2009 Vol. 27, No. 1
Display Method:
2009, 27(1): 1-8.
Abstract:
The Feixianguan Formation of Lower Triassic in the northeast Sichuan can be divided into 2 thirdorder sequences, six system tracts in terms of sedimentary facies and sequence interfaces. Characteristics of sequence stratigraphy of the Feixianguan Formation are analyzed, sequence palaeogeography maps compiled and development regularity of oolitic shoal predicted. It is indicated that, during the development of SQ1 sequence, the effect of transgression brings about such distribution framework of facies zones as platform basinplatform marginopenlimitedevaporate platform. Of the system tracts, the platform margin and oolitic shoal are the most developed ones. The effects of large scale descent of sea level and dry and hot climate during the development stage of SQ2 translates the original open platform into limited one and eventually into evaporate platform with dominant deposition of dolomite, forming the first important regional tight caprock of the Feixianguan Formation which is favorable for the accumulation of oil and gas.
The Feixianguan Formation of Lower Triassic in the northeast Sichuan can be divided into 2 thirdorder sequences, six system tracts in terms of sedimentary facies and sequence interfaces. Characteristics of sequence stratigraphy of the Feixianguan Formation are analyzed, sequence palaeogeography maps compiled and development regularity of oolitic shoal predicted. It is indicated that, during the development of SQ1 sequence, the effect of transgression brings about such distribution framework of facies zones as platform basinplatform marginopenlimitedevaporate platform. Of the system tracts, the platform margin and oolitic shoal are the most developed ones. The effects of large scale descent of sea level and dry and hot climate during the development stage of SQ2 translates the original open platform into limited one and eventually into evaporate platform with dominant deposition of dolomite, forming the first important regional tight caprock of the Feixianguan Formation which is favorable for the accumulation of oil and gas.
2009, 27(1): 18-25.
Abstract:
The sedimentary character and facies model of the upper member of Guantao Formation in Xinbei oilfield of Shengli petroleum province were studied by core observation, granularity analysis, parameters count and well log analysis mainly. It's showed that the aim stratum in the studied area is the anabranched channel. Its granularity probability cumulation curves show similar character with the braided stream. The average channel sinuosity is more than 1.7 and duality structure develops, which is similar to meandering river. The developed burst fans can distinguish it with anastomosing river. The anabranched channel model in the studied area includes four subfacies, such as channel, bank, overflow and abandoned channel. The channel bars in abandoned channel subfacies are the most important sedimentary body. The burst fans and abandoning channels are more developed than that of natural levees. The top of the channel bars are often covered by flood plain successively. The distribution of petroleum in Xinbei oilfield is controlled by the anabranched channel mainly. The discovery of the anabranched channel facies can help Xinbei oilfield's fine sand body forecast and optimizing exploitation plan, and can be a useful geologic model for the reservoir forecast in other similar areas.
The sedimentary character and facies model of the upper member of Guantao Formation in Xinbei oilfield of Shengli petroleum province were studied by core observation, granularity analysis, parameters count and well log analysis mainly. It's showed that the aim stratum in the studied area is the anabranched channel. Its granularity probability cumulation curves show similar character with the braided stream. The average channel sinuosity is more than 1.7 and duality structure develops, which is similar to meandering river. The developed burst fans can distinguish it with anastomosing river. The anabranched channel model in the studied area includes four subfacies, such as channel, bank, overflow and abandoned channel. The channel bars in abandoned channel subfacies are the most important sedimentary body. The burst fans and abandoning channels are more developed than that of natural levees. The top of the channel bars are often covered by flood plain successively. The distribution of petroleum in Xinbei oilfield is controlled by the anabranched channel mainly. The discovery of the anabranched channel facies can help Xinbei oilfield's fine sand body forecast and optimizing exploitation plan, and can be a useful geologic model for the reservoir forecast in other similar areas.
2009, 27(1): 32-40.
Abstract:
Taking the 4th member of Cretaceous Quantou Formation in Dalaoyefu oilfield in Songliao Basin as Example, by using the shortterm baselevel cycle theory of high resolution sequence stratigraphy, the paper shows the variety of genetic assemblages of reservoir rocks in delta front depositional system that was dominated by the distributary channel and mouth bar. It can be classified as “distributary channel genetic assemblage” “distributary channel and mouth bar hybrid genetic assemblage” and “mouth bars genetic assemblage”. Based on a detailed characterization of these genetic assemblages, the abundant genetic assemblage can reflect different sedimentary environments, for example, submerged distributary channels genetic assemblage are divided into Abandoned Type, Integrity Type and Multiphase Overprint Type; mouth bar genetic assemblage can be divided into Complete Mouth Bar and Stackmouth Bar, and the hybrid genetic assemblage is identified. The analysis shows that these sandbodies are evidently controlled by the changing of shortterm baselevel and the relation of the accompanied accommodation and sediment alimentations. On the basis of the above, this paper has also discussed the distribution model of the genetic assemblages in delta front in chronostratigraphic framework.
Taking the 4th member of Cretaceous Quantou Formation in Dalaoyefu oilfield in Songliao Basin as Example, by using the shortterm baselevel cycle theory of high resolution sequence stratigraphy, the paper shows the variety of genetic assemblages of reservoir rocks in delta front depositional system that was dominated by the distributary channel and mouth bar. It can be classified as “distributary channel genetic assemblage” “distributary channel and mouth bar hybrid genetic assemblage” and “mouth bars genetic assemblage”. Based on a detailed characterization of these genetic assemblages, the abundant genetic assemblage can reflect different sedimentary environments, for example, submerged distributary channels genetic assemblage are divided into Abandoned Type, Integrity Type and Multiphase Overprint Type; mouth bar genetic assemblage can be divided into Complete Mouth Bar and Stackmouth Bar, and the hybrid genetic assemblage is identified. The analysis shows that these sandbodies are evidently controlled by the changing of shortterm baselevel and the relation of the accompanied accommodation and sediment alimentations. On the basis of the above, this paper has also discussed the distribution model of the genetic assemblages in delta front in chronostratigraphic framework.
2009, 27(1): 48-56.
Abstract:
Sedimentary sequence which belongs to the second grade sequence locates among the parallel, microangular or angular unconformities, and which is divided into 3 second order sequences, 13 third order sequences and numeral fourth or fifth order sequences. There are three series of sedimentary cycles for transgression to regression, and identifying alluvial fanfluvial facies, lakedelta and fluvial facies and so on. Structure, climate, sedimentary supply and variation in lake level and so on control the depositional architecture of the Paleogene System tectonic sequences and their response to tectonism in Jizhong depression. The analysis shows that the depression suffers for two sets of evolvement gyrations attributing to variation in deposition rate. Phase 1, slowness accelerating subsidence at Paleocene in Paleogene Period, earlymediumterm speediness subsidence at Eocene Epoch and terminal slowness subsidence at Eocene Epoch. Phase 2, telophase lowness accelerating subsidence at Eocene Epoch, earlyterm speediness subsidence at Oligocene and mediumterminal slowness subsidence accelerating subsidence at Oligocene. Settlement rate partly is 100～110 m·Ma1, 205～220 m·Ma1, 40～50 m·Ma1,30～40 m·Ma1, 135～142 m·Ma1 and 10～20 m·Ma1. Wring action in Paleogene Period shows sinistral movement makes enechelon structure as causes NNE or NE orient distribution at terminal of Sha4 and Dongying member, and dextral movement is reverse. At last the depression unfolds the structure of two sunkens champing one convex.
Sedimentary sequence which belongs to the second grade sequence locates among the parallel, microangular or angular unconformities, and which is divided into 3 second order sequences, 13 third order sequences and numeral fourth or fifth order sequences. There are three series of sedimentary cycles for transgression to regression, and identifying alluvial fanfluvial facies, lakedelta and fluvial facies and so on. Structure, climate, sedimentary supply and variation in lake level and so on control the depositional architecture of the Paleogene System tectonic sequences and their response to tectonism in Jizhong depression. The analysis shows that the depression suffers for two sets of evolvement gyrations attributing to variation in deposition rate. Phase 1, slowness accelerating subsidence at Paleocene in Paleogene Period, earlymediumterm speediness subsidence at Eocene Epoch and terminal slowness subsidence at Eocene Epoch. Phase 2, telophase lowness accelerating subsidence at Eocene Epoch, earlyterm speediness subsidence at Oligocene and mediumterminal slowness subsidence accelerating subsidence at Oligocene. Settlement rate partly is 100～110 m·Ma1, 205～220 m·Ma1, 40～50 m·Ma1,30～40 m·Ma1, 135～142 m·Ma1 and 10～20 m·Ma1. Wring action in Paleogene Period shows sinistral movement makes enechelon structure as causes NNE or NE orient distribution at terminal of Sha4 and Dongying member, and dextral movement is reverse. At last the depression unfolds the structure of two sunkens champing one convex.
2009, 27(1): 64-69.
Abstract:
This article established the 1D quantitative theoretical model of base level cycle of sinusoidal curve stratigraphy from the view of fluvial hydrodynamics on the basic of summarizing the notion of base level. The modeling simulated the change of strata surface and sediment of strata, erosion and hungry deposition .the stratigraphic is established and recovered. All the simulation made by modeling the basic data such as sediment velocity，curve shape of base level cycle，curve of sediment supply velocity，average radius and density of silt, etc. Analysis the modeling according the given parameter, discussed the different stratigraphic pattern which generate when baselevel intersect with strata surface. At last, according the contrast the three types of steady strata when the strata surface higher，lower，equal the base level , we can conclude that the balance broken because of the strata surface declined mutation.
This article established the 1D quantitative theoretical model of base level cycle of sinusoidal curve stratigraphy from the view of fluvial hydrodynamics on the basic of summarizing the notion of base level. The modeling simulated the change of strata surface and sediment of strata, erosion and hungry deposition .the stratigraphic is established and recovered. All the simulation made by modeling the basic data such as sediment velocity，curve shape of base level cycle，curve of sediment supply velocity，average radius and density of silt, etc. Analysis the modeling according the given parameter, discussed the different stratigraphic pattern which generate when baselevel intersect with strata surface. At last, according the contrast the three types of steady strata when the strata surface higher，lower，equal the base level , we can conclude that the balance broken because of the strata surface declined mutation.
2009, 27(1): 77-86.
Abstract:
It has been challenged for the sedimentological theories, such as “Bouma Sequence” and “turbidite fan”, in the direction of deepsea oilgas exploration. This is because, as Shanmugam et al. say, the “Bouma Sequence” is not a unique product of turbidity sedimentation, but results from cooperation of several sedimentation, i.e., sandy debris flow, turbidity current, internal tide and wave, contour current. Following the interpretation by Shanmugam et al., it is summarized as: sediments of the “Bouma Sequence” section A could be caused by sandy debris flow besides of turbidity current, those with crossbeddings within the sections BD be traction current; only those by turbidity current could be called turbidite; socalled “high density turbidity” is not real turbidity but sandy debris flow; turbidity current is Newton current and turbulent sediment gravity flow; there are no suspended layer and reverse grading within turbidite. It lacks linkage for deepsea traction current between theory and practice although advances have been made. And as an aspect of sedimentation, deepsea sequence stratigraphy is to some degree different from that in shallow sea：there are at least three types of sequence boundaries——slope erosional surface, downlap surface of lowstand systems tracts (LST), and submarine sediment hiatus surface; when it is dominated by a terrigenous depositional setting, LSTs would be composed of submarine fan sediments, transgressive systems tracts (TSTs) and early highstand systems tracts (HSTs) are probably of noncalcareous pelagic sediments, and few HSTs are found; when it becomes carbonate setting, LSTs are dominant of slump and debris sediments, TSTs and early HSTs could spread on submarine fan, and late HSTs could be consisted of calciturbidites. Support remarks and suggestions are proposed by review and experienced works of deepsea sedimentation: it would be better to invert comma “Bouma Sequence” to make a mark showing a note of notunique causal turbidite result; it is necessary to use the term “submarine fan” and/or "deepsea fan instead of “turbidite fan”; study of both theoretic deepsea traction currents (e.g. internal tide and wave, contourite) and practical field needs to promote in future. It is great potential and prosperous for oilgas exploration in deepsea sediment, especially for reservoir prediction of LST turbidite, sandy debris and bottom traction sandy bodies. However, to get a new burst in deepsea oilgas exploration, a key is that more precise and detailed study on theory of deepsea sedimentation and depositional procession would be engaged in future.
It has been challenged for the sedimentological theories, such as “Bouma Sequence” and “turbidite fan”, in the direction of deepsea oilgas exploration. This is because, as Shanmugam et al. say, the “Bouma Sequence” is not a unique product of turbidity sedimentation, but results from cooperation of several sedimentation, i.e., sandy debris flow, turbidity current, internal tide and wave, contour current. Following the interpretation by Shanmugam et al., it is summarized as: sediments of the “Bouma Sequence” section A could be caused by sandy debris flow besides of turbidity current, those with crossbeddings within the sections BD be traction current; only those by turbidity current could be called turbidite; socalled “high density turbidity” is not real turbidity but sandy debris flow; turbidity current is Newton current and turbulent sediment gravity flow; there are no suspended layer and reverse grading within turbidite. It lacks linkage for deepsea traction current between theory and practice although advances have been made. And as an aspect of sedimentation, deepsea sequence stratigraphy is to some degree different from that in shallow sea：there are at least three types of sequence boundaries——slope erosional surface, downlap surface of lowstand systems tracts (LST), and submarine sediment hiatus surface; when it is dominated by a terrigenous depositional setting, LSTs would be composed of submarine fan sediments, transgressive systems tracts (TSTs) and early highstand systems tracts (HSTs) are probably of noncalcareous pelagic sediments, and few HSTs are found; when it becomes carbonate setting, LSTs are dominant of slump and debris sediments, TSTs and early HSTs could spread on submarine fan, and late HSTs could be consisted of calciturbidites. Support remarks and suggestions are proposed by review and experienced works of deepsea sedimentation: it would be better to invert comma “Bouma Sequence” to make a mark showing a note of notunique causal turbidite result; it is necessary to use the term “submarine fan” and/or "deepsea fan instead of “turbidite fan”; study of both theoretic deepsea traction currents (e.g. internal tide and wave, contourite) and practical field needs to promote in future. It is great potential and prosperous for oilgas exploration in deepsea sediment, especially for reservoir prediction of LST turbidite, sandy debris and bottom traction sandy bodies. However, to get a new burst in deepsea oilgas exploration, a key is that more precise and detailed study on theory of deepsea sedimentation and depositional procession would be engaged in future.
2009, 27(1): 94-103.
Abstract:
The start time of the Asian interior aridification and East Asian monsoon is a research hotspot. The quartz sand grains which are taken from the Eogene red sandstones in the northern margin of Tibet Plateau were examined under Electronic Scanning Microscope for their external morphological characteristics in the paper. The result shows that the samples almost have the texture of subaqueous polished surface and Vshape impact pits which is the typical feature of hydraulic action, and it is obviously different with the quartz sands from modern sand dunes of Taklimakan and northern margin of Altun Mountain. Also, the variations of the grain size indicate the Eogene red sandstones are different from the loess and modern sand dunes. To combine the sedimentary characteristics, we conclude that it does not widely present aeolian sediments in the northern margin of Tibet Plateau, and the Asian interior aridification and East Asian monsoon not started during the Eeogene. The aridity of Western China may be controlled by the planet wind system and global cooling during Eogene.
The start time of the Asian interior aridification and East Asian monsoon is a research hotspot. The quartz sand grains which are taken from the Eogene red sandstones in the northern margin of Tibet Plateau were examined under Electronic Scanning Microscope for their external morphological characteristics in the paper. The result shows that the samples almost have the texture of subaqueous polished surface and Vshape impact pits which is the typical feature of hydraulic action, and it is obviously different with the quartz sands from modern sand dunes of Taklimakan and northern margin of Altun Mountain. Also, the variations of the grain size indicate the Eogene red sandstones are different from the loess and modern sand dunes. To combine the sedimentary characteristics, we conclude that it does not widely present aeolian sediments in the northern margin of Tibet Plateau, and the Asian interior aridification and East Asian monsoon not started during the Eeogene. The aridity of Western China may be controlled by the planet wind system and global cooling during Eogene.
2009, 27(1): 104-110.
Abstract:
Based on high resolution seismic profiles surface of offshore 1 561 km nearby Qingdao, we discovered that there were multistage developed ancient river ways in this area and river sedimentary system was not well preserved in many stratums in the most of them only some of the river subfacies stratums are preserved. The character of river cross section to the east of 120°30′is relatively well preserved. The data of age measurement showed that these rivers were mostly formed 37 000～11 000 years ago, that the largest burial depth(from the bottom of modern sea to river bottom) of riverbed was about 32m and the usual burial depth was between 20～28 m and that the widest part of the river orientation was approximately 1 500 m. The river section can be divided into 6 types according to the present visible figures, which are watercourse developed with channel bar, flat base continuous multistage developed, steep narrow, asymmetric. This paper also includes the general analysis of formation mechanism of rivers and ancient geography environment.
Based on high resolution seismic profiles surface of offshore 1 561 km nearby Qingdao, we discovered that there were multistage developed ancient river ways in this area and river sedimentary system was not well preserved in many stratums in the most of them only some of the river subfacies stratums are preserved. The character of river cross section to the east of 120°30′is relatively well preserved. The data of age measurement showed that these rivers were mostly formed 37 000～11 000 years ago, that the largest burial depth(from the bottom of modern sea to river bottom) of riverbed was about 32m and the usual burial depth was between 20～28 m and that the widest part of the river orientation was approximately 1 500 m. The river section can be divided into 6 types according to the present visible figures, which are watercourse developed with channel bar, flat base continuous multistage developed, steep narrow, asymmetric. This paper also includes the general analysis of formation mechanism of rivers and ancient geography environment.
2009, 27(1): 118-127.
Abstract:
Based upon analysis of lithology, grainsize and AMS14C dating for Core EC2005, located in the mud area off the ZhejiangFujian coast in the inner shelf of the East China Sea, the paleoenvironmental evolution can be ascertained. The hydrodynamic conditions and sedimentary environment changed greatly which could have been an integrated result of the varieties of lacustrine water depth, sealevel and climatic changes. From the bottom 60.20 m to 41.00 m (17.3～13.1 ka BP), a lacustrine delta developed, which can be divided into three facies: prodelta, delta front and delta plain. The delta sediments are deduced to mainly from the local drainage area. The sea water arrived at the study area at 13.1 ka BP and a 41 m thick sediment formed from then on, which can be divided into three facies: foreshore, nearshore and shallow sea. The facies evolution was well corresponding to the sea level changes, the hydrodynamic conditions changed greatly also during this period. From 12.3 ka BP, the study area was influenced by ZhejiangFujian Coastal Current (ZFCC), and Yangtzederived materials had been transported southward from that time. Since 7.3 ka BP, the sedimentary environment is dominated by the ZFCC, and the homogeneous mud sedimentation began to form. The worldwide climatic events such as the Younger Dryas episode and the 8.2 ka event were well recorded in the core.
Based upon analysis of lithology, grainsize and AMS14C dating for Core EC2005, located in the mud area off the ZhejiangFujian coast in the inner shelf of the East China Sea, the paleoenvironmental evolution can be ascertained. The hydrodynamic conditions and sedimentary environment changed greatly which could have been an integrated result of the varieties of lacustrine water depth, sealevel and climatic changes. From the bottom 60.20 m to 41.00 m (17.3～13.1 ka BP), a lacustrine delta developed, which can be divided into three facies: prodelta, delta front and delta plain. The delta sediments are deduced to mainly from the local drainage area. The sea water arrived at the study area at 13.1 ka BP and a 41 m thick sediment formed from then on, which can be divided into three facies: foreshore, nearshore and shallow sea. The facies evolution was well corresponding to the sea level changes, the hydrodynamic conditions changed greatly also during this period. From 12.3 ka BP, the study area was influenced by ZhejiangFujian Coastal Current (ZFCC), and Yangtzederived materials had been transported southward from that time. Since 7.3 ka BP, the sedimentary environment is dominated by the ZFCC, and the homogeneous mud sedimentation began to form. The worldwide climatic events such as the Younger Dryas episode and the 8.2 ka event were well recorded in the core.
2009, 27(1): 137-141.
Abstract:
The terrace of Qingyi River is very development in Ya’an area. According to lithology, flat surface and granularity of gravel in this area, the gravel root in the upper reach of Qingyi River. The direction of ancient Qingyi River from northeast to east in Wanguchang area in Yangping area, the direction of modern Qingyi River is eastnortheast all the while, the velocity has the tendency which reduces gradually. According to the terraces dating and height above sea level from early Pleistocene to Holocene Epoch, seven times tectonic uplift have taken place in Ya’an area. In Wanguchang area, the biggest uplift scope reaches 85 m,the maximum uplift rate is 0.532 mm/a; in Yangping area ,the biggest uplift scope reaches 52 m,the maximum uplift rate is 1.25 mm/a.
The terrace of Qingyi River is very development in Ya’an area. According to lithology, flat surface and granularity of gravel in this area, the gravel root in the upper reach of Qingyi River. The direction of ancient Qingyi River from northeast to east in Wanguchang area in Yangping area, the direction of modern Qingyi River is eastnortheast all the while, the velocity has the tendency which reduces gradually. According to the terraces dating and height above sea level from early Pleistocene to Holocene Epoch, seven times tectonic uplift have taken place in Ya’an area. In Wanguchang area, the biggest uplift scope reaches 85 m,the maximum uplift rate is 0.532 mm/a; in Yangping area ,the biggest uplift scope reaches 52 m,the maximum uplift rate is 1.25 mm/a.
2009, 27(1): 147-152.
Abstract:
Supercritical fluid extraction method(SFEm) has been used for the purification of peat cellulose and the extracts were analyzed and determined by gas chromatographymass spectrometry. Series of methyl esters, ethyl esters and nalkanes as well as small amount of fatty acids were detected. Cmax of longchain nalkanes , being typical of oddtoeven carbon number predominance,are at C29,C31,C33.Most of the series of ethyl esters which have not been reported by far have characteristic of a distribution at high carbon number and distinct eventoodd carbon number predominance. All of this, to a certain extent, discloses the information of climatic condition and variation in the process of the formation of peat. Supercritical fluid extraction method is indicated to be capable of removing lipids successfully from peat cellulose, which is in favor of improving the accuracy of δ13C value in peat cellulose, and opens another new road for the application of SFEm in earth science.
Supercritical fluid extraction method(SFEm) has been used for the purification of peat cellulose and the extracts were analyzed and determined by gas chromatographymass spectrometry. Series of methyl esters, ethyl esters and nalkanes as well as small amount of fatty acids were detected. Cmax of longchain nalkanes , being typical of oddtoeven carbon number predominance,are at C29,C31,C33.Most of the series of ethyl esters which have not been reported by far have characteristic of a distribution at high carbon number and distinct eventoodd carbon number predominance. All of this, to a certain extent, discloses the information of climatic condition and variation in the process of the formation of peat. Supercritical fluid extraction method is indicated to be capable of removing lipids successfully from peat cellulose, which is in favor of improving the accuracy of δ13C value in peat cellulose, and opens another new road for the application of SFEm in earth science.
2009, 27(1): 153-163.
Abstract:
The marine strata in China is of old age and in high evolution period, and the potential of gas generated from highovermature source rocks is limited, but the gas exploration of this marine strata in Tarim, Sichuan and Ordos basin has greatly effective with large oil and gas fields constantly discovered. This paper brings up the successive gas generation machanism for the origin of deep marine gas, including three meanings of transformation of gas generation matter, replacement of gas generation time,and change of gas source kitchen. The gas source kitchen of dispersive liquid hydrocarbon inside of source rocks inherits the characteristics of original gas source kitchen, but the gas source kitchen of dispersive & concentrated liquid hydrocarbon outside of source rocks has occurred the spacial change comparing with original gas source kitchen. The above three liquid hydrocarbon can be cracked into gas at highover mature stage, but the latter is embeded flatter and its time of cracking and gas generation is later than the former, which makes for the late gas accumulations.
This paper creates expulsion oil rate plates of different organic matter abundance through simulation experiments of hydrocarbon generation and expulsion of different organic matter abundance and different lithology source rocks, providing the basis for the reasearch of allocation proportion and quantity of dispersive liquid hydrocarbon inside & outside of source rocks. This paper demonstrates the quantity, distribution and cracking degree of dispersive soluble organic materials of Palaeozoic strata in Tarim basin from the evaluating indicator S1 of hydrocarbon generating potential, heatorigin asphalt and the fluorescence characteristic of reserviors, and makes sure of the reality of successive gas generation of organic matter of Palaeozoic marine source rocks in Tarim basin, and also calculates the cracking gas quantity of dispersive soluble organic matter in middle and lower Cambrian of Tarim basin.The application of successive gas generation mechanism of organic matter can greatly increase the gas exploration potential and hopeness of palaeozoic strata in Tarim basin.
The marine strata in China is of old age and in high evolution period, and the potential of gas generated from highovermature source rocks is limited, but the gas exploration of this marine strata in Tarim, Sichuan and Ordos basin has greatly effective with large oil and gas fields constantly discovered. This paper brings up the successive gas generation machanism for the origin of deep marine gas, including three meanings of transformation of gas generation matter, replacement of gas generation time,and change of gas source kitchen. The gas source kitchen of dispersive liquid hydrocarbon inside of source rocks inherits the characteristics of original gas source kitchen, but the gas source kitchen of dispersive & concentrated liquid hydrocarbon outside of source rocks has occurred the spacial change comparing with original gas source kitchen. The above three liquid hydrocarbon can be cracked into gas at highover mature stage, but the latter is embeded flatter and its time of cracking and gas generation is later than the former, which makes for the late gas accumulations.
This paper creates expulsion oil rate plates of different organic matter abundance through simulation experiments of hydrocarbon generation and expulsion of different organic matter abundance and different lithology source rocks, providing the basis for the reasearch of allocation proportion and quantity of dispersive liquid hydrocarbon inside & outside of source rocks. This paper demonstrates the quantity, distribution and cracking degree of dispersive soluble organic materials of Palaeozoic strata in Tarim basin from the evaluating indicator S1 of hydrocarbon generating potential, heatorigin asphalt and the fluorescence characteristic of reserviors, and makes sure of the reality of successive gas generation of organic matter of Palaeozoic marine source rocks in Tarim basin, and also calculates the cracking gas quantity of dispersive soluble organic matter in middle and lower Cambrian of Tarim basin.The application of successive gas generation mechanism of organic matter can greatly increase the gas exploration potential and hopeness of palaeozoic strata in Tarim basin.
2009, 27(1): 172-179.
Abstract:
The deep natural gas in Guxi fault zone is of the characteristics such as multisource and complex genesis. In view of this problem, based on the analysis of source rocks characteristics, the ternary geochemicaltracing system of natural gas and biomarkers of associated oil were used in order to clarify the geochemical characteristics and genesis of natural gas in the area, combining with analysis on geologic condition of gas pools. It is proposed that the natural gas in Guxi fault zone shows certain regularities and shifts from oiltyped gas to coaltype gas from west to east. Gas in Boshen 6 buried hill is the mixture of highmatured oiltype gas from upper Es4 source rocks in Bonan subsag and oilassociated gas from lower Es3 source rocks. Natural gas from Bogu 4 buried hill mainly consists of highmatured oiltype gas sourced by upper Es4 source rocks, mixed with coaltyped gas. Gas in the second row of Gubei buried hill is the mixture of coaltype and oiltype gas, and natural gas from the third and forth rows is mainly composed of coaltype gas generated by the upper Paleozoic source rocks.
The deep natural gas in Guxi fault zone is of the characteristics such as multisource and complex genesis. In view of this problem, based on the analysis of source rocks characteristics, the ternary geochemicaltracing system of natural gas and biomarkers of associated oil were used in order to clarify the geochemical characteristics and genesis of natural gas in the area, combining with analysis on geologic condition of gas pools. It is proposed that the natural gas in Guxi fault zone shows certain regularities and shifts from oiltyped gas to coaltype gas from west to east. Gas in Boshen 6 buried hill is the mixture of highmatured oiltype gas from upper Es4 source rocks in Bonan subsag and oilassociated gas from lower Es3 source rocks. Natural gas from Bogu 4 buried hill mainly consists of highmatured oiltype gas sourced by upper Es4 source rocks, mixed with coaltyped gas. Gas in the second row of Gubei buried hill is the mixture of coaltype and oiltype gas, and natural gas from the third and forth rows is mainly composed of coaltype gas generated by the upper Paleozoic source rocks.
2009, 27(1): 9-17.
Abstract:
Two phases of bioherms are respectively developed in the middleupper of two descending cycles in the forepart of Changxing Formation in ManyueGanquan section of Kaixian, northeastern Sichuan. By the outcrop surveying, observation by microscope and diffraction of Xray, the composition of bioherms is researched in detail. It is found that the first phase of bioherm in which the biohermbuilding organisms are dominated by cyanobacteria and the lithology includes micrites and dolomitised limestone is composed of biohermbottom and biohermcore. The second phase of bioherm in which the biohermbuilding organisms are dominated by algae primarily and types of sponges and corals later and the lithology includes micrites with partly dolomitation is composed of biohermbottom, biohermcore and biohermtop and turns to reef finally. Based on that, the biohermforming models of two bioherms are discussed: the former which develops on the platform margin shoalslope is low energy bioherm and has two phases of evolvement, while the latter which develops on the platformmargin shoal and reef is high energy bioherm and has four phases of evolvement.
Two phases of bioherms are respectively developed in the middleupper of two descending cycles in the forepart of Changxing Formation in ManyueGanquan section of Kaixian, northeastern Sichuan. By the outcrop surveying, observation by microscope and diffraction of Xray, the composition of bioherms is researched in detail. It is found that the first phase of bioherm in which the biohermbuilding organisms are dominated by cyanobacteria and the lithology includes micrites and dolomitised limestone is composed of biohermbottom and biohermcore. The second phase of bioherm in which the biohermbuilding organisms are dominated by algae primarily and types of sponges and corals later and the lithology includes micrites with partly dolomitation is composed of biohermbottom, biohermcore and biohermtop and turns to reef finally. Based on that, the biohermforming models of two bioherms are discussed: the former which develops on the platform margin shoalslope is low energy bioherm and has two phases of evolvement, while the latter which develops on the platformmargin shoal and reef is high energy bioherm and has four phases of evolvement.
2009, 27(1): 26-31.
Abstract:
In order to study the exploring foreground and hydrocarbon accumulation rules of the Chengbei sag, Bohai Bay Basin, based on the exploring practice of Palaeogene subtle reservoir, the following topics are discussed in this research: the sedimentary evolution history and sedimentary system types of Chengbei Sag; sedimentary facies demarcation and characteristics; reservoir types and accumulation pattern. The conclusions were drawn from the study on the exploring and geological data of Chengbei Sag: The sedimentary evolution history shows that Chengbei Sag experienced four stages: lake basin prerift period, rift spreading period, rift contracting period, and lake basin postrift period; Five types sedimentary facies grows in Palaeogene of Chengbei Sag: nearshore subaqueous fan, beachbars, fandelta, deepwater turbidite fan, and delta; The Palaeogene reservoir can be divided into two accumulation systems: northern abrupt slope and southern gentle slope. The Palaeogene reservoir can be divided into three types: updip pinchout sandstone reservoir, fault block reservoir, and overlap unconformity reservoir. These results show the influence of the sedimentary characteristics to the hydrocarbon accumulation. Hydrocarbon will accumulate easily in the updip pinchout sandstone and overlap unconformity area.
In order to study the exploring foreground and hydrocarbon accumulation rules of the Chengbei sag, Bohai Bay Basin, based on the exploring practice of Palaeogene subtle reservoir, the following topics are discussed in this research: the sedimentary evolution history and sedimentary system types of Chengbei Sag; sedimentary facies demarcation and characteristics; reservoir types and accumulation pattern. The conclusions were drawn from the study on the exploring and geological data of Chengbei Sag: The sedimentary evolution history shows that Chengbei Sag experienced four stages: lake basin prerift period, rift spreading period, rift contracting period, and lake basin postrift period; Five types sedimentary facies grows in Palaeogene of Chengbei Sag: nearshore subaqueous fan, beachbars, fandelta, deepwater turbidite fan, and delta; The Palaeogene reservoir can be divided into two accumulation systems: northern abrupt slope and southern gentle slope. The Palaeogene reservoir can be divided into three types: updip pinchout sandstone reservoir, fault block reservoir, and overlap unconformity reservoir. These results show the influence of the sedimentary characteristics to the hydrocarbon accumulation. Hydrocarbon will accumulate easily in the updip pinchout sandstone and overlap unconformity area.
2009, 27(1): 41-47.
Abstract:
Fisher diagram used to get the Yanchang period accommodation changes, combining the data of outcrop, core and logging in Yanchang group, we identified six period (Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ,Ⅵ) thirddegree flooding layers, and compared them. On this basis, we further studied the lake distribution and overall evolution of the flooding layers, Ⅲ,Ⅳ,Ⅴand Ⅵ, which are corresponding to Chang7, Chang4+5, Chang3 and Chang2
section. Finally through each flooding layer deposition center distribution characteristics, we discussed that the distribution and evolution issues of Yanchang lake basin's sedimentary depression, and believed that the Yanchang lake besides the Chang7 existed a big sedimentary depression, also there were more than one sedimentary depressions in other period, and the sedimentary depressions overall move to the northeast.
Fisher diagram used to get the Yanchang period accommodation changes, combining the data of outcrop, core and logging in Yanchang group, we identified six period (Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ,Ⅵ) thirddegree flooding layers, and compared them. On this basis, we further studied the lake distribution and overall evolution of the flooding layers, Ⅲ,Ⅳ,Ⅴand Ⅵ, which are corresponding to Chang7, Chang4+5, Chang3 and Chang2
section. Finally through each flooding layer deposition center distribution characteristics, we discussed that the distribution and evolution issues of Yanchang lake basin's sedimentary depression, and believed that the Yanchang lake besides the Chang7 existed a big sedimentary depression, also there were more than one sedimentary depressions in other period, and the sedimentary depressions overall move to the northeast.
2009, 27(1): 57-63.
Abstract:
Based on tectonicsequence analysis method and using 3D seismic data, log curves, and cores, Eogene sequence stratigraphy and stratigraphic and lithologic reservoirs prediction are studied in this paper on Liaohe West Depression. One super sequence set, four super sequences and eight sequences are identified in Liaohe West Depression Eogene. Based on syndepositional structural slopebreak types, developed in Liaohe West Depression Eogene, sequences can be divided into syndepositional fault slopebreak sequence, syndepositional bent slopebreak sequence, and gently slope sequence. Syndepositional fault slopebreak sequences develop in super sequence one, two, and three. Syndepositional bent slopebreak sequences and gently slope sequences develop in super sequence four. Sand bodies, in lowstand and highstand systems tract, controlled by syndepositional structural slope break, and hydrocarbon source rocks are collocated very well, which is favorable for hydrocarbon accumulation. Meanwhile, the sand bodies, in secondary porosity zone, have very good porosity and permeability and are favorable for lithologic reservoirs bearing hydrocarbon. Based on the conclusion, the plays of favorable for lithologic reservoirs hydrocarbon bearing are put forward, which are transition zone of hanging wall block of Jin1 fault and Yuanyanggou sag, transition zone of hanging wall block of Shuangtaizi fault and Qinshui sag, and transition zone of hanging wall block of XiaowaHaiwaihe fault and Qinshui sag.
Based on tectonicsequence analysis method and using 3D seismic data, log curves, and cores, Eogene sequence stratigraphy and stratigraphic and lithologic reservoirs prediction are studied in this paper on Liaohe West Depression. One super sequence set, four super sequences and eight sequences are identified in Liaohe West Depression Eogene. Based on syndepositional structural slopebreak types, developed in Liaohe West Depression Eogene, sequences can be divided into syndepositional fault slopebreak sequence, syndepositional bent slopebreak sequence, and gently slope sequence. Syndepositional fault slopebreak sequences develop in super sequence one, two, and three. Syndepositional bent slopebreak sequences and gently slope sequences develop in super sequence four. Sand bodies, in lowstand and highstand systems tract, controlled by syndepositional structural slope break, and hydrocarbon source rocks are collocated very well, which is favorable for hydrocarbon accumulation. Meanwhile, the sand bodies, in secondary porosity zone, have very good porosity and permeability and are favorable for lithologic reservoirs bearing hydrocarbon. Based on the conclusion, the plays of favorable for lithologic reservoirs hydrocarbon bearing are put forward, which are transition zone of hanging wall block of Jin1 fault and Yuanyanggou sag, transition zone of hanging wall block of Shuangtaizi fault and Qinshui sag, and transition zone of hanging wall block of XiaowaHaiwaihe fault and Qinshui sag.
2009, 27(1): 70-76.
Abstract:
The analysis of the distribution trait of the coal seam, sedimentary facies and paleogeography, environment types of coal accumulating and the temporal and spatial distribution in the Early Permian of Ordos Basin shows that the main coal accumulating sedimentary systems are beachbarrier, tidal delta and fluvial or delta plain, and the continental mire marshes and the marine peat flat are the main coalbearing environment. The three main coalbearing systems are the beachbarrier coal accumulating system, the tidal delta coalbearing system and the fluvial or delta plain coalbearing system, which formed the main economic coalbed. The controlling factor of the formation and protection to the coalbed is the accommodation space variation rate which is relevant to the peat sediment.
The analysis of the distribution trait of the coal seam, sedimentary facies and paleogeography, environment types of coal accumulating and the temporal and spatial distribution in the Early Permian of Ordos Basin shows that the main coal accumulating sedimentary systems are beachbarrier, tidal delta and fluvial or delta plain, and the continental mire marshes and the marine peat flat are the main coalbearing environment. The three main coalbearing systems are the beachbarrier coal accumulating system, the tidal delta coalbearing system and the fluvial or delta plain coalbearing system, which formed the main economic coalbed. The controlling factor of the formation and protection to the coalbed is the accommodation space variation rate which is relevant to the peat sediment.
2009, 27(1): 87-93.
Abstract:
Matrixsupported carbonatite boulders and pebbles were discretely cropped out to the northeast of Liujing town, where they unconformably overlie the Lower Devonian Moding and Najiao Formations, in which dual textures are well exhibited. Few attentions have been paid to the alluvial fan deposits ever since they were noticed. After careful examination on the coarse deposits, in comparison with the modern and ancient alluvial fan analogues, these discrete red coarse deposits are proposed as the remains of different parts of one Paleogene piedmont alluvial fan, sourced by the carbonate hinterland under a dry climate.
Matrixsupported carbonatite boulders and pebbles were discretely cropped out to the northeast of Liujing town, where they unconformably overlie the Lower Devonian Moding and Najiao Formations, in which dual textures are well exhibited. Few attentions have been paid to the alluvial fan deposits ever since they were noticed. After careful examination on the coarse deposits, in comparison with the modern and ancient alluvial fan analogues, these discrete red coarse deposits are proposed as the remains of different parts of one Paleogene piedmont alluvial fan, sourced by the carbonate hinterland under a dry climate.
2009, 27(1): 111-117.
Abstract:
Based on the synthetic analysis of the mass susceptibility and grain size from the YZ core obtained from Subei basin, the process and characters of palaeoclimate evolution during the past
16.7 ka were revealed. The results show that during the past 16.7 cal kaBP, the palaeoclimate of Subei basin has experienced several phases: 16.7~13.5 cal kaBP, relatively humid period; 13.5~11.2 cal kaBP, extremely arid period; 11.2~1.1 cal kaBP, relatively steady humidity period. In addition, the indexes also recorded several climate events. YD event and 3.0cal kaBP events are obviously. The aridhumid fluctuations since around 16.7 ka disclosed by YZ core reveals a strong correlation with the GRIP oxygen isotope record and Donggedong’s stalagmite oxygen isotope record. This indicates that the climate changes in the study area not only has great regional character, but also has great correlation with the global climate changes.
Based on the synthetic analysis of the mass susceptibility and grain size from the YZ core obtained from Subei basin, the process and characters of palaeoclimate evolution during the past
16.7 ka were revealed. The results show that during the past 16.7 cal kaBP, the palaeoclimate of Subei basin has experienced several phases: 16.7~13.5 cal kaBP, relatively humid period; 13.5~11.2 cal kaBP, extremely arid period; 11.2~1.1 cal kaBP, relatively steady humidity period. In addition, the indexes also recorded several climate events. YD event and 3.0cal kaBP events are obviously. The aridhumid fluctuations since around 16.7 ka disclosed by YZ core reveals a strong correlation with the GRIP oxygen isotope record and Donggedong’s stalagmite oxygen isotope record. This indicates that the climate changes in the study area not only has great regional character, but also has great correlation with the global climate changes.
2009, 27(1): 128-136.
Abstract:
Through equidistantly sampling on 2～3 meters and accurate systematic measurement of samples of Xichagou stratotype section, located in southwesern limb of Ganchaigou anticline in western Qaidam Basin(Chaixi area) ,integrated high resolution and high precision magnetostratigraphy and sedimentological study in this section, authors think the changing trends of magnetic fabric parameters of sedimentary rocks may act as proxies of climate change.It was indicated that environmental change between 22.4 to 6.2 Ma may divide into three stages: first stage: humid context between ~22.4 to 13.4 Ma; secondary stage: warmarid environment transformed aridcold one from 13.4 to 8.2 Ma, and third stage from 8.2 to 6.2 Ma, climate lasted drycold, and more complexly. It can be considered that rhythm of climate change or tectonism correlated to formation of modern monsoon since 7.8 Ma. This result provides available evidence for the uplift process of Tibetan Plateau and its environmental effectes.
Through equidistantly sampling on 2～3 meters and accurate systematic measurement of samples of Xichagou stratotype section, located in southwesern limb of Ganchaigou anticline in western Qaidam Basin(Chaixi area) ,integrated high resolution and high precision magnetostratigraphy and sedimentological study in this section, authors think the changing trends of magnetic fabric parameters of sedimentary rocks may act as proxies of climate change.It was indicated that environmental change between 22.4 to 6.2 Ma may divide into three stages: first stage: humid context between ~22.4 to 13.4 Ma; secondary stage: warmarid environment transformed aridcold one from 13.4 to 8.2 Ma, and third stage from 8.2 to 6.2 Ma, climate lasted drycold, and more complexly. It can be considered that rhythm of climate change or tectonism correlated to formation of modern monsoon since 7.8 Ma. This result provides available evidence for the uplift process of Tibetan Plateau and its environmental effectes.
2009, 27(1): 142-146.
Abstract:
The distribution of the nalkanes in the Hongyuan peat core of the northeastern Qinghaixizang Plateau was systematically analyzed based on the GCMS analysis. The organism records during the Holocene were reconstructed in this region. The regular variation between the dominant C25 and C31 nalkanes concentration in the peat core reveal that the peat swamp possibly occur the replacement of the morphologically based species or the chemicallybased species during the Holocene. This replacement might be the result of climatic change. When the climate fluctuates largely, the swamp possibly appears the replacement between aquatic plants and the terrestrial plants; On the contrary, when the climate has a small variation, the chemicallybased species will present replacement. The results are compared with pollen records in the same region. The discrepancy between the nalkanes and pollen records was analyzed. One of reason is the nalkanes mainly record the composition of plant debris deposited locally, the pollen assemblage is more an average signal of the flora over a wider area. The results give a new proof for the biology information of the Holocene in the QinghaiXizang Plateau. The author also proposes lipid biomarkers (such as nalkanes) can be viewed as the effective tool of vegetation reconstruction, together with the pollen, and will gain the detailed vegetation evolution history.
The distribution of the nalkanes in the Hongyuan peat core of the northeastern Qinghaixizang Plateau was systematically analyzed based on the GCMS analysis. The organism records during the Holocene were reconstructed in this region. The regular variation between the dominant C25 and C31 nalkanes concentration in the peat core reveal that the peat swamp possibly occur the replacement of the morphologically based species or the chemicallybased species during the Holocene. This replacement might be the result of climatic change. When the climate fluctuates largely, the swamp possibly appears the replacement between aquatic plants and the terrestrial plants; On the contrary, when the climate has a small variation, the chemicallybased species will present replacement. The results are compared with pollen records in the same region. The discrepancy between the nalkanes and pollen records was analyzed. One of reason is the nalkanes mainly record the composition of plant debris deposited locally, the pollen assemblage is more an average signal of the flora over a wider area. The results give a new proof for the biology information of the Holocene in the QinghaiXizang Plateau. The author also proposes lipid biomarkers (such as nalkanes) can be viewed as the effective tool of vegetation reconstruction, together with the pollen, and will gain the detailed vegetation evolution history.
2009, 27(1): 164-171.
Abstract:
Tahe oilfield of Tarim basin is the largest oilfield found in Paleozoic marine carbonate in China so far. However, its oil source is not still ascertained. In this paper, geochemical compositions of the crude oils of Tahe oilfield and CambrianOrdovician source rocks were studied, and oil source correlation was carried out. The compositional and distributional characteristics of nalkanes, isoprenoid hydrocarbons, steranes and terpanes in crude oils and source rocks indicate that the studied crude oils are closely related to CambrianOrdovician source rocks. This is identical with the geological fact that Tahe oilfield has undergone the longterm and multiperiod accumulation process which permitted the CambrianOrdovician source rocks to continuouslly supply crude oil for the oilfield. This result still shows that the difference in biomarker compositions between the crude oils from Tahe oilfield and CambrianOrdovician source rocks may be related to the contribution of these biomarker compounds originated from different evolutionary stages of organic matter. This should be paid special attention to study the correlation of oil and source rock with high maturity.
Tahe oilfield of Tarim basin is the largest oilfield found in Paleozoic marine carbonate in China so far. However, its oil source is not still ascertained. In this paper, geochemical compositions of the crude oils of Tahe oilfield and CambrianOrdovician source rocks were studied, and oil source correlation was carried out. The compositional and distributional characteristics of nalkanes, isoprenoid hydrocarbons, steranes and terpanes in crude oils and source rocks indicate that the studied crude oils are closely related to CambrianOrdovician source rocks. This is identical with the geological fact that Tahe oilfield has undergone the longterm and multiperiod accumulation process which permitted the CambrianOrdovician source rocks to continuouslly supply crude oil for the oilfield. This result still shows that the difference in biomarker compositions between the crude oils from Tahe oilfield and CambrianOrdovician source rocks may be related to the contribution of these biomarker compounds originated from different evolutionary stages of organic matter. This should be paid special attention to study the correlation of oil and source rock with high maturity.
2009, 27(1): 180-185.
Abstract:
Sterane series compounds such as C21，C22 and C27~C29 can be usually detected in sediments, however, C19,C20,C23~C26 steranes rarely occur in above geologic body. The C19~C29 sterane series and C26~C29 25norhopanes are detected of high abundance in blackshale sample from Lucaogou Fomation, Santanghu Basin. Such abundant compounds contain much information in oilgas geochemistry research, but until now, few research works have been carried out in the world. Based on our detail studies, a conclusion has been reached that the two series compounds can indicate arid and salinelake environment, and the low hydrobiont of algae and plankton are well developed. The organic matters in sediments suffer severe biodegradation, and then the products of biodegradation and the original organic matter are preserved well and become into the precursor of hydrocarbons.
Sterane series compounds such as C21，C22 and C27~C29 can be usually detected in sediments, however, C19,C20,C23~C26 steranes rarely occur in above geologic body. The C19~C29 sterane series and C26~C29 25norhopanes are detected of high abundance in blackshale sample from Lucaogou Fomation, Santanghu Basin. Such abundant compounds contain much information in oilgas geochemistry research, but until now, few research works have been carried out in the world. Based on our detail studies, a conclusion has been reached that the two series compounds can indicate arid and salinelake environment, and the low hydrobiont of algae and plankton are well developed. The organic matters in sediments suffer severe biodegradation, and then the products of biodegradation and the original organic matter are preserved well and become into the precursor of hydrocarbons.
