With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flood...With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flooding experiment videos as the data source. The results of the new method were verified through comparing with the manual measurement data.On this basis, the dynamic changes of the three-phase contact angles under flow conditions were clarified by the contact angles probability density curve and mean value change curve. The results show that, for water-wetting rocks, the mean value of the contact angles is acute angle during the early stage of the water flooding process, and it increases with the displacement time and becomes obtuse angle in the middle-late stage of displacement as the dominant force of oil phase gradually changes from viscous force to capillary force. The droplet flow in the remaining oil occurs in the central part of the pore throats, without three-phase contact angle. The contact angles for the porous flow and the columnar flow change slightly during the displacement and present as obtuse angles in view of mean values, which makes the remaining oil poorly movable and thus hard to be recovered. The mean value of the contact angle for the cluster flow tends to increase in the flooding process, which makes the remaining oil more difficult to be recovered. The contact angles for the membrane flow are mainly obtuse angles and reach the highest mean value in the late stage of displacement, which makes the remaining oil most difficult to be recovered. After displacement, the remaining oils under different flow regimes are just subjected to capillary force, with obtuse contact angles, and the wettability of the pore throat walls in the microfluidic model tends to be oil-wet under the action of crude oil.展开更多
本文中数字电流表的控制系统采用AT89S51单片机,A/D转换器采用ADC0809为主要硬件,实现数字电流表的硬件电路与软件设计。该系统的数字电流表电路简单,所用的元件较少,成本低,调节工作可实现自动化。数字电流表可以测量0~200 m A的8路输...本文中数字电流表的控制系统采用AT89S51单片机,A/D转换器采用ADC0809为主要硬件,实现数字电流表的硬件电路与软件设计。该系统的数字电流表电路简单,所用的元件较少,成本低,调节工作可实现自动化。数字电流表可以测量0~200 m A的8路输入电流值,并在LCD液晶显示屏上显示出来。展开更多
基于磁通门电流传感器、精密电阻、20 bit SAR型A/D转换器和树莓派设计了量程范围为10~1000 A的高精度交直流电流表.通过硬实时Linux内核和迭代Hampel滤波器等技术规避了树莓派在硬件实时性上的缺点,充分发挥其在运算能力和可拓展性方...基于磁通门电流传感器、精密电阻、20 bit SAR型A/D转换器和树莓派设计了量程范围为10~1000 A的高精度交直流电流表.通过硬实时Linux内核和迭代Hampel滤波器等技术规避了树莓派在硬件实时性上的缺点,充分发挥其在运算能力和可拓展性方面的优势,实现了在误差范围不超过±0.02%的前提下,具有测试数据存储、导出、远程连接、程序迭代便捷等特点.此外,从设计原理上对整套测量系统进行理论误差估计,证明了其能够达到0.02%的测量精度.展开更多
基金Supported by National Science and Technology Major Project of China (51674271)Major Technical Field Test of PetroChina (2019F-33)。
文摘With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flooding experiment videos as the data source. The results of the new method were verified through comparing with the manual measurement data.On this basis, the dynamic changes of the three-phase contact angles under flow conditions were clarified by the contact angles probability density curve and mean value change curve. The results show that, for water-wetting rocks, the mean value of the contact angles is acute angle during the early stage of the water flooding process, and it increases with the displacement time and becomes obtuse angle in the middle-late stage of displacement as the dominant force of oil phase gradually changes from viscous force to capillary force. The droplet flow in the remaining oil occurs in the central part of the pore throats, without three-phase contact angle. The contact angles for the porous flow and the columnar flow change slightly during the displacement and present as obtuse angles in view of mean values, which makes the remaining oil poorly movable and thus hard to be recovered. The mean value of the contact angle for the cluster flow tends to increase in the flooding process, which makes the remaining oil more difficult to be recovered. The contact angles for the membrane flow are mainly obtuse angles and reach the highest mean value in the late stage of displacement, which makes the remaining oil most difficult to be recovered. After displacement, the remaining oils under different flow regimes are just subjected to capillary force, with obtuse contact angles, and the wettability of the pore throat walls in the microfluidic model tends to be oil-wet under the action of crude oil.
文摘基于磁通门电流传感器、精密电阻、20 bit SAR型A/D转换器和树莓派设计了量程范围为10~1000 A的高精度交直流电流表.通过硬实时Linux内核和迭代Hampel滤波器等技术规避了树莓派在硬件实时性上的缺点,充分发挥其在运算能力和可拓展性方面的优势,实现了在误差范围不超过±0.02%的前提下,具有测试数据存储、导出、远程连接、程序迭代便捷等特点.此外,从设计原理上对整套测量系统进行理论误差估计,证明了其能够达到0.02%的测量精度.
