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Method of Using a Downhole Welding Tool to Engage a Fish with Limited Engagement Area

IP.com Disclosure Number: IPCOM000241322D
Publication Date: 2015-Apr-16
Document File: 2 page(s) / 358K

Publishing Venue

The IP.com Prior Art Database

Abstract

The vast majority of fishing tools currently available fall into one of two categories, internally or externally engaging tools. They rely on slips or threads to grip the fish and apply sufficient force to pull it free. However, these tools are not effective when the profile of the fish does not allow access to the OD or ID. In these cases, milling is often the only option. This invention allows a fishing BHA to securely engage with a fish with limited or no access to the OD or ID. This is accomplished by welding a tool at the bottom of the workstring directly to the fish. The heat and material for the weld would likely be provided by the highly exothermic thermite reaction. In one embodiment, the weld would be performed through a thermite welding reaction. This process is widely used in the railway industry, and is also hot enough to occur underwater. The components for the reaction are aluminum powder, iron oxide (rust), and a source of high heat. The initial heat is most often provided by the ignition of a magnesium strip. In order to utilize this reaction in a downhole fishing tool, the powder mix could be stored in a bottom section of the tool that is connected to an upper section via shear screws. When the fish is tagged with sufficient force, the shear screws will shear and allow two conductive surfaces to contact. This completes a circuit with a battery, whose current heats up a resistor and ignites a magnesium strip, which begins the thermite reaction (see attachments).The reaction produces molten iron, which flows out of the bottom of the tool and forms a weld with the fish. Flow channels on the bottom of the tool allow for a large weld surface area, which increases the weld strength. Ideally, this tool would be run below a safety joint, which would allow the tool to disengage in the event that the fish could not be pulled. The tool could also incorporate a cutting structure on the bottom surface that could be used to clean up the top of the fish and increase the bond strength at that contact prior to triggering the reaction.

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Method of Using a Downhole Welding Tool to Engage a Fish with Limited Engagement Area

The vast majority of fishing tools currently available fall into one of two categories, internally or externally engaging tools.   They rely on slips or threads to grip the fish and apply sufficient force to pull it free.   However, these tools are not effective when the profile of the fish does not allow access to the OD or ID.   In these cases, milling is often the only option.   This invention allows a fishing BHA to securely engage with a fish with limited or no access to the OD or ID.   This is accomplished by welding a tool at the bottom of the workstring directly to the fish.   The heat and material for the weld would likely be provided by the highly exothermic thermite reaction.

In one embodiment, the weld would be performed through a thermite welding reaction.   This process is widely used in the railway industry, and is also hot enough to occur underwater.   The components for the reaction are aluminum powder, iron oxide (rust), and a source of high heat.   The initial heat is most often provided by the ignition of a magnesium strip.   In order to utilize this reaction in a downhole fishing tool, the powder mix could be stored in a bottom section of the tool that is connected to an upper section via shear screws.   When the fish is tagged with sufficient force, the shear screws will shear and allow two conductive surfaces to contact.   This completes a circ...