Patent ID: 9181783
Filing Date: 2015-11-10
Classification: E21B,F04B

Abstract:
1. A sucker-rod pump for deployment in a well liquid in a well bore comprising: a pump chamber; a cylinder; a reciprocating hollow plunger inside the cylinder, the plunger defining a bottom; an injection valve at the bottom of the plunger, the injection valve being configured to interact with the pump chamber; a suction valve at the bottom of the pump chamber; a bypass defining a first hole being connected with the pump chamber and a second hole configured to be connected with the well bore; and a check valve in the bypass, the check valve including a valve member having positive buoyancy in the well liquid, and a seat between the valve member and the second hole, the valve member being configured to come into, and out of, contact with the seat, wherein the cylinder defines a first inner diameter in a cylinder part above the bypass, and a second inner diameter in a cylinder part below the bypass, the second inner diameter being larger than the first inner diameter.