Oil well packer retriever.

摘要

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 under 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 shear strenght 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the bolts shear releasing the collar 8 which drops out of engagement with the catcher 7 allowing the retriever to be withdrawn from the packer.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 re-dressing the blades and replacing the catcher.