Devices and Methods for Severing a Tube-Wire |
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申请号 | US13538410 | 申请日 | 2012-06-29 | 公开(公告)号 | US20140000895A1 | 公开(公告)日 | 2014-01-02 |
申请人 | John Gordon Misselbrook; | 发明人 | John Gordon Misselbrook; | ||||
摘要 | A shear pig assembly and method of use for severing a linear conductor within a surrounding tubular. A shear pig assembly includes a main body and a nose that radially surround the linear conductor within the tubular. The main body and nose are axially moveable with respect to each other to cause a shear plug to move radially within a shearing chamber, thereby severing the linear conductor. | ||||||
权利要求 | What is claimed is: |
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说明书全文 | 1. Field of the Invention The invention relates generally to systems and methods for severing a tube-wire or similar transmission conductor that is disposed in a surrounding tubular. 2. Description of the Related Art Coiled tubing has become a popular means for running a bottom hole assembly (“BHA”) into a subterranean wellbore. A wireline or tube-wire is sometimes run inside of the coiled tubing when realtime downhole data is required, such as during directional drilling or logging. Tube-wire is a tube that contains an insulated cable that is used to provide electrical power and/or data to the bottom hole assembly or to transmit data from the BHA to the surface. Tube-wire is available commercially from manufacturers such as Canada Tech Corporation of Calgary, Canada. In the event that coiled tubing and the associated BHA become stuck in the wellbore, it is common practice to pump a ball or plug down through the coiled tubing in order to disconnect the BHA from the coiled tubing. If this fails to free the coiled tubing, then the contingency is to kill the well, cut the coiled tubing at the surface, and run a chemical cutter on wireline down through the coiled tubing in order to retrieve the coiled tubing from the well. If this problem occurs with TeleCoil, then it is necessary to retrieve the tube-wire before running the chemical cutter. The tube-wire in a TeleCoil string is comparatively weak compared to conventional braided cable, and using a tensile shear release mechanism in the BHA for the tube-wire is considered unreliable. Accordingly, the TeleCoil BHA incorporates a ball operated tube-wire release mechanism to facilitate retrieval of the tube-wire. There is no contingency available in the event of a failure of this mechanism. Conventional drop bars and “go devil” devices that are used to sever slickline rely upon gravity to be delivered to a point wherein they can sever the slickline. They are unsuitable for use in horizontal or deviated wellbores. The invention provides devices and methods for severing a tube-wire proximate the BHA of a coiled tubing run BHA. The devices and methods described are useful in the event that the coiled tubing becomes stuck within the surrounding wellbore. An exemplary shear pig assembly is described that radially surrounds the tube-wire and is axially moveable along it. The exemplary shear pig assembly includes a main body portion and a nose. The nose may be affixed to the main body portion by a frangible connector. A shear chamber is formed between the main body portion and the nose, and a shear plug is disposed within the shear chamber. The exemplary shear pig assembly also includes a fin array that radially surrounds a shaft of the main body portion to help propel the shear pig assembly through the flowbore of the running string. To actuate the shear pig assembly to sever the tube-wire, the shear pig assembly is moved downwardly along the tube-wire to a predetermined location wherein it is desired to sever the tube-wire. When the shear pig assembly reaches this point, the nose of the cutting assembly encounters a contact fitting within the running string which stops the downward movement of the shear pig assembly. The shear pig assembly is preferably so moved by pumping fluid into the coiled tubing running string at the surface. In particular embodiments, the shear pig assembly has a relatively short axial length that will permit it to negotiate coiled tubing that is wrapped around a reel at the surface. When the nose of the shear pig assembly contacts the contact fitting, the frangible connector is ruptured. The main body of the shear pig assembly is moved axially toward the nose causing the shear chamber to collapse axially. This collapse causes the shear plug to move radially within the shear chamber. In this embodiment, the tube-wire is severed between the shear plug and the nose as well as between the shear plug and the main body. Once severed, the tube-wire can be withdrawn from the running string. The advantages and further aspects of the invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein: An exemplary shear pig assembly 26, which has been constructed in accordance with the present invention, is shown radially surrounding the tube-wire 24 within the running string 18. The shear pig assembly 26 is axially moveable along the tube-wire 24 and is preferably propelled downwardly through the flowbore 22 of the running string 18 by fluid pressure, as will be described in further detail shortly. The exemplary shear pig assembly 26 is shown in greater detail in Also in particular embodiments, an annular fin array 46 radially surrounds the shaft 32 between the enlarged diameter portion 42 and the flange 44. The fin array 46 preferably includes a plurality of angled fins 48 or cups that are shaped to receive and contain fluid pumped from the surface 14. In particular embodiments, the fin array 46 is formed of polyurethane or a similar resilient material. In preferred embodiments, the fins 48 of the fin array 46 extend radially outwardly to contact the surrounding running string 18. The nose 30 of the pig assembly 26 radially surrounds the distal end 36 of the shaft 32. An o-ring fluid seal 50 provides a fluid seal between the nose 30 and the shaft 32. A frangible connector in the form of a shear pin 52 preferably secures the nose 30 to the shaft 32. The nose 30 also preferably presents a distal end 54 having an annular angled surface portion 56. A generally wedge-shaped shearing chamber 58 is defined axially between the nose 30 and the shaft 32. The shearing chamber 58 is wedge-shaped due to the presence of the angled face 38 of the shaft 32 and an oppositely-angled interior face 60 that is presented by the nose 30. A shear plug 62 is retained within the shearing chamber 58. The shear plug 62 is generally cylindrical with a first angled surface 64 that is complimentary to the angled face 38 of the shaft 32 and a second angled surface 66 that is complimentary to the angled face 60 of the nose 30. A central passage 68 is disposed through the shear plug 62, and the tube-wire 24 passes through the passage 68. In operation, the coiled tubing 18 and the BHA 16 are used to remove obstructions from the wellbore 10. In the event that the BHA 16 becomes stuck in the wellbore 10 and conventional methods for freeing the BHA 16 fail, the shear pig assembly 26 can be used to sever the tube-wire 24 proximate the BHA 16. In one embodiment, illustrated in Alternatively, the coiled tubing 18 could be cut at surface 14 to expose the tube wire 24. A launching assembly (not shown) of a type known in the art would then be attached to the coiled tubing 18. The shear pig assembly 26 would be guided over the tube-wire 24 and pushed into the launching assembly. A pack-off (not shown) would be installed around the tube-wire 24 at the top of the launching assembly. A pump (not shown) is then hooked up to the launching assembly and then the shear pig assembly 26 can be pumped down the coiled tubing 18 in the wellbore 10. Once the shear pig assembly 26 has been launched or pumped through the reel 70, it will be located within the flowbore 22 of the coiled tubing 18, as illustrated in Those of skill in the art should understand that the exemplary shear pig assembly 26 described herein could be used in other situations wherein it is desired to sever a linear conductor other than tube-wire within a surrounding tubular other than a coiled tubing running string. Such alternative linear conductors might include slickline, light cable or small tubing. The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention. |