Patent Application
20100096121
The present invention relates generally to brushes, and particularly, to brushes for cleaning the interior surfaces of well bore casings.
When a bore is created by drilling equipment, a casing is typically inserted into the well to reinforce the sides and to provide a secure conduit for equipment and debris. The interior wall of the casing must be kept free of dirt and debris in order to ensure the smooth passage of equipment and exiting debris. After a well is completed, tools must be inserted to check various aspects of the well. These tools often include a brushing tool to clean the inside surface of the casing and remove debris. Because of the harsh environment in which these brushes must operate, the bristle material must be tough and resilient, yet efficient at removing and evacuating debris. These brushes typically include numerous welds to retain the various brush components. In use, these welds have a high failure rate, which causes the brush to fail, potentially damaging the well bore.
Existing designs typically use either steel or nylon brush elements. Common designs include plug-type or row-type inserts. Plug-type inserts generally feature cylindrically-shaped bristle modules that may be inserted into a base piece mounted on a shaft extending through the well bore; see, for example, U.S. Pat. No. 3,176,772. The inserts may be arranged in a spiral pattern around the shaft circumference. Row-type inserts commonly feature several rows of bristles on a base piece that may be mounted to a shaft extending through the well bore. The rows are generally arranged in an angled parallel arrangement around the circumference of the shaft. These designs, however, suffer from several deficiencies. First, the relatively small number of bristles in these designs decreases the brushes' cleaning ability, and the relatively large space between inserts reduces the brushes' ability to evacuate loose debris. Second, the use of multiple bristle inserts increases the time and labor required to replace the bristles. Third, existing designs commonly use carbon steel or nylon bristles, which do not withstand the harsh environment inside the well bore casing for very long. Finally, existing designs are constructed by bonding or crimping individual bristles to the base piece, resulting in the loss of bristles as the brush operates.
A need, therefore, exists for a well bore casing brush that efficiently removes and evacuates debris, is easy to replace, and holds up to the conditions inside the well bore casing.
The invention is directed to a brush for cleaning the inside of a well bore casing. The brush includes a cylindrical base piece, circular retaining members that secure the bristles in a bristle assembly, and channels formed through the bristle assembly to provide an evacuation path for loose debris. The components of the brush are preferably made from stainless steel to resist corrosion. The brush design eliminates the need for structural welds. All structural components are created from solid material, eliminating the possibility of brush failure. The brush is incorporated into the well bore checking tools and is inserted into the well as part of the tools.
Other objects, aspects and advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description, when considered in conjunction with the appended claims and the accompanying drawings briefly described below.
For the purpose of illustrating the invention, there are shown in the drawings embodiments that are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and constructions particularly shown. In the drawings:
Referring now to the drawings, which illustrate several preferred embodiments of the invention, a brush for a well bore casing is shown. As will be discussed in more detail below, the brush preferably includes an inner base ring, at least one bristle assembly circumscribing the outer surface of the base ring, and bristles held in place by the retaining members, forming a brushing area.
The brushing surface has at least one channel 20 formed through it. The channel 20 extends through the width of the brushing surface from a front face or edge 22 to a rear face or edge 23, and preferably extends in a path non-perpendicular to the front face 22. In one embodiment, the channel 20 has the shape of a parallelogram extending helically around the circumference of the brush. As seen in
As shown in
The bristles, like the inner retaining member, retaining ring, and base ring, may be made of any number of materials, but are preferably made from stainless steel for strength and corrosion resistance. The bristles are preferably made from wire with a diameter of approximately 0.010 to 0.035 inch. However, one of ordinary skill in the art will realize that the bristle diameter may be changed to create either stiffer or more flexible bristles; the thicker the wire, the stiffer the bristles will be. Also, the density of the bristles will impact the overall stiffness of the brush. Thus, the bristle density can be controlled so as to vary the stiffness of the brush depending on the anticipated use.
The brush is intended to occupy the space between the tools and the inner surface of the well bore casing. Thus, the length of the bristles will depend essentially on the difference between the diameter of the well bore casing and the diameter of the tools. The bristles preferably have a length so that the diameter of the brush (defined by the radial ends of the bristles) is slightly greater than the inner diameter of the well bore casing. One of ordinary skill in the art will realize that the bristle length will have an effect on the effectiveness of the bristles; longer bristles will deform more easily but will provide a deep channel through which to evacuate debris; shorter bristles will be more rigid and will provide more effective cleaning, but a correspondingly shallower channel. In a preferred embodiment, the bristles extend approximately one inch from the base of the bristle ring; that is, the bristles are preferably formed from wire segments approximately 2 inches long.
The brush is installed on the tools 30 as shown in
The brush is constructed by placing bundles of bristles equally on a circular tool in a teepee-like arrangement. This allows a solid retaining ring 15 to be forced over the bristle bundles until it reaches the approximate center point of the bundles. The inner retaining member 14 is then flared with a tool to force the bristles to fold around the retaining ring. A further folding of the inner member flattens the bristles against the retaining ring and creates the finished bristle ring 13.
As discussed above, the brush features channels extending from one face of the brush to the other. After the bristle ring is created, portions of the bristles are removed to create the channels that allow the debris to move through the brush. Alternatively, the channels may be formed by specific placement of the bristles in the inner retaining member.
It will be apparent to those skilled in the art that various modifications and variations can be made in the configuration of the present invention without departing from the spirit or scope of the invention. It is intended that the present invention cover such modifications and variations provided they come within the scope of the appended claims or their equivalents.
