Organic-rich mudstones and shales,which hold significant potential for shale oil resources,characterize the first member of the Upper Cretaceous Qingshankou Formation(K_(2)qn~1)in the Sanzhao sag of the Songliao Basin...Organic-rich mudstones and shales,which hold significant potential for shale oil resources,characterize the first member of the Upper Cretaceous Qingshankou Formation(K_(2)qn~1)in the Sanzhao sag of the Songliao Basin,NE China.Focusing on 30 core samples obtained from the first shale oil parameter well,named SYY3 in the study area,we systematically analyzed the composition and stratigraphic distribution of the K_(2)qn~1 heteroatomic compounds using electrospray ionization Fourier transform-ion cyclotron resonance mass spectrometry(ESI FT-ICR MS),to assess their geological relevance to shale oil.The findings indicate that in the negative ion mode,the heteroatomic compounds predominantly consist of N_(1),N_(1)O_(1)-N_(1)O_(8),O_(1)-O_(8),O_(1)S_(1)-O_(6)S_(1);contrastingly,in the positive ion mode,they are primarily composed of N_(1)-N_(2),N_(1)O_(1)-N_(1)O_(4),N_(2)O_(1),O_(1)-O_(4),O_(1)S_(1)-O_(2)S_(1).Heteroatomic compound distributions vary significantly with depth in the negative ion mode,with minor variations in the positive ion mode.These distributions are categorized into three types based on the negative ion ratio((N_(1)+N_(1)O_(x))/O_(x)):TypeⅠ(>1.5),TypeⅡ(0.8-1.5),and TypeⅢ(<0.8);typesⅠandⅡgenerally exhibit a broader range of carbon numbers compared to TypeⅢ.The distribution of double bond equivalent(DBE)values across various sample types exhibits minimal variance,whereas that of carbon numbers shows substantial differences.Variations in heteroatomic compound compositions among the samples might have resulted from vertical sedimentary heterogeneity and differing biotic contributions.TypeⅢsamples show a decrease in total organic carbon(TOC)and free oil content(S_(1))compared to typesⅠandⅡ,but an increased oil saturation index(OSI),indicating a lower content of free oil but a higher proportion of movable oil.The reduced content of N-containing compounds implies lower paleolake productivity during deposition,leading to a reduction in TOC and S_(1).A lower TOC can enhance oil movability due to reduced oil adsorption,and the decreased presence of polar nitrogenous macromolecules with fewer highC-number heteroatomic compounds further promote shale oil movability.Additionally,the negative ion ratios of N1/N1O1and O2/O1 exhibit positive and negative correlations with the values of TOC,S_(1),and extractable organic matter(EOM),respectively,indicating that the salinity and redox conditions of the depositional water body are the primary controlling factors for both organic matter enrichment and shale oil accumulation.展开更多
Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods...Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods of the coal-bearing formations were determined,and the fault systems were divided.Combined with the coal seam thickness and actual gas indication in logging,the controls of fault systems in the rift basin on the spatial distribution of coal and the occurrence of coal-rock gas were identified.The results show that the Wangfu fault depression is an asymmetrical graben formed under the control of basement reactivated strike-slip T-rupture,and contains coal-bearing formations and five sub-types of fault systems under three types.The horizontal extension strength,vertical activity strength and tectono-sedimentary filling difference of basement faults control vertical stratigraphic sequences,accumulation intensity,and accumulation frequency of coal seam in rift basin.The structural transfer zone formed during the segmented reactivation and growth of the basement faults controls the injection location of steep slope exogenous clasts.The filling effect induced by igneous intrusion accelerates the sediment filling process in the rift lacustrine area.The structural transfer zone and igneous intrusion together determine the preferential accumulation location of coal seams in the plane.The faults reactivated at the basement and newly formed during the rifting phase serve as pathways connecting to the gas source,affecting the enrichment degree of coal-rock gas.The vertical sealing of the faults was evaluated by using shale smear factor(SSF),and the evaluation criterion was established.It is indicated that the SSF is below 1.1 in major coal areas,indicating favorable preservation conditions for coal-rock gas.Based on the influence factors such as fault activity,segmentation and sealing,the coal-rock gas accumulation model of rift basin was established.展开更多
Twelve new dinosaur teeth have recently been recovered from three localities in the Upper Cretaceous Nenjiang Formation of the Songliao Basin.Although fragmentary,the material offers enough evidence to identify the fo...Twelve new dinosaur teeth have recently been recovered from three localities in the Upper Cretaceous Nenjiang Formation of the Songliao Basin.Although fragmentary,the material offers enough evidence to identify the following taxa:tyrannosaurids,dromaeosaurines,velociraptorines,hadrosauroids,and titanosaurs.In addition to the previously known dinosaurs from the basin,several new ones have been identified,extending the paleogeographic range of related taxa.The discovery of these new fossil remains provides valuable insights into dinosaur diversity and sheds light on the terrestrial ecosystem during the Late Cretaceous in the Songliao Basin.展开更多
Taking the GY8HC well in the Gulong Sag of the Songliao Basin,NE China,as an example,this study utilized high-precision zircon U-Pb ages from volcanic ashes and AstroBayes method to estimate sedimentation rates.Throug...Taking the GY8HC well in the Gulong Sag of the Songliao Basin,NE China,as an example,this study utilized high-precision zircon U-Pb ages from volcanic ashes and AstroBayes method to estimate sedimentation rates.Through spectral analysis of high-resolution total organic carbon content(TOC),laboratory-measured free hydrocarbons(S_(1)),hydrocarbons formed during pyrolysis(S_(2)),and mineral contents,the enrichment characteristics and controlling factors of shale oil in an overmature area were investigated.The results indicate that:(1)TOC,S_(1),and S_(2)associated with shale oil enrichment exhibit a significant 173×10^(3)a obliquity amplitude modulation cycle;(2)Quartz and illite/smectite mixed-layer contents related to lithological composition show a significant 405×10^(3)a long eccentricity cycle;(3)Comparative studies with the high-maturity GY3HC well and moderate-maturity ZY1 well reveal distinct in-situ enrichment characteristics of shale oil in the overmature Qingshankou Formation,with a significant positive correlation to TOC,indicating that high TOC is a key factor for shale oil enrichment in overmature areas;(4)The sedimentary thickness of 12-13 m corresponding to the 173×10^(3)a cycle can serve as the sweet spot interval height for shale oil development in the study area,falling within the optimal fracture height range(10-15 m)generated during hydraulic fracturing of the Qingshankou shale.Orbitally forced climate changes not only controlled the sedimentary rhythms of organic carbon burial and lithological composition in the Songliao Basin but also influenced the enrichment characteristics and sweet spot distribution of Gulong shale oil.展开更多
Based on the petroleum exploration in the Cretaceous Qingshankou Formation,northern Songliao Basin,NE China,integrated with seismic,drilling and logging data,this study investigates the characteristics and genetic mec...Based on the petroleum exploration in the Cretaceous Qingshankou Formation,northern Songliao Basin,NE China,integrated with seismic,drilling and logging data,this study investigates the characteristics and genetic mechanisms of orderly distribution and the differential enrichment patterns of conventional and unconventional hydrocarbons in the formation.Key findings involve five aspects.First,the conventional and unconventional hydrocarbons coexist orderly.Laterally,conventional oil,tight oil,and shale oil form a pattern of orderly accumulation from basin margins to the center.Vertically,shale oil,tight oil,and conventional oil develop progressively upward.Second,the coupled tectonic-sedimentary processes govern sedimentary facies differentiation and diagenesis,influencing reservoir physical properties and lithology,thereby controlling the orderly distribution of conventional and unconventional hydrocarbons in space.Third,the coupling of source rock hydrocarbon generation evolution,fault sealing capacity,and reservoir densification determines the orderly coexistence pattern of conventional and unconventional hydrocarbons.Fourth,sequential variations in reservoir physical properties generate distinct dynamic fields that regulate hydrocarbon orderly accumulation.Fifth,enrichment controls are different depending on hydrocarbon types:buoyancy-driven,fault-transport,sandbody-connected,and trap-concentrated,for above-source conventional oil;overpressure-driven,fault-transport,multi-stacked sandbodies,and quasi-continuous distribution for near-source tight oil and gas;self-sourced reservoirs,retention through self-sealing,in-situ accumulation or micro-migration driven by hydrocarbon-generation overpressure for inner-source shale oil.From exploration practices,these findings will effectively guide the integrated deployment and three-dimensional exploration of conventional and unconventional hydrocarbon resources in the Qingshankou Formation,northern Songliao Basin.展开更多
The Songliao Basin in northeast China is one of the largest petroliferous basins worldwide,and features the T_(2)fault system,which consists of numerous minor extensional normal faults.This study combines high-resolut...The Songliao Basin in northeast China is one of the largest petroliferous basins worldwide,and features the T_(2)fault system,which consists of numerous minor extensional normal faults.This study combines high-resolution 3D seismic datasets to detail the characteristics of the T_(2)fault system,contributing two key findings:(1)The T_(2)faults are confirmed as polygonal fault systems,characterized by closely spaced,layer-bounded faults with small throws,high dip angles,and random orientations,forming intricate polygonal networks.(2)The study reveals the influence of tectonic stresses on the fault system,showing spatial variations across different tectonic units.In depressions,T_(2)faults exhibit short lengths,small throws,high density,and multiple directions.In contrast,in inverted anticline belts,they have longer lengths,bigger throws,higher density,and concordant orientations.These variations demonstrate the impact of tectonic inversion on the development of T_(2)faults.The significance of this research lies in presenting a typical polygonal fault system developed in a deep lake succession and was superposed the influence by regional tectonic stress coeval with its development.The new insights facilitate a reevaluation of the T_(2)fault system's role in hydrocarbon migration and accumulation within the Songliao Basin.展开更多
Taking the shale oil of the first member of the Cretaceous Qingshankou Formation of Changling Sag in southern Songliao Basin as an example,this paper establishes a saturation model of lacustrine shale oil considering ...Taking the shale oil of the first member of the Cretaceous Qingshankou Formation of Changling Sag in southern Songliao Basin as an example,this paper establishes a saturation model of lacustrine shale oil considering the influence of organic matter on clay-bound water conductivity.Based on the fluid characterization results of sealed samples and two-dimensional nuclear magnetic resonance,the differential influence of organic matter on clay-bound water conductivity was quantitatively revealed,and the conductivity mechanism and rock-electrical relationships of lacustrine shale were systematically analyzed.The results show that there are two conductive networks for lacustrine shales,i.e.the matrix free water and the clay-bound water.The bound water cementation index msh was introduced to reflect the impact of organic matter on clay-bound water conductivity,and it is positively correlated with the effective porosity.When there is sufficient rigid framework support and well-developed pores,organic matter is more likely to fill or adsorb onto clay interlayers.This reduces the ion exchange capacity of the electrical double layer,leading to an increase in msh and a decrease in the conductivity of clay-bound water.The overall conductivity of shale is controlled by the clay-bound water conductivity,and the relative contributions of the mentioned two conductive networks to formation conductivity are affected by the effective porosity and msh.The larger the effective porosity and msh,the more the contribution of the matrix free water to formation conductivity.According to the experimental results,the proposed saturation model yields a significantly higher interpretation accuracy in oil saturation than the Archie model and the Total-shale model.展开更多
High-quality reservoirs occur in the middle-shallow horizons of the northern Songliao Basin. The distribution and genesis of their anomalously high porosity zones were studied using measured porosities, examination of...High-quality reservoirs occur in the middle-shallow horizons of the northern Songliao Basin. The distribution and genesis of their anomalously high porosity zones were studied using measured porosities, examination of ordinary thin sections and blue epoxy resin-impregnated thin sections and by SEM. The results show that there are three anomalously high porosity zones at the depth of 450-900 m, 1,300-1,900 m, 2,050-2,350 m respectively, named zone i, zone ii and zone iii from top to bottom. Horizontally, zone i and zone ii are distributed all over the basin except in the Southeastern Uplift, while zone iii is only distributed in the Central Depression. Zone i was formed by meteoric water leaching as well as organic acid dissolution. Zones ii and iii were dominantly formed by organic acid dissolution. Additionally, clay mineral transformation generating H＋ and hydrocarbon emplacement retarding the cementation of sandstones are also important for the formation of zones ii and iii.展开更多
The Songliao basin （SB） is a superposed basin with two different kinds of basin fills. The lower one is characterized by a fault-bounded volcanogenic succession comprising of intercalated volcanic, pyrodastic and ep...The Songliao basin （SB） is a superposed basin with two different kinds of basin fills. The lower one is characterized by a fault-bounded volcanogenic succession comprising of intercalated volcanic, pyrodastic and epiclastic rocks. The volcanic rocks, dating from 110 Ma to 130 Ma, are of geochemically active continental margin type. Fast northward migration of the SB block occurred during the major episodes of the volcanism inferred from their paleomagnetic information. The upper one of the basin fill is dominated by non-marine sag-style sedimentary sequence of silicidastics and minor carbonates. The basin center shifted westwards from the early to late Cretaceous revealed by the GGT seismic velocity structure suggesting dynamic change in the basin evolution. Thus, a superposed basin model is proposed. Evolution of the SB involves three periods including （1） Alptian and pre- Aptian： a retroarc basin and range system of Andes type related to Mongolia-Okhotsk collisional belt （MOCB）; （2） Albian to Companian： a sag-like strike-slip basin under transtension related to oblique subduction of the Pacific plate along the eastern margin of the Eurasian plate; （3） since Maastrichtian： a tectonic inverse basin under compression related to normal subduction of the Pacific plate under the Eurasian plate, characterized by overthrust, westward migration of the depocenter and eastward uplifting of the basin margin.展开更多
Comparing compositions of the fluid inclusions in volcanic rocks to the contents and isotopes of the gases in corresponding volcanic reservoirs using microthermometry, Raman microspectroscopy and mass spectrum analysi...Comparing compositions of the fluid inclusions in volcanic rocks to the contents and isotopes of the gases in corresponding volcanic reservoirs using microthermometry, Raman microspectroscopy and mass spectrum analysis, we found that： （1） up to 82 mole% methane exists in the primary inclusions hosted in the reservoir volcanic rocks; （2） high CH4 inclusions recognized in the volcanic rocks correspond to CH4-bcaring CO2 reservoirs that are rich in helium and with a high ^3He/^4He ratio and which show reversed order of 813C in alkane; （3） in gas reservoirs of such abiotic methane （〉80%） and a mix of CH4 and CO2, the enclosed content of CH4 in the volcanic inclusions is usually below 42 mole%, and the reversed order of δ^13C in alkane is sometimes irregular in the corresponding gas pools; （4） a glassy inclusion with a homogeneous temperature over 900℃ also contains a small portion of CH4 although predominantly CO2. This affinity between gas pool and content of inclusion in the same volcanic reservoirs demonstrates that magma-originated gases, both CH4 and CO2, have contributed significantly to the corresponding gas pools and that the assumed hydrocarbon budget of the bulk earth might be much larger than conventionally supposed.展开更多
Lacustrine shale from the Qingshankou Formatin of Songliao basin and the Shahejie Formation of Bohai Bay basin, and marine shale from the lower Cambrian Jinmenchong Formation of Qiannan depression were analysed by usi...Lacustrine shale from the Qingshankou Formatin of Songliao basin and the Shahejie Formation of Bohai Bay basin, and marine shale from the lower Cambrian Jinmenchong Formation of Qiannan depression were analysed by using rock pyrolysis, TOC （total organic carbon）, XRD （X-ray diffraction）, SEM （scanning electron microscope）, FE-SEM （field emission scanning electron microscope）, high pressure mercury intrusion, and low pressure N2 and CO2 gas adsorption experiments, in aim to reveal their reservoir features. The results show that： （1） the width of micro-pores of all the studied samples mainly ranges from 0.45 to 0.7 nm indicated by CO2 isotherms, and the width of meso-pores is less than 10 nm, with type IV adsorption isotherms and type H2 hysteresis loop, indicative of ＂ink-bottle＂-shaped pores. Good correlations exist among pore volume, surface area and averaged pore diameter, and a good positive correlation exists between micro-pore volume and TOC content; however, there is no obvious correlation between meso-pore volume and TOC content; （2） interparticle pores, pores among the edge of mineral grains and organic matter pores were all identified in marine and lacustrine shale, among which the interparticle pores may be influence by dissolution effect. Not all bitumen develops organic matter pore, and only high to over mature bitumen present pores. Now the description methods of micrometer scale pores developed in shale are very lack. Micro- fractures developed in Jiyang depression and dissolution interparticle pores developed in Songliao Basin should be the accumulation sites for shale oil in lacustrine shale, and can be as sweet spots.展开更多
There are many factors affecting the chemical characteristics of groundwater in the forming process of groundwater chemical fields, such as freshening due to meteoric water leaching downwards, freshening due to mudsto...There are many factors affecting the chemical characteristics of groundwater in the forming process of groundwater chemical fields, such as freshening due to meteoric water leaching downwards, freshening due to mudstone compaction and water release, concentration due to infiltration and freshening due to dehydration of clay minerals. As a result, the groundwater chemical fields are characterized by lengthwise stages and planar selectivity. The former arouses vertical chemical zonality of groundwater. Five units could be identified downwards in the Songliao basin： （1） freshening zone due to downward-leaching meteoric water, （2） concentration zone due to evaporation near the ground surface, （3） freshening zone due to mudstone compaction and water release, and concentration zone due to compaction and infiltration, （4） freshening zone due to dehydration of clay minerals, and （5） filtration-concentration zone; whereas the latter determines the planar division of groundwater chemical fields： （1） the freshening area due to meteoric water, asymmetrically on the margin of the basin, （2） the freshening area due to mudstone compaction and water release in the central part of the basin, （3） the leaky area, which is a transitional zone, and （4） leakage-evaporation area, which is a concentration zone. In the direction of centrifugal flows caused by mudstone compaction in the depression area, the mineralization degree, concentrations of Na^＋ and Cl^-, and salinity coefficient （SC） increase, while concentrations of （CO3^2- ＋HCO3^-） and SO4^2-, metamorphism coefficient （MC） and desulfuration coefficient （DSC） decrease. However, all these parameters increase in the direction of gravity-induced centripetal flows.展开更多
The rupture of the lithosphere in Late Jurassic brought about the eruption of basaltic magma in the Songliao Basin. The evolution of the basin in Cretaceous progressed through six stages: pre-rift doming, extensional ...The rupture of the lithosphere in Late Jurassic brought about the eruption of basaltic magma in the Songliao Basin. The evolution of the basin in Cretaceous progressed through six stages: pre-rift doming, extensional fracturing, fault subsidence, fault downwarping, downwarping and shringkage, resulting in the deposition of terrstrial facies nearly 10,000 m thick. There are different depositional sequences in these stages: the depositional period of the Early Cretaceous Shahezi and Yincheng Formations is the development stage of the down-faulted basin, forming a volcanic rock-alluvial fan-fan delta-lacustrine (intercalated with episodic turbidites)-swamp facies sequences; the period of the Early Cretaceous Dengluku Formation is the transformation stage of fault subsidence into fault downwarping of the basin, forming a sequence mainly of alluvial plain-lacustrine facies; the depositional period of the Early Cretaceous Quantou Formation-Late Cretaceous Nenjiang Formation is the downwarping stage of the basin, forming an alluvial plain-delta-lacustrine facies sequence; the period of the Late Cretaceous Sifangtai Formation-Mingshui Formation is the shringkage stage of the basin, forming again a sequence mainly of alluvial plain-alluvial fan and small relict lacustrine facies. These vertical depositional sequences fully display the sedimentary characteristics of a failed continental rift basin. Many facts indicate that the two large-scale lake invasions, synchronous with the global rise of sea level, which took place in the downwarping stage of the basin development, led to the connection between the lake and sea.展开更多
Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation （K2qn^1） and Member 1 and 2 of the Nenjiang Formation （K2n^1-2） of Late Cretaceous age in the Songliao Basin reveals...Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation （K2qn^1） and Member 1 and 2 of the Nenjiang Formation （K2n^1-2） of Late Cretaceous age in the Songliao Basin reveals sedimentary cyclicities controlled by Milankovitch climate periodicities. The recognition of Milankovitch cycles allows estimation of an average accumulation rate of ～7.55- 8.62 cm/ka for the K2qn^1 sections, and ～6.69-10.16 cm/ka for the K2n^1-2 sections. Two marine transgression events occurred during the deposition of K2qn^1 and K2n^1-2 and their ages are at ～0.74- 1.10 Ma and ～2.38-4.84 Ma, respectively. Identification of Milankoviteh cycles from fine-grained deep lake sedimentary rocks in the Songliao Basin may provide great potential for high-resolution stratigraphic subdivisions and correlations.展开更多
The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen gas.The gas composition and stable isotope characteristics vary significantl...The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen gas.The gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been weak.Based on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different strata.The gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary environment.With increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to inorganic.The origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and mantle-derived.The shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic gas.Furthermore,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived gas.The discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.展开更多
The Songliao Basin in Northeast Asia is the largest and longest-lived rift basin and preserves a nearcontinuous continental succession of the most of the Cretaceous period,providing great material to investigate the a...The Songliao Basin in Northeast Asia is the largest and longest-lived rift basin and preserves a nearcontinuous continental succession of the most of the Cretaceous period,providing great material to investigate the adaption of the terrestrial systems to the Cretaceous greenhouse climate and tectonic events.However,the paucity of precise and accurate radioisotopic ages from the Early Cretaceous strata of the Songliao Basin has greatly held back the temporal and causal correlation of the continental records to the global Early Cretaceous records.Three tuff layers intercalated in the Yingcheng Formation have been intercepted by the SK-2 borehole,which offer excellent materials for radioisotopic dating and calibration of the chronostratigraphy of the Lower Cretaceous sequence of Songliao Basin.Moreover,the Yingcheng Formation recorded the largest and the last of the two major volcanic events in Songliao Basin,which also represents a turning point in the basin evolution history of Songliao from syn-rift stage to post-rift stage.Here we report high-precision U–Pb zircon geochronology by the CA-ID-TIMS technique on three tuff samples from the Yingcheng Formation of the SK-2 borehole in the Songliao Basin to construct a greatly improved,absolute age framework for the Yingcheng Formation and provide crucial age constraints for the Songliao Lower Cretaceous Strata.The new CA-ID-TIMS geochronology constrained the Yingcheng Formation at 102.571+0.320/-2.346 Ma to ca.113 Ma,correlating to the Albian Stage.Combined with the previous published Songliao geochronology,the Quantou Formation is constrained to between 96.442+0.475/-0.086 Ma and 91.923+0.475/-0.086 Ma;the Denglouku Formation is constrained to between 102.571+0.320/-2.346 Ma and 96.442+0.475/-0.086 Ma;the age of the Shahezi Formation is estimated at ca.113 Ma to ca.118 Ma,which could extend to ca.125 Ma in some locations in Songliao Basin.The major unconformity between the Yingcheng Formation and the Denglouku Formation,which represents the transition of the basin from syn-rift to post-rift is thus confined to between 102.571+0.320/-2.346 Ma and 96.442+0.475/-0.086 Ma.This is roughly contemporaneous with the change in the direction of the paleo-Pacific plate motion from west-southwest to north or northwest in mid-Cretaceous,suggesting their possible connections.展开更多
The resource of the gas from coal and coal measures deep in Songliao Basin has been drawing more and more attention to . It is necessary to find out the evolution regularity of the geothermal field of the basin in add...The resource of the gas from coal and coal measures deep in Songliao Basin has been drawing more and more attention to . It is necessary to find out the evolution regularity of the geothermal field of the basin in addition to a series of geological studies in order to predict its resources because the ancient geothermal field of the basin is one of the main factors controlling the generation , evolution and disappearance of oil and gas . In the recent twenty years , it is generally believed that vitrinite reflectance is the best quantitative marker for the ancient geothermal field . In the present paper , a systematic study of the vitrinite reflectance value of Songliao Basin and its influence factors is made by multiple statistical analysis so as to reconstruct the evolutional process of the Moho and the corresponding geothermal field . Then , an overall prediction is made of the vitrinite reflectance and the distribution of J3-K1 fault basin group at the bottom of Songliao Basin , which provides the evidence for the further prediction of the gas potentiality from coal and coal measures deep in the basin .展开更多
Based on the abundant information from drilling, cores, and logging, the influence of topography, size of rivers and lakes, climate changes and the lake level＇s fluctuation on the sandbodies at shallow-water delta fr...Based on the abundant information from drilling, cores, and logging, the influence of topography, size of rivers and lakes, climate changes and the lake level＇s fluctuation on the sandbodies at shallow-water delta front are systematically summarized and the sedimentary dynamic processes are analyzed. The interwell communication among the sandbodies and their planar distribution revealed from the hydrodynamic features of the development wells are integrated during the analysis. The fundamental requirements for the development of the shallow-water delta included flat topography and uniform subsiding rate. The delta plain was connected smoothly with the wide delta front and predelta, without the three-fold structure of topset, foreset, and bottomset as defined in the Gilbert Delta Model. Because of the weak fluvial effect and the lake energy is strong, the small and scattered shallow-water delta is destroyed by the scouring-backwashing, coastal current, and lake wave, resulting in the coastal sheet deposition. As the fluvial effect became stronger and the lake energy became weaker, the shape of the shallow-water deltas transferred from sheets to lumps and then branches.展开更多
Through the study of organic matter enrichment,hydrocarbon generation and accumulation process of black shale of the Cretaceous Qingshankou Formation in the Songliao Basin,the enrichment mechanism of Gulong shale oil ...Through the study of organic matter enrichment,hydrocarbon generation and accumulation process of black shale of the Cretaceous Qingshankou Formation in the Songliao Basin,the enrichment mechanism of Gulong shale oil and the distribution of conventional–unconventional oil are revealed.The Songliao Basin is a huge interior lake basin formed in the Early Cretaceous under the control of the subduction and retreat of the western Pacific plate and the massive horizontal displacement of the Tanlu Fault Zone in Northeast China.During the deposition of the Qingshankou Formation,strong terrestrial hydrological cycle led to the lake level rise of the ancient Songliao Basin and the input of a large amount of nutrients,resulting in planktonic bacteria and algae flourish.Intermittent seawater intrusion events promoted the formation of salinization stratification and anoxic environment in the lake,which were beneficial to the enrichment of organic matters.Biomarkers analysis confirms that the biogenic organic matter of planktonic bacteria and algae modified by microorganisms plays an important role in the formation of high-quality source rocks with high oil generation capability.There are four favorable conditions for the enrichment of light shale oil in the Qingshankou Formation of the Gulong Sag,Songliao Basin:the moderate organic matter abundance and high oil potential provide sufficient material basis for oil enrichment;high degree of thermal evolution makes shale oil have high GOR and good mobility;low hydrocarbon expulsion efficiency leads to a high content of retained hydrocarbons in the source rock;and the confinement effect of intra-layer cement in the high maturity stage induces the efficient accumulation of light shale oil.The restoration of hydrocarbon accumulation process suggests that liquid hydrocarbons generated in the early(low–medium maturity)stage of the Qingshankou Formation source rocks accumulated in placanticline and slope after long-distance secondary migration,forming high-quality conventional and tight oil reservoirs.Light oil generated in the late(medium–high maturity)stage accumulated in situ,forming about 15 billion tons of Gulong shale oil resources,which finally enabled the orderly distribution of conventional–unconventional oils that are contiguous horizontally and superposed vertically within the basin,showing a complete pattern of“whole petroleum system”with conventional oil,tight oil and shale oil in sequence.展开更多
The pollen and spores found in the Early Cretaceous strata of two cores from the Shuangliao Fault Depression were studied systematically, and two palynological assemblages have been recognized. Assemblage I from the Y...The pollen and spores found in the Early Cretaceous strata of two cores from the Shuangliao Fault Depression were studied systematically, and two palynological assemblages have been recognized. Assemblage I from the Yingcheng Formation is named Paleoconiferus-Pinuspollenites; the assemblage is characterized by an extremely high content of Paleoconifer pollen. Assemblage II from Member 1 of the Denglouku Formation is named Cicatricosisporites-Cyathidites-Pinuspollenites; the assemblage is characterized by the abundant presence of Laevigati spores, but less Paleoconifer pollen. According to the palynological data and zircon U-Pb dating, the geological age of the Yingcheng Formation is thought to be Aptian-Albian, and that of the Denglouku Formation is thought to be Early Albian. On the basis of the composition of each assemblage, we can infer that during the depositional period of the Yingcheng Formation, the paleovegetation was mainly conifer forest, the paleoclimate was consistent with the temperate climate of today, and the paleoenvironment was humid feature. During the depositional period of Member 1 of the Denglouku Formation, the paleovegetation was mainly conifer forest and shrubs, the paleoclimate was consistent with the subtropical climate of today, and the paleoenvironment was humid. The results significantly improve our understanding of the stratigraphy in the Shuangliao Fault Depression, provide biostratigraphic evidence for the division and correlation of Early Cretaceous strata in the Shuangliao Fault Depression, and provide new data for analyzing paleovegetation and paleoclimate in the Songliao Basin.展开更多
基金jointly funded by the National Natural Science Foundation of China(Grant Nos.42072178 and U2244207)the funding project of Northeast Geological S&T Innovation Center of China Geological Survey(Grant No.QCJJ2022-37)Geological Survey Project of China Geological Survey(Grant Nos.DD20190114,DD20230022,and DD20240045)。
文摘Organic-rich mudstones and shales,which hold significant potential for shale oil resources,characterize the first member of the Upper Cretaceous Qingshankou Formation(K_(2)qn~1)in the Sanzhao sag of the Songliao Basin,NE China.Focusing on 30 core samples obtained from the first shale oil parameter well,named SYY3 in the study area,we systematically analyzed the composition and stratigraphic distribution of the K_(2)qn~1 heteroatomic compounds using electrospray ionization Fourier transform-ion cyclotron resonance mass spectrometry(ESI FT-ICR MS),to assess their geological relevance to shale oil.The findings indicate that in the negative ion mode,the heteroatomic compounds predominantly consist of N_(1),N_(1)O_(1)-N_(1)O_(8),O_(1)-O_(8),O_(1)S_(1)-O_(6)S_(1);contrastingly,in the positive ion mode,they are primarily composed of N_(1)-N_(2),N_(1)O_(1)-N_(1)O_(4),N_(2)O_(1),O_(1)-O_(4),O_(1)S_(1)-O_(2)S_(1).Heteroatomic compound distributions vary significantly with depth in the negative ion mode,with minor variations in the positive ion mode.These distributions are categorized into three types based on the negative ion ratio((N_(1)+N_(1)O_(x))/O_(x)):TypeⅠ(>1.5),TypeⅡ(0.8-1.5),and TypeⅢ(<0.8);typesⅠandⅡgenerally exhibit a broader range of carbon numbers compared to TypeⅢ.The distribution of double bond equivalent(DBE)values across various sample types exhibits minimal variance,whereas that of carbon numbers shows substantial differences.Variations in heteroatomic compound compositions among the samples might have resulted from vertical sedimentary heterogeneity and differing biotic contributions.TypeⅢsamples show a decrease in total organic carbon(TOC)and free oil content(S_(1))compared to typesⅠandⅡ,but an increased oil saturation index(OSI),indicating a lower content of free oil but a higher proportion of movable oil.The reduced content of N-containing compounds implies lower paleolake productivity during deposition,leading to a reduction in TOC and S_(1).A lower TOC can enhance oil movability due to reduced oil adsorption,and the decreased presence of polar nitrogenous macromolecules with fewer highC-number heteroatomic compounds further promote shale oil movability.Additionally,the negative ion ratios of N1/N1O1and O2/O1 exhibit positive and negative correlations with the values of TOC,S_(1),and extractable organic matter(EOM),respectively,indicating that the salinity and redox conditions of the depositional water body are the primary controlling factors for both organic matter enrichment and shale oil accumulation.
基金Supported by the National Natural Science Foundation of China(42472190)Chongqing Natural Science Foundation Innovation and Development Joint Fund Project(CSTB2022NSCQ-LZX0020)Chongqing Talent Innovation and Entrepreneurship Leading Talent Project(0255-19230101042)。
文摘Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods of the coal-bearing formations were determined,and the fault systems were divided.Combined with the coal seam thickness and actual gas indication in logging,the controls of fault systems in the rift basin on the spatial distribution of coal and the occurrence of coal-rock gas were identified.The results show that the Wangfu fault depression is an asymmetrical graben formed under the control of basement reactivated strike-slip T-rupture,and contains coal-bearing formations and five sub-types of fault systems under three types.The horizontal extension strength,vertical activity strength and tectono-sedimentary filling difference of basement faults control vertical stratigraphic sequences,accumulation intensity,and accumulation frequency of coal seam in rift basin.The structural transfer zone formed during the segmented reactivation and growth of the basement faults controls the injection location of steep slope exogenous clasts.The filling effect induced by igneous intrusion accelerates the sediment filling process in the rift lacustrine area.The structural transfer zone and igneous intrusion together determine the preferential accumulation location of coal seams in the plane.The faults reactivated at the basement and newly formed during the rifting phase serve as pathways connecting to the gas source,affecting the enrichment degree of coal-rock gas.The vertical sealing of the faults was evaluated by using shale smear factor(SSF),and the evaluation criterion was established.It is indicated that the SSF is below 1.1 in major coal areas,indicating favorable preservation conditions for coal-rock gas.Based on the influence factors such as fault activity,segmentation and sealing,the coal-rock gas accumulation model of rift basin was established.
基金supported financially by China Geological Survey(Grant No.DD20230221)the Key Laboratory of Stratigraphy and Palaeontology,Ministry of Natural Resources(Grant No.KLSP SP202301)National Nature Science Foundation of China(Grant No.41202012).
文摘Twelve new dinosaur teeth have recently been recovered from three localities in the Upper Cretaceous Nenjiang Formation of the Songliao Basin.Although fragmentary,the material offers enough evidence to identify the following taxa:tyrannosaurids,dromaeosaurines,velociraptorines,hadrosauroids,and titanosaurs.In addition to the previously known dinosaurs from the basin,several new ones have been identified,extending the paleogeographic range of related taxa.The discovery of these new fossil remains provides valuable insights into dinosaur diversity and sheds light on the terrestrial ecosystem during the Late Cretaceous in the Songliao Basin.
基金Supported by the National Natural Science Foundation of China(42372162,4244205C)Project of"Solving Problems by Listing Talents"in Heilongjiang Province(2022-JS-1740,2022-JS-1853)Project on the Theory of Oil and Gas Enrichment from the Interaction of Earth's Multiple Spheres(THEMSIE04010103).
文摘Taking the GY8HC well in the Gulong Sag of the Songliao Basin,NE China,as an example,this study utilized high-precision zircon U-Pb ages from volcanic ashes and AstroBayes method to estimate sedimentation rates.Through spectral analysis of high-resolution total organic carbon content(TOC),laboratory-measured free hydrocarbons(S_(1)),hydrocarbons formed during pyrolysis(S_(2)),and mineral contents,the enrichment characteristics and controlling factors of shale oil in an overmature area were investigated.The results indicate that:(1)TOC,S_(1),and S_(2)associated with shale oil enrichment exhibit a significant 173×10^(3)a obliquity amplitude modulation cycle;(2)Quartz and illite/smectite mixed-layer contents related to lithological composition show a significant 405×10^(3)a long eccentricity cycle;(3)Comparative studies with the high-maturity GY3HC well and moderate-maturity ZY1 well reveal distinct in-situ enrichment characteristics of shale oil in the overmature Qingshankou Formation,with a significant positive correlation to TOC,indicating that high TOC is a key factor for shale oil enrichment in overmature areas;(4)The sedimentary thickness of 12-13 m corresponding to the 173×10^(3)a cycle can serve as the sweet spot interval height for shale oil development in the study area,falling within the optimal fracture height range(10-15 m)generated during hydraulic fracturing of the Qingshankou shale.Orbitally forced climate changes not only controlled the sedimentary rhythms of organic carbon burial and lithological composition in the Songliao Basin but also influenced the enrichment characteristics and sweet spot distribution of Gulong shale oil.
基金Supported by the PetroChina Science and Technology Major Project(2023ZZ15).
文摘Based on the petroleum exploration in the Cretaceous Qingshankou Formation,northern Songliao Basin,NE China,integrated with seismic,drilling and logging data,this study investigates the characteristics and genetic mechanisms of orderly distribution and the differential enrichment patterns of conventional and unconventional hydrocarbons in the formation.Key findings involve five aspects.First,the conventional and unconventional hydrocarbons coexist orderly.Laterally,conventional oil,tight oil,and shale oil form a pattern of orderly accumulation from basin margins to the center.Vertically,shale oil,tight oil,and conventional oil develop progressively upward.Second,the coupled tectonic-sedimentary processes govern sedimentary facies differentiation and diagenesis,influencing reservoir physical properties and lithology,thereby controlling the orderly distribution of conventional and unconventional hydrocarbons in space.Third,the coupling of source rock hydrocarbon generation evolution,fault sealing capacity,and reservoir densification determines the orderly coexistence pattern of conventional and unconventional hydrocarbons.Fourth,sequential variations in reservoir physical properties generate distinct dynamic fields that regulate hydrocarbon orderly accumulation.Fifth,enrichment controls are different depending on hydrocarbon types:buoyancy-driven,fault-transport,sandbody-connected,and trap-concentrated,for above-source conventional oil;overpressure-driven,fault-transport,multi-stacked sandbodies,and quasi-continuous distribution for near-source tight oil and gas;self-sourced reservoirs,retention through self-sealing,in-situ accumulation or micro-migration driven by hydrocarbon-generation overpressure for inner-source shale oil.From exploration practices,these findings will effectively guide the integrated deployment and three-dimensional exploration of conventional and unconventional hydrocarbon resources in the Qingshankou Formation,northern Songliao Basin.
基金supported by the Open Funds for Hubei Key Laboratory of Marine Geological Resources,China University of Geosciences(No.MGR202303)the National Natural Science Foundation of China(No.41672110)。
文摘The Songliao Basin in northeast China is one of the largest petroliferous basins worldwide,and features the T_(2)fault system,which consists of numerous minor extensional normal faults.This study combines high-resolution 3D seismic datasets to detail the characteristics of the T_(2)fault system,contributing two key findings:(1)The T_(2)faults are confirmed as polygonal fault systems,characterized by closely spaced,layer-bounded faults with small throws,high dip angles,and random orientations,forming intricate polygonal networks.(2)The study reveals the influence of tectonic stresses on the fault system,showing spatial variations across different tectonic units.In depressions,T_(2)faults exhibit short lengths,small throws,high density,and multiple directions.In contrast,in inverted anticline belts,they have longer lengths,bigger throws,higher density,and concordant orientations.These variations demonstrate the impact of tectonic inversion on the development of T_(2)faults.The significance of this research lies in presenting a typical polygonal fault system developed in a deep lake succession and was superposed the influence by regional tectonic stress coeval with its development.The new insights facilitate a reevaluation of the T_(2)fault system's role in hydrocarbon migration and accumulation within the Songliao Basin.
基金Supported by National Natural Science Foundation of China(42472217).
文摘Taking the shale oil of the first member of the Cretaceous Qingshankou Formation of Changling Sag in southern Songliao Basin as an example,this paper establishes a saturation model of lacustrine shale oil considering the influence of organic matter on clay-bound water conductivity.Based on the fluid characterization results of sealed samples and two-dimensional nuclear magnetic resonance,the differential influence of organic matter on clay-bound water conductivity was quantitatively revealed,and the conductivity mechanism and rock-electrical relationships of lacustrine shale were systematically analyzed.The results show that there are two conductive networks for lacustrine shales,i.e.the matrix free water and the clay-bound water.The bound water cementation index msh was introduced to reflect the impact of organic matter on clay-bound water conductivity,and it is positively correlated with the effective porosity.When there is sufficient rigid framework support and well-developed pores,organic matter is more likely to fill or adsorb onto clay interlayers.This reduces the ion exchange capacity of the electrical double layer,leading to an increase in msh and a decrease in the conductivity of clay-bound water.The overall conductivity of shale is controlled by the clay-bound water conductivity,and the relative contributions of the mentioned two conductive networks to formation conductivity are affected by the effective porosity and msh.The larger the effective porosity and msh,the more the contribution of the matrix free water to formation conductivity.According to the experimental results,the proposed saturation model yields a significantly higher interpretation accuracy in oil saturation than the Archie model and the Total-shale model.
基金supported by the National Natural ScienceFoundation (Grant No. 40872076)
文摘High-quality reservoirs occur in the middle-shallow horizons of the northern Songliao Basin. The distribution and genesis of their anomalously high porosity zones were studied using measured porosities, examination of ordinary thin sections and blue epoxy resin-impregnated thin sections and by SEM. The results show that there are three anomalously high porosity zones at the depth of 450-900 m, 1,300-1,900 m, 2,050-2,350 m respectively, named zone i, zone ii and zone iii from top to bottom. Horizontally, zone i and zone ii are distributed all over the basin except in the Southeastern Uplift, while zone iii is only distributed in the Central Depression. Zone i was formed by meteoric water leaching as well as organic acid dissolution. Zones ii and iii were dominantly formed by organic acid dissolution. Additionally, clay mineral transformation generating H＋ and hydrocarbon emplacement retarding the cementation of sandstones are also important for the formation of zones ii and iii.
文摘The Songliao basin （SB） is a superposed basin with two different kinds of basin fills. The lower one is characterized by a fault-bounded volcanogenic succession comprising of intercalated volcanic, pyrodastic and epiclastic rocks. The volcanic rocks, dating from 110 Ma to 130 Ma, are of geochemically active continental margin type. Fast northward migration of the SB block occurred during the major episodes of the volcanism inferred from their paleomagnetic information. The upper one of the basin fill is dominated by non-marine sag-style sedimentary sequence of silicidastics and minor carbonates. The basin center shifted westwards from the early to late Cretaceous revealed by the GGT seismic velocity structure suggesting dynamic change in the basin evolution. Thus, a superposed basin model is proposed. Evolution of the SB involves three periods including （1） Alptian and pre- Aptian： a retroarc basin and range system of Andes type related to Mongolia-Okhotsk collisional belt （MOCB）; （2） Albian to Companian： a sag-like strike-slip basin under transtension related to oblique subduction of the Pacific plate along the eastern margin of the Eurasian plate; （3） since Maastrichtian： a tectonic inverse basin under compression related to normal subduction of the Pacific plate under the Eurasian plate, characterized by overthrust, westward migration of the depocenter and eastward uplifting of the basin margin.
文摘Comparing compositions of the fluid inclusions in volcanic rocks to the contents and isotopes of the gases in corresponding volcanic reservoirs using microthermometry, Raman microspectroscopy and mass spectrum analysis, we found that： （1） up to 82 mole% methane exists in the primary inclusions hosted in the reservoir volcanic rocks; （2） high CH4 inclusions recognized in the volcanic rocks correspond to CH4-bcaring CO2 reservoirs that are rich in helium and with a high ^3He/^4He ratio and which show reversed order of 813C in alkane; （3） in gas reservoirs of such abiotic methane （〉80%） and a mix of CH4 and CO2, the enclosed content of CH4 in the volcanic inclusions is usually below 42 mole%, and the reversed order of δ^13C in alkane is sometimes irregular in the corresponding gas pools; （4） a glassy inclusion with a homogeneous temperature over 900℃ also contains a small portion of CH4 although predominantly CO2. This affinity between gas pool and content of inclusion in the same volcanic reservoirs demonstrates that magma-originated gases, both CH4 and CO2, have contributed significantly to the corresponding gas pools and that the assumed hydrocarbon budget of the bulk earth might be much larger than conventionally supposed.
基金jointly supported by grants from the Natural Science Foundation of China(grants No.41402110 and 41330313)“Fundamental Research Funds for the Central Universities”(grants No.14CX05017A and 13CX05013A)
文摘Lacustrine shale from the Qingshankou Formatin of Songliao basin and the Shahejie Formation of Bohai Bay basin, and marine shale from the lower Cambrian Jinmenchong Formation of Qiannan depression were analysed by using rock pyrolysis, TOC （total organic carbon）, XRD （X-ray diffraction）, SEM （scanning electron microscope）, FE-SEM （field emission scanning electron microscope）, high pressure mercury intrusion, and low pressure N2 and CO2 gas adsorption experiments, in aim to reveal their reservoir features. The results show that： （1） the width of micro-pores of all the studied samples mainly ranges from 0.45 to 0.7 nm indicated by CO2 isotherms, and the width of meso-pores is less than 10 nm, with type IV adsorption isotherms and type H2 hysteresis loop, indicative of ＂ink-bottle＂-shaped pores. Good correlations exist among pore volume, surface area and averaged pore diameter, and a good positive correlation exists between micro-pore volume and TOC content; however, there is no obvious correlation between meso-pore volume and TOC content; （2） interparticle pores, pores among the edge of mineral grains and organic matter pores were all identified in marine and lacustrine shale, among which the interparticle pores may be influence by dissolution effect. Not all bitumen develops organic matter pore, and only high to over mature bitumen present pores. Now the description methods of micrometer scale pores developed in shale are very lack. Micro- fractures developed in Jiyang depression and dissolution interparticle pores developed in Songliao Basin should be the accumulation sites for shale oil in lacustrine shale, and can be as sweet spots.
基金supported by the National Important Basic Research and Development Program(973)(Grant No.2001CB209104).
文摘There are many factors affecting the chemical characteristics of groundwater in the forming process of groundwater chemical fields, such as freshening due to meteoric water leaching downwards, freshening due to mudstone compaction and water release, concentration due to infiltration and freshening due to dehydration of clay minerals. As a result, the groundwater chemical fields are characterized by lengthwise stages and planar selectivity. The former arouses vertical chemical zonality of groundwater. Five units could be identified downwards in the Songliao basin： （1） freshening zone due to downward-leaching meteoric water, （2） concentration zone due to evaporation near the ground surface, （3） freshening zone due to mudstone compaction and water release, and concentration zone due to compaction and infiltration, （4） freshening zone due to dehydration of clay minerals, and （5） filtration-concentration zone; whereas the latter determines the planar division of groundwater chemical fields： （1） the freshening area due to meteoric water, asymmetrically on the margin of the basin, （2） the freshening area due to mudstone compaction and water release in the central part of the basin, （3） the leaky area, which is a transitional zone, and （4） leakage-evaporation area, which is a concentration zone. In the direction of centrifugal flows caused by mudstone compaction in the depression area, the mineralization degree, concentrations of Na^＋ and Cl^-, and salinity coefficient （SC） increase, while concentrations of （CO3^2- ＋HCO3^-） and SO4^2-, metamorphism coefficient （MC） and desulfuration coefficient （DSC） decrease. However, all these parameters increase in the direction of gravity-induced centripetal flows.
文摘The rupture of the lithosphere in Late Jurassic brought about the eruption of basaltic magma in the Songliao Basin. The evolution of the basin in Cretaceous progressed through six stages: pre-rift doming, extensional fracturing, fault subsidence, fault downwarping, downwarping and shringkage, resulting in the deposition of terrstrial facies nearly 10,000 m thick. There are different depositional sequences in these stages: the depositional period of the Early Cretaceous Shahezi and Yincheng Formations is the development stage of the down-faulted basin, forming a volcanic rock-alluvial fan-fan delta-lacustrine (intercalated with episodic turbidites)-swamp facies sequences; the period of the Early Cretaceous Dengluku Formation is the transformation stage of fault subsidence into fault downwarping of the basin, forming a sequence mainly of alluvial plain-lacustrine facies; the depositional period of the Early Cretaceous Quantou Formation-Late Cretaceous Nenjiang Formation is the downwarping stage of the basin, forming an alluvial plain-delta-lacustrine facies sequence; the period of the Late Cretaceous Sifangtai Formation-Mingshui Formation is the shringkage stage of the basin, forming again a sequence mainly of alluvial plain-alluvial fan and small relict lacustrine facies. These vertical depositional sequences fully display the sedimentary characteristics of a failed continental rift basin. Many facts indicate that the two large-scale lake invasions, synchronous with the global rise of sea level, which took place in the downwarping stage of the basin development, led to the connection between the lake and sea.
文摘Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation （K2qn^1） and Member 1 and 2 of the Nenjiang Formation （K2n^1-2） of Late Cretaceous age in the Songliao Basin reveals sedimentary cyclicities controlled by Milankovitch climate periodicities. The recognition of Milankovitch cycles allows estimation of an average accumulation rate of ～7.55- 8.62 cm/ka for the K2qn^1 sections, and ～6.69-10.16 cm/ka for the K2n^1-2 sections. Two marine transgression events occurred during the deposition of K2qn^1 and K2n^1-2 and their ages are at ～0.74- 1.10 Ma and ～2.38-4.84 Ma, respectively. Identification of Milankoviteh cycles from fine-grained deep lake sedimentary rocks in the Songliao Basin may provide great potential for high-resolution stratigraphic subdivisions and correlations.
基金supported by the National Natural Science Foundation of China(Grant No.42072168)the National Key R&D Program of China(Grant No.2019YFC0605405)the Fundamental Research Funds for the Central Universities(Grant No.2023ZKPYDC07)。
文摘The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen gas.The gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been weak.Based on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different strata.The gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary environment.With increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to inorganic.The origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and mantle-derived.The shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic gas.Furthermore,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived gas.The discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.
基金financially supported by the National Key Research and Development Project(2019YFC0605403)National Natural Science Foundation of China grants(Nos.41790451,41688103,42172117,41702109 and 41972096)。
文摘The Songliao Basin in Northeast Asia is the largest and longest-lived rift basin and preserves a nearcontinuous continental succession of the most of the Cretaceous period,providing great material to investigate the adaption of the terrestrial systems to the Cretaceous greenhouse climate and tectonic events.However,the paucity of precise and accurate radioisotopic ages from the Early Cretaceous strata of the Songliao Basin has greatly held back the temporal and causal correlation of the continental records to the global Early Cretaceous records.Three tuff layers intercalated in the Yingcheng Formation have been intercepted by the SK-2 borehole,which offer excellent materials for radioisotopic dating and calibration of the chronostratigraphy of the Lower Cretaceous sequence of Songliao Basin.Moreover,the Yingcheng Formation recorded the largest and the last of the two major volcanic events in Songliao Basin,which also represents a turning point in the basin evolution history of Songliao from syn-rift stage to post-rift stage.Here we report high-precision U–Pb zircon geochronology by the CA-ID-TIMS technique on three tuff samples from the Yingcheng Formation of the SK-2 borehole in the Songliao Basin to construct a greatly improved,absolute age framework for the Yingcheng Formation and provide crucial age constraints for the Songliao Lower Cretaceous Strata.The new CA-ID-TIMS geochronology constrained the Yingcheng Formation at 102.571+0.320/-2.346 Ma to ca.113 Ma,correlating to the Albian Stage.Combined with the previous published Songliao geochronology,the Quantou Formation is constrained to between 96.442+0.475/-0.086 Ma and 91.923+0.475/-0.086 Ma;the Denglouku Formation is constrained to between 102.571+0.320/-2.346 Ma and 96.442+0.475/-0.086 Ma;the age of the Shahezi Formation is estimated at ca.113 Ma to ca.118 Ma,which could extend to ca.125 Ma in some locations in Songliao Basin.The major unconformity between the Yingcheng Formation and the Denglouku Formation,which represents the transition of the basin from syn-rift to post-rift is thus confined to between 102.571+0.320/-2.346 Ma and 96.442+0.475/-0.086 Ma.This is roughly contemporaneous with the change in the direction of the paleo-Pacific plate motion from west-southwest to north or northwest in mid-Cretaceous,suggesting their possible connections.
文摘The resource of the gas from coal and coal measures deep in Songliao Basin has been drawing more and more attention to . It is necessary to find out the evolution regularity of the geothermal field of the basin in addition to a series of geological studies in order to predict its resources because the ancient geothermal field of the basin is one of the main factors controlling the generation , evolution and disappearance of oil and gas . In the recent twenty years , it is generally believed that vitrinite reflectance is the best quantitative marker for the ancient geothermal field . In the present paper , a systematic study of the vitrinite reflectance value of Songliao Basin and its influence factors is made by multiple statistical analysis so as to reconstruct the evolutional process of the Moho and the corresponding geothermal field . Then , an overall prediction is made of the vitrinite reflectance and the distribution of J3-K1 fault basin group at the bottom of Songliao Basin , which provides the evidence for the further prediction of the gas potentiality from coal and coal measures deep in the basin .
文摘Based on the abundant information from drilling, cores, and logging, the influence of topography, size of rivers and lakes, climate changes and the lake level＇s fluctuation on the sandbodies at shallow-water delta front are systematically summarized and the sedimentary dynamic processes are analyzed. The interwell communication among the sandbodies and their planar distribution revealed from the hydrodynamic features of the development wells are integrated during the analysis. The fundamental requirements for the development of the shallow-water delta included flat topography and uniform subsiding rate. The delta plain was connected smoothly with the wide delta front and predelta, without the three-fold structure of topset, foreset, and bottomset as defined in the Gilbert Delta Model. Because of the weak fluvial effect and the lake energy is strong, the small and scattered shallow-water delta is destroyed by the scouring-backwashing, coastal current, and lake wave, resulting in the coastal sheet deposition. As the fluvial effect became stronger and the lake energy became weaker, the shape of the shallow-water deltas transferred from sheets to lumps and then branches.
基金Supported by the Heilongjiang Province S&D Project(2022-JS-1740,2022-JS-1853)China National Petroleum Corporation Scientific Research and Technological Development Project(2021DJ1808).
文摘Through the study of organic matter enrichment,hydrocarbon generation and accumulation process of black shale of the Cretaceous Qingshankou Formation in the Songliao Basin,the enrichment mechanism of Gulong shale oil and the distribution of conventional–unconventional oil are revealed.The Songliao Basin is a huge interior lake basin formed in the Early Cretaceous under the control of the subduction and retreat of the western Pacific plate and the massive horizontal displacement of the Tanlu Fault Zone in Northeast China.During the deposition of the Qingshankou Formation,strong terrestrial hydrological cycle led to the lake level rise of the ancient Songliao Basin and the input of a large amount of nutrients,resulting in planktonic bacteria and algae flourish.Intermittent seawater intrusion events promoted the formation of salinization stratification and anoxic environment in the lake,which were beneficial to the enrichment of organic matters.Biomarkers analysis confirms that the biogenic organic matter of planktonic bacteria and algae modified by microorganisms plays an important role in the formation of high-quality source rocks with high oil generation capability.There are four favorable conditions for the enrichment of light shale oil in the Qingshankou Formation of the Gulong Sag,Songliao Basin:the moderate organic matter abundance and high oil potential provide sufficient material basis for oil enrichment;high degree of thermal evolution makes shale oil have high GOR and good mobility;low hydrocarbon expulsion efficiency leads to a high content of retained hydrocarbons in the source rock;and the confinement effect of intra-layer cement in the high maturity stage induces the efficient accumulation of light shale oil.The restoration of hydrocarbon accumulation process suggests that liquid hydrocarbons generated in the early(low–medium maturity)stage of the Qingshankou Formation source rocks accumulated in placanticline and slope after long-distance secondary migration,forming high-quality conventional and tight oil reservoirs.Light oil generated in the late(medium–high maturity)stage accumulated in situ,forming about 15 billion tons of Gulong shale oil resources,which finally enabled the orderly distribution of conventional–unconventional oils that are contiguous horizontally and superposed vertically within the basin,showing a complete pattern of“whole petroleum system”with conventional oil,tight oil and shale oil in sequence.
基金supported by the Exploration and Development Research Institute of the Jilin Oilfield Company Ltd. (Grant No.JLYT-YJY-2013-JS-305)
文摘The pollen and spores found in the Early Cretaceous strata of two cores from the Shuangliao Fault Depression were studied systematically, and two palynological assemblages have been recognized. Assemblage I from the Yingcheng Formation is named Paleoconiferus-Pinuspollenites; the assemblage is characterized by an extremely high content of Paleoconifer pollen. Assemblage II from Member 1 of the Denglouku Formation is named Cicatricosisporites-Cyathidites-Pinuspollenites; the assemblage is characterized by the abundant presence of Laevigati spores, but less Paleoconifer pollen. According to the palynological data and zircon U-Pb dating, the geological age of the Yingcheng Formation is thought to be Aptian-Albian, and that of the Denglouku Formation is thought to be Early Albian. On the basis of the composition of each assemblage, we can infer that during the depositional period of the Yingcheng Formation, the paleovegetation was mainly conifer forest, the paleoclimate was consistent with the temperate climate of today, and the paleoenvironment was humid feature. During the depositional period of Member 1 of the Denglouku Formation, the paleovegetation was mainly conifer forest and shrubs, the paleoclimate was consistent with the subtropical climate of today, and the paleoenvironment was humid. The results significantly improve our understanding of the stratigraphy in the Shuangliao Fault Depression, provide biostratigraphic evidence for the division and correlation of Early Cretaceous strata in the Shuangliao Fault Depression, and provide new data for analyzing paleovegetation and paleoclimate in the Songliao Basin.
