Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the ...Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.展开更多
Controlled by fluctuating paleoclimates and sedimentary environments,the organic and inorganic features of the Lucaogou Formation exhibit strong heterogeneity in the vertical profile,challenging conventional geologica...Controlled by fluctuating paleoclimates and sedimentary environments,the organic and inorganic features of the Lucaogou Formation exhibit strong heterogeneity in the vertical profile,challenging conventional geological interpretation.To elucidate the possible influence of heterogeneity on resource evaluation,a high-resolution sampling approach was applied to an 86.2 cm long core from the Lucaogou Formation of the Jimsar sag in the Junggar Basin.86 sets of samples were micro-drilled from the core and subjected to comparative Rock-Eval pyrolysis.Following the classical guidelines,the organic abundance,kerogen type,and maturity of source rocks were exhaustively analyzed.Experimental results revealed that organic richness and composition vary significantly under different sedimentary backgrounds,which in turn leads to differential hydrocarbon generation.The combination of hydrocarbon generation,transport,and expulsion results in peculiar patterns for hydrocarbon accumulation in the Lucaogou Formation.Laminated shales in the Lucaogou Formation serve as both hydrocarbon source rocks and reservoirs,with laminae being migration pathways.Organic-rich dolomites in the Lucaogou Formation have a considerable hydrocarbon-generating capacity and present the characteristics of self-generation and self-storage.However,massive mudstones act purely as hydrocarbon source rocks.展开更多
This paper is a synthetic use of carbon isotope composition,Rock-Eval data,organic petrology,element composition of kerogen,major and trace elements,and biomarker characteristic of the Permian Pingdiquan(P_(2)p)source...This paper is a synthetic use of carbon isotope composition,Rock-Eval data,organic petrology,element composition of kerogen,major and trace elements,and biomarker characteristic of the Permian Pingdiquan(P_(2)p)source rocks in the Wucaiwan sag,Junggar Basin,China as proxies(1)for evaluations of hydrocarbon potential,organic matter(OM)composition and thermal maturity of the OM in the source rocks,(2)for reconstruction of paleodepositional environment,and(3)for analysis of controlling factor of organic carbon accumulation.The P_(2)p Formation developed good-excellent source rocks with thermal maturity of OM ranging from low-mature to mature stages.The OM was mainly composed of C_(3)terrestrial higher plants and aquatic organisms including aerobic bacteria,green sulfur bacteria,saltwater and fresh algae,Sphagnum moss species,submerged macrophytes,Nymphaea,and aquatic pollen taxa.The proportion of terrestrial higher plants decreased and that of aquatic organisms increased from margin to center of the sag.The benthic water within reducing environment and brackishwater column were superposed by periodic/occasional fresh-water influx(e.g.,rainfall and river drain),which led to fresh-water conditions and well oxygenating in the water column during overturn process.The whole study area developed lacustrine source rocks without seawater intrusion.During periodic/occasional fresh-water influx periods with plenty of terrestrial plant inputs,the paleoredox conditions of the sag were relatively oxic in the shallow fresh-water which experienced strong oxidation and decomposition of OM,therefore were not conducive for the OM preservation.However,the overall middle primary productivity made up for this deficiency,and was the main controlling factor on the organic carbon accumulation.A suitable supply from terrestrial inputs can promote biotic paleoproductivity,and a relatively high sedimentation rate can reduce oxidation and decomposition times of OM.On the contrary,during the intervals of the fresh-water influxes,relatively reducing conditions are a more important controlling factor on the OM accumulation in the case that the decrease of the terrestrial biotic source.展开更多
Coal pore parameters are closely related to macrolithotypes and coal structures,having a large influence over the gas potential and productivity of coalbed methane(CBM).The Middle Jurassic Xishanyao Formation,located ...Coal pore parameters are closely related to macrolithotypes and coal structures,having a large influence over the gas potential and productivity of coalbed methane(CBM).The Middle Jurassic Xishanyao Formation,located in the southern Junggar Basin of northwestern China,has geological conditions with rich CBM resources.The 46 Xishanyao coal samples gathered from the drilling cores and coal mines cover 4 types of macrolithotypes(bright coal 1,semi-bright coal 2,semi-dull coal 3,and dull coal 4)and 2 types of coal structures(primary coal I and cataclastic coal II).Based on a range of pore testing experiments and analytical methods,the dual effects of different macrolithotypes and coal structures on pore structures were intensely studied.The results showed that the specific surface area(SSA)and total pore volume(TPV)of coal samples increased gradually from bright to dull coals.For the same macrolithotypes,the SSA and TPV of the primary coals were lower than those of the cataclastic coals.Generally,the pore structures of bright and semi-bright coals are simpler when compared to semi-dull and dull coals with the same coal structure,whereas cataclastic coals have more complicated pore structure systems than primary coals with the same macrolithotypes.The bright and semi-bright coals have higher vitrinite contents and more endogenous fractures,whereas well-developed structural fractures were identified in cataclastic coals.Therefore,bright and semi-bright coals have better pore connectivity than semi-dull and dull coals with the same coal structure,the pore connectivity of cataclastic coals being slightly better than that of primary coals under the same macrolithotypes.In terms of the CBM adsorption conditions,the eight type samples formed a descending order:Ⅱ-4>I-4>Ⅱ-3>Ⅰ-3>Ⅱ-2>Ⅰ-2>Ⅱ-1>Ⅰ-1,while they ranked as follows when consideration was given to the CBM seepage capacities:II-2>Ⅱ-1>Ⅰ-2>Ⅰ-1>Ⅰ-3>Ⅰ-4>Ⅱ-3>Ⅱ-4.As a result,it could be determined that the bright and semi-bright coals had stronger adsorption capacities,whereas the cataclastic coals had better pore connectivity and seepage capacities.Pore structure characteristics should be analysed under the dual control of different macrolithotypes and coal structures,so that they can provide greater value for guiding CBM exploration and exploitation,as along for preventing underground gas accidents.展开更多
The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it i...The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.展开更多
The composition and sedimentary controlling effect of the coal measure gas-bearing(CMG)system of the Jurassic Xishanyao Formation in the southern margin of the Junggar Basin(SJB)are analysed based on core observations...The composition and sedimentary controlling effect of the coal measure gas-bearing(CMG)system of the Jurassic Xishanyao Formation in the southern margin of the Junggar Basin(SJB)are analysed based on core observations,sample tests,and logging data.The results show that the lithological associations of the SJB can be classified into 6 types based on sediment supply strengths and sealing abilities,while the gas shows of CMG reservoirs vary greatly among different lithological associations.Due to the diversified coal-forming environment and multistage coal accumulation,superimposed CMG systems are generally developed in the SJB,and their types include:superimposed unattached CMG systems,multilayer unified CMG systems,and superimposed mixed CMG systems.Furthermore,sedimentary controls on the vertical and regional distributions of different types of CMG systems are discussed according to the sedimentary facies of single wells and well cross-sections and the corresponding data of well log,gas logging,and gas contents.Shore shallow lake environments in the Fukang,Miquan,and northern Liuhuanggou areas were favourable for forming superimposed unattached CMG systems.Braided river environments in the Houxia and the southern Liuhuanggou areas usually formed multilayer unified CMG systems.Braided river delta environments in the Manasi,Hutubi,and eastern Sikeshu areas generally developed multilayer unified CMG systems and superimposed mixed CMG systems.For different types of superimposed CMG systems,the number of gas-bearing units,coal seam gas content,vertical hydraulic connectivity and lateral continuity vary considerably,which makes it necessary to tailor the CMG co-production plan to the type of CMG system.展开更多
1.Objective The Eastern Junggar Kalamaili region in Xinjiang constitutes a significant tin metallogenic belt in northwest China(Fig.1a).It hosts four independent tin deposits-Kamusite,Ganliangzi,Beilekuduke,and Saresh...1.Objective The Eastern Junggar Kalamaili region in Xinjiang constitutes a significant tin metallogenic belt in northwest China(Fig.1a).It hosts four independent tin deposits-Kamusite,Ganliangzi,Beilekuduke,and Sareshenke-from west to east,supplemented by two tin mineralized points,namely Hongtujingzi and Sujiquan(Figs.1b).according to the ore type and the composition of gangue minerals,the tin deposits in the region are classified into two groups:Quartz vein type and greisen type,with the Sareshenke deposit ascribed to the former and the remainder to the latter.展开更多
This study focuses on tuffaceous clastic rocks of the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin.It aims to explore the influence of sedimentation and parent rock on this kind of res...This study focuses on tuffaceous clastic rocks of the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin.It aims to explore the influence of sedimentation and parent rock on this kind of reservoir development.The results show that the tuffaceous components formed by the denudation of ultramafic and mafic rocks can transform into chlorite coating or hematite,while those from intermediate rock denudation can be dissolved or transformed into illite.Sedimentary facies and lithofacies are essential in controlling the evolutionary result of tuffaceous components.Matrix-supported medium conglomerate and grain-supported medium-fine conglomerate that developed in the fan delta plain,with a closed original geochemical systems,have been in the oxidizing environment for a long time.The tuffaceous matrices mainly transforms into hematite or illite.These minerals occupy the primary pores and are difficult to dissolve by felsic fluids,which inhibits the development of high-quality reservoirs.The grain-supported sandy fine conglomerate developed in the fan delta front was in the underwater reductive environment with an open original geochemical system.The tuffaceous matrices not only can transform into chlorite coating to strengthen the particle's compaction resistance,but also can be fully dissolved,which promotes the formation of high-quality reservoirs.展开更多
Research based on oil accumulation models is essential for exploring the hydrocarbon accumulation theory further.Studies on tight oil accumulation models focused on fan delta depositional systems,and in particular,sys...Research based on oil accumulation models is essential for exploring the hydrocarbon accumulation theory further.Studies on tight oil accumulation models focused on fan delta depositional systems,and in particular,systems involving source-reservoir separated type are scarce.To explore the accumulation model of tight oil in conglomerate,this study focused on the Permian-Triassic tight conglomerate oil in Mahu sag,Junggar Basin,using well drilling,well logging,seismic profiling,oil testing,and laboratory data,and analyzed the formation conditions,formation types,and distribution patterns of conglomerate reservoirs.The results show that,the conglomerate reservoirs are predominantly lithologic reservoirs and partly fault-lithologic reservoirs;there is no water evident at the edge or bottom around the reservoirs.The tight conglomerate layer in the delta plain subfacies of each fan exhibits high clay content and intense diagenesis,and the argillaceous rocks in the pro-fan delta subfacies and shallow lacustrine facies form the sealing and floor conditions.The sandy conglomerate of fan delta front subfacies is the main reservoir body.Additionally,strikeslip faulting in the Indosinian-Himalayan period formed an efficient faulting system for trans-stratal migration with Hercynian-Indosinian inverse faulting.Oil migration is driven by the overpressure caused by hydrocarbon generation from alkali lacustrine source rocks.The distribution of reservoirs is primarily controlled by the large fan bodies,namely the Zhongguai,Baijiantan,Karamay,Huangyangquan,Xiazijie,Xiayan,and Dabasong fans.Each fan body forms a group of reservoirs or oilfields,resulting in a widely distributed pattern,according to which reservoir and sealing constitute one whole body—i.e.,patterns of“one sand and one reservoir,one fan and one field.”This results in a quasi-continuous accumulation model,which includes strong oil charging,efficient faulting transportation,trans-stratal migration,and lithologic trapped accumulation.The proposed model is an important supplement to the existing model of quasi-continuous oil and gas accumulation.Overall,this study enriches unconventional oil and gas accumulation theories.展开更多
For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distr...For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distribution of major hydrocarbon source rocks.Based on the latest 3D seismic,gravity-magnetic,and drilling data,together with the results of previous structural physical simulation and discrete element numerical simulation experiments,the spatial distribution of pre-existing paleo-structures and detachment layers in deep strata of southern Junggar Basin were systematically characterized,the structural deformation characteristics and formation mechanisms were analyzed,the distribution patterns of multiple hydrocarbon source rock suites were clarified,and hydrocarbon accumulation features in key zones were reassessed.The exploration targets in deep lower assemblages with possibility of breakthrough were expected.Key results are obtained in three aspects.First,structural deformation is controlled by two-stage paleo-structures and three detachment layers with distinct lateral variations:the Jurassic layer(moderate thickness,wide distribution),the Cretaceous layer(thickest but weak detachment),and the Paleogene layer(thin but long-distance lateral thrusting).Accordingly,a four-layer composite deformation sequence was identified,and the structural genetic model with paleo-bulge controlling zonation by segments laterally and multiple detachment layers controlling sequence vertically.Second,the Permian source rocks show a distribution pattern with narrow trough(west),multiple sags(central),and broad basin(east),which is depicted by combining high-precision gravity-magnetic data and time-frequency electromagnetic data for the first time,and the Jurassic source rocks feature thicker mudstones in the west and rich coals in the east according to the reassessment.Third,two petroleum systems and a four-layer composite hydrocarbon accumulation model are established depending on the structural deformation strength,trap effectiveness and source-trap configuration.The southern Junggar Basin is divided into three segments with ten zones,and a hierarchical exploration strategy is proposed for deep lower assemblages in this region,that is,focusing on five priority zones,expanding to three potential areas,and challenging two high-risk targets.展开更多
Based on core and thin section data,the source rock samples from the Fengcheng Formation in the Mahu Sag of the Junggar Basin were analyzed in terms of zircon SIMS U-Pb geochronology,organic carbon isotopic compositio...Based on core and thin section data,the source rock samples from the Fengcheng Formation in the Mahu Sag of the Junggar Basin were analyzed in terms of zircon SIMS U-Pb geochronology,organic carbon isotopic composition,major and trace element contents,as well as petrology.Two zircon U-Pb ages of(306.0±5.2)Ma and(303.5±3.7)Ma were obtained from the first member of the Fengcheng Formation.Combined with carbon isotopic stratigraphy,it is inferred that the depositional age of the Fengcheng Formation is about 297-306 Ma,spanning the Carboniferous-Permian boundary and corresponding to the interglacial period between C4 and P1 glacial events.Multiple increases in Hg/TOC ratios and altered volcanic ash were found in the shale rocks of the Fengcheng Formation,indicating that multiple phases of volcanic activity occurred during its deposition.An interval with a high B/Ga ratio was found in the middle of the second member of the Fengcheng Formation,associated with the occurrence of evaporite minerals and reedmergnerite,indicating that the high salinity of the water mass was related to hydrothermal activity.Comprehensive analysis suggests that the warm and humid climate during the deposition of Fengcheng Formation is conducive to the growth of organic matter such as algae and bacteria in the lake,and accelerates the continental weathering,driving the input of nutrients.Volcanic activities supply a large amount of nutrients and stimulate primary productivity.The warm climate and high salinity are conducive to water stratification,leading to water anoxia that benefits organic matter preservation.The above factors interact and jointly control the enrichment of organic matter in the Fengcheng Formation of Mahu Sag.展开更多
Taking the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin as an example,the influences of the burial process in a foreland basin on the diagenesis and the development of high-quality res...Taking the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin as an example,the influences of the burial process in a foreland basin on the diagenesis and the development of high-quality reservoirs of deep and ultra-deep clastic rocks were investigated using thin section,scanning electron microscope,electron probe,stable isotopic composition and fluid inclusion data.The Qingshuihe Formation went through four burial stages of slow shallow burial,tectonic uplift,progressive deep burial and rapid deep burial successively.The stages of slow shallow burial and tectonic uplift not only can alleviate the mechanical compaction of grains,but also can maintain an open diagenetic system in the reservoirs for a long time,which promotes the dissolution of soluble components by meteoric freshwater and inhibits the precipitation of dissolution products in the reservoirs.The late rapid deep burial process contributed to the development of fluid overpressure,which effectively inhibits the destruction of primary pores by compaction and cementation.The fluid overpressure promotes the development of microfractures in the reservoir,which enhances the dissolution effect of organic acids.Based on the quantitative reconstruction of porosity evolution history,it is found that the long-term slow shallow burial and tectonic uplift processes make the greatest contribution to the development of deep-ultra-deep high-quality clastic rock reservoirs,followed by the late rapid deep burial process,and the progressive deep burial process has little contribution.展开更多
The Carboniferous to Permian tectono-sedimentary evolution of the southern Junggar area brings new insights into understanding the subduction-collision processes in the northern Tianshan region.Integrating geophysics,...The Carboniferous to Permian tectono-sedimentary evolution of the southern Junggar area brings new insights into understanding the subduction-collision processes in the northern Tianshan region.Integrating geophysics,geochemistry,and geochronology approaches,this study investigates the Carboniferous-Permian strata in the southern Junggar Basin.The results have revealed three distinct tectono-stratigraphic evolutionary stages,each marked by a distinctive volcano-sedimentary sequence.The Early Carboniferous strata suggest intense volcanic activities in the southern Junggar area.During the Late Carboniferous,the southern Junggar Basin was controlled by normal faulting in an extensional setting,receiving sedimentary inputs from the Junggar terrane.The Lower Permian,unconformably overlying the Upper Carboniferous,was shaped by an extensional regime and is comprised by volcano-clastic sequences that received detritus from the Yili-Central Tianshan block.These findings indicate that a Late Carboniferous forearc basin developed in the southern Junggar area,and it evolved into a post-collisional rift in the Early Permian.This period marked a dynamic shift from bidirectional subduction(rollback)to the detachment of the North Tianshan oceanic slab.We propose that the collision between the YiliCentral Tianshan block and the Junggar terrane,along with the closure of the North Tianshan Ocean,likely occurred in the Late Carboniferous(ca.306-303 Ma).展开更多
Based on the organic geochemical data and the molecular and stable carbon isotopic compositions of natural gas of the Lower Permian Fengcheng Formation in the western Central Depression of Junggar Basin,combined with ...Based on the organic geochemical data and the molecular and stable carbon isotopic compositions of natural gas of the Lower Permian Fengcheng Formation in the western Central Depression of Junggar Basin,combined with sedimentary environment analysis and hydrocarbon-generating simulation,the gas-generating potential of the Fengcheng source rock is evaluated,the distribution of large-scale effective source kitchen is described,the genetic types of natural gas are clarified,and four types of favorable exploration targets are selected.The results show that:(1)The Fengcheng Formation is a set of oil-prone source rocks,and the retained liquid hydrocarbon is conducive to late cracking into gas,with characteristics of high gas-generating potential and late accumulation;(2)The maximum thickness of Fengcheng source rock reaches 900 m.The source rock has entered the main gas-generating stage in Penyijingxi and Shawan sags,and the area with gas-generating intensity greater than 20×10^(8) m^(3)/km^(2) is approximately 6500 km^(2).(3)Around the western Central Depression,highly mature oil-type gas with light carbon isotope composition was identified to be derived from the Fengcheng source rocks mainly,while the rest was coal-derived gas from the Carboniferous source rock;(4)Four types of favorable exploration targets with exploration potential were developed in the western Central Depression which are structural traps neighboring to the source,stratigraphic traps neighboring to the source,shale-gas type within the source,and structural traps within the source.Great attention should be paid to these targets.展开更多
Based on the theory of superimposed deformation and the regional tectonic background,the multi-phase non-coaxial superimposed structures in Junggar Basin were systematically analyzed using seismic interpretation,field...Based on the theory of superimposed deformation and the regional tectonic background,the multi-phase non-coaxial superimposed structures in Junggar Basin were systematically analyzed using seismic interpretation,field outcrop observation,and paleo-stress field recovery methods according to the characteristics of the current tectonic framework.Moreover,the tectonic evolution process of the basin was reconstructed using sandbox analogue modelling technology.The results showed that the study area has experienced five phases of non-coaxial deformation with superimposition:The first phase of deformation(D1)is characterized by NNE-SSW extension during late Carboniferous to early Permian,which formed large graben,half graben and other extensional structure style around the basin.The second phase of deformation(D2)is represented by NE-SW compression during the middle to late Permian,and it comprised numerous contraction structures that developed based on D1.The basic form of the entire basin is alternating uplift and depression.The third phase of deformation(D3)is the NW-SE transpressional strike-slip in the Triassic-Jurassic,which produced numerous strike-slip structural styles in the middle part of the basin.The fourth phase of deformation(D4)is the uniform sedimentation during Cretaceous,and the fifth phase(D5)is the compression along NNE-SSW due to the North Tianshan northward thrust,which produced three rows of fold thrust belts and tear faults in the front of the mountain in the southern margin of the basin.The newly established three-dimensional tectonic evolution model shows that,based on the large number of NW-trending grabens and half grabens in the Carboniferous basement of Junggar Basin,multiple level NE trending uplifts have formed with the joint superposition of the late structural inversion and multiple stress fields.This has resulted in the current tectonic units of alternating uplifts and depressions in different directions in the study area.展开更多
The combined petrographic,petrological,geochemical and geochronological study of the Neoproterozoic gneisses of the Sarychabyn and Baskan complexes of the Junggar Alataw of South Kazakhstan elucidate the Precambrian t...The combined petrographic,petrological,geochemical and geochronological study of the Neoproterozoic gneisses of the Sarychabyn and Baskan complexes of the Junggar Alataw of South Kazakhstan elucidate the Precambrian tectonic evolution of the Aktau–Yili terrane.It is one of the largest Precambrian crustal blocks in the western Central Asian orogenic belt.The U-Pb single-grain zircon ages indicate that granite-gneisses formed from the same source and crystallised in the early Neoproterozoic ca.930–920 Ma.The chemical composition of gneisses corresponds to A2-type granites.The whole-rock Nd isotopic characteristics(εNd(t)=−4.9 to−1.0 and TNd(DM-2st)=1.9 to 1.7 Ga)indicate the involvement of Paleoproterozoic crustal rocks in magma generation.Early Neoproterozoic ca.930–920 Ma A-type granitoids in the Aktau–Yili terrane of South and Central Kazakhstan might reflect within-plate magmatism adjacent to the collisional belt or a local extension setting in back-arc areas of the continental arc.展开更多
The mudstone,gray tuffite and carbonaceous shale in the Upper Carboniferous Batamayineishan Formation(Bashan Formation)are essential source rocks for the volcanic reservoir in eastern Junggar,northwestern China.The ke...The mudstone,gray tuffite and carbonaceous shale in the Upper Carboniferous Batamayineishan Formation(Bashan Formation)are essential source rocks for the volcanic reservoir in eastern Junggar,northwestern China.The kerogen components,vitrinite reflectance,Rock-Eval pyrolysis,lipid biomarkers and isotope compositions were measured to understand the provenance and depositional environment of Bashan Formation under the background of volcanic activities.There were 10 and 4 periods of volcanic eruptions identified in the wells CS and DZ,respectively.The source rocks developed in the late or intermittent phase of volcanic activity.The original island arcs of the Early Carboniferous evolved into the Wucaiwan sag and the Dishuiquan sag in the Bashan Formation.The Wucaiwan sag inherited the restricted,closed residual sea,which had a slightly anoxic and hypersaline environment.The Dishuiquan sag was generally an oxidizing lacustrine environment,influenced by a marine transgression that may have occurred at the end of the DZ_(Ⅲ)period during the Late Carboniferous.Although the total organic matter decreased due to the volcanic eruption,ash could cause an increase of aquatic organisms,coinciding with increases in salinity and reducibility in the Dishuiquan sag.展开更多
Overpressure is widely developed in deep petroliferous strata in the hinterland of the Junggar Basin.However,a comprehensive understanding of its origin and effect on hydrocarbon distribution and enrichment remains la...Overpressure is widely developed in deep petroliferous strata in the hinterland of the Junggar Basin.However,a comprehensive understanding of its origin and effect on hydrocarbon distribution and enrichment remains lacking.In this study,we employ five empirical methods and comprehensive geological analysis to identify the origin of overpressure,and uncover the effect of overpressure on hydrocarbon enrichment.The results indicate that disequilibrium compaction is not a significant factor in overpressure generation.Instead,hydrocarbon generation,pressure transfer and diagenesis are the primary causes.The empirical methods support this conclusion.There is a positive correlation between overpressure intensity and source rock thickness and maturity.Notably,widespread cross-formational migration of hydrocarbon bearing fluid occurred,with sandstone overpressure exceeding that of adjacent shale in non-source strata.Furthermore,there is a distinct transformation from smectite to illite near the top of overpressure.Hydrocarbon generation pressurization and pressure transfer significantly effect hydrocarbon enrichment.The overpressure caused by hydrocarbon generation drives hydrocarbon migration and accumulation,establishing an optimal energy configuration between reservoir and cap rock.Faults play a crucial role in hydrocarbon vertical migration and pressure relief.The overpressure in reservoirs can reduce the porosity and permeability thresholds and enhance the charging capacity of oil and gas.展开更多
The Jurassic coal-measure source rocks in the Junggar Basin have drawn considerable attention in recent years. In our hydrocarbon thermal simulation experiments of these rocks, we found that the dark mudstone evaluate...The Jurassic coal-measure source rocks in the Junggar Basin have drawn considerable attention in recent years. In our hydrocarbon thermal simulation experiments of these rocks, we found that the dark mudstone evaluated as good source rock, had a much lower hydrocarbon generation capacity than the coal and carbonaceous mudstone, evaluated as poor source rock. Based on this background, we performed Fourier transform infrared spectroscopy(FTIR) and combined the results of semi-open thermal simulation experiments to explore the association between the molecular structure and hydrocarbon production capacity, with the aim of obtaining a new understanding of hydrocarbon potential of Jurassic coal-measure source rocks from the perspective of molecular structure. The results indicate that coals exhibit lower condensation of aromatic structures and higher relative abundance of aliphatic structures with a higher degree of branched chaining than mudstones and carbonaceous mudstones. Apparent aromaticity(f_a), aromatic abundance parameter I, and degree of condensation(DOC) are negatively correlated with organic matter abundance. The aliphatic structural parameter H demonstrates a substantial positive correlation with organic matter abundance. Furthermore, aliphatic relative abundance factor A is associated with the type of organic matter;the better is the type of the organic matter, the larger is the A value. The combination of the molecular structures with the thermal simulation results shows that the aliphatic hydrogen enrichment of selected carbonaceous mudstone is similar to that of coal. However, the relative abundance of the aliphatic group of it is high, and the DOC of the aromatic structure is low, making the hydrocarbon generation base stronger and easier to crack. Thus, the hydrocarbon generation capacity of carbonaceous mudstone is slightly higher than that of coal. Mudstone has low H and I values, and the DOC is high, indicating that its hydrocarbon base is low, so it has low hydrocarbon generation capacity. Therefore, the molecular structure is closely associated with the hydrocarbon potential of coal-measure source rocks. When evaluating the qualities of coal-measure source rocks, the influence of molecular structure on these rocks should be considered.展开更多
The fine-grained sedimentary rocks have numerous bedding-parallel fractures that are essential for the migration,enrichment,and efficient development of oil and gas.However,because of their variety and the complexity ...The fine-grained sedimentary rocks have numerous bedding-parallel fractures that are essential for the migration,enrichment,and efficient development of oil and gas.However,because of their variety and the complexity of the factors that affect them,their spatial prediction by the industrial community becomes challenging.Based on sample cores,thin sections,and well-logging and seismic data,this study employed a multi-scale data matching approach to quantitatively predict the development of bedding-parallel fractures and investigate their spatial distribution.Bedding-parallel fractures in the Lucaogou Formation in Jimusar Sag frequently occur along preexisting bedding planes and lithological interfaces.Unfilled bedding-parallel fractures inside or near source-rocks exhibit enhanced oil-bearing capacity.They were identified on micro-resistivity scanning images by the presence of regularly continuous black or nearly black sinusoidal curves.Overall,the developmental degree of bedding-parallel fractures was positively related to the brittle mineral and total organic carbon contents and negatively related to single reservoir interval thickness.The maintained porosity of the reservoir matrix contributed to a thorough response to factors affecting the development of bedding-parallel fractures.Here,an effective and objective method was proposed for predicting the development and distribution of bedding-parallel fractures in the fine-grained sedimentary rocks.The method was based on the matched reservoir interval density,reservoir interval density,and matched sweet spot density of bedding-parallel fractures.The prediction method integrated the significant advantages of high vertical resolution from logging curves and strong lateral continuity from seismic data.The average relative prediction error was 8%in the upper sweet spot in the Lucaogou Formation,indicating that the evaluation parameters for bedding-parallel fractures in fine-grained sedimentary rocks were reasonable and reliable and that the proposed prediction method has a stronger adaptability than the previously reported methods.The workflow based on multi-scale matching and stepwise progression can be applied in similar fine-grained sedimentary rocks,providing reliable technological support for the exploration and development of hydrocarbons.展开更多
基金Supported by Leading Talent Program of Autonomous Region(2022TSYCLJ0070)PetroChina Prospective and Basic Technological Project(2021DJ0108)Natural Science Foundation for Outstanding Young People in Shandong Province(ZR2022YQ30).
文摘Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.
基金supported by the National Natural Science Foundation of China(No.U22B6004)the Basic Research and Strategic Reserve Technology Research Project of CNPC(No.2020D-5008-01)the Scientific Research and Technology Development Project of PetroChina Exploration&Development Research Institute(Nos.2021DJ0104 and 2021DJ1808)。
文摘Controlled by fluctuating paleoclimates and sedimentary environments,the organic and inorganic features of the Lucaogou Formation exhibit strong heterogeneity in the vertical profile,challenging conventional geological interpretation.To elucidate the possible influence of heterogeneity on resource evaluation,a high-resolution sampling approach was applied to an 86.2 cm long core from the Lucaogou Formation of the Jimsar sag in the Junggar Basin.86 sets of samples were micro-drilled from the core and subjected to comparative Rock-Eval pyrolysis.Following the classical guidelines,the organic abundance,kerogen type,and maturity of source rocks were exhaustively analyzed.Experimental results revealed that organic richness and composition vary significantly under different sedimentary backgrounds,which in turn leads to differential hydrocarbon generation.The combination of hydrocarbon generation,transport,and expulsion results in peculiar patterns for hydrocarbon accumulation in the Lucaogou Formation.Laminated shales in the Lucaogou Formation serve as both hydrocarbon source rocks and reservoirs,with laminae being migration pathways.Organic-rich dolomites in the Lucaogou Formation have a considerable hydrocarbon-generating capacity and present the characteristics of self-generation and self-storage.However,massive mudstones act purely as hydrocarbon source rocks.
基金financially supported by the National Natural Science Foundation of China(NSFC)(No.42202154)the Science Foundation of China University of Petroleum,Beijing(No.ZX20220074)。
文摘This paper is a synthetic use of carbon isotope composition,Rock-Eval data,organic petrology,element composition of kerogen,major and trace elements,and biomarker characteristic of the Permian Pingdiquan(P_(2)p)source rocks in the Wucaiwan sag,Junggar Basin,China as proxies(1)for evaluations of hydrocarbon potential,organic matter(OM)composition and thermal maturity of the OM in the source rocks,(2)for reconstruction of paleodepositional environment,and(3)for analysis of controlling factor of organic carbon accumulation.The P_(2)p Formation developed good-excellent source rocks with thermal maturity of OM ranging from low-mature to mature stages.The OM was mainly composed of C_(3)terrestrial higher plants and aquatic organisms including aerobic bacteria,green sulfur bacteria,saltwater and fresh algae,Sphagnum moss species,submerged macrophytes,Nymphaea,and aquatic pollen taxa.The proportion of terrestrial higher plants decreased and that of aquatic organisms increased from margin to center of the sag.The benthic water within reducing environment and brackishwater column were superposed by periodic/occasional fresh-water influx(e.g.,rainfall and river drain),which led to fresh-water conditions and well oxygenating in the water column during overturn process.The whole study area developed lacustrine source rocks without seawater intrusion.During periodic/occasional fresh-water influx periods with plenty of terrestrial plant inputs,the paleoredox conditions of the sag were relatively oxic in the shallow fresh-water which experienced strong oxidation and decomposition of OM,therefore were not conducive for the OM preservation.However,the overall middle primary productivity made up for this deficiency,and was the main controlling factor on the organic carbon accumulation.A suitable supply from terrestrial inputs can promote biotic paleoproductivity,and a relatively high sedimentation rate can reduce oxidation and decomposition times of OM.On the contrary,during the intervals of the fresh-water influxes,relatively reducing conditions are a more important controlling factor on the OM accumulation in the case that the decrease of the terrestrial biotic source.
基金supported by the National Natural Science Foundation of China(Grant No.42102223)the Chinese Postdoctoral Science Foundation(Grant Nos.2021M693844,2022T150284)+1 种基金the Chinese Geological Survey Project(Grant No.DD20160204-3)the discipline innovation team of Liaoning Technical University(Grant Nos.LNTU20TD-14,LNTU20TD-30)。
文摘Coal pore parameters are closely related to macrolithotypes and coal structures,having a large influence over the gas potential and productivity of coalbed methane(CBM).The Middle Jurassic Xishanyao Formation,located in the southern Junggar Basin of northwestern China,has geological conditions with rich CBM resources.The 46 Xishanyao coal samples gathered from the drilling cores and coal mines cover 4 types of macrolithotypes(bright coal 1,semi-bright coal 2,semi-dull coal 3,and dull coal 4)and 2 types of coal structures(primary coal I and cataclastic coal II).Based on a range of pore testing experiments and analytical methods,the dual effects of different macrolithotypes and coal structures on pore structures were intensely studied.The results showed that the specific surface area(SSA)and total pore volume(TPV)of coal samples increased gradually from bright to dull coals.For the same macrolithotypes,the SSA and TPV of the primary coals were lower than those of the cataclastic coals.Generally,the pore structures of bright and semi-bright coals are simpler when compared to semi-dull and dull coals with the same coal structure,whereas cataclastic coals have more complicated pore structure systems than primary coals with the same macrolithotypes.The bright and semi-bright coals have higher vitrinite contents and more endogenous fractures,whereas well-developed structural fractures were identified in cataclastic coals.Therefore,bright and semi-bright coals have better pore connectivity than semi-dull and dull coals with the same coal structure,the pore connectivity of cataclastic coals being slightly better than that of primary coals under the same macrolithotypes.In terms of the CBM adsorption conditions,the eight type samples formed a descending order:Ⅱ-4>I-4>Ⅱ-3>Ⅰ-3>Ⅱ-2>Ⅰ-2>Ⅱ-1>Ⅰ-1,while they ranked as follows when consideration was given to the CBM seepage capacities:II-2>Ⅱ-1>Ⅰ-2>Ⅰ-1>Ⅰ-3>Ⅰ-4>Ⅱ-3>Ⅱ-4.As a result,it could be determined that the bright and semi-bright coals had stronger adsorption capacities,whereas the cataclastic coals had better pore connectivity and seepage capacities.Pore structure characteristics should be analysed under the dual control of different macrolithotypes and coal structures,so that they can provide greater value for guiding CBM exploration and exploitation,as along for preventing underground gas accidents.
基金granted by the Xinjiang Geological Exploration Fund。
文摘The northwestern margin of Junggar Basin is the region with the richest oil sand resources in China.For better understanding the enrichment rules and deployment of exploration and development of regional oil sand,it is of great scientific significance to study the accumulation conditions of oil sand in different strata and mining areas of the Junggar Basin.Through a large number of field investigations,drilling verification and sampling tests,it is found that the oil sand in the region covers an area of 2000 km^(2),with shallow and thick reservoir,and predicted resource of 180 million tons.The oil sand resources are mainly distributed in four geological strata,namely the Middle Triassic Karamay Formation,Early Jurassic Badaowan Formation,Late Jurassic Qigu Formation,and Early Cretaceous Qingshuihe Formation.The reservoir is mainly composed of sandstone with high porosity and permeability,and the reservoir space is mainly intergranular pores with a medium average oil content.The oil sand deposit in the region is a typical destructive oil reservoir.The crude oil in the oil sand layer is degraded and thickened from the deep to the shallow,the content of saturated hydrocarbon decreased,and the content of aromatic hydrocarbon,non-hydrocarbon and asphaltene increased.The oil source comes from the deep Permian hydrocarbon-generating depression.Unconformities,faults and marginal fan delta-braided river depositional systems constitute effective migration and storage systems.Caprocks of the Upper Triassic Baijiantan Formation,Lower Jurassic Sangonghe Formation and Lower Cretaceous Hutubihe Formation were formed by three large scale lake transgressions.The Indosinian,Yanshan and Late Yanshan movements are the main driving forces for the migration of deep oil and gas to the shallow edge to form oil sand deposits.It is considered that the oil sand in the northwestern margin of Junggar Basin is of a slope complex migration type.
基金financially supported by the National Natural Science Foundation of China(Nos.41772132,41502157,41530314)the key project of the National Science&Technology(No.2016ZX05043-001)+1 种基金the Fundamental Research Funds for the Central Universities(No.2652019095)the China Postdoctoral Science Foundation(No.2021M692998)。
文摘The composition and sedimentary controlling effect of the coal measure gas-bearing(CMG)system of the Jurassic Xishanyao Formation in the southern margin of the Junggar Basin(SJB)are analysed based on core observations,sample tests,and logging data.The results show that the lithological associations of the SJB can be classified into 6 types based on sediment supply strengths and sealing abilities,while the gas shows of CMG reservoirs vary greatly among different lithological associations.Due to the diversified coal-forming environment and multistage coal accumulation,superimposed CMG systems are generally developed in the SJB,and their types include:superimposed unattached CMG systems,multilayer unified CMG systems,and superimposed mixed CMG systems.Furthermore,sedimentary controls on the vertical and regional distributions of different types of CMG systems are discussed according to the sedimentary facies of single wells and well cross-sections and the corresponding data of well log,gas logging,and gas contents.Shore shallow lake environments in the Fukang,Miquan,and northern Liuhuanggou areas were favourable for forming superimposed unattached CMG systems.Braided river environments in the Houxia and the southern Liuhuanggou areas usually formed multilayer unified CMG systems.Braided river delta environments in the Manasi,Hutubi,and eastern Sikeshu areas generally developed multilayer unified CMG systems and superimposed mixed CMG systems.For different types of superimposed CMG systems,the number of gas-bearing units,coal seam gas content,vertical hydraulic connectivity and lateral continuity vary considerably,which makes it necessary to tailor the CMG co-production plan to the type of CMG system.
基金supported by the National Key R&D Program of China(No.2021YFC2901802)project of the China Geological Survey(No.DD20240073)Key R&D Program of Shaanxi Province(No.2024GH-ZDXM-26).
文摘1.Objective The Eastern Junggar Kalamaili region in Xinjiang constitutes a significant tin metallogenic belt in northwest China(Fig.1a).It hosts four independent tin deposits-Kamusite,Ganliangzi,Beilekuduke,and Sareshenke-from west to east,supplemented by two tin mineralized points,namely Hongtujingzi and Sujiquan(Figs.1b).according to the ore type and the composition of gangue minerals,the tin deposits in the region are classified into two groups:Quartz vein type and greisen type,with the Sareshenke deposit ascribed to the former and the remainder to the latter.
基金supported by the National Natural Science Foundation of China(Grant Nos.42172109,41872113,42172108)China National Petroleum Corporation-China University of Petroleum(Beijing)Strategic Cooperation Science and Technology Project(Grant No.ZLZX2020-02)+1 种基金State's Key Project of Research and Development Plan(Grant No.2018YFA0702405)Science Foundation of China University of Petroleum(Beijing)(Grant Nos.2462020BJRC002,2462020YXZZ020)。
文摘This study focuses on tuffaceous clastic rocks of the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin.It aims to explore the influence of sedimentation and parent rock on this kind of reservoir development.The results show that the tuffaceous components formed by the denudation of ultramafic and mafic rocks can transform into chlorite coating or hematite,while those from intermediate rock denudation can be dissolved or transformed into illite.Sedimentary facies and lithofacies are essential in controlling the evolutionary result of tuffaceous components.Matrix-supported medium conglomerate and grain-supported medium-fine conglomerate that developed in the fan delta plain,with a closed original geochemical systems,have been in the oxidizing environment for a long time.The tuffaceous matrices mainly transforms into hematite or illite.These minerals occupy the primary pores and are difficult to dissolve by felsic fluids,which inhibits the development of high-quality reservoirs.The grain-supported sandy fine conglomerate developed in the fan delta front was in the underwater reductive environment with an open original geochemical system.The tuffaceous matrices not only can transform into chlorite coating to strengthen the particle's compaction resistance,but also can be fully dissolved,which promotes the formation of high-quality reservoirs.
基金the National Science and Technology Major Project of China for their support。
文摘Research based on oil accumulation models is essential for exploring the hydrocarbon accumulation theory further.Studies on tight oil accumulation models focused on fan delta depositional systems,and in particular,systems involving source-reservoir separated type are scarce.To explore the accumulation model of tight oil in conglomerate,this study focused on the Permian-Triassic tight conglomerate oil in Mahu sag,Junggar Basin,using well drilling,well logging,seismic profiling,oil testing,and laboratory data,and analyzed the formation conditions,formation types,and distribution patterns of conglomerate reservoirs.The results show that,the conglomerate reservoirs are predominantly lithologic reservoirs and partly fault-lithologic reservoirs;there is no water evident at the edge or bottom around the reservoirs.The tight conglomerate layer in the delta plain subfacies of each fan exhibits high clay content and intense diagenesis,and the argillaceous rocks in the pro-fan delta subfacies and shallow lacustrine facies form the sealing and floor conditions.The sandy conglomerate of fan delta front subfacies is the main reservoir body.Additionally,strikeslip faulting in the Indosinian-Himalayan period formed an efficient faulting system for trans-stratal migration with Hercynian-Indosinian inverse faulting.Oil migration is driven by the overpressure caused by hydrocarbon generation from alkali lacustrine source rocks.The distribution of reservoirs is primarily controlled by the large fan bodies,namely the Zhongguai,Baijiantan,Karamay,Huangyangquan,Xiazijie,Xiayan,and Dabasong fans.Each fan body forms a group of reservoirs or oilfields,resulting in a widely distributed pattern,according to which reservoir and sealing constitute one whole body—i.e.,patterns of“one sand and one reservoir,one fan and one field.”This results in a quasi-continuous accumulation model,which includes strong oil charging,efficient faulting transportation,trans-stratal migration,and lithologic trapped accumulation.The proposed model is an important supplement to the existing model of quasi-continuous oil and gas accumulation.Overall,this study enriches unconventional oil and gas accumulation theories.
基金Supported by the Science and Technology Special Project of CNPC(2023YQX10111)Key Research and Development Special Project of Xinjiang Uygur Autonomous Region(2024B01015-3)。
文摘For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distribution of major hydrocarbon source rocks.Based on the latest 3D seismic,gravity-magnetic,and drilling data,together with the results of previous structural physical simulation and discrete element numerical simulation experiments,the spatial distribution of pre-existing paleo-structures and detachment layers in deep strata of southern Junggar Basin were systematically characterized,the structural deformation characteristics and formation mechanisms were analyzed,the distribution patterns of multiple hydrocarbon source rock suites were clarified,and hydrocarbon accumulation features in key zones were reassessed.The exploration targets in deep lower assemblages with possibility of breakthrough were expected.Key results are obtained in three aspects.First,structural deformation is controlled by two-stage paleo-structures and three detachment layers with distinct lateral variations:the Jurassic layer(moderate thickness,wide distribution),the Cretaceous layer(thickest but weak detachment),and the Paleogene layer(thin but long-distance lateral thrusting).Accordingly,a four-layer composite deformation sequence was identified,and the structural genetic model with paleo-bulge controlling zonation by segments laterally and multiple detachment layers controlling sequence vertically.Second,the Permian source rocks show a distribution pattern with narrow trough(west),multiple sags(central),and broad basin(east),which is depicted by combining high-precision gravity-magnetic data and time-frequency electromagnetic data for the first time,and the Jurassic source rocks feature thicker mudstones in the west and rich coals in the east according to the reassessment.Third,two petroleum systems and a four-layer composite hydrocarbon accumulation model are established depending on the structural deformation strength,trap effectiveness and source-trap configuration.The southern Junggar Basin is divided into three segments with ten zones,and a hierarchical exploration strategy is proposed for deep lower assemblages in this region,that is,focusing on five priority zones,expanding to three potential areas,and challenging two high-risk targets.
基金Supported by the National Natural Science Foundation of China(41802177,42272188,42303056)PetroChina Prospective and Basic Technological Project(2022DJ0507)+1 种基金Research Fund of PetroChina Basic Scientific Research and Strategic Reserve Technology(2020D-5008-04)National Natural Science of Sichuan Province(23NSFSC546)。
文摘Based on core and thin section data,the source rock samples from the Fengcheng Formation in the Mahu Sag of the Junggar Basin were analyzed in terms of zircon SIMS U-Pb geochronology,organic carbon isotopic composition,major and trace element contents,as well as petrology.Two zircon U-Pb ages of(306.0±5.2)Ma and(303.5±3.7)Ma were obtained from the first member of the Fengcheng Formation.Combined with carbon isotopic stratigraphy,it is inferred that the depositional age of the Fengcheng Formation is about 297-306 Ma,spanning the Carboniferous-Permian boundary and corresponding to the interglacial period between C4 and P1 glacial events.Multiple increases in Hg/TOC ratios and altered volcanic ash were found in the shale rocks of the Fengcheng Formation,indicating that multiple phases of volcanic activity occurred during its deposition.An interval with a high B/Ga ratio was found in the middle of the second member of the Fengcheng Formation,associated with the occurrence of evaporite minerals and reedmergnerite,indicating that the high salinity of the water mass was related to hydrothermal activity.Comprehensive analysis suggests that the warm and humid climate during the deposition of Fengcheng Formation is conducive to the growth of organic matter such as algae and bacteria in the lake,and accelerates the continental weathering,driving the input of nutrients.Volcanic activities supply a large amount of nutrients and stimulate primary productivity.The warm climate and high salinity are conducive to water stratification,leading to water anoxia that benefits organic matter preservation.The above factors interact and jointly control the enrichment of organic matter in the Fengcheng Formation of Mahu Sag.
基金Supported by the National Natural Science Foundation of China(41872113,42172109,42172108)CNPC-China University of Petroleum(Beijing)Strategic Cooperation Project(ZLZX2020-02)+1 种基金National Key R&D Program Project(2018YFA0702405)China University of Petroleum(Beijing)Research Project(2462020BJRC002,2462020YXZZ020)。
文摘Taking the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin as an example,the influences of the burial process in a foreland basin on the diagenesis and the development of high-quality reservoirs of deep and ultra-deep clastic rocks were investigated using thin section,scanning electron microscope,electron probe,stable isotopic composition and fluid inclusion data.The Qingshuihe Formation went through four burial stages of slow shallow burial,tectonic uplift,progressive deep burial and rapid deep burial successively.The stages of slow shallow burial and tectonic uplift not only can alleviate the mechanical compaction of grains,but also can maintain an open diagenetic system in the reservoirs for a long time,which promotes the dissolution of soluble components by meteoric freshwater and inhibits the precipitation of dissolution products in the reservoirs.The late rapid deep burial process contributed to the development of fluid overpressure,which effectively inhibits the destruction of primary pores by compaction and cementation.The fluid overpressure promotes the development of microfractures in the reservoir,which enhances the dissolution effect of organic acids.Based on the quantitative reconstruction of porosity evolution history,it is found that the long-term slow shallow burial and tectonic uplift processes make the greatest contribution to the development of deep-ultra-deep high-quality clastic rock reservoirs,followed by the late rapid deep burial process,and the progressive deep burial process has little contribution.
基金supported by the National Natural Science Foundation of China(Grant Nos.42172124,41702110,42330810 and U19B6003-01-01)the National Key R&D Program of China(Grant No.2023YFF0804302).
文摘The Carboniferous to Permian tectono-sedimentary evolution of the southern Junggar area brings new insights into understanding the subduction-collision processes in the northern Tianshan region.Integrating geophysics,geochemistry,and geochronology approaches,this study investigates the Carboniferous-Permian strata in the southern Junggar Basin.The results have revealed three distinct tectono-stratigraphic evolutionary stages,each marked by a distinctive volcano-sedimentary sequence.The Early Carboniferous strata suggest intense volcanic activities in the southern Junggar area.During the Late Carboniferous,the southern Junggar Basin was controlled by normal faulting in an extensional setting,receiving sedimentary inputs from the Junggar terrane.The Lower Permian,unconformably overlying the Upper Carboniferous,was shaped by an extensional regime and is comprised by volcano-clastic sequences that received detritus from the Yili-Central Tianshan block.These findings indicate that a Late Carboniferous forearc basin developed in the southern Junggar area,and it evolved into a post-collisional rift in the Early Permian.This period marked a dynamic shift from bidirectional subduction(rollback)to the detachment of the North Tianshan oceanic slab.We propose that the collision between the YiliCentral Tianshan block and the Junggar terrane,along with the closure of the North Tianshan Ocean,likely occurred in the Late Carboniferous(ca.306-303 Ma).
基金Supported by the National Natural Science Foundation of China(41802177,42272188)PetroChina Basic Technology Research and Development Project(2021DJ0206,2022DJ0507)Research Fund of PetroChina Basic Scientific Research and Strategic Reserve Technology(2020D-5008-04).
文摘Based on the organic geochemical data and the molecular and stable carbon isotopic compositions of natural gas of the Lower Permian Fengcheng Formation in the western Central Depression of Junggar Basin,combined with sedimentary environment analysis and hydrocarbon-generating simulation,the gas-generating potential of the Fengcheng source rock is evaluated,the distribution of large-scale effective source kitchen is described,the genetic types of natural gas are clarified,and four types of favorable exploration targets are selected.The results show that:(1)The Fengcheng Formation is a set of oil-prone source rocks,and the retained liquid hydrocarbon is conducive to late cracking into gas,with characteristics of high gas-generating potential and late accumulation;(2)The maximum thickness of Fengcheng source rock reaches 900 m.The source rock has entered the main gas-generating stage in Penyijingxi and Shawan sags,and the area with gas-generating intensity greater than 20×10^(8) m^(3)/km^(2) is approximately 6500 km^(2).(3)Around the western Central Depression,highly mature oil-type gas with light carbon isotope composition was identified to be derived from the Fengcheng source rocks mainly,while the rest was coal-derived gas from the Carboniferous source rock;(4)Four types of favorable exploration targets with exploration potential were developed in the western Central Depression which are structural traps neighboring to the source,stratigraphic traps neighboring to the source,shale-gas type within the source,and structural traps within the source.Great attention should be paid to these targets.
基金supported by the National Natural Science Foundation of China,(Grant No.42072144)Shengli Oilfield,SINOPEC,China(Nos.30200018-21-ZC0613-0030 and 30200018-20-ZC0613-0116)。
文摘Based on the theory of superimposed deformation and the regional tectonic background,the multi-phase non-coaxial superimposed structures in Junggar Basin were systematically analyzed using seismic interpretation,field outcrop observation,and paleo-stress field recovery methods according to the characteristics of the current tectonic framework.Moreover,the tectonic evolution process of the basin was reconstructed using sandbox analogue modelling technology.The results showed that the study area has experienced five phases of non-coaxial deformation with superimposition:The first phase of deformation(D1)is characterized by NNE-SSW extension during late Carboniferous to early Permian,which formed large graben,half graben and other extensional structure style around the basin.The second phase of deformation(D2)is represented by NE-SW compression during the middle to late Permian,and it comprised numerous contraction structures that developed based on D1.The basic form of the entire basin is alternating uplift and depression.The third phase of deformation(D3)is the NW-SE transpressional strike-slip in the Triassic-Jurassic,which produced numerous strike-slip structural styles in the middle part of the basin.The fourth phase of deformation(D4)is the uniform sedimentation during Cretaceous,and the fifth phase(D5)is the compression along NNE-SSW due to the North Tianshan northward thrust,which produced three rows of fold thrust belts and tear faults in the front of the mountain in the southern margin of the basin.The newly established three-dimensional tectonic evolution model shows that,based on the large number of NW-trending grabens and half grabens in the Carboniferous basement of Junggar Basin,multiple level NE trending uplifts have formed with the joint superposition of the late structural inversion and multiple stress fields.This has resulted in the current tectonic units of alternating uplifts and depressions in different directions in the study area.
基金financially supported by the Russian Science Foundation (RSF) (Grant No. 22-77-00082)financially supported of grant 075-15-2021-680 of the Ministry of Science and Higher Education of the Russian Federation
文摘The combined petrographic,petrological,geochemical and geochronological study of the Neoproterozoic gneisses of the Sarychabyn and Baskan complexes of the Junggar Alataw of South Kazakhstan elucidate the Precambrian tectonic evolution of the Aktau–Yili terrane.It is one of the largest Precambrian crustal blocks in the western Central Asian orogenic belt.The U-Pb single-grain zircon ages indicate that granite-gneisses formed from the same source and crystallised in the early Neoproterozoic ca.930–920 Ma.The chemical composition of gneisses corresponds to A2-type granites.The whole-rock Nd isotopic characteristics(εNd(t)=−4.9 to−1.0 and TNd(DM-2st)=1.9 to 1.7 Ga)indicate the involvement of Paleoproterozoic crustal rocks in magma generation.Early Neoproterozoic ca.930–920 Ma A-type granitoids in the Aktau–Yili terrane of South and Central Kazakhstan might reflect within-plate magmatism adjacent to the collisional belt or a local extension setting in back-arc areas of the continental arc.
基金financially supported by the National Natural Science Foundation of China(Nos.41503048,41872145)the Key Laboratory Project of Gansu Province(No.1309RTSA041)。
文摘The mudstone,gray tuffite and carbonaceous shale in the Upper Carboniferous Batamayineishan Formation(Bashan Formation)are essential source rocks for the volcanic reservoir in eastern Junggar,northwestern China.The kerogen components,vitrinite reflectance,Rock-Eval pyrolysis,lipid biomarkers and isotope compositions were measured to understand the provenance and depositional environment of Bashan Formation under the background of volcanic activities.There were 10 and 4 periods of volcanic eruptions identified in the wells CS and DZ,respectively.The source rocks developed in the late or intermittent phase of volcanic activity.The original island arcs of the Early Carboniferous evolved into the Wucaiwan sag and the Dishuiquan sag in the Bashan Formation.The Wucaiwan sag inherited the restricted,closed residual sea,which had a slightly anoxic and hypersaline environment.The Dishuiquan sag was generally an oxidizing lacustrine environment,influenced by a marine transgression that may have occurred at the end of the DZ_(Ⅲ)period during the Late Carboniferous.Although the total organic matter decreased due to the volcanic eruption,ash could cause an increase of aquatic organisms,coinciding with increases in salinity and reducibility in the Dishuiquan sag.
基金supported by the National Natural Science Foundation of China(Grant Nos.42172147 and 41972141).
文摘Overpressure is widely developed in deep petroliferous strata in the hinterland of the Junggar Basin.However,a comprehensive understanding of its origin and effect on hydrocarbon distribution and enrichment remains lacking.In this study,we employ five empirical methods and comprehensive geological analysis to identify the origin of overpressure,and uncover the effect of overpressure on hydrocarbon enrichment.The results indicate that disequilibrium compaction is not a significant factor in overpressure generation.Instead,hydrocarbon generation,pressure transfer and diagenesis are the primary causes.The empirical methods support this conclusion.There is a positive correlation between overpressure intensity and source rock thickness and maturity.Notably,widespread cross-formational migration of hydrocarbon bearing fluid occurred,with sandstone overpressure exceeding that of adjacent shale in non-source strata.Furthermore,there is a distinct transformation from smectite to illite near the top of overpressure.Hydrocarbon generation pressurization and pressure transfer significantly effect hydrocarbon enrichment.The overpressure caused by hydrocarbon generation drives hydrocarbon migration and accumulation,establishing an optimal energy configuration between reservoir and cap rock.Faults play a crucial role in hydrocarbon vertical migration and pressure relief.The overpressure in reservoirs can reduce the porosity and permeability thresholds and enhance the charging capacity of oil and gas.
基金co-funded by the National Natural Science Foundation of China (Grant Nos. 42372160, 42072172)Shandong Province Natural Science Fund for Distinguished Young Scholars (Grant No. JQ201311)the Graduate Scientific and Technological Innovation Project financially supported by Shandong University of Science and Technology (Grant No. SDKDYC190313)。
文摘The Jurassic coal-measure source rocks in the Junggar Basin have drawn considerable attention in recent years. In our hydrocarbon thermal simulation experiments of these rocks, we found that the dark mudstone evaluated as good source rock, had a much lower hydrocarbon generation capacity than the coal and carbonaceous mudstone, evaluated as poor source rock. Based on this background, we performed Fourier transform infrared spectroscopy(FTIR) and combined the results of semi-open thermal simulation experiments to explore the association between the molecular structure and hydrocarbon production capacity, with the aim of obtaining a new understanding of hydrocarbon potential of Jurassic coal-measure source rocks from the perspective of molecular structure. The results indicate that coals exhibit lower condensation of aromatic structures and higher relative abundance of aliphatic structures with a higher degree of branched chaining than mudstones and carbonaceous mudstones. Apparent aromaticity(f_a), aromatic abundance parameter I, and degree of condensation(DOC) are negatively correlated with organic matter abundance. The aliphatic structural parameter H demonstrates a substantial positive correlation with organic matter abundance. Furthermore, aliphatic relative abundance factor A is associated with the type of organic matter;the better is the type of the organic matter, the larger is the A value. The combination of the molecular structures with the thermal simulation results shows that the aliphatic hydrogen enrichment of selected carbonaceous mudstone is similar to that of coal. However, the relative abundance of the aliphatic group of it is high, and the DOC of the aromatic structure is low, making the hydrocarbon generation base stronger and easier to crack. Thus, the hydrocarbon generation capacity of carbonaceous mudstone is slightly higher than that of coal. Mudstone has low H and I values, and the DOC is high, indicating that its hydrocarbon base is low, so it has low hydrocarbon generation capacity. Therefore, the molecular structure is closely associated with the hydrocarbon potential of coal-measure source rocks. When evaluating the qualities of coal-measure source rocks, the influence of molecular structure on these rocks should be considered.
基金financially supported by the National Natural Science Foundation of China(No.41872116)National Science and Technology Major Project(No.2017ZX05001-003)+1 种基金Initial Scientific Research Foundation of Xinjiang University for Doctor(No.620321016)Research Foundation of Tianchi Outstanding Doctor(No.51052300560)。
文摘The fine-grained sedimentary rocks have numerous bedding-parallel fractures that are essential for the migration,enrichment,and efficient development of oil and gas.However,because of their variety and the complexity of the factors that affect them,their spatial prediction by the industrial community becomes challenging.Based on sample cores,thin sections,and well-logging and seismic data,this study employed a multi-scale data matching approach to quantitatively predict the development of bedding-parallel fractures and investigate their spatial distribution.Bedding-parallel fractures in the Lucaogou Formation in Jimusar Sag frequently occur along preexisting bedding planes and lithological interfaces.Unfilled bedding-parallel fractures inside or near source-rocks exhibit enhanced oil-bearing capacity.They were identified on micro-resistivity scanning images by the presence of regularly continuous black or nearly black sinusoidal curves.Overall,the developmental degree of bedding-parallel fractures was positively related to the brittle mineral and total organic carbon contents and negatively related to single reservoir interval thickness.The maintained porosity of the reservoir matrix contributed to a thorough response to factors affecting the development of bedding-parallel fractures.Here,an effective and objective method was proposed for predicting the development and distribution of bedding-parallel fractures in the fine-grained sedimentary rocks.The method was based on the matched reservoir interval density,reservoir interval density,and matched sweet spot density of bedding-parallel fractures.The prediction method integrated the significant advantages of high vertical resolution from logging curves and strong lateral continuity from seismic data.The average relative prediction error was 8%in the upper sweet spot in the Lucaogou Formation,indicating that the evaluation parameters for bedding-parallel fractures in fine-grained sedimentary rocks were reasonable and reliable and that the proposed prediction method has a stronger adaptability than the previously reported methods.The workflow based on multi-scale matching and stepwise progression can be applied in similar fine-grained sedimentary rocks,providing reliable technological support for the exploration and development of hydrocarbons.
