| 摘要 |
A pumping apparatus (10) is disclosed which includes a downhole reservoir unit (20), a pumping unit (18) and a power unit (102). The reservoir unit (20) has a piston assembly (70) with a top piston (72) and a bottom piston (74). A storage chamber (82) is defined between the two pistons (72, 74) which is variable in volume as the piston assembly moves from the rest position to a pumping position where a helical spring (98) is compressed. The piston assembly (70) is moved by fluid in a tubing string (22) through reciprocal motion of a pulser piston (48). As the piston assembly (70) is moved downwardly, fluid from the reservoir passes through a check valve into the storage chamber (82). When the piston assembly (70) is in the pumping position, the pulser piston (48) is retracted and the helical spring (98) drives the piston assembly (70) upward. The volume of the storage chamber (82) decreases and fluid is pumped from the storage chamber through the tubing string to the surface. The movement of the pulser piston is controlled by a double acting hydraulic cylinder assembly (30) which has a stroke sufficient to move the piston assembly (70) between the rest and pumping position despite the presence of gas in the fluid in the tubing string (22). The fluid pumped from the reservoir can be used to cool the hydraulic fluid in the hydraulic fluid reservoir (108). |
