesses in Qaidam, western Gansu, eastern Gansu, northern Shaanxi, western Shanxi and Shandong Province, we tend to conclude that the hard clay in Chenghu is of aeolian origin.
Chenghu is one of the shallow lakes in Taihu Plain, Jiangsu Province, China. The bottom of Chenghu is extremely flat, which is mainly composed of ‘hard clay’(a kind of sediment consisting of silt and clay), and has been featured with a NWSE paleochannel in the middle and shallow swamps in the middlewest. Sediment record in these paleochannel and swamps may become good archives, spanning from the Last Glacial to the Postglacial. This paper focuses on the hard clay of the lake bottom based on the study of the SC7 core (about 4 meters long) that drilled in the paleochannel at the bottom of the lake. The composition of the particlesize of the hard clay is discussed in detail. The hard clay in Chenghu mainly consists of fine silt, medium silt and clay; the content of fine silt from 26.7% to 38.1%, that of medium silt from 26.9% to 34.3%, that of clay from 19.7% to 26.2%, which belongs to clayey silt. The 10~50 μm particle group is the “dominate group” of the hard clay in Chenghu with the average content of 57.9%. The mean particlesize is from 6.3 to 6.9. Through the comparison of the particlesize characteristics among the hard clay in Chenghu, lake sediments, Xiashu Loess in Zhenjiang of Jiangsu Province and the northern China loesses in Qaidam, western Gansu, eastern Gansu, northern Shaanxi, western Shanxi and Shandong Province, we tend to conclude that the hard clay in Chenghu is of aeolian origin.
2008, 26(5): 844-849.
Abstract:
Element analysis combining with TOC and particle size test, cluster analysis and correlation analysis were applied to the study of surface sediments samples , which were collected from the Midreach of Wanchuan River near the Shuangdianzi Town of Lanzhou City , in order to reveal the geochemistry characteristics of heavy metals, such as distribution, removal and enrichment ,in surface depositional environment. According to this result, only element Zn was in lowgrade infectant. Correlation analysis indicated that there were no relation between heavy metal and particle size. Heavy metals transfered into sediments mainly from solidliquid system by multiphase chemical reaction. As a result of the input of paper making wastewater the contents of TOC in midupside of sampling river were higher. And due to the big molecule of organic matter, particle size in midupside of sampling river became bigger. TOC could weaken the enrichment of heavy metals.
Element analysis combining with TOC and particle size test, cluster analysis and correlation analysis were applied to the study of surface sediments samples , which were collected from the Midreach of Wanchuan River near the Shuangdianzi Town of Lanzhou City , in order to reveal the geochemistry characteristics of heavy metals, such as distribution, removal and enrichment ,in surface depositional environment. According to this result, only element Zn was in lowgrade infectant. Correlation analysis indicated that there were no relation between heavy metal and particle size. Heavy metals transfered into sediments mainly from solidliquid system by multiphase chemical reaction. As a result of the input of paper making wastewater the contents of TOC in midupside of sampling river were higher. And due to the big molecule of organic matter, particle size in midupside of sampling river became bigger. TOC could weaken the enrichment of heavy metals.
2008, 26(5): 850-856.
Abstract:
By the study of characteristics of internal structure and transporting pathways in fault, The main transporting pathways of fault in the stillstand period were considered to be the connected pores of kataclasite. The existence or not of their transporting oilgas ability was decided by the big or small of grain size of kataclasite, mudstone content of kataclasite and tip angle of fault. Based on it, the relation between oilgas migration velocity through kataclasite of fault under the action of buoyancy and grain size of kataclasite, mudstone content of kataclasite and tip angle of fault were studied by the physical simulation experiment. By the relation a method judging the existence or not of transporting oilgas ability of fault was established. If the oilgas migration velocity is more than zero, fault has transporting oilgas ability, on the contrary , fault don't have transporting oilgas ability . The method was applied in judging the existence or not of transporting oilgas ability of Surennuoer fault in different state of Hailaer Basin. The results accord with actual geological conditions. It indicates that the method is practical to judge quantitatively the existence or not of transporting oilgas ability of fault.
By the study of characteristics of internal structure and transporting pathways in fault, The main transporting pathways of fault in the stillstand period were considered to be the connected pores of kataclasite. The existence or not of their transporting oilgas ability was decided by the big or small of grain size of kataclasite, mudstone content of kataclasite and tip angle of fault. Based on it, the relation between oilgas migration velocity through kataclasite of fault under the action of buoyancy and grain size of kataclasite, mudstone content of kataclasite and tip angle of fault were studied by the physical simulation experiment. By the relation a method judging the existence or not of transporting oilgas ability of fault was established. If the oilgas migration velocity is more than zero, fault has transporting oilgas ability, on the contrary , fault don't have transporting oilgas ability . The method was applied in judging the existence or not of transporting oilgas ability of Surennuoer fault in different state of Hailaer Basin. The results accord with actual geological conditions. It indicates that the method is practical to judge quantitatively the existence or not of transporting oilgas ability of fault.
2008, 26(5): 864-871.
Abstract:
Based on the analysis and induction of the organic geochemical characteristics of the potential source rocks as well as the test results of the oil samples, the source of oils in Yongjin area was first systematically studied mainly using the indications of biomarker and stable carbon isotope. It is considered that the oils in Yongjin area were mainly generated from the midPermian and midtolowerJurassic source rocks, partly from the lowerPermian source rock, and potentially from the Cretaceous source rock. In detail, the normal oils in the container beds of midJurassic's Xishanyao Formation which are above the coal layer, as well as in the most Cretaceous container beds, mainly came from the midPermian source rock; the normal oils in the container beds of midJurassic's Xishanyao Formation which are beneath the coal layer, as well as in the container beds of lower Jurassic Sangonghe Formation, mainly came from the midtolower Jurassic source rock; the oils, which account for a small proportion in the pool and experienced serious biodegradation, came from the lowerPermian source rock; and the oil in the Cretaceous container rock of Well Yong 6 probably came from the lowerCretaceous source rock, but the hydrocarbonsupplying power of this source rock may be weak.
Based on the analysis and induction of the organic geochemical characteristics of the potential source rocks as well as the test results of the oil samples, the source of oils in Yongjin area was first systematically studied mainly using the indications of biomarker and stable carbon isotope. It is considered that the oils in Yongjin area were mainly generated from the midPermian and midtolowerJurassic source rocks, partly from the lowerPermian source rock, and potentially from the Cretaceous source rock. In detail, the normal oils in the container beds of midJurassic's Xishanyao Formation which are above the coal layer, as well as in the most Cretaceous container beds, mainly came from the midPermian source rock; the normal oils in the container beds of midJurassic's Xishanyao Formation which are beneath the coal layer, as well as in the container beds of lower Jurassic Sangonghe Formation, mainly came from the midtolower Jurassic source rock; the oils, which account for a small proportion in the pool and experienced serious biodegradation, came from the lowerPermian source rock; and the oil in the Cretaceous container rock of Well Yong 6 probably came from the lowerCretaceous source rock, but the hydrocarbonsupplying power of this source rock may be weak.
2008, 26(5): 881-885.
Abstract:
Exploration and development of lithologic oilgas reservoirs are important directions and hot research areas. Zhu1 Depression of Pearl River Mouth Basin has an annual crude oil output over 10 million tons,but the industrial value of the reservoir has not been found in subtectonic units:Enping Depression. In lower Tertiary Wenchang Formation in Enping Depression, there is a set of turbidite sand with 300 meters thickness and 140 km2 area and up and down it are halfdeep to deep lacustrine sedimentary facies fine sediments.Geological and geochemical study shows that the main hydrocarbon source rocks from Wenchang Formation developed well and there is the condition to form lithologic Oilgas reservoirs. Based on seismic data, combined geological and logging technology, hydrocarbon potential of turbidite has been comprehensively analyzed in Enping Depression from Lower Tertiary Wenchang Formation. Seismic information indicates that the turdibite has a low frequency energy boost up and high frequency energy depressed character; AVO anomaly in the same time, inphase axes descend in the below of the turdibite. Well EP1731 is the margin of the turdibite, an anomaly high pressure has been detected in the 45524642 meters depth. All the above shows oilgas bearing character. So, the turdibite is a favorable exploration object and of the hope for the exploration and development of oilgas reservoirs in Enping Depression.
Exploration and development of lithologic oilgas reservoirs are important directions and hot research areas. Zhu1 Depression of Pearl River Mouth Basin has an annual crude oil output over 10 million tons,but the industrial value of the reservoir has not been found in subtectonic units:Enping Depression. In lower Tertiary Wenchang Formation in Enping Depression, there is a set of turbidite sand with 300 meters thickness and 140 km2 area and up and down it are halfdeep to deep lacustrine sedimentary facies fine sediments.Geological and geochemical study shows that the main hydrocarbon source rocks from Wenchang Formation developed well and there is the condition to form lithologic Oilgas reservoirs. Based on seismic data, combined geological and logging technology, hydrocarbon potential of turbidite has been comprehensively analyzed in Enping Depression from Lower Tertiary Wenchang Formation. Seismic information indicates that the turdibite has a low frequency energy boost up and high frequency energy depressed character; AVO anomaly in the same time, inphase axes descend in the below of the turdibite. Well EP1731 is the margin of the turdibite, an anomaly high pressure has been detected in the 45524642 meters depth. All the above shows oilgas bearing character. So, the turdibite is a favorable exploration object and of the hope for the exploration and development of oilgas reservoirs in Enping Depression.
2008, 26(5): 891-895.
Abstract:
Saturated hydrocarbon of coal，carbonaceous mudstone and oils from the Lower Jurassic coal measures in the Turpan basin have been analyzed by GC/MS in this paper，and biomarker characteristics and coal thermal maturity analyzed to draw the following conclusions：There are many similar biomarker characteristics between oil from middlelower Jurassic of Turpan Basin and coal and carbonaceous mudstone in the same strata. They all contain specific rlupane, Inorbietane,C24tetracyclic and high content of C29steranes. These characteristics suggest that they should have similar matter source of the organic matter are derived from matter with abundant high plants. Meanwhile, biomarkers, often used to indicate depositional environments, is characterized by high Pr/Ph ratio, little or no gammacerane and high abundance dibenzofurans, such biomarker distributions are indicative of suboxic and freshwater environment. Although coal and carbonaceous mudstone〖KG1〗remain in lower thermal maturity (Ro=0.47~0.53), but C29ββ／（αα＋ββ）sterane ratio (0.2940.489) and bezohopane are detected in this study. Because these fearture are related to bacterial activity, so bacterial degradation of organic matter may play an important role in coalderived oil.
Saturated hydrocarbon of coal，carbonaceous mudstone and oils from the Lower Jurassic coal measures in the Turpan basin have been analyzed by GC/MS in this paper，and biomarker characteristics and coal thermal maturity analyzed to draw the following conclusions：There are many similar biomarker characteristics between oil from middlelower Jurassic of Turpan Basin and coal and carbonaceous mudstone in the same strata. They all contain specific rlupane, Inorbietane,C24tetracyclic and high content of C29steranes. These characteristics suggest that they should have similar matter source of the organic matter are derived from matter with abundant high plants. Meanwhile, biomarkers, often used to indicate depositional environments, is characterized by high Pr/Ph ratio, little or no gammacerane and high abundance dibenzofurans, such biomarker distributions are indicative of suboxic and freshwater environment. Although coal and carbonaceous mudstone〖KG1〗remain in lower thermal maturity (Ro=0.47~0.53), but C29ββ／（αα＋ββ）sterane ratio (0.2940.489) and bezohopane are detected in this study. Because these fearture are related to bacterial activity, so bacterial degradation of organic matter may play an important role in coalderived oil.
2008, 26(5): 725-729.
Abstract:
〖WT5HZ〗Abstract〖WTBZ〗〖KG1〗Paleosols were formed on the basis of the reconstruction of primary rocks in the pedogenic process during the long geologic period. The 4 types of Permian paleosols were developed in the southern part of Bogeda range based on the fine research of outcrop and the inside job. The histosol was located on the top of the paleosol section, resulted from the watery paleoenvironment. The argillisol was precipitated within the bottom of eluviation belt, resulted from the long eluviation and the moist ancient climate. The spodosol was characteristic of the ferruginous concentric ball due to the longterm eluviation and the dankish climatic environment. The calcisol was characteristic of the abundant calcic conglomeration from the halfarid to arid ancient climatic environment. The sequence cycles can be divided carefully and the ancient climatic environment can be recovered veraciously according to the paleosol section.
〖WT5HZ〗Abstract〖WTBZ〗〖KG1〗Paleosols were formed on the basis of the reconstruction of primary rocks in the pedogenic process during the long geologic period. The 4 types of Permian paleosols were developed in the southern part of Bogeda range based on the fine research of outcrop and the inside job. The histosol was located on the top of the paleosol section, resulted from the watery paleoenvironment. The argillisol was precipitated within the bottom of eluviation belt, resulted from the long eluviation and the moist ancient climate. The spodosol was characteristic of the ferruginous concentric ball due to the longterm eluviation and the dankish climatic environment. The calcisol was characteristic of the abundant calcic conglomeration from the halfarid to arid ancient climatic environment. The sequence cycles can be divided carefully and the ancient climatic environment can be recovered veraciously according to the paleosol section.
2008, 26(5): 737-743.
Abstract:
Guided with the theory of high resolution sequence stratigraphy and based on cores, well logs and seismic materials, the sequence stratigraphic scheme of the Member 4 Quantou Formation to Yaojia Formation in HaituoziDabusu area has been constructed, which is composed of 5 long term base level cycles (third order sequence) and 9 middle term base level cycles(fourth order sequence), and the sequence stratigraphic framework has been discussed. The result shows that turbidite sand body and distributary channels of delta front mainly develop at the half cycle increasing period and mouth bar, distal bar and sheet sand of delta front mainly develop at the half cycle decreasing period. The turbidite sand body and distal bar, sheet sand of delta front are favorable reservoirs in the study area.
Guided with the theory of high resolution sequence stratigraphy and based on cores, well logs and seismic materials, the sequence stratigraphic scheme of the Member 4 Quantou Formation to Yaojia Formation in HaituoziDabusu area has been constructed, which is composed of 5 long term base level cycles (third order sequence) and 9 middle term base level cycles(fourth order sequence), and the sequence stratigraphic framework has been discussed. The result shows that turbidite sand body and distributary channels of delta front mainly develop at the half cycle increasing period and mouth bar, distal bar and sheet sand of delta front mainly develop at the half cycle decreasing period. The turbidite sand body and distal bar, sheet sand of delta front are favorable reservoirs in the study area.
2008, 26(5): 753-761.
Abstract:
On the Basis of stratigraphic modelling using the SEDPAK computer program, the response of sequence stacking patterns to asymmetrical tectonic subsidence within a rift basin was simulated by considering the various parameters controlling the deposition of a sequence. The simulation results indicate that isochronous sequence stratigraphy within a rift basin may exhibit both synchronous and nonsynchronous stacking patterns at different part of the basin. Synchronous stacking patterns refer to that at any part of the basin the same transgression, retrogression and aggression occurs concurrently. Nonsynchronous stacking patterns refer to that within the same basin some part may exhibit the exact opposite stacking patterns as other parts concomitantly.
〓〓The development of nonsynchronous stacking patterns were found to be caused by the combination of both accommodation space increment（ΔA）more than sediment supply increment（ΔS）（ΔA＜ΔS）in one side of basin and accommodation space increment（ΔA）less than or equal to sediment supply increment （ΔS）（ΔA≥ΔS）in other sides of basin. Meanwhile, duration of nonsynchronous stacking patterns was controlled by the interplay of accommodation space increment（ΔA）and sediment supply increment（ΔS）.Recognition of nonsynchronous stacking patterns of isochronous sequence stratigraphy provides a new insight into continental sequence stratigraphy, and might be widely applicable for the Cenozoic basins in the eastern China.
On the Basis of stratigraphic modelling using the SEDPAK computer program, the response of sequence stacking patterns to asymmetrical tectonic subsidence within a rift basin was simulated by considering the various parameters controlling the deposition of a sequence. The simulation results indicate that isochronous sequence stratigraphy within a rift basin may exhibit both synchronous and nonsynchronous stacking patterns at different part of the basin. Synchronous stacking patterns refer to that at any part of the basin the same transgression, retrogression and aggression occurs concurrently. Nonsynchronous stacking patterns refer to that within the same basin some part may exhibit the exact opposite stacking patterns as other parts concomitantly.
〓〓The development of nonsynchronous stacking patterns were found to be caused by the combination of both accommodation space increment（ΔA）more than sediment supply increment（ΔS）（ΔA＜ΔS）in one side of basin and accommodation space increment（ΔA）less than or equal to sediment supply increment （ΔS）（ΔA≥ΔS）in other sides of basin. Meanwhile, duration of nonsynchronous stacking patterns was controlled by the interplay of accommodation space increment（ΔA）and sediment supply increment（ΔS）.Recognition of nonsynchronous stacking patterns of isochronous sequence stratigraphy provides a new insight into continental sequence stratigraphy, and might be widely applicable for the Cenozoic basins in the eastern China.
2008, 26(5): 772-779.
Abstract:
Seismites is a kind of catastrophic event rock. By the observation of drilling cores, there are many special structures which were generated by ancient widespread earthquake recorded in the seismites of the Triassic Yangchang Formation in Ordos Basin, such as liquefaction sandstone vein, faultgraded, vibrational liquefaction deformation structure, pillow structure, ball structure, tearing mudstone fragment and slumps. The vertical sequence of seismites in Triassic Yangchang Formation, from bottom to top, included 7 units: underlying unshocked layer, shattered layer, laddershaped faulted layer, vibrational liquefaction deformation structure bed，liquefied sandstone vein bed，pillow structure and partner structure layer，homogenized bed and overlying unshocked layer. The first discovery of seismites could be used to analyze the intensively active period of basincontrolling boundary, and the seismites themselves were a kind of potential reservoir.
Seismites is a kind of catastrophic event rock. By the observation of drilling cores, there are many special structures which were generated by ancient widespread earthquake recorded in the seismites of the Triassic Yangchang Formation in Ordos Basin, such as liquefaction sandstone vein, faultgraded, vibrational liquefaction deformation structure, pillow structure, ball structure, tearing mudstone fragment and slumps. The vertical sequence of seismites in Triassic Yangchang Formation, from bottom to top, included 7 units: underlying unshocked layer, shattered layer, laddershaped faulted layer, vibrational liquefaction deformation structure bed，liquefied sandstone vein bed，pillow structure and partner structure layer，homogenized bed and overlying unshocked layer. The first discovery of seismites could be used to analyze the intensively active period of basincontrolling boundary, and the seismites themselves were a kind of potential reservoir.
2008, 26(5): 789-796.
Abstract:
The density of debris flows is the most important parameter of debris flows. It is more important to get the density of debris flows with the need of the evaluation and prevention the hazards of debris flows. In this paper, the size of coarse particle, fine particle and clay of debris flows, i.e. 2mm, 0.05mm and 0.005mm, and their percentage were analyzed for the relationship with the density of debris flows. The percentages of coarse particle, fine particle and clay of debris flows have certain relationships with density of debris flows, but they are not the unique because the difference of region. The percentage of clay in viscous debris flows is the same with the percentage of clay in the solid source of debris flows, but the percentage of clay in less viscous debris flows is much more than the percentage of clay in the solid source of debris flows. Comparing the living samples and deposit samples of debris flows with the calculating density of debris flows by the percentages of coarse particle and fine particle, it is good consistency. But the calculating density of debris flows must obey the density range obtained by the characteristics of deposit of debris flows.
The density of debris flows is the most important parameter of debris flows. It is more important to get the density of debris flows with the need of the evaluation and prevention the hazards of debris flows. In this paper, the size of coarse particle, fine particle and clay of debris flows, i.e. 2mm, 0.05mm and 0.005mm, and their percentage were analyzed for the relationship with the density of debris flows. The percentages of coarse particle, fine particle and clay of debris flows have certain relationships with density of debris flows, but they are not the unique because the difference of region. The percentage of clay in viscous debris flows is the same with the percentage of clay in the solid source of debris flows, but the percentage of clay in less viscous debris flows is much more than the percentage of clay in the solid source of debris flows. Comparing the living samples and deposit samples of debris flows with the calculating density of debris flows by the percentages of coarse particle and fine particle, it is good consistency. But the calculating density of debris flows must obey the density range obtained by the characteristics of deposit of debris flows.
2008, 26(5): 804-812.
Abstract:
The Yellow River Delta superlobe in 111099 formed on a very shallow sea area. The thickness of the delta close to the coast line in 1855 is only 12 m. The delta front silt or interdistributary bay clayey silt accumulates on the prodelta. In the old delta deposits, the bioturbation structure can be observed, the mollusk shells are common, more foraminiferal tests and marine ostracod valves exist. They are different from those in North Jiangsu delta superlobe (11281855) and Modern Delta superlobe (since 1855). These indicate that the sedimentation rate in the old delta superlobe is lower than the other two younger delta superlobes and indirectly indicate the increasing erosion in the Loess Plateau.
The Yellow River Delta superlobe in 111099 formed on a very shallow sea area. The thickness of the delta close to the coast line in 1855 is only 12 m. The delta front silt or interdistributary bay clayey silt accumulates on the prodelta. In the old delta deposits, the bioturbation structure can be observed, the mollusk shells are common, more foraminiferal tests and marine ostracod valves exist. They are different from those in North Jiangsu delta superlobe (11281855) and Modern Delta superlobe (since 1855). These indicate that the sedimentation rate in the old delta superlobe is lower than the other two younger delta superlobes and indirectly indicate the increasing erosion in the Loess Plateau.
2008, 26(5): 820-827.
Abstract:
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〖WT5HZ〗Abstract〓〖WTBZ〗The values of pH and Eh (OxidationReduction Potential) of the surface sediments in the Yangtze River estuary and its adjacent areas were determined with a precision acidimeter (pH meter) and a ORP meter. The space distributions of pH and Eh of the sediments in these areas are figured out and their influence factors are systematically discussed. The results indicate that the surface sedimentary environment in the study areas is neutral or weak alkaline with pH value ranging from 7.1 to 7.8. The distribution of pH value in the area is zonal and heterogeneous. The redox in the area is reductive with Eh ranging from 300mv to 100mV and mostly ranging around 250mV. Distribution of Eh in the area also seems zonal and heterogeneous. The value of pH in these areas is mainly dominated by the natures of water masses as well as grained size of sediment and patterns of bioturbation. While the natures water masses, water stratification, and patterns of bioturbation are the controlling factors of Eh in these areas.
00)
〖WT5HZ〗Abstract〓〖WTBZ〗The values of pH and Eh (OxidationReduction Potential) of the surface sediments in the Yangtze River estuary and its adjacent areas were determined with a precision acidimeter (pH meter) and a ORP meter. The space distributions of pH and Eh of the sediments in these areas are figured out and their influence factors are systematically discussed. The results indicate that the surface sedimentary environment in the study areas is neutral or weak alkaline with pH value ranging from 7.1 to 7.8. The distribution of pH value in the area is zonal and heterogeneous. The redox in the area is reductive with Eh ranging from 300mv to 100mV and mostly ranging around 250mV. Distribution of Eh in the area also seems zonal and heterogeneous. The value of pH in these areas is mainly dominated by the natures of water masses as well as grained size of sediment and patterns of bioturbation. While the natures water masses, water stratification, and patterns of bioturbation are the controlling factors of Eh in these areas.
2008, 26(5): 833-843.
Abstract:
Based on the data of two tidal flat profiles, surface sediment and suspended sediment grainsize, current velocity and suspended sediment concentration in the east Chongming tidal flat, the sediment and geomorphology differentiation of tidal flat profiles combined wave and current actions were analyzed. The results showed that the surface sediment D50 decreased gradually from the surf zone to the near shore and outer sea. The sorting of the surface sediment increased, and the skewness changed from very positive to positive, and the kurtosis changed from very leptokurtic to platykurtic and mesokurtic. The current velocity decreased and the suspended sediment concentration increased from the surf zone to the near shore. The comparative analysis of suspended and surfacial sediment grain size showed that the suspended sediment in the upper of intertidal zone mainly came from the sediment resuspension of the surf zone. The selective transport due to the sediment uplift by wave dominated the sediment transport in the surf zone, and the sediment horizontal transport by tidal current dominated the sediment transport in the near shore and outer sea beside the surf zone. The microgeomorphic units of east Chongming tidal flat were divided based on the discussion of the water level and accurate elevation recently.
Based on the data of two tidal flat profiles, surface sediment and suspended sediment grainsize, current velocity and suspended sediment concentration in the east Chongming tidal flat, the sediment and geomorphology differentiation of tidal flat profiles combined wave and current actions were analyzed. The results showed that the surface sediment D50 decreased gradually from the surf zone to the near shore and outer sea. The sorting of the surface sediment increased, and the skewness changed from very positive to positive, and the kurtosis changed from very leptokurtic to platykurtic and mesokurtic. The current velocity decreased and the suspended sediment concentration increased from the surf zone to the near shore. The comparative analysis of suspended and surfacial sediment grain size showed that the suspended sediment in the upper of intertidal zone mainly came from the sediment resuspension of the surf zone. The selective transport due to the sediment uplift by wave dominated the sediment transport in the surf zone, and the sediment horizontal transport by tidal current dominated the sediment transport in the near shore and outer sea beside the surf zone. The microgeomorphic units of east Chongming tidal flat were divided based on the discussion of the water level and accurate elevation recently.
2008, 26(5): 857-863.
Abstract:
The low temperature pyrolysis for coal and mudstone samples collected from Well AS1 in TurpanHami basin was carried out in the closed system with goldtube autovlaves. The initial kinetic parameters of dry and wet gases generation are calculated according to the pyrolysis data. Then the kinetic parameters of single activation energy are further optimized into Gaussian distribution of activation energies, which is better to fit empirical data. The optimized kinetic parameters are applied to modeling the early gas generation of Badaowan Formation in Qiudong subsag, TurpanHami basin, which shows that the modeling results match well with the geological process of early natural gas generation; the isothermal pyrolysis at low temperature is an effectual way to evaluate the early gas generation; the natural gas discovered in Qiudong subsag is closely associated with the source rocks of the Badaowan Formation.
The low temperature pyrolysis for coal and mudstone samples collected from Well AS1 in TurpanHami basin was carried out in the closed system with goldtube autovlaves. The initial kinetic parameters of dry and wet gases generation are calculated according to the pyrolysis data. Then the kinetic parameters of single activation energy are further optimized into Gaussian distribution of activation energies, which is better to fit empirical data. The optimized kinetic parameters are applied to modeling the early gas generation of Badaowan Formation in Qiudong subsag, TurpanHami basin, which shows that the modeling results match well with the geological process of early natural gas generation; the isothermal pyrolysis at low temperature is an effectual way to evaluate the early gas generation; the natural gas discovered in Qiudong subsag is closely associated with the source rocks of the Badaowan Formation.
2008, 26(5): 872-880.
Abstract:
From the angel of paleoclimate and paleooceangraphy, combined with Paleozoic paleogeography characters, the developmental controlling factors of Upper Ordovician Lower Silurian high quality source rocks in marine sequence, South China were discussed in this paper, with analysis of geochemical data in typical section from upper Yangtze. The researches indicate geochemical indicators such as V/（V+Ni）, Ni/Co, Ceanom, δEu and δ13Corg have good relationship with the content of organic carbon, and the abnormal of these indicators illustrate that the high quality source rocks of Upper Ordovician Lower Silurian were developed in anoxic environment. However, from the researches of paleoclimate and paleooceangraphy, the developmental controlling factors of Wufeng Formation in Upper Ordovician are different with those of Longmaxi Formation in Lower Silurian. As the ice age reached its crest in Wufeng period, the intense upper welling formed in Yangtze area, which improved the organic production. The thin argillite with high abundance of organic matter covered in Yangtze area are the best indicators of upper welling. The global paleoclimate came into a warm period as Longmaxi Formation deposit, which were disadvantage for lager scale upper welling. In this period, the effects of upper welling were limited in deep slope around Yangtze craton. High quality source rocks of Longmaxi Formation were developed in early period of transgression. Because during initial transgression, coarsergrained siliciclastics are constrained to fill, and the anoxic environment were preserved. During latter transgression, as the deep water and surface water have abundance time to mix, the anoxic environment were destroyed in deep sea, as a result of which, the preservation condition of organic matter become bad.
From the angel of paleoclimate and paleooceangraphy, combined with Paleozoic paleogeography characters, the developmental controlling factors of Upper Ordovician Lower Silurian high quality source rocks in marine sequence, South China were discussed in this paper, with analysis of geochemical data in typical section from upper Yangtze. The researches indicate geochemical indicators such as V/（V+Ni）, Ni/Co, Ceanom, δEu and δ13Corg have good relationship with the content of organic carbon, and the abnormal of these indicators illustrate that the high quality source rocks of Upper Ordovician Lower Silurian were developed in anoxic environment. However, from the researches of paleoclimate and paleooceangraphy, the developmental controlling factors of Wufeng Formation in Upper Ordovician are different with those of Longmaxi Formation in Lower Silurian. As the ice age reached its crest in Wufeng period, the intense upper welling formed in Yangtze area, which improved the organic production. The thin argillite with high abundance of organic matter covered in Yangtze area are the best indicators of upper welling. The global paleoclimate came into a warm period as Longmaxi Formation deposit, which were disadvantage for lager scale upper welling. In this period, the effects of upper welling were limited in deep slope around Yangtze craton. High quality source rocks of Longmaxi Formation were developed in early period of transgression. Because during initial transgression, coarsergrained siliciclastics are constrained to fill, and the anoxic environment were preserved. During latter transgression, as the deep water and surface water have abundance time to mix, the anoxic environment were destroyed in deep sea, as a result of which, the preservation condition of organic matter become bad.
2008, 26(5): 886-890.
Abstract:
Fatty acid ester is a kind of important hydrocarbon source matter. In this paper, the mixture of tetradecanoic acid methyl ester, palmitic acid methyl ester and methyl stearate were chosen as the model reactant. Calcite, dolomite, illite, Camontmorillonite and pyrite were chosen as catalyst. The effects of potassium chloride, magnesium chloride, sodium chloride, sodium sulfate and mixed salt on the hydrocarbon generation of mixed ester were investigated. The results show that the effects of inorganic salts on the hydrocarbon generation from mixed ester catalyzed by minerals are different. Sodium sulfate exhibit inhibition effects and the other salts promote the hydrocarbon generation. And it has the different catalytic activities with the different minerals in the presence of inorganic salts.
Fatty acid ester is a kind of important hydrocarbon source matter. In this paper, the mixture of tetradecanoic acid methyl ester, palmitic acid methyl ester and methyl stearate were chosen as the model reactant. Calcite, dolomite, illite, Camontmorillonite and pyrite were chosen as catalyst. The effects of potassium chloride, magnesium chloride, sodium chloride, sodium sulfate and mixed salt on the hydrocarbon generation of mixed ester were investigated. The results show that the effects of inorganic salts on the hydrocarbon generation from mixed ester catalyzed by minerals are different. Sodium sulfate exhibit inhibition effects and the other salts promote the hydrocarbon generation. And it has the different catalytic activities with the different minerals in the presence of inorganic salts.
