Growth of ln0.52Al0.48As epitaxial layers on lnP(100) substrates by molecular beam epitaxy at a wide range of arsenic overpressures (V/III flux ratios from 30 to 300) has been carried out. Analysis performed using low...Growth of ln0.52Al0.48As epitaxial layers on lnP(100) substrates by molecular beam epitaxy at a wide range of arsenic overpressures (V/III flux ratios from 30 to 300) has been carried out. Analysis performed using low-temperature photoluminescence (PL) and double-axis X-ray diffraction (XRD) shows a strong and prominent dependence of the PL and XRD linewidths on the V/III flux ratio. Under our growth conditions, both the PL and XRD linewidths exhibit a minimum point at a V/III flux ratio of 150 which corresponds to a maximum in the PL intensity and XRD intensity ratio. Flux ratios exceeding 150 result in an increase in both the PL and XRD linewidths corresponding to a reduction in their associated intensities. Room temperature Raman scattering measurements show a narrowing in the lnAs-like and AlAs-like longitudinal-optic (LO)phonon linewidths which broaden at high flux ratios, while the LO phonon frequencies exhibit a gradual reduction as the flux ratio is increased. PL spectra taken at increasing temperatures show a quenching of the main emission peak followed by the evolution of a broad lower energy emission which is possibly associated with deep lying centres. This effect is more prominent in samples grown at lower V/III flux ratios. Hall effect measurements show a gradual reduction in the mobility in correspondence to an increase in the electron concentration as the flux ratio is increased.展开更多
Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads ...Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.展开更多
The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personn...The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personnel from firing artillery within the cab.To investigate the overpressure characteristics of the FFICC,a foreign trade equipment model was used as the research object,and a numerical model was established to analyze the propagation of muzzle blast from the muzzle to the interior of the crew compartment under extreme firing condition.For comparative verification,the muzzle blast experiment included overpressure data from both the flow field outside the crew compartment(FFOCC)and the FFICC,as well as the acceleration data of the crew compartment structure(Str-CC).The research findings demonstrate that the overpressure-time curves of the FFICC exhibit multi-peak characteristics,while the pressure wave shows no significant discontinuity.The enclosed nature of the cab hinders the dissipation of pressure wave energy within the FFICC,leading to sustained high-amplitude overpressure.The frameskin structure helps attenuate the impact of muzzle blast on the FFICC.Conversely,local high overpressure caused by the convex or concave features of the cab's exterior significantly amplifies the overpressure amplitude within the FFICC.展开更多
Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accur...Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accurate overpressure prediction remains challenging in offshore Northwest Borneo despite several decades of drilling experience.This paper focuses on two exploration wells drilled by Brunei Shell Petroleum 40 years apart that faced similar challenges with overpressure prediction and well control.An integrated lookback study is attempted using seismic and well-log data to explore the causes of the unsatisfactory Pore Pressure Prediction(PPP)outcome in pre-drill and real-time operation settings for thesewells.Our study indicates that the misprediction of overpressures is due to real differences in shale pressure(basis of pre-drill work and monitoring)and sand pressure(source of drill kick and well control chal-lenges)due to large-scale vertical leak or expulsion of deep-seated fluids into pre-compacted normally pressured overlying sediments in several regions through a mix of shear and tensile failure mechanisms.Such migrated fluids inflate the sand pressure in the normally compacted shallower sequences with the shale pressure remaining low.A predictive framework for upward fluid expulsion was attempted but found impracticable due to complex spatial and temporal variations in the horizontal stress field responsible for such leakage.As such,it is proposed that these migratory overpressures are essentially'unpredictable'from conventional PPP workflows viewed in the broad bucket of compaction disequi-librium(undercompaction)and fluid expansion(unloading)mechanisms.Further study is recommended to understand if such migrated overpressures in the sand can produce a discernible and predictable geophysical or petrophysical signature in the abutting normally compacted shales.The study highlights the possibility of large lateral variability in the sand overpressure within the same stratigraphic unit in regions with complex tectonostratigraphic evolution like Northwest Borneo.展开更多
Gas explosions are a frequent hazard in underground confined spaces in the process of urban development.Liquid sedimentary layers,commonly present in these environments,have not been sufficiently studied in terms of t...Gas explosions are a frequent hazard in underground confined spaces in the process of urban development.Liquid sedimentary layers,commonly present in these environments,have not been sufficiently studied in terms of their impact on explosion dynamics.This study aims to investigate how gas-liquid two-phase environments in confined underground spaces affect the explosion characteristics of natural gas.To achieve this,experiments are conducted to examine the propagation of natural gas explosions in water and diesel layers,focusing on the influence of liquid properties and the liquid fullness degree(Lx)on explosion behavior.The results indicate that the presence of a liquid layer after the initial ignition stage significantly attenuates both the peak overpressure and the rise speed of pressure,in comparison to the natural gas conditions.During the subsequent explosive reaction,the evaporation and combustion of the diesel surface resulted in a distinct double-peak pressure rise profile in the diesel layer,with the second peak notably exceeding the first peak.Under conditions with a liquid sedimentary layer,the flame propagation velocities range from 6.53 to 34.1 m/s,while the overpressure peaks vary between 0.157 and 0.255 MPa.The explosion duration in both the water and diesel layer environments is approximately twice as long as that of the natural gas explosion,although the underlying mechanisms differ.In the diesel layer,the prolonged explosion time is attributed to the evaporation and combustion of the diesel,while in the water layer,the flame propagation velocity is significantly reduced.Under the experimental conditions,the maximum explosion energy reached 7.15×10~6J,corresponding to a TNT equivalent of 1.7.The peak overpressure surpassed the threshold for human fatality as defined by overpressure standards,posing a potential risk of damage to large steel-frame structures.The explosion shockwave in diesel layer conditions(L_(d)=0%,5%,7.5%,12.5%)and water layer(L_(w)=12.5%)conditions is observed to be sufficient to damage earthquake-resistant reinforced concrete.This study investigates the impact of sediment layer thickness and composition on gas explosions,and evaluates the associated explosion energy to assess human injuries and structural damage in underground environments.The findings of this study provide a scientific reference for urban underground safety.展开更多
To explore the design criteria for composite charges and reveal the intrinsic relationship between the detonation wave propagation in composite charges and the overall energy distribution of shock waves,this study ana...To explore the design criteria for composite charges and reveal the intrinsic relationship between the detonation wave propagation in composite charges and the overall energy distribution of shock waves,this study analyzes the propagation and interaction processes of detonation waves in composite charges with different structural dimensions and explosive combinations. It also investigates the spatial distribution characteristics of the resulting shock wave loads. Based on dimensional analysis theory, a theoretical analysis of the shock wave overpressure distribution in free air fields is conducted. Utilizing the derived dimensionless function relationships, the hydrocode AUTODYN is employed to investigate the effects of charge structure parameters and explosive combinations on the internal overdriven detonation phenomena and the distribution of shock wave loads. It is found that the overdriven detonation phenomenon in the inner layer of composite charges increases the strength of the axial detonation wave,thereby enhancing the intensity of the primary end wave formed upon refraction into the air, which affects the distribution characteristics of the shock wave overpressure. Research has shown that increasing the thickness ratio and detonation velocity ratio of composite charges is beneficial for exacerbating the phenomenon of overdriven detonation, improving the primary end wave intensity and axial overpressure. This gain effect gradually weakens with the propagation of shock waves. When overdriven detonation occurs inside the composite charge, the detonation pressure first increases and then decreases. The Mach reflection pressure of the composite charge with a larger aspect ratio is attenuated to a greater extent. In addition, as the aspect ratio of the composite charge increases, the shock wave energy gradually flows from the axial direction to the radial direction. Therefore, as the aspect ratio of the composite charge increases, the primary end wave intensity and axial overpressure gradually decrease.展开更多
It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure.Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression.However,due to l...It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure.Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression.However,due to limited degree of exploration,there are some problems in the study area,such as unclear understanding of the origin of overpressure and the vague investigation of overpressure evolution.To clarify the impact of overpressure on oil and gas migration and accumulation in the study area,this study focuses on the research of the origin and evolution of overpressure in the Shahezi Formation of the study area,utilizing single well logging parameters and combining methods such as microthermometry of fluid inclusions,laser Raman spectrum,and basin simulation.The results show that the overpressure of the Shahezi Formation in Xujiaweizi fault depression is primarily generated by hydrocarbon generation pressurization,and the evolution of overpressure is closely related to hydrocarbon generation.The development of overpressure can be divided into two evolutionary stages:early hydrocarbon generation pressurization and late uplift release,with slight variations in different regions.Tight glutenite gas reservoirs in the Shahezi Formation are characterized by continuous charging.The overall charging period ranges from the late Denglouku to the early Mingshui(110-67 Ma ago).There is an obvious paleo-overpressure during the gas reservoir formation period.The gas generation period of source rocks occurred approximately 125-60 Ma ago,and the main gas generation period(112-67 Ma ago)highly coincides with the period of natural gas charging.The anomalously high pressure during the accumulation period is considered the significant driving force for natural gas charging.In addition,the sustained effect of overpressure provides better conditions for the preservation of tight gas reservoirs within the source.The results of the study are of guiding significance for the in-depth exploration and development of deep tight sandstone gas in the Shahezi Formation of Xujiaweizi fault depression.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
Much progress in the studies on overpressuring mechanisms has been made during the past one to two decades.(1)The causes of overpressure are divided into five categories,namely,disequilibrium compaction,fluid expansio...Much progress in the studies on overpressuring mechanisms has been made during the past one to two decades.(1)The causes of overpressure are divided into five categories,namely,disequilibrium compaction,fluid expansion,diagenesis,tectonic compression and pressure transfer.The fluid expansion involves hydrocarbon generation,oil cracking to gas and hydrothermal expansion.The diagenesis includes smectite-to-illite transformation.(2)Six methods for identifying overpressure origin are proposed,including log curves combination analysis,Bowers method(loading-unloading diagram),velocitydensity crossplotting,correlation of porosities,pressure calculation and correlation,and comprehensive analyses.(3)With more and more application of empirical methods in the study of overpressure formation,almost all of the overpressure cases that are traditionally thought to be caused by disequilibrium compaction are denied totally or partly.Instead,the hydrocarbon generation is demonstrated to be the most significant mechanism for overpressure formation;the clay diagenesis(especially the smectiteillite transformation)as well as tectonic compression and pressure transfer are also important for overpressure formation.In addition,the overpressure formation in many basins is thought to be influenced by the combination of two or more overpressuring mechanisms.(4)Causes of overpressuring differ in lithology;for mudstones,the overpressure formation in source rocks is usually different from that of non-source rocks,the former of which is frequently related to hydrocarbon generation and sometimes also affected by diagenesis,while the later of which is commonly related to disequilibrium compaction,diagenesis and pressure transfer;for permeable rocks such as sandstones,overpressure is mainly caused by pressure transfer.(5)Because organic matter has an obvious influence on logging parameters such as density and acoustic velocity,an appropriate correction on the content of organic matter is needed when these logging data are used to analyze overpressure formation in organic-rich mudstones.It has been revealed that the cause of overpressuring based on the corrected log data can be quite different from that without correction.展开更多
Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in diff...Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in different regions.The above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP program.The results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP waveform.Through dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was obtained.According to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are set.The above results can provide a reference for the design and construction of the reinforced concrete blast wall.展开更多
As a kind of high-efficiency explosive with compound destructive capability, the energy output law of thermobaric explosives has been receiving great attention. In order to investigate the effects of main components o...As a kind of high-efficiency explosive with compound destructive capability, the energy output law of thermobaric explosives has been receiving great attention. In order to investigate the effects of main components on the explosive characteristics of thermobaric explosives, various high explosives and oxidants were selected to formulate five different types of thermobaric explosive. Then they were tested in both open space and closed space respectively. Pressure measurement system, high-speed camera,infrared thermal imager and multispectral temperature measurement system were used for pressure,temperature and fireball recording. The effects of different components on the explosive characteristics of thermobaric explosive were analyzed. The results showed that in open space, the overpressure is dominated by the high explosives content in the formulation. The addition of the oxidants will decrease the explosion overpressure but will increase the duration and overall brightness of the fireball. While in closed space, the quasi-static pressure formed after the explosion is positively correlated with the temperature and gas production. In addition, it was found that the differences in shell constraints can also alter the afterburning reaction of thermobaric explosives, thus affecting their energy output characteristics. PVC shell constraint obviously increases the overpressure and makes the fireball burn more violently.展开更多
Based on the observation and analysis of cores and thin sections,and combined with cathodoluminescence,laser Raman,fluid inclusions,and in-situ LA-ICP-MS U-Pb dating,the genetic mechanism and petroleum geological sign...Based on the observation and analysis of cores and thin sections,and combined with cathodoluminescence,laser Raman,fluid inclusions,and in-situ LA-ICP-MS U-Pb dating,the genetic mechanism and petroleum geological significance of calcite veins in shales of the Cretaceous Qingshankou Formation in the Songliao Basin were investigated.Macroscopically,the calcite veins are bedding parallel,and show lenticular,S-shaped,cone-in-cone and pinnate structures.Microscopically,they can be divided into syntaxial blocky or columnar calcite veins and antitaxial fibrous calcite veins.The aqueous fluid inclusions in blocky calcite veins have a homogenization temperature of 132.5–145.1℃,the in-situ U-Pb dating age of blocky calcite veins is(69.9±5.2)Ma,suggesting that the middle maturity period of source rocks and the conventional oil formation period in the Qingshankou Formation are the sedimentary period of Mingshui Formation in Late Cretaceous.The aqueous fluid inclusions in fibrous calcite veins with the homogenization temperature of 141.2–157.4℃,yields the U-Pb age of(44.7±6.9)Ma,indicating that the middle-high maturity period of source rocks and the Gulong shale oil formation period in the Qingshankou Formation are the sedimentary period of Paleocene Yi'an Formaiton.The syntaxial blocky or columnar calcite veins were formed sensitively to the diagenetic evolution and hydrocarbon generation,mainly in three stages(fracture opening,vein-forming fluid filling,and vein growth).Tectonic extrusion activities and fluid overpressure are induction factors for the formation of fractures,and vein-forming fluid flows mainly as diffusion in a short distance.These veins generally follow a competitive growth mode.The antitaxial fibrous calcite veins were formed under the driving of the force of crystallization in a non-competitive growth environment.It is considered that the calcite veins in organic-rich shale of the Qingshankou Formation in the study area has important implications for local tectonic activities,fluid overpressure,hydrocarbon generation and expulsion,and diagenesis-hydrocarbon accumulation dating of the Songliao Basin.展开更多
The enrichment and development of shale oil are significantly influenced by the evolution of clay minerals.In this paper,the mineralogy and clay mineral crystallinity of shale samples from Wells X1,X2 and X3 in the Gu...The enrichment and development of shale oil are significantly influenced by the evolution of clay minerals.In this paper,the mineralogy and clay mineral crystallinity of shale samples from Wells X1,X2 and X3 in the Gulong Sag are characterized by X-ray diffraction analysis(XRD)and field emission scanning electron microscopy(FE-SEM).Geochemical parameters,including total organic carbon(TOC)and rock-eval pyrolysis,were also evaluated.The results reveal that illite in the shale primarily exists in the matrix,originating mainly from the transformation of smectite and I/S mixed layer.Chlorite in pores is predominantly formed through fluid precipitation and crystallization.The study area exhibits abnormal evolution of illite and I/S mixed layers,as well as the phenomenon of rapid chlorite growth under overpressure condition.The abnormal evolution of illite and I/S mixed layer may attribute to the inhibition of the conversion reaction from I/S mixed layer to illite.Chlorite's rapid growth occurs through the nucleation mechanism.Furthermore,through the analysis of clay and organic matter correlation,coupled with overpressure and hydrocarbon-rich section considerations,it is observed that chlorite may play a significant role in the storage and generation of S1.This study contributes to a better understanding of the relationship between clay mineral evolution and shale reservoir overpressure,offering valuable insights for the accurate assessment of shale oil.展开更多
Based on the data from 3D seismic surveys,drilling,sidewall coring,thin sections,and tests,this paper analyzes Meso-Cenozoic geotectonic dynamics,buried-hill reservoir characteristics,and differential enrichment patte...Based on the data from 3D seismic surveys,drilling,sidewall coring,thin sections,and tests,this paper analyzes Meso-Cenozoic geotectonic dynamics,buried-hill reservoir characteristics,and differential enrichment patterns of oil and gas in the buried hills,as well as case studies of typical reservoirs,to systematically discuss the conditions required for the formation of buried-hills and reservoirs and accumulations in the large oil and gas fields in deep to ultra-deep composite buried hills in the Bohai Sea..The key findings are as follows.First,deep to ultra-deep composite buried hills developed in the offshore Bohai Bay Basin primarily due to the double-episode destruction of the North China Craton in the Yanshanian and Himalayan.The Tanlu Fault's activity and the destruction of the North China Craton worked together to create the destruction center,which moved and converged episodically from the Bohai Bay Basin's margins towards the Bozhong Sag.This led to the formation of two development zones for composite buried hills and an orderly process of mountain-building within the offshore Bohai Bay Basin and subsequently two development zones for composite buried hills,i.e.the middle and inner rim zones within the Bozhong Depression.Second,under the coupling of favorable lithologies and multi-stage structures,the middle and inner rim zones are favorable for the formation of reservoirs in fluid dissolution-pore/fracture zones underlying the weathering crust.Third,Massive hydrocarbons were produced along the middle and inner rim zones during the Episode Ⅱ craton destruction,which caused overpressure.These hydrocarbons then moved to and accumulated in the composite buried hills.Excellent conditions for the accumulation of hydrocarbons are still present in the interior and lower portions of these buried hills.These results encourage a change in buried hill research to investigate composite buried hills in three dimensions.It should be noted that the multi-stage volcanic structures in the inner rim zone of the Sag and the deep to ultra-deep composite buried hill interiors in the middle rim zone are significant successor areas for further Bohai Sea exploration.展开更多
Overpressure is widely developed in deep petroliferous strata in the hinterland of the Junggar Basin.However,a comprehensive understanding of its origin and effect on hydrocarbon distribution and enrichment remains la...Overpressure is widely developed in deep petroliferous strata in the hinterland of the Junggar Basin.However,a comprehensive understanding of its origin and effect on hydrocarbon distribution and enrichment remains lacking.In this study,we employ five empirical methods and comprehensive geological analysis to identify the origin of overpressure,and uncover the effect of overpressure on hydrocarbon enrichment.The results indicate that disequilibrium compaction is not a significant factor in overpressure generation.Instead,hydrocarbon generation,pressure transfer and diagenesis are the primary causes.The empirical methods support this conclusion.There is a positive correlation between overpressure intensity and source rock thickness and maturity.Notably,widespread cross-formational migration of hydrocarbon bearing fluid occurred,with sandstone overpressure exceeding that of adjacent shale in non-source strata.Furthermore,there is a distinct transformation from smectite to illite near the top of overpressure.Hydrocarbon generation pressurization and pressure transfer significantly effect hydrocarbon enrichment.The overpressure caused by hydrocarbon generation drives hydrocarbon migration and accumulation,establishing an optimal energy configuration between reservoir and cap rock.Faults play a crucial role in hydrocarbon vertical migration and pressure relief.The overpressure in reservoirs can reduce the porosity and permeability thresholds and enhance the charging capacity of oil and gas.展开更多
A direct comparison is made between the effectiveness of Al,Mg,and Be powders as additional fuels in model thermobaric compositions containing 20%fuel,20%ammonium perchlorate,and 60%RDX(1,3,5-Trinitro-1,3,5-triazacycl...A direct comparison is made between the effectiveness of Al,Mg,and Be powders as additional fuels in model thermobaric compositions containing 20%fuel,20%ammonium perchlorate,and 60%RDX(1,3,5-Trinitro-1,3,5-triazacyclohexane)passivated with wax.Experimentally determined calorimetric measurements of the heat of detonation,along with the overpressure histories in an explosion chamber filled with nitrogen,were used to determine the quasi-static pressure(QSP)under anaerobic conditions.Overpressure measurements were also performed in a semi-closed bunker,and all blast wave parameters generated after the detonation of 500 g charges of the tested explosives were determined.Detonation calorimetry results,QSP values,and blast wave parameters(pressure amplitude,specific and total impulses)clearly indicate that Be is much more effective as an additional fuel than either Al or Mg in both anaerobic post-detonation reactions as well as the subsequent aerobic combustion.The heat of detonation of the RDXwax/AP/Be explosive mixture is over 40%and 50%higher than that of the mixture containing aluminum and magnesium instead of beryllium,respectively.Moreover,the TNT equivalent of the Be-containing composition due to the overpressure in the nitrogen-filled explosion chamber is 1.66,while the equivalent calculated using an air shock wave-specific impulse at a distance of 2.5 m is equal to 1.69.The high values of these parameters confirm the high reactivity of beryllium in both the anaerobic and aerobic stages of the thermobaric explosion.展开更多
The accurate prediction of peak overpressure of explosion shockwaves is significant in fields such as explosion hazard assessment and structural protection, where explosion shockwaves serve as typical destructive elem...The accurate prediction of peak overpressure of explosion shockwaves is significant in fields such as explosion hazard assessment and structural protection, where explosion shockwaves serve as typical destructive elements. Aiming at the problem of insufficient accuracy of the existing physical models for predicting the peak overpressure of ground reflected waves, two physics-informed machine learning models are constructed. The results demonstrate that the machine learning models, which incorporate physical information by predicting the deviation between the physical model and actual values and adding a physical loss term in the loss function, can accurately predict both the training and out-oftraining dataset. Compared to existing physical models, the average relative error in the predicted training domain is reduced from 17.459%-48.588% to 2%, and the proportion of average relative error less than 20% increased from 0% to 59.4% to more than 99%. In addition, the relative average error outside the prediction training set range is reduced from 14.496%-29.389% to 5%, and the proportion of relative average error less than 20% increased from 0% to 71.39% to more than 99%. The inclusion of a physical loss term enforcing monotonicity in the loss function effectively improves the extrapolation performance of machine learning. The findings of this study provide valuable reference for explosion hazard assessment and anti-explosion structural design in various fields.展开更多
In quartzo-feldspathic continental crust with moderate-to-high heat flow,seismic activity extends to depths of 10-20 km,bounded by isotherms in the 350-450 C range.Fluid overpressuring above hydrostatic in seismogenic...In quartzo-feldspathic continental crust with moderate-to-high heat flow,seismic activity extends to depths of 10-20 km,bounded by isotherms in the 350-450 C range.Fluid overpressuring above hydrostatic in seismogenic crust,is heterogeneous but tends to develop in the lower seismogenic zone(basal seismogenic zone reservoir=b.s.z.reservoir) where the transition between hydrostatically pressured and overpressured crust is likely an irregular,time-dependent.3-D interface with overpressuring concentrated around active faults and their ductile shear zone roots.The term Arterial Fault is applied to fault structures that root in portions of the crust where pore fluids are overpressured(i.e.at> hydrostatic pressure) and serve as feeders for such fluids and their contained solutes into overlying parts of the crust.While arterial flow may occur on any type of fault,it is most likely to be associated with reverse faults in areas of horizontal compression where fluid overpressuring is most easily sustained.Frictional stability and flow permeability of faults are both affected by the state of stress on the fault(shear stress,τ;normal stress,σn),the level of pore-fluid pressure,Pf,and episodes of fault slip,allowing for a complex interplay between fault movement and fluid flow.For seismically active faults the time dependence of permeability is critical,leading to fault-valve behaviour whereby overpressures accumulate at depth during interseismic intervals with fluid discharged along enhanced fault-fracture permeability following each rupture event.Patterns of mineralization also suggest that flow along faults is non-uniform,concentrating along tortuous pathways within the fault surface.Equivalent hydrostatic head above ground level for near-lithostatic overpressures at depth(<1.65×depth of zone) provides a measure of arterial potential.Settings for arterial faults include fault systems developed in compacting sedimentary basins,faults penetrating zones of active plutonic intrusion that encounter overpressured fluids exsolved from magma,together with those derived from contact metamorphism of fluid-rich wallrocks,and/or from regional devolatilisation accompanying prograde metamorphism.Specially significant are active faults within accretionary prisms rooted into overpressured subduction interfaces,and steep reverse faults activated by high overpressures from b.s.z.reservoirs during compressional inversion.展开更多
Because single trigger system is unreliable for shock wave overpressure test, this paper presents a multi-trigger overpressure test system. The large memory capacity is divided into parts to achieve data acquisition a...Because single trigger system is unreliable for shock wave overpressure test, this paper presents a multi-trigger overpressure test system. The large memory capacity is divided into parts to achieve data acquisition and storage with multiple triggers. Compared with conventional single-shot storage test system, this system can prevent false trigger and improve reliability of the test. By using explosion time to extract valid signal segments, it improves the efficiency of data recovery. These characteristics of the system contribute to multi-point test. After the dynamic characteristics of the system are calibrated, the valid data can be obtained in explosion experiments. The results show that the multi-trigger test system has higher reliability than single trigger test system.展开更多
In paper the role of excess pressures in cata- genic processes of the South-Caspian basin (SCB) is considered. The results of the carried out researches taking into account world ex- perience on the given problem allo...In paper the role of excess pressures in cata- genic processes of the South-Caspian basin (SCB) is considered. The results of the carried out researches taking into account world ex- perience on the given problem allow to con- clude, that SCB (mainly its deep-water part), as well as a number of other basins of the world with overpressures, is characterized by retarda- tion of processes cracking of kerogen and oil, and also reaction of transformation of clay minerals. Periodic intensification of these pro- cesses can provoke development of diapirs and mud volcanoes, which are the centers of pulse unloading of a hydrocarbon products from sys- tem. The conclusion about high prospects of revealing of hydrocarbon accumulations in deep buried deposits in overpressured basins is made.展开更多
文摘Growth of ln0.52Al0.48As epitaxial layers on lnP(100) substrates by molecular beam epitaxy at a wide range of arsenic overpressures (V/III flux ratios from 30 to 300) has been carried out. Analysis performed using low-temperature photoluminescence (PL) and double-axis X-ray diffraction (XRD) shows a strong and prominent dependence of the PL and XRD linewidths on the V/III flux ratio. Under our growth conditions, both the PL and XRD linewidths exhibit a minimum point at a V/III flux ratio of 150 which corresponds to a maximum in the PL intensity and XRD intensity ratio. Flux ratios exceeding 150 result in an increase in both the PL and XRD linewidths corresponding to a reduction in their associated intensities. Room temperature Raman scattering measurements show a narrowing in the lnAs-like and AlAs-like longitudinal-optic (LO)phonon linewidths which broaden at high flux ratios, while the LO phonon frequencies exhibit a gradual reduction as the flux ratio is increased. PL spectra taken at increasing temperatures show a quenching of the main emission peak followed by the evolution of a broad lower energy emission which is possibly associated with deep lying centres. This effect is more prominent in samples grown at lower V/III flux ratios. Hall effect measurements show a gradual reduction in the mobility in correspondence to an increase in the electron concentration as the flux ratio is increased.
基金financially supported by National Natural Science Foundation of China(Grant Nos.52378401,52278504)the Fundamental Research Funds for the Central Universities(Grant No.30922010918)。
文摘Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.
基金supported by the National Natural Science Foundation of China(Grant No.U2341269)。
文摘The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personnel from firing artillery within the cab.To investigate the overpressure characteristics of the FFICC,a foreign trade equipment model was used as the research object,and a numerical model was established to analyze the propagation of muzzle blast from the muzzle to the interior of the crew compartment under extreme firing condition.For comparative verification,the muzzle blast experiment included overpressure data from both the flow field outside the crew compartment(FFOCC)and the FFICC,as well as the acceleration data of the crew compartment structure(Str-CC).The research findings demonstrate that the overpressure-time curves of the FFICC exhibit multi-peak characteristics,while the pressure wave shows no significant discontinuity.The enclosed nature of the cab hinders the dissipation of pressure wave energy within the FFICC,leading to sustained high-amplitude overpressure.The frameskin structure helps attenuate the impact of muzzle blast on the FFICC.Conversely,local high overpressure caused by the convex or concave features of the cab's exterior significantly amplifies the overpressure amplitude within the FFICC.
文摘Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accurate overpressure prediction remains challenging in offshore Northwest Borneo despite several decades of drilling experience.This paper focuses on two exploration wells drilled by Brunei Shell Petroleum 40 years apart that faced similar challenges with overpressure prediction and well control.An integrated lookback study is attempted using seismic and well-log data to explore the causes of the unsatisfactory Pore Pressure Prediction(PPP)outcome in pre-drill and real-time operation settings for thesewells.Our study indicates that the misprediction of overpressures is due to real differences in shale pressure(basis of pre-drill work and monitoring)and sand pressure(source of drill kick and well control chal-lenges)due to large-scale vertical leak or expulsion of deep-seated fluids into pre-compacted normally pressured overlying sediments in several regions through a mix of shear and tensile failure mechanisms.Such migrated fluids inflate the sand pressure in the normally compacted shallower sequences with the shale pressure remaining low.A predictive framework for upward fluid expulsion was attempted but found impracticable due to complex spatial and temporal variations in the horizontal stress field responsible for such leakage.As such,it is proposed that these migratory overpressures are essentially'unpredictable'from conventional PPP workflows viewed in the broad bucket of compaction disequi-librium(undercompaction)and fluid expansion(unloading)mechanisms.Further study is recommended to understand if such migrated overpressures in the sand can produce a discernible and predictable geophysical or petrophysical signature in the abutting normally compacted shales.The study highlights the possibility of large lateral variability in the sand overpressure within the same stratigraphic unit in regions with complex tectonostratigraphic evolution like Northwest Borneo.
基金supported by the National Natural Science Foundation of China(Project Approval Number:52404270)Postdoctoral Innovative Talent Support Program(BX20230427)+2 种基金Postdoctoral Surface Fund Grants(2023M743874)Research Start-up Fund of China University of Petroleum(Beijing)(2462023XKBH017)Fundamental Research Project Grant of China Academy of Safety Science and Technology(2023JBKY07)。
文摘Gas explosions are a frequent hazard in underground confined spaces in the process of urban development.Liquid sedimentary layers,commonly present in these environments,have not been sufficiently studied in terms of their impact on explosion dynamics.This study aims to investigate how gas-liquid two-phase environments in confined underground spaces affect the explosion characteristics of natural gas.To achieve this,experiments are conducted to examine the propagation of natural gas explosions in water and diesel layers,focusing on the influence of liquid properties and the liquid fullness degree(Lx)on explosion behavior.The results indicate that the presence of a liquid layer after the initial ignition stage significantly attenuates both the peak overpressure and the rise speed of pressure,in comparison to the natural gas conditions.During the subsequent explosive reaction,the evaporation and combustion of the diesel surface resulted in a distinct double-peak pressure rise profile in the diesel layer,with the second peak notably exceeding the first peak.Under conditions with a liquid sedimentary layer,the flame propagation velocities range from 6.53 to 34.1 m/s,while the overpressure peaks vary between 0.157 and 0.255 MPa.The explosion duration in both the water and diesel layer environments is approximately twice as long as that of the natural gas explosion,although the underlying mechanisms differ.In the diesel layer,the prolonged explosion time is attributed to the evaporation and combustion of the diesel,while in the water layer,the flame propagation velocity is significantly reduced.Under the experimental conditions,the maximum explosion energy reached 7.15×10~6J,corresponding to a TNT equivalent of 1.7.The peak overpressure surpassed the threshold for human fatality as defined by overpressure standards,posing a potential risk of damage to large steel-frame structures.The explosion shockwave in diesel layer conditions(L_(d)=0%,5%,7.5%,12.5%)and water layer(L_(w)=12.5%)conditions is observed to be sufficient to damage earthquake-resistant reinforced concrete.This study investigates the impact of sediment layer thickness and composition on gas explosions,and evaluates the associated explosion energy to assess human injuries and structural damage in underground environments.The findings of this study provide a scientific reference for urban underground safety.
基金funded by the National Natural Science Foundation of China(Grant No. 12302437)Jiangsu Provincial Natural Science Foundation (Grant No.SBK2023045424)。
文摘To explore the design criteria for composite charges and reveal the intrinsic relationship between the detonation wave propagation in composite charges and the overall energy distribution of shock waves,this study analyzes the propagation and interaction processes of detonation waves in composite charges with different structural dimensions and explosive combinations. It also investigates the spatial distribution characteristics of the resulting shock wave loads. Based on dimensional analysis theory, a theoretical analysis of the shock wave overpressure distribution in free air fields is conducted. Utilizing the derived dimensionless function relationships, the hydrocode AUTODYN is employed to investigate the effects of charge structure parameters and explosive combinations on the internal overdriven detonation phenomena and the distribution of shock wave loads. It is found that the overdriven detonation phenomenon in the inner layer of composite charges increases the strength of the axial detonation wave,thereby enhancing the intensity of the primary end wave formed upon refraction into the air, which affects the distribution characteristics of the shock wave overpressure. Research has shown that increasing the thickness ratio and detonation velocity ratio of composite charges is beneficial for exacerbating the phenomenon of overdriven detonation, improving the primary end wave intensity and axial overpressure. This gain effect gradually weakens with the propagation of shock waves. When overdriven detonation occurs inside the composite charge, the detonation pressure first increases and then decreases. The Mach reflection pressure of the composite charge with a larger aspect ratio is attenuated to a greater extent. In addition, as the aspect ratio of the composite charge increases, the shock wave energy gradually flows from the axial direction to the radial direction. Therefore, as the aspect ratio of the composite charge increases, the primary end wave intensity and axial overpressure gradually decrease.
基金supported by Innovative Research Group Project of the National Natural Science Foundation of China(Grant Nos.42072151,42272137 and 42372144)China National Petroleum Corporation(CNPC)Forward-looking Basic and Strategic Technology Research Project(Grant No.2021DJ0205)。
文摘It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure.Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression.However,due to limited degree of exploration,there are some problems in the study area,such as unclear understanding of the origin of overpressure and the vague investigation of overpressure evolution.To clarify the impact of overpressure on oil and gas migration and accumulation in the study area,this study focuses on the research of the origin and evolution of overpressure in the Shahezi Formation of the study area,utilizing single well logging parameters and combining methods such as microthermometry of fluid inclusions,laser Raman spectrum,and basin simulation.The results show that the overpressure of the Shahezi Formation in Xujiaweizi fault depression is primarily generated by hydrocarbon generation pressurization,and the evolution of overpressure is closely related to hydrocarbon generation.The development of overpressure can be divided into two evolutionary stages:early hydrocarbon generation pressurization and late uplift release,with slight variations in different regions.Tight glutenite gas reservoirs in the Shahezi Formation are characterized by continuous charging.The overall charging period ranges from the late Denglouku to the early Mingshui(110-67 Ma ago).There is an obvious paleo-overpressure during the gas reservoir formation period.The gas generation period of source rocks occurred approximately 125-60 Ma ago,and the main gas generation period(112-67 Ma ago)highly coincides with the period of natural gas charging.The anomalously high pressure during the accumulation period is considered the significant driving force for natural gas charging.In addition,the sustained effect of overpressure provides better conditions for the preservation of tight gas reservoirs within the source.The results of the study are of guiding significance for the in-depth exploration and development of deep tight sandstone gas in the Shahezi Formation of Xujiaweizi fault depression.
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The work is supported by the National Science and Technology Major Project of China(No.2016ZX05044,2011ZX05007-004)the National Natural Science Foundation of China(No.41502132).
文摘Much progress in the studies on overpressuring mechanisms has been made during the past one to two decades.(1)The causes of overpressure are divided into five categories,namely,disequilibrium compaction,fluid expansion,diagenesis,tectonic compression and pressure transfer.The fluid expansion involves hydrocarbon generation,oil cracking to gas and hydrothermal expansion.The diagenesis includes smectite-to-illite transformation.(2)Six methods for identifying overpressure origin are proposed,including log curves combination analysis,Bowers method(loading-unloading diagram),velocitydensity crossplotting,correlation of porosities,pressure calculation and correlation,and comprehensive analyses.(3)With more and more application of empirical methods in the study of overpressure formation,almost all of the overpressure cases that are traditionally thought to be caused by disequilibrium compaction are denied totally or partly.Instead,the hydrocarbon generation is demonstrated to be the most significant mechanism for overpressure formation;the clay diagenesis(especially the smectiteillite transformation)as well as tectonic compression and pressure transfer are also important for overpressure formation.In addition,the overpressure formation in many basins is thought to be influenced by the combination of two or more overpressuring mechanisms.(4)Causes of overpressuring differ in lithology;for mudstones,the overpressure formation in source rocks is usually different from that of non-source rocks,the former of which is frequently related to hydrocarbon generation and sometimes also affected by diagenesis,while the later of which is commonly related to disequilibrium compaction,diagenesis and pressure transfer;for permeable rocks such as sandstones,overpressure is mainly caused by pressure transfer.(5)Because organic matter has an obvious influence on logging parameters such as density and acoustic velocity,an appropriate correction on the content of organic matter is needed when these logging data are used to analyze overpressure formation in organic-rich mudstones.It has been revealed that the cause of overpressuring based on the corrected log data can be quite different from that without correction.
基金funded by Key R&D Projects in Hubei Province (Grant No.2020BCA084)Innovative Group Project of Hubei Natural Science Foundation (Grant No.2020CFA043)。
文摘Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in different regions.The above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP program.The results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP waveform.Through dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was obtained.According to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are set.The above results can provide a reference for the design and construction of the reinforced concrete blast wall.
基金the support of the National Natural Science Foundation of China(Grant No.12302440)China Postdoctoral Science Foundation(Grant No.2023M741713)。
文摘As a kind of high-efficiency explosive with compound destructive capability, the energy output law of thermobaric explosives has been receiving great attention. In order to investigate the effects of main components on the explosive characteristics of thermobaric explosives, various high explosives and oxidants were selected to formulate five different types of thermobaric explosive. Then they were tested in both open space and closed space respectively. Pressure measurement system, high-speed camera,infrared thermal imager and multispectral temperature measurement system were used for pressure,temperature and fireball recording. The effects of different components on the explosive characteristics of thermobaric explosive were analyzed. The results showed that in open space, the overpressure is dominated by the high explosives content in the formulation. The addition of the oxidants will decrease the explosion overpressure but will increase the duration and overall brightness of the fireball. While in closed space, the quasi-static pressure formed after the explosion is positively correlated with the temperature and gas production. In addition, it was found that the differences in shell constraints can also alter the afterburning reaction of thermobaric explosives, thus affecting their energy output characteristics. PVC shell constraint obviously increases the overpressure and makes the fireball burn more violently.
基金Supported by the Natural Science Foundation of Hebei(D2024501002)Fundamental Research Funds for the Central Universities(N2423020)Major Science and Technology Projects of CNPC(2021ZZ10)。
文摘Based on the observation and analysis of cores and thin sections,and combined with cathodoluminescence,laser Raman,fluid inclusions,and in-situ LA-ICP-MS U-Pb dating,the genetic mechanism and petroleum geological significance of calcite veins in shales of the Cretaceous Qingshankou Formation in the Songliao Basin were investigated.Macroscopically,the calcite veins are bedding parallel,and show lenticular,S-shaped,cone-in-cone and pinnate structures.Microscopically,they can be divided into syntaxial blocky or columnar calcite veins and antitaxial fibrous calcite veins.The aqueous fluid inclusions in blocky calcite veins have a homogenization temperature of 132.5–145.1℃,the in-situ U-Pb dating age of blocky calcite veins is(69.9±5.2)Ma,suggesting that the middle maturity period of source rocks and the conventional oil formation period in the Qingshankou Formation are the sedimentary period of Mingshui Formation in Late Cretaceous.The aqueous fluid inclusions in fibrous calcite veins with the homogenization temperature of 141.2–157.4℃,yields the U-Pb age of(44.7±6.9)Ma,indicating that the middle-high maturity period of source rocks and the Gulong shale oil formation period in the Qingshankou Formation are the sedimentary period of Paleocene Yi'an Formaiton.The syntaxial blocky or columnar calcite veins were formed sensitively to the diagenetic evolution and hydrocarbon generation,mainly in three stages(fracture opening,vein-forming fluid filling,and vein growth).Tectonic extrusion activities and fluid overpressure are induction factors for the formation of fractures,and vein-forming fluid flows mainly as diffusion in a short distance.These veins generally follow a competitive growth mode.The antitaxial fibrous calcite veins were formed under the driving of the force of crystallization in a non-competitive growth environment.It is considered that the calcite veins in organic-rich shale of the Qingshankou Formation in the study area has important implications for local tectonic activities,fluid overpressure,hydrocarbon generation and expulsion,and diagenesis-hydrocarbon accumulation dating of the Songliao Basin.
基金funded by the National Natural Science Foundation of China(42072187)Heilongjiang Province open competition projects:“Research on the diagenetic dynamic evolution process and its coupling relationship with pores and fractures”(2021ZXJ01A09)。
文摘The enrichment and development of shale oil are significantly influenced by the evolution of clay minerals.In this paper,the mineralogy and clay mineral crystallinity of shale samples from Wells X1,X2 and X3 in the Gulong Sag are characterized by X-ray diffraction analysis(XRD)and field emission scanning electron microscopy(FE-SEM).Geochemical parameters,including total organic carbon(TOC)and rock-eval pyrolysis,were also evaluated.The results reveal that illite in the shale primarily exists in the matrix,originating mainly from the transformation of smectite and I/S mixed layer.Chlorite in pores is predominantly formed through fluid precipitation and crystallization.The study area exhibits abnormal evolution of illite and I/S mixed layers,as well as the phenomenon of rapid chlorite growth under overpressure condition.The abnormal evolution of illite and I/S mixed layer may attribute to the inhibition of the conversion reaction from I/S mixed layer to illite.Chlorite's rapid growth occurs through the nucleation mechanism.Furthermore,through the analysis of clay and organic matter correlation,coupled with overpressure and hydrocarbon-rich section considerations,it is observed that chlorite may play a significant role in the storage and generation of S1.This study contributes to a better understanding of the relationship between clay mineral evolution and shale reservoir overpressure,offering valuable insights for the accurate assessment of shale oil.
基金Supported by the China National Offshore Oil Corporation Project(KJGG2022--0302)。
文摘Based on the data from 3D seismic surveys,drilling,sidewall coring,thin sections,and tests,this paper analyzes Meso-Cenozoic geotectonic dynamics,buried-hill reservoir characteristics,and differential enrichment patterns of oil and gas in the buried hills,as well as case studies of typical reservoirs,to systematically discuss the conditions required for the formation of buried-hills and reservoirs and accumulations in the large oil and gas fields in deep to ultra-deep composite buried hills in the Bohai Sea..The key findings are as follows.First,deep to ultra-deep composite buried hills developed in the offshore Bohai Bay Basin primarily due to the double-episode destruction of the North China Craton in the Yanshanian and Himalayan.The Tanlu Fault's activity and the destruction of the North China Craton worked together to create the destruction center,which moved and converged episodically from the Bohai Bay Basin's margins towards the Bozhong Sag.This led to the formation of two development zones for composite buried hills and an orderly process of mountain-building within the offshore Bohai Bay Basin and subsequently two development zones for composite buried hills,i.e.the middle and inner rim zones within the Bozhong Depression.Second,under the coupling of favorable lithologies and multi-stage structures,the middle and inner rim zones are favorable for the formation of reservoirs in fluid dissolution-pore/fracture zones underlying the weathering crust.Third,Massive hydrocarbons were produced along the middle and inner rim zones during the Episode Ⅱ craton destruction,which caused overpressure.These hydrocarbons then moved to and accumulated in the composite buried hills.Excellent conditions for the accumulation of hydrocarbons are still present in the interior and lower portions of these buried hills.These results encourage a change in buried hill research to investigate composite buried hills in three dimensions.It should be noted that the multi-stage volcanic structures in the inner rim zone of the Sag and the deep to ultra-deep composite buried hill interiors in the middle rim zone are significant successor areas for further Bohai Sea exploration.
基金supported by the National Natural Science Foundation of China(Grant Nos.42172147 and 41972141).
文摘Overpressure is widely developed in deep petroliferous strata in the hinterland of the Junggar Basin.However,a comprehensive understanding of its origin and effect on hydrocarbon distribution and enrichment remains lacking.In this study,we employ five empirical methods and comprehensive geological analysis to identify the origin of overpressure,and uncover the effect of overpressure on hydrocarbon enrichment.The results indicate that disequilibrium compaction is not a significant factor in overpressure generation.Instead,hydrocarbon generation,pressure transfer and diagenesis are the primary causes.The empirical methods support this conclusion.There is a positive correlation between overpressure intensity and source rock thickness and maturity.Notably,widespread cross-formational migration of hydrocarbon bearing fluid occurred,with sandstone overpressure exceeding that of adjacent shale in non-source strata.Furthermore,there is a distinct transformation from smectite to illite near the top of overpressure.Hydrocarbon generation pressurization and pressure transfer significantly effect hydrocarbon enrichment.The overpressure caused by hydrocarbon generation drives hydrocarbon migration and accumulation,establishing an optimal energy configuration between reservoir and cap rock.Faults play a crucial role in hydrocarbon vertical migration and pressure relief.The overpressure in reservoirs can reduce the porosity and permeability thresholds and enhance the charging capacity of oil and gas.
基金financed by the Military University of Technology under research project UGB 2024the Ludwig-Maximilian University of Munich (LMU)。
文摘A direct comparison is made between the effectiveness of Al,Mg,and Be powders as additional fuels in model thermobaric compositions containing 20%fuel,20%ammonium perchlorate,and 60%RDX(1,3,5-Trinitro-1,3,5-triazacyclohexane)passivated with wax.Experimentally determined calorimetric measurements of the heat of detonation,along with the overpressure histories in an explosion chamber filled with nitrogen,were used to determine the quasi-static pressure(QSP)under anaerobic conditions.Overpressure measurements were also performed in a semi-closed bunker,and all blast wave parameters generated after the detonation of 500 g charges of the tested explosives were determined.Detonation calorimetry results,QSP values,and blast wave parameters(pressure amplitude,specific and total impulses)clearly indicate that Be is much more effective as an additional fuel than either Al or Mg in both anaerobic post-detonation reactions as well as the subsequent aerobic combustion.The heat of detonation of the RDXwax/AP/Be explosive mixture is over 40%and 50%higher than that of the mixture containing aluminum and magnesium instead of beryllium,respectively.Moreover,the TNT equivalent of the Be-containing composition due to the overpressure in the nitrogen-filled explosion chamber is 1.66,while the equivalent calculated using an air shock wave-specific impulse at a distance of 2.5 m is equal to 1.69.The high values of these parameters confirm the high reactivity of beryllium in both the anaerobic and aerobic stages of the thermobaric explosion.
文摘The accurate prediction of peak overpressure of explosion shockwaves is significant in fields such as explosion hazard assessment and structural protection, where explosion shockwaves serve as typical destructive elements. Aiming at the problem of insufficient accuracy of the existing physical models for predicting the peak overpressure of ground reflected waves, two physics-informed machine learning models are constructed. The results demonstrate that the machine learning models, which incorporate physical information by predicting the deviation between the physical model and actual values and adding a physical loss term in the loss function, can accurately predict both the training and out-oftraining dataset. Compared to existing physical models, the average relative error in the predicted training domain is reduced from 17.459%-48.588% to 2%, and the proportion of average relative error less than 20% increased from 0% to 59.4% to more than 99%. In addition, the relative average error outside the prediction training set range is reduced from 14.496%-29.389% to 5%, and the proportion of relative average error less than 20% increased from 0% to 71.39% to more than 99%. The inclusion of a physical loss term enforcing monotonicity in the loss function effectively improves the extrapolation performance of machine learning. The findings of this study provide valuable reference for explosion hazard assessment and anti-explosion structural design in various fields.
文摘In quartzo-feldspathic continental crust with moderate-to-high heat flow,seismic activity extends to depths of 10-20 km,bounded by isotherms in the 350-450 C range.Fluid overpressuring above hydrostatic in seismogenic crust,is heterogeneous but tends to develop in the lower seismogenic zone(basal seismogenic zone reservoir=b.s.z.reservoir) where the transition between hydrostatically pressured and overpressured crust is likely an irregular,time-dependent.3-D interface with overpressuring concentrated around active faults and their ductile shear zone roots.The term Arterial Fault is applied to fault structures that root in portions of the crust where pore fluids are overpressured(i.e.at> hydrostatic pressure) and serve as feeders for such fluids and their contained solutes into overlying parts of the crust.While arterial flow may occur on any type of fault,it is most likely to be associated with reverse faults in areas of horizontal compression where fluid overpressuring is most easily sustained.Frictional stability and flow permeability of faults are both affected by the state of stress on the fault(shear stress,τ;normal stress,σn),the level of pore-fluid pressure,Pf,and episodes of fault slip,allowing for a complex interplay between fault movement and fluid flow.For seismically active faults the time dependence of permeability is critical,leading to fault-valve behaviour whereby overpressures accumulate at depth during interseismic intervals with fluid discharged along enhanced fault-fracture permeability following each rupture event.Patterns of mineralization also suggest that flow along faults is non-uniform,concentrating along tortuous pathways within the fault surface.Equivalent hydrostatic head above ground level for near-lithostatic overpressures at depth(<1.65×depth of zone) provides a measure of arterial potential.Settings for arterial faults include fault systems developed in compacting sedimentary basins,faults penetrating zones of active plutonic intrusion that encounter overpressured fluids exsolved from magma,together with those derived from contact metamorphism of fluid-rich wallrocks,and/or from regional devolatilisation accompanying prograde metamorphism.Specially significant are active faults within accretionary prisms rooted into overpressured subduction interfaces,and steep reverse faults activated by high overpressures from b.s.z.reservoirs during compressional inversion.
文摘Because single trigger system is unreliable for shock wave overpressure test, this paper presents a multi-trigger overpressure test system. The large memory capacity is divided into parts to achieve data acquisition and storage with multiple triggers. Compared with conventional single-shot storage test system, this system can prevent false trigger and improve reliability of the test. By using explosion time to extract valid signal segments, it improves the efficiency of data recovery. These characteristics of the system contribute to multi-point test. After the dynamic characteristics of the system are calibrated, the valid data can be obtained in explosion experiments. The results show that the multi-trigger test system has higher reliability than single trigger test system.
文摘In paper the role of excess pressures in cata- genic processes of the South-Caspian basin (SCB) is considered. The results of the carried out researches taking into account world ex- perience on the given problem allow to con- clude, that SCB (mainly its deep-water part), as well as a number of other basins of the world with overpressures, is characterized by retarda- tion of processes cracking of kerogen and oil, and also reaction of transformation of clay minerals. Periodic intensification of these pro- cesses can provoke development of diapirs and mud volcanoes, which are the centers of pulse unloading of a hydrocarbon products from sys- tem. The conclusion about high prospects of revealing of hydrocarbon accumulations in deep buried deposits in overpressured basins is made.
