Patent Application
20110186287
1. Field of the Invention
The invention relates generally to systems and methods for cleaning the interior of tubular members. In particular aspects, the invention relates to methods and devices used for constructing and assembling scrapers or other cleaning devices for cleaning wellbore casing.
2. Description of the Related Art
Wellbore cleaning devices include casings scrapers and brushing devices. These mechanisms are used to remove mud, cement sheath, perforation burrs, rust, scale, paraffin, and other debris from the internal surface of wellbore casing. The casing scraper or brush is typically attached to a drill string for operation. The drill string and cleaning device are then disposed within the casing members to be scraped, and rotated.
Typical casing scrapers include a central scraping body and one or more scraping is blades that extend radially outwardly therefrom. Conventional casing scrapers generally fall into one of two categories: rotating and non-rotating. With a rotating scraper, the scraping body and the scraping blades are securely affixed to each other so that both rotate with the drill string. In applications where the drill string is rotated for long periods of time, rotating scrapers can cause serious wear and damage to the interior surface of casing. With a non-rotating scraper, only the scraping body rotates with the drill string.
The invention provides an improved wellbore cleaning device and a device for use in assembling such a cleaning device. A cleaning device in the form of a scraper device is described which includes stabilizers and a scraper assembly with a plurality of scraper blades. These components preferably rotate about a central tool mandrel. The tool mandrel presents a radially outer surface having an axially-facing stop shoulder. In the described embodiment, the stabilizers and scraper assembly are attached onto the tool mandrel between the stop shoulder and an attaching ring assembly which locks into a groove on the tool mandrel.
In exemplary embodiments, the attaching ring assembly includes an annular housing and a plurality of locking wedges that can be moved radially inwardly and outwardly with respect to the housing. The locking wedges are disposed within an inner radial surface of the housing and are radially separated from one another by gaps in an unlocked condition. In one embodiment, compression springs are disposed between the is housing and the locking wedges to bias the locking wedges radially inwardly toward a locked configuration. In an alternative embodiment, translation screw arrangements are used to translate the locking wedges radially inwardly with respect to the surrounding housing.
In addition, one or more removable threaded screws are used to draw the locking wedges radially outwardly against the housing and into an unlocked condition whereby the attaching ring assembly can be easily slid onto or off of one axial end of the tool mandrel. The one or more threaded screws may be removed to permit the locking wedges to snap into the groove on the tool mandrel, thereby securing the stabilizer and scraper assembly components onto the tool mandrel.
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:
Preferably, the tool mandrel 12 is made up of a unitary mandrel body 20 and presents an outer radial surface 22 having a number of different diameter portions. There is a lower, enlarged-diameter surface portion 24 which presents an upwardly facing stop shoulder 26. A reduced diameter surface portion 28 lies adjacent the stop shoulder 26. A recess 30 is further provided within the central area of the reduced diameter surface portion 28. In addition, a groove 32 is located within an upper portion of the reduced diameter surface portion 28.
A number of components are retained upon the tool mandrel 12 in a manner so that they are rotatable with respect to the tool mandrel 12. A lower stabilizer 34, of a type known in the art, is disposed around the reduced diameter surface portion 28 of the tool mandrel 12 and positioned against the shoulder 26. Bearings 36, such as roller or needle bearings of types known in the art, are used to allow ease of rotation for the stabilizer 34 about the mandrel 12.
A scraper assembly, generally indicated at 38, is positioned upwardly of the lower stabilizer 34. The scraper assembly 38 may have any of various known configurations. In the depicted embodiment, the scraper assembly 38 includes a retaining sleeve 40 having windows 42 through which scraper elements 44 protrude. The scraper elements 44 are typically biased radially outwardly to protrude through the windows 42 by compression springs (now shown), in a manner known in the art.
It is noted that brushes, magnets or other cleaning members might be used in place of scraper elements 44 to create a cleaning device in accordance with the present invention. It can be seen that the present invention provides a cleaning device that is useful for cleaning tubular members and wellbores that are often used in subterranean fluid is production, such as the production of hydrocarbons.
An upper stabilizer 46 surrounds the tool mandrel 12 above the scraper assembly 38. Like the lower stabilizer 34, the upper stabilizer 46 is provided with bearings 48 which allow for ease of rotation for the stabilizer 46 about the tool mandrel 12.
An attaching ring assembly 50, in accordance with the present invention, is used to secure the various components surrounding the tool mandrel 12 upon the mandrel 12.
An exemplary attaching ring assembly 50 is shown apart from the other components of the scraper assembly 38 in
The attaching ring assembly 50 preferably secures the components 34, 38 and 46 axially between the ring assembly 50 and the shoulder 26. The attaching ring 50 includes an annular ring housing 52 having an outer radial surface 54 and an inner radial surface 56. A number of spring recesses 58 are disposed within the inner radial surface 56 of the housing 52. In addition, several openings 60 are disposed through the housing 52.
Several arcuate locking wedges 62 are located within the housing 52. In the depicted embodiment, there are four locking wedges 62. However, there may be more or fewer than four such wedges, if desired. It is noted that there are arcuate gaps or separations 64 located between each of the adjacent wedges 62 when the ring assembly 50 is in the unlocked condition shown in
In the unlocked condition, a threaded screw 76 is inserted through each opening 60 of the housing and into the threaded blind bore 74 of a neighboring wedge 62. The threaded screws 76 are tightened within the bores 74 to cause each of the wedges to be drawn radially outwardly until the springs 72 are compressed and the outer radial surfaces 66 of the wedges 62 are maintained in contact with the inner radial surface 56 of the housing. In this unlocked condition, the inner radial surfaces 68 of the wedges 62 are expanded to their maximum amount, and the diameter of clearance for the inner radial surfaces 68 of each locking wedge 62 is maintained to be larger than the outer diameter of the upper axial end 15 of the tool mandrel 12. The attaching ring assembly 50 may be to easily slid onto or off of the upper axial end 15 of the tool mandrel 12 in the unlocked condition.
In order to secure the attaching ring assembly 50 to the tool mandrel 12, the attaching ring assembly 50 is slid onto the tool mandrel 12 over the upper axial end 15 (as shown by the phantom position 50a in
Then, the threaded screws 76 are removed from the threaded blind bores 74 and openings 60, thereby freeing the locking wedges 62 from their attachment to the housing 52. The compression springs 72 will urge the wedges 62 radially inwardly so that they will snap into a locking engagement within the groove 32 of the tool mandrel 12, as shown in
It will further be understood that the compression springs 72 and the translation screw assemblies 80 both serve as mechanisms to urge the locking wedges 62 radially inwardly with respect to the housing 52.
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.
