Velocity-tubing pressure actuated subsurface safety valve

Abstract

A subsurface safety valve which is used to control the flow of well fluids through well tubings combines (1) the velocity valve principle of differential pressure and (2) a change in well tubing pressure to produce a closing force for the valve. A valve housing is connected into a well production tubing. A movable valve element is connected to the valve housing. In one position of the valve element flow of fluids through the valve housing is permitted and in another position thereof flow of fluids through the valve housing is prevented. The movable valve element forms with the valve housing a pressure chamber and larger and smaller differential areas. An inwardly protruding surface or flow bean is formed on the valve element. Fluids flowing through the valve housing cause a pressure differential across the flow bean. The flow bean is located between the larger and smaller differential pressure areas, the larger being above and the smaller below the flow bean. The flow bean is sized relative to the sizes of the differential pressure areas in any particular flow system so that the differential pressure across the flow bean is below that required to overcome the tubing pressure forces holding the valve open under normal flow velocity conditions. However, the valve closes upon increased flow velocity above normal flow velocity because of the increased differential pressure across the flow bean and decreased tubing pressure on the larger differential pressure area.