Patent Application
20110168383
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 for scraping wellbore casing.
2. Description of the Related Art
Wellbore cleaning devices include casing 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 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 scraper blades are not affixed to the central scraping body, but are urged radially outwardly from it by compression springs in order to provide a force for removal of debris. An example of this type of arrangement is found in U.S. Pat. No. 7,311,141 issued to Tulloch et al.
The invention provides methods and devices for cleaning the interior of tubular members, such as casing members. Exemplary non-rotating tubular cleaning devices are described which include a unitary central tool mandrel with a surrounding retainer sleeve which a sleeve body with one or more windows disposed laterally through the body. The exemplary cleaning devices also include one or more cleaning members, such as scraper blades. A working portion of each cleaning member extends from the radial interior of the retainer sleeve through a window and radially outside of the retainer sleeve.
At least one annular support member with an axial separation, i.e., a C-ring, is disposed radially within the retainer sleeve and supports the one or more cleaning members outwardly against the interior radial surface of the retainer sleeve. The C-ring support ring preferably has a shape memory that causes the C-ring cleaning member support ring to bias the cleaning member against the interior radial surface of the retainer sleeve. During operation, if the cleaning member contacts an obstruction in a surrounding wellbore, the support ring can deflect inwardly due to the axial separation.
The construction of scraper devices in accordance with the present invention permit these tools to have improved strength and resistance to axial and torsional forces within the work string within which the scraper device is used. The threaded connection of the tool mandrel to other components in a tool string largely governs the strength of the tool overall.
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 an upper sub 19 and a lower sub 20 which are affixed together by a threaded connection 22. The tool mandrel 12 presents an outer radial surface 24 having a number of different diameter portions. There is an upper, enlarged-diameter portion 26, a middle, reduced-diameter portion, generally shown at 28, and a lower, enlarged-diameter portion 30.
A retainer sleeve 32 radially surrounds the tool mandrel 12. As best seen in
A cleaning member support ring 38 is disposed around the reduced-diameter portion 28 of the tool mandrel 12 and located inside of the retainer sleeve 32. An exemplary support ring 38 is depicted apart from the other components of the scraper device 10 in
When the support ring 38 is disposed radially inside of the retainer sleeve 32, the working portions 47 of the scraper blades 46 extend through the windows 36 of the retainer sleeve 32 and extend radially outwardly beyond the retainer sleeve 32, as can be seen in
Referring again to
Referring now to
It is noted that brushes, magnets or other cleaning members might be used in place of scraper blades 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 production, such as the production of hydrocarbons.
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.
