The flapper valve assembly can be used in series to provide collapsible closures in a drill pipe. Thus, when work strings are withdrawn through the flapper valve, it will close in a conventional manner. However, when the work string must be reinserted through the closed flapper, a collar holding the flapper in its closed position can be sheared from its position within the assembly housing.
The present invention generally relates to controlling the flow of fluids in a wellbore. In one aspect, a valve for selectively closing a flow path through a wellbore in a first direction is provided. The valve includes a body and a piston surface formable across the flow path in the first direction. The piston surface is formed at an end of a shiftable member annularly disposed in the body. The valve further includes 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. In another aspect, a valve for selectively closing a flow path through a wellbore in a single direction is provided. In yet another aspect, a method for selectively closing a flow path through a wellbore in a first direction is provided.
In accordance with the teachings of the present invention, a system and method for forming a seal within tubing is provided. A section of tubing is installed in a borehole. The tubing has an inflatable element disposed along an inner surface of the tubing. The inflatable element is predisposed to expand inwardly under fluid pressure. A fluid pressure is applied to the inflatable element using a tool within the tubing, and the inflatable element is expanded to form a seal within the tubing.
