The high-voltage direct current(HVDC)grid has been recognized as an effective solution for renewable energy integration.Currently,two main development trends for HVDC grids are being studied:a DC breaker based HVDC gr...The high-voltage direct current(HVDC)grid has been recognized as an effective solution for renewable energy integration.Currently,two main development trends for HVDC grids are being studied:a DC breaker based HVDC grid and fault-blocking converter based HVDC grid.Although the former has a perfect performance for fault clearance,its development is still highly constrained by the cost and maturity of DC breakers.The latter can extinguish DC faults by the fault-blocking converters.Without using DC breakers,there is no bottleneck in its technical feasibility.Nevertheless,in fault scenarios,such types of HVDC grids will be blocked at length for air-deionization,which is its main drawback.The aim of this paper is to minimize its power interruption time,by optimizing protection coordination strategies.To cover the most complex cases,the overhead line applications,in which the reclosure actions are required to be implemented,are considered.In this paper,the protection requirements of HVDC grids are first discussed,then the benefits of fault-blocking modular multilevel converters(MMCs)and their fault features are analyzed.Based on this,a control function is designed to reduce the air-deionization time.To minimize the influence of the DC faults,a separation methodology for restarting the system is proposed.The effectiveness of the proposed protection coordination schemes is validated by PSCAD/EMTDC simulations.展开更多
The long-term stability of CO_(2) storage represents a pivotal challenge in geological CO_(2) storage(CGS),particularly within deep saline aquifers characterized by complex fault-block systems.While the injection site...The long-term stability of CO_(2) storage represents a pivotal challenge in geological CO_(2) storage(CGS),particularly within deep saline aquifers characterized by complex fault-block systems.While the injection sites and rate under different fault structures will directly affect the CO_(2) storage effect and the risk of leakage.This study investigates the Gaoyou Sag in the Subei Basin,a representative fault-block reservoir,through an integrated numerical-experimental approach.A three-dimensional simulation model incorporating multiphase flow dynamics was developed to characterize subsurface CO_(2) transport and dissolution processes.A novel fault seal capacity evaluation framework was proposed,integrating three critical geological indices(fault throw/reservoir thickness/caprock thicknesses)with the coupling of formation physical properties,temperature,and pressure for the rational selection of injection sites and rates.The results show that Optimal storage performance is observed when the fault throw is lower than the reservoir and caprock thicknesses.Furthermore,higher temperature and pressure promote the dissolution and diffusion of CO_(2),while compared to the structural form of faults,the physical properties of faults have a more significant effect on CO_(2) leakage.The larger reservoir space and the presence of an interlayer reduce the risk of CO_(2) leakage,and augmenting storage potential.Decreasing the injection rate increases the proportion of dissolved CO_(2),thereby enhancing the safety of CO_(2) storage.展开更多
Current methods for the analysis of channeling-path phenomena in reservoirs cannot account for the influence of time and space on the actual seepage behavior.In the present study,this problem is addressed considering ...Current methods for the analysis of channeling-path phenomena in reservoirs cannot account for the influence of time and space on the actual seepage behavior.In the present study,this problem is addressed considering actual production data and dynamic characteristic parameters quantitatively determined in the near wellbore area by fitting the water-cut curve of the well.Starting from the dynamic relationship between injection and production data,the average permeability is determined and used to obtain a real-time quantitative characterization of the seepage behavior of the channeling-path in the far wellbore area.For the considered case study(Jidong oilfield),it is found that the seepage capacity of the channeling-path in the far wellbore area is far less(10 times smaller)than that of the channeling-path in the near wellbore area.The present study and the proposed model(combining near wellbore area and far wellbore area real-time data)have been implemented to support the definition of relevant adjustment measures to ultimately improve oil recovery.展开更多
In the process of oilfield development, oilfield dewatering project has always been a big problem for oilfield developers. Because the original oilfield development technology uses a single well, the efficiency of the...In the process of oilfield development, oilfield dewatering project has always been a big problem for oilfield developers. Because the original oilfield development technology uses a single well, the efficiency of the single well is very low, which results in the deterioration of the effect in the development process of many oilfields and the loss in oilfield development. Therefore, in order to improve the benefit of oilfield development and the effect of water flooding development, this paper makes an in-depth study on the water-stable and oil-efficient development of high-water-cut and later-stage complex fault-block oilfields.展开更多
This paper describes the identification of waterflooded zones and the impact of waterflooding on reservoir properties of sandstones of the Funing Formation at the Gao 6 Fault-block of the Gaoji Oilfield,in the Subei B...This paper describes the identification of waterflooded zones and the impact of waterflooding on reservoir properties of sandstones of the Funing Formation at the Gao 6 Fault-block of the Gaoji Oilfield,in the Subei Basin,east China.This work presents a new approach based on a back-propagation neural network using well log data to train the network,and then generating a cross-plot plate to identify waterflooded zones.A neural network was designed and trained,and the results show that the new method is better than traditional methods.For a comparative study,two representative wells at the Gao 6 Fault-block were chosen for analysis:one from a waterflooded zone,and the other from a zone without waterflooding.Results from this analysis were used to develop a better understanding of the impact of waterflooding on reservoir properties.A range of changes are shown to have taken place in the waterflooded zone,including changes in microscopic pore structure,fluids,and minerals.展开更多
Fault-block structures of the Altay-Sayan folded area （ASFA） southeastern Siberia of Russia were used as the basis for creating a 3-D model. The surface structures were projected to depths by previous correlations b...Fault-block structures of the Altay-Sayan folded area （ASFA） southeastern Siberia of Russia were used as the basis for creating a 3-D model. The surface structures were projected to depths by previous correlations between long and deep faults, with all layers and deformation factors defined. The mean deformation factor （Ds） is 0.12 unit/km^3 in the upper layer, 0.012 unit/km^3 in the intermediate layer, and 0.007 unit/km^3 in the lower layer of the 3-D ASFA neotectonic model. Ds allows correlation of the three distinguished layers with theological bodies that differ in their potential for accumulating elastic energy. 3-D modeling can be used as a methodological approach to projections in seismic prone areas such as the Krasnoyarsk region, for earthquake-hazard monitoring.展开更多
Low-temperature thermochronology is a widely used tool for revealing denudation histories of mountain ranges. Although this technique has been applied mainly to continental orogens, such as the European Alps, Himalaya...Low-temperature thermochronology is a widely used tool for revealing denudation histories of mountain ranges. Although this technique has been applied mainly to continental orogens, such as the European Alps, Himalayas, and Andes, recent technological development of low-temperature thermochronology has made it applicable to a wider variety of mountain ranges with various sizes and tectonic histories. The Japanese Islands comprise young and active island arcs, where an early stage of mountain range formation is observed. Numerous attempts have been made to constrain the uplift and denudation histories of the mountains in the Japanese Islands using geologic, geomorphologic, or geodetic methods. However, the number of thermochronometric attempts has been limited primarily due to the small amount of total denudation since the initiation of the uplift. In this review paper, we introduce the tectonic and geomorphic settings of the mountain ranges in the Japanese Islands, and discuss previous attempts to estimate uplift or denudation of the Japanese mountains using methods other than ther- mochronology. Furthermore, we discuss problems of the thermochronometric applications in revealing denudation histories of the Japanese mountains. Finally, we present a case study of the Kiso Range in central Japan and discuss the current effectiveness and applicability of low-temperature thermochronology to the Japanese mountainous areas.展开更多
The highest priorities of any civilized country are in providing interests of social safety.The anthropogenic influence on geological environment is becoming greater because of the human activities increase. That’s w...The highest priorities of any civilized country are in providing interests of social safety.The anthropogenic influence on geological environment is becoming greater because of the human activities increase. That’s why anthropogenic-tectonic earthquake problem has become important recently.It appeared as a hypothesis in the 30 s and became much clearer in 60 s.The anthropogenic-tectonic earthquake epiceneters are located not far from the surface and,as a rule。展开更多
Due to its superior performance on the efficient exploitation of a small fault-block reservoir,a novel technique of fracturing-huff-n-percolation-puff(FHnPP)has received increasing attentions in recent years.In order ...Due to its superior performance on the efficient exploitation of a small fault-block reservoir,a novel technique of fracturing-huff-n-percolation-puff(FHnPP)has received increasing attentions in recent years.In order to clearly identify and understand the associated mechanisms,reservoir simulations have been conducted to evaluate performance of an FHnPP process in a hydrocarbon reservoir.A series of simulation scenarios are designed to evaluate and identify dominant factors based on both single-factor and orthogonal schemes.The FHnPP performance can be understood as follows,i.e.,created(micro-)fractures are extended from the surrounding water-zone deeper into formation during water injection,this process rebuilds the pressure field,enabling more trapped oil to be subsequently driven backwards the well after such(micro-)fractures are closed or partially-closed.Surfactants effectively reduce the water/oil interfacial tension(IFT),but it only increases oil production at early times.The existence of secondary fractures slightly enhances oil recovery at early puff-period after which such a positive impact is gradually vanished.A higher matrix permeability yields a higher ultimate oil recovery,but such a yielded positive effect from fracturing is then degraded.Moreover,the residual permeability of fractures during production(i.e.,the puff process)negatively affect oil recovery,while a longer length of fracture results in more produced oil.Also,both injection rate and soaking time positively affect the oil recovery though the latter is insignificant.The orthogonal analysis indicates that,sensitivity of the dominant factors affecting oil recovery varies from each other,while the sensitivity of FHnPP's advantages to those factors is found also unequal.In the target reservoir with the optimized FHnPP parameters,significant oil increment(i.e.,a recovery factor(RF)of 3.59%(i.e.,609.1 m^(3) oil))can be achieved compared with that of the traditional huff-n-puff(THnP)process.This numerical study not only proves the feasibility and advantages of the FHnPP technique,but also deepens our understanding of its performance and identifies the dominating factors.展开更多
文摘The high-voltage direct current(HVDC)grid has been recognized as an effective solution for renewable energy integration.Currently,two main development trends for HVDC grids are being studied:a DC breaker based HVDC grid and fault-blocking converter based HVDC grid.Although the former has a perfect performance for fault clearance,its development is still highly constrained by the cost and maturity of DC breakers.The latter can extinguish DC faults by the fault-blocking converters.Without using DC breakers,there is no bottleneck in its technical feasibility.Nevertheless,in fault scenarios,such types of HVDC grids will be blocked at length for air-deionization,which is its main drawback.The aim of this paper is to minimize its power interruption time,by optimizing protection coordination strategies.To cover the most complex cases,the overhead line applications,in which the reclosure actions are required to be implemented,are considered.In this paper,the protection requirements of HVDC grids are first discussed,then the benefits of fault-blocking modular multilevel converters(MMCs)and their fault features are analyzed.Based on this,a control function is designed to reduce the air-deionization time.To minimize the influence of the DC faults,a separation methodology for restarting the system is proposed.The effectiveness of the proposed protection coordination schemes is validated by PSCAD/EMTDC simulations.
基金the Beijing Natural Science Foundation(No.8232044)the Science Foundation of China University of Petroleum,Beijing(No.2462023BJRC030).
文摘The long-term stability of CO_(2) storage represents a pivotal challenge in geological CO_(2) storage(CGS),particularly within deep saline aquifers characterized by complex fault-block systems.While the injection sites and rate under different fault structures will directly affect the CO_(2) storage effect and the risk of leakage.This study investigates the Gaoyou Sag in the Subei Basin,a representative fault-block reservoir,through an integrated numerical-experimental approach.A three-dimensional simulation model incorporating multiphase flow dynamics was developed to characterize subsurface CO_(2) transport and dissolution processes.A novel fault seal capacity evaluation framework was proposed,integrating three critical geological indices(fault throw/reservoir thickness/caprock thicknesses)with the coupling of formation physical properties,temperature,and pressure for the rational selection of injection sites and rates.The results show that Optimal storage performance is observed when the fault throw is lower than the reservoir and caprock thicknesses.Furthermore,higher temperature and pressure promote the dissolution and diffusion of CO_(2),while compared to the structural form of faults,the physical properties of faults have a more significant effect on CO_(2) leakage.The larger reservoir space and the presence of an interlayer reduce the risk of CO_(2) leakage,and augmenting storage potential.Decreasing the injection rate increases the proportion of dissolved CO_(2),thereby enhancing the safety of CO_(2) storage.
基金supported by Bohai Oilfield Efficient Development Demonstration Project(2016ZX05058-003-011).
文摘Current methods for the analysis of channeling-path phenomena in reservoirs cannot account for the influence of time and space on the actual seepage behavior.In the present study,this problem is addressed considering actual production data and dynamic characteristic parameters quantitatively determined in the near wellbore area by fitting the water-cut curve of the well.Starting from the dynamic relationship between injection and production data,the average permeability is determined and used to obtain a real-time quantitative characterization of the seepage behavior of the channeling-path in the far wellbore area.For the considered case study(Jidong oilfield),it is found that the seepage capacity of the channeling-path in the far wellbore area is far less(10 times smaller)than that of the channeling-path in the near wellbore area.The present study and the proposed model(combining near wellbore area and far wellbore area real-time data)have been implemented to support the definition of relevant adjustment measures to ultimately improve oil recovery.
文摘In the process of oilfield development, oilfield dewatering project has always been a big problem for oilfield developers. Because the original oilfield development technology uses a single well, the efficiency of the single well is very low, which results in the deterioration of the effect in the development process of many oilfields and the loss in oilfield development. Therefore, in order to improve the benefit of oilfield development and the effect of water flooding development, this paper makes an in-depth study on the water-stable and oil-efficient development of high-water-cut and later-stage complex fault-block oilfields.
基金Project supported by the National Natural Science Foundation of China (No. 41172109)the National Natural Science Foundation of Shandong Province (No. ZR2011DM009)the Research Foundation for the Doctoral Program of Higher Education (No. 20110003110014),China
文摘This paper describes the identification of waterflooded zones and the impact of waterflooding on reservoir properties of sandstones of the Funing Formation at the Gao 6 Fault-block of the Gaoji Oilfield,in the Subei Basin,east China.This work presents a new approach based on a back-propagation neural network using well log data to train the network,and then generating a cross-plot plate to identify waterflooded zones.A neural network was designed and trained,and the results show that the new method is better than traditional methods.For a comparative study,two representative wells at the Gao 6 Fault-block were chosen for analysis:one from a waterflooded zone,and the other from a zone without waterflooding.Results from this analysis were used to develop a better understanding of the impact of waterflooding on reservoir properties.A range of changes are shown to have taken place in the waterflooded zone,including changes in microscopic pore structure,fluids,and minerals.
文摘Fault-block structures of the Altay-Sayan folded area （ASFA） southeastern Siberia of Russia were used as the basis for creating a 3-D model. The surface structures were projected to depths by previous correlations between long and deep faults, with all layers and deformation factors defined. The mean deformation factor （Ds） is 0.12 unit/km^3 in the upper layer, 0.012 unit/km^3 in the intermediate layer, and 0.007 unit/km^3 in the lower layer of the 3-D ASFA neotectonic model. Ds allows correlation of the three distinguished layers with theological bodies that differ in their potential for accumulating elastic energy. 3-D modeling can be used as a methodological approach to projections in seismic prone areas such as the Krasnoyarsk region, for earthquake-hazard monitoring.
基金supported by a Grantin-Aid for Scientific Research by Japan Society for the Promotion of Science to Hiroyuki Tsutsumi(Grant No.20650155)Grant-inAid for Research by Tokyo Geographical Society to Shigeru Sueoka (research title:uplift and denudation history of the Akaishi Range based on low-temperature thermochronometric methods)
文摘Low-temperature thermochronology is a widely used tool for revealing denudation histories of mountain ranges. Although this technique has been applied mainly to continental orogens, such as the European Alps, Himalayas, and Andes, recent technological development of low-temperature thermochronology has made it applicable to a wider variety of mountain ranges with various sizes and tectonic histories. The Japanese Islands comprise young and active island arcs, where an early stage of mountain range formation is observed. Numerous attempts have been made to constrain the uplift and denudation histories of the mountains in the Japanese Islands using geologic, geomorphologic, or geodetic methods. However, the number of thermochronometric attempts has been limited primarily due to the small amount of total denudation since the initiation of the uplift. In this review paper, we introduce the tectonic and geomorphic settings of the mountain ranges in the Japanese Islands, and discuss previous attempts to estimate uplift or denudation of the Japanese mountains using methods other than ther- mochronology. Furthermore, we discuss problems of the thermochronometric applications in revealing denudation histories of the Japanese mountains. Finally, we present a case study of the Kiso Range in central Japan and discuss the current effectiveness and applicability of low-temperature thermochronology to the Japanese mountainous areas.
文摘The highest priorities of any civilized country are in providing interests of social safety.The anthropogenic influence on geological environment is becoming greater because of the human activities increase. That’s why anthropogenic-tectonic earthquake problem has become important recently.It appeared as a hypothesis in the 30 s and became much clearer in 60 s.The anthropogenic-tectonic earthquake epiceneters are located not far from the surface and,as a rule。
基金a Science Development Grant (No.: DJB2022011) from the Dongying Government of China awarded to Y.Ding, a Discovery Development Grant, a Discovery Grant, and a Collaborative Research and Development (CRD) Grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada and a Mitacs Industry-Faculty Collaboration for Innovation (MIFCI) Grant awarded to D. Yang.
文摘Due to its superior performance on the efficient exploitation of a small fault-block reservoir,a novel technique of fracturing-huff-n-percolation-puff(FHnPP)has received increasing attentions in recent years.In order to clearly identify and understand the associated mechanisms,reservoir simulations have been conducted to evaluate performance of an FHnPP process in a hydrocarbon reservoir.A series of simulation scenarios are designed to evaluate and identify dominant factors based on both single-factor and orthogonal schemes.The FHnPP performance can be understood as follows,i.e.,created(micro-)fractures are extended from the surrounding water-zone deeper into formation during water injection,this process rebuilds the pressure field,enabling more trapped oil to be subsequently driven backwards the well after such(micro-)fractures are closed or partially-closed.Surfactants effectively reduce the water/oil interfacial tension(IFT),but it only increases oil production at early times.The existence of secondary fractures slightly enhances oil recovery at early puff-period after which such a positive impact is gradually vanished.A higher matrix permeability yields a higher ultimate oil recovery,but such a yielded positive effect from fracturing is then degraded.Moreover,the residual permeability of fractures during production(i.e.,the puff process)negatively affect oil recovery,while a longer length of fracture results in more produced oil.Also,both injection rate and soaking time positively affect the oil recovery though the latter is insignificant.The orthogonal analysis indicates that,sensitivity of the dominant factors affecting oil recovery varies from each other,while the sensitivity of FHnPP's advantages to those factors is found also unequal.In the target reservoir with the optimized FHnPP parameters,significant oil increment(i.e.,a recovery factor(RF)of 3.59%(i.e.,609.1 m^(3) oil))can be achieved compared with that of the traditional huff-n-puff(THnP)process.This numerical study not only proves the feasibility and advantages of the FHnPP technique,but also deepens our understanding of its performance and identifies the dominating factors.
