Abstract: A roller tool 1 that can be connected into a string for deployment into an oil or gas well includes at least two rollers or wheels 10 located on each side of the roller tool 1, with axes of rotation that are perpendicular to the axis of the roller tool 1. The roller tool further includes at least two interconnecting tubular portions, where one tubular portion 41 comprises a mandrel 45 that connects to another tubular portion 42. An annular hub 20 is fitted over the mandrel 45 and the rollers 10 are connected onto the hub 20. The tubular portions 41, 42 comprise circumferential sleeve sections 56a, 56b that partially extend over the rollers 10 and resist detachment of the rollers 10 from the roller tool 1. The roller tool 1 can aid passage of a string through a well by holding the string away from the walls of the well and reducing frictional contact.

Abstract: A connection mechanism (4) comprises first and second components (6, 8) which can be selectively coupled together, one of the first or second components comprises a locking member (25) which is moveable between a first state and a second state, the other of the first or second component comprises means (16) for initially moving the locking member from the first to the second state as the first and second components are initially drawn together and means (19) for returning the locking member to the first state once the first and second components are fully engaged together to prevent disengagement of the first and second components.