Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the ...Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the northern region in terms of aeolian sand geomorphology and formation environment. Based on the field ob- servation data of airflow and aeolian sand transport, continuous monitoring data of erosional and depositional processes between 14 April 2009 and 9 April 2011 and data of surface sand grains from the classical section along the southern edge of the Taklimakan Desert Highway, this paper reported the blown sand motion within the sand-control system of the highway. The main results are as follows： 1） The existing sand-control system is highly effective in preventing and controlling desertification. Wind velocities within the sand-control system were ap- proximately 33%-100% of those for the same height above the mobile sand surface. Aeolian sand fluxes were approximately 0-31.21% of those of the mobile sand surface. Sand grains inside the system, with a mean diameter of 2.89 q）, were finer than those （2.15 q）） outside the system. In addition, wind velocities basically followed a loga- rithmic law, but the airflow along the classical section was mainly determined by topography and vegetation. 2） There were obvious erosional and depositional phenomena above the surface within the sand-control system, and these phenomena have very consistent patterns for all observation points in the two observed years. The total thicknesses of erosion and deposition ranged from 0.30 to 14.60 cm, with a mean value of 3.67 cm. In contrast, the deposition thicknesses were 1.90-22.10 cm, with a mean value of 7.59 cm, and the erosion thicknesses were 3.51-15.10 cm, with a mean value of 8.75 cm. The results will aid our understanding of blown sand within the sand-control system and provide a strong foundation for optimizing the sand-control system.展开更多
As the longest desert highway in China. the 447-kin-long Taklimakan Desert Highway which goes across the Taklimakan Desert was fully opened to traffic in 1996~[1]. The sand-controlling system along the Desert Highway ...As the longest desert highway in China. the 447-kin-long Taklimakan Desert Highway which goes across the Taklimakan Desert was fully opened to traffic in 1996~[1]. The sand-controlling system along the Desert Highway enables the Highway itself to operate properly and creates enormous socio-economic benefits. However, due to delivery time pressure, the sand-controlling system was built in a haste. Lack of studies on sand-controlling system brought deficiencies on design and construction of the sand-controlling system. And with the lapse of time, troubles such as sand deposition on the roadbeds and erosion on roadsides came to surface and caused more serious problems for the traffic routes[1.2]. This paper discusses two forms of the sand-controlling system-the upright fence and the send-covered sand barrier, then analyzes the general benefits of the sandcontrolling system along the Desert Highway.展开更多
Concrete-plate fences have been widely adopted for windblown sand control and mitigation along railways.However,the inclination angles of inserting the concrete plate with respect to the vertical direction,i.e.,straig...Concrete-plate fences have been widely adopted for windblown sand control and mitigation along railways.However,the inclination angles of inserting the concrete plate with respect to the vertical direction,i.e.,straight or obliquely inserted concrete plates(SIP or OIP),significantly influence the efficiency of sand-control.This study performs a comparative evaluation of the SIP and OIP sand-control fences using wind tunnel testing and field monitoring data collected from the Lanzhou–Wulumuqi High-Speed Railway Project.The results show that the fence’s ability to reduce the wind speed and the sand-retaining efficiency gradually weakens with the increasing wind speed.Compared with the SIP fence,the OIP fence has a better wind speed reduction capability,stronger ability to capture fine particles below the top of the fence;it is more efficient for sand-retaining and induces stronger eddy intensity.Generally,the wind tunnel test and field monitoring results are consistent,whereas wind tunnel tests incline to overestimate wind speed reduction and sand-control efficiency.The study also finds that the aeolian sand accumulated around the fence can weaken the protection efficiency,and hence cleaning the aeolian sand accumulated around the fence should be done periodically to ensure the designed functions.展开更多
Gravel packing is a promising sand control method for natural gas wells in deepwater environments.However,premature screenout,wellbore shrinkage,and packer installationlimit gravel packing efficiency in long-reach hor...Gravel packing is a promising sand control method for natural gas wells in deepwater environments.However,premature screenout,wellbore shrinkage,and packer installationlimit gravel packing efficiency in long-reach horizontal wells.In this paper,we introduce a novel multi-path screen that provides alternative pathways once the circulating annulus is blocked.The basic geometric parameters of the screen are given first.Then,the frictional pressure loss in each circulating unit during packing is evaluated.Finally,the application of this screen in a long-reach horizontal well in the northern South China Sea is discussed.The application results demonstrate the applicability of multi-path screens in complex downhole completion conditions.The multi-path screen described here may widen the application ranges of gravel packing techniques to meet the exploitation demand for unconventional natural gas resources,such as marine natural gas hydrate.展开更多
为了满足固沙机功能集成化、智能化方向发展需求,设计了一种智能草沙障固沙机控制系统,采用主从式控制系统结构,以双Arduino Mega 2560为核心主控器,使用模块化对控制系统的硬件和软件进行设计;纵向铺设控制模块、底盘升降控制模块和播...为了满足固沙机功能集成化、智能化方向发展需求,设计了一种智能草沙障固沙机控制系统,采用主从式控制系统结构,以双Arduino Mega 2560为核心主控器,使用模块化对控制系统的硬件和软件进行设计;纵向铺设控制模块、底盘升降控制模块和播种控制模块采用增量式PID控制算法;横向铺设控制模块采用位置式PID控制算法,并结合YOLOv3实现草沙障的检测追踪;以触摸屏和基于蓝牙的固沙机控制Android APP为人机交互界面。控制系统试验结果表明:基于PID算法检测追踪方式与直插式铺设方式相比,采用检测追踪方式固沙机的横向犁沙宽度减小了78.7%,整车振动减小了42.6%,草沙障铺设和播种测试功能均达到样机设计预期,为智能化固沙机研究提供了一种切实可行的设计方案。展开更多
基金supported by the National Natural Science Foundation of China (41271020, 41330746)CERS-China Equipment and Education Resources System (CERS-1-109)
文摘Although scientists have performed many studies in the Taklimakan Desert, few of them have reported the blown sand motion along the southern edge of the Taklimakan Desert Highway, which differs significantly from the northern region in terms of aeolian sand geomorphology and formation environment. Based on the field ob- servation data of airflow and aeolian sand transport, continuous monitoring data of erosional and depositional processes between 14 April 2009 and 9 April 2011 and data of surface sand grains from the classical section along the southern edge of the Taklimakan Desert Highway, this paper reported the blown sand motion within the sand-control system of the highway. The main results are as follows： 1） The existing sand-control system is highly effective in preventing and controlling desertification. Wind velocities within the sand-control system were ap- proximately 33%-100% of those for the same height above the mobile sand surface. Aeolian sand fluxes were approximately 0-31.21% of those of the mobile sand surface. Sand grains inside the system, with a mean diameter of 2.89 q）, were finer than those （2.15 q）） outside the system. In addition, wind velocities basically followed a loga- rithmic law, but the airflow along the classical section was mainly determined by topography and vegetation. 2） There were obvious erosional and depositional phenomena above the surface within the sand-control system, and these phenomena have very consistent patterns for all observation points in the two observed years. The total thicknesses of erosion and deposition ranged from 0.30 to 14.60 cm, with a mean value of 3.67 cm. In contrast, the deposition thicknesses were 1.90-22.10 cm, with a mean value of 7.59 cm, and the erosion thicknesses were 3.51-15.10 cm, with a mean value of 8.75 cm. The results will aid our understanding of blown sand within the sand-control system and provide a strong foundation for optimizing the sand-control system.
基金program introducting distinguished personnel from abroad/wind-blown sand physics project Chinese Academy of Sciences
文摘As the longest desert highway in China. the 447-kin-long Taklimakan Desert Highway which goes across the Taklimakan Desert was fully opened to traffic in 1996~[1]. The sand-controlling system along the Desert Highway enables the Highway itself to operate properly and creates enormous socio-economic benefits. However, due to delivery time pressure, the sand-controlling system was built in a haste. Lack of studies on sand-controlling system brought deficiencies on design and construction of the sand-controlling system. And with the lapse of time, troubles such as sand deposition on the roadbeds and erosion on roadsides came to surface and caused more serious problems for the traffic routes[1.2]. This paper discusses two forms of the sand-controlling system-the upright fence and the send-covered sand barrier, then analyzes the general benefits of the sandcontrolling system along the Desert Highway.
基金supported by the Science and Technology Development Plan of China Railway Group Limited(Grant No.2015-kj035-g004-03).
文摘Concrete-plate fences have been widely adopted for windblown sand control and mitigation along railways.However,the inclination angles of inserting the concrete plate with respect to the vertical direction,i.e.,straight or obliquely inserted concrete plates(SIP or OIP),significantly influence the efficiency of sand-control.This study performs a comparative evaluation of the SIP and OIP sand-control fences using wind tunnel testing and field monitoring data collected from the Lanzhou–Wulumuqi High-Speed Railway Project.The results show that the fence’s ability to reduce the wind speed and the sand-retaining efficiency gradually weakens with the increasing wind speed.Compared with the SIP fence,the OIP fence has a better wind speed reduction capability,stronger ability to capture fine particles below the top of the fence;it is more efficient for sand-retaining and induces stronger eddy intensity.Generally,the wind tunnel test and field monitoring results are consistent,whereas wind tunnel tests incline to overestimate wind speed reduction and sand-control efficiency.The study also finds that the aeolian sand accumulated around the fence can weaken the protection efficiency,and hence cleaning the aeolian sand accumulated around the fence should be done periodically to ensure the designed functions.
基金supported by the National Natural Science Foundation of China(Grant No.41976074)Key Laboratory of Gas Hydrate,Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences(Grant No.E129kf1301).
文摘Gravel packing is a promising sand control method for natural gas wells in deepwater environments.However,premature screenout,wellbore shrinkage,and packer installationlimit gravel packing efficiency in long-reach horizontal wells.In this paper,we introduce a novel multi-path screen that provides alternative pathways once the circulating annulus is blocked.The basic geometric parameters of the screen are given first.Then,the frictional pressure loss in each circulating unit during packing is evaluated.Finally,the application of this screen in a long-reach horizontal well in the northern South China Sea is discussed.The application results demonstrate the applicability of multi-path screens in complex downhole completion conditions.The multi-path screen described here may widen the application ranges of gravel packing techniques to meet the exploitation demand for unconventional natural gas resources,such as marine natural gas hydrate.
文摘为了满足固沙机功能集成化、智能化方向发展需求,设计了一种智能草沙障固沙机控制系统,采用主从式控制系统结构,以双Arduino Mega 2560为核心主控器,使用模块化对控制系统的硬件和软件进行设计;纵向铺设控制模块、底盘升降控制模块和播种控制模块采用增量式PID控制算法;横向铺设控制模块采用位置式PID控制算法,并结合YOLOv3实现草沙障的检测追踪;以触摸屏和基于蓝牙的固沙机控制Android APP为人机交互界面。控制系统试验结果表明:基于PID算法检测追踪方式与直插式铺设方式相比,采用检测追踪方式固沙机的横向犁沙宽度减小了78.7%,整车振动减小了42.6%,草沙障铺设和播种测试功能均达到样机设计预期,为智能化固沙机研究提供了一种切实可行的设计方案。
