Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the we...Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the well logging data,core samples,outcrops,and geochemistry of black shales in the Lianggaoshan Formation in the Sichuan Basin.Our analysis focused on the lake basin evolution and the migration characteristics,paleoenvironmental features,formation mechanisms,and developmental model of the black shales.The results indicated that black shales in the Lianggaoshan Formation exhibited significant lateral migration,with an overall thickening trend from east to west.Within the 1st Member of the formation,black shale occurred as a single thick layer in the eastern region that gradually thinned toward the central region.Multiple sets of shale developed within the 2nd and 3rd members,and these had lower thicknesses than the 1st Member and migrated toward central Sichuan.Paleoproductivity and terrigenous input were the main factors controlling the deposition of black shales.A semi-humid climate influenced the deposition of black shales,bringing abundant freshwater,terrigenous debris,and nutrients into the basin.Decomposition of organic matter consumed oxygen in sediment and bottom water,causing localized oxygen deficiency in the strata.展开更多
Based on the field outcrops surveyed,combined with recent published the regional tectonic evolution and geochronology data,we analyzed the lithologies and rock associations of strata,identified the sedimentary facies ...Based on the field outcrops surveyed,combined with recent published the regional tectonic evolution and geochronology data,we analyzed the lithologies and rock associations of strata,identified the sedimentary facies types,and discussed the distribution sedimentary facies and the hydrocarbon accumulation in the eastern Qiangtang basin during the Late Triassic–Jurassic.Marked by regional unconformities,there are two tectono-stratigraphic units(from the Carnian to the Norian and from the Rhaetian to the Kimmeridgian,respectively)in the eastern part of Qiangtang basin.We systematically described the distribution range,thickness variation and lithological characteristics of different formations in the tectonostratigraphic units.The Late Triassic-Jurassic is dominated by marine facies and marine-continental transitional facies.The marine-continental transitional facies include deltaic and tidallagoon facies.Marine facies including gentle carbonate slope,evaporative platform,restricted platform,littoral,neritic,bathyal and abysmal facies.The Carnian stage is dominated by littoral–neritic–bathyal–abysmal facies in the north Qiangtang depression otherwise the littoral–neritic facies in the south Qiangtang depression.The early Norian stage is dominated by carbonate gentle slope-mixed continental shelf facies.The late Norian,Bajocian,Callovian and Kimmeridgian stage are dominated by tidal flat-delta facies in the north Qiangtang depression and littoral-neritic facies in the south Qiangtang depression.The Bathonian and Oxfordian stage are dominated by evaporative platform-restricted platform-mixed continental shelf facies.The sedimentary facies formed zones from north to south and extended in an E–W direction.The Eastern Lower Uplift(ELU)played an important role in the division zones of sedimentary facies from north to south.During the Bathonian and Oxfordian,the ELU developed below the sea level and controlled the distribution of restricted platform,evaporative platform and platform margin.We analyzed 20 source rock samples from the upper Triassic-Jurassic.The total organic carbon(TOC)value from Qoimaco,Buqu and Adula Formations.of late TriassicJurassic in the eastern Qiangtang basin are ranges from 0.17~0.33%(average 0.28%),0.05~0.25%(average 0.15%)and 10.32~28.78%(average 19.33%),respectively.Obviously,the Adula Fm.developed good source rocks.The values of Tmax and S1+S2 in the Adula formation are 459-461℃(average 460℃)and 6.75-28.55 mg/g(average 18.18 mg/g),indicating that the Adula source rock has reached high-over-maturity stage.The bathyal,gentle slop and platform facie belts of the Upper Triassic can configurate the good hydrocarbon prospects in the northeastern area of the Qiangtang basin.展开更多
Based on a large number of geological and geophysical data,the formation,fracture-caves types and hydrocarbon distribution of hoodoo-upland on the Ordovician karst slope in the Tahe area,Tarim Basin,are discussed by a...Based on a large number of geological and geophysical data,the formation,fracture-caves types and hydrocarbon distribution of hoodoo-upland on the Ordovician karst slope in the Tahe area,Tarim Basin,are discussed by analyzing faults and strata thickness.The hoodoo-upland was made of high peaks and narrow valleys in the Ordovician karst slope during the Early Hercynian karst period,which were distributed along the NNE positive flower structure and had inherited evolution.The fault-fractures and fracture-vugs complex were extremely developed,with a thickness of 100 m.The cumulative oil production of 60% oil wells was more than 20×10^(4) t per well in the hoodoo-upland,where the residual thickness of the Ordovician Yingshan Formation was greater than karst depressions.Caves formed by the shelter of collapsed breccias were developed in the valleys.They were 1.6 to 13.5 m high,with a filling rate of 51.6%.The positive flower structure under the settings of strike-slip compression controlled the early formation of the hoodoo-upland on the karst slope,resulting in the differences of drainage distribution and karstification.Compared with the water-rich karst valley,the hoodoo-upland with lean water suffered weaker karstification,had thicker residual stratum,and was higher in terrain.In rainy season,the meteoric water flew and corrode along the cracks,forming a complex network of fractures and caves.Combined with inherited uplift and the effective match of the NNE deep faults,oil and gas continuously charged into the reservoir space in the upland,forming the hoodoo fracture-cave reservoir with vertically quasi continuous distribution,high hydrocarbon abundance and high production.展开更多
Since the1990s,China has become a net importer of petroleum(including crude and refined oil).The new century has seen the country more dependent upon imported oil at a higher price.This has drew attention both from ab...Since the1990s,China has become a net importer of petroleum(including crude and refined oil).The new century has seen the country more dependent upon imported oil at a higher price.This has drew attention both from abroad and domestic.This article tries to analyze the factors that affect the volume of import,the influence of import upon the economy development and energy security and deal with issues展开更多
(from No.4, 2012 )Countermeasures for more oil and gas imports China’s imports of oil and gas may both take the lead in the world A rapid increase of petroleum consumption in China is almost inevitable and any attemp...(from No.4, 2012 )Countermeasures for more oil and gas imports China’s imports of oil and gas may both take the lead in the world A rapid increase of petroleum consumption in China is almost inevitable and any attempt to slow the pace would sure face difficulties. According to BP’s Statistical Review of World Energy, the crude展开更多
Economy growth in China is expected to slow down a little during the I3th Five-Year-Plan period. So will the domestic gas demand and supply market, which may be quite different from that of the 11 th and 12th Five-Yea...Economy growth in China is expected to slow down a little during the I3th Five-Year-Plan period. So will the domestic gas demand and supply market, which may be quite different from that of the 11 th and 12th Five-Year-Plan periods. The paper summarized the state quo of gas supply and demand in the country and analyzed factors that may affect the demand and supply balance in the new period. It is proposed that there will be many uncertainties in achieving supply and demand goals of gas set for tire period, and gas glut is also very possible during the time. To deal with the problem, it is suggested that several measures be taken nationwide： improving utilization of gas in several sectors, straightening and optimizing the pricing mechanism, speeding up construction of infrastructures, implementing relevant policies and boosting up supen^ision and monitor of tire industry.展开更多
In-situ stress is a critical factor influencing the permeability of coal reservoirs and the production capacity of coalbed methane(CBM)wells.Accurate prediction of in-situ stress and investigation of its influence on ...In-situ stress is a critical factor influencing the permeability of coal reservoirs and the production capacity of coalbed methane(CBM)wells.Accurate prediction of in-situ stress and investigation of its influence on coal reservoir permeability and production capacity are significant for CBM development.This study investigated the CBM development zone in the Zhengzhuang area of the Qinshui Basin.According to the low mechanical strength of coal reservoirs,this study derived a calculation model of the in-situ stress of coal reservoirs based on the multi-loop hydraulic fracturing method and analyzed the impacts of initial fractures on the calculated results.Moreover,by combining the data such as the in-situ stress,permeability,and drainage and recovery data of CBM wells,this study revealed the spatial distribution patterns of the current in-situ stress of the coal reservoirs and discussed the impacts of the insitu stress on the permeability and production capacity.The results are as follows.(1)Under given fracturing pressure,longer initial fractures are associated with higher calculated maximum horizontal principal stress values.Therefore,ignoring the effects of the initial fractures will cause the calculated values of the in-situ stress to be less than the actual values.(2)As the burial depth increases,the fracturing pressure,closure pressure,and the maximum and minimum horizontal principal stress of the coal reservoirs in the Zhengzhuang area constantly increase.The average gradients of the maximum and minimum horizontal principal stress are 3.17 MPa/100 m and 2.05 MPa/100 m,respectively.(3)Coal reservoir permeability is significantly controlled by the magnitude and state of the current in-situ stress.The coal reservoir permeability decreases exponentially with an increase in the effective principal stress.Moreover,a low lateral pressure coefficient(less than 1)is associated with minor horizontal compressive effects and high coal reservoir permeability.(4)Under similar conditions,such as resource endowments,CBM well capacity is higher in primary structural coal regions with moderate paleotectonic stress modification,low current in-situ stress,and lateral pressure coefficient of less than 1.展开更多
China is abundant in unconventional gas, and stunning growth of gas reserves and production therefore can be expected in foreseeable future because of the exploration and development of the gas. For the next 5 to 10 y...China is abundant in unconventional gas, and stunning growth of gas reserves and production therefore can be expected in foreseeable future because of the exploration and development of the gas. For the next 5 to 10 years, conventional gas will still dominate energy market but in a long run, its influence will weaken gradually as unconventional gas kicks in and expands. Though the exploration and development of unconventional gas in China is still at a very early stage, three Chinese oil majors have already assessed the resources, including tight gas, coal-bed methane, shale gas and gas hydrate.展开更多
The ocean crust remnants of the Proto-Tethys were preserved as the Kudi ophiolites in the West Kunlun Orogenic Belt(WKOB),and its evolutionary history was mainly constructed by research on igneous or metamorphic rocks...The ocean crust remnants of the Proto-Tethys were preserved as the Kudi ophiolites in the West Kunlun Orogenic Belt(WKOB),and its evolutionary history was mainly constructed by research on igneous or metamorphic rocks in the WKOB.Sedimentary rocks in the WKOB received little attention in the past;however,they could provide important constraints on the evolution of the oceanic lithosphere.Here,a series of shales and greywackes found in the Kudi area of WKOB were studied to constrain their deposition ages and explore their significance in the evolution of the ProtoTethys oceanic crust.The U-Pb dating and europium anomaly(Eu/Eu^(*))were analyzed for detrital zircons from greywackes interlayers,while bulk rare earth elements and yttrium(REY)of the shales were measured.Detrital zircons U-Pb ages yield a maximum deposition age of 436 Ma for the greywackes and black shales,while the REY distribution patterns of the black shales are similar to those of the Tarim Ordovician Saergan shales.Accordingly,the studied WKOB black shales were deposited in the Proto-Tethys Ocean during the Late Ordovician-Early Silurian period.The maximum deposition age at 436 Ma may represent a minimum closure time of the Proto-Tethys Ocean,which is also supported by the absence of increases in Eu/Eu^(*)values during the Late Ordovician-Early Silurian.Besides,our Eu/Eu^(*)values in detrital zircons indicate diminished orogenesis during the Archean to Meso-Proterozoic,subduction-related accretion at the margins of the supercontinent Rodinia during the Neoproterozoic.展开更多
During the CO_(2)injection and geological storage process,the integrity of the cap rock significantly influences the long-term safety of CO_(2)storage.Natural fractures within the cap rock serve as potential pathways ...During the CO_(2)injection and geological storage process,the integrity of the cap rock significantly influences the long-term safety of CO_(2)storage.Natural fractures within the cap rock serve as potential pathways for CO_(2)migration,thereby increasing the risk of CO_(2)leakage.In this study,we determined the types,developmental characteristics,permeability changes,and CO_(2)-H_(2)O-Rock reactions of natural fractures in the mudstone cap rocks of the Sanduo Formation(E_(3)s)and Dainan Formation(E_(2)d)in the Gaoyou Sag of the Subei Basin using core observations,thin-section analysis,rock mechanics experiments,and paleomagnetic directional analysis.We identified four tectonic fracture sets(NNW,NWW,EW,and NE);high-angle shear fractures,ranging from 60°to 90°(average 82°)and typically measuring4-12 cm(average 7.5 cm),dominate the assemblage,while slip fractures,ranging from 32°to 50°(average 36°)and measuring 3-6 cm(average 3.9 cm),are also present.At the microscale,shear fractures average 160μm,and bedding fractures average 82μm.Notably,85.78%of shear fractures are unfilled,with calcite filling observed in 14.22%,while other fracture types show no filling.Permeability tests on samples without fractures reveal that permeability declines rapidly below 9 MPa,especially in shallower samples,followed by a slower reduction between 9 and 13 MPa,and ultimately stabilizes at approximately 0.00003 mD.In contrast,samples with fractures exhibit permeability that is 3-4 orders of magnitude higher;their fracture permeability decays according to a power law with pressure yet remains above 10 mD even at 46 MPa.Fractures with larger dip angles and those aligned with the maximum principal stress demonstrate the highest permeability.While silicate-filled fractures exhibit negligible changes in permeability,carbonate-filled fractu res experience a temporary enhancement due to dissolution;however,subsequent permeability remains controlled by factors such as effective stress and fracture orientation.展开更多
The tectonic event during Cretaceous and its relationship with hydrocarbon accumulation in the Qiangtang Basin is discussed based on zircon U-Pb dating and the study of deformation, thermochronology and hydrocarbon fo...The tectonic event during Cretaceous and its relationship with hydrocarbon accumulation in the Qiangtang Basin is discussed based on zircon U-Pb dating and the study of deformation, thermochronology and hydrocarbon formation. LA-ICPMS zircon U-Pb dating indicates that the tectonic event took place during the Early-Late Cretaceous （125-75Ma）. The event not only established the framework and the styles of structural traps in the basin, but also led to the cessation of the first hydrocarbon formation and the destruction of previous oil pools. The light crude oil in the basin was formed during the second hydrocarbon formation stage in the Cenozoic, and ancient structural traps formed during the Cretaceous event are promising targets for oil and gas exploration.展开更多
Great volumes of shallow-buried （〈2,000 m） natural gases which are mainly composed of biogases and low-mature gases have been found in the Mesozoic-Cenozoic sedimentary basins in China. Many shallow gas reservoirs ...Great volumes of shallow-buried （〈2,000 m） natural gases which are mainly composed of biogases and low-mature gases have been found in the Mesozoic-Cenozoic sedimentary basins in China. Many shallow gas reservoirs in China are characterized by coexistence of biogas and low-mature gas, so identifying the genetic types of shallow gases is important for exploration and development in sedimentary basins. In this paper, we study the gas geochemistry characteristics and distribution in different basins, and classify the shallow gas into two genetic types, biogas and low-mature gas. The biogases are subdivided further into two subtypes by their sources, the source rock-derived biogas and hydrocarbon-derived biogas. Based on the burial history of the source rocks, the source rock-derived biogases are divided into primary and secondary biogas. The former is generated from the source rocks in the primary burial stage, and the latter is from uplifted source rocks or those in a secondary burial stage. In addition, the identifying parameters of each type of shallow gas are given. Based on the analysis above, the distributions of each type of shallow gas are studied. The primary biogases generated from source rocks are mostly distributed in Quaternary basins or modem deltas. Most of them migrate in watersoluble or diffused mode, and their migration distance is short. Reservoir and caprock assemblages play an important role in primary biogas accumulation. The secondary biogases are distributed in a basin with secondary burial history. The oil-degraded biogases are distributed near heavy oil pools. The low-mature gases are widely distributed in shallow-buried reservoirs in the Meso-Cenozoic basins.展开更多
By using the latest geological,seismic,drilling and logging data,this article studies the basic conditions for the formation of the total petroleum system and the orderly coexisting characteristics and accumulation mo...By using the latest geological,seismic,drilling and logging data,this article studies the basic conditions for the formation of the total petroleum system and the orderly coexisting characteristics and accumulation models of conventional&unconventional reservoirs in the Lower Permian Fengcheng Formation in the Junggar Basin.Controlled by thermal evolution,hydrocarbon generation and expulsion process of the high-quality source rocks in alkaline lake as well as the characteristics of multi-type reservoirs(conglomerate,sandstone,dolomite and shale),conventional structure-lithologic reservoirs and tight oil and shale oil reservoirs controlled by source-reservoir structure have been formed.On the plane,mature conventional reservoirs,medium-high mature tight oil,and medium-high mature shale oil reservoirs coexist orderly from the slope area around Mahu sag to the sag.Based on the orderly coexisting characteristics of conventional and unconventional reservoirs in the Fengcheng Formation,it is clear that oil and gas in the Fengcheng Formation accumulate continuously over a large area in three accumulation models:integrated source-reservoir,source-reservoir in close contact,and separated source-reservoir model.The three accumulation models differ in relationship between source-reservoir structure,reservoir lithology and spatial distribution,hydrocarbon migration,oil and gas type.It is pointed out that the conventional&unconventional oil and gas should be explored and developed as a whole to achieve an overall breakthrough of the total petroleum system.This study is expected to enrich the geological theory of oil and gas enrichment in continental basins and to provide an analogy for exploration and research in other hydrocarbon-rich sags.展开更多
The study area is located in the south of Huanxian county,in Yan'an and Puxian counties and to the north of Xi'an.The Shanxi and lower Shihezi formations are important gas-bearing formations.Given our analysis...The study area is located in the south of Huanxian county,in Yan'an and Puxian counties and to the north of Xi'an.The Shanxi and lower Shihezi formations are important gas-bearing formations.Given our analysis of the direction of rivers,the contents of stable heavy minerals and of feldspar of palaeo river systems,the study area is divided into six palaeodrainage patterns corresponding to six feldspar regions and six sedimentary facies regions.On this basis,the distribution of sedimentary facies was also analyzed.During the Shanxi stage,a delta front was deposited in the Huanxian region and delta plains and fronts were deposited in the Pingliang,Chunhua-Yaoxian and Hancheng-Chengcheng regions.In the Yan'an-Daning region,only a delta front was developed.The distribution of sedimentary facies in the earlier Shihezi stage originated from the Shanxi stage.A delta front was developed in the Huanxian region while a delta plain and front developed in the Pingliang-Zhenyuan region during the same time.Lakes originated only in the Zhenyuan-Huanxian-Huachi-Zhengning and Daning-Jixian zones.This analytical method shows that different palaeodrainage patterns can be effectively distinguished in order to forecast sedimentary facies.展开更多
Rare earth element compositions of Lower Ordovician dolomites in the Central and Northern Tarim Basin are studied. Most dolomite samples are more or less contaminated by clay minerals. Their rare earth element composi...Rare earth element compositions of Lower Ordovician dolomites in the Central and Northern Tarim Basin are studied. Most dolomite samples are more or less contaminated by clay minerals. Their rare earth element compositions have been consequently changed, showing both seawater-like and non-seawater-like features. The clay contamination should be disposed before the REE data are used. Through ICP-MS and ICP-AES analyses, the REE features are well documented. The clay contamination is quantitatively determined by microscopic investigation, trace elements and REE contents. The dolomites, at least in the Tarim Basin, are thought to be pure when their total LREE contents are less than 3×10^-6. Through comparison, the pure dolomites show similarities in REE patterns but differences in REE contents with co-existing pure limestone, which indicates that dolomitization may slightly change the REE compositions. Nevertheless, whatever the change is, the pure dolomites may act as a potential REE proxy for Ordovician seawater, which would be significant for ancient massive dolomite strata that lack limestone.展开更多
The Central Gas Field is a famous large-sized gas field in the Ordos Basin of China. However, identification of main gas sources of the Ordovician reservoirs in this gas field remains puzzling. On the basis of a lot o...The Central Gas Field is a famous large-sized gas field in the Ordos Basin of China. However, identification of main gas sources of the Ordovician reservoirs in this gas field remains puzzling. On the basis of a lot of geochemical data and geological research on natural gases, the characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin were studied. The results indicated that natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin have similar chemical and isotopic compositions to highly mature and over-mature dry gases. Both coal-derived gases and oil-type gases coexist in the Central Gas Field in the Ordos Basin. The former was derived mainly from Carboniferous-Permian coal measures and the latter from Lower Paleozoic marine carbonates. It is suggested that coal-derived gases occur in the eastern part of the Central Gas Field while oil-type gases may be produced mainly in the northern, western and southern parts of the Central Gas Field in the Ordos Basin.展开更多
The formation and evolution of basins in the China continent are closely related to the collages of many blocks and orogenic belts. Based on a large amount of the geological, geophysical, petroleum exploration data an...The formation and evolution of basins in the China continent are closely related to the collages of many blocks and orogenic belts. Based on a large amount of the geological, geophysical, petroleum exploration data and a large number of published research results, the basement constitutions and evolutions of tectonic-sedimentary of sedimentary basins, the main border fault belts and the orogenesis of their peripheries of the basins are analyzed. Especially, the main typical basins in the eight divisions in the continent of China are analyzed in detail, including the Tarim, Ordos, Sichuan, Songliao, Bohai Bay, Junggar, Qiadam and Qiangtang basins. The main five stages of superimposed evolutions processes of basins revealed, which accompanied with the tectonic processes of the Paleo-Asian Ocean, Tethyan and Western Pacific domains. They contained the formations of main Cratons （1850-800 Ma）, developments of marine basins （800-386 Ma）, developments of Marine- continental transition basins and super mantle plumes （386-252 Ma）, amalgamation of China Continent and developments of continental basins （252-205 Ma） and development of the foreland basins in the western and extensional faulted basin in the eastern of China （205~0 Ma）. Therefore, large scale marine sedimentary basins existed in the relatively stable continental blocks of the Proterozoic, developed during the Neoproterozoic to Paleozoic, with the property of the intracontinental cratons and peripheral foreland basins, the multistage superimposing and late reformations of basins. The continental basins developed on the weak or preexisting divisional basements, or the remnant and reformed marine basins in the Meso-Cenozoic, are mainly the continental margins, back-arc basins, retroarc foreland basins, intracontinental rifts and pull-apart basins. The styles and intensity deformation containing the faults, folds and the structural architecture of regional unconformities of the basins, responded to the openings, subductions, closures of oceans, the continent-continent collisions and reactivation of orogenies near the basins in different periods. The evolutions of the Tianshan-Mongol-Hinggan, Kunlun-Qilian-Qinling-Dabie-Sulu, Jiangshao-Shiwandashan, Helanshan-Longmengshan, Taihang-Wuling orogenic belts, the Tibet Plateau and the Altun and Tan- Lu Fault belts have importantly influenced on the tectonic-sedimentary developments, mineralization and hydrocarbon reservoir conditions of their adjacent basins in different times. The evolutions of basins also rely on the deep structures of lithosphere and the rheological properties of the mantle. The mosaic and mirroring geological structures of the deep lithosphere reflect the pre-existed divisions and hot mantle upwelling, constrain to the origins and transforms dynamics of the basins. The leading edges of the basin tectonic dynamics will focus on the basin and mountain coupling, reconstruction of the paleotectonic-paleogeography, establishing relationship between the structural deformations of shallow surface to the deep lithosphere or asthenosphere, as well as the restoring proto-basin and depicting residual basin of the Paleozoic basin, the effects of multiple stages of volcanism and paleo- earthquake events in China.展开更多
The Triassic Lower Karamay Formation（T2k1） is one of the main oil-bearing stratigraphic units in the northwestern margin of Junggar Basin（NW Junggar）, China. Based on an integrated investigation of outcrops, well ...The Triassic Lower Karamay Formation（T2k1） is one of the main oil-bearing stratigraphic units in the northwestern margin of Junggar Basin（NW Junggar）, China. Based on an integrated investigation of outcrops, well logs and seismic data of NW Junggar, the Lower Karamay Formation is subdivided into 2 sets, 6 beds and 13 layers. Also, it is considered that the alluvial fan, the braided river, the meandering river and the shore-shallow lacustrine were developed during the early period of Middle Triassic in Karamay districts Ⅰ, Ⅲ. The Lower Karamay Formation deposits the following 9 sedimentary subfacies： the lower fan, the middle fan, the upper fan, the braided channel, the overflow bank, the river flood of braided river, the meandering channel, the river flood of meandering river, the shore-shallow lacustrine. Seventeen microfacies such as the braided stream channel, the alluvial sand floodplain, the alluvial glutenite floodplain, the water channel, the channel bar etc. have been identified in subfacies as well. The thickness of strata is firstly up-thinning and then thickening upward to the top, it is a process from large-scale lacustrine transgression to partly lacustrine regression. Furthermore, the microfacies planar distributing law proves that the remaining oil may enrich along the margin of microfacies because of the planar microfacies changes. Therefore, this research is beneficial for searching remaining oil in NW Junggar and providing information to the project ＂The Secondary Exploration＂ of PetroChina.展开更多
To unveil formation mechanism of key sequence boundaries of inland faulting basin and coal accumulation charac- teristics of coal seams in isochrohal stratigraphic framework, sequence stratigraphy, palaeogeographic re...To unveil formation mechanism of key sequence boundaries of inland faulting basin and coal accumulation charac- teristics of coal seams in isochrohal stratigraphic framework, sequence stratigraphy, palaeogeographic recovery and other methods were used to research the sequence stratigraphy and coal accumulation in the example of Banding Basn in the west margin of Yangtze Platform, and the authors advanced a coal accumulation model of Faulting basin on the basis of accommo- dation space changes in the background of palaeogeography of sequence framework. The results show that： normal lacustrine regression and forced lacustrine regression are the main driving forces for the formation of sequence boundaries of Faulting ba- sin; basement subsidence is the main source of accommodation space of Faulting basin; and subsidence disequilibrium is the main cause for the difference in generation rate of accommodation space of Faulting basin. Coal accumulation in Faulting basin is obviously controlled by accommodation space changes in sequence framework and basin evolution. As Faulting basin evolves into depression basin, both subsidence rate of basin basement and generation rate of accommodation space decrease vertically, it appears as a progradational reverse-graded sedimentary sequence, coal accumulation in secondary sequence framework intensifies first and then weakens, and coal accumulation at the middle stage of highstand system tract is the best. During steady rifting period, minable coal seams were mostly developed in initial lacustrine flooding surface of fourth-order sequence and at the middle-late period of highstand system tract, and coal accumulation center lay in palaeogeographic unit of delta plain with moderate available accommodation space. During shrinking period, minable coal seams gradually migrated to the maximum lacustrine flooding surface and coal accumulation center lay in palaeographical unit of lacustrine with large available accommodation space.展开更多
Western Yunnan is composed of several extruded continental microblocks that were generated by the oblique collision between the Indian and Asian continents during the Cenozoic.In this study,the magmatic and tectonic f...Western Yunnan is composed of several extruded continental microblocks that were generated by the oblique collision between the Indian and Asian continents during the Cenozoic.In this study,the magmatic and tectonic frameworks of western Yunnan in the Cenozoic were analyzed based on geochemistry,Sr-Nd-Pb isotopes,and apatite/zircon fission track dating.Magmatism during the Cenozoic in western Yunnan was then divided into three distinctive episodes：alkali granite rocks produced from 55 to 46 Ma were derived from the anatexis of crustal materials;bimodal igneous rocks formed between 37 and 24 Ma were possibly derived from an EMII mantle with a contribution from continental materials;and intermediate-basic volcanic rocks produced in the Tengchong microblocks since-16 Ma are considered to be generated by the partial melting of the upper mantle that was induced by the pulling apart of the dextral Gaoligong strike-slip fault system.Moreover,fission track analysis of apatite and zircon indicates that the regional crustal uplift in western Yunnan possibly began at -34 Ma,with accelerated annealing occurring at -24 Ma,-13 Ma,and -4 Ma.During the past24 Ma,the average denudation rate was -0.32 mm/yr for the faulted block controlled by the Chongshan-Lancang River fault.However,crustal uplift has been relatively gentle in places lacking influence from strike-slip shear zones,with an average denudation rate of-0.2 mm/yr.Combined with strike-slip shear and block rotation in the Cenozoic,the tectonic evolution of western Yunnan since -45Ma can thus be divided into four stages occurring at 45-37 Ma,37-24 Ma,24-13 Ma,and 13-0 Ma.展开更多
基金funded by Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(2020CX050103).
文摘Research on the distribution and development of black shales in the Lianggaoshan Formation has been deficient,which has hindered exploration for lacustrine shale oil in the Sichuan Basin.Our study characterized the well logging data,core samples,outcrops,and geochemistry of black shales in the Lianggaoshan Formation in the Sichuan Basin.Our analysis focused on the lake basin evolution and the migration characteristics,paleoenvironmental features,formation mechanisms,and developmental model of the black shales.The results indicated that black shales in the Lianggaoshan Formation exhibited significant lateral migration,with an overall thickening trend from east to west.Within the 1st Member of the formation,black shale occurred as a single thick layer in the eastern region that gradually thinned toward the central region.Multiple sets of shale developed within the 2nd and 3rd members,and these had lower thicknesses than the 1st Member and migrated toward central Sichuan.Paleoproductivity and terrigenous input were the main factors controlling the deposition of black shales.A semi-humid climate influenced the deposition of black shales,bringing abundant freshwater,terrigenous debris,and nutrients into the basin.Decomposition of organic matter consumed oxygen in sediment and bottom water,causing localized oxygen deficiency in the strata.
基金granted by the National Natural Science Foundation of China(Grant No.4187121&41630207)the Basic Scientific Research Projects of the Chinese Academy of Geological Sciences(Grant Nos.A1903、JYYWF20180903&JYYWF20182103)the work project of Chinese Geological Survey(Grant Nos.DD20160022、DD20160169、12120115026901&DD20190006)
文摘Based on the field outcrops surveyed,combined with recent published the regional tectonic evolution and geochronology data,we analyzed the lithologies and rock associations of strata,identified the sedimentary facies types,and discussed the distribution sedimentary facies and the hydrocarbon accumulation in the eastern Qiangtang basin during the Late Triassic–Jurassic.Marked by regional unconformities,there are two tectono-stratigraphic units(from the Carnian to the Norian and from the Rhaetian to the Kimmeridgian,respectively)in the eastern part of Qiangtang basin.We systematically described the distribution range,thickness variation and lithological characteristics of different formations in the tectonostratigraphic units.The Late Triassic-Jurassic is dominated by marine facies and marine-continental transitional facies.The marine-continental transitional facies include deltaic and tidallagoon facies.Marine facies including gentle carbonate slope,evaporative platform,restricted platform,littoral,neritic,bathyal and abysmal facies.The Carnian stage is dominated by littoral–neritic–bathyal–abysmal facies in the north Qiangtang depression otherwise the littoral–neritic facies in the south Qiangtang depression.The early Norian stage is dominated by carbonate gentle slope-mixed continental shelf facies.The late Norian,Bajocian,Callovian and Kimmeridgian stage are dominated by tidal flat-delta facies in the north Qiangtang depression and littoral-neritic facies in the south Qiangtang depression.The Bathonian and Oxfordian stage are dominated by evaporative platform-restricted platform-mixed continental shelf facies.The sedimentary facies formed zones from north to south and extended in an E–W direction.The Eastern Lower Uplift(ELU)played an important role in the division zones of sedimentary facies from north to south.During the Bathonian and Oxfordian,the ELU developed below the sea level and controlled the distribution of restricted platform,evaporative platform and platform margin.We analyzed 20 source rock samples from the upper Triassic-Jurassic.The total organic carbon(TOC)value from Qoimaco,Buqu and Adula Formations.of late TriassicJurassic in the eastern Qiangtang basin are ranges from 0.17~0.33%(average 0.28%),0.05~0.25%(average 0.15%)and 10.32~28.78%(average 19.33%),respectively.Obviously,the Adula Fm.developed good source rocks.The values of Tmax and S1+S2 in the Adula formation are 459-461℃(average 460℃)and 6.75-28.55 mg/g(average 18.18 mg/g),indicating that the Adula source rock has reached high-over-maturity stage.The bathyal,gentle slop and platform facie belts of the Upper Triassic can configurate the good hydrocarbon prospects in the northeastern area of the Qiangtang basin.
基金Supported by the National Natural Science Foundation of China(U1663204)National Major Oil and Gas Project(2016ZX05014002-007)。
文摘Based on a large number of geological and geophysical data,the formation,fracture-caves types and hydrocarbon distribution of hoodoo-upland on the Ordovician karst slope in the Tahe area,Tarim Basin,are discussed by analyzing faults and strata thickness.The hoodoo-upland was made of high peaks and narrow valleys in the Ordovician karst slope during the Early Hercynian karst period,which were distributed along the NNE positive flower structure and had inherited evolution.The fault-fractures and fracture-vugs complex were extremely developed,with a thickness of 100 m.The cumulative oil production of 60% oil wells was more than 20×10^(4) t per well in the hoodoo-upland,where the residual thickness of the Ordovician Yingshan Formation was greater than karst depressions.Caves formed by the shelter of collapsed breccias were developed in the valleys.They were 1.6 to 13.5 m high,with a filling rate of 51.6%.The positive flower structure under the settings of strike-slip compression controlled the early formation of the hoodoo-upland on the karst slope,resulting in the differences of drainage distribution and karstification.Compared with the water-rich karst valley,the hoodoo-upland with lean water suffered weaker karstification,had thicker residual stratum,and was higher in terrain.In rainy season,the meteoric water flew and corrode along the cracks,forming a complex network of fractures and caves.Combined with inherited uplift and the effective match of the NNE deep faults,oil and gas continuously charged into the reservoir space in the upland,forming the hoodoo fracture-cave reservoir with vertically quasi continuous distribution,high hydrocarbon abundance and high production.
文摘Since the1990s,China has become a net importer of petroleum(including crude and refined oil).The new century has seen the country more dependent upon imported oil at a higher price.This has drew attention both from abroad and domestic.This article tries to analyze the factors that affect the volume of import,the influence of import upon the economy development and energy security and deal with issues
文摘(from No.4, 2012 )Countermeasures for more oil and gas imports China’s imports of oil and gas may both take the lead in the world A rapid increase of petroleum consumption in China is almost inevitable and any attempt to slow the pace would sure face difficulties. According to BP’s Statistical Review of World Energy, the crude
文摘Economy growth in China is expected to slow down a little during the I3th Five-Year-Plan period. So will the domestic gas demand and supply market, which may be quite different from that of the 11 th and 12th Five-Year-Plan periods. The paper summarized the state quo of gas supply and demand in the country and analyzed factors that may affect the demand and supply balance in the new period. It is proposed that there will be many uncertainties in achieving supply and demand goals of gas set for tire period, and gas glut is also very possible during the time. To deal with the problem, it is suggested that several measures be taken nationwide： improving utilization of gas in several sectors, straightening and optimizing the pricing mechanism, speeding up construction of infrastructures, implementing relevant policies and boosting up supen^ision and monitor of tire industry.
基金sponsored by the National Natural Science Foundation of China(42002181)projecta public bidding project of 2020 Shanxi Provincial Science and Technology Program(20201101002-03).
文摘In-situ stress is a critical factor influencing the permeability of coal reservoirs and the production capacity of coalbed methane(CBM)wells.Accurate prediction of in-situ stress and investigation of its influence on coal reservoir permeability and production capacity are significant for CBM development.This study investigated the CBM development zone in the Zhengzhuang area of the Qinshui Basin.According to the low mechanical strength of coal reservoirs,this study derived a calculation model of the in-situ stress of coal reservoirs based on the multi-loop hydraulic fracturing method and analyzed the impacts of initial fractures on the calculated results.Moreover,by combining the data such as the in-situ stress,permeability,and drainage and recovery data of CBM wells,this study revealed the spatial distribution patterns of the current in-situ stress of the coal reservoirs and discussed the impacts of the insitu stress on the permeability and production capacity.The results are as follows.(1)Under given fracturing pressure,longer initial fractures are associated with higher calculated maximum horizontal principal stress values.Therefore,ignoring the effects of the initial fractures will cause the calculated values of the in-situ stress to be less than the actual values.(2)As the burial depth increases,the fracturing pressure,closure pressure,and the maximum and minimum horizontal principal stress of the coal reservoirs in the Zhengzhuang area constantly increase.The average gradients of the maximum and minimum horizontal principal stress are 3.17 MPa/100 m and 2.05 MPa/100 m,respectively.(3)Coal reservoir permeability is significantly controlled by the magnitude and state of the current in-situ stress.The coal reservoir permeability decreases exponentially with an increase in the effective principal stress.Moreover,a low lateral pressure coefficient(less than 1)is associated with minor horizontal compressive effects and high coal reservoir permeability.(4)Under similar conditions,such as resource endowments,CBM well capacity is higher in primary structural coal regions with moderate paleotectonic stress modification,low current in-situ stress,and lateral pressure coefficient of less than 1.
文摘China is abundant in unconventional gas, and stunning growth of gas reserves and production therefore can be expected in foreseeable future because of the exploration and development of the gas. For the next 5 to 10 years, conventional gas will still dominate energy market but in a long run, its influence will weaken gradually as unconventional gas kicks in and expands. Though the exploration and development of unconventional gas in China is still at a very early stage, three Chinese oil majors have already assessed the resources, including tight gas, coal-bed methane, shale gas and gas hydrate.
基金financially supported by the National Major Science and Technology Project of China(No.2016ZX05004-004)the State Scholarship Grant from the China Scholarship Council(CSC)to Yinggang Zhang。
文摘The ocean crust remnants of the Proto-Tethys were preserved as the Kudi ophiolites in the West Kunlun Orogenic Belt(WKOB),and its evolutionary history was mainly constructed by research on igneous or metamorphic rocks in the WKOB.Sedimentary rocks in the WKOB received little attention in the past;however,they could provide important constraints on the evolution of the oceanic lithosphere.Here,a series of shales and greywackes found in the Kudi area of WKOB were studied to constrain their deposition ages and explore their significance in the evolution of the ProtoTethys oceanic crust.The U-Pb dating and europium anomaly(Eu/Eu^(*))were analyzed for detrital zircons from greywackes interlayers,while bulk rare earth elements and yttrium(REY)of the shales were measured.Detrital zircons U-Pb ages yield a maximum deposition age of 436 Ma for the greywackes and black shales,while the REY distribution patterns of the black shales are similar to those of the Tarim Ordovician Saergan shales.Accordingly,the studied WKOB black shales were deposited in the Proto-Tethys Ocean during the Late Ordovician-Early Silurian period.The maximum deposition age at 436 Ma may represent a minimum closure time of the Proto-Tethys Ocean,which is also supported by the absence of increases in Eu/Eu^(*)values during the Late Ordovician-Early Silurian.Besides,our Eu/Eu^(*)values in detrital zircons indicate diminished orogenesis during the Archean to Meso-Proterozoic,subduction-related accretion at the margins of the supercontinent Rodinia during the Neoproterozoic.
基金supported by the National Natural Science Foundation of China(Grant No.42402171)the China Postdoctoral Science Foundation(Grant No.2023MD744255)+6 种基金the Natural Science Basic Research Program of Shaanxi(Grant No.2024JC-YBQN-0353)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.23JK0600)the Shaanxi Postdoctoral Science Foundation(Grant No.2023B SHEDZZ324)the project of Theory of Hydrocarbon Enrichment under Multi-Spheric Interactions of the Earth(Grant No.THEMSIE04010107)the Key Research and Development Program of Shaanxi(Grant No.2021KW-10)the Innovation Capability Support Program of Shaanxi(Grant No.2022PT-08)the SINOPEC CCUS Fund Project(Grant No.33550000-22-ZC0613-0326)。
文摘During the CO_(2)injection and geological storage process,the integrity of the cap rock significantly influences the long-term safety of CO_(2)storage.Natural fractures within the cap rock serve as potential pathways for CO_(2)migration,thereby increasing the risk of CO_(2)leakage.In this study,we determined the types,developmental characteristics,permeability changes,and CO_(2)-H_(2)O-Rock reactions of natural fractures in the mudstone cap rocks of the Sanduo Formation(E_(3)s)and Dainan Formation(E_(2)d)in the Gaoyou Sag of the Subei Basin using core observations,thin-section analysis,rock mechanics experiments,and paleomagnetic directional analysis.We identified four tectonic fracture sets(NNW,NWW,EW,and NE);high-angle shear fractures,ranging from 60°to 90°(average 82°)and typically measuring4-12 cm(average 7.5 cm),dominate the assemblage,while slip fractures,ranging from 32°to 50°(average 36°)and measuring 3-6 cm(average 3.9 cm),are also present.At the microscale,shear fractures average 160μm,and bedding fractures average 82μm.Notably,85.78%of shear fractures are unfilled,with calcite filling observed in 14.22%,while other fracture types show no filling.Permeability tests on samples without fractures reveal that permeability declines rapidly below 9 MPa,especially in shallower samples,followed by a slower reduction between 9 and 13 MPa,and ultimately stabilizes at approximately 0.00003 mD.In contrast,samples with fractures exhibit permeability that is 3-4 orders of magnitude higher;their fracture permeability decays according to a power law with pressure yet remains above 10 mD even at 46 MPa.Fractures with larger dip angles and those aligned with the maximum principal stress demonstrate the highest permeability.While silicate-filled fractures exhibit negligible changes in permeability,carbonate-filled fractu res experience a temporary enhancement due to dissolution;however,subsequent permeability remains controlled by factors such as effective stress and fracture orientation.
基金supported by the National Natural Science Foundation of China (40672086)the Ministry of Science and Technology "973" Project (2006CB701400)the Ministry of Land and Resources (XQ2004-06)
文摘The tectonic event during Cretaceous and its relationship with hydrocarbon accumulation in the Qiangtang Basin is discussed based on zircon U-Pb dating and the study of deformation, thermochronology and hydrocarbon formation. LA-ICPMS zircon U-Pb dating indicates that the tectonic event took place during the Early-Late Cretaceous （125-75Ma）. The event not only established the framework and the styles of structural traps in the basin, but also led to the cessation of the first hydrocarbon formation and the destruction of previous oil pools. The light crude oil in the basin was formed during the second hydrocarbon formation stage in the Cenozoic, and ancient structural traps formed during the Cretaceous event are promising targets for oil and gas exploration.
文摘Great volumes of shallow-buried （〈2,000 m） natural gases which are mainly composed of biogases and low-mature gases have been found in the Mesozoic-Cenozoic sedimentary basins in China. Many shallow gas reservoirs in China are characterized by coexistence of biogas and low-mature gas, so identifying the genetic types of shallow gases is important for exploration and development in sedimentary basins. In this paper, we study the gas geochemistry characteristics and distribution in different basins, and classify the shallow gas into two genetic types, biogas and low-mature gas. The biogases are subdivided further into two subtypes by their sources, the source rock-derived biogas and hydrocarbon-derived biogas. Based on the burial history of the source rocks, the source rock-derived biogases are divided into primary and secondary biogas. The former is generated from the source rocks in the primary burial stage, and the latter is from uplifted source rocks or those in a secondary burial stage. In addition, the identifying parameters of each type of shallow gas are given. Based on the analysis above, the distributions of each type of shallow gas are studied. The primary biogases generated from source rocks are mostly distributed in Quaternary basins or modem deltas. Most of them migrate in watersoluble or diffused mode, and their migration distance is short. Reservoir and caprock assemblages play an important role in primary biogas accumulation. The secondary biogases are distributed in a basin with secondary burial history. The oil-degraded biogases are distributed near heavy oil pools. The low-mature gases are widely distributed in shallow-buried reservoirs in the Meso-Cenozoic basins.
基金Supported by the China National Science and Technology Major Project(2017ZX05001-004,2016ZX05046-006)Petrochina Science and Technology Major Project(2019E-2601,2019E-2602)。
文摘By using the latest geological,seismic,drilling and logging data,this article studies the basic conditions for the formation of the total petroleum system and the orderly coexisting characteristics and accumulation models of conventional&unconventional reservoirs in the Lower Permian Fengcheng Formation in the Junggar Basin.Controlled by thermal evolution,hydrocarbon generation and expulsion process of the high-quality source rocks in alkaline lake as well as the characteristics of multi-type reservoirs(conglomerate,sandstone,dolomite and shale),conventional structure-lithologic reservoirs and tight oil and shale oil reservoirs controlled by source-reservoir structure have been formed.On the plane,mature conventional reservoirs,medium-high mature tight oil,and medium-high mature shale oil reservoirs coexist orderly from the slope area around Mahu sag to the sag.Based on the orderly coexisting characteristics of conventional and unconventional reservoirs in the Fengcheng Formation,it is clear that oil and gas in the Fengcheng Formation accumulate continuously over a large area in three accumulation models:integrated source-reservoir,source-reservoir in close contact,and separated source-reservoir model.The three accumulation models differ in relationship between source-reservoir structure,reservoir lithology and spatial distribution,hydrocarbon migration,oil and gas type.It is pointed out that the conventional&unconventional oil and gas should be explored and developed as a whole to achieve an overall breakthrough of the total petroleum system.This study is expected to enrich the geological theory of oil and gas enrichment in continental basins and to provide an analogy for exploration and research in other hydrocarbon-rich sags.
基金Projects OF06142 supported by the National Basic Research Program of China2001CB209100 by the Science Foundation of China University of Mining and Technology
文摘The study area is located in the south of Huanxian county,in Yan'an and Puxian counties and to the north of Xi'an.The Shanxi and lower Shihezi formations are important gas-bearing formations.Given our analysis of the direction of rivers,the contents of stable heavy minerals and of feldspar of palaeo river systems,the study area is divided into six palaeodrainage patterns corresponding to six feldspar regions and six sedimentary facies regions.On this basis,the distribution of sedimentary facies was also analyzed.During the Shanxi stage,a delta front was deposited in the Huanxian region and delta plains and fronts were deposited in the Pingliang,Chunhua-Yaoxian and Hancheng-Chengcheng regions.In the Yan'an-Daning region,only a delta front was developed.The distribution of sedimentary facies in the earlier Shihezi stage originated from the Shanxi stage.A delta front was developed in the Huanxian region while a delta plain and front developed in the Pingliang-Zhenyuan region during the same time.Lakes originated only in the Zhenyuan-Huanxian-Huachi-Zhengning and Daning-Jixian zones.This analytical method shows that different palaeodrainage patterns can be effectively distinguished in order to forecast sedimentary facies.
文摘Rare earth element compositions of Lower Ordovician dolomites in the Central and Northern Tarim Basin are studied. Most dolomite samples are more or less contaminated by clay minerals. Their rare earth element compositions have been consequently changed, showing both seawater-like and non-seawater-like features. The clay contamination should be disposed before the REE data are used. Through ICP-MS and ICP-AES analyses, the REE features are well documented. The clay contamination is quantitatively determined by microscopic investigation, trace elements and REE contents. The dolomites, at least in the Tarim Basin, are thought to be pure when their total LREE contents are less than 3×10^-6. Through comparison, the pure dolomites show similarities in REE patterns but differences in REE contents with co-existing pure limestone, which indicates that dolomitization may slightly change the REE compositions. Nevertheless, whatever the change is, the pure dolomites may act as a potential REE proxy for Ordovician seawater, which would be significant for ancient massive dolomite strata that lack limestone.
基金financially supported jointly by the National"95"Key Science and Technology Research Program(Grant No.99-110-01-03)the National Natural Science Foundation of China(Grant No.40572085)the New-century Excellent Talent Program of the Ministry of Education(Grant No.NCET-06-0204).
文摘The Central Gas Field is a famous large-sized gas field in the Ordos Basin of China. However, identification of main gas sources of the Ordovician reservoirs in this gas field remains puzzling. On the basis of a lot of geochemical data and geological research on natural gases, the characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin were studied. The results indicated that natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin have similar chemical and isotopic compositions to highly mature and over-mature dry gases. Both coal-derived gases and oil-type gases coexist in the Central Gas Field in the Ordos Basin. The former was derived mainly from Carboniferous-Permian coal measures and the latter from Lower Paleozoic marine carbonates. It is suggested that coal-derived gases occur in the eastern part of the Central Gas Field while oil-type gases may be produced mainly in the northern, western and southern parts of the Central Gas Field in the Ordos Basin.
基金supported by the work project of China Geological Survey(No.12120115002001-4,12120115026901)the Science Research from the Northwest Oilfield Sub–company of SINOPEC(No:KY2013–S–024)+1 种基金a Special Research Grant from Ministry of Land and Resources of the People’s Republic of China(No.201011034)the Innovation Group of National Natural Science Foundation of China(No.40921001)
文摘The formation and evolution of basins in the China continent are closely related to the collages of many blocks and orogenic belts. Based on a large amount of the geological, geophysical, petroleum exploration data and a large number of published research results, the basement constitutions and evolutions of tectonic-sedimentary of sedimentary basins, the main border fault belts and the orogenesis of their peripheries of the basins are analyzed. Especially, the main typical basins in the eight divisions in the continent of China are analyzed in detail, including the Tarim, Ordos, Sichuan, Songliao, Bohai Bay, Junggar, Qiadam and Qiangtang basins. The main five stages of superimposed evolutions processes of basins revealed, which accompanied with the tectonic processes of the Paleo-Asian Ocean, Tethyan and Western Pacific domains. They contained the formations of main Cratons （1850-800 Ma）, developments of marine basins （800-386 Ma）, developments of Marine- continental transition basins and super mantle plumes （386-252 Ma）, amalgamation of China Continent and developments of continental basins （252-205 Ma） and development of the foreland basins in the western and extensional faulted basin in the eastern of China （205~0 Ma）. Therefore, large scale marine sedimentary basins existed in the relatively stable continental blocks of the Proterozoic, developed during the Neoproterozoic to Paleozoic, with the property of the intracontinental cratons and peripheral foreland basins, the multistage superimposing and late reformations of basins. The continental basins developed on the weak or preexisting divisional basements, or the remnant and reformed marine basins in the Meso-Cenozoic, are mainly the continental margins, back-arc basins, retroarc foreland basins, intracontinental rifts and pull-apart basins. The styles and intensity deformation containing the faults, folds and the structural architecture of regional unconformities of the basins, responded to the openings, subductions, closures of oceans, the continent-continent collisions and reactivation of orogenies near the basins in different periods. The evolutions of the Tianshan-Mongol-Hinggan, Kunlun-Qilian-Qinling-Dabie-Sulu, Jiangshao-Shiwandashan, Helanshan-Longmengshan, Taihang-Wuling orogenic belts, the Tibet Plateau and the Altun and Tan- Lu Fault belts have importantly influenced on the tectonic-sedimentary developments, mineralization and hydrocarbon reservoir conditions of their adjacent basins in different times. The evolutions of basins also rely on the deep structures of lithosphere and the rheological properties of the mantle. The mosaic and mirroring geological structures of the deep lithosphere reflect the pre-existed divisions and hot mantle upwelling, constrain to the origins and transforms dynamics of the basins. The leading edges of the basin tectonic dynamics will focus on the basin and mountain coupling, reconstruction of the paleotectonic-paleogeography, establishing relationship between the structural deformations of shallow surface to the deep lithosphere or asthenosphere, as well as the restoring proto-basin and depicting residual basin of the Paleozoic basin, the effects of multiple stages of volcanism and paleo- earthquake events in China.
基金supported by the National Science and Technology Major Project (No. 2011ZX05043-005)Chinese Geological Survey based comprehensive geological research Project (No. 1212011120181)
文摘The Triassic Lower Karamay Formation（T2k1） is one of the main oil-bearing stratigraphic units in the northwestern margin of Junggar Basin（NW Junggar）, China. Based on an integrated investigation of outcrops, well logs and seismic data of NW Junggar, the Lower Karamay Formation is subdivided into 2 sets, 6 beds and 13 layers. Also, it is considered that the alluvial fan, the braided river, the meandering river and the shore-shallow lacustrine were developed during the early period of Middle Triassic in Karamay districts Ⅰ, Ⅲ. The Lower Karamay Formation deposits the following 9 sedimentary subfacies： the lower fan, the middle fan, the upper fan, the braided channel, the overflow bank, the river flood of braided river, the meandering channel, the river flood of meandering river, the shore-shallow lacustrine. Seventeen microfacies such as the braided stream channel, the alluvial sand floodplain, the alluvial glutenite floodplain, the water channel, the channel bar etc. have been identified in subfacies as well. The thickness of strata is firstly up-thinning and then thickening upward to the top, it is a process from large-scale lacustrine transgression to partly lacustrine regression. Furthermore, the microfacies planar distributing law proves that the remaining oil may enrich along the margin of microfacies because of the planar microfacies changes. Therefore, this research is beneficial for searching remaining oil in NW Junggar and providing information to the project ＂The Secondary Exploration＂ of PetroChina.
基金Supported by the State Key Scientific and Technological Program （2011 ZX05009-002） the National Natural Science Foundation （41002049） the Central University Basic Research Fund （2009QD12）
文摘To unveil formation mechanism of key sequence boundaries of inland faulting basin and coal accumulation charac- teristics of coal seams in isochrohal stratigraphic framework, sequence stratigraphy, palaeogeographic recovery and other methods were used to research the sequence stratigraphy and coal accumulation in the example of Banding Basn in the west margin of Yangtze Platform, and the authors advanced a coal accumulation model of Faulting basin on the basis of accommo- dation space changes in the background of palaeogeography of sequence framework. The results show that： normal lacustrine regression and forced lacustrine regression are the main driving forces for the formation of sequence boundaries of Faulting ba- sin; basement subsidence is the main source of accommodation space of Faulting basin; and subsidence disequilibrium is the main cause for the difference in generation rate of accommodation space of Faulting basin. Coal accumulation in Faulting basin is obviously controlled by accommodation space changes in sequence framework and basin evolution. As Faulting basin evolves into depression basin, both subsidence rate of basin basement and generation rate of accommodation space decrease vertically, it appears as a progradational reverse-graded sedimentary sequence, coal accumulation in secondary sequence framework intensifies first and then weakens, and coal accumulation at the middle stage of highstand system tract is the best. During steady rifting period, minable coal seams were mostly developed in initial lacustrine flooding surface of fourth-order sequence and at the middle-late period of highstand system tract, and coal accumulation center lay in palaeogeographic unit of delta plain with moderate available accommodation space. During shrinking period, minable coal seams gradually migrated to the maximum lacustrine flooding surface and coal accumulation center lay in palaeographical unit of lacustrine with large available accommodation space.
文摘Western Yunnan is composed of several extruded continental microblocks that were generated by the oblique collision between the Indian and Asian continents during the Cenozoic.In this study,the magmatic and tectonic frameworks of western Yunnan in the Cenozoic were analyzed based on geochemistry,Sr-Nd-Pb isotopes,and apatite/zircon fission track dating.Magmatism during the Cenozoic in western Yunnan was then divided into three distinctive episodes：alkali granite rocks produced from 55 to 46 Ma were derived from the anatexis of crustal materials;bimodal igneous rocks formed between 37 and 24 Ma were possibly derived from an EMII mantle with a contribution from continental materials;and intermediate-basic volcanic rocks produced in the Tengchong microblocks since-16 Ma are considered to be generated by the partial melting of the upper mantle that was induced by the pulling apart of the dextral Gaoligong strike-slip fault system.Moreover,fission track analysis of apatite and zircon indicates that the regional crustal uplift in western Yunnan possibly began at -34 Ma,with accelerated annealing occurring at -24 Ma,-13 Ma,and -4 Ma.During the past24 Ma,the average denudation rate was -0.32 mm/yr for the faulted block controlled by the Chongshan-Lancang River fault.However,crustal uplift has been relatively gentle in places lacking influence from strike-slip shear zones,with an average denudation rate of-0.2 mm/yr.Combined with strike-slip shear and block rotation in the Cenozoic,the tectonic evolution of western Yunnan since -45Ma can thus be divided into four stages occurring at 45-37 Ma,37-24 Ma,24-13 Ma,and 13-0 Ma.
