Abstract: A downhole well tool is provided which includes a shifting sleeve for opening a flow communication port. The well tool includes first and second primary seal elements positioned upstream and downstream, respectively, of the port as well as upstream and downstream of the threaded connections between the well tool and sections of tubing forming the well flow conduit. A fluid diffuser element may be included to abate flow damage across the primary seal elements during the shifting of the sleeve. A method of selectively transmitting fluid incorporating said well tool also is disclosed.

Abstract: A subterranean well casing float tool has a tubular metal housing which is securable to well casing conduit. A valve is carried within the housing and comprises a frame with a valve head and seat carried relative to the frame and biased toward closed position. A compartment includes the valve head for enclosure around a bias, such as a spring, when the valve head is moved away from the valve seat. The valving components are directly secured to the housing by threads having profiled shear surfaces such that the shear area of the valving members is substantially greater than that of the housing.

Abstract: A subterranean well casing float tool is comprised of a tubular metal housing which is securable to a well casing conduit. Varing means are implaced within the housing, with substantially all of the components of the valving means, save a biasing means, are thermosetting. The valving means has a thermosetting frame and valve head and valve seat means relative to the frame. A biasing member, such as a compressed spring is used for urging the valve head toward the valve seat to a closed position. A compartment including the valve head is provided for enclosure around the biasing means when the valve head is moved fully away from the valve seat to protect the spring from errosive turbulent fluid flow when the valve head is in the open position relative to the seat. The valving means is directly secured to the housing by means of thread members having profiled shear surfaces such that the shear area of the valving means is substantially greater than that of the metal housing.