Patent Application
20190211646
This application uses technology disclosed in U.S. Pat. No. 9,381,702 issued 5 Jul. 2016, the disclosure of which is incorporated by reference.
None.
The subject matter discussed in this section should not be assumed to be prior art merely as a result of its mention in this section. Similarly, a problem mentioned in this section or associated with the subject matter provided as background should not be assumed to have been previously recognized in the prior art. The subject matter in this section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.
It is often desired to isolate certain sections of well casing lining a wellbore, the well being used to extract, for example, natural gas or oil. Isolation plugs can be positioned at suitable locations within the well casing, such as by a drill string, and secured in place.
One type of isolation plug is a fracking/bridge plug typically having a pair of segmented slip rings on either side of an expandable seal. The slip rings can be expanded to securely engage the well casing by, for example, the movement of slip rings spreaders located between the expandable seal and the slip ring. The slip rings can have pins, teeth, fins or other projections extending from the outer surface of the slip rings to firmly engage the well casing to prevent the movement of the plug. The slip rings are typically made of materials, such as cast-iron, or carbon fiber, or glass reinforced plastics, which can be milled and drilled when they need to be removed.
A simplified summary is provided herein to help enable a basic or general understanding of various aspects of exemplary, non-limiting implementations that follow in the more detailed description and the accompanying drawings. This summary is not intended, however, as an extensive or exhaustive overview. Instead, the sole purpose of this summary is to present some concepts related to some exemplary non-limiting implementations in a simplified form as a prelude to the more detailed description of the various implementations that follow.
A slip ring is used as a part of a downhole tool placeable within a well casing. The slip ring is comprised of multiple slip ring segments. The slip ring segment includes a stack of fabric layers, the fabric layers comprising fibers, the stack having first and second surfaces, and stitching passing through the stack. The stitching includes first stitching portions passing through the stack, and second stitching portions connecting selected first stitching portions and extending along the first and second surfaces. The slip ring segment also includes a matrix binding the stack of fabric layers and the stitching, and optionally well casing-engaging elements extending from the first surface.
The slip ring segment can include one or more the following. The fabric layers can include one or more of carbon fiber and glass fiber. The second stitching portions can include substantially straight segments without knots, crimps or loops. The stitching can conform to ASTM D6193, 205 hand stitching. The first and second surfaces and the fabric layers can be substantially un-deformed by the stitching. The first and second surfaces can be curved surfaces substantially co-radial to one another. The first stitching portions can be substantially parallel to one another. The first stitching portions can be radially extending stitching portions. At least a portion of the second surface can be at an angle to the first surface. The well casing-engaging elements can extend to positions between the first and second surfaces. At least one of the first and second surfaces can include an axially tapered portion; the axially tapered portion can be formed from the fabric layers prior to resin encapsulation.
Other features, aspects and advantages of technology disclosed can be seen on review the drawings, the detailed description, and the claims, which follow.
The included drawings are for illustrative purposes and serve only to provide examples of possible structures and process operations for one or more implementations of this disclosure. These drawings in no way limit any changes in form and detail that may be made by one skilled in the art without departing from the spirit and scope of this disclosure. A more complete understanding of the subject matter may be derived by referring to the detailed description and claims when considered in conjunction with the following figures, wherein like reference numbers refer to similar elements throughout the figures.
The following description will typically be with reference to specific structural embodiments and methods. It is to be understood that there is no intention to-be limited to the specifically disclosed embodiments and methods but that other features, elements, methods and embodiments may be used for implementations of this disclosure. Preferred embodiments are described to illustrate the technology disclosed, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a variety of equivalent variations on the description that follows. Unless otherwise stated, in this application specified relationships, such as parallel to or substantially parallel to, perpendicular to or substantially perpendicular to, straight or substantially straight, un-deformed or substantially un-deformed, aligned with, or in the same plane as, mean that the specified relationships are within limitations of manufacturing processes and within manufacturing variations. When components are described as being coupled, connected, being in contact or contacting one another, they need not be physically directly touching one another unless specifically described as such. Like elements in various embodiments are commonly referred to with like reference numerals.
In this example first, upper surface 30 and second, lower surface 32 are curved, generally co-radial surfaces, that is having generally the same center of curvature, with first stitching portions 26 being straight segments without knots, crimps or loops. First stitching portions 26 extend radially with respect to the first and second curved surfaces 30, 32. The first stitching portions 26 can deviate from a purely straight, radial character typically as a result of small deflections of the needle used during the stitching operation. Accordingly, the first stitching portions 26 can be considered to be substantially straight with a substantially radial orientation within the limitations of manufacturing processes and within manufacturing variations.
The second stitching portions 28 joining adjacent first stitching portions 26 are created so they are parallel to the first, upper surface 30 and the second, lower surface 32. At least a majority of second stitching portions 28 are substantially perpendicular to first stitching portions 26. The stitching preferably conforms to ASTM D6193, 205 hand stitching pattern. The stitching can be carried out in the manners discussed in U.S. Pat. No. 9,381,702. By creating the stitching in the manner disclosed in this patent, the upper and lower surfaces 30, 32 can be substantially un-deformed so that in terms of fabric deformation, the upper and lower surfaces 30, 32, as well as the intervening fabric layers, are not substantially crimped by the stitching. This ensures that the fibers comprising the fabric layers are not distorted or displaced from their alignment with the respective surfaces.
Stitched stack of fabric layers 24 is encapsulated with a matrix, which binds the layers 20 and pins 34, which when cured creates slip ring segments 14 of
The current technology provides for slip ring segments which can be drillable and millable to permit them to be removed from the well casing when no longer needed. Use of matrix encapsulated fabric layers provides for an extremely strong slip ring segment. The stitching effectively prevents separation of fabric layers 20 by the inner ends 38 of pins 34 when the slip ring segments are driven against the well casing with sufficient force to drive pins 34 into the well casing. When sections of the well are pressurized, the slip rings experience a high interlaminar shear load, often in excess of hundreds of thousands of pounds. Without the presence of the stitching, this interlaminar shear load would be carried primarily by the matrix material between fabric layers, which is substantially weaker than the fabric layers. With stitching, the stitching fibers distribute the shear forces throughout the fabric layers, substantially increasing the shear loading capacity of the slip ring segments.
In some examples the fabric layers 20 at the first, outer surface 30 could be made long enough so it acts as the outermost fabric layer 20 for a series of slip ring segments 14 created using a row of closely spaced forms 22. Such a construction could be useful in mounting the slip ring segments 14 to the remainder of the plug 10.
In some examples it may be desired to have the second, inner surface 32 of the slip ring segments 14 taper axially relative to the first, outer surface 30 to accommodate the structure used to force the split rings against the well casing. This can be done at various times during the manufacture, including trimming the fabric layers 20 so they decrease in both length and width as suggested by the broken lines 44 in
The above descriptions may have used terms such as above, below, top, bottom, over, under, et cetera. These terms may be used in the description and claims to aid understanding what is being disclosed and not used in a limiting sense.
While implementations of the technology are disclosed by reference to the preferred embodiments and examples detailed above, it is to be understood that these examples are intended in an illustrative rather than in a limiting sense. It is contemplated that modifications and combinations will occur to those skilled in the art, which modifications and combinations will be within the spirit of the technology disclosed and the scope of the following claims.
Any and all patents, patent applications and printed publications referred to above are incorporated by reference.
