Bi-directional fluid loss device and method

A fluid loss device, for use in a well, comprising:

• a flapper,
• a valve seat adapted to form an interface with a first surface of the flapper, the interface adapted to hold pressure from above the flapper;
• and
• a support capable of contacting at least a portion of a second surface of the flapper in response to pressure from below the flapper;
• the interface adapted to hold pressure from below the flapper in cooperation with the support,
• wherein the flapper has a non-uniform thickness around its periphery, and the support has support surfaces shaped to mate with and provide suoport to areas around the periphery of the flapper,
• wherein the support surfaces each contact the flapper over from about 30 degrees to about 90 degrees of its periphery.

A fluid loss device for use in a well, comprising:

• a flapper,
• a valve seat adapted to form an interface with a first surface of the flapper, the interface adapted to hold pressure from above the flapper;
• and
• a support capable of contacting at least a portion of a second surface of the flapper in response to pressure from below the flapper;
• the interface adapted to hold pressure from below the flapper in cooperation with the support,
• wherein the flapper has a non-uniform thickness around its periphery, and the support has support surfaces shaped to mate with and provide support to areas around the periphery of the flapper,
• wherein the support surfaces each contact the flapper over about 60 degrees of its periphery.

A fluid loss device for use in a well, comprising:

• a flapper,
• a valve seat adapted to form an interface with a first surface of the flapper, the interface adapted to hold pressure from above the flapper,
• a support capable of contacting at least a portion of a second surface of the flapper in response to pressure from below the flapper,
• the interface adapted to hold pressure from below the flapper in cooperation with the support,
• a flapper carrier positioned below the flapper, having the valve seat on an upper surface, and having a port adapted to allow fluid communication from above the flapper to below the flapper, and
• an opening prop slidably carried within the carrier and movable to a first position closing the carrier port, and to a second position opening the port.

A method of operating a fluid loss device in an oil well, comprising:

• positioning a flapper into contact with a valve seat forming a flapper valve seat interface on a first side of the flapper,
• applying a force to the valve seat urging the valve seat into contact with the flapper and the flapper into contact with a support on a second side of the flapper,
• holding pressure across the interface from the first side to the second side, and
• using fluid pressure from the first side of the flapper to apply a force to the valve seat, whereby the ability of the flapper to hold pressure from the first side is increased as the pressure from the first side is increased.

A method of operating a fluid loss device in an oil well, comprising:

• positioning a flapper into contact with a valve seat forming a flapper valve seat interface on a first side of the flapper,
• applying a force to the valve seat urging the valve seat into contact with the flapper and the flapper into contact with a support on a second side of the flapper,
• holding pressure across the interface from the first side to the second side, and
• contacting only selected peripheral portions of the flapper with the support, the selected peripheral portions comprising less than the flail circumference of the flapper.

A method of operating a fluid loss device in an oil well, comprising:

• closing a flapper valve to isolate fluid above the flapper from fluids below the flapper valve,
• providing a pressure equalization flow path from above the flapper valve to below the flapper, the flow oath comprising a valve, and
• opening the flow path valve to substantially equalize pressure above and below the flapper,
• wherein the flapper valve comprises a flapper and a flapper carrier and the fluid loss device comprises an opening prop slidably carried in the flapper carrier, further comprising:
• forming a port through a wall of the flapper carrier, the port forming part of the fluid equalization flow path;
• closing the port with the opening prop in a first position;
• and,
• moving the opening prop to a second position and thereby opening the port.