WELL GAS-LIFT UNIT Russian patent published in 1996 - IPC

FIELD: oil and gas producing industry, particular, methods for oil recovery; applicable in starting and operation of wells by gas-lift method. SUBSTANCE: to increase reliability and efficiency of gas lift, the radial channels of nipple are inclined and, in height of tubing from bottom upward, diameter of each next axial channel nipple is larger than that of the previous one, and distance between next two nipples is larger than the distance between previous two nipples. Lower end of starting and working valves is rigidly connected with landing unit made with through axial channel whose lower end has opposite additional valve. Device has damper in form of hollow cylindrical stepped guide located in the body hollow and bellows for formation in the initial position of gap between body and guide, with gap reduction in the working position when stepped guide moves in body. Installed on valve bodies are cases with seals disconnecting hydraulic communication between internal and external hollows of valves. Valves have additional bellows installed in body. In this case, bellows form airtight neutral chamber together with body. Efficient diameter of additional bellows is less than diameter of gate which is determined by the following relation dPf/dPg = 1-(Db/Dgt)Dgt)², where dPf is range of variation of fluid flow pressure, MPa; dPg is range of variation of injected gas pressure, MPa; Db is effective diameter of bellows, m; Dgt is gate diameter, m. Chamber between bellows is neutral and airtight. Diameter of gate equals that of lower bellows and is larger than diameter of upper bellows, which is determined from the following relation dPf/dPg=(Db/Dgt)Dgt)², where Db is effective diameter of bellows, m. Landing units are made with through slots which accommodate thrust lugs of stop collet which is connected with lower ends of landing units by means of shear pins (screws) or resting on spiral spring. Collet is installed in lower part of ring with lugs upward and internal beads resting from above on shear ring. Stop collet is rigidly connected with lower end of landing unit. EFFECT: higher efficiency. 9 cl, 13 dwg