Patent Application
20150267499
The field of the invention is annular debris barriers for subterranean use and more particularly barriers that are modular where modules rotationally lock to present flexing segments in each module with gaps that are offset between the modules.
Some subterranean equipment can be installed in boreholes for many years leaving an opportunity for debris to enter open cavities such as annular spaces between two structures that at some point need to move relatively to release or reconfigure the tool. If the debris accumulates in such spaces it has the capability of jamming the tool so that normal release is difficult if not impossible. A failure to normally release could cause the need for extraordinary and expensive measures such as a special trip to mill out the tool. Such measures are expensive and have the potential to cause other problems particularly if the generated debris from milling is not effectively removed with circulation or debris collection equipment that is in the hole.
Various designs for debris barriers have been used. A foam hollow cylinder that is mounted to an inner pipe and moved axially into a narrow annular space defined between an inner and outer tubulars is shown in FIGS. 5 and 6 of U.S. Pat. No. 8,464,787. Snap fit annular rings to go into an open annular space as a debris barrier are shown in U.S. Pat. No. 8,631,863. A foldable annular ring that employs a spring force to collapse for radial extension to protect an annular space between a string stabbed into a seal bore of a packer is shown in U.S. Pat. No. 7,604,048. Barriers that are internal to a tubular are shown in FIG. 4 of WO2013/122589. Another one-piece annular barrier is shown in FIG. 3 of EP 2322758 A2. Articulated tubular wipers that converge around a tubular as the tubular moves through where the wipers can be in single (104A) or multiple (not shown) semi-circular segments is shown in US 2013/0153302. This design is not for debris exclusion but rather is for forcibly scraping off debris from a tubular outer wall as the string is run into the borehole.
What is needed and provided by the present invention is a modular design where each module has a plurality of flexing resilient segments that can be scored or have gaps either when run in or after initial flexing where the gaps are circumferentially offset among the modules and the modules are rotationally locked to each other. The module spacing allows the segments to flex as much as 90 degrees or more before segments in one module contact segments in an adjacent module. The spacing allows fluid movement across the barrier while holding back the debris. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the detailed description and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.
An annularly shaped modular debris barrier can be mounted to an internal or an external member that are spaced apart to define an annular gap that could collect debris. The modules rotationally lock. Modules have circumferential segments that can be initially spaced apart to promote flexing that can occur when there is relative axial movement between the structures that define the annular gap. The gaps between segments are circumferentially offset as between adjacent segments to create a labyrinth through which the fluid can move in opposed direction while at the same time causing the debris to be retained. The segments stay in a flexed condition to exert a contract stress on the free ends thereof that touch the adjacent structure.
The modular assembly 10 can be a stack as shown in
While
Those skilled in the art will appreciate that what has been described is a modular debris barrier that can be used in annular spaces particularly where some relative axial movement is contemplated and where there needs to be an ability to pass flow so that thermal or pressure gradients can be equalized across the assembly. This is to be contrasted with a solid ring design used in the past that can either be a fluid barrier itself by spanning the annular gap or become a barrier after some accumulation of debris around the small clearances or no clearances that it provides. The rotational lock feature ensures that in use the gaps do not line up to produce a straight shot for debris to advance into the annular gap that is to be protected. Additionally if there is to be a milling out of the assembly, the rotational lock facilitates millout by preventing relative sliding between adjacent modules. The barrier can be a solid ring that has gaps placed into it from an edge thereof without going clean through so at one ends there is still a cohesive ring while at an opposed end is spaced extending segments. Alternatively, spaced segments with gaps can be associated with a support ring. In another variation, a solid ring with radial scores or tears can be used to allow additional flexibility of the segments as the other tubular is inserted in the assembly for contact with the segments. The segments are preferably resiliently flexible and compatible with long term exposure to well fluids and are spaced to allow flexing for 90 degrees should well conditions create such a circumstance.
The width of the segments can be uniform or different. In that case different subsets of axially spaced segments may define a labyrinth for flow and debris retention for different sized tubulars that can be positioned in an outer tubular to define different widths for the annular space. Different sized pipes can be accommodated in the annular space with the degree of bending of some or all the segments changing depending on the size of the resulting annular space. The flexing capability of the segments also allows for debris exclusion if the annular space is not symmetrical such as when the inner and outer tubulars that define the annular space are not concentric. The size of the annular space can also vary as connection upsets move past but the flexible nature of the segments tolerates these variation while continuing to keep the debris retained on the outside of all the segments and the modules in which they are disposed.
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:
