Abstract: A wellbore cleaning system provides a relockable shearing swivel tool that can be used in tandem with a lockable weight set circulation tool. Suspended from an upper drill string is an assembly consisting of a landing sub, the lockable weight set circulation tool and relockable shearing swivel tool are located immediately above a liner top and from which is suspended a lower drills string. The lower drill string and production liner are both significantly smaller in diameter than the upper drill string and production casing such than when fluid is pumped at high rates through the entire drill string and reduced cross sectional area of the lower drills string and production liner causes a large pressure drop characterized at surface by a high pump pressure. As part of the method, an operator makes up a drill string assembly that includes an upper drill string, a lower drill string, a landing sub or device, the lockable weight set circulation tool, and the relockable shearing swivel tool.

Abstract: A downhole milling tool (100) operable to remove unwanted debris from an interior wall of a pipeline, well casing or other tubular in which the tool (100) is deployable. The tool (100) comprises a hollow tool body (1, 11) mountable on a drill string and an annular element (8) mountable about an outside surface of the tool body (1). The annular element (8) houses at least one elongate milling blade (12). The at least one milling blade (12) is configured such that it always projects from an outside surface of the annular element (8) and includes an elongate cutting face (36). The annular element (8) is configured to be rotatably coupled to the tool body (1) in an active state and rotatably decoupled from the tool body (1) in an inactive state such that the annular element (8) and the tool body (1) are rotationally dependent when coupled and rotationally independent when decoupled.

Abstract: A wellbore cleaning system provides a relockable shearing swivel tool that can be used in tandem with a lockable weight set circulation tool. Suspended from an upper drill string is an assembly consisting of a landing sub, the lockable weight set circulation tool and relockable shearing swivel tool are located immediately above a liner top and from which is suspended a lower drills string. The lower drill string and production liner are both significantly smaller in diameter than the upper drill string and production casing such than when fluid is pumped at high rates through the entire drill string and reduced cross sectional area of the lower drills string and production liner causes a large pressure drop characterized at surface by a high pump pressure. As part of the method, an operator makes up a drill string assembly that includes an upper drill string, a lower drill string, a landing sub or device, the lockable weight set circulation tool, and the relockable shearing swivel tool.

Abstract: A downhole milling tool (100) operable to remove unwanted debris from an interior wall of a pipeline, well casing or other tubular in which the tool (100) is deployable. The tool (100) comprises a hollow tool body (1, 11) mountable on a drill string and an annular element (8) mountable about an outside surface of the tool body (1). The annular element (8) houses at least one elongate milling blade (12). The at least one milling blade (12) is configured such that it always projects from an outside surface of the annular element (8) and includes an elongate cutting face (36). The annular element (8) is configured to be rotatably coupled to the tool body (1) in an active state and rotatably decoupled from the tool body (1) in an inactive state such that the annular element (8) and the tool body (1) are rotationally dependent when coupled and rotationally independent when decoupled.