Plunger gas lift is the main technology in gas recovery by water drainage in the Changqing gas province, Ordos Basin. However,
the existing plunger device can be hardly locked by using the locking device in the highly deviated hole section, so this technology can only be used in vertical wells, but not in such horizontal wells especially with highly deviated hole trajectory. At present, there are over 1200 horizontal gas wells in the Changqing gas province and the problem of liquid loading emerges gradually. In this paper, with the plunger being structurally integrated with the bottom hole assembly (BHA), a dynamics theory model was built and discussed. Then, based on the structural characteristics of horizontal gas wells, a new self-buffered plunger device suitable for horizontal gas wells was designed independently so that the plunger gas lift technology can be used for the gas recovery by water drainage in horizontal gas wells. This device can be run into the highly deviated or horizontal hole section at the bottom of horizontal wells, and simplifies the BHA of those existing plunger devices. This plunger device is composed of a plunger body and an impact-resistant assembly. The plunger body is used to ensure fluid lifting efficiency, and the impact-resistant assembly is used to realize the self-buffered landing impact. As demonstrated
in testing under working conditions, this new device meets the requirements of safe operation of the plunger and prevents the landing
impact of the plunger from destroying the string and the plunger body. Having being successfully put into operation in the Changqing gas province, this device was proved successfully to smooth out the difficulties of drainage gas recovery in horizontal gas wells, with good impact-resistant performance meeting the demands of field application, and with remarkable application results both in great reduction
of wellbore liquid column height and increase of gas production.