Abstract: A single trip whipstock assembly which can be run into a well, set, and operated from a window in the well casing in a single trip includes a milling tool (5) attached to the upper end of a whipstock (6) to the lower end of which is attached a packer (7) or anchor which can be set by appropriate means prior to detachment of the mill from the whipstock to initiate window formation. The packer may be hydraulic and may be set by means of a setting tool (4) located above the mill (5) and connected to the packer by a hose (21). The mill (5) incorporates circulation ports which are initially isolated from the central chamber thereof to permit flow of hydraulic fluid from the setting tool to the hose (21) via the interior of the mill. Once setting has been effected, the hose (21) is severed, permitting the piston of the setting tool to operate a flow diverter within the mill and open the circulation ports to the interior of the tool for subsequent drilling mud circulation during milling operation.

Abstract: A drill string anchor for use in a well bore, the anchor having a body, a through bore and a plurality of anchor assemblies, each assembly comprising an anchor member, a piston supported within a body and a biasing means. The piston is initially radially movable in response to an initiating fluid pressure in the through bore causing its movement from a first retracted position to a second extended position in which the piston drives the anchor member into contact with the wall of the well bore. The biasing means acts to provide a force biasing the piston towards the first retracted position.

Abstract: A drill string component for preventing chafing of a drill casing as a result of contact between the drill casing and a rotating drill string comprises a central mandrel (2) having rotatably mounted thereon a sleeve (11). The sleeve (11) is retained between shoulders defined on the mandrel to prevent accidental loss of the sleeve in the event of excessive wear in the supporting bearings. Axial thrust loads are transferred from the outer sleeve (11) to the mandrel by way of thrust bearings supported on the mandrel shoulders. Seals (24A, 24B) located between the outer sleeve seal bodies (23) and an inner sleeve (9) prevent the ingress of contaminants to the zone of bushings (12, 13) which rotatably support the outer sleeve.

Abstract: An oil well packer retriever has a packer miller (6) which has a series of fin-like blades radiating from a central tube string (2). The blades are faced with tungsten carbide and in use these mill away the packer allowing it to drop by gravity. A packer catcher (7) catches and retains the fallen packer for removal from the well. The weight of the packer held by the catcher (7) bears on a shear collar (8) which is secured to the central string (2) by one or more shear bolts the combined strength of which is known. Should the shear stress on the collar (8) exceed that which has been preselected by the number and/or material of the shear bolts, the bolts shear releasing the collar (8) which drops out of engagement the catcher (7) allowing the retriever to be withdrawn from the packer. The packer retriever can under normal conditions mill out and extract several packers without redressing the blades and replacing the catcher.