In this study,a new image-based method for the extraction and characterization of pore-throat network for unconventional hydrocarbon storage and exploitation is proposed.“Pore-throat solidity”,which is analogous to ...In this study,a new image-based method for the extraction and characterization of pore-throat network for unconventional hydrocarbon storage and exploitation is proposed.“Pore-throat solidity”,which is analogous to particle solidity,and a new method for automatic identification of pores and throats in tight sandstone oil reservoirs are introduced.Additionally,the“pore-throat combination”and“pure pore”are defined and distinguished by drawing the cumulative probability curve of the pore-throat solidity and by selecting an appropriate cutoff point.When the discrete grid set is recognized as a pore-throat combination,Legendre ellipse fitting and minimum Feret diameter are used.When the pore and throat grid sets are identified as pure pores,the pore diameter can be directly calculated.Using the new method,the analytical results for the physical parameters and pore radius agree well with most prior studies.The results comparing the maximum ball and the new model could also prove the accuracy of the latter's in micro and nano scales.The new model provides a more practical theoretical basis and a new calculation method for the rapid and accurate evaluation of the complex processes of oil migration.展开更多
A method for in-situ stress measurement via fiber optics was proposed. The method utilizes the relationship between rock mass elastic parameters and in-situ stress. The approach offers the advantage of long-term stres...A method for in-situ stress measurement via fiber optics was proposed. The method utilizes the relationship between rock mass elastic parameters and in-situ stress. The approach offers the advantage of long-term stress measurements with high spatial resolution and frequency, significantly enhancing the ability to measure in-situ stress. The sensing casing, spirally wrapped with fiber optic, is cemented into the formation to establish a formation sensing nerve. Injecting fluid into the casing generates strain disturbance, establishing the relationship between rock mass properties and treatment pressure.Moreover, an optimization algorithm is established to invert the elastic parameters of formation via fiber optic strains. In the first part of this paper series, we established the theoretical basis for the inverse differential strain analysis method for in-situ stress measurement, which was subsequently verified using an analytical model. This paper is the fundamental basis for the inverse differential strain analysis method.展开更多
In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs,three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-p...In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs,three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-pressure core displacement experiments.Fine quantitative characterization of the cores in three steady states(original,after sulfur injection,and after gas flooding)was carried out using the nuclear magnetic resonance(NMR)transverse relaxation time spectrum and imaging,X-ray computer tomography(CT)of full-diameter cores,basic physical property testing,and field emission scanning electron microscopy imaging.The loss of pore volume caused by sulfur deposition and adsorption mainly comes from the medium and large pores with sizes bigger than 1000μm.Liquid sulfur has a stronger adsorption and deposition ability in smaller pore spaces,and causes greater damage to reservoirs with poor original pore structures.The pore structure of the three types of carbonate reservoirs shows multiple fractal characteristics.The worse the pore structure,the greater the change of internal pore distribution caused by liquid sulfur deposition and adsorption,and the stronger the heterogeneity.Liquid sulfur deposition and adsorption change the pore size distribution,pore connectivity,and heterogeneity of the rock,which further changes the physical properties of the reservoir.After sulfur injection and gas flooding,the permeability of TypeⅠreservoirs with good physical properties decreased by 16%,and that of TypesⅡandⅢreservoirs with poor physical properties decreased by 90%or more,suggesting an extremely high damage.This indicates that the worse the initial physical properties,the greater the damage of liquid sulfur deposition and adsorption.Liquid sulfur is adsorbed and deposited in different types of pore space in the forms of flocculence,cobweb,or retinitis,causing different changes in the pore structure and physical property of the reservoir.展开更多
Based on the new data of drilling, seismic, logging, test and experiments, the key scientific problems in reservoir formation, hydrocarbon accumulation and efficient oil and gas development methods of deep and ultra-d...Based on the new data of drilling, seismic, logging, test and experiments, the key scientific problems in reservoir formation, hydrocarbon accumulation and efficient oil and gas development methods of deep and ultra-deep marine carbonate strata in the central and western superimposed basin in China have been continuously studied.(1) The fault-controlled carbonate reservoir and the ancient dolomite reservoir are two important types of reservoirs in the deep and ultra-deep marine carbonates. According to the formation origin, the large-scale fault-controlled reservoir can be further divided into three types:fracture-cavity reservoir formed by tectonic rupture, fault and fluid-controlled reservoir, and shoal and mound reservoir modified by fault and fluid. The Sinian microbial dolomites are developed in the aragonite-dolomite sea. The predominant mound-shoal facies, early dolomitization and dissolution, acidic fluid environment, anhydrite capping and overpressure are the key factors for the formation and preservation of high-quality dolomite reservoirs.(2) The organic-rich shale of the marine carbonate strata in the superimposed basins of central and western China are mainly developed in the sedimentary environments of deep-water shelf of passive continental margin and carbonate ramp. The tectonic-thermal system is the important factor controlling the hydrocarbon phase in deep and ultra-deep reservoirs, and the reformed dynamic field controls oil and gas accumulation and distribution in deep and ultra-deep marine carbonates.(3) During the development of high-sulfur gas fields such as Puguang, sulfur precipitation blocks the wellbore. The application of sulfur solvent combined with coiled tubing has a significant effect on removing sulfur blockage. The integrated technology of dual-medium modeling and numerical simulation based on sedimentary simulation can accurately characterize the spatial distribution and changes of the water invasion front.Afterward, water control strategies for the entire life cycle of gas wells are proposed, including flow rate management, water drainage and plugging.(4) In the development of ultra-deep fault-controlled fractured-cavity reservoirs, well production declines rapidly due to the permeability reduction, which is a consequence of reservoir stress-sensitivity. The rapid phase change in condensate gas reservoir and pressure decline significantly affect the recovery of condensate oil. Innovative development methods such as gravity drive through water and natural gas injection, and natural gas drive through top injection and bottom production for ultra-deep fault-controlled condensate gas reservoirs are proposed. By adopting the hierarchical geological modeling and the fluid-solid-thermal coupled numerical simulation, the accuracy of producing performance prediction in oil and gas reservoirs has been effectively improved.展开更多
Radial well filled with phase change material has been proposed as a novel sand control method for hydrate exploitation.In order to reveal the sand control mechanism,CFD-DEM coupling method is applied to simulate the ...Radial well filled with phase change material has been proposed as a novel sand control method for hydrate exploitation.In order to reveal the sand control mechanism,CFD-DEM coupling method is applied to simulate the migration,settlement,and blockage processes of sand particles in the radial well.The obtained results indicate that three scenarios have been recognized for sand particles passing through sand control medium,based on the diameter ratio of sand control medium to sand particle(D_(d)):fully passing(D_(d)=8.75-22.5),partially passing and partially blocked(D_(d)=3.18-5.63),and completely blocked(D_(d)=2.18-3.21).After being captured by the sand control medium,sand particles can block pores,which increases fluid flow resistance and causes a certain pressure difference in the radial well.The pressure in the radial well should be lower than the hydrate phase equilibrium pressure during sand control design,for the purpose of promoting hydrate decomposition,and sand capture.The length of the radial well should be optimized based on the reservoir pore pressure,production pressure difference,bottom hole pressure,and the pressure gradient in the radial well.It should be noticed that the sand control medium leads to a decrease in permeability after sand particles captured.Even the permeability is reduced to several hundred millidarcy,it is still sufficient to ensure the effective flow of gas and water after hydrate decomposition.Increasing fluid velocity reduces the blocking capacity of the sand control medium,mainly because of deterioration in bridging between sand particles.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
The authors regret<In the post-editing process,we inadvertently omitted a citation for Fig.6,which is a concise schematic representation of image processing.The missing citation is:"Du,S.H.,2019.Prediction of ...The authors regret<In the post-editing process,we inadvertently omitted a citation for Fig.6,which is a concise schematic representation of image processing.The missing citation is:"Du,S.H.,2019.Prediction of permeability and its anisotropy of tight oil reservoir via precise pore-throat tortuosity characterization and'umbrella deconstruction'method.J.Petrol.Sci.Eng.,178,1018-1028.https://doi.org/10.1016/j.petrol.2019.03.009".This does not influence any result or conclusion presented in the article.>The authors would like to apologise for any inconvenience caused.展开更多
Three-dimensional global magnetohydrodynamic simulations of the solar wind-magnetosphere-ionosphere system are carried out to explore the dependence of the magnetospheric reconnection voltage, the ionospheric transpol...Three-dimensional global magnetohydrodynamic simulations of the solar wind-magnetosphere-ionosphere system are carried out to explore the dependence of the magnetospheric reconnection voltage, the ionospheric transpolar potential, and the field aligned currents （FACs） on the solar wind driver and ionosphere load for the cases with pure southward interplanetary magnetic field （IMF）. It is shown that the reconnection voltage and the transpolar potential increase monotonically with decreasing Pedersen conductance （∑ p ）, increasing southward IMF strength （Bs） and solar wind speed （Vsw）. Moreover, both regions 1 and 2 FACs increase when Bs and vsw increase, whereas the two currents behave differently in response to ∑p. As ∑p increases, the region 1 FAC increases monotonically, but region 2 FAC shows a non-monotonic response to the increase of ∑p ： it first increases in the range of （0,5） Siemens and then decreases for ∑p 〉 5 Siemens.展开更多
We construct a realistic model to evaluate the chorus wave-particle interaction in the outer radiation belt L = 4.5. This model incorporates a plasmatrough number density model, a field-aligned density model and a rea...We construct a realistic model to evaluate the chorus wave-particle interaction in the outer radiation belt L = 4.5. This model incorporates a plasmatrough number density model, a field-aligned density model and a realistic wave power and frequency model. We solve the 2D bounce-averaged momentum-pitch-angle Fokker-Planck equation and show that the Whistler-mode chorus can be effective in the acceleration of electrons, and enhance the phase space density for energies of -1 MeV by a factor from 10 to 10^3 in about two days, consistent with the observation. We also demonstrate that ignorance of the electron number density variation along field line and magnetic local time in the previous work yields an overestimate of energetic electron phase space density by a factor 5-10 at large pitch-angle after two days, suggesting that a realistic plasma density model is very important to evaluate the evolution of energetic electrons in the outer radiation belt.展开更多
A three-dimensional magnetohydrodynamics （MHD） code is designed specially for global simulations of the solar wind-magnetosphere-ionosphere system. The code possesses a high resolution in capturing MHD shocks and di...A three-dimensional magnetohydrodynamics （MHD） code is designed specially for global simulations of the solar wind-magnetosphere-ionosphere system. The code possesses a high resolution in capturing MHD shocks and discontinuities and a low numerical dissipation in examining possible instabilities inherent in the system. The ionosphere is approximated by a spherical shell with uniform height-integrated conductance. The solar wind is steady, and the interplanetary magnetic field is either due northward or due southward. The code is then run to find solutions of the whole system. It is found that the system has never reached a steady state, but keeps oscillating with a period of about one hour in terms of density variation at the geosynchronous orbit. However, if a certain artificial resistivity is added either in the whole numerical box or in the reconnection sites only, the reconnections change from intermittent to steady regime and the oscillation disappears accordingly. We conclude that the Earth＇s magnetosphere tends to be in a ceaseless oscillation status because of the low dissipation property inherent in the magnetospheric plasma, and the oscillation may be driven by intermittent magnetic reconnections that occur somewhere in the magnetopause and/or the magnetotail.展开更多
A multi-dimensional electron phase-space hole （electron hole） is considered to be unstable to the transverse instability. We perform two-dimensional （2D） particle-in-cell （PIC） simulations to study the evolution...A multi-dimensional electron phase-space hole （electron hole） is considered to be unstable to the transverse instability. We perform two-dimensional （2D） particle-in-cell （PIC） simulations to study the evolutions of electron holes in weakly magnetized plasma （Ωe〈 Wpe, where Ωe and Wpe are the electron gyrofrequency and plasma frequency, respectively）, and the effects of perpendicular thermal velocities on the transverse instability are investigated. The transverse instability can cause decay of the electron holes. We find that with the increasing perpendicular thermal velocity tending to stabilize the transverse instability, the corresponding wave numbers decrease.展开更多
Carbon neutrality(or climate neutrality)has been a global consensus,and international experience exchange is essential.Given the differences in the degree of social development,resource endowment and technological lev...Carbon neutrality(or climate neutrality)has been a global consensus,and international experience exchange is essential.Given the differences in the degree of social development,resource endowment and technological level,each country should build a carbon-neutral plan based on its national conditions.Compared with other major developed countries(e.g.,Germany,the United States and Japan),China's carbon neutrality has much bigger challenges,including a heavy and time-pressured carbon reduction task and the current energy structure that is over-dependent on fossil fuels.Here we provide a comprehensive review of the status and prospects of the key technologies for low-carbon,near-zero carbon,and negative carbon emissions.Technological innovations associated with coal,oil-gas and hydrogen industries and their future potential in reducing carbon emissions are particularly explained and assessed.Based on integrated analysis of international experience from the world's major developed countries,in-depth knowledge of the current and future technologies,and China's energy and ecological resources potential,five lessons for the implementation of China's carbon neutrality are proposed:(1)transformation of energy production pattern from a coal-dominated pattern to a diversified renewable energy pattern;(2)renewable power-to-X and large-scale underground energy storage;(3)integration of green hydrogen production,storage,transport and utilization;(4)construction of clean energy systems based on smart sector coupling(ENSYSCO);(5)improvement of ecosystem carbon sinks both in nationwide forest land and potential desert in Northwest China.This paper provides an international perspective for a better understanding of the challenges and opportunities of carbon neutrality in China,and can serve as a theoretical foundation for medium-long term carbon neutral policy formulation.展开更多
Hydrocarbon expulsion features and resource potential evaluation of source rocks are crucial for the petroleum exploration.High-maturity marine source rocks have not exhibited a hydrocarbon expulsion mode owing to the...Hydrocarbon expulsion features and resource potential evaluation of source rocks are crucial for the petroleum exploration.High-maturity marine source rocks have not exhibited a hydrocarbon expulsion mode owing to the lack of low-maturity source rocks in deep petroliferous basins.We considered the Ediacaran microbial dolomite in the Sichuan Basin,the largest high-maturity marine gas layer in China,to exhibit a method that quantitatively characterizes the hydrocarbon expulsion of high-maturity marine source rocks.The experiment of fluid inclusion,rock pyrolysis,and vitrinite reflectance(Ro)of 119 microbial dolomite core samples obtained from the Dengying Formation were performed.A hydrocarbon expulsion model of high-maturity source rock was established,and its resource potential was evaluated.The results showed that the Ediacaran microbial dolomite in the Sichuan Basin is a good source rock showing vast resource potential.The hydrocarbon expulsion threshold is determined to be vitrinite reflectance at 0.92%.The hydrocarbon expulsion intensities in the geologic history is high with maximum of 1.6×10^(7)t/km^(2).The Ediacaran microbial dolomite expelled approximately 1.008×10^(12)t of hydrocarbons,and the recoverable resource was 1.5×10^(12)m^(3).The region can be categorized into areasⅠ,Ⅱ,Ⅲ,andⅣ,in decreasing order of hydrocarbon expulsion intensity.Areas with a higher hydrocarbon expulsion intensity have a lower drilling risk and should be prioritized for exploration in the orderⅠ>Ⅱ>Ⅲ>Ⅳ.Two areas,northern and central parts of Ediacaran in the Sichuan Basin,were selected as prospects which had the drilling priority in the future gas exploration.The production data of 55 drilled wells verified the high reliability of this method.This model in this study does not require low-maturity samples and can be used for evaluating high-maturity marine source rocks,which has broad applicability in deep basins worldwide.展开更多
In the past 15 years,the shale gas revolution and large-scale commercial developments in the United States have driven the exploration and development of shale plays worldwide.Among many factors affecting shale gas ex...In the past 15 years,the shale gas revolution and large-scale commercial developments in the United States have driven the exploration and development of shale plays worldwide.Among many factors affecting shale gas exploration potential,the gas-bearing properties of shale(quantity,storage state,composition)and their controlling factors are the essential research attracting wide attention in the academic community.This paper reviews the research progress on the retention mechanism,influencing factors,and evaluation methods for resource potential of the shale gas system,and proposes further research directions.Sorption is the main mechanism of gas retention in organic-rich shales;the gas is mainly stored in nanopores of shale in free and sorption states.The presence of water and nonhydrocarbon gases in pores can complicate the process and mechanism of methane(CH4)sorption,and the related theoretical models still need further development.The in-situ gas content and gasbearing properties of shale are governed by the geological properties(organic matter abundance,kerogen type,thermal maturity,mineral composition,diagenesis),the properties of fluids in pores(water,CH_(4),non-hydrocarbon gases),and geological conditions(temperature,pressure,preservation conditions)of the shale itself.For a particular basin or block,it is still challenging to define the main controlling factors,screen favorable exploration areas,and locate sweet spots.Compared to marine shales with extensive research and exploration data,lacustrine and marine-continental transitional shales are a further expanding area of investigation.Various methods have been developed to quantitatively characterize the in-situ gas content of shales,but all these methods have their own limitations,and more in-depth studies are needed to accurately evaluate and predict the in-situ gas content of shales,especially shales at deep depth.展开更多
Xin’anbian Oilfield of the Ordos Basin is the large tight oilfield to be first exploration discovery in china.The production of tight oil increased significantly in recent years.It shows great exploration potential o...Xin’anbian Oilfield of the Ordos Basin is the large tight oilfield to be first exploration discovery in china.The production of tight oil increased significantly in recent years.It shows great exploration potential of Chang 7 tight oil.But the physical property and hydrocarbon enrichment characteristics of Chang 7 tight oil reservoirs were rarely studied,The forming conditions of tight oil reservoirs are systematically summarized and analyzed through the study of hydrocarbon generation,sedimentary reservoirs and hydrocarbon migration and accumulation based on production and core experimental data.The result shows that,The porosity of the Chang 7_(2)reservoir mainly distributed in 5.0-11.0%,average at 7.9%,The permeability mainly distributed in 0.04-0.18×10^(-3)μm^(2),average at 0.12×10^(-3)μm^(2),The pore diameters of the tight oil reservoir distributed in 2-8μm.The high-quality Chang 7_(3)source rocks and the micropsammite of Chang 7_(2)subaqueous distributary channel were widely distributed in the study area.The lenticular or banded sand bodies are distributed among mudstone or hydrocarbon source rocks and have the advantage of migration distance for hydrocarbon accumulation.The reservoir space is composed of micro-nanometer pores and throat,that is formed in the process of increasing pressure during hydrocarbon generation and hydrocarbon accumulation.The Chang 7 tight oil was generated in the early Cretaceous and injected into the sand of the subaqueous distributary channel driven by continuous hydrocarbon generation supercharging.The formation and accumulation of tight oil reservoirs are mainly controlled by source rocks,sedimentary microfacies and reservoirs of good quality.展开更多
The Solar Polar ORbit Telescope(SPORT) project for space weather mission has been under intensive scientific and engineering background studies since it was incorporated into the Chinese Space Science Strategic Pionee...The Solar Polar ORbit Telescope(SPORT) project for space weather mission has been under intensive scientific and engineering background studies since it was incorporated into the Chinese Space Science Strategic Pioneer Project in 2011.SPORT is designed to carry a suite of remote-sensing and in-situ instruments to observe Coronal Mass Ejections(CMEs),energetic particles,solar high-latitude magnetism,and the fast solar wind from a polar orbit around the Sun.The first extended view of the polar regions of the Sun and the ecliptic enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere,and the solar high-latitude magnetism giving rise to eruptions and the fast solar wind.Coordinated observations between SPORT and other spaceborne/ground-based facilities within the International Living With a Star(ILWS) framework can significantly enhance scientific output.SPORT is now competing for official selection and implementation during China's 13 th Five-Year Plan period of 2016-2020.展开更多
In order to investigate the impact of U-ore on organic matter maturation and isotopic fractionation,we designed hydrous pyrolysis experiments on Type-II kerogen samples,supposing that the water and water–mineral inte...In order to investigate the impact of U-ore on organic matter maturation and isotopic fractionation,we designed hydrous pyrolysis experiments on Type-II kerogen samples,supposing that the water and water–mineral interaction play a role.U-ore was set as the variable for comparison.Meanwhile,anhydrous pyrolysis under the same conditions was carried out as the control experiments.The determination of liquid products indicates that the presence of water and minerals obviously enhanced the yields of C（15＋） and the amounts of hydrocarbon and nonhydrocarbon gases.Such results may be attributed to waterorganic matter reaction in the high-temperature system,which can provide additional hydrogen and oxygen for the generation of gas and liquid products from organic matter.It is found that δD values of hydrocarbon gases generated in both hydrous pyrolysis experiments are much lower than those in anhydrous pyrolysis.What is more,δD values are lower in the hydrous pyrolysis with uranium ore.Therefore,we can infer that water-derived hydrogen played a significant role during the kerogen thermal evolution and the hydrocarbon generation in our experiments.Isotopic exchange was facilitated by the reversible equilibration between reaction intermediaries with hydrogen under hydrothermal conditions with uranium ore.Carbon isotopic fractionations of hydrocarbon gases were somehow affected by the presence of water and the uranium ore.The increased level of i-C4/n-C4ratios for gas products in hydrous pyrolysis implied the carbocation mechanism for water-kerogen reactions.展开更多
Hydraulic fracturing is a critical technology for the economic development of unconventional oil and gas reservoirs.The main factor influencing fracture propping and reservoir stimulation effect is proppant performanc...Hydraulic fracturing is a critical technology for the economic development of unconventional oil and gas reservoirs.The main factor influencing fracture propping and reservoir stimulation effect is proppant performance.The increasing depth of fractured oil and gas reservoirs is causing growing difficulty in hydraulic fracturing.Moreover,the migration of conventional proppants within the fracture is always limited due to small fracture width and rigid proppant structure.Thus,proppants with good transportation capacity and fracture propping effects are needed.First,a novel self-generated proppant based on toughened low-viscosity and low-density epoxy resin was developed to satisfy this demand.Then,proppant performances were evaluated.Low-viscosity and low-density epoxy resin was generated when the thiol-ene click chemical reaction product of eugenol and 1-thioglycerol reacts with the epichlorohydrin.Then,the resin was toughened with graphite particles to increase its compressive strength from50.8 to 72.1 MPa based on micro-cracking mechanism and crazing-nail anchor mechanism.The adduct of diethylene triamine and butyl glycidyl ether and the Si O2 nanoparticles were treated as the curing agent and emulsifier respectively to form the emulsion.The emulsion is transformed into solid particles of various sizes within a reservoir to prop the fracture.Evaluation shows good migration capacity of this self-generated proppant due to the low density of epoxy resin.展开更多
Taking the Jurassic Sangonghe Formation in the Mosuowan-Mobei area of the Junggar Basin as an example, this paper provides a method that evaluates paleo hydrocarbon pools and predicts secondary reservoirs. Through Qua...Taking the Jurassic Sangonghe Formation in the Mosuowan-Mobei area of the Junggar Basin as an example, this paper provides a method that evaluates paleo hydrocarbon pools and predicts secondary reservoirs. Through Quantitative Grain Fluorescence （QGF） experiments, well-tie seismic correlation, and paleo structure analysis, the scale and distribution of paleo hydrocarbon pools in the study area are outlined. Combining current structural features and fault characteristics, the re-migration pathways of paleo oil and gas are depicted. Based on barrier conditions on the oil re-migration pathways and current reservoir distribution, we recognize three types of secondary reservoirs. By analyzing structural evolution and sand body-fault distribution, the major control factors of secondary reservoirs are specified and, consequently, favorable zones for secondary reservoirs are predicted. The results are mainly as follows. （1） In the primary accumulation period in the Cretaceous, paleo hydrocarbon pools were formed in the Sangonghe Formation of the Mosuowan uplift and their size and distribution were extensive and the exploration potential for secondary reservoirs should not be ignored. Besides, paleo reservoirs were also formed in the Mobei uplift, but just small scale. （2） In the adjustment period in the Neogene, traps were reshaped or destroyed and so were the paleo reservoirs, resulting in oil release. The released oil migrated linearly northward along the structural highs of the Mobei uplift and the Qianshao low-relief uplift and then formed secondary reservoirs when it met new traps. In this process, a structural ridge cooperated with sand bodies and faults, applying unobstructed pathways for oil and gas re-migration. （3） The secondary hydrocarbon pools are classified into three types： low-relief anticlinal type, lithologic pinch-out type and fault block type. The distribution of the first type is controlled by a residual low uplift in the north flank of the paleo-anticline. The second type is distributed in the lithologic pinch-out zones on the periphery of the inherited paleo uplift. The third type is controlled by fault zones of which the strikes are perpendicular to the hydrocarbon re-migration pathways. （4） Four favorable zones for secondary reservoirs are predicted： the low-relief structural zone of the north flank of the Mosuowan paleo-anticline, the fault barrier zone on the western flank of the Mobei uplift, the Qianshao low-relief uplift and the north area of the Mobei uplift that parallels the fault zone. The study above effectively supports the exploration of the Qianshao low-relief uplift, with commercial oil discovered in the Qianshaol well. Besides, the research process in this paper can also be applied to other basins to explore for secondary reservoirs.展开更多
Taking the Paleogene salt strata in the west of Kuqa foreland thrust belt as study object, the deformation features of salt structure in the compression direction and perpendicular to the compression direction were ex...Taking the Paleogene salt strata in the west of Kuqa foreland thrust belt as study object, the deformation features of salt structure in the compression direction and perpendicular to the compression direction were examined to find out the control factors and formation mechanisms of the salt structures. By using the three-dimensional discrete element numerical simulation method, the formation mechanisms of typical salt structures of western Kuqa foreland thrust belt in Keshen and Dabei work areas were comprehensively analyzed. The simulation results show that the salt deformation in Keshen and Dabei work areas is of forward spread type, with deformation concentrated in the piedmont zone;the salt deformation is affected by the early uplift near the compression end, pre-existing basement faults, synsedimentary process and the initial salt depocenter;in the direction perpendicular to the compression direction, salt rocks near the compression end have strong lateral mobility with the velocity component moving towards the middle part, and the closer to the middle, the larger the velocity will be, so that salt rocks will aggregate towards the middle and deform intensely, forming complex folds and separation of salt structures from salt source, and local outcrop with thrust faults. Compared with 2 D simulation, 3 D simulation can analyze salt structures in the principal stress direction and direction perpendicular to the principal stress, give us a full view of the formation mechanisms of salt structures, and guide the exploration of oil and gas reservoirs related to salt structures.展开更多
基金jointly supported by Beijing Natural Science Foundation(No.8232054)Young Elite Scientists Sponsorship Program by CAST(No.YESS20220094)+2 种基金Young Elite Scientists Sponsorship Program by BAST(No.BYESS2023182)Youth Innovation Promotion Association CAS(No.2023021)National Natural Science Foundation of China(No.41902132)。
文摘In this study,a new image-based method for the extraction and characterization of pore-throat network for unconventional hydrocarbon storage and exploitation is proposed.“Pore-throat solidity”,which is analogous to particle solidity,and a new method for automatic identification of pores and throats in tight sandstone oil reservoirs are introduced.Additionally,the“pore-throat combination”and“pure pore”are defined and distinguished by drawing the cumulative probability curve of the pore-throat solidity and by selecting an appropriate cutoff point.When the discrete grid set is recognized as a pore-throat combination,Legendre ellipse fitting and minimum Feret diameter are used.When the pore and throat grid sets are identified as pure pores,the pore diameter can be directly calculated.Using the new method,the analytical results for the physical parameters and pore radius agree well with most prior studies.The results comparing the maximum ball and the new model could also prove the accuracy of the latter's in micro and nano scales.The new model provides a more practical theoretical basis and a new calculation method for the rapid and accurate evaluation of the complex processes of oil migration.
基金the Project Support of NSFC(No.U19B6003-05 and No.52074314)。
文摘A method for in-situ stress measurement via fiber optics was proposed. The method utilizes the relationship between rock mass elastic parameters and in-situ stress. The approach offers the advantage of long-term stress measurements with high spatial resolution and frequency, significantly enhancing the ability to measure in-situ stress. The sensing casing, spirally wrapped with fiber optic, is cemented into the formation to establish a formation sensing nerve. Injecting fluid into the casing generates strain disturbance, establishing the relationship between rock mass properties and treatment pressure.Moreover, an optimization algorithm is established to invert the elastic parameters of formation via fiber optic strains. In the first part of this paper series, we established the theoretical basis for the inverse differential strain analysis method for in-situ stress measurement, which was subsequently verified using an analytical model. This paper is the fundamental basis for the inverse differential strain analysis method.
基金Supported by the National Natural Science Foundation of China(U19B6003)Sinopec Technology Research Project(P20077kxjgz)。
文摘In order to clarify the influence of liquid sulfur deposition and adsorption to high-H2S gas reservoirs,three types of natural cores with typical carbonate pore structures were selected for high-temperature and high-pressure core displacement experiments.Fine quantitative characterization of the cores in three steady states(original,after sulfur injection,and after gas flooding)was carried out using the nuclear magnetic resonance(NMR)transverse relaxation time spectrum and imaging,X-ray computer tomography(CT)of full-diameter cores,basic physical property testing,and field emission scanning electron microscopy imaging.The loss of pore volume caused by sulfur deposition and adsorption mainly comes from the medium and large pores with sizes bigger than 1000μm.Liquid sulfur has a stronger adsorption and deposition ability in smaller pore spaces,and causes greater damage to reservoirs with poor original pore structures.The pore structure of the three types of carbonate reservoirs shows multiple fractal characteristics.The worse the pore structure,the greater the change of internal pore distribution caused by liquid sulfur deposition and adsorption,and the stronger the heterogeneity.Liquid sulfur deposition and adsorption change the pore size distribution,pore connectivity,and heterogeneity of the rock,which further changes the physical properties of the reservoir.After sulfur injection and gas flooding,the permeability of TypeⅠreservoirs with good physical properties decreased by 16%,and that of TypesⅡandⅢreservoirs with poor physical properties decreased by 90%or more,suggesting an extremely high damage.This indicates that the worse the initial physical properties,the greater the damage of liquid sulfur deposition and adsorption.Liquid sulfur is adsorbed and deposited in different types of pore space in the forms of flocculence,cobweb,or retinitis,causing different changes in the pore structure and physical property of the reservoir.
基金Supported by the National Natural Science Foundation of ChinaCorporate Innovative Development Joint Fund(U19B6003)。
文摘Based on the new data of drilling, seismic, logging, test and experiments, the key scientific problems in reservoir formation, hydrocarbon accumulation and efficient oil and gas development methods of deep and ultra-deep marine carbonate strata in the central and western superimposed basin in China have been continuously studied.(1) The fault-controlled carbonate reservoir and the ancient dolomite reservoir are two important types of reservoirs in the deep and ultra-deep marine carbonates. According to the formation origin, the large-scale fault-controlled reservoir can be further divided into three types:fracture-cavity reservoir formed by tectonic rupture, fault and fluid-controlled reservoir, and shoal and mound reservoir modified by fault and fluid. The Sinian microbial dolomites are developed in the aragonite-dolomite sea. The predominant mound-shoal facies, early dolomitization and dissolution, acidic fluid environment, anhydrite capping and overpressure are the key factors for the formation and preservation of high-quality dolomite reservoirs.(2) The organic-rich shale of the marine carbonate strata in the superimposed basins of central and western China are mainly developed in the sedimentary environments of deep-water shelf of passive continental margin and carbonate ramp. The tectonic-thermal system is the important factor controlling the hydrocarbon phase in deep and ultra-deep reservoirs, and the reformed dynamic field controls oil and gas accumulation and distribution in deep and ultra-deep marine carbonates.(3) During the development of high-sulfur gas fields such as Puguang, sulfur precipitation blocks the wellbore. The application of sulfur solvent combined with coiled tubing has a significant effect on removing sulfur blockage. The integrated technology of dual-medium modeling and numerical simulation based on sedimentary simulation can accurately characterize the spatial distribution and changes of the water invasion front.Afterward, water control strategies for the entire life cycle of gas wells are proposed, including flow rate management, water drainage and plugging.(4) In the development of ultra-deep fault-controlled fractured-cavity reservoirs, well production declines rapidly due to the permeability reduction, which is a consequence of reservoir stress-sensitivity. The rapid phase change in condensate gas reservoir and pressure decline significantly affect the recovery of condensate oil. Innovative development methods such as gravity drive through water and natural gas injection, and natural gas drive through top injection and bottom production for ultra-deep fault-controlled condensate gas reservoirs are proposed. By adopting the hierarchical geological modeling and the fluid-solid-thermal coupled numerical simulation, the accuracy of producing performance prediction in oil and gas reservoirs has been effectively improved.
基金sponsored by National Natural Science Foundation of China (Grand No.52204024,52074332)CNPC Innovation Found (Grant No.2021DQ02-1006)Fundamental Research Funds for the Central Universities (No.2-9-2023-049)。
文摘Radial well filled with phase change material has been proposed as a novel sand control method for hydrate exploitation.In order to reveal the sand control mechanism,CFD-DEM coupling method is applied to simulate the migration,settlement,and blockage processes of sand particles in the radial well.The obtained results indicate that three scenarios have been recognized for sand particles passing through sand control medium,based on the diameter ratio of sand control medium to sand particle(D_(d)):fully passing(D_(d)=8.75-22.5),partially passing and partially blocked(D_(d)=3.18-5.63),and completely blocked(D_(d)=2.18-3.21).After being captured by the sand control medium,sand particles can block pores,which increases fluid flow resistance and causes a certain pressure difference in the radial well.The pressure in the radial well should be lower than the hydrate phase equilibrium pressure during sand control design,for the purpose of promoting hydrate decomposition,and sand capture.The length of the radial well should be optimized based on the reservoir pore pressure,production pressure difference,bottom hole pressure,and the pressure gradient in the radial well.It should be noticed that the sand control medium leads to a decrease in permeability after sand particles captured.Even the permeability is reduced to several hundred millidarcy,it is still sufficient to ensure the effective flow of gas and water after hydrate decomposition.Increasing fluid velocity reduces the blocking capacity of the sand control medium,mainly because of deterioration in bridging between sand particles.
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.
文摘The authors regret<In the post-editing process,we inadvertently omitted a citation for Fig.6,which is a concise schematic representation of image processing.The missing citation is:"Du,S.H.,2019.Prediction of permeability and its anisotropy of tight oil reservoir via precise pore-throat tortuosity characterization and'umbrella deconstruction'method.J.Petrol.Sci.Eng.,178,1018-1028.https://doi.org/10.1016/j.petrol.2019.03.009".This does not influence any result or conclusion presented in the article.>The authors would like to apologise for any inconvenience caused.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40831060, 40621003 and 40774077, the China Postdoctoral Science Foundation （20070420725）, and K. C. Wong Education Foundation of Hong Kong.
文摘Three-dimensional global magnetohydrodynamic simulations of the solar wind-magnetosphere-ionosphere system are carried out to explore the dependence of the magnetospheric reconnection voltage, the ionospheric transpolar potential, and the field aligned currents （FACs） on the solar wind driver and ionosphere load for the cases with pure southward interplanetary magnetic field （IMF）. It is shown that the reconnection voltage and the transpolar potential increase monotonically with decreasing Pedersen conductance （∑ p ）, increasing southward IMF strength （Bs） and solar wind speed （Vsw）. Moreover, both regions 1 and 2 FACs increase when Bs and vsw increase, whereas the two currents behave differently in response to ∑p. As ∑p increases, the region 1 FAC increases monotonically, but region 2 FAC shows a non-monotonic response to the increase of ∑p ： it first increases in the range of （0,5） Siemens and then decreases for ∑p 〉 5 Siemens.
基金Supported by the National Natural Science Foundation of China Grant Nos 40774077, 40774078 and 40874076, the National Key Basic Research Special Foundation of China Grant No 2006CB806304, and the Chinese Academy of Sciences under Grant No KZCX3-SW- 144.
文摘We construct a realistic model to evaluate the chorus wave-particle interaction in the outer radiation belt L = 4.5. This model incorporates a plasmatrough number density model, a field-aligned density model and a realistic wave power and frequency model. We solve the 2D bounce-averaged momentum-pitch-angle Fokker-Planck equation and show that the Whistler-mode chorus can be effective in the acceleration of electrons, and enhance the phase space density for energies of -1 MeV by a factor from 10 to 10^3 in about two days, consistent with the observation. We also demonstrate that ignorance of the electron number density variation along field line and magnetic local time in the previous work yields an overestimate of energetic electron phase space density by a factor 5-10 at large pitch-angle after two days, suggesting that a realistic plasma density model is very important to evaluate the evolution of energetic electrons in the outer radiation belt.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40474053 and 40325010.
文摘A three-dimensional magnetohydrodynamics （MHD） code is designed specially for global simulations of the solar wind-magnetosphere-ionosphere system. The code possesses a high resolution in capturing MHD shocks and discontinuities and a low numerical dissipation in examining possible instabilities inherent in the system. The ionosphere is approximated by a spherical shell with uniform height-integrated conductance. The solar wind is steady, and the interplanetary magnetic field is either due northward or due southward. The code is then run to find solutions of the whole system. It is found that the system has never reached a steady state, but keeps oscillating with a period of about one hour in terms of density variation at the geosynchronous orbit. However, if a certain artificial resistivity is added either in the whole numerical box or in the reconnection sites only, the reconnections change from intermittent to steady regime and the oscillation disappears accordingly. We conclude that the Earth＇s magnetosphere tends to be in a ceaseless oscillation status because of the low dissipation property inherent in the magnetospheric plasma, and the oscillation may be driven by intermittent magnetic reconnections that occur somewhere in the magnetopause and/or the magnetotail.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40974081, 40971053 and 40725013, the Knowledge Innovation Project of Chinese Academy of Sciences under Grant No KJCX2-YW-N28, and the Specialized Research Fund for State Key Laboratories.
文摘A multi-dimensional electron phase-space hole （electron hole） is considered to be unstable to the transverse instability. We perform two-dimensional （2D） particle-in-cell （PIC） simulations to study the evolutions of electron holes in weakly magnetized plasma （Ωe〈 Wpe, where Ωe and Wpe are the electron gyrofrequency and plasma frequency, respectively）, and the effects of perpendicular thermal velocities on the transverse instability are investigated. The transverse instability can cause decay of the electron holes. We find that with the increasing perpendicular thermal velocity tending to stabilize the transverse instability, the corresponding wave numbers decrease.
基金supported by the Henan Institute for Chinese Development Strategy of Engineering&Technology(Grant No.2022HENZDA02)by the Science&Technology Department of Sichuan Province Project(Grant No.2021YFH0010).
文摘Carbon neutrality(or climate neutrality)has been a global consensus,and international experience exchange is essential.Given the differences in the degree of social development,resource endowment and technological level,each country should build a carbon-neutral plan based on its national conditions.Compared with other major developed countries(e.g.,Germany,the United States and Japan),China's carbon neutrality has much bigger challenges,including a heavy and time-pressured carbon reduction task and the current energy structure that is over-dependent on fossil fuels.Here we provide a comprehensive review of the status and prospects of the key technologies for low-carbon,near-zero carbon,and negative carbon emissions.Technological innovations associated with coal,oil-gas and hydrogen industries and their future potential in reducing carbon emissions are particularly explained and assessed.Based on integrated analysis of international experience from the world's major developed countries,in-depth knowledge of the current and future technologies,and China's energy and ecological resources potential,five lessons for the implementation of China's carbon neutrality are proposed:(1)transformation of energy production pattern from a coal-dominated pattern to a diversified renewable energy pattern;(2)renewable power-to-X and large-scale underground energy storage;(3)integration of green hydrogen production,storage,transport and utilization;(4)construction of clean energy systems based on smart sector coupling(ENSYSCO);(5)improvement of ecosystem carbon sinks both in nationwide forest land and potential desert in Northwest China.This paper provides an international perspective for a better understanding of the challenges and opportunities of carbon neutrality in China,and can serve as a theoretical foundation for medium-long term carbon neutral policy formulation.
基金supported by the Open Fund Project of State Key Laboratory of Lithospheric Evolution [SKL-K202103]support of the Exploration and Development Research Institute of Petro China Southwest Oil & Gas Field
文摘Hydrocarbon expulsion features and resource potential evaluation of source rocks are crucial for the petroleum exploration.High-maturity marine source rocks have not exhibited a hydrocarbon expulsion mode owing to the lack of low-maturity source rocks in deep petroliferous basins.We considered the Ediacaran microbial dolomite in the Sichuan Basin,the largest high-maturity marine gas layer in China,to exhibit a method that quantitatively characterizes the hydrocarbon expulsion of high-maturity marine source rocks.The experiment of fluid inclusion,rock pyrolysis,and vitrinite reflectance(Ro)of 119 microbial dolomite core samples obtained from the Dengying Formation were performed.A hydrocarbon expulsion model of high-maturity source rock was established,and its resource potential was evaluated.The results showed that the Ediacaran microbial dolomite in the Sichuan Basin is a good source rock showing vast resource potential.The hydrocarbon expulsion threshold is determined to be vitrinite reflectance at 0.92%.The hydrocarbon expulsion intensities in the geologic history is high with maximum of 1.6×10^(7)t/km^(2).The Ediacaran microbial dolomite expelled approximately 1.008×10^(12)t of hydrocarbons,and the recoverable resource was 1.5×10^(12)m^(3).The region can be categorized into areasⅠ,Ⅱ,Ⅲ,andⅣ,in decreasing order of hydrocarbon expulsion intensity.Areas with a higher hydrocarbon expulsion intensity have a lower drilling risk and should be prioritized for exploration in the orderⅠ>Ⅱ>Ⅲ>Ⅳ.Two areas,northern and central parts of Ediacaran in the Sichuan Basin,were selected as prospects which had the drilling priority in the future gas exploration.The production data of 55 drilled wells verified the high reliability of this method.This model in this study does not require low-maturity samples and can be used for evaluating high-maturity marine source rocks,which has broad applicability in deep basins worldwide.
基金supported by the National Natural Science Foundation of China(U19B6003-03-01)the Science and Technology Department of Shanxi Province,China(20201101003)the National Natural Science Foundation of China(42030804).
文摘In the past 15 years,the shale gas revolution and large-scale commercial developments in the United States have driven the exploration and development of shale plays worldwide.Among many factors affecting shale gas exploration potential,the gas-bearing properties of shale(quantity,storage state,composition)and their controlling factors are the essential research attracting wide attention in the academic community.This paper reviews the research progress on the retention mechanism,influencing factors,and evaluation methods for resource potential of the shale gas system,and proposes further research directions.Sorption is the main mechanism of gas retention in organic-rich shales;the gas is mainly stored in nanopores of shale in free and sorption states.The presence of water and nonhydrocarbon gases in pores can complicate the process and mechanism of methane(CH4)sorption,and the related theoretical models still need further development.The in-situ gas content and gasbearing properties of shale are governed by the geological properties(organic matter abundance,kerogen type,thermal maturity,mineral composition,diagenesis),the properties of fluids in pores(water,CH_(4),non-hydrocarbon gases),and geological conditions(temperature,pressure,preservation conditions)of the shale itself.For a particular basin or block,it is still challenging to define the main controlling factors,screen favorable exploration areas,and locate sweet spots.Compared to marine shales with extensive research and exploration data,lacustrine and marine-continental transitional shales are a further expanding area of investigation.Various methods have been developed to quantitatively characterize the in-situ gas content of shales,but all these methods have their own limitations,and more in-depth studies are needed to accurately evaluate and predict the in-situ gas content of shales,especially shales at deep depth.
基金financially supported by the Chinese National Special Plan Project"Formation conditions,enrichment regularity and resource potential of tight oil”(No.2016ZX05046-001)。
文摘Xin’anbian Oilfield of the Ordos Basin is the large tight oilfield to be first exploration discovery in china.The production of tight oil increased significantly in recent years.It shows great exploration potential of Chang 7 tight oil.But the physical property and hydrocarbon enrichment characteristics of Chang 7 tight oil reservoirs were rarely studied,The forming conditions of tight oil reservoirs are systematically summarized and analyzed through the study of hydrocarbon generation,sedimentary reservoirs and hydrocarbon migration and accumulation based on production and core experimental data.The result shows that,The porosity of the Chang 7_(2)reservoir mainly distributed in 5.0-11.0%,average at 7.9%,The permeability mainly distributed in 0.04-0.18×10^(-3)μm^(2),average at 0.12×10^(-3)μm^(2),The pore diameters of the tight oil reservoir distributed in 2-8μm.The high-quality Chang 7_(3)source rocks and the micropsammite of Chang 7_(2)subaqueous distributary channel were widely distributed in the study area.The lenticular or banded sand bodies are distributed among mudstone or hydrocarbon source rocks and have the advantage of migration distance for hydrocarbon accumulation.The reservoir space is composed of micro-nanometer pores and throat,that is formed in the process of increasing pressure during hydrocarbon generation and hydrocarbon accumulation.The Chang 7 tight oil was generated in the early Cretaceous and injected into the sand of the subaqueous distributary channel driven by continuous hydrocarbon generation supercharging.The formation and accumulation of tight oil reservoirs are mainly controlled by source rocks,sedimentary microfacies and reservoirs of good quality.
基金Supported by the Strategic Priority Research Program on Space Science(XDA04060801,XDA04060802,XDA04060803,XDA04060804)of Chinese Academy of Sciencesthe Specialized Research Fund for State Key Laboratory of China+1 种基金the Chinese National Science Foundation(41374175,41204129)the CAS/SAFEA international Partnership Program for Creative Research Teams
文摘The Solar Polar ORbit Telescope(SPORT) project for space weather mission has been under intensive scientific and engineering background studies since it was incorporated into the Chinese Space Science Strategic Pioneer Project in 2011.SPORT is designed to carry a suite of remote-sensing and in-situ instruments to observe Coronal Mass Ejections(CMEs),energetic particles,solar high-latitude magnetism,and the fast solar wind from a polar orbit around the Sun.The first extended view of the polar regions of the Sun and the ecliptic enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere,and the solar high-latitude magnetism giving rise to eruptions and the fast solar wind.Coordinated observations between SPORT and other spaceborne/ground-based facilities within the International Living With a Star(ILWS) framework can significantly enhance scientific output.SPORT is now competing for official selection and implementation during China's 13 th Five-Year Plan period of 2016-2020.
文摘In order to investigate the impact of U-ore on organic matter maturation and isotopic fractionation,we designed hydrous pyrolysis experiments on Type-II kerogen samples,supposing that the water and water–mineral interaction play a role.U-ore was set as the variable for comparison.Meanwhile,anhydrous pyrolysis under the same conditions was carried out as the control experiments.The determination of liquid products indicates that the presence of water and minerals obviously enhanced the yields of C（15＋） and the amounts of hydrocarbon and nonhydrocarbon gases.Such results may be attributed to waterorganic matter reaction in the high-temperature system,which can provide additional hydrogen and oxygen for the generation of gas and liquid products from organic matter.It is found that δD values of hydrocarbon gases generated in both hydrous pyrolysis experiments are much lower than those in anhydrous pyrolysis.What is more,δD values are lower in the hydrous pyrolysis with uranium ore.Therefore,we can infer that water-derived hydrogen played a significant role during the kerogen thermal evolution and the hydrocarbon generation in our experiments.Isotopic exchange was facilitated by the reversible equilibration between reaction intermediaries with hydrogen under hydrothermal conditions with uranium ore.Carbon isotopic fractionations of hydrocarbon gases were somehow affected by the presence of water and the uranium ore.The increased level of i-C4/n-C4ratios for gas products in hydrous pyrolysis implied the carbocation mechanism for water-kerogen reactions.
基金financial support of the National Natural Science Foundation of China(Grant No.52074332)express their gratitude to project ZR2020YQ36 supported by Shandong Provincial Science Fund for Excellent Young Scholars+1 种基金the Major Scientific and Technological Projects of CNPC under Grand ZD 2019-184-002-003CNPC Innovation Found(Grant No.2021DQ02-1006)。
文摘Hydraulic fracturing is a critical technology for the economic development of unconventional oil and gas reservoirs.The main factor influencing fracture propping and reservoir stimulation effect is proppant performance.The increasing depth of fractured oil and gas reservoirs is causing growing difficulty in hydraulic fracturing.Moreover,the migration of conventional proppants within the fracture is always limited due to small fracture width and rigid proppant structure.Thus,proppants with good transportation capacity and fracture propping effects are needed.First,a novel self-generated proppant based on toughened low-viscosity and low-density epoxy resin was developed to satisfy this demand.Then,proppant performances were evaluated.Low-viscosity and low-density epoxy resin was generated when the thiol-ene click chemical reaction product of eugenol and 1-thioglycerol reacts with the epichlorohydrin.Then,the resin was toughened with graphite particles to increase its compressive strength from50.8 to 72.1 MPa based on micro-cracking mechanism and crazing-nail anchor mechanism.The adduct of diethylene triamine and butyl glycidyl ether and the Si O2 nanoparticles were treated as the curing agent and emulsifier respectively to form the emulsion.The emulsion is transformed into solid particles of various sizes within a reservoir to prop the fracture.Evaluation shows good migration capacity of this self-generated proppant due to the low density of epoxy resin.
基金supported by the National Science and Technology Major Project(Grant No.2016ZX05046-001)the Petroleum Science Research and Technology Development Project,Petro China(Grant No.2016B-0301)
文摘Taking the Jurassic Sangonghe Formation in the Mosuowan-Mobei area of the Junggar Basin as an example, this paper provides a method that evaluates paleo hydrocarbon pools and predicts secondary reservoirs. Through Quantitative Grain Fluorescence （QGF） experiments, well-tie seismic correlation, and paleo structure analysis, the scale and distribution of paleo hydrocarbon pools in the study area are outlined. Combining current structural features and fault characteristics, the re-migration pathways of paleo oil and gas are depicted. Based on barrier conditions on the oil re-migration pathways and current reservoir distribution, we recognize three types of secondary reservoirs. By analyzing structural evolution and sand body-fault distribution, the major control factors of secondary reservoirs are specified and, consequently, favorable zones for secondary reservoirs are predicted. The results are mainly as follows. （1） In the primary accumulation period in the Cretaceous, paleo hydrocarbon pools were formed in the Sangonghe Formation of the Mosuowan uplift and their size and distribution were extensive and the exploration potential for secondary reservoirs should not be ignored. Besides, paleo reservoirs were also formed in the Mobei uplift, but just small scale. （2） In the adjustment period in the Neogene, traps were reshaped or destroyed and so were the paleo reservoirs, resulting in oil release. The released oil migrated linearly northward along the structural highs of the Mobei uplift and the Qianshao low-relief uplift and then formed secondary reservoirs when it met new traps. In this process, a structural ridge cooperated with sand bodies and faults, applying unobstructed pathways for oil and gas re-migration. （3） The secondary hydrocarbon pools are classified into three types： low-relief anticlinal type, lithologic pinch-out type and fault block type. The distribution of the first type is controlled by a residual low uplift in the north flank of the paleo-anticline. The second type is distributed in the lithologic pinch-out zones on the periphery of the inherited paleo uplift. The third type is controlled by fault zones of which the strikes are perpendicular to the hydrocarbon re-migration pathways. （4） Four favorable zones for secondary reservoirs are predicted： the low-relief structural zone of the north flank of the Mosuowan paleo-anticline, the fault barrier zone on the western flank of the Mobei uplift, the Qianshao low-relief uplift and the north area of the Mobei uplift that parallels the fault zone. The study above effectively supports the exploration of the Qianshao low-relief uplift, with commercial oil discovered in the Qianshaol well. Besides, the research process in this paper can also be applied to other basins to explore for secondary reservoirs.
基金Supported by the China National Science and Technology Major Project(2016ZX05033002,2016ZX05033001).
文摘Taking the Paleogene salt strata in the west of Kuqa foreland thrust belt as study object, the deformation features of salt structure in the compression direction and perpendicular to the compression direction were examined to find out the control factors and formation mechanisms of the salt structures. By using the three-dimensional discrete element numerical simulation method, the formation mechanisms of typical salt structures of western Kuqa foreland thrust belt in Keshen and Dabei work areas were comprehensively analyzed. The simulation results show that the salt deformation in Keshen and Dabei work areas is of forward spread type, with deformation concentrated in the piedmont zone;the salt deformation is affected by the early uplift near the compression end, pre-existing basement faults, synsedimentary process and the initial salt depocenter;in the direction perpendicular to the compression direction, salt rocks near the compression end have strong lateral mobility with the velocity component moving towards the middle part, and the closer to the middle, the larger the velocity will be, so that salt rocks will aggregate towards the middle and deform intensely, forming complex folds and separation of salt structures from salt source, and local outcrop with thrust faults. Compared with 2 D simulation, 3 D simulation can analyze salt structures in the principal stress direction and direction perpendicular to the principal stress, give us a full view of the formation mechanisms of salt structures, and guide the exploration of oil and gas reservoirs related to salt structures.
