Injection valve and method

A valve for selectively closing a flow path through a wellbore in a single direction, the valve comprising:

• a housing;
• a plurality of members configured to form a variable piston surface area across the flow path;
• a flow tube axially movable within the housing between a first and a second position due to fluid flow acting on the variable piston surface, wherein each member in the variable piston surface is attached to the flow tube via a connection member and is rotatable around a circumference of the connection member toward a centerline of the housing to form the variable piston surface area;
• and
• a flapper for closing the flow path through the valve upon movement of the flow tube to the second position.

A method of operating a gas lift well, comprising:

• pressurizing an annular area with gas, the annular area being formed between a production tubing string and a wellbore;
• opening a gas lift valve located in the annulus, the gas lift valve permitting the flow of gas from the annulus to an interior of the production tubing;
• closing the gas lift valve;
• closing a second valve, the second valve having:
• a body;
• a plurality of members configured to form a piston surface across the flow path, each member is attached via a pin member to an end of a shiftable member annularly disposed in the body wherein each member rotates around a circumference of the pin member towards a centerline of the body to form the piston surface;
• and
• a flapper member, the flapper member closable to seal the flow path when the shiftable member moves from a first position to a second position due to fluid flow acting on the piston surface.

22 An assembly for selectively closing in a single direction a flow path between an annular area and the inside of a production tubing string, wherein the annular area is formed between the production tubing string and a wellbore, the assembly comprising:

• a mandrel provided with at least one bore communicating at one end with the outside of the tubing string and at another end with the inside of the tubing string;
• a valve for selectively closing a flow path in a single direction, the valve comprising a housing connected to the mandrel, a plurality of members configured to form a variable piston surface area across the flow path, a flow tube axially movable within the housing between a first and a second position due to fluid flow acting on the variable piston surface area, wherein each member in the variable piston surface is attached to the flow tube via a connection member and is rotatable around an axis that extends through a length of the connection member from an opened position to a closed position toward a centerline of the housing to form the variable piston surface area, and a flapper for closing the flow path through the valve upon movement of the flow tube to the second position;
• and
• a gas lift valve, wherein the gas lift valve communicates with the flow tube through the flapper.