DEVICE FOR SEALING WELLHEAD ROD OF SUCKER-ROD PUMPING UNIT Russian patent published in 2006 - IPC F04B47/02 

FIELD: oil field equipment; sealing wellhead rod at high wellhead pressure at development of oil fields by water flooding.

SUBSTANCE: provided device has body mounted on wellhead fittings and three seals mounted in body in succession. Lower part of body with first and second (upward) seals on side of high pressure is located in tubing string lowered in well. Cavity of body between these seals is communicated with borehole annulus of tubing string. Cavity of body between second and third seals is communicated with additional reservoir for lubricant. First seal may be made in form of plunger pair. First seal takes up main pressure drop. Insignificant leakage is returned to well through passages connecting the cavity above first seal with annulus and second contact seal working at slight pressure drop is constantly lubricated from additional reservoir.

EFFECT: avoidance of freezing of water in passages in winter season.

2 cl, 2 dwg