Disconnect devices for downhole strings

摘要

A disconnect device comprises a tubular member having a window for receiving an engagement member, and a sleeve having connected and disconnected positions. The engagement member engages with a component of a downhole string to connect the disconnect device to the rest of the string such as through a helically-shaped thread disposed on the engagement member and on the component. The window can comprise at least one wall that is outwardly tapered so as to prevent the engagement member from passing through the window when the tubular member is disconnected from the component of the string. The engagement member is maintained within the window by the sleeve when in its connected position to maintain the connection between the tubular member and the component. When moved to its disconnected position, the engagement member disengages the component by moving inwardly into the bore of the tubular member.