1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a u...1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a unique case among them as it evolved into the largest rift basin.The rift basin filling of SB includes Huoshiling Formation,Shahezi Formation,and Yingcheng Formation in ascending order.The mega-rifting was controlled by the Mongol-Okhotsk Collisional Belt to the north and northwest and the Pacific Subduction Zone to the east(Wang PJ et al.,2016).As the first rifting succession,the Huoshiling Formation contains key information about the formation of the rifting basins and records the evolution of the Mongol-Okhotsk Collisional Belt and the Pacific Subduction Zone.However,the geological period of the Huoshiling Formation has not been well constrained for two main reasons.First,it is easily confused with the Yingcheng Formation,as both are dominated by volcanogenic-sedimentary successions.Second,there is lack of reliable dating samples from the uppermost part of the Huoshiling Formation due to its considerable burial depth.展开更多
The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-m...The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-middle Miocene deformed rocks of the inter-Andean valley between the Western and Central Cordilleras of Colombia.However,uncertainty remains about the age of the latest accretionary phases of the Panama-ChocóBlock.Poorly studied late Miocene volcanic rocks within the northern inter-Andean valley may provide key information to constrain the temporality of that final collision.Here,we study the deformational features of the~12-6 Ma extrusive rocks of the Combia Volcanic Province located in the northwestern Andes(Colombia).We present anisotropy of magnetic susceptibility(AMS)data for pyroclastic and volcanic rocks within the AmagáBasin,an inter-Andean depression with Oligocene-middle Miocene sedimentary rocks that recorded NW-SE compression and NE-SW simple shear caused by the Panama-ChocóBlock collision.We identified that the magnetic fabrics of the extrusive rocks of the Combia Volcanic Province reveal flow directions that indicate the occurrence of ancient volcanoes in the central axis of the AmagáBasin.Some of these fabrics do not contain any deformational features,whereas others record the same structural regime as the Oligocene-middle Miocene sedimentary rocks.We infer that variations in the intensity of the deformation promoted late Miocene local fault reactivations that,in contrast to the Oligocene-middle Miocene deformational events,did not affect the entire AmagáBasin.Age differences among the studied sections can also explain the different deformational patterns identified in the basin.Both interpretations suggest that the most significant collisional events of the Panama-ChocóBlock occurred in the Oligocene-middle Miocene,whereas the formation of the Combia Volcanic Province may have either followed or coincided with the latest stages of the accretion.展开更多
The January 2022 eruption of Hunga injected unprecedented volumes of water vapor(150 Tg)and modest sulfur dioxide(SO_(2))into the stratosphere,producing accelerated sulfate aerosol formation in the early plume.As the ...The January 2022 eruption of Hunga injected unprecedented volumes of water vapor(150 Tg)and modest sulfur dioxide(SO_(2))into the stratosphere,producing accelerated sulfate aerosol formation in the early plume.As the aerosols gradually spread into the global stratosphere,the role of water vapor,among other factors in the spread and residence time of the sulfate aerosols,remained unclear.We used multisatellite observations to better understand the role of water vapor in the spread and lifetime of Hunga volcanic aerosols.Stratospheric circulation transported the plumes to~26 km within the polar vortices-the Antarctic by August 2022 and the Arctic by January 2023-with the arrival of aerosols lagging behind that of water vapor by months.Even though high injection altitudes(58 km)and strong Brewer-Dobson circulation contributed to prolonging the residence time of aerosols,the water vapor enhanced particle growth and thus accelerated gravitational settling,with the half lifetime of aerosols being 14 months.Our analysis revealed a critical trade-off:after the eruption of the Hunga volcano,an extremely high injection height and strong upward motion slowed the removal of aerosols,but extreme water vapor loading still had a certain impact on the half lifetime of the aerosols.These findings highlight the role of water vapor in the persistence of aerosols from submarine eruptions.展开更多
In recent years,significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin,highlighting their substantial exploration potential.The complex distribution of volcanic res...In recent years,significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin,highlighting their substantial exploration potential.The complex distribution of volcanic reservoirs is attributed to the multi-phase tectonic evolution within the basin,with their superior reservoir properties playing a crucial role in natural gas formation.However,due to the combined effects of multi-cyclic volcanic eruptions and tectonic activities,predicting volcanic facies distribution and favorable reservoirs remains highly challenging.This study focuses on the third member of the Jiamuhe Formation in the Zhongguai Uplift.By integrating drilling and petrophysical data with well-seismic analysis techniques,a seismic identification model for volcanic reservoirs has been established.The findings reveal that different facies exhibit distinct seismic response characteristics.Andesite,rhyolite,volcanic breccia,and volcanic clastic rocks show variability in amplitude,frequency,and continuity.Using structural-guided filtering,high-resolution coherence analysis,and 3D body carving techniques,the locations of volcanic craters and eruption centers were successfully identified,further clarifying the distribution patterns of volcanic facies.By combining multi-attribute clustering analysis and seismic attribute extraction,a volcanic facies zone distribution map was generated,and favorable exploration directions for volcanic reservoirs were proposed.The study provides technical guidance for the exploration of deep volcanic oil and gas reservoirs in the Junggar Basin and holds significant application value.展开更多
Fractures are critical control factors in volcanic reservoirs.Thus,studies on the prediction and distribution patterns of volcanic fractures are crucial for oil and gas exploration and development.Although considerabl...Fractures are critical control factors in volcanic reservoirs.Thus,studies on the prediction and distribution patterns of volcanic fractures are crucial for oil and gas exploration and development.Although considerable research has been conducted on volcanic fractures,targeted research on the spatial distribution patterns of fracture development remains limited in the literature.Two eruption modes,subaqueous eruption and subaerial eruption,have been identified in the Chaganhua subsag of the Songliao Basin,where gas resources have been discovered.Studying the differences in volcanic fracture development is highly important for understanding the law of oil and gas enrichment in volcanic reservoirs.On the basis of thin sections,cores,electrical imaging logs,and other data obtained from boreholes of subaqueous volcanic eruptions in the Songnan fault depression,we describe the characteristics of drilled fractures in detail and use 3D seismic data to extract intrinsic coherence,ant bodies,and Fourier series to extend the azimuthal anisotropic P-wave reflection coefficient,thereby predicting the spatial distribution of fractures at different scales.Moreover,through statistical analysis of quantitative evaluation indicators,such as fracture density and fracture development rate in different drilling wells,combined with the spatial distribution patterns of the predicted fractures,we compared and analyzed the relationships between the distributions of fractures and volcanic institutions,lithology,and volcanic facies.Results indicate that fractures are more developed in volcanic edifices located closer to faults.Considerable differences in fracture development are observed among lithofacies of volcanic rocks.Near faults,effusion facies,explosive facies and external clastic pyroclastic sedimentary subfacies are favorable for fracture development.This research provides a reference for investigating volcanic rock fractures of the same origins worldwide.展开更多
The Mesozoic volcanic rocks of the Bodong Low Uplift in the Bohai Bay Basin have been studied and explored for years.In 2024,the LK7-A well drilled in this region tested high-yield oil and gas flows from volcanic weat...The Mesozoic volcanic rocks of the Bodong Low Uplift in the Bohai Bay Basin have been studied and explored for years.In 2024,the LK7-A well drilled in this region tested high-yield oil and gas flows from volcanic weathered crust.These volcanic rocks need to be further investigated in terms of distribution patterns,conditions for forming high-quality reservoirs,and main factors controlling hydrocarbon accumulation.Based on the logging,geochemical and mineralogical data from wells newly drilled to the Mesozoic volcanic rocks in the basin,and high-resolution 3D seismic data,a comprehensive study was conducted for this area.The research findings are as follows.First,the volcanic rocks in the LK7-A structure are adakites with a large source area depth,and the deep and large faults have provided channels for the emplacement of intermediate-acidic volcanic rocks.Second,volcanic rock reservoirs are mainly distributed in tectonic breccias and intermediate-acidic lavas,and they are dominantly fractured-porous reservoirs,with high-porosity and low-permeability or medium-porosity and low-permeability.Third,the dominant lithologies/lithofacies is the basic condition for forming large-scale volcanic rock reservoirs.Structural fractures and late-stage strong weathering are crucial mechanisms for the formation scale of reservoirs in the Mesozoic volcanic rocks.Fourth,the Bodong Low Uplift exhibits strong hydrocarbon charging by two sags and overpressure mudstone capping,which are favorable for forming high-abundance oil and gas reservoirs.The Mesozoic volcanic buried hills in the study area reflect good trap geometry,providing favorable conditions for large-scale reservoir formation,and also excellent migration and accumulation conditions.Areas with long-term exposure of intermediate-acidic volcanic rocks,particularly in active structural regions,are the key targets for future exploration.展开更多
Volcanic ashes are posing increasingly severer threats to the aviation safety.As the operation temperature of the turbine engine elevates,molten volcanic ash leads to the degradation of the thermal barrier coatings(TB...Volcanic ashes are posing increasingly severer threats to the aviation safety.As the operation temperature of the turbine engine elevates,molten volcanic ash leads to the degradation of the thermal barrier coatings(TBCs)and eventually catastrophic engine failure.However,the physical and chemical properties of volcanic ashes vary due to the distinct chemical compositions,rendering it extremely challenging to evaluate the effects of each ash material on the failure of TBC.Here,we proposed a new metric termed Basicity to investigate the influence of chemical composition on the melting temperature and viscosity of volcanic ashes.Artificial CaO-MgO-Al_(2)O_(3)-SiO_(2) materials(CMAS)were synthesized to simulate the wetting,spreading and corrosion behavior of volcanic ashes at 1300 ℃ on(Gd_(0.9)Yb_(0.1))2Zr_(2)O_(7)(GYbZ),a model TBC material.Our results reveal that the synthetic CMAS does not fully capture the damage caused by volcanic ash due to the difference in compositions.The viscosity and characteristic temperatures decrease as the Basicity value increases,indicating its significant impact on the fusion properties of ashes.Notably,distinct from CMAS,the unexpected presence of Fe_(2)O_(3) in volcanic ashes promotes the formation of garnet phase,conversely impedes the formation of apatite dense layer.These findings provide valuable insights into the corrosion mechanisms caused by TBC and strategies for TBC protection against volcanic ashes.展开更多
The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these a...The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these ashes remain controversial.This study presents the stratigraphic distribution of volcanic ash layers,zircon trace element and Hf isotope data from the Wanhe Section in the southwestern Yangtze Shelf,providing insights into the tectonic setting and the origin of the parent magmas.The results suggest that volcanic ashes in the southwestern Yangtze Shelf primarily originated from arc magmatism in the Wuyi-Yunkai Orogen,with a mixed source from mantle and crust.The findings corroborate the hypothesis that the Late Ordovician–Silurian Wuyi-Yunkai Orogen in South China represents a collisional orogenic belt.展开更多
A prevailing theory suggests that volcanic eruptions triggered environmental changes,which compelled dinosaurs to migrate in search of new habitats.Compelling evidence for this hypothesis has now been discovered in th...A prevailing theory suggests that volcanic eruptions triggered environmental changes,which compelled dinosaurs to migrate in search of new habitats.Compelling evidence for this hypothesis has now been discovered in the Tunxi Basin of eastern China.During the Late Mesozoic,the subduction of the Pacific Plate beneath southeastern China led to multi-stage volcanic activity.The Tunxi Formation in the basin,the first reported Upper Jurassic volcanic unit in the eastern Jiangnan orogen.It overlies the stratum bearing the easternmost mamenchisaurids,which is the dominant Asian sauropod lineage.Geochemical analyses suggest its affinity with coeval magmatism in southeastern China,while new rhyolite zircon U-Pb dating yields an age of 151.6±2.2 Ma,further indicating a transition from arc magmatism to back-arc extension driven by Paleo-Pacific subduction during the Late Jurassic.These studies also confirm that,as early as 156 Ma,the Tunxi Basin was already a key habitat for mamenchisaurids.The Late Jurassic subduction of the Paleo-Pacific Plate caused extensive magmatism across eastern China.This intense tectonic shift likely induced abrupt environmental changes in relative basins.Severe volcanic activity drastically reduced the habitat of mamenchisaurids,prompting a northwestward and southward radiation trend-presents a coherent scene of volcanic eruptions,environmental catastrophe,and dinosaurs migrating.展开更多
Four types of volcanic rock samples,i.e.breccia,andesite,tuff,and dacite,selected from the Carboniferous in the Junggar Basin were characterized through experiments such as X-ray diffraction(XRD),scanning electron mic...Four types of volcanic rock samples,i.e.breccia,andesite,tuff,and dacite,selected from the Carboniferous in the Junggar Basin were characterized through experiments such as X-ray diffraction(XRD),scanning electron microscopy(SEM)and nuclear magnetic resonance(NMR)for identifying the acid imbibition and ion diffusion behaviors during fracture acidizing in volcanic rock reservoirs.The results demonstrate that the invaded acid dissolves the minerals and alters the pore structure in the reservoir.Volcanic rocks of different lithologies exhibit substantial variations in their acidification and dissolution effects.Breccia and andesite,which contain abundant calcite and other soluble minerals,show markedly improved pore connectivity after acidizing.In addition,pronounced differences are observed between the acid-induced dissolution responses of oil-rich and water-rich pores within volcanic rocks.In water-rich pores,acid-induced dissolution is dominated by H^(+)diffusion,whereas in oil-rich pores,imbibition-driven dissolution is the primary mechanism.The hydrated hydrogen-ion network formed in water-rich pores enhances H^(+)diffusion,facilitating uniform dissolution across pore scales.As a result,the pore structure becomes more homogenized,leading to a reduction in fractal dimension.In oil-rich pores,acid imbibition driven by capillary pressure is the predominant mechanism,enabling small pores to be dissolved preferentially,followed by medium to large pores.Consequently,the overall extent of acid erosion remains limited,and pore heterogeneity persists at a high level.Both the acid-imbibition and ion-diffusion processes exhibit a three-stage evolution:linear-transitional-stable.In the linear stage,the acid imbibition and H^(+)diffusion distances scale proportionally with the square root of time.In the transitional stage,the H^(+)diffusion rate decreases due to pore-throat blockage induced by the hydration and precipitation of clay minerals.Concurrently,acid imbibition and mineral dissolution enhance the fluid flow capacity,partially offsetting the attenuation of capillary pressure,and sustaining the increase in imbibition rate.In the stable stage,both acid imbibition and ion diffusion approach equilibrium.展开更多
The Ning-Wu Basin is an important part of the Middle-Lower Yangtze River Metallogenic Belt in eastern China.It contains well-preserved Mesozoic volcanic sequences that document significant geodynamic evolution.However...The Ning-Wu Basin is an important part of the Middle-Lower Yangtze River Metallogenic Belt in eastern China.It contains well-preserved Mesozoic volcanic sequences that document significant geodynamic evolution.However,uncertainties surrounding the ages of eruptions and the temporal relationships between the four main volcanic cycles—the Longwangshan,Dawangshan,Gushan and Niangniangshan formations—have hindered our understanding of magmatic pulsation and its connection to iron mineralisation.Here,high-precision LA-ICP-MS zircon U-Pb dating of four fresh volcanic samples(one per formation)reveals weighted mean ages of 132.3±1.0 Ma(Longwangshan;MSWD=1.3),130.4±1.6 Ma(Dawangshan;MSWD=1.3),128.1±1.9 Ma(Gushan;MSWD=2.0)and 127.2±1.1 Ma(Niangniangshan;MSWD=0.23).These dates constrain volcanic activity to the Early Cretaceous Valanginian-Hauterivian interval and show a systematic trend of increasingly younger ages spanning~8 Ma(133-125 Ma).This magmatism can be subdivided into three phases:initiation(133-132 Ma),peak activity(132-130 Ma)and cessation(128-125 Ma).The episodic volcanism correlates with the accelerating rollback of the Pacific subduction zone,which drives crustal melting and asthenospheric upwelling.Notably,these cycles supplied the thermal energy,fluids and iron-rich melts that were essential for the formation of porphyritic iron deposits in the basin.By establishing a highresolution chronostratigraphic framework,this study sheds light on the spatiotemporal evolution of the Ning-Wu Basin,elucidating the coupling between crust-mantle dynamics,volcanic cyclicity and ore-forming processes across eastern China’s metallogenic belt.展开更多
Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock struc...Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.展开更多
Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant...Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant lithofacies distribution,particularly the favorable areas for high-quality reservoirs,remains to be determined.In this paper,the Huoshiling Formation in the Dehui faulted depression,Songliao Basin is taken as an example to carry out the multi-scale joint characterization of its pore throat structure,establish a reservoir evaluation standard that considers both the gas content and seepage capacity,and perform reservoir evaluation and play fairway mapping under facies control.The results show that the storage space types of the gas-bearing reservoirs in the faulted depression can be ascribed into three categories and six subcategories according to the pore throat and pore characteristics.In terms of pore sizes,volcaniclastic lava rank the first,followed by volcaniclastic rocks,sedimentary volcaniclastic rocks and volcanic lava.The comprehensive evaluation parameter(Φ·K·Sg,whereΦis porosity,K permeability,and Sggas saturation)of high-quality reservoirs are all greater than 0.1.The volcanic reservoirs in the Stage-III strata are the highest in quality and largest in area of play fairways.The thermal debris flow sub-facies developed at Stage III are mainly seen along the western strike-slip fault zone in the Debei sub-sag and the southwest Nong'an tectonic belt,while those developed at Stage I are distributed along the central and eastern fault zones in the southeastern Baojia sub-sag.The favorable layer evaluation and favorable area delineation under facies control will be of certain reference significance for subsequent exploration and development of volcanic gas reservoirs.展开更多
The pore structure of rocks significantly influences the porosity and permeability of reservoirs and the migration ability of oil and gas,and being the key task on the development of volcanic gas reservoirs.Nine volca...The pore structure of rocks significantly influences the porosity and permeability of reservoirs and the migration ability of oil and gas,and being the key task on the development of volcanic gas reservoirs.Nine volcanic rock samples from the Yingcheng Formation and Huoshiling Formation in the Longfengshan area of the Changling Fault Depression in the Songliao Basin were selected for this study.The pore structures of the volcanic rocks in the study area were investigated using high-pressure mercury injection,X-ray diffraction combined with fractal theory.The relationships between the fractal dimension and physical properties characteristics,pore structure parameters,and mineral content were analyzed to provide guidance for the development of volcanic rock gas reservoirs.The results show that the reservoir can be divided into 3 types(I,II,and III)based on the shape of the capillary pressure curve,and the physical properties deteriorate successively.Different types of reservoirs exhibit different fractal characteristics.For typesⅠ,ⅡandⅢ,the average total fractal dimensions were 2.3418,2.6850,and 2.9203,respectively.The larger the fractal dimension,the stronger the heterogeneity of reservoir.A small number of macro-pores primarily contributed to permeability.The fractal dimension was negatively correlated with porosity and permeability.The fractal dimension of the rock was strongly correlated with quartz and feldspar contents,and the mineral composition and content are closely related to the pore evolution of the reservoir,which are the internal factors affecting the fractal dimension of volcanic rock.展开更多
Situated in the southwestern Pacific,the Tonga-Kermadec subduction zone is separated into two parts by the Louisvlle Ridge Seamount Chain(LRSC),i.e.,the Tanga subduction zone and the Kermadec subduction zone.Known for...Situated in the southwestern Pacific,the Tonga-Kermadec subduction zone is separated into two parts by the Louisvlle Ridge Seamount Chain(LRSC),i.e.,the Tanga subduction zone and the Kermadec subduction zone.Known for its vigorous volcanic activity,frequent large earthquakes,rapid plate subduction,and distinctive subducting plate morphology,this subduction zone provides valuable insights into its structures,dynamics,and associated geohazards.This study compiles geological and geophysical datasets in this region,including seismicity,focal mechanisms,seismic reflection and refraction profiles,and seismic tomography,to understand the relationship between lithospheric structures of the subduction system and associated seismicity-volcanic activities.Our analysis suggests that variations in overlying sediment thickness,subduction rate,and subduction angle significantly influence the lithospheric deformation processes within the Tonga-Kermadec subduction system.Furthermore,these factors contribute to the notable differences in seismicity and volcanism observed between the Tonga subduction zone and the Kermadec subduction zone.This study enhances our understanding of plate tectonics by providing insights into the interplay between subduction dynamics and lithospheric deformation,which are crucial for analyzing geological and geophysical behaviors in similar subduction environments.展开更多
Permian Kaipaileicike （开派雷兹克） volcanic rocks approximately 0-200 m thick are drilled in the Tahe （塔河） field. The distribution of volcanic rocks and their potential to form hydrocarbon reservoirs are discuss...Permian Kaipaileicike （开派雷兹克） volcanic rocks approximately 0-200 m thick are drilled in the Tahe （塔河） field. The distribution of volcanic rocks and their potential to form hydrocarbon reservoirs are discussed based on the integrated interpretation of log and 3D seismic data. The volcanic rocks, mainly consisting of dacites and basalts, are sandwiched between the Lower Triassic and Lower Carboniferous and bounded by top and bottom unconformities. The dacites accumulated in a mound shape around volcanic craters, whereas the basalts are deposited in tabular or trough-fill ge- ometries. Permian volcanic craters mainly located at the northwest corner of the Tahe field are identi- fied from volcanic rock thickening, occurrence of volcanic breccias, structural arch of the top Permian, seismic attribute anomalies, and fault （piercing conduit） reflections. Along the northwest wing of a Carboniferous salt dome, a stratigraphic trap is formed by a northeast updip pinch-out of Permian volcanic rock. Oil indications within the trap are found in numerous wells. The reservoir volcanic rocks are mainly of the fracture-pore pattern and covered by the caprock of a Lower Triassic mudstone. The hydrocarbon reservoir, which can potentially be a medium-sized oil pool, is connected to Camhrian-Ordovician source rocks through normal faults along the salt dome boundary.展开更多
Taking member one of Yingcheng Formation of Cretaceous in Xudong area, Xushen Gas Field of Songliao Basin for an example and aimed at the diachronous problem generally existed in vol- canic reservoir division, firstly...Taking member one of Yingcheng Formation of Cretaceous in Xudong area, Xushen Gas Field of Songliao Basin for an example and aimed at the diachronous problem generally existed in vol- canic reservoir division, firstly advanced the method of two steps and two unites in the researches of volcanic reservoir finely division that guided by the method that sources controlled and founded the stratigraphic trellis. In this process, volcanic edifices and bodies were identified and traced. The results indicated that aimed strata in study areas could be carved up to six layers of YCII1, YCII2, YCII-II, YCIIlI, YCIII2 and YCIIII from the top to the bottom. Analyzing causes and firmly united of well data and seismic data could achieve fine stratigraphic division of volcanic reservoir. Surfaces of layers and volcanic bodies were basically unanimous in side direction. Stratum inclination gradually reduced with the distances increased from craters. The results of volcanic reservoir division had preferable con- sistency with lithologies and volcanic lithofacies and dynamic development data. The researches offered a useful method to stratigraphic division of volcanic reservoir and it had very important significance to effective development of volcanic reservoir in practice.展开更多
A large number of seismic records are discovered for the first time in the historical materials about Wudalianchi volcanic group eruption in 1720~1721, which provides us with abundant volcanic earthquake information. ...A large number of seismic records are discovered for the first time in the historical materials about Wudalianchi volcanic group eruption in 1720~1721, which provides us with abundant volcanic earthquake information. Based on the written records, the relationship between earthquake and volcanic eruption is discussed in the paper. Fur-thermore it is pointed that earthquake swarm is an important indication of volcanic eruption. Therefore, monitoring volcanic earthquakes is of great significance for forecasting volcanic eruption.展开更多
The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data a...The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic rocks.These rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and basanites.New age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 Ma.The alkaline volcanism is younger,with ages ranging from10 to 4.5 Ma.Magmatic evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing phase.All the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic lavas.Alkaline lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional lavas.Low La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the crust.They cannot be used for discussing the mantle source of the volcanic rocks from this series.Trace elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle sources.Transitional magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic composition.This mantle source is present in all the oldest lavas from the CVL.Alkaline magmas formed from an HIMU-like mantle source,different from the Mt Cameroon HIMU mantle source.The depleted asthenospheric mantle is not involved in the Bafoussam magmatism and the two mantle sources are probably located in the lithospheric mantle,in agreement with recent geophysical models presenting the CVL as a consequence of the partial melting of the lithospheric mantle in response to edge convection along the margin of the Congo craton.展开更多
Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral...Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral contents. Based on the QAPF classification scheme given by IUGS, we propose a method to determine the mineral contents of volcanic rocks using log data and a genetic algorithm. According to the QAPF scheme, minerals in volcanic rocks are divided into five groups： Q（quartz）, A （Alkaline feldspar）, P （plagioclase）, M （mafic） and F （feldspathoid）. We propose a model called QAPM including porosity for the volumetric analysis of reservoirs. The log response equations for density, apparent neutron porosity, transit time, gamma ray and volume photoelectrical cross section index were first established with the mineral parameters obtained from the Schlumberger handbook of log mineral parameters. Then the volumes of the four minerals in the matrix were calculated using the genetic algorithm （GA）. The calculated porosity, based on the interpretation parameters, can be compared with core porosity, and the rock names given in the paper based on QAPF classification according to the four mineral contents are compatible with those from the chemical analysis of the core samples.展开更多
基金supported by the National Natural Science Foundation of China(42102135,42072140,42202122 and 41790453)Science and Technology Research Program of Chongqing Municipal Education Commission(KJZD-M202101502,KJQN202201549 and KJQN202101535)+1 种基金Natural Science Foundation of Chongqing(CSTB2022NSCQ-JQX0031 and CSTB2022NSCQMSX1586)China Scholarship Council(202208505055)。
文摘1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a unique case among them as it evolved into the largest rift basin.The rift basin filling of SB includes Huoshiling Formation,Shahezi Formation,and Yingcheng Formation in ascending order.The mega-rifting was controlled by the Mongol-Okhotsk Collisional Belt to the north and northwest and the Pacific Subduction Zone to the east(Wang PJ et al.,2016).As the first rifting succession,the Huoshiling Formation contains key information about the formation of the rifting basins and records the evolution of the Mongol-Okhotsk Collisional Belt and the Pacific Subduction Zone.However,the geological period of the Huoshiling Formation has not been well constrained for two main reasons.First,it is easily confused with the Yingcheng Formation,as both are dominated by volcanogenic-sedimentary successions.Second,there is lack of reliable dating samples from the uppermost part of the Huoshiling Formation due to its considerable burial depth.
基金supported financially by the National Natural Science Foundation of China (Grants W2433104 to V.A.P. and42225402 to J.L.)the China Postdoctoral Science Foundation(Grant 2024M753205 to V.A.P.)+4 种基金the Institute of Geology and Geophysics of the Chinese Academy of Sciences (International Fellowship for Postdoctoral Researchers, Grant 2025PD02 to V.A.P.)an association between ECOS-NORD (France)Colciencias/Icetex (Colombia)(Grant C12U01 to M.I.M.)a junior fellowship scheme of Colciencias (Colombia)(Grant 706-2015 to V.A.P.)supported the undergraduate final project of A.T
文摘The accretion of the Panama-ChocóBlock to the South American Plate partially drove the geological setting of the northern Andes.This event occurred in different collisional stages that are recorded in Oligocene-middle Miocene deformed rocks of the inter-Andean valley between the Western and Central Cordilleras of Colombia.However,uncertainty remains about the age of the latest accretionary phases of the Panama-ChocóBlock.Poorly studied late Miocene volcanic rocks within the northern inter-Andean valley may provide key information to constrain the temporality of that final collision.Here,we study the deformational features of the~12-6 Ma extrusive rocks of the Combia Volcanic Province located in the northwestern Andes(Colombia).We present anisotropy of magnetic susceptibility(AMS)data for pyroclastic and volcanic rocks within the AmagáBasin,an inter-Andean depression with Oligocene-middle Miocene sedimentary rocks that recorded NW-SE compression and NE-SW simple shear caused by the Panama-ChocóBlock collision.We identified that the magnetic fabrics of the extrusive rocks of the Combia Volcanic Province reveal flow directions that indicate the occurrence of ancient volcanoes in the central axis of the AmagáBasin.Some of these fabrics do not contain any deformational features,whereas others record the same structural regime as the Oligocene-middle Miocene sedimentary rocks.We infer that variations in the intensity of the deformation promoted late Miocene local fault reactivations that,in contrast to the Oligocene-middle Miocene deformational events,did not affect the entire AmagáBasin.Age differences among the studied sections can also explain the different deformational patterns identified in the basin.Both interpretations suggest that the most significant collisional events of the Panama-ChocóBlock occurred in the Oligocene-middle Miocene,whereas the formation of the Combia Volcanic Province may have either followed or coincided with the latest stages of the accretion.
基金funding from the National Natural Science Foundation of China(Grant Nos.U2442210 and 42275059)supported by funding from Chengdu University of Information Technology(Grant No.X202310621039).
文摘The January 2022 eruption of Hunga injected unprecedented volumes of water vapor(150 Tg)and modest sulfur dioxide(SO_(2))into the stratosphere,producing accelerated sulfate aerosol formation in the early plume.As the aerosols gradually spread into the global stratosphere,the role of water vapor,among other factors in the spread and residence time of the sulfate aerosols,remained unclear.We used multisatellite observations to better understand the role of water vapor in the spread and lifetime of Hunga volcanic aerosols.Stratospheric circulation transported the plumes to~26 km within the polar vortices-the Antarctic by August 2022 and the Arctic by January 2023-with the arrival of aerosols lagging behind that of water vapor by months.Even though high injection altitudes(58 km)and strong Brewer-Dobson circulation contributed to prolonging the residence time of aerosols,the water vapor enhanced particle growth and thus accelerated gravitational settling,with the half lifetime of aerosols being 14 months.Our analysis revealed a critical trade-off:after the eruption of the Hunga volcano,an extremely high injection height and strong upward motion slowed the removal of aerosols,but extreme water vapor loading still had a certain impact on the half lifetime of the aerosols.These findings highlight the role of water vapor in the persistence of aerosols from submarine eruptions.
文摘In recent years,significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin,highlighting their substantial exploration potential.The complex distribution of volcanic reservoirs is attributed to the multi-phase tectonic evolution within the basin,with their superior reservoir properties playing a crucial role in natural gas formation.However,due to the combined effects of multi-cyclic volcanic eruptions and tectonic activities,predicting volcanic facies distribution and favorable reservoirs remains highly challenging.This study focuses on the third member of the Jiamuhe Formation in the Zhongguai Uplift.By integrating drilling and petrophysical data with well-seismic analysis techniques,a seismic identification model for volcanic reservoirs has been established.The findings reveal that different facies exhibit distinct seismic response characteristics.Andesite,rhyolite,volcanic breccia,and volcanic clastic rocks show variability in amplitude,frequency,and continuity.Using structural-guided filtering,high-resolution coherence analysis,and 3D body carving techniques,the locations of volcanic craters and eruption centers were successfully identified,further clarifying the distribution patterns of volcanic facies.By combining multi-attribute clustering analysis and seismic attribute extraction,a volcanic facies zone distribution map was generated,and favorable exploration directions for volcanic reservoirs were proposed.The study provides technical guidance for the exploration of deep volcanic oil and gas reservoirs in the Junggar Basin and holds significant application value.
基金supported by General Projects of the Natural Science Foundation of China(41972313)major projects of the Natural Science Foundation of China(41790453)。
文摘Fractures are critical control factors in volcanic reservoirs.Thus,studies on the prediction and distribution patterns of volcanic fractures are crucial for oil and gas exploration and development.Although considerable research has been conducted on volcanic fractures,targeted research on the spatial distribution patterns of fracture development remains limited in the literature.Two eruption modes,subaqueous eruption and subaerial eruption,have been identified in the Chaganhua subsag of the Songliao Basin,where gas resources have been discovered.Studying the differences in volcanic fracture development is highly important for understanding the law of oil and gas enrichment in volcanic reservoirs.On the basis of thin sections,cores,electrical imaging logs,and other data obtained from boreholes of subaqueous volcanic eruptions in the Songnan fault depression,we describe the characteristics of drilled fractures in detail and use 3D seismic data to extract intrinsic coherence,ant bodies,and Fourier series to extend the azimuthal anisotropic P-wave reflection coefficient,thereby predicting the spatial distribution of fractures at different scales.Moreover,through statistical analysis of quantitative evaluation indicators,such as fracture density and fracture development rate in different drilling wells,combined with the spatial distribution patterns of the predicted fractures,we compared and analyzed the relationships between the distributions of fractures and volcanic institutions,lithology,and volcanic facies.Results indicate that fractures are more developed in volcanic edifices located closer to faults.Considerable differences in fracture development are observed among lithofacies of volcanic rocks.Near faults,effusion facies,explosive facies and external clastic pyroclastic sedimentary subfacies are favorable for fracture development.This research provides a reference for investigating volcanic rock fractures of the same origins worldwide.
基金Supported by the the National Natural Science Foundation of China(U24B2017)。
文摘The Mesozoic volcanic rocks of the Bodong Low Uplift in the Bohai Bay Basin have been studied and explored for years.In 2024,the LK7-A well drilled in this region tested high-yield oil and gas flows from volcanic weathered crust.These volcanic rocks need to be further investigated in terms of distribution patterns,conditions for forming high-quality reservoirs,and main factors controlling hydrocarbon accumulation.Based on the logging,geochemical and mineralogical data from wells newly drilled to the Mesozoic volcanic rocks in the basin,and high-resolution 3D seismic data,a comprehensive study was conducted for this area.The research findings are as follows.First,the volcanic rocks in the LK7-A structure are adakites with a large source area depth,and the deep and large faults have provided channels for the emplacement of intermediate-acidic volcanic rocks.Second,volcanic rock reservoirs are mainly distributed in tectonic breccias and intermediate-acidic lavas,and they are dominantly fractured-porous reservoirs,with high-porosity and low-permeability or medium-porosity and low-permeability.Third,the dominant lithologies/lithofacies is the basic condition for forming large-scale volcanic rock reservoirs.Structural fractures and late-stage strong weathering are crucial mechanisms for the formation scale of reservoirs in the Mesozoic volcanic rocks.Fourth,the Bodong Low Uplift exhibits strong hydrocarbon charging by two sags and overpressure mudstone capping,which are favorable for forming high-abundance oil and gas reservoirs.The Mesozoic volcanic buried hills in the study area reflect good trap geometry,providing favorable conditions for large-scale reservoir formation,and also excellent migration and accumulation conditions.Areas with long-term exposure of intermediate-acidic volcanic rocks,particularly in active structural regions,are the key targets for future exploration.
基金financially supported by the Nature Science Foun-dations of China(NSFC)(Nos.52401071 andU21B2052)China National Postdoctoral Program for Innovative Talents(No.BX20240459).
文摘Volcanic ashes are posing increasingly severer threats to the aviation safety.As the operation temperature of the turbine engine elevates,molten volcanic ash leads to the degradation of the thermal barrier coatings(TBCs)and eventually catastrophic engine failure.However,the physical and chemical properties of volcanic ashes vary due to the distinct chemical compositions,rendering it extremely challenging to evaluate the effects of each ash material on the failure of TBC.Here,we proposed a new metric termed Basicity to investigate the influence of chemical composition on the melting temperature and viscosity of volcanic ashes.Artificial CaO-MgO-Al_(2)O_(3)-SiO_(2) materials(CMAS)were synthesized to simulate the wetting,spreading and corrosion behavior of volcanic ashes at 1300 ℃ on(Gd_(0.9)Yb_(0.1))2Zr_(2)O_(7)(GYbZ),a model TBC material.Our results reveal that the synthetic CMAS does not fully capture the damage caused by volcanic ash due to the difference in compositions.The viscosity and characteristic temperatures decrease as the Basicity value increases,indicating its significant impact on the fusion properties of ashes.Notably,distinct from CMAS,the unexpected presence of Fe_(2)O_(3) in volcanic ashes promotes the formation of garnet phase,conversely impedes the formation of apatite dense layer.These findings provide valuable insights into the corrosion mechanisms caused by TBC and strategies for TBC protection against volcanic ashes.
基金funded by the National Natural Science Foundation of China(Nos.42222209 and 42488201)the State Scholarship Fund.
文摘The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these ashes remain controversial.This study presents the stratigraphic distribution of volcanic ash layers,zircon trace element and Hf isotope data from the Wanhe Section in the southwestern Yangtze Shelf,providing insights into the tectonic setting and the origin of the parent magmas.The results suggest that volcanic ashes in the southwestern Yangtze Shelf primarily originated from arc magmatism in the Wuyi-Yunkai Orogen,with a mixed source from mantle and crust.The findings corroborate the hypothesis that the Late Ordovician–Silurian Wuyi-Yunkai Orogen in South China represents a collisional orogenic belt.
基金supported by the China Geological Survey(DD20230221)the National Natural Science Foundation of China(42102018)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB26000000).
文摘A prevailing theory suggests that volcanic eruptions triggered environmental changes,which compelled dinosaurs to migrate in search of new habitats.Compelling evidence for this hypothesis has now been discovered in the Tunxi Basin of eastern China.During the Late Mesozoic,the subduction of the Pacific Plate beneath southeastern China led to multi-stage volcanic activity.The Tunxi Formation in the basin,the first reported Upper Jurassic volcanic unit in the eastern Jiangnan orogen.It overlies the stratum bearing the easternmost mamenchisaurids,which is the dominant Asian sauropod lineage.Geochemical analyses suggest its affinity with coeval magmatism in southeastern China,while new rhyolite zircon U-Pb dating yields an age of 151.6±2.2 Ma,further indicating a transition from arc magmatism to back-arc extension driven by Paleo-Pacific subduction during the Late Jurassic.These studies also confirm that,as early as 156 Ma,the Tunxi Basin was already a key habitat for mamenchisaurids.The Late Jurassic subduction of the Paleo-Pacific Plate caused extensive magmatism across eastern China.This intense tectonic shift likely induced abrupt environmental changes in relative basins.Severe volcanic activity drastically reduced the habitat of mamenchisaurids,prompting a northwestward and southward radiation trend-presents a coherent scene of volcanic eruptions,environmental catastrophe,and dinosaurs migrating.
基金Supported by the National Natural Science Foundation of China(52374014).
文摘Four types of volcanic rock samples,i.e.breccia,andesite,tuff,and dacite,selected from the Carboniferous in the Junggar Basin were characterized through experiments such as X-ray diffraction(XRD),scanning electron microscopy(SEM)and nuclear magnetic resonance(NMR)for identifying the acid imbibition and ion diffusion behaviors during fracture acidizing in volcanic rock reservoirs.The results demonstrate that the invaded acid dissolves the minerals and alters the pore structure in the reservoir.Volcanic rocks of different lithologies exhibit substantial variations in their acidification and dissolution effects.Breccia and andesite,which contain abundant calcite and other soluble minerals,show markedly improved pore connectivity after acidizing.In addition,pronounced differences are observed between the acid-induced dissolution responses of oil-rich and water-rich pores within volcanic rocks.In water-rich pores,acid-induced dissolution is dominated by H^(+)diffusion,whereas in oil-rich pores,imbibition-driven dissolution is the primary mechanism.The hydrated hydrogen-ion network formed in water-rich pores enhances H^(+)diffusion,facilitating uniform dissolution across pore scales.As a result,the pore structure becomes more homogenized,leading to a reduction in fractal dimension.In oil-rich pores,acid imbibition driven by capillary pressure is the predominant mechanism,enabling small pores to be dissolved preferentially,followed by medium to large pores.Consequently,the overall extent of acid erosion remains limited,and pore heterogeneity persists at a high level.Both the acid-imbibition and ion-diffusion processes exhibit a three-stage evolution:linear-transitional-stable.In the linear stage,the acid imbibition and H^(+)diffusion distances scale proportionally with the square root of time.In the transitional stage,the H^(+)diffusion rate decreases due to pore-throat blockage induced by the hydration and precipitation of clay minerals.Concurrently,acid imbibition and mineral dissolution enhance the fluid flow capacity,partially offsetting the attenuation of capillary pressure,and sustaining the increase in imbibition rate.In the stable stage,both acid imbibition and ion diffusion approach equilibrium.
基金supported by The Special Funds for Natural Resource Development in Jiangsu Province(2200113-35)The Central Financial Geological Survey Project of the China Geological Survey(DD20230800702).
文摘The Ning-Wu Basin is an important part of the Middle-Lower Yangtze River Metallogenic Belt in eastern China.It contains well-preserved Mesozoic volcanic sequences that document significant geodynamic evolution.However,uncertainties surrounding the ages of eruptions and the temporal relationships between the four main volcanic cycles—the Longwangshan,Dawangshan,Gushan and Niangniangshan formations—have hindered our understanding of magmatic pulsation and its connection to iron mineralisation.Here,high-precision LA-ICP-MS zircon U-Pb dating of four fresh volcanic samples(one per formation)reveals weighted mean ages of 132.3±1.0 Ma(Longwangshan;MSWD=1.3),130.4±1.6 Ma(Dawangshan;MSWD=1.3),128.1±1.9 Ma(Gushan;MSWD=2.0)and 127.2±1.1 Ma(Niangniangshan;MSWD=0.23).These dates constrain volcanic activity to the Early Cretaceous Valanginian-Hauterivian interval and show a systematic trend of increasingly younger ages spanning~8 Ma(133-125 Ma).This magmatism can be subdivided into three phases:initiation(133-132 Ma),peak activity(132-130 Ma)and cessation(128-125 Ma).The episodic volcanism correlates with the accelerating rollback of the Pacific subduction zone,which drives crustal melting and asthenospheric upwelling.Notably,these cycles supplied the thermal energy,fluids and iron-rich melts that were essential for the formation of porphyritic iron deposits in the basin.By establishing a highresolution chronostratigraphic framework,this study sheds light on the spatiotemporal evolution of the Ning-Wu Basin,elucidating the coupling between crust-mantle dynamics,volcanic cyclicity and ore-forming processes across eastern China’s metallogenic belt.
文摘Conventional borehole image log interpretation of linear fractures on volcanic rocks,represented as sinusoids on unwrapped cylinder projections,is relatively straight-forward,however,interpreting non-linear rock structures and complex facies geometries can be more challenging.To characterize diverse volcanic paleoenvironments related to the formation of the South American continent,this study presents a new methodology based on image logs,petrography,seismic data,and outcrop analogues.The presented methodology used pseudo-boreholes images generated from outcrop photographs with typical igneous rock features worldwide simulating 2D unwrapped cylinder projections of a 31 cm(12.25 in)diameter well.These synthetic images and standard outcrop photographs were used to define morphological patterns of igneous structures and facies for comparison with wireline borehole image logs from subsurface volcanic and subvolcanic units,providing a“visual scale”for geological evaluation of volcanic facies,significantly enhancing the identification efficiency and reliability of complex geological structures.Our analysis focused on various scales of columnar jointing and pillow lava lobes with additional examples including pahoehoe lava,ignimbrite,hyaloclastite,and various intrusive features in Campos,Santos,and Parnaíba basins in Brazil.This approach increases confidence in the interpretation of subvolcanic,subaerial,and subaqueous deposits.The image log interpretation combined with regional geological knowledge has enabled paleoenvironmental insights into the rift magmatism system related to the breakup of Gondwana with associated implications for hydrocarbon exploration.
基金funded by the National Natural Science Foundation of China(No.42172145)Natural Science Foundation of Heilongjiang Provincial(No.LH2022D014)。
文摘Volcanic reservoirs demonstrate strong heterogeneity and substantial variations in productivity due to the complexity of volcanic eruption and lithology.The main types of reservoir space are not clear,and the dominant lithofacies distribution,particularly the favorable areas for high-quality reservoirs,remains to be determined.In this paper,the Huoshiling Formation in the Dehui faulted depression,Songliao Basin is taken as an example to carry out the multi-scale joint characterization of its pore throat structure,establish a reservoir evaluation standard that considers both the gas content and seepage capacity,and perform reservoir evaluation and play fairway mapping under facies control.The results show that the storage space types of the gas-bearing reservoirs in the faulted depression can be ascribed into three categories and six subcategories according to the pore throat and pore characteristics.In terms of pore sizes,volcaniclastic lava rank the first,followed by volcaniclastic rocks,sedimentary volcaniclastic rocks and volcanic lava.The comprehensive evaluation parameter(Φ·K·Sg,whereΦis porosity,K permeability,and Sggas saturation)of high-quality reservoirs are all greater than 0.1.The volcanic reservoirs in the Stage-III strata are the highest in quality and largest in area of play fairways.The thermal debris flow sub-facies developed at Stage III are mainly seen along the western strike-slip fault zone in the Debei sub-sag and the southwest Nong'an tectonic belt,while those developed at Stage I are distributed along the central and eastern fault zones in the southeastern Baojia sub-sag.The favorable layer evaluation and favorable area delineation under facies control will be of certain reference significance for subsequent exploration and development of volcanic gas reservoirs.
基金Supported by Key Scientific and Technological Projects of Sinopec(No.P21104-2).
文摘The pore structure of rocks significantly influences the porosity and permeability of reservoirs and the migration ability of oil and gas,and being the key task on the development of volcanic gas reservoirs.Nine volcanic rock samples from the Yingcheng Formation and Huoshiling Formation in the Longfengshan area of the Changling Fault Depression in the Songliao Basin were selected for this study.The pore structures of the volcanic rocks in the study area were investigated using high-pressure mercury injection,X-ray diffraction combined with fractal theory.The relationships between the fractal dimension and physical properties characteristics,pore structure parameters,and mineral content were analyzed to provide guidance for the development of volcanic rock gas reservoirs.The results show that the reservoir can be divided into 3 types(I,II,and III)based on the shape of the capillary pressure curve,and the physical properties deteriorate successively.Different types of reservoirs exhibit different fractal characteristics.For typesⅠ,ⅡandⅢ,the average total fractal dimensions were 2.3418,2.6850,and 2.9203,respectively.The larger the fractal dimension,the stronger the heterogeneity of reservoir.A small number of macro-pores primarily contributed to permeability.The fractal dimension was negatively correlated with porosity and permeability.The fractal dimension of the rock was strongly correlated with quartz and feldspar contents,and the mineral composition and content are closely related to the pore evolution of the reservoir,which are the internal factors affecting the fractal dimension of volcanic rock.
基金supported by Special Projects in Universities’Key Fields of Guangdong Province(No.2023ZDZX3017)the 2022 Tertiary Education Scientific Research Project of Guangzhou Municipal Education Bureau(No.202234607)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2025A1515012983)the National Natural Science Foundation of China(Nos.52371059 and 52101358).
文摘Situated in the southwestern Pacific,the Tonga-Kermadec subduction zone is separated into two parts by the Louisvlle Ridge Seamount Chain(LRSC),i.e.,the Tanga subduction zone and the Kermadec subduction zone.Known for its vigorous volcanic activity,frequent large earthquakes,rapid plate subduction,and distinctive subducting plate morphology,this subduction zone provides valuable insights into its structures,dynamics,and associated geohazards.This study compiles geological and geophysical datasets in this region,including seismicity,focal mechanisms,seismic reflection and refraction profiles,and seismic tomography,to understand the relationship between lithospheric structures of the subduction system and associated seismicity-volcanic activities.Our analysis suggests that variations in overlying sediment thickness,subduction rate,and subduction angle significantly influence the lithospheric deformation processes within the Tonga-Kermadec subduction system.Furthermore,these factors contribute to the notable differences in seismicity and volcanism observed between the Tonga subduction zone and the Kermadec subduction zone.This study enhances our understanding of plate tectonics by providing insights into the interplay between subduction dynamics and lithospheric deformation,which are crucial for analyzing geological and geophysical behaviors in similar subduction environments.
基金supported by the SINOPEC Forward Looking Project (No. YPH08114)the National Key Project of China(No. 2011zx05001-003)
文摘Permian Kaipaileicike （开派雷兹克） volcanic rocks approximately 0-200 m thick are drilled in the Tahe （塔河） field. The distribution of volcanic rocks and their potential to form hydrocarbon reservoirs are discussed based on the integrated interpretation of log and 3D seismic data. The volcanic rocks, mainly consisting of dacites and basalts, are sandwiched between the Lower Triassic and Lower Carboniferous and bounded by top and bottom unconformities. The dacites accumulated in a mound shape around volcanic craters, whereas the basalts are deposited in tabular or trough-fill ge- ometries. Permian volcanic craters mainly located at the northwest corner of the Tahe field are identi- fied from volcanic rock thickening, occurrence of volcanic breccias, structural arch of the top Permian, seismic attribute anomalies, and fault （piercing conduit） reflections. Along the northwest wing of a Carboniferous salt dome, a stratigraphic trap is formed by a northeast updip pinch-out of Permian volcanic rock. Oil indications within the trap are found in numerous wells. The reservoir volcanic rocks are mainly of the fracture-pore pattern and covered by the caprock of a Lower Triassic mudstone. The hydrocarbon reservoir, which can potentially be a medium-sized oil pool, is connected to Camhrian-Ordovician source rocks through normal faults along the salt dome boundary.
基金sponsored by the Magnitude Project of Ministry of Science and Technology of China (No. 2008ZX05016-001)the China Postdoctoral Science Foundation (No. 20100480344)Youth Innovation Fund of Research Institute of Petroleum Exploration and Development of PetroChina (No. 2009-B-10-03)
文摘Taking member one of Yingcheng Formation of Cretaceous in Xudong area, Xushen Gas Field of Songliao Basin for an example and aimed at the diachronous problem generally existed in vol- canic reservoir division, firstly advanced the method of two steps and two unites in the researches of volcanic reservoir finely division that guided by the method that sources controlled and founded the stratigraphic trellis. In this process, volcanic edifices and bodies were identified and traced. The results indicated that aimed strata in study areas could be carved up to six layers of YCII1, YCII2, YCII-II, YCIIlI, YCIII2 and YCIIII from the top to the bottom. Analyzing causes and firmly united of well data and seismic data could achieve fine stratigraphic division of volcanic reservoir. Surfaces of layers and volcanic bodies were basically unanimous in side direction. Stratum inclination gradually reduced with the distances increased from craters. The results of volcanic reservoir division had preferable con- sistency with lithologies and volcanic lithofacies and dynamic development data. The researches offered a useful method to stratigraphic division of volcanic reservoir and it had very important significance to effective development of volcanic reservoir in practice.
文摘A large number of seismic records are discovered for the first time in the historical materials about Wudalianchi volcanic group eruption in 1720~1721, which provides us with abundant volcanic earthquake information. Based on the written records, the relationship between earthquake and volcanic eruption is discussed in the paper. Fur-thermore it is pointed that earthquake swarm is an important indication of volcanic eruption. Therefore, monitoring volcanic earthquakes is of great significance for forecasting volcanic eruption.
文摘The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic rocks.These rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and basanites.New age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 Ma.The alkaline volcanism is younger,with ages ranging from10 to 4.5 Ma.Magmatic evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing phase.All the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic lavas.Alkaline lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional lavas.Low La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the crust.They cannot be used for discussing the mantle source of the volcanic rocks from this series.Trace elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle sources.Transitional magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic composition.This mantle source is present in all the oldest lavas from the CVL.Alkaline magmas formed from an HIMU-like mantle source,different from the Mt Cameroon HIMU mantle source.The depleted asthenospheric mantle is not involved in the Bafoussam magmatism and the two mantle sources are probably located in the lithospheric mantle,in agreement with recent geophysical models presenting the CVL as a consequence of the partial melting of the lithospheric mantle in response to edge convection along the margin of the Congo craton.
基金National Natural Science Foundation of China (No. 49894194-4)
文摘Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral contents. Based on the QAPF classification scheme given by IUGS, we propose a method to determine the mineral contents of volcanic rocks using log data and a genetic algorithm. According to the QAPF scheme, minerals in volcanic rocks are divided into five groups： Q（quartz）, A （Alkaline feldspar）, P （plagioclase）, M （mafic） and F （feldspathoid）. We propose a model called QAPM including porosity for the volumetric analysis of reservoirs. The log response equations for density, apparent neutron porosity, transit time, gamma ray and volume photoelectrical cross section index were first established with the mineral parameters obtained from the Schlumberger handbook of log mineral parameters. Then the volumes of the four minerals in the matrix were calculated using the genetic algorithm （GA）. The calculated porosity, based on the interpretation parameters, can be compared with core porosity, and the rock names given in the paper based on QAPF classification according to the four mineral contents are compatible with those from the chemical analysis of the core samples.
