| 主权项 |
1. A pump jack system for vertically reciprocating a downhole pump, the system comprising:
a drive cylinder including a drive barrel, a drive piston disposed within the drive barrel, and a drive rod with a lower end affixed to the drive piston, wherein the drive piston includes a fluid passage providing fluid communication across drive piston within drive barrel to create a single drive chamber within the drive barrel; two balance cylinders positioned on either side of the drive cylinder, each balance cylinder including a balance barrel, a balance piston disposed within the balance barrel, and a balance rod with a lower end affixed to the balance piston, wherein an upper balance chamber and a lower balance chamber within each balance barrel are separated by each balance piston, wherein the lower balance chambers are in fluid communication; an upper cross member operatively connecting an upper end of the drive barrel and an upper end of each of the balance barrels; a lower cross member operatively connecting a lower end of the drive barrel and a lower end of each of the balance barrels; and a rod cross member operatively connecting an upper end of the drive rod and an upper end of each of the balance rods in a fixed configuration, wherein the rod cross member is configured for lifting the balance pistons upon upward movement of the drive piston. |
