The present invention relates to wellbore tools and methods for retrieving metal debris, such as cuttings and other metal objects, that may be formed by milling downhole objects, by unintentionally dropping an object in a wellbore, or by intentionally releasing a portion of a tool to fall in the well and subsequently be removed. More specifically, the tool of the present invention utilizes magnetic forces to attract ferrous metal debris, so that the tool effectively captures the debris and may then be retrieved to the surface from the wellbore.
When drilling an oil or gas well, or when refurbishing an existing well, normal operations may result in various types of metal debris in a well. Downhole milling produces cuttings which often are not completely removed by circulation. Other metallic objects may drop into and collect near the bottom of the well, or on intermediate plugs placed within the well.
Methods have been used to circulate fluids up the annulus at a rapid rate and thereby carry debris upward, with expectations that the debris will then settle into the basket for retrieval when circulation is reduced. Some basket tools utilize a venturi action to drawn debris into the tool.
Other tools utilize magnets mounted within a housing for being lowered into the well. Some tools practically may be limited to retrieving cutting since magnetization is only at the bottom of the tool. Other tools utilize a plurality of magnets aligned in cavities near the outer surface of the tool. Each magnet may be recessed in the tool body. Exposed magnets are subject to physical damage during the process of cleaning debris from the well. Conventional metal debris retrieving tools are relatively expensive, and it is difficult or impossible to effectively clean and change out the magnets of most tools in the field.
U.S. Pat. No. 6,655,462 discloses magnets within an interior of a rotatable protective sleeve. U.S. Pat. Nos. 6,216,787, 6,308,781, and 6,491,117 disclose magnetic tools and magnet protectors for deflecting a striking force on the magnets. U.S. Pat. No. 6,439,303 discloses the retainer caps for mounting each of a plurality of magnets within a recess in the tool body. Publication 2001/4013413 discloses in one embodiment a magnet which covers substantially the entire surface of the tool body. Other patents of interest include U.S. Pat. Nos. 2,089,724, 2,709,104, 2,729,494 and 2,918,323, 3,905,631, 4,226,285, 5,178,757, 5,453,188, 5,944,100, 6,269,877, and 6,629,562.
The disadvantages of the prior art are overcome by the present invention, and an improved magnetic retrieval tool and method are hereinafter disclosed for retrieving debris from a well.
In one embodiment, a tool for suspending in a well to retrieve ferrous metal debris from the well includes an elongate tool body having a plurality of circumferentially arranged slots. Each slot has a radially outward portion with a circumferential width less than a circumferential width of a radially inward portion. A plurality of magnets may be positioned in each slot, and one or more stop rings, such as centralizers, used for axially retaining the plurality of magnets in the slots. Each of the stop rings is removable from the tool body, thereby allowing removal of the plurality of magnets from the plurality of the slots in a field operation.
In a preferred embodiment, the tool body includes a central bore for pumping fluid through the tool body, and the upper end of the tool body is configured for attaching to a tubular extending into the surface. The outer surface of each centralizer has an effective diameter greater than the outer surface of the plurality of magnets.
In one embodiment, each of the plurality of slots has substantially a dovetail configuration, while in another embodiment, each of the plurality of slots has a substantially T-shaped configuration. Each of the plurality of magnets in substantially enclosed within a magnet carrier, with the non-ferrous carrier having an outer configuration for slidably fitting within a respective one of the plurality of slots. In one embodiment, each magnet has a substantially cylindrical configuration, and the carrier is formed from one of stainless steel, aluminum and a high wear plastic material.
According to the method, a tool body is provided with a plurality of slots as discussed above, and magnets are positioned within each slot and are held in place by one or more stop rings removable from the tool body. The tool with the magnets may then be positioned in the well for collecting and subsequently retrieving metal debris.
A significant feature of the invention is that the magnets are reliably held within the tool body, yet may be easily removed from the tool body in a field operation for repair or cleaning.
Yet another feature of the invention is that the tool protects each magnet within a magnet carrier which slides within a respective slot.
A significant advantage of the tool and method is that the tool may be used and easily cleaned and repaired in a field operation.
These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures of the accompanying drawings.
As shown more clearly in
The magnets may be provided in elongate carrier strips, and
Returning again to
A non-ferrous magnet carrier 26 formed from the base plate 30 and the side and top protector 32 at least substantially encloses each of the respective magnets 16. This enclosure is highly desired to protect the magnets from foreign objects external of the tool, since the magnets otherwise may strike objects in the well and fracture or otherwise become damaged. Carrier 32 separates the tool body 12 and the magnets by providing a non-ferrous magnet carrier between the sides of each slot and each magnet. Most importantly, the carrier formed from the base plate 30 and the protector 32 may be easily slid from the respective slot in the tool body at the surface, and disassembled, cleaned, and if necessary repaired at the well site. The base plate 30 may be removed from protector 32, then the magnets 16 each removed from its respective pocket within protector 32. As shown in
A tool 10 retrieves ferrous metal debris from a well, and includes an elongate tool body 12 having a plurality of circumferentially arranged slots 14 each for receiving a plurality of magnets. One or more stop rings 18 retain the plurality of the magnets within the slot. Each stop ring is removable from the tool body, thereby allowing the removal of the plurality of the magnets from the plurality of slots. According to the method, the tool is provided with the slots and the magnets, and is suspended in a well to retrieve various metal debris.
The magnetic tool as disclosed above includes a single stop ring 18, which may easily be removed from the tool body. Depending on the desired axial length of the magnets throughout the length of the tool, and in part depending upon the maximum allowed travel length of the farthest magnet to its exit point on the tool, more than one stop ring may be provided. A plurality of carrier 26 are preferably provided in each slot. Each axially spaced stop ring may be removable from the tool body so that magnets may slide out of their respective slots and into the cavity formed when the stop ring is removed. Depending on the number and configuration of the stop rings provided along the tool body, it may be desirable to position stabilizers or centralizers above, below, and possibly between the magnets to provide protection to the metal object attracted to the magnets.
In a preferred embodiment, the stop ring may comprise a centralizer with a plurality of ribs having an outer surface spaced outward from the magnets, thereby providing protection to objects attracted to the outer surface of the tool. The centralizer may be rotatably fixed to the tool body or may be rotable on the tool body. If desired, bearings may be provided to allow the centralizer to more easily rotate on the tool body.
The term “stop rings” as used herein is intended to mean a substantially ring-shaped member which fits on the tool body and axially secures the carrier strips and the magnets therein on the tool body. The stop ring may be completely circular, or in other configurations may be substantially C-shaped to satisfy the purpose as disclosed herein.
In the embodiment depicted, the upper end of the tool body 12 is configured for receiving a tubular for suspending the tool body in the well, and for passing fluid through a central bore in the tool body. In other embodiments, the tool may be configured for connection to a wireline, or to another type of tubular for suspending the tool in the well.
Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alternations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.
Number | Name | Date | Kind |
---|---|---|---|
2709104 | Gibbs | May 1955 | A |
2729494 | Trowbridge | Jan 1956 | A |
2918323 | Coffee | Dec 1959 | A |
3089724 | Crooks | May 1963 | A |
3637033 | Mayall | Jan 1972 | A |
3905631 | Ricks et al. | Sep 1975 | A |
4226285 | Moseley, Jr. | Oct 1980 | A |
5178757 | Corney | Jan 1993 | A |
5453188 | Florescu et al. | Sep 1995 | A |
5454943 | Ashton et al. | Oct 1995 | A |
5944100 | Hipp | Aug 1999 | A |
6216787 | Ruttley | Apr 2001 | B1 |
6269877 | Zeer et al. | Aug 2001 | B1 |
6308781 | Ruttley | Oct 2001 | B2 |
6354386 | Ruttley | Mar 2002 | B1 |
6357539 | Ruttley | Mar 2002 | B1 |
6439303 | Sorhus et al. | Aug 2002 | B1 |
6491117 | Ruttley | Dec 2002 | B2 |
6629562 | Fidan | Oct 2003 | B1 |
6655462 | Carmichael et al. | Dec 2003 | B1 |
20010013413 | Ruttley | Aug 2001 | A1 |
20030159834 | Kirk et al. | Aug 2003 | A1 |
20050184611 | Rinholm et al. | Aug 2005 | A1 |
Number | Date | Country | |
---|---|---|---|
20060011346 A1 | Jan 2006 | US |