Oil well pump

Abstract

A pump recovers viscous fluid from a well area defined by a casing extending downwardly into the well. The pump includes a stationary sleeve disposed within the casing and a tubing disposed within the sleeve and reciprocatable upwardly and downwardly within the sleeve and defining a first closure within the sleeve near its bottom end. A first member is disposed on the tubing in slidable relationship to the tubing and a second member is disposed within the sleeve in co-operative relationship with the first member to define a first valve having open and closed positions. The first and second members are disposed above the first closure to define a pump chamber with the first closure. The tubing is spaced from the sleeve above the first valve to define a storage chamber with the first valve. Means define a second valve with the sleeve at a position below the first valve and have open and closed positions. Such means are responsive to the downward movement of the tubing to become opened for providing for a flow of fluid into the pump chamber through the second valve from a position below the second valve. At least one port may be provided in the tubing at a position co-operative with the first member for defining with the first member a third valve having open and closed positions. The third valve may be operable in the open position near the end of the downward movement of the tubing to provide for the passage of fluid from the storage chamber into the pump chamber near the end of such downward movement of the tubing. This prevents fluid pound in the upward movement of the tubing. Means may also be included in the pump for draining fluid from the storage chamber and the pump chamber during the downward movement of the tubing.