| 摘要 |
A downhole chock absorber reduces or eliminates fluid and gas pound in a pumping system employing a well pump mounted at the bottom of a sucker rod string. A substantially cylindrical coupling has coaxial, internally threaded upper and lower segments. The lower segment is screwable onto a complementary, externally threaded, upper end of a member of the sucker rod string. A shaft with a complementary externally threaded lower end is screwed into the internally threaded upper segment of the coupling. A plurality of diametric holes are vertically displaced and sequentially, circumferentially offset along the upper portion of the shaft. A spring slidably, coaxially disposed on the shaft below the holes is seated on the coupling. The spring has an outer diameter less than the outer diameter of the coupling to reduce the possiblity of the spring wearing against the pump system production line tubing. Several pins, one for each of the holes, are snugly disposed through the holes and protrude beyond the circumference of the shaft at both ends. Each of the pins is preferably a flexibly resilient spiraled coil of steel. A cylinder slidably disposed on the shaft is seated on the spring. The cylinder is longer than the length of the portion of the shaft extending above the coupling less the compressed length of the spring. The cylinder has at least one relief port which lies above the shaft when the spring is compressed to its elastic limit. The cylinder also has two vertical slots aligned with each of the pins with opposite ends of the pins protruding into their respective pair of slots. The pins slide reciprocally in the slots. The slots are long enough that the upper end of each slot does not engage its respective pin when the spring is fully compressed but the lower end of each slot does engage its respective pin when or after the spring is fully expanded. The cylinder also has an internally threaded upper end which screws onto a complementary threaded lower end of a member of the sucker rod string disposed above the cylinder. The spring biased shaft and cylinder absorb the forces transmitted to them through the sucker rod string members to which they are attached. The closer the shock absorber is mounted to the pump, where fluid and gas pound are initiated, the greater the protective value of the shock absorber. If the elastic limits of the spring are exceeded and the spring damaged, the shock absorber can easily be pulled with the sucker rod string, the pins popped out of the shaft, the cylinder removed and the spring replaced.
|
