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
In the field of 3 D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir typ...In the field of 3 D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir type, the comparability and practicality of quantitative assessment will be emerging. The evaluation system should include three parts: data verification, geological understanding and process check. Data verification mainly involves testing the accuracy of local prediction with actual data, and geological understanding is to examine whether the global estimation honors geological principles and prior insights. Process check is also indispensable to avoid occasionality. To this end, we produced a set of assessment criteria, taking complex fault-block sandstone oil reservoir as an example. To be specific, thirteen characteristic parameters were totally selected, setting weights according to their rated importance, formulating three-level evaluation standards in a centesimal system for each characteristic parameter, and obtaining the final assessment based on the cumulative score. The results indicate that such evaluation can not only access the quality of the model objectively and comprehensively, but also identify the aspects in need of improvement through the deduction items.展开更多
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
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Supported by the Sinopec Science and Technology Major Project(G5800-17-ZS-KJB009)
文摘In the field of 3 D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir type, the comparability and practicality of quantitative assessment will be emerging. The evaluation system should include three parts: data verification, geological understanding and process check. Data verification mainly involves testing the accuracy of local prediction with actual data, and geological understanding is to examine whether the global estimation honors geological principles and prior insights. Process check is also indispensable to avoid occasionality. To this end, we produced a set of assessment criteria, taking complex fault-block sandstone oil reservoir as an example. To be specific, thirteen characteristic parameters were totally selected, setting weights according to their rated importance, formulating three-level evaluation standards in a centesimal system for each characteristic parameter, and obtaining the final assessment based on the cumulative score. The results indicate that such evaluation can not only access the quality of the model objectively and comprehensively, but also identify the aspects in need of improvement through the deduction items.
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.
