Method and apparatus for washing a borehole ahead of screen expansion

Information

  • Patent Grant
  • 6568472
  • Patent Number
    6,568,472
  • Date Filed
    Friday, December 22, 2000
    24 years ago
  • Date Issued
    Tuesday, May 27, 2003
    21 years ago
Abstract
The invention provides apparatus and methods for washing a wellbore ahead of an expansion swedge and radially expanding a sand-control screen jacket in a subterranean well. The methods and apparatus can be used in either the bottom-up or top-down direction and can accomplish borehole washing and screen expansion in a single trip.
Description




TECHNICAL FIELD




The present inventions relate to an apparatus and methods for washing a borehole in a subterranean wells and for expansion of a radially expandable sand-control screen in the borehole.




BACKGROUND OF THE INVENTIONS




The control of the movement of sand and gravel into a wellbore has been the subject of much importance in the oil production industry. The introduction of sand materials into the well commonly causes problems including, plugged formations or well tubings, and erosion of tubing and equipment. There have therefore been numerous attempts to prevent the introduction of sand and gravel into the production stream. One sand control method includes the placement of a radially expandable screen assembly in the borehole.




Another problem in the art is the flow resistance often encountered at the wall of the hole, commonly referred to as the “skin factor”. The skin factor at the wall of the wellbore must often be reduced before a sand-control screen assembly is installed in the formation. It is known in the art to reduce skin factor by washing the wellbore with a fluid chosen for well and formation conditions. Washing procedures also function to flush loose sand, cuttings and other debris from the borehole. The washing is performed in a trip downhole separate from the one or more trips needed for installing and expanding the screen jacket assembly. Each trip downhole requires additional time and expense.




Due to the aforementioned problems, a need exists for improved apparatus and methods for reducing skin factor in a wellbore and expanding a radially expandable sand-control screen jacket assembly in the well.




SUMMARY OF THE INVENTIONS




The present invention relates to an apparatus and method for washing a subterranean well borehole and radially expanding a screen assembly therein. The apparatus comprises a radially expandable screen assembly, a washing assembly adjacent the screen assembly for washing the borehole annular space, and an expansion assembly for radially expanding the screen assembly. The washing assembly can include a washing assembly housing having a wall defining an interior passage, a wash port through the housing wall for providing fluid communication between the interior passage of the washing assembly and the borehole annular space, and a flow control element affixed to the washing assembly housing for substantially preventing fluid flow along the screen annular space. The apparatus can include a force generator, preferably hydraulically powered by the washing fluid, for operating the expansion assembly. The expansion assembly can include a radially expandable swedge. The method of expanding the screen may be in the downhole or uphole direction.




The apparatus can further comprise a return flow passage providing fluid communication between an area of the borehole downhole from the expansion assembly to an area of the borehole uphole from the expansion assembly. The return flow passage can include closeable return ports, and a relief valve.











BRIEF DESCRIPTION OF THE DRAWINGS




The accompanying drawings are incorporated into and form a part of the specification to illustrate several examples of the present inventions. These drawings together with the description serve to explain the principals of the inventions. The drawings are only for the purpose of illustrating preferred and alternative examples of how the inventions can be made and used and are not to be construed as limiting the inventions to only the illustrated and described examples. The various advantages and features of the present inventions will be apparent from a consideration of the drawings in which:





FIG. 1

is a longitudinal cross-sectional view of apparatus and steps in methods of washing the annular borehole ahead of expanding a radially expandable sand-control screen jacket in accordance with the present invention;





FIG. 2

is a longitudinal cross-sectional view of apparatus and steps in methods of using the invention;





FIG. 3

is a longitudinal cross-sectional view of another embodiment of apparatus and methods of the invention; and





FIG. 4

is a longitudinal cross-sectional view of an embodiment of apparatus and methods of the invention.











DETAILED DESCRIPTION




The present inventions are described by reference to drawings showing one or more examples of how the inventions can be made and used. In these drawings, reference characters are used throughout the several views to indicate like or corresponding parts.




In the description which follows, like or corresponding parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the invention. In the following description, the terms “upper,” “upward,” “lower,” “below,” “downhole” and the like, as used herein, shall mean in relation to the bottom, or furthest extent of, the surrounding wellbore even though the wellbore portions of it may be deviated or horizontal. The term “longitudinal” shall be used in reference to the orientation corresponding to the upward and downhole directions. Correspondingly, the “transverse” orientation shall mean the orientation perpendicular to the longitudinal orientation.




Referring broadly to

FIGS. 1-3

, the general structure and methods of using the expansion assembly


10


utilizing the present inventive concepts is shown. A radially expandable screen jacket assembly


12


is deployed into the production zone


14


of a wellbore


16


. It should be understood that the screen jacket assembly


12


may be connected to a casing at either end (not shown), in the conventional manner. When differentiating between the expanded and unexpanded states of the screen jacket assembly, the illustrations carry the designations


12




a


, referring specifically to the unexpanded screen jacket assembly, and


1




2




b


, referring specifically to the expanded screen jacket assembly. The sand-control screen jacket assembly


12


may be comprised of one or more concentric inner and outer screens (not shown) with or without a layer of pre-packed sand (not shown) between screens. The screen jacket assembly


12


may optionally have a screen shroud (not shown) concentrically surrounding the screens. The exact configuration of the screen jacket assembly


12


is not critical to the invention and may be varied by those skilled in the arts. The screen jacket assembly is generally constructed around a base pipe (not shown), which has a plurality of perforations through which fluids can communicate between the interior of the base pipe and the wellbore


16


.




Now referring primarily to

FIG. 1

, with the radially expandable sand-control screen jacket assembly


12


positioned in the desired location


14


of the wellbore


16


in the conventional manner, an annular space


20


exists between the outermost surface


13


of the unexpanded screen jacket


12




a


and the wall


18


of the wellbore


16


. The expansion assembly


10


is positioned concentrically within the radially expandable sand-control screen jacket assembly


12


. The expansion assembly


10


is preferably connected to the terminal end of a conventional pipe string


22


. The pipe string


22


is a fluid communication with a fluid pump as shown), used to supply fluid to the expansion assembly


10


. The expansion assembly


10


has a washing assembly


24


preferably at its upper end. The washing assembly


24


has a housing


26


with a main passage


28


to allow fluid communication longitudinally throughout its length. Preferably, a washing port


30


is located in the side of the washing assembly housing


26


in fluid communication with the main passage


28


. The washing port


30


is sized to divert a portion of the fluid flow from the main port


28


to the exterior of the washing assembly housing


26


. Optionally, a plurality of washing ports may be used. A seal element


32


is affixed adjacent the forward end


34


of the washing assembly


10


. The seal element


32


is preferably made from elastomeric material and is in substantially fluid-sealing contact with the inner surface


36


of the unexpanded screen jacket assembly


12




a


.




Still referring primarily to

FIG. 1

, a swedge portion


38


of the expansion assembly


10


is connected to the lower end


40


of the washing assembly housing


26


. The main passage


28


continues through the center of the swedge portion


38


of expansion assembly


10


. The swedge portion


38


is in the general shape of a truncated cone or circular wedge. The outer surface


42


of the swedge


38


is preferably defined by a plurity of segments


46


. The segments


46


are moveable by means of fluid pressure communicated from the main passage


28


in a manner known in the arts, having a radially expanded position (not shown) and a radially retracted position as shown in FIG.


1


. The swedge segments


46


preferably have grooves along at least a portion of their surfaces. Optionally, the swedge


38


may be non-expandable or smooth-surfaced. As shown in the art, if a non-expandable swedge is used (not shown), it must be placed adjacent to an end of the unexpanded screen jacket assembly for movement into the screen jacket assembly during the step of expanding the screen jacket assembly.




Further referring primarily to

FIG. 1

, the lower end


50


of the swedge


38


is preferably connected to a force generator


52


. The main passage


28


continues through the force generator


52


, which is preferably hydraulically operated The force generator


52


is capable of forceful longitudinal movement between an extended position (not shown) and a home position, depicted in FIG.


1


. The preferred downhole force generator


52


has a nippleless lock for selectable radial locking in contact with the inner surface


36


of the screen jacket assembly


12


. The nippleless lock has a radially locking position (not shown) and a radially contracted position, shown in FIG.


1


. Optionally, other downhole force generators may be used to longitudinally drive the expansion swedge with sufficient force to expand the screen jacket assembly as are known in the art. For example, a system such as that disclosed in U.S. Pat. No. 5,492,173, which is assigned to this assignee and is incorporated herein for all purposes by this reference, can be used. The downhole force generator is preferably self-contained, or may be in communication to the surface via slickline, power connections, or control connections. The exact configuration of the force generator and lock are not crucial to the invention so long as selectable directed force is provided to the swedge


38


.




Referring now primarily to

FIG. 2

, the expansion assembly


10


is shown in the expanded position with the radially expandable sand-control screen jacket


12


partially enlarged by the swedge


38


. The swedge


38


is forced, upward as shown here, by force generator


52


, thereby expanding the screen assembly


12


from its run-in position


12




a


to its expanded position


12




b


. Washing fluid


56


is pumped through the pipe string


22


into the main passage


28


. The flow path of the washing fluid


56


is shown by the arrows in FIG.


2


. In particular, the washing fluid


56


flows into the main passage


28


at the forward end


34


of the washing assembly housing


26


. A portion of the washing fluid


56


flows through wash port


30


. The washing fluid


56


flowing through wash port


30


flows through the unexpanded portion of the screen jacket assembly


12




a


and into the annular space


20


between the outer surface


13


of the unexpanded screen jacket assembly


12




a


and the wellbore wall


18


. The flow of washing fluid


56


from the wash port


30


into the annular space


20


surrounded by the seal element


32


and by the swedge outer surface


42


proximal to the lower end


40


of the washing assembly housing


26


. The fluid flow in the annular space


20


is preferably turbulent but may optionally be laminar. The fluid flow in the annular space


20


washes debris from the screen surface and from the annular space


20


and scours the wall


18


of the wellbore


16


reducing skin factor. Preferably, the washing fluid


56


also flows through grooves in the swedge


38


, washing the screen


12


and annular space


20


where the swedge outer surface


42


contacts the inner surface


36


of the screen jacket assembly


12


.




The composition of the washing fluid


56


may be varied according to well and formation conditions. For example, fluid


56


may be water or an acid solution. Further referring primarily to

FIG. 2

, the washing fluid


56


may be used to hydraulically operate the swedge


38


. As the washing fluid


56


flows through passage


28


, the swedge expands radially. The radial expansion of the swedge surface


42


in turn causes the screen jacket assembly


12




b


to radially expand into the annular space


20


between the outer surface


13


of the screen jacket assembly


12


and the wall


18


of the wellbore


16


. Optionally, the swedge


38


may be operated via a separate hydraulic, mechanical or electrical actuator.




The washing fluid


56


may further be employed to actuate the force generator


52


. The flow of the washing fluid


56


also causes the preferred force generator


52


to move from a home position (not shown) to an extended position as shown in

FIG. 2

, driving the swedge


38


and washing assembly


24


upward through the screen jacket assembly


12


. The force generator


52


may include other elements such as a radially expanding lock, not shown, as is know in the art. As the washing assembly


24


and swedge


38


are advanced through the screen jacket assembly


12


, the screen jacket assembly


12




a


is radially expanded,


12




b


. When the force generator


52


becomes fully extended, it is moved up hole into a home position, thereby “inch worming” the assembly along the well bore, as is known in the art. The swedge


38


may act as an anchor when advancing the force generator. The washing and expanding process described above may be repeated. The operation rate repeated until the desired length of screen jacket assembly has been expanded.




In an alternative embodiment of the invention depicted in

FIG. 3

, the expansion assembly


10


and methods may be used for radially expanding a sand-control screen jacket assembly


12


in a subterranean well from top-to-bottom, that is, in the downhole direction.




Washing fluid


56


is pumped downhole into main passage


28


. As with the bottom-up method previously discussed, fluid


56


may be used to drive the swedge


38


along the length of the screen assembly


12


, thereby expanding it from its run-in position


12




a


to its expanded position


12




b


. At least a portion of washing fluid


56


flows out of the passage


28


through wash port


30


.




Optionally, the washing assembly is provided with a trash tube


58


having a passage


28




a


through which fluid


56


flows. The washing assembly may also have a flow control orifice


60


sized to regulate the flow rate once the fluid


56


is at expansion pressure.




Upon exiting the housing


26


via port


30


, the fluid


56


flows downhole along the annular space


62


between the return pipe


64


and the inner surface


36


of the screen


12


. Fluid


56


is prevented from flowing uphole by flow control seal


66


. Port


30


is located downhole from flow control seal


66


. Fluid


56


may flow into annular space


62


along grooves provided on the exterior of swedge


36


for that purpose.




Flow control seal


68


, which blocks the annular space


62


downhole of swedge


38


, forces the fluid


56


to flow outward from annular space


62


through the screen assembly


12


and into the annular space


20


formed between the unexpanded screen


12




a


and the wall


18


of the borehole


16


.




The washing fluid


56


, pushed outward through the screen assembly


12


by the advancing expansion swedge


38


washes any build-up from the outer surface


13


of the screen assembly


12


. Fluid


56


flows downhole through annular space


20


and washes the borehole


16


, thereby reducing the skin factor of the borehole and washing cuttings, loose filter and other debris from the borehole.




Downhole from flow control seal


68


, is located a similar flow control seal


70


. A portion of fluid


56


may flow back through the screen assembly


12


, below seal


68


, from annular space


20


to annular space


62


. Washing fluid


56


, or a portion thereof, may also continue to flow downhole along annular space


62


, carrying mud, suspended materials, cuttings and loose filter cake with it.




Optional return ports


72


are provided in the preferred embodiment. Portions of fluid


56


, carrying debris, may return to annular space


62


through return ports


72


.




Washing fluid


56


flows through wash port


74


into passage


28




b


in return pipe


64


. Washing fluid


56


returning to the surface, uphole, passes along passage


28




b


, through wash port


76


, which may optionally be capable of opening and closing, and upward along annular space


62


above flow control seal


66


.




Circulation ports


72


may optionally be closeable, allowing the ports to be sealed after expansion of the screen assembly


12


such that production fluids must flow through the screen assembly


12


rather than through the ports


72


. One preferred method of closing ports


72


is shown in

FIG. 4

although other methods are known in the arts. Port closure plate


80


is located adjacent the ports


72


on the outer surface


13


of the screen assembly at attachment


82


as shown. When the screen assembly


12


is in its run-in, or un-expanded state


12




a


, the closure plate does not prevent flow of fluid


56


through ports


72


. As swedge


38


expands screen assembly


12


, he closure plate


80


is bent and flattened against the outer surface


13


of the screen assembly


12


thereby covering ports


72


and preventing further fluid flow through the ports


72


, as seen at


80




a


in FIG.


3


. Optionally, rubber seals


84


are provided.




Optionally, return pipe


64


, at its downhole end, may be provided with a float shoe assembly


86


. Fluid


56


, flowing into annular space


62


downhole from flow control seal


70


, may flow through check valve


88


. Check valve


88


acts as a relief valve, allowing fluid from downhole to flow into the return pipe


64


when a selected downhole pressure is achieved.




It will be clear to those skilled in the arts that the apparatus and methods disclosed may be used for top-down or bottom-up screen expansion and borehole washing. The inventions have several advantages over the apparatus and methods previously known in the art, including the advantages of pressure washing the annular space between the outer surface of the screen jacket assembly and the wall of the wellbore. The self-contained expansion tool also provides advantages including the elimination of surface connections. The radially expandable swedge of the preferred embodiment also has the advantage of being deployable in its unexpanded position through an unexpanded screen jacket assembly.




The embodiments shown and described above are only exemplary. Many details are often found in the art such as: force generator, screen jacket, or expansion swedge configurations and materials. Therefore, many such details are neither shown nor described. It is not claimed that all of the details, parts, elements, or steps described and shown were invented herein. Even though numerous characteristics and advantages of the present inventions have been set forth in the foregoing description, together with details of the structure and function of the inventions, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size and arrangement of the parts within the principles of the inventions to the full extent indicated by the broad general meaning of the terms used in the attached claims.




The restrictive description and drawings of the specific examples above do not point out what an infringement of this patent would be, but are to provide at least one explanation of how to make and use the inventions. The limits of the inventions and the bounds of the patent protection are measured by and defined in the following claims.



Claims
  • 1. An apparatus for washing a subterranean borehole and radially expanding a screen assembly comprising:a washing assembly for washing the borehole; and an expansion assembly for radially expanding the screen assembly.
  • 2. An apparatus as in claim 1 wherein the washing assembly further comprises:a washing assembly housing having a housing wall, the housing wall defining an interior passage therein; a wash port through the housing wall for providing fluid communication between the interior passage of the washing assembly and the borehole annular space; and a flow control element affixed to the washing assembly housing for substantially preventing fluid flow along a screen annular space, the screen annular space defined by the inner surface of the screen assembly and the wall of the housing assembly.
  • 3. An apparatus as in claim 1 further comprising a force generator for operating the expansion assembly.
  • 4. An apparatus as in claim 1 wherein the force generator is hydraulically operable by washing fluid pumped into the subterranean well.
  • 5. An apparatus as in claim 1 wherein the expansion assembly includes a radially expandable swedge.
  • 6. An apparatus as in claim 1 wherein the expansion assembly operates in the downhole direction.
  • 7. An apparatus as in claim 6 further comprising a return flow passage providing fluid communication between an area of the borehole downhole from the expansion assembly to an area of the borehole uphole from the expansion assembly.
  • 8. An apparatus as in claim 7 wherein the return flow passage includes at least one closeable return port.
  • 9. An apparatus as in claim 7 wherein the return flow passage further includes a relief valve.
  • 10. An apparatus as in claim 1 further comprising a radially expandable screen assembly.
  • 11. A method of working a subterranean well having a borehole, the method comprising the steps of:running in a downhole tool assembly having a washing assembly and an expansion assembly for radially expanding a sand screen assembly; expanding the sand screen assembly in the borehole; and flowing washing fluid through at least a portion of the borehole.
  • 12. A method as in claim 11 wherein the steps of expanding the sand screen and flowing washing fluid are done simultaneously.
  • 13. A method as in claim 11 further comprising the step of running in a downhole tool assembly having a radially expandable screen assembly, a washing assembly adjacent the screen assembly, and an expansion assembly for radially expanding the screen assembly.
  • 14. A method as in claim 13 wherein the washing assembly includes a housing having a housing wall, the housing wall defining an interior passage therein;a wash port through the housing wall for providing fluid communication between the interior passage of the washing assembly and the borehole annular space; and a flow control element affixed to the washing assembly housing for substantially preventing fluid flow along a screen annular space, the screen annular space defined by the inner surface of the screen assembly and the wall of the housing assembly.
  • 15. A method as in claim 14 wherein the step of flowing washing fluid through a portion of the borehole annular space further includes the steps of flowing washing fluid through the interior passage of the washing assembly housing, flowing washing fluid through the wash port of the washing assembly into the borehole annular space.
  • 16. A method as in claim 15 wherein the step of flowing washing fluid through a portion of the borehole annular space further includes the step of flowing washing fluid from an interior passage of the screen assembly outward to the borehole annular space.
  • 17. A method as claim 14, the washing assembly having a return passage for returning the washing fluid to the well surface, the method further comprising the step of flowing the washing fluid uphole to the surface of the well through the return passage, after the step of flowing washing fluid through a portion of the borehole annular space.
  • 18. A method as in claim 17 wherein the step of flowing the washing fluid uphole further includes flowing the washing fluid uphole through the return passage in the washing assembly.
  • 19. A method as in claim 11 further comprising the steps of:running into the borehole an expandable screen assembly; and running into the borehole a washing assembly.
  • 20. A method as in claim 11 wherein the step of expanding a screen assembly further comprises expanding a radially expandable swedge and running the expanded swedge through at least a portion of the screen assembly, thereby expanding the screen assembly.
  • 21. A method as in claim 20 wherein the expanded swedge is run by the force of the washing fluid.
  • 22. A method as in claim 11 wherein the step of flowing washing fluid through the borehole annular space further comprises flowing washing fluid from uphole of the portion of the borehole to be washed.
  • 23. A method as in claim 11 wherein the screen assembly is expanded from the top downward.
  • 24. A method as in claim 11 further comprising the step of flowing the washing fluid uphole to the surface of the well, after the step of flowing washing fluid through a portion of the borehole annular space.
  • 25. A method as in claim 11 further comprising the step of running in a radially expandable screen assembly.
  • 26. A method as in claim 11 wherein the sand screen assembly is expanded weight down.
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