GB2539998A - Wellbore filtration tool with novel wiper cup - Google Patents

Abstract

A wellbore cleaning tool and method featuring a wiper assembly 26 which allows fluid to bypass the tool in one direction while diverting the well fluid through a filter screen in another direction. The apparatus is formed of a tool body with an inner bore, a debris chamber 35, a wiper assembly and a screen. The wiper assembly includes multiple groups or series of circumferentially spaced wiper elements 39, the wiper elements having gaps or slots 43 located between them. Wherein one petal shaped element of one group of wiper elements is aligned longitudinally with a slot or gap in a second group of circumferentially spaced wiper elements to form a seal when the tool body is retrieved from the well. This may be achieved by either circulation of the fluid in the wellbore or by moving the tool relative to the fluid in the wellbore. A separate independent claim discloses an embodiment wherein the wiper elements may move between retracted and extended positions.

Description

WELLBORE FILTRATION TOOL WITH NOVEL WIPER CUP

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to the removal of debris from oil and gas wells. More particularly, the present invention relates to an improved method and apparatus for removing debris from an oil and gas well tubular or tube shaped member or pipe (e.g., casing) wherein the apparatus employs specially configured petals and slots that enable flow outside the tool body in both up and down directions. 2. General Background of the Invention [0002] In general, the removal of debris from oil and gas wells is well documented. There are many examples of prior art which include scrapers and brushes to mechanically clean the interior surface of casing of the well. Likewise, there are examples of tools designed to remove the debris from the wellbore after it has been scraped and/or brushed. This is an important function of a wellbore clean-up operation as the removal of junk and debris help mitigate against failure of downhole equipment, particularly when circulation of wellbore fluid alone is insufficient to ensure hole cleaning. Magnets are often used for this purpose, however not all wellbore debris is ferrous. Therefore, some debris must be removed by a mechanical means.

[0003] Some prior art devices (e.g., see U.S. Patent 6,250,387) use a wiper cup made of a flexible but high strength rubber, typically supported by metal wires which are moulded into the rubber. The rubber and wire work together to provide sealing and wiping capability as well as resistance to tearing. One problem with this type of device is that the wiper cup is adapted from use as a one directional seal whereby fluid pressure on the inside of the cup bellows the cup outwards to create a seal.

[0004] Fluid pressure on the outside of the cup causes it to partially collapse, allowing pressure to bypass the cup. The wiper cup can hold pressure in only one direction. It cannot allow significant volumes of fluid or debris laden fluid to flow past it in the opposite direction, particularly the volumes required to perform an effective wellbore clean-up. This is due to the shape of the cup which form a continuous seal on the inside of the wellbore, as well as the materials used which while being rubberized are still relatively stiff and resilient in order to be robust enough to work in a downhole environment.

[0005] In order to allow the high volume of debris laden fluid to pass the tool, the device of US 6,250,387 discloses a series of check valves. This allows fluid to pass through the tool in one direction bypassing the filter, and works in conjunction with the wiper cup to divert fluid through the screen in another direction. The check valves which act as a diversion means for the filtered fluid often become blocked by larger debris and junk resulting in the wellbore fluid partially or completely bypassing the filter and therefore rendering the tool useless. The wire wrapped screen used on this device is prone to damage whereby junk becomes trapped in the annular volume between the screen and the casing. Due to rotation of the tool, the wire screen can become damaged and fail catastrophically.

[0006] The largest external components are used for stand-off and are attached such that they rotate with the tool. It is commonly accepted that wellbore clean-up tools which feature non-rotating centralizers (centralizers which can remain stationary while the tool rotates) prevent casing and tool wear. The ‘burst disks’ used on the US 6,250,387 as an emergency bypass are prone to opening accidentally which allows partial or complete bypass of the filter, which occurs most often when the drilling rig ‘pumps a slug’ (a method of lowering the fluid level in the wellbore by placing an artificially high density pill into the work-string which over-pressures the burst disk).

SUMMARY

[0007] In one embodiment, the present invention provides an improved wellbore (e.g., tubular casing) cleaning and filtration tool. The present invention addresses the issues of wiping the casing and filtering the wellbore fluid of debris while being removed from the well.

[0008] The apparatus of the present invention is structurally comprised of a top “sub” (i.e., short length of pipe or tubular) and a mandrel which are mated together via an internal connection (e.g., threaded) to form a tool body. The tool body provides an open ended axial bore running throughout its length. An upper connection is provided on the top “sub” and a lower connection on the bottom of the mandrel. The upper and lower connections are employed to connect the tool body to a conventional drill string. A wiper assembly on the tool body separates an upper annulus from a lower annulus. The tool body includes a debris chamber as defined by a perforated filter screen and filter shroud located on the mandrel. The tool body also features a centralizer ring to prevent damage to the apparatus while downhole. This ring can be the largest non-flexible outer diameter (O.D.) surface of the tool body.

[0009] During use, the apparatus is connected to the drill string and lowered into the wellbore. The wiper assembly is slightly larger than the internal diameter of the wellbore (i.e., casing) so as to cause an interference between to wipe the internal wall of the wellbore while the tool body is lowered into the well.

[0010] The wiper assembly consists of a series of overlapping wiper elements. Each wiper component can be a petal or petal shaped member. The wiper elements include a non-flexible backing ring made of steel or other metal to which is bonded a flexible wiper petal ring made of a flexible wiper compounds (e.g., rubber, polymer) such that the two pieces form a composite part. The external surfaces of the ring and wiper petal ring can be tapered so as to bias the wiper petal ring to deform in one direction while preventing it from deforming in another direction.

[0011] There are a series of circumferentially spaced apart slots which extend longitudinally through the backing ring and wiper petal ring. The petals and slots are so positioned that when the wiper elements are stacked together all the petals of a lower wiper element can deform and form a reasonably tight fit with the slot of the wiper element immediately above it. The petals are circumferentially spaced apart. As an example, there can be ten (10) petals spaced thirty-six degrees apart for a first wiper ring or group. The next, adjacent wiper ring or group could also have ten (10) petals spaced thirty six (36) degrees apart. However, the petals of the first group are spaced circumferentially eighteen degrees from the petals of the second group. In this fashion, gaps between petals of the first group align with petals of the second group. A third group of petals aligns with the gaps of the second group.

[0012] Each wiper element can be stacked on and bonded to a wiper inner sleeve and arranged so that each group or series of petals and slots form an interlocking pattern whereby when fluid passes in one direction the petals can retract fully inside the slots of the wiper element immediately above it, and also that when fluid flows in an opposite direction that the interlocking petals form a rudimentary seal which largely prevent fluid from passing in the opposite direction. While this invention discloses a composite part consisting of multiple stacked elements, it is also possible to manufacture the wiper assembly by using a single moulding.

[0013] Whilst the tool is lowered into the wellbore, debris laden fluid passes from the lower annulus to the upper annulus and outside the perforated filter screen and past the outside of the wiper assembly which deforms to a collapsed position in the manner described. An axial bore allows for pumping of chemicals and fluids to assist in cleaning the well.

[0014] When the tool body is removed from the wellbore, the wiper assembly wipes the internal wall of the wellbore. The petals prevent debris from passing around the wiper assembly and diverts debris laden fluid from the upper annulus through fluid entry ports/courses and into the debris chamber.

[0015] A perforated filter screen traps the debris in the debris chamber while at the same time allowing filtered/clean fluid to pass through the perforated filter screen and the filter shroud to the outside of the tool body and exit into the lower annulus.

[0016] In the event that the debris chamber fills completely, a pressure differential is created between the debris chamber and the lower annulus which causes the bypass valve to open enabling fluid to drain from the upper annulus to the lower annulus, bypassing the perforated filter screen.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0017] For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:

Figure 1 is a longitudinal, sectional view of a preferred embodiment of the present invention.

Figure 2 is longitudinal, sectional view of the embodiment shown in Figure 1 being lowered, and showing the wiper assembly in a retracted condition.

Figure 3 is an enlarged sectional view of Figure 2 schematically illustrating flow around the embodiment of Figure 1 during lowering, and showing the wiper assembly in a retracted condition.

Figure 4 is longitudinal, sectional view of the embodiment shown in Figure 1 being raised, and showing the wiper assembly in an extended condition.

Figure 5 is an enlarged sectional view of Figure 4 schematically illustrating flow through the filtering system of the embodiment of Figure 1 during raising, and showing the wiper assembly in an extended condition.

Figure 6 is a sectional view taking through lines 6 -- 6 of Figure 3.

Figure 7 is a sectional view taking through lines 7 -- 7 of Figure 6.

Figure 8 is an enlarged perspective view of the embodiment of Figure 2 schematically illustrating flow around the embodiment of Figure 1 during lowering, and showing the wiper assembly in a retracted condition.

Figure 9 is an exploded perspective view of the embodiment of Figure 2 schematically illustrating the condition for flow during lowering, and showing the wiper assembly in a retracted condition, and showing the plurality of wiper rings and wiper elements making up the wiper assembly.

Figure 10 is a sectional view taking through lines 10 --10 of Figure 5.

Figure 11 is a sectional view taking through lines 11 --11 of Figure 10.

Figure 12 is an enlarged perspective view of the embodiment of Figure 4 schematically illustrating flow through the filtering system during raising, and showing the wiper assembly in an extended position.

Figure 13 is an exploded perspective view of the embodiment of Figure 4 schematically illustrating flow through the filtering system during raising, and showing the wiper assembly in an extended condition, and showing the plurality of wiper rings and wiper elements making up the wiper assembly.

DETAILED DESCRIPTION

[0018] The apparatus of the present invention is designated generally by the numeral 5. Apparatus 5 provides an elongated tool comprised of a top sub 11 and of a mandrel 12 which are mated together via an internal connection 31. Top “sub” 11 is simply a short length of pipe or tubular materials. Such “subs” are known and commercially available. The tool body 6 features an open ended axial bore 32 running through out its length. Tool body 6 has an upper connection 30 on the top sub 11 and a lower connection 37 on the mandrel 12.

[0019] The upper and lower connections 30 and 37 are employed to connect the tool body 6 to a conventional drill string. Wiper assembly 26 separates upper annulus 33 from the lower annulus 36. The tool body 6 includes a debris chamber 35 having perforated filter screen 19 and filter shroud 20 located over the mandrel 12. The tool body 6 also features non-rotating, contact, centralizer ring 15 to prevent damage to the tool while downhole. This is the largest non-flexible OD (outer diameter) surface of the tool body 6. In order to clean bore 10, the tool body 6 is connected to a drill string and lowered into the wellbore 10.

[0020] An Ο-ring 13 can be placed at the connection 31. Centralizer bearing ring 15 is mounted to the outside of tool body 6 in between wiper assembly 26 and debris chamber 35. Bearing ring 14 is mounted to tool body 6 in between debris chamber 35 and lower connection 37. Tool body 6 includes split ring 16, conical spring 17 and back out bolt 18.

[0021] In one embodiment apparatus 5 can include wiper assembly 26. The identifiers and are used to indicate items of substantially the same construction, but of a different piece.

[0022] In one embodiment, the wiper assembly 26 consists of a series or groups of wiper groups 28, 28’, 28”, 28”’, and 28””. In one embodiment each wiper group 28 can include a flexible wiper petal ring 39 and a relatively non-flexible backup ring 38. In one embodiment flexible petal ring 39 can have a plurality of circumferentially spaced apart wiper elements.

[0023] The flexible petal rings 39, 39’, 39”, 39’”, and 39”” can be mounted next to relatively non-flexible backing rings 38, 38', 38”, 38’”, and 38”” which can be made of steel or other metal. The flexible petal rings 39, 39', 39”, 39’”, and 39”” can be made of rubber or other flexible compounds. The non-flexible backing rings 38, 38', 38”, 38’”, and 38”” can be respectively bonded to the flexible petal rings 39, 39’, 39”, 39’”, and 39”” such that each of the respective set of two pieces form a composite part.

[0024] The external surfaces of the backing rings 38 and wiper petal rings 39 can be tapered so as to bias each wiper petal ring 39 to deform in one direction while preventing it from deforming in another direction.

[0025] Each petal ring 39 can have a plurality of circumferentially spaced apart wiper elements (e.g., petal rings 39, 39’, 39”, 39’”, and 39”” respectively each having plurality of wiper elements 45, 46, 47, 48) which wiper elements can be in the shape of a petal 44. There can be spaces or slots 43 between each pair of wiper elements (see figures 8-9 and 12-13).

[0026] There can be a series of slots 43 which extend longitudinally through the plurality of backing rings 38, 38', 38”, 38’”, and 38”” and wiper petal rings 39, 39’, 39”, 39’”, and 39”” which are patterned circumferentially. Each petal ring 39 thus includes alternating petals 44 and slots 43. The width of the slots 43 are only slightly larger than the width of the petal 44 such that when the wiper elements 45, 46, 47, and 48 are stacked together all the petals 44 of a lower wiper ring can deform and form a reasonably tight fit with the slot 43 of the wiper ring immediately above it.

[0027] Each wiper element (e.g., sets of wiper elements 45, 46, 47,48) can be stacked on and bonded to a wiper inner sleeve 40 and arranged so that each group or series of petals 44 and slots 43 form an interlocking pattern whereby when fluid passes in one direction the wiper elements 45, 46, 47, and 48 can retract fully inside the slots 43 of the wiper element immediately above it (respectively wiper elements 45 into 46, 46 into 47, and 47 into 48 - - see figures 7-9). When fluid flows in an opposite direction (e.g., schematically shown be arrows 21) the interlocking petals 44 form a rudimentary seal which largely prevents fluid from passing in the opposite direction (see figures 4, 5, and 11-13).

[0028] Each backup ring 38 can have a plurality of circumferentially spaced apart backup prongs 60 which can be located immediately below one of the respective wiper elements to provide backup up support to the respective wiper element when the apparatus 5 is being pulled up (schematically indicated by arrow 110). Additionally the spaced apart backup prongs 60 can be spaced such that wiper elements of a lower backup ring can fit between the gaps in the backup prongs 60 of the next located upper backup ring (see Figure 8).

[0029] While the present invention discloses a composite part consisting of multiple stacked wiper groups 28, 28', 28”, 28”’, 28””, it is also possible to manufacture the wiper assembly 26 by using a single moulding.

[0030] As schematically shown in Figure 2 and 3, while tool body 6 is lowered into the wellbore 10 (schematically indicated by arrow 100), debris laden fluid passes from lower annulus 36 to upper annulus 33 outside the perforated filter screen 19 and past the outside of wiper assembly 26 (see arrows 13, figures 3, 7, and 8) which deforms in the manner described to a collapsed position. Arrows 102 in Figure 7 schematically indicate that, as apparatus 5 is lowered in the direction of arrow 100, the wiper elements of wiper assembly 26 are placed in a retracted state by fluid flow relative to wiper assembly in direction of arrow 13.

[0031] In one embodiment, the wiper assembly 26 can be slightly larger than the internal wall of the wellbore 10 so as to cause an interference between the two, and wipe the internal wall 9 of the wellbore 10 while the apparatus 5 is lowered into the wellbore 10.

[0032] As schematically shown in Figures 4 and 5, when the tool body 6 is removed from the wellbore 10 (schematically indicated by arrow 110), the wiper assembly 26 wipes the internal surface or internal wall 9 of the wellbore 10. The wiper elements 45, 46, 47, and 48 prevent debris from passing around the wiper assembly 26 and diverts debris laden fluid from the upper annulus 33 through the fluid entry ports/courses 34 (see arrows 21, figure 5) and into the debris chamber 35 (see arrows 21, figure 5) which collects the filtered out debris 50. Arrows 112 in Figure 11 schematically indicate that, as apparatus 5 is raised in the direction of arrow 110, the wiper elements of wiper assembly 26 are placed in an extended state by fluid flow relative to wiper assembly in direction of arrow 21.

[0033] The perforated filter screen 19 traps the debris 50 in chamber 35 while at the same time allowing filtered/clean fluid to pass through the perforated filter screen 19 and the filter shroud 10 and exit into the lower annulus 36.

[0034] In one embodiment, axial through bore 32 allows for pumping of chemicals and fluids to assist in cleaning the well during the process of lowering (arrow 100) and/or raising (arrow 110) apparatus 5.

[0035] In one embodiment can be included a bypass valve 13 for the debris chamber 35. In the event that the debris chamber 35 fills completely, a pressure differential is created between the debris chamber 35 and the lower annulus 26 which causes the bypass valve 13 to open and the fluid to drain from the upper annulus 33 to the lower annulus 26, bypassing the perforated filter screen 19.

[0036] The following is a list of parts and materials suitable for use in the present invention:

PARTS LIST

PART NUMBER DESCRIPTION 5 apparatus 6 tool body 8 casing 9 inside surface/internal wall 10 wellbore 11 top sub 12 mandrel 13 arrow 14 arrow 15 centralizer ring 19 perforated filter screen 20 filter shroud 21 arrows 23 bypass valve 26 wiper assembly 28 wiper group 30 upper connection 31 internal connection 32 axial bore 33 upper annulus 34 fluid entry ports 35 debris chamber 36 lower annulus 37 lower connection 38 wiper backing ring 39 wiper petal ring 40 wiper inner sleeve 41 petal bonding location 42 fluid path 43 slots 44 petal 45 wiper element 46 wiper element 47 locking pin 50 collected debris 100 arrow 102 arrow 110 arrow 112 arrow [0037] All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise.

[0038] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0039] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0040] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0041] The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.

Claims (18)

CLAIMS:

1. Apparatus for removing debris from a well bore, comprising: a) a tool body having an outside surface, upper and lower end portions with connectors that enable connection of the tool body to a work string; b) the tool body having an inner bore that enables fluid flow through the tool body and between said upper and lower end portions; c) a debris chamber; d) a wiper assembly mounted to the tool body in between said upper end and lower end portions; e) a channel that is in between the tool body outer surface and the tool body bore, said channel enabling fluid to flow from a position above the wiper assembly to said debris chamber; f) a screen that enables fluid to exit the debris chamber wherein the screen retains debris; g) wherein the wiper assembly includes a first plurality of circumferentially spaced apart petals and a first plurality of circumferentially spaced apart slots, each slot of the first plurality between two of said petals of the first plurality; h) wherein the wiper assembly includes a second plurality of circumferentially spaced apart petals and a second plurality of circumferentially spaced apart slots, each slot of the second plurality placed in between two of said petals of the second plurality; and i) wherein petals of the first plurality are aligned longitudinally with slots of the second plurality so that when fluid flows on the outside of the tool body in a direction from the upper end portion to the lower end portion, the petals of the first plurality cover the slots of the second plurality to retard fluid flow past the wiper assembly.

2. The apparatus of claim 1, wherein each petal is of a rubber material.

3. The apparatus of claim 1 or 2, wherein the petals are mounted to an inner sleeve that is on the outside surface of the tool body.

4. The apparatus of any preceding claim, further comprising a third plurality of petals and a third plurality of slots.

5. The apparatus of any preceding claim, wherein the petals collapse toward the tool body enabling fluid flow along the outside surface of the tool body in a direction from the lower end portion to the upper end portion.

6. The apparatus of any preceding claim, wherein the petals of the first plurality are of a similar shape.

7. The apparatus of claim 6, wherein petals of the first plurality have a shape that differs from the shape of the petals of the second plurality.

8. The apparatus of any preceding claim, wherein the slots define a flow path for fluid that is not a linear path.

9. The apparatus of any preceding claim, wherein the slots of the first plurality are in fluid communication with the slots of the second plurality when fluid flows from the lower end portion to the upper end portion.

10. The apparatus of any preceding claim, wherein fluid flowing from the lower end portion to the upper end portion does not enter the channel.

11. A method of cleaning a wellbore tubular comprising the steps of: a) lowering a tool body on a pipe string into a well; b) wiping the tubular with the tool body; c) wherein the wiper is configured to enable fluid to flow pass the wiper in either direction and externally of the tool body; and d) wherein in step “c” the wiper includes petals that move between retracted and extended positions. e) collecting the debris in a debris chamber on the tool body;

12. The method of claim 11, further comprising separating fluid and debris at the debris chamber.

13. The method of claim 11 or 12, wherein in step “d” there are a first plurality of petals and a second plurality of petals and a gap between each pair of petals and further comprising aligning each petal of the first plurality with a gap between two petals of the second plurality.

14. The method of claim 13, wherein the petals of the first plurality are spaced circumferentially apart equal distances.

15. The method of claim 14, wherein petals of the second plurality are spaced circumferentially apart equal distances.

16. A method of cleaning a wellbore tubular comprising the steps of: a) lowering a tool body on a pipe string into a well; b) wiping the tubular with the tool body; c) wherein the wiper is configured to enable fluid to flow pass the wiper in either direction and externally of the tool body, the wiper being moved between retracted and expanded positions; d) wherein in step “c” the wiper includes a first plurality of circumferentially spaced apart wiper elements and a gap in between each pair of said wiper elements of the first plurality and a second plurality of wiper elements that are spaced longitudinally from said first plurality, wherein said wiper elements move between expanded and retracted positions; e) closing a said gap with a wiper element of the second plurality in the expanded position; and f) collecting the debris in a debris chamber on the tool body.

17. Apparatus for removing debris from a well bore, substantially as hereinbefore described with reference to or as shown in the accompanying drawings.

18. A method of cleaning a wellbore tubular, substantially as hereinbefore described with reference to or as shown in the accompanying drawings.