Annular flow shifting device

A wellbore cleanup tool collects debris when moved in one direction downhole. A flow diverter is extended for such flow diversion when debris is collected. When running the tool in the opposite direction in the wellbore, the flow diverter is in whole or in part articulated to retract so as to reduce resistance to fluid that passes around the outside of the tool. A segmented diverter can have fixed and movable components that are guided. The movable components can become longitudinally offset from the fixed components for movement in the direction where maximum flow bypass around the outside of the tool is desired. In an alternative embodiment, the diverter segments can all be movable on an inclined track to retract against a bias force for fluid bias with movement of the tool in the opposite direction allowing the bias to push the segments on the inclined track for diversion of debris laden fluid into a capture volume in the tool.

FIELD OF THE INVENTION

The field of this invention is wellbore cleanup tools and more particularly to flow diverting devices that direct well fluids into the tool for cleanup.

BACKGROUND OF THE INVENTION

Wellbore cleanup tools typically have a mandrel with a screen around it so as to define an annular space in between for accumulation of debris collected from the wellbore. Typically, some fluid diversion device is supported from the mandrel so that in at least one direction of movement of the tool, there is flow into the annular space and through the screen leaving the debris trapped in the annular space. The flow diverter can be fixed or movable with a movable design illustrated in U.S. Pat. No. 6,607,031 where one or more cup seals are illustrated. Some diverters block the flow totally such as one or more stacked cup seals while other designs just severely impede flow around the outside of the tool when directing flow into the annular space.

Since the cleanup of well fluids with these tools principally occurs with movement in a singe direction, it is desirable to get the tool to move at maximum speed in the opposite direction where no or very little capturing of debris actually occurs. The problem occurs with diversion devices that maintain wellbore wall contact in both directions, such as cup seals. For example, if the tool is designed to direct well fluids into the annulus behind the screen when being pulled out of the hole, when the tool is run into the hole, the cup seals still resist fluid movement past them even though they are deflected from the wellbore wall. When this happens, the speed with which the tool can be run into the wellbore is reduced or a risk develops of pressurizing the formation when running in the tool. This can occur when the insertion speed displaces fluid at a faster rate than fluid can bypass the cup seals. Building pressure on the formation can reduce its productivity while slowing the tool speed creates needless expense in operating expenses for surface personnel.

What is needed is a solution that allows delivery of the tool without speed restrictions while when the movement is reversed proper diversion of debris laden fluid into the annular space between the mandrel and the screen regardless of the design of the flow diverter. Several solutions are explored to this problem that focus on simple construction that will stand up to the downhole environment. These and other aspects of the present invention will be more clear to those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings with the claims spelling out the full scope of the invention.

SUMMARY OF THE INVENTION

A wellbore cleanup tool collects debris when moved in one direction downhole. A flow diverter is extended for such flow diversion when debris is collected. When running the tool in the opposite direction in the wellbore, the flow diverter is in whole or in part articulated to retract so as to reduce resistance to fluid that passes around the outside of the tool. A segmented diverter can have fixed and movable components that are guided. The movable components can become longitudinally offset from the fixed components for movement in the direction where maximum flow bypass around the outside of the tool is desired. In an alternative embodiment, the diverter segments can all be movable on an inclined track to retract against a bias force for fluid bias with movement of the tool in the opposite direction allowing the bias to push the segments on the inclined track for diversion of debris laden fluid into a capture volume in the tool.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1is a schematic view of a wellbore cleanup tool10that has a mandrel12surrounded by a screen14to define an annular space16between them for the purpose of accumulation of capture debris. A diverter assembly18is preferably made of segments20and22that circumferentially alternate on a support sleeve24as shown inFIG. 5. One group of the segments such as20can be rigidly mounted to sleeve24while the other group22can be slidably mounted for relative axial movement to an axially aligned position inFIG. 2and an axially misaligned position inFIG. 1. When running into the hole the group22components are pushed uphole with respect to the mandrel12that is being run downhole. As a result the segments22are pushed on their guides to go axially uphole as the fluid represented by arrow24exerts an uphole force due to the descending mandrel12. Fluid flow24moves around the outside of the tool10in the annular space26by coursing through the circumferential gaps between stationary segments20formed by the uphole displacement of the segments22. After clearing past the segments20the fluid stream24simply makes a slight dog leg of a turn and goes between the circumferential gaps between displaced segments22formed because the segments20are not movable axially with respect to the advancing mandrel12to the extent that such gap can close.FIG. 1illustrates that the tool10can be run into the wellbore28at a rapid rate because well fluids can quickly get by around the tool10in the annulus26by following a path first between segments20that didn't move much or at all and then making the necessary turns to get between segment22that have shifted up with respect to mandrel12to open a flow path having reduced resistance and thereby allowing rapid movement of the tool10downhole without creating formation pressure below it. The perspective view ofFIG. 6also illustrates these concepts.

When the tool10is moved in the opposite direction which is out of the wellbore28a flow in the direction of arrow30is induced and that pushes the segments22back into axial alignment with segments20. This movement substantially closes off the annular space26around the tool10and directs fluid flow behind the segments20and22that are now axially aligned and into annulus16where the debris32is screened out and the remaining fluid passes through the screen14as the tool10is pulled from the wellbore28.FIG. 7illustrates these concepts.

In the preferred embodiment, the segments20and22are sections of wire brush to get debris off the wellbore wall28as the tool10is pulled out of the hole. The segments can have gaps between the wire strands but in the aggregate they can fulfill the purpose of acting as a flow diverter when the segments are aligned. While in the preferred embodiment the segments are alternated between stationary and movably mounted, other patterns can be used between movable and stationary segment to allow or impede flow in the annulus26. Other construction is envisioned for the segments apart from wires as long as the purpose of blocking and allowing annulus flow are accomplished. The segments can be made of solid blocks of material compatible with well operating conditions. Rather than segments, a unitary diverter is envisioned that can be retracted when the mandrel moves in one direction and extended when the movement direction is reversed. Segments that spread circumferentially rather than axially are also envisioned as illustrated inFIGS. 8 and 9. Segments may be on a scroll that rolls up when moved up an inline away from the wellbore28and rolls out to close off the annular space when advanced down that same incline.FIGS. 3 and 4are schematic enough to illustrate this concept.

Segments can retract on a slope in a circumferentially abutting or/and overlapping position even while moving axially relatively to each other and then get pushed down that slope while still abutting and/or overlapping until circumferential contact with the wellbore wall is made. Thus despite a growth in diameter as the segments are advanced down a slope they still can substantially obstruct the annular space26when brought into contact with the wellbore28.FIGS. 3 and 4are schematic enough to illustrate this concept. InFIG. 3, the segments or overlapping scroll40is retracted on incline42as the mandrel44is brought down into the wellbore28. This clears the annulus26for flow46to bypass the segments40while pushing against a bias48which can be a spring. When the direction of motion of the mandrel44is reversed, the spring48along with induced flow50push the segments or scroll40back down inclined surface42until the annular space26is closed and the flow50can be substantially redirected into annulus16and then through the screen14.