displacement system
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2021 ◽  
Vol 9 ◽  
Author(s):  
Qunpeng Duan ◽  
Yibo Xing ◽  
Kainan Guo

In the present work, we have developed a new indicator displacement system based on pillararene for anionic water-soluble carboxylato pillar [6] arene (WP6) and aromatic fluorescent dye safranine T (ST). A large fluorescence enhancement and colour change of ST were observed after complexation with electron-rich cavity in WP6 because of host-guest twisted intramolecular charge-transfer interactions. The constructed pillararene-indicator displacement system can be applied for caffeine selective detection in water.


2021 ◽  
Vol 11 (22) ◽  
pp. 10818
Author(s):  
Jie Feng ◽  
Buchen Wu ◽  
Shujin Laima

Wind-tunnel experiments are performed to investigate the effects of trailing-edge reattachment on the flutter behaviors of spring-suspended trailing-edge-changeable section models. Different Trailing edges (TE) were fixed at the back of a body to adjust reattachment of the vortex. A laser-displacement system was used to acquire the vibration signals. The relationship between flutter characteristics and TEs that affects the wake mode was analyzed. The results show that the motion of the wake vortex has a certain correlation with the flutter stability of the bridge deck. Limit cycle flutter (LCF) occurs to a section model with a 30° TE, whose amplitude gradually increases as the wind speed increases, and the vibration develops into a hard flutter when the wind speed is 12.43 m/s. A section model with 180 TE reaches a hard flutter when the wind speed is 15.31 m/s, without the stage of LCF. As the TE becomes more and more blunt, the critical wind speed, Us, gradually increases, meaning the flutter stability gradually increases. The results reveal that LCF may still occur to the bridge section with a streamlined front edge, and, in some cases, it also may have a range of wind speeds in which LCF occurs.


Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhenfu Ma ◽  
Kai Zhang ◽  
Mengjie Zhao ◽  
Lu Liu ◽  
Chao Zhong ◽  
...  

In view of the problems of low permeability, high oil viscosity and freezing point, and low productivity of single well in Luo 321 and Luo 36 blocks of Luojia Oilfield, the chemical viscosity-reducing cold production technology was studied. By analyzing the properties of crude oil, it is concluded that the reason for high viscosity and high freezing point is the high content of asphaltene, pectin, and wax. The viscosity is mainly affected by asphaltene; the wax precipitation point and pour point are mainly affected by the wax; and the solidification point is affected by the wax and asphaltene. The treatment idea of reducing viscosity and inhibiting wax is determined. By compounding the synthetic pour point depressant POA-VA and the viscosity reducer DBD-DOPAMA, the effect of reducing the viscosity and freezing point of crude oil was evaluated. PD-7 (POA-VA 40%, DBD-DOPAMA 50%, and P-10C 10%) system was selected as the optimal formula. When the concentration of the system is 10%, the viscosity reduction rate reaches 95.2%; the freezing point can reduce by 10.2°C; it has good oil sample adaptability, salinity resistance, and temperature resistance; and the oil washing rate can reach more than 60%. The oil displacement system was injected into the formation by means of multiconcentration and multislug and was applied in the field of Luo 321-2 Well. A total of 500 t of the oil displacement system was injected, and the effect of measures lasted for 400 days, with a cumulative oil increase of 883 t. It has been applied in different blocks 30 times and achieved a good field application effect.


2021 ◽  
Author(s):  
Juan Carlos Romero Albino ◽  
Saulo Figliuolo ◽  
Valert Beal ◽  
Luis Alberto Breda Mascarenhas ◽  
Hugo Francisco Lisboa Santos

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Aojiang Qi ◽  
Pinshu Qian ◽  
Hai Huang ◽  
Dazhong Ren ◽  
Xiaoyu Gu ◽  
...  

This paper examines the damage caused by slickwater fracturing fluid to the microscopic pore structure of tight sandstone in the Chang 7 member in the Ordos Basin. A submicron CT in situ displacement system was used to analyze and graphically represent changes in pores in core samples following fracturing fluid damage. The results show the following: (1) the damage caused by slickwater fracturing fluid to tight sandstone fractures mainly occurs in the early stage of fluid incursion. The damage is characterized by a decrease in the effective pore volume, increase in the number of pores, and insignificant subsequent damage. The main causes of pore damage by slickwater fracturing fluid are retention of slickwater in the liquid phase and hydration swelling of clay minerals in the pores. (2) After the high pressure intrusion of slickwater fluid, the pore size of large-size intergranular pores increases, and there is no obvious damage after water flooding. However, fractures and small dissolution pores in the cores are the main areas of fluid retention after fracturing fluid invasion due to their small flowing radius and complex structure. These are the locations where damage mostly occurs.


Author(s):  
João Victor Fabri ◽  
Tiago Vieira da Cunha ◽  
Pablo Andretta Jaskowiak

Author(s):  
Saulo Queiroz Figliuolo ◽  
Valter Estevão Beal ◽  
Luis Alberto Breda Mascarenhas ◽  
Juan Carlos Romero Albino ◽  
Hugo Francisco Lisboa Santos

Abstract Oil well production rate should be maintained during its lifecycle and maintenance interventions are necessary to reach this goal. Production engineer teams work on different ways to make the production stable and to enhance the oil recovery from the reservoirs. However, interventions are necessary to maintain or recover the production rate. Some problems that cause maintenance are malfunctioning/wear of equipment, clogging/obstruction and operational mistakes. These maintenances are required using expensive equipment, especially on offshore operations. In order to reduce the overall cost of interventions, robotic systems have been proposed. In this work, a conceptual development for a robotic production column well intervention system is proposed. This equipment should be strong enough to resist oil well environmental characteristics. Nowadays, the challenge involves high pressure and high temperature wells, high flow rates, a long/deep well and other very hostile features. Even though, this device has to be very slim and lightweight because it will be responsible for carrying on other systems (measurement / inspection tools, completion tools, etc.) displacing into the oil well production column. On the other hand, it needs to have highly efficient power consumption since the power availability is usually limited in the actuation environment of this autonomous equipment. In order to guarantee the achievement of the desirable requirements, the design team followed the best practices of the product development process aided by a design for lifecycle guidelines.


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