Patent ID: 7861790
Filing Date: 2011-01-04
Classification: E21B

Abstract:
1. A valve for selectively closing a flow path through a wellbore in a first direction, the valve comprising: a body; a plurality of members configured to form a piston surface across the flow path, each member is attached via a pin member proximate an end of a shiftable member annularly disposed in the body, wherein each member rotates around an axis that extends through a length of the pin member from an opened position to a closed position 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, wherein the shiftable member in the first position blocks the flapper member from closing and wherein the shiftable member is biased in the first position by a biasing member disposed between the body and the shiftable member.