Hydrocarbon accumulation conditions and exploration targets of the Sinian Dengying Formation in the Southeastern Sichuan Basin

No breakthrough has been made in petroleum exploration of the Sinian Dengying Formation in the southeastern Sichuan Basin as the major factors controlling the hydrocarbon accumulation of the Dengying Formation have not been well established,including the development period and distribution of the platform margin,the effectiveness of the source-reservoir combination and the reliability of the Cambrian pre-salt structural trap.Based on the interpretation of seismic data and hydrocarbon-source correlation,the distribution of the platform margin of the Sinian Dengying Formation in the southeastern Sichuan Basin was mapped.Moreover,the gas source rocks of the Dengying Formation were clarified according to geochemical characteristics of fluid inclusions,and the pre-salt structures were further confirmed by seismic forward modeling and experiments of prestack depth migration.Results showed that the sedimentary facies of the 4th member of Dengying Formation in the southeastern Sichuan Basin was platform margin of gentle slope type.The platform margin reservoir of the Dengying Formation and the Lower Cambrian source rocks constitute a favorable source-reservoir combination.The carbon isotope characteristics of gas in fluid inclusions indicate that some of the oil/gas in the Dengying Formation were contributed by the Doushantuo Formation source rocks.As the difference in seismic velocities between carbonate rocks and gypsum/salt beds may cause a reduction in the amplitude of pre-salt structures,the low-amplitude structures identified on current seismic profiles are underestimated instead of overestimated.Accordingly,the Sinian structural traps are confirmed to develop in the deep pre-salt sequences in the low-steep anticline belt,southeastern Sichuan Basin.On the basis of the above new understanding,we propose two types of hydrocarbon migration modes for the Sinian Dengying Formation in southeastern Sichuan Basin,including lateral migration of hydrocarbons generated from the Cambrian Qiongzusi Formation and vertical migration of hydrocarbons derived from the Sinian Doushantuo Formation.Lithologic traps at the platform margin and pre-salt structural traps within the platform are favorable targets for natural gas exploration.

镍基与铜基碳化硅复合镀层制备技术发展现状

碳化硅(SiC)纳米复合镀层可以改善材料的耐磨性能,是代硬铬电镀的理想替代技术,本文对SiC复合电镀广泛使用的Ni基及Cu基复合电沉积制备工艺在耐磨方面的应用进行了概述,对Ni、Cu单金属及其合金为主的基质金属进行了评价和总结,在此基础上,重点综述了近年来SiC复合电沉积技术的研究进展,包括单一SiC颗粒及与其他复合颗粒沉积,对其中的规律进行了总结。最后展望了SiC复合电沉积技术的发展方向。

Extensional tectonics and North China Craton destruction:Insights from the magnetic susceptibility anisotropy(AMS)of granite and metamorphic core complex

The craton is a long-lived stable geologic unit on the Earth’s surface.However,since the Mesozoic,the North China Craton(NCC)experienced large-scale lithospheric removal,the fundamental change of physical and chemical characteristics of the lithospheric mantle,widely distributed crustal deformation,and extensive magmatism.This complex evolution contrary to other cratons is called the NCC destruction.Widespread magmatism in the eastern NCC is an important response to the lithospheric removal at depth and crustal deformation on the surface.The plutons emplace under a tectonic context and therefore record the information of the tectonics;especially,the anisotropy magnetic susceptibility(AMS)pattern of the pluton was acquired with the influence of regional stress.In the past fifteen years,about 22 plutons intruding during the different periods from the Late Triassic to the late stage of the Early Cretaceous have been studied with AMS.The emplacement mechanisms of plutons and the contemporary tectonic setting were discussed to constrain their relationship with the NCC destruction in different stages of magmatism.As a result,the Late Triassic,Early Jurassic,and Late Jurassic plutons exhibit consistent N(E)-S(W)trending magnetic lineations.The early stage of Early Cretaceous plutons display NW-SE trending magnetic lineations,while the late stage of Early Cretaceous plutons show magnetic lineations with various orientations.Combined with previous studies,it is concluded that the emplacements of the plutons intruding in these three stages were controlled by weak N(E)-S(W)trending extension,regional NW-SE trending extension,and weak extension in the shallow crustal level,respectively.The transformation of regional extension from the N(E)-S(W)to the NW-SE direction was accompanied by a strain-increasing tendency.The extensional tectonics in the eastern NCC was interpreted to represent the interaction between Mongol-Okhotsk belt,PaleoPacific plate,and eastern Eurasian continent.

Prototypes,modifications,and hydrocarbon enrichment variations in basins influenced by Tethyan evolution:A comparative analysis of the Persian Gulf Basin and the Sichuan Basin

The hydrocarbon accumulation modes and differences in the Tethyan realm serve as a hot research topic in the petroleum geology community at home and abroad.Both the Persian Gulf Basin in the Middle East and the Sichuan Basin in China,situated on the southern and northern sides of the Tethyan realm,respectively,record the whole geological process of the opening and closure of the Prototethys,the Paleotethys,and the Neotethys sequentially,exhibiting anomalous hydrocarbon enrichment.Based on the analysis of the plate tectonic evolution in the Tethyan realm,this study dissects the structures and hydrocarbon accumulation conditions of both basins.Followed by a systematic comparative analysis of the factors controlling hydrocarbon enrichment in the process of plate breakup and convergence in the Tethyan realm,this study proposes petroleum exploration targets in the realm.The results are as follows:(1)Since the Meso-Neoproterozoic,the Persian Gulf Basin and the Sichuan Basin have undergone similar tectonic evolution in the early stage but different in the late stage.Under the influence of the formation and evolution of the Prototethys,Paleotethys,and Neotethys oceans,both basins experienced multi-stage development and modification,forming two major extension-convergence cycles.Consequently,both basins are characterized by the vertical orderly superimposition of various basin prototypes in the order of rift-intracratonic basin(passive continental margin)-foreland.(2)The fact that the Tethyan realm was long located at medium-low latitudes and the local anoxic environment formed in the process of plate breakup and convergence played a vital role in the formation of extensive source rocks.The source rocks are predominantly distributed in underfilled rifts and deep depressions that were connected to the ocean in the unidirectional continental breakup process;basin-slopes and intra-shelf basins on passive continental margins;basinal lows within intracratonic basins,and underfilled foredeeps in foreland basins.The favorable areas for the formation of carbonate reservoirs include platform margins,submarine highs and paleo-uplifts within platforms,and fault zones.The evaporite cap rocks,intimately associated with the basin evolutionary stages and global dry-hot events,are critical for large-scale hydrocarbon preservation.(3)Under the influence of Tethyan evolution,the Persian Gulf Basin and the Sichuan Basin share similar primary factors controlling hydrocarbon enrichment.The moderate tectono-sedimentary differentiation and structural modification in the process of prototype basin superimposition,as well as the spatio-temporal matching of elements critical for hydrocarbon accumulation,are beneficial for the development of large oil and gas fields.The macroscopic hydrocarbon distribution is dictated by source rock-cap rock assemblages,while the local hydrocarbon distribution is governed by trap-reservoir assemblages.The critical factors determining the differential hydrocarbon enrichment in the Persian Gulf Basin and the Sichuan Basin include plate size and position,basement stability,eustatic movement,paleoclimate,and tectonic transformation.Besides,different tectonic modification intensities are closely related to the type,enrichment degree,and distribution of hydrocarbon reservoirs.

In-situ preparation of robust self-lubricating composite coating from thermally sprayed ceramic template

The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of mechanical properties due to a tribological design limit their practical applications.Here,a robust self-lubricating coating was fabricated by an in-situ synthesis of MoS_(2)/C within inherent defects of thermally sprayed yttria-stabilized zirconia(YSZ)coatings.The edge-pinning by noncoherent endows hybrid coatings with excellent interfacial strength,increasing their hardness(HV)and cohesive strength.Furthermore,owing to the formation of a well-covered robust lubricating film at a frictional interface,a coefficient of friction(COF)can be reduced by 79.6%to 0.15,and a specific wear rate(W)drops from 1.36×10^(−3) to 6.27×10^(−7) mm^(3)·N^(−1)·m^(−1).Combining outstanding mechanical properties and tribological performance,the hybrid coating exhibits great application potential in controlling friction and wear.Importantly,this strategy of introducing the target materials into the inherent defects of the raw materials to improve the relevant properties opens new avenues for the design and preparation of composite materials.

Chinese Economy under the New"Dual Circulation"Strategy:Challenges and Opportunities-A Summary of the Annual SUFE Macroeconomic Report(2020-2021)

Entering year 2020,the Chinese economy was struck by the COVID-19 outbreak.The unprecedented pandemic,entangled with the already elevated complexities in the nation's internal environment and external surroundings,aggravated its economic outlook.Internal factors including severe education mismatch in China's labor force,its vanishing demographic dividend,the declined purchasing power of its middle-income groups,risen leverage ratio of households and enterprises,and soared local government debt reinforced to weaken China's domestic demand.External factors,especially uncertainty in the China-US relation in the face of the re-shaping global value chain,dragged world economic recovery and thus China's exports and imports.This summary report highlights some major challenges and opportunities faced by the nation under its new development strategy that stresses internal circulation of domestic economy aided by its interaction with the globe.Our analyses based on IAR-CMM model provide a unified framework for addressing China's short-,medium-,and long-term issues in an internally coherent manner.Looking into year 2021,our benchmark projection reports an 8.4%annual real GDP growth rate.Alternative scenario analyses and policy simulations are conducted to assess the impacts of potential downside risks and the corresponding policy options for ensuring implicit targets.Through the lens of these analyses,we conclude that a refocus on effective management of internal demand,while deepening structural reforms on supply side and advancing orderly opening up,can help smooth the internal and external circulations of the Chinese economy to achieve high-quality development.

Multi-Directional and Multiphase Tectonic Modification,and Hydrocarbon Differential Enrichment in the Middle-Upper Yangtze Region

Based on the analysis of the deformation styles in different tectonic belts of the MiddleUpper Yangtze region,as well as the dissection of typical hydrocarbon reservoirs,this study determined the controlling effects of deformations on the hydrocarbon accumulations,obtaining the following results.The Middle-Upper Yangtze region experienced significant deformations during the Late Indosinian(T_(2)–T_(3)),the Middle Yanshanian(J_(3)–K_(1)),and the Himalayan,and five styles of tectonic deformations mainly occurred,namely superimposed deep burial,uplift,compressional thrusting,multi-layer decollement,and secondary deep burial.The distribution of hydrocarbon reservoirs in the piedmont thrust belts is controlled by the concealed structures on the footwall of the deep nappe.The gentle deformation area in central Sichuan experienced differential uplift,structural-lithologic hydrocarbon reservoirs were formed over a wide area.The eastern Sichuan-western Hunan and Hubei deformation area experienced Jura Mountains-type multi-layer detachment,compressional thrusting,and uplift.In relatively weakly folded and uplifted areas,conventional structural-lithologic hydrocarbon reservoirs have undergone adjustment and re-accumulation,and the shale gas resources are well preserved.In the strongly deformed areas,conventional hydrocarbon reservoirs were destroyed,while unconventional hydrocarbon reservoirs have been partially preserved.The marine strata in the Jianghan Basin experienced compression,thrusting,and denudation in the early stage and secondary deep burial in the late stage.Consequently,the unconventional gas resources have been partially preserved in these strata.Secondary hydrocarbon generation become favorable for conventional hydrocarbon accumulations in the marine strata.