Patent Application
20130032330
The field of the invention is debris barriers for annular gaps that are defined by relatively moving members and more particularly where the debris barrier snap mounts and self centers while acting as a bearing when the members move to possible a non-concentric relationship during relative movement.
Debris barriers are used to prevent particulate buildup in confined spaces that could subsequently impede or prevent operation of other equipment or subsequent relative movement between close fitting components that need to move relatively at some later time. Some applications have no relative movement and the debris barrier is there to isolate equipment such as a liner hanger. Once the hanger is set the debris barrier can be pulled out with the running tool that delivered the liner. On example of this type of annular barrier is shown as item 54 in US Publication 2010/0032167.Another is item 7 in US Publication 20110108266.
Debris barriers can also be placed on whipstocks to keep the whipstock anchor below free of debris as illustrated in U.S. Pat. No. 6,308,782. Debris barriers can be associated with slips so that slip extension energizes a debris barrier such as 34, 164 in U.S. Pat. No. 6,302,217. Annular barriers can be retracted during run in and extended at a desired location with axial compression as with barrier 30 in WO 2008/063979. Debris barriers can be inflatable structures such as item 92 in US Publication 2009/0283330. Debris barriers can temporarily block a tubular string as in item 150 in US Publication 2009/0090518. Applications using sliding sleeves employ debris barriers such as 30b in U.S. Pat. No. 7,032,675. Seals for sliding sleeves are also made from packing material made of continuous carbon fiber in item 30a in the latter patent. On a larger scale such as in a boiler application there are debris barriers internal to the boiler as in item 10 of U.S. Pat. No. 6,581,667.
One such valve that has relatively moving exposed parts to wellbore debris is the RB Isolation Valve offered by Baker Hughes Incorporated, components for which are shown in U.S. Pat. No. 7,210,534 and US Publication 2011/0114324.
What is needed and provided by the present invention is a debris barrier that can exclude most solids from an annular space defined by relatively moving components that might not maintain concentricity during relative movement. The barrier is preferably snap fit and sufficiently loosely mounted so as to enable it to shift and center itself as the shape of the annular space that it blocks changes. It is preferably made of continuous carbon fiber so that it has similar expansion properties as the tubulars that define the annular space where the barrier is mounted. It functions as a bushing using its lubricious properties should the shape of the annular space change due to the tubulars moving out of a concentric relationship. The barrier has an external groove to retain some of the small particles that get between the barrier and the outer tubular that defines the annular space. The part can be made using tight tolerances to maintain very small clearances upon assembly, which is helpful for the exclusion of the solids. The groove can be internal.
Those skilled in the art will have a greater understanding of the invention from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is determined from the appended claims.
A debris barrier snap fits to a tubular groove of one of the tubulars that define the annular gap in which the barrier is to be mounted. It is loosely mounted so that it can center itself in the annulus as the relatively moving members go out of a concentric arrangement. The continuous carbon fiber material used for the debris barrier has lubricious qualities to act as a bushing when the annulus shape changes due to movement of the tubulars out of a concentric relationship. An outer groove on the barrier acts to trap and retain small particles that manage to advance between the barrier and the outer tubular. The snap fit is accomplished with flexible spaced apart fingers with grip surfaces to engage a groove on one of the tubulars.
As shown in
As seen in
Groove 42 located on the exterior of the barrier 10 and near end 20 works as a capture location for small debris that gets past end 20 to get the debris out of the way so that relative sliding motion of the tubulars 12 and 14 can continue despite some infiltration of solids into the annular space between barrier 10 and the surrounding tubular 12 and to prevent debris from getting further into the internal workings of the tool. Groove 42 can be an interior groove.
The same concept can also be employed on tubular 14 as shown in
The small clearance between parts is the primary mode of debris exclusion using the barrier 10.
The objective is to provide sufficient flexibility to allow surface 38 to expand to jump over surface 36 during assembly. A discrete finger structure is not necessary. A cylindrical shape can simply be notched or cut clean through such as with wire EDM to give the resulting cylindrical shape a spring like functionality so that assembly is facilitated. After assembly there would be enough potential energy to keep the surface 28 from moving out radially beyond surface 30 although in the preferred embodiment the presence of tubular 12 over the barrier 10 that had previously been snap fit to tubular 14 should in and of itself be sufficient to keep end 22 in groove 32 while allowing relative movement between tubulars 12 and 14.
The barrier 10 can itself have grooves internally or externally beyond the groove 42 and for the same purpose but a limit exists on the number of grooves that can optionally be used since the structural integrity of the barrier 10 can be affected.
Those skilled in the art will appreciate that the barrier 10 has the beneficial qualities of easy snap in mounting while also having a loose enough fit to self align if the two relatively moving tubulars that define the annular gap in which the barrier 10 is mounted can move to positions where they are not concentric. The barrier 10 serves as a bearing or bushing of sorts taking advantage of the properties of the continuous carbon fiber, which is the preferred material. Other lubricious materials that can withstand the downhole conditions can be used such as Teflon®, for example. A preferred material is continuous carbon fiber in a thermoplastic composite such as PEEK matrix that has excellent non-galling and non-seizing characteristics. The barrier has features that allow some entering debris to be retained in a groove or grooves in the barrier itself where very fine particles can collect. Screens or threads are other alternatives to the groove or grooves. As another option there can be holes in the groove or grooves to allow a washing out of some of the debris so it does not build up in the groove. The use of a finger structure to mesh with projections on the tubular to which the barrier is mounted will also minimize or eliminate relative rotation between the barrier and the tubular that supports it. Rotational locking of the debris barrier 10 is optional. Web sections 34 are there primarily to lend strength to the tubular 14 that has a fairly thin wall thickness.
Although the barrier 10 is shown mounted to tubular 14 where it is exposed to debris in passage 50, the barrier 10 can be secured to tubular 12 at an end 52 and snap connect to tubular 12 in the same manner as described above for tubular 14.
Item 12 slides with respect to item 14 without normal contact. They are not locked to each other.
When mounted, the barrier 10 preferably floats in a tight clearance application and in a confined mounting location. Despite thermal loads the barrier 10 can continue to function by aligning itself while held in place to continue to exclude debris.The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
