The Class-Ⅲ oil reservoirs of Lasaxing oilfield in the Daqing Oil Fields complex have geological oil reserves of 1.86 billion tonnes,an oil recovery of 39%,with remaining reserves accounting for more than 45%of the t...The Class-Ⅲ oil reservoirs of Lasaxing oilfield in the Daqing Oil Fields complex have geological oil reserves of 1.86 billion tonnes,an oil recovery of 39%,with remaining reserves accounting for more than 45%of the total geological reserves of the oilfield.Therefore,they have considerable potential for future oil production.The current layered injection technologies fail to achieve effective control over the low single-layer injection rates since they can only produce low throttle differential pressure under low injection rates(5-20 m^(3)/d).In this study,a symmetrically-structured double-offset-hole injection allocator and a novel throttling component were developed.Their spatial layout was constructed and mechanical parameters were optimized using finite element analysis,which allows for expanding the flow rate range at low injection rates.According to experimental results,the throttle differential pressure increased from 0.2 MPa to 0.8 MPa at an injection rate of 5 m^(3)/d,and the range of the single-layer flow rates expanded from 20-70 m^(3)/d to 5-70 m3/d.The field test results show that the effective production of oil layers with medium and low permeability was achieved and that the ratio of producing oil layer thickness to the total reservoir thickness increased by 9.7%on average.Therefore,this study provides valuable technical support for the effective chemical-flooding-based development of Class-Ⅲ oil reservoirs.展开更多
As a smart spectrum sharing technology, Cognitive Radio (CR) is becoming a hot topic in the field of wireless telecommunications. Besides providing traditional services, the cognitive radio network Media Access Contro...As a smart spectrum sharing technology, Cognitive Radio (CR) is becoming a hot topic in the field of wireless telecommunications. Besides providing traditional services, the cognitive radio network Media Access Control (MAC) layer is required to perform an entirely new set of functions for effective reusing spectrum opportunity, without causing any harmful interference to incumbents. Spectrum sensing management selects and optimizes sensing strategies and parameters by the selection of sensing mode, sensing period, sensing time, sensing channel, and sensing quiet period. Access control avoids collision with primary users mainly by cooperation access and transparent access. Dynamic spectrum allocation optimizes the allocation of uncertain spectrum for binary interference model and accumulative interference model. Security mechanism adds authentication and encryption mechanisms to MAC frame to defense MAC layer security attacks. Cross-layer design combines MAC layer information with physical layer or higher layers information, such as network layer, transmission layer, to achieve global optimization.展开更多
Despite the rapid development in Worldwide Interoperability for Microwave Access (WiMAX) technologies,key technologies for the Physical Layer (PHY) still need to be further improved so as to achieve highly efficient a...Despite the rapid development in Worldwide Interoperability for Microwave Access (WiMAX) technologies,key technologies for the Physical Layer (PHY) still need to be further improved so as to achieve highly efficient and reliable communication performance,as well as to support a mobile environment with a higher transmisison rate. As an amendment to IEEE 802.16d (for fixed broadband wireless access systems),IEEE 802.16e (for mobile broadband wireless access systems) introduces the Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) technologies into the PHY,doubling the transmission rate while supporting a certain degree of mobility. In the future,more advanced Air Interface (AI) technology is to be applied in the IEEE 802.16m standard.展开更多
基金sponsored by the key consulting project of the Chinese Academy of Engineering entitled Research on the Sustainable Development Strategy of China's High Water-cut Old Oilfields(No.2019-XZ-15)the National major project entitled Large Oil and Gas Field and Coalbed Methane Development(No.:2016ZX05010006).
文摘The Class-Ⅲ oil reservoirs of Lasaxing oilfield in the Daqing Oil Fields complex have geological oil reserves of 1.86 billion tonnes,an oil recovery of 39%,with remaining reserves accounting for more than 45%of the total geological reserves of the oilfield.Therefore,they have considerable potential for future oil production.The current layered injection technologies fail to achieve effective control over the low single-layer injection rates since they can only produce low throttle differential pressure under low injection rates(5-20 m^(3)/d).In this study,a symmetrically-structured double-offset-hole injection allocator and a novel throttling component were developed.Their spatial layout was constructed and mechanical parameters were optimized using finite element analysis,which allows for expanding the flow rate range at low injection rates.According to experimental results,the throttle differential pressure increased from 0.2 MPa to 0.8 MPa at an injection rate of 5 m^(3)/d,and the range of the single-layer flow rates expanded from 20-70 m^(3)/d to 5-70 m3/d.The field test results show that the effective production of oil layers with medium and low permeability was achieved and that the ratio of producing oil layer thickness to the total reservoir thickness increased by 9.7%on average.Therefore,this study provides valuable technical support for the effective chemical-flooding-based development of Class-Ⅲ oil reservoirs.
基金supported by the National Natural Science Foundation of China under Grant No.60772110.
文摘As a smart spectrum sharing technology, Cognitive Radio (CR) is becoming a hot topic in the field of wireless telecommunications. Besides providing traditional services, the cognitive radio network Media Access Control (MAC) layer is required to perform an entirely new set of functions for effective reusing spectrum opportunity, without causing any harmful interference to incumbents. Spectrum sensing management selects and optimizes sensing strategies and parameters by the selection of sensing mode, sensing period, sensing time, sensing channel, and sensing quiet period. Access control avoids collision with primary users mainly by cooperation access and transparent access. Dynamic spectrum allocation optimizes the allocation of uncertain spectrum for binary interference model and accumulative interference model. Security mechanism adds authentication and encryption mechanisms to MAC frame to defense MAC layer security attacks. Cross-layer design combines MAC layer information with physical layer or higher layers information, such as network layer, transmission layer, to achieve global optimization.
文摘Despite the rapid development in Worldwide Interoperability for Microwave Access (WiMAX) technologies,key technologies for the Physical Layer (PHY) still need to be further improved so as to achieve highly efficient and reliable communication performance,as well as to support a mobile environment with a higher transmisison rate. As an amendment to IEEE 802.16d (for fixed broadband wireless access systems),IEEE 802.16e (for mobile broadband wireless access systems) introduces the Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) technologies into the PHY,doubling the transmission rate while supporting a certain degree of mobility. In the future,more advanced Air Interface (AI) technology is to be applied in the IEEE 802.16m standard.
