1¡¢It is not necessary to keep different pressure between inside and outside of tubing string for packer releasing, therefore, no matter does water flow regulator have an open or closed stopcock, the packer can be released. This decreases the amount of suppression of a fishing closed stopcock and a mud truck. Thus, this packer can be widely used due to its simple operating process.
2¡¢An original structure is used in flushing piston hole packing. It has an advanced feature of repetitive sealing of flush well.
3¡¢It has a protective rubber packing element, high pressure-bearing and a long service-life.
