Rotary Shoe Direct Fluid Flow System

Abstract

The circulation system for a rotary shoe features a fluid diversion to a peripheral zone from which the flow is directed by tubes or housing bores to the vicinity of the cutting structure to improve cooling and removal of debris. Some of the fluid is directed straight through into the mandrel of the tool being milled. If the formation below is at low pressure a packer cup is added to the grip tool attached to the shoe at one end and to the fish at the other end. A swivel is used to prevent the packer cup rotation. Fluid diverted by the packer cup comes up out of the mandrel and into an annular space between the mandrel and the inner wall of the shoe and out from under the shoe by flowing past the cutters. Fluid loss to the formation is minimized and cooling and cutting removal is enhanced.

Description

FIELD OF THE INVENTION[0001]The field of the invention is subterranean milling and more particularly where the mill washes over the stuck object such as a packer and has a fluid distribution system directed at the cutting structure with a seal option in the packer mandrel to control fluid loss during milling.BACKGROUND OF THE INVENTION[0002]Milling shoes are mills with peripheral cutters that descend over an object to be milled such as a packer as the cutting progresses. The cutting structure takes out the packer seal assembly as well as any slip assembly and extrusion barriers. The packer mandrel, or innermost structural member that supports a packer sealing element and slip assembly and which can be a part of an assembly of parts generally referred to as the packer body, is straddled by the hollow center of the shoe as the shoe descends as the cutting progresses, as shown in FIGS. 7-10. Pumped fluid to cool the cutting structures is delivered through the hollow core of the shoe as...

AI Technical Summary

Benefits of technology

The circulation system for a rotary shoe in this patent improves cooling and removes debris by diverting fluid to the peripheral zone and directing it to the cutting structure using tubes or housing bores. Some of the fluid is directed straight through into the tool being milled. A packer cup is added to the grip tool attached to the shoe and the fish for low-pressure formations. A swivel is used to prevent the cup from rotating. The fluid diverted by the packer cup comes up out of the mandrel and into an annular space between the mandrel and the inner wall of the shoe, improving cooling and cutting removal while minimizing fluid loss to the formation.

Problems solved by technology

More recently when components have been fabricated or formed from much harder metals the technique of depending on the annular path between the mandrel and the inside wall of the shoe proved more troubling due to the longer mill times and the additional heat generated from trying to mill the harder materials.

Such fluid stream that was intended to come back to the area where the cutters are mounted through the annular space between the mandrel and the inner wall of the rotating shoe could be lost downhole and therefore would be unavailable for cooling the cutting structures and removal of debris.

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