Objective Oil-source faults have an important effect on reservoir formation and distribution in shallow formations with non- hydrocarbon generation in oil-rich fault-related basins （Jiang Youlu et al., 2015）. Howev...Objective Oil-source faults have an important effect on reservoir formation and distribution in shallow formations with non- hydrocarbon generation in oil-rich fault-related basins （Jiang Youlu et al., 2015）. However, the fault transporting capacity cannot be evaluated quantitatively at present. Taking the Zhanhua Sag in the Bohai Bay Basin as an example, this work analyzed the factors influencing the transporting capacity of the oil-source faults and proposed a quantitative method for evaluating their transporting capacity.展开更多
Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc....Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and networks like this. The voltage unbalances, for the tested cases in the CIGRE LV test network are mainly due to single phase loads and due to unbalanced faults. The compensation of unbalanced voltage sags and voltage unbalance in the CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0.展开更多
More than 40 years have been passed since exploration and development of oil-gas began in the Bohai Bay Basin. Though we have faced with many difficulties during our exploration, exciting discoveries in petroleum-rich...More than 40 years have been passed since exploration and development of oil-gas began in the Bohai Bay Basin. Though we have faced with many difficulties during our exploration, exciting discoveries in petroleum-rich sags have been made in recent years. Studies show that the petroleumrich sags are characterized by multiple sets of oil-gas accumulation in the pre-Eogene to Neogene strata in profile and large-area connection or superimposition of oil-gas reservoirs in different strata. Therefore, petroleum-rich sags continue to be a focus of future oil-gas exploration in the Bohai Bay Basin. There is still a great potential of petroleum resources. Inshore and offshore areas, onshore stratigraphic reservoirs, high-precision exploration in old oilfields, reservoirs inside buried hills, and volcanic reservoirs will contribute a lot in increasing the annual oil-gas production and reserves in the basin.展开更多
In this study, the differences in reservoir parameters, such as pore radius, throat radius, and pore-throat ratio, between the east and west subsags of the Lishui Sag are analyzed by using data obtained from a constan...In this study, the differences in reservoir parameters, such as pore radius, throat radius, and pore-throat ratio, between the east and west subsags of the Lishui Sag are analyzed by using data obtained from a constant-rate mercury injection experiment. Furthermore, the quality of the reservoirs in the two subsags is systematically evaluated. Results show that the throat radius of the Lishui west subsag is larger than that of the east subsag, and this parameter has a positive correlation with reservoir quality. However, the pore-throat ratio of the east subsag is larger than that of the west subsag, which has an inverse relationship with reservoir quality. The main reasons for this reservoir difference can be attributed to sedimentation and diagenesis. The sedimentary facies types of the Lishui east subsag are the fan delta, shore lake, shallow lake, and shore shallow lake;their sandstone composition maturity is low;the clay mineral content is high;and the rock has undergone strong diagenesis. Therefore, the physical conditions of the reservoir are poor. However, the sandstones in the Lishui west subsag have weak cementation and compaction, mainly with an intergranular pore structure type, which leads to good connectivity between pores. Therefore, the storage performance and seepage capacity of the Lishui west subsag are better than those of the east subsag;the west subsag is the main area of oil and gas accumulation, as confirmed in the process of exploration and development.展开更多
Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.Th...Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.The study shows that the Central African Rift System mainly develops high-quality lacustrine source rocks in the Lower Cretaceous,and the West African Rift System mainly develops high-quality terrigenous organic matter-rich marine source rocks in the Upper Cretaceous,and the two types of source rocks provide a material basis for the enrichment of oil and gas in the CWARS.Multiple sets of reservoir rocks including fractured basement and three sets of regional cap rocks in the Lower Cretaceous,the Upper Cretaceous,and the Paleogene are developed in the CWARS.Since the Late Mesozoic,due to the geodynamic factors including the dextral strike-slip movement of the Central African Shear Zone,the basins in different directions of the CWARS differ in terms of rifting stages,intervals of regional cap rocks,trap types and accumulation models.The NE-SW trending basins have mainly preserved one stage of rifting in the Early Cretaceous,with regional cap rocks developed in the Lower Cretaceous strata,forming traps of reverse anticlines,flower-shaped structures and basement buried hill,and two types of hydrocarbon accumulation models of"source and reservoir in the same formation,and accumulation inside source rocks"and"up-source and down-reservoir,and accumulation below source rocks".The NW–SE basins are characterized by multiple rifting stages superimposition,with the development of regional cap rocks in the Upper Cretaceous and Paleogene,forming traps of draping anticlines,faulted anticlines,antithetic fault blocks and the accumulation model of"down-source and up-reservoir,and accumulation above source rocks".The combination of reservoir and cap rocks inside source rocks of basins with multiple superimposed rifting stages,as well as the lithologic reservoirs and the shale oil inside source rocks of strong inversion basins are important fields for future exploration in basins of the CWARS.展开更多
Notable differences in the structural characteristics and evolution of three adjacent sub-sags,i.e.,the Wenchang sub-sags A,B,and C,on the downthrown side of the Zhu IlI South Fault in the Wenchang Sag,are significant...Notable differences in the structural characteristics and evolution of three adjacent sub-sags,i.e.,the Wenchang sub-sags A,B,and C,on the downthrown side of the Zhu IlI South Fault in the Wenchang Sag,are significant as they affect the formation and distribution of the oil and gas in these three sub-sags.However,the differences in their tectonic evolutions and formation mechanisms have not yet been adequately explained.In this paper,stress analysis,equilibrium profiles,and paleogeomorphic restora-tion,are used to investigate the dynamic settings,formation mechanisms,and influencing factors of the structural deformation related to the formation of the Wenchang Sag based on interpretation of seismic data.The results of the stress analysis suggest clockwise deflection of the regional tensile stress direction from a WNW-ESE trend during the Early Paleocene to NW-SE and NNW-SSE trends during the Eocene,to a nearly N-S trend during the Oligocene,and finally to a NNE-SSW trend during the Miocene.This clockwise rotation of the regional tensile stress direction led to the formation of a dextral strike-slip stress component parallel to the NE-trending Zhu I South Fault.This strike-slip stress component formed a releasing bend in sub-sag A,and may be associated with the continuous subsidence of a thick sedimentary layer in sub-sag A.It also created a restraining bend in sub-sag B,which underwent multiple structural inversions during its extension and subsidence and has a relatively s mall sedimentary thick-ness.The double restraining bend in sub-sag C is considered to have been strongly uplifted and eroded in response to this strike-slip stress component.Four obvious structural inversions in sub-sag B are iden-tified in this paper.These structural inversions correspond to the last four regional tectonic movements.This interpretation suggests that the formation of the structural inversions was likely related to the strong tensile stress and the small intersection angle between the direction of the regional tensile stress and the pre-existing boundary fault.The rotation of the tensile stress direction was responsible for the strike-slip movement on the pre-existing boundary fault and the formation of the releasing bend and restraining bend,which controlled the structural evolutions of the sub-sags.This reasonably explains the differential tectonic evolution of these three sub-sags in the Wenchang Sag,and provides a crucial idea forstructuralanalysisof similarbasins.展开更多
Pearl River Mouth Basin undergoes complex tectonic evolution processes and forms lacustrine,transitional and marine sediments.Drilling shows that there exist large petroleum reserves in the hydrocarbon-rich sags of Pe...Pearl River Mouth Basin undergoes complex tectonic evolution processes and forms lacustrine,transitional and marine sediments.Drilling shows that there exist large petroleum reserves in the hydrocarbon-rich sags of Pearl River Mouth Basin,South China Sea.To reduce the risk,the exploration,structural and sedimentary characteristics of the hydrocarbon-rich sags should be identified and described.Drilling,seismic,and microfossil data are integrated to interpret the structural and sedimentary evolution of the hydrocarbon-rich sags in Pearl River Mouth Basin.By analyzing the tectonic and sedimentary evolutionary characteristics,three conclusions may be drawn:1、The present regional tectonic characteristics of the PRMB are formed by mutual interactions of the Eurasian Plate,Pacific Plate,Philippine Plate and Indian Plate.During the Paleocene to early Eocene and late Eocene and early Oligocene,the PRMB is at the rifting stage.During the late Oligocene,the PRMB was at the rifting-depression transitional stage.After the Oligocene,the PRMB is at the depression stage.2、Tectonic conditions control the sedimentation process in the hydrocarbon-rich sags.During the lacustrine sedimentation stage,synsedimentary faults and intense faulting control the sedimentation.During the transitional sedimentation stage,weak fault activity influences the deposition process in the hydrocarbon-rich sags.During the marine sedimentation stage,weak fault activity and depression activity control the deposition process in the hydrocarbon-rich sags.3、Tectonic evolution affects the deposition process.The lacustrine,transitional and marine sedimentation corresponds to different tectonic conditions.The lacustrine sedimentation is formed under fault activity during the rifting stage.The transitional sedimentation is formed under weak fault activity during the late rifting stage.The marine sedimentation is formed under weak fault activity and depression activity during the rifting-depression and depression stages.4、The half graben is beneficial for the formation of lacustrine source rocks,which is responsible for the hydrocarbon-rich sag.Therefore the half graben mode contributes to the hydrocarbon-rich sags.展开更多
Voltage sages are classified in seven types that in each type, the voltage amplitude and angle of phase voltages are different. We demonstrated that voltage sag types have different effects on synchronous motor, espec...Voltage sages are classified in seven types that in each type, the voltage amplitude and angle of phase voltages are different. We demonstrated that voltage sag types have different effects on synchronous motor, especially on its torque pulsations. Torque pulsations are different in shape of oscillations and moreover, peak torque when voltage magnitude is restored has different correlation with sag duration, as sag type varies. By flux trajectory analysis, we mathematically extracted the critical durations for different types of voltage sags, in the case that the sag begins at the zero angle of the voltage wave. In order to observe the validity of the results, we simulated a synchronous motor subjected to different types of voltage sags. The simulation results confirmed the claim.展开更多
Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control s...Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage sags.To overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is proposed.Based on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive power.And the injected currents are kept within safety values for a better utilization of the VSG power capacity.Furthermore,the experimental platform is built.Experimental results demonstrate the validness and effectiveness of the proposed control strategy.展开更多
Pressure fields of different sags in a petroliferous basin were significantly different,and it was related to hydrocarbon enrichment.Based on pressure data of different sags in Bohai Bay Basin,types of pressure field ...Pressure fields of different sags in a petroliferous basin were significantly different,and it was related to hydrocarbon enrichment.Based on pressure data of different sags in Bohai Bay Basin,types of pressure field and its distribution characteristics were well discussed,and relationships between overpressure and hydrocarbon generation,pressure field and hydrocarbon enrichment were also investigated.Results showed that the Paleogene pressure fields of different sags in Bohai Bay Basin could be divided into three types:normal pressure type,single overpressure type and double overpressure type.These three types of pressure fields had the zoned features in their distributions.The normal pressure fields were mostly distributed in peripheral sags of the basin,while the single overpressure fields were widespread in the basin,and the double overpressure fields were concentrated in the areas around the Bohai Sea.Hydrocarbon generation had a significant effect on overpressure formation,thus overpressure horizons generally were corresponded to major source rock horizons,and differences of filling evolution history and main hydrocarbon-generation strata of different sags might be important factors for the formation of these three types of pressure fields.Overpressure in source rock horizons was closely related to hydrocarbon enrichment.Horizontally,hydrocarbons were mainly distributed around the overpressure center,and the secondary migration distance of hydrocarbons was affected by the degree of overpressure.Vertically,hydrocarbon distributionwas controlled by the type of pressure fields.Hydrocarbons in the normal pressure sags were mainly enriched in the major hydrocarbon-generation horizons and their adjacent horizons,hydrocarbons in the single overpressure sags were mainly distributed in the hydrocarbon-generation horizons and its upper and lower horizons,while in the double overpressure sags,the hydrocarbon enrichment degree in Neogene was high.Hydrocarbon enrichment in sags was controlled by the degree of overpressure in hydrocarbon-generation horizons,and these oil-rich sags had relatively large overpressure degree.展开更多
In practice,an equilibrium point of the power system is considered transiently secure if it can withstand a specified contingency by maintaining transient evolution of rotor angles and voltage magnitudes within set bo...In practice,an equilibrium point of the power system is considered transiently secure if it can withstand a specified contingency by maintaining transient evolution of rotor angles and voltage magnitudes within set bounds.A novel sequential approach is proposed to obtain transiently stable equilibrium points through the preventive control of transient stability and transient voltage sag(TVS)problems caused by a severe disturbance.The proposed approach conducts a sequence of non-heuristic optimal active power re-dispatch of the generators to steer the system toward a transiently secure operating point by sequentially solving the transient-stability-constrained optimal power flow(TSC-OPF)problems.In the proposed approach,there are two sequential projection stages,with the first stage ensuring the rotor angle stability and the second stage removing TVS in voltage magnitudes.In both projection stages,the projection operation corresponds to the TSC-OPF,with its formulation directly derived by adding only two steady-state variable-based transient constraints to the conventional OPF problem.The effectiveness of this approach is numerically demonstrated in terms of its accuracy and computational performance by using the Western System Coordinated Council(WSCC)3-machine 9-bus system and an equivalent model of the Mexican 46-machine 190-bus system.展开更多
Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity.Previous research has demonstrated that hydrogen peroxide(H_(2)O_(2)),specifical...Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity.Previous research has demonstrated that hydrogen peroxide(H_(2)O_(2)),specifically H_(2)O_(2)derived from roots and mediated by the respiratory burst oxidase homolog(NADPH),plays a significant role in regulating ion and plant hormone homeostasis in glycophytic plants,such as Arabidopsis.However,the extent to which root-derived H_(2)O_(2)fulfils similar functions in halophytic plants remains uncertain.Therefore,our study aimed to explore the potential contribution of root-sourced H_(2)O_(2)in delaying leaf senescence induced by high salinity,utilizing seashore paspalum as a model halophytic plant.The application of the NADPH-oxidase inhibitor DPI,coupled with a series of leaf senescence analyses,we revealed that root-derived H_(2)O_(2)significantly retards salt-induced leaf senescence.Furthermore,through the application of hormone analysis,lipidomics,ionomics,Non-invasive Micro-test Technology(NMT),and transcriptomics,we established that NADPH-dependent H_(2)O_(2)induced by salt stress in the roots was indispensable for maintaining the balance of the aging hormone,jasmonic acid(JA),and sodium ion homeostasis within this halophytic plant.Finally,by utilizing AtrbohD Arabidopsis mutants and virus-induced gene silencing(VIGs)in Paspalum vaginatum,we demonstrated the pivotal role played by root-sourced H_(2)O_(2)in upholding JA homeostasis and regulating JA-triggered leaf senescence in P.vaginatum.This study offers novel insights into the mechanisms that govern plant leaf senescence and its response to salinity-induced stress.展开更多
Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and developm...Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.展开更多
基金granted by the National Natural Science Foundation of China(grant No.41672131)Fundamental Research Funds for the Central Universities(grant No.16CX06045A)
文摘Objective Oil-source faults have an important effect on reservoir formation and distribution in shallow formations with non- hydrocarbon generation in oil-rich fault-related basins （Jiang Youlu et al., 2015）. However, the fault transporting capacity cannot be evaluated quantitatively at present. Taking the Zhanhua Sag in the Bohai Bay Basin as an example, this work analyzed the factors influencing the transporting capacity of the oil-source faults and proposed a quantitative method for evaluating their transporting capacity.
文摘Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and networks like this. The voltage unbalances, for the tested cases in the CIGRE LV test network are mainly due to single phase loads and due to unbalanced faults. The compensation of unbalanced voltage sags and voltage unbalance in the CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0.
文摘More than 40 years have been passed since exploration and development of oil-gas began in the Bohai Bay Basin. Though we have faced with many difficulties during our exploration, exciting discoveries in petroleum-rich sags have been made in recent years. Studies show that the petroleumrich sags are characterized by multiple sets of oil-gas accumulation in the pre-Eogene to Neogene strata in profile and large-area connection or superimposition of oil-gas reservoirs in different strata. Therefore, petroleum-rich sags continue to be a focus of future oil-gas exploration in the Bohai Bay Basin. There is still a great potential of petroleum resources. Inshore and offshore areas, onshore stratigraphic reservoirs, high-precision exploration in old oilfields, reservoirs inside buried hills, and volcanic reservoirs will contribute a lot in increasing the annual oil-gas production and reserves in the basin.
基金supported by the National Natural Science Foundation of China (Nos. 51504143 and 51674156)the SDUST Research Fund (No. 2015DJH101)the Major National R&D Projects of China (No. 2016ZX0 5027-001-006)。
文摘In this study, the differences in reservoir parameters, such as pore radius, throat radius, and pore-throat ratio, between the east and west subsags of the Lishui Sag are analyzed by using data obtained from a constant-rate mercury injection experiment. Furthermore, the quality of the reservoirs in the two subsags is systematically evaluated. Results show that the throat radius of the Lishui west subsag is larger than that of the east subsag, and this parameter has a positive correlation with reservoir quality. However, the pore-throat ratio of the east subsag is larger than that of the west subsag, which has an inverse relationship with reservoir quality. The main reasons for this reservoir difference can be attributed to sedimentation and diagenesis. The sedimentary facies types of the Lishui east subsag are the fan delta, shore lake, shallow lake, and shore shallow lake;their sandstone composition maturity is low;the clay mineral content is high;and the rock has undergone strong diagenesis. Therefore, the physical conditions of the reservoir are poor. However, the sandstones in the Lishui west subsag have weak cementation and compaction, mainly with an intergranular pore structure type, which leads to good connectivity between pores. Therefore, the storage performance and seepage capacity of the Lishui west subsag are better than those of the east subsag;the west subsag is the main area of oil and gas accumulation, as confirmed in the process of exploration and development.
基金Supported by the National Natural Science Foundation Project(92255302)National Science and Technology Major Project(2016ZX05029005)Scientific Research and Technological Development Project of PetroChina(2021DJ31).
文摘Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.The study shows that the Central African Rift System mainly develops high-quality lacustrine source rocks in the Lower Cretaceous,and the West African Rift System mainly develops high-quality terrigenous organic matter-rich marine source rocks in the Upper Cretaceous,and the two types of source rocks provide a material basis for the enrichment of oil and gas in the CWARS.Multiple sets of reservoir rocks including fractured basement and three sets of regional cap rocks in the Lower Cretaceous,the Upper Cretaceous,and the Paleogene are developed in the CWARS.Since the Late Mesozoic,due to the geodynamic factors including the dextral strike-slip movement of the Central African Shear Zone,the basins in different directions of the CWARS differ in terms of rifting stages,intervals of regional cap rocks,trap types and accumulation models.The NE-SW trending basins have mainly preserved one stage of rifting in the Early Cretaceous,with regional cap rocks developed in the Lower Cretaceous strata,forming traps of reverse anticlines,flower-shaped structures and basement buried hill,and two types of hydrocarbon accumulation models of"source and reservoir in the same formation,and accumulation inside source rocks"and"up-source and down-reservoir,and accumulation below source rocks".The NW–SE basins are characterized by multiple rifting stages superimposition,with the development of regional cap rocks in the Upper Cretaceous and Paleogene,forming traps of draping anticlines,faulted anticlines,antithetic fault blocks and the accumulation model of"down-source and up-reservoir,and accumulation above source rocks".The combination of reservoir and cap rocks inside source rocks of basins with multiple superimposed rifting stages,as well as the lithologic reservoirs and the shale oil inside source rocks of strong inversion basins are important fields for future exploration in basins of the CWARS.
基金supported by the National Natural Science Foundation of China(Grant No.9132820142006068)Shandong Special Fund of Qingdao National Laboratory of Marine Science and Technology(No.2021QNLM020001-1).
文摘Notable differences in the structural characteristics and evolution of three adjacent sub-sags,i.e.,the Wenchang sub-sags A,B,and C,on the downthrown side of the Zhu IlI South Fault in the Wenchang Sag,are significant as they affect the formation and distribution of the oil and gas in these three sub-sags.However,the differences in their tectonic evolutions and formation mechanisms have not yet been adequately explained.In this paper,stress analysis,equilibrium profiles,and paleogeomorphic restora-tion,are used to investigate the dynamic settings,formation mechanisms,and influencing factors of the structural deformation related to the formation of the Wenchang Sag based on interpretation of seismic data.The results of the stress analysis suggest clockwise deflection of the regional tensile stress direction from a WNW-ESE trend during the Early Paleocene to NW-SE and NNW-SSE trends during the Eocene,to a nearly N-S trend during the Oligocene,and finally to a NNE-SSW trend during the Miocene.This clockwise rotation of the regional tensile stress direction led to the formation of a dextral strike-slip stress component parallel to the NE-trending Zhu I South Fault.This strike-slip stress component formed a releasing bend in sub-sag A,and may be associated with the continuous subsidence of a thick sedimentary layer in sub-sag A.It also created a restraining bend in sub-sag B,which underwent multiple structural inversions during its extension and subsidence and has a relatively s mall sedimentary thick-ness.The double restraining bend in sub-sag C is considered to have been strongly uplifted and eroded in response to this strike-slip stress component.Four obvious structural inversions in sub-sag B are iden-tified in this paper.These structural inversions correspond to the last four regional tectonic movements.This interpretation suggests that the formation of the structural inversions was likely related to the strong tensile stress and the small intersection angle between the direction of the regional tensile stress and the pre-existing boundary fault.The rotation of the tensile stress direction was responsible for the strike-slip movement on the pre-existing boundary fault and the formation of the releasing bend and restraining bend,which controlled the structural evolutions of the sub-sags.This reasonably explains the differential tectonic evolution of these three sub-sags in the Wenchang Sag,and provides a crucial idea forstructuralanalysisof similarbasins.
基金the National Natural Science Foundation of China(No.41702135)the Yangtze Youth Fund(No.2015qq33),the 13th“Five-year”plan of the Ministry of Science and Technology of China(No.2016ZX05037-002)National Science and Technology Major Project(NO.2016ZX05015-006).
文摘Pearl River Mouth Basin undergoes complex tectonic evolution processes and forms lacustrine,transitional and marine sediments.Drilling shows that there exist large petroleum reserves in the hydrocarbon-rich sags of Pearl River Mouth Basin,South China Sea.To reduce the risk,the exploration,structural and sedimentary characteristics of the hydrocarbon-rich sags should be identified and described.Drilling,seismic,and microfossil data are integrated to interpret the structural and sedimentary evolution of the hydrocarbon-rich sags in Pearl River Mouth Basin.By analyzing the tectonic and sedimentary evolutionary characteristics,three conclusions may be drawn:1、The present regional tectonic characteristics of the PRMB are formed by mutual interactions of the Eurasian Plate,Pacific Plate,Philippine Plate and Indian Plate.During the Paleocene to early Eocene and late Eocene and early Oligocene,the PRMB is at the rifting stage.During the late Oligocene,the PRMB was at the rifting-depression transitional stage.After the Oligocene,the PRMB is at the depression stage.2、Tectonic conditions control the sedimentation process in the hydrocarbon-rich sags.During the lacustrine sedimentation stage,synsedimentary faults and intense faulting control the sedimentation.During the transitional sedimentation stage,weak fault activity influences the deposition process in the hydrocarbon-rich sags.During the marine sedimentation stage,weak fault activity and depression activity control the deposition process in the hydrocarbon-rich sags.3、Tectonic evolution affects the deposition process.The lacustrine,transitional and marine sedimentation corresponds to different tectonic conditions.The lacustrine sedimentation is formed under fault activity during the rifting stage.The transitional sedimentation is formed under weak fault activity during the late rifting stage.The marine sedimentation is formed under weak fault activity and depression activity during the rifting-depression and depression stages.4、The half graben is beneficial for the formation of lacustrine source rocks,which is responsible for the hydrocarbon-rich sag.Therefore the half graben mode contributes to the hydrocarbon-rich sags.
文摘Voltage sages are classified in seven types that in each type, the voltage amplitude and angle of phase voltages are different. We demonstrated that voltage sag types have different effects on synchronous motor, especially on its torque pulsations. Torque pulsations are different in shape of oscillations and moreover, peak torque when voltage magnitude is restored has different correlation with sag duration, as sag type varies. By flux trajectory analysis, we mathematically extracted the critical durations for different types of voltage sags, in the case that the sag begins at the zero angle of the voltage wave. In order to observe the validity of the results, we simulated a synchronous motor subjected to different types of voltage sags. The simulation results confirmed the claim.
基金supported by National Natural Science Foundation of China (No.51321005)Independent Research Program of Tsinghua University (No.20151080416)Area Foundation of National Natural Science Foundation of China (No.51567021)
文摘Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage sags.To overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is proposed.Based on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive power.And the injected currents are kept within safety values for a better utilization of the VSG power capacity.Furthermore,the experimental platform is built.Experimental results demonstrate the validness and effectiveness of the proposed control strategy.
基金The work was supported by the National Science and Technology Major Project of China(No.2011ZX05006-003)the Natural Science Foundation of China(No.41372132).
文摘Pressure fields of different sags in a petroliferous basin were significantly different,and it was related to hydrocarbon enrichment.Based on pressure data of different sags in Bohai Bay Basin,types of pressure field and its distribution characteristics were well discussed,and relationships between overpressure and hydrocarbon generation,pressure field and hydrocarbon enrichment were also investigated.Results showed that the Paleogene pressure fields of different sags in Bohai Bay Basin could be divided into three types:normal pressure type,single overpressure type and double overpressure type.These three types of pressure fields had the zoned features in their distributions.The normal pressure fields were mostly distributed in peripheral sags of the basin,while the single overpressure fields were widespread in the basin,and the double overpressure fields were concentrated in the areas around the Bohai Sea.Hydrocarbon generation had a significant effect on overpressure formation,thus overpressure horizons generally were corresponded to major source rock horizons,and differences of filling evolution history and main hydrocarbon-generation strata of different sags might be important factors for the formation of these three types of pressure fields.Overpressure in source rock horizons was closely related to hydrocarbon enrichment.Horizontally,hydrocarbons were mainly distributed around the overpressure center,and the secondary migration distance of hydrocarbons was affected by the degree of overpressure.Vertically,hydrocarbon distributionwas controlled by the type of pressure fields.Hydrocarbons in the normal pressure sags were mainly enriched in the major hydrocarbon-generation horizons and their adjacent horizons,hydrocarbons in the single overpressure sags were mainly distributed in the hydrocarbon-generation horizons and its upper and lower horizons,while in the double overpressure sags,the hydrocarbon enrichment degree in Neogene was high.Hydrocarbon enrichment in sags was controlled by the degree of overpressure in hydrocarbon-generation horizons,and these oil-rich sags had relatively large overpressure degree.
基金supported by the Fondo de Sustentabilidad Energética SENER-Conacyt,México(No.246949,No.249795)。
文摘In practice,an equilibrium point of the power system is considered transiently secure if it can withstand a specified contingency by maintaining transient evolution of rotor angles and voltage magnitudes within set bounds.A novel sequential approach is proposed to obtain transiently stable equilibrium points through the preventive control of transient stability and transient voltage sag(TVS)problems caused by a severe disturbance.The proposed approach conducts a sequence of non-heuristic optimal active power re-dispatch of the generators to steer the system toward a transiently secure operating point by sequentially solving the transient-stability-constrained optimal power flow(TSC-OPF)problems.In the proposed approach,there are two sequential projection stages,with the first stage ensuring the rotor angle stability and the second stage removing TVS in voltage magnitudes.In both projection stages,the projection operation corresponds to the TSC-OPF,with its formulation directly derived by adding only two steady-state variable-based transient constraints to the conventional OPF problem.The effectiveness of this approach is numerically demonstrated in terms of its accuracy and computational performance by using the Western System Coordinated Council(WSCC)3-machine 9-bus system and an equivalent model of the Mexican 46-machine 190-bus system.
基金supported by the Project funded by the Natural Science Foundation of Hainan Province(Grant No.322QN248)the National Natural Science Foundation of China(Grant Nos.32401488,32060409,32371782 and 32460358)+3 种基金the Innovational Fund for Scientific and Technological Personnel of Hainan Province(Grant No.KJRC 2023C21)the Hainan High-level Talents Project(Grant No.321RC475)Collaborative Innovation Center Project of Nanfan and High-Efficiency Tropical Agriculture in Hainan University(XTCX2022NYB08)Collaborative Innovation Center Project of Ecological Civilization in Hainan University(XTCX2022STC10).
文摘Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity.Previous research has demonstrated that hydrogen peroxide(H_(2)O_(2)),specifically H_(2)O_(2)derived from roots and mediated by the respiratory burst oxidase homolog(NADPH),plays a significant role in regulating ion and plant hormone homeostasis in glycophytic plants,such as Arabidopsis.However,the extent to which root-derived H_(2)O_(2)fulfils similar functions in halophytic plants remains uncertain.Therefore,our study aimed to explore the potential contribution of root-sourced H_(2)O_(2)in delaying leaf senescence induced by high salinity,utilizing seashore paspalum as a model halophytic plant.The application of the NADPH-oxidase inhibitor DPI,coupled with a series of leaf senescence analyses,we revealed that root-derived H_(2)O_(2)significantly retards salt-induced leaf senescence.Furthermore,through the application of hormone analysis,lipidomics,ionomics,Non-invasive Micro-test Technology(NMT),and transcriptomics,we established that NADPH-dependent H_(2)O_(2)induced by salt stress in the roots was indispensable for maintaining the balance of the aging hormone,jasmonic acid(JA),and sodium ion homeostasis within this halophytic plant.Finally,by utilizing AtrbohD Arabidopsis mutants and virus-induced gene silencing(VIGs)in Paspalum vaginatum,we demonstrated the pivotal role played by root-sourced H_(2)O_(2)in upholding JA homeostasis and regulating JA-triggered leaf senescence in P.vaginatum.This study offers novel insights into the mechanisms that govern plant leaf senescence and its response to salinity-induced stress.
基金financially supported by the State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development(33550000-22-ZC0613-0006)National Natural Science Foundation of China(42202133)+2 种基金CNPC Innovation Fund(2022DQ02-0106)Strategic Cooperation Technology Projects of the CNPC and CUPB(ZLZX2020-01-05)Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences),Ministry of Education,China(TPR-2023-05)。
文摘Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.
