EP2843183A1

EP2843183A1 - Downhole annular base structure

Info

Publication number: EP2843183A1
Application number: EP13182407.0A
Authority: EP
Inventors: Lars Staehr; Ricardo Reves Vasques; Hans Plessing
Original assignee: Welltec AS
Current assignee: Welltec AS
Priority date: 2013-08-30
Filing date: 2013-08-30
Publication date: 2015-03-04

Abstract

The present invention relates to a downhole annular base structure for being set downhole in an open hole part of a well by means of a downhole setting tool having a tool body, the annular base structure having a longitudinal extension, comprising a first end part having an indentation in an inner face, in which indentation a sealing means is arranged so that the first end part is slidable in relation to the tool body along the longitudinal extension, a second end part having an indentation in an inner face, an expandable centre part having a wall thickness which is smaller than those of the first and second end parts, wherein the second end part comprises a release element engaging the indentation for maintaining the second end part to the tool body along the longitudinal extension during positioning and/or expansion. The present invention also relates to a downhole setting tool, to a downhole sealing system and to a setting method for setting an annular base structure according to the invention.

Description

Field of the invention

The present invention relates to a downhole annular base structure for being set downhole in an open hole part of a well by means of a downhole setting tool The present invention also relates to such downhole setting tool, to a downhole sealing system and to a setting method for setting an annular base structure according to the invention.

Background art

A well sometimes has a cased part and an un-cased part, the un-cased part also being referred to as an open hole well. Most often the production zone in which the hydrocarbon-containing fluid flows out of the reservoir is arranged in the open hole part of the well. Eventually, the production zone will produce too much water, such as in the case of a water breakthrough, and there is thus a need to shut off the production zone in the open hole part of the well. Since the open hole part has a diameter which is larger than that of the cased part, it may be difficult to set an annular sealing structure to isolate the production zone.

Summary of the invention

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved downhole sealing element and sealing system, rendering it possible to seal off an open hole production zone through a cased well part.
The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a downhole annular base structure for being set downhole in an open hole part of a well by means of a downhole setting tool having a tool body, the annular base structure having a longitudinal extension, comprising

a first end part having an indentation in an inner face, in which indentation a sealing means is arranged so that the first end part is slidable in relation to the tool body along the longitudinal extension,
a second end part having an indentation in an inner face, and
an expandable centre part having a wall thickness which is smaller than those of the first and second end parts,

The downhole annular base structure according to the present invention may further comprise an expandable element having a wall thickness which is larger than that of the centre part, the expandable element having a first end and second end and being adapted to be arranged on an outer face of the centre part.
The expandable element may be is made of a material which is more flexible than the material of the centre part.
Moreover, the centre part may be made of metal, such as steel.
Further, the first and second end parts may be made of metal, such as aluminium.
Also, the release element may project from the inner face of the second end part.
Additionally, the second end part may comprise sealing means.
Furthermore, the expandable element may comprise a plurality of annular elements arranged in succession of each other in the longitudinal extension.
Said annular elements may be made of different materials.
Moreover, the release element may comprise a charge for detonation.
Further, the release element may be a shear pin.
The centre part may be connected with the first and second end parts by means of welding, such as friction welding.
Also, the first end part may have a tapering extension.
The present invention also relates to a downhole setting tool for setting an annular base structure as described above in a well having a first well part with a casing string and a second well part without a casing string, the second well part having an inner diameter which is larger than that of the casing string, comprising

a tool body having a tool axis, a first end, a second end and an outer face, and
an annular base structure as described above, the first and second end parts abutting the outer face of the tool body and hence defining a space between the centre part and the tool body,

The tool body may comprise a fluid channel with an outlet in fluid communication with the space for expanding the annular base structure by means of pressurised fluid.
Moreover, the expandable element and the annular base structure may be arranged in succession along the tool axis.
Furthermore, the tool body may comprise a piston which is movable along the tool axis for pressing on the first end of the expandable element to arrange the expandable element on the outer face of the centre part.
Said piston may be arranged circumferenting the tool body.
Also, the tool body may comprise a groove extending along the tool axis on the outer face, and the piston may comprise a projecting element adapted for engaging the groove.
In addition, the piston may be arranged in the tool body.
Further, the tool body may comprise a second fluid channel in fluid communication with the piston.
Additionally, a second piston may be arranged in the fluid channel in the second end of the tool body opposite the second end part, the second piston having a cavity for reception of the release element when the second piston is in a second position, providing the cavity opposite the release element.
Moreover, the second piston may comprise two end discs having a first diameter, the two end piston parts being arranged with a mutual distance and being connected by an intermediate piston rod having a diameter which is smaller than the first diameter, creating the cavity.
The second piston may have an outer face and the cavity may be arranged in the outer face.
Furthermore, sealing means may be arranged between the second piston and the fluid channel.
Said sealing means may be arranged in an indentation in the fluid channel or in an indentation arranged in the second piston.
Also, a spring may be arranged upstream of the second piston for ensuring that the second piston is pressed into the second position.
Additionally, a shear disc may be arranged downstream of the second piston in the fluid channel.
Further, the expandable element may comprise friction enhancing elements of for instance embedded tungsten carbide, rock, stone, etc.
The downhole setting tool according to the present invention may further comprise an annular support arranged between the expandable element and the annular base structure.
The annular support may be made of a material which is less flexible than that of the expandable element.
Also, the annular support may be made of Polytetrafluoroethylene (PTFE).
The downhole setting tool as described above may further comprise a pump for pressurising fluid supplied through the fluid channel.
Moreover, the downhole setting tool as described above may further comprise a fluid chamber in fluid communication with the pump.
Furthermore, the fluid chamber may comprise a chamber piston dividing the chamber into a first chamber part and second chamber part, the first chamber part comprising fluid and being in fluid communication with the pump.
In addition, the second chamber part may comprise a spring.
Further, the second chamber part may be in fluid communication with well fluid.
Also, the second chamber part may comprise a gas, such as nitrogen, propane or the like.
The downhole setting tool as described above may further comprise a milling tool.
Additionally, the downhole setting tool as described above may further comprise an acid chamber.
Furthermore, the downhole setting tool as described above may comprise a driving unit.
The present invention also relates to a downhole sealing system for sealing off a zone in an open hole well, comprising

a first and a second annular base structure as described above set by the downhole setting tool as described above, the annular base structures being set and expanded with a mutual distance, and
a tubular element having a first and a second tubular end and being arranged between the two annular base structures, so that the first tubular end at least partly overlaps the first annular base structure, and the second tubular end at least partly overlaps the second annular base structure, the tubular element having an outer face,

wherein the tubular element is expanded so that the outer face abuts against an inner face of the annular base structures.
Further, the present invention relates to a downhole sealing system for sealing off a zone in an open hole well, comprising

a first and a second annular base structure as described above set by the downhole setting tool as described above, the annular base structures being set and expanded with a mutual distance,
a tubular element having a first and a second tubular end and being arranged between the two annular base structures, so that the first tubular end at least partly overlaps the first annular base structure, and the second tubular end at least partly overlaps the second annular base structure, the tubular element having an outer face, and
two packers arranged between the annular base structures and the tubular element.

Finally, the present invention relates to a setting method for setting an annular base structure as described above in a well having a first well part with a casing string and a second well part without a casing string, the second well part having an inner diameter which is larger than that of the casing string, said setting method comprising the steps of:

arranging the annular base structure on the tool body of the downhole setting tool as described above,
moving the setting tool through the casing string until the annular base structure is arranged in the second well part,
pressurising the fluid channel,
expanding the annular base structure,
releasing the tool body from the second end part, and
retracting the setting tool,

In said method, before the expansion step the expandable element may be arranged on the outer face of the centre part.
Also, the setting method described above may comprise the step of removing the end parts.
Said step of removing the end parts may be performed by milling or acid.

Brief description of the drawings

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which

Fig. 1 shows a cross-sectional view of a downhole annular base structure,
Fig. 2 shows a setting tool in a well,
Fig. 3 shows a cross-sectional view of the downhole annular base structure,
Fig. 4 shows a cross-sectional view of the setting tool,
Fig. 5 shows an enlarged cross-sectional view of the setting tool of Fig. 4,
Fig. 6 shows an enlarged cross-sectional view of another setting tool,
Fig. 7 shows part of a setting tool pushing an expandable element onto an expandable centre part before expanding the same,
Fig. 8 shows another setting tool arranged in a well,
Fig. 9 shows another downhole annular base structure,
Fig. 10 shows a sealing system in an open hole, and
Fig. 11 shows another sealing system in an open hole.

All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

Detailed description of the invention

Fig. 1 shows a downhole annular base structure 1 for being set downhole in an open hole part of a well in order to provide an annular base structure or a sealing structure abutting against an inner face of the open hole. The downhole annular base structure 1 may be set by means of a downhole setting tool 10 (shown in Fig. 2) arranged partly in a cased well part 2 and partly in an un-cased open hole part 3 in a well 4. The downhole annular base structure 1 of Fig. 1 has a longitudinal extension and comprises a first end part 6 having an indentation 7 in an inner face 8, in which indentation a sealing means 9 is arranged. The downhole annular base structure 1 comprises a second end part 11 which also has an indentation 12 in an inner face 14, and an expandable centre part 15 connected with the first and second end parts. The expandable centre part 15 has a wall thickness 16 which is smaller than those of the first and second end parts and is therefore capable of being expanded more easily than the first and second end parts.
The first end part is slidable in relation to the tool body along the longitudinal extension and the sealing means provides a sealing ability. The second end part 11 comprises a release element 17 engaging the indentation 12 for maintaining the second end part to the tool body along the longitudinal extension during positioning and/or expansion. In this way, the second end part is maintained in its position along the longitudinal extension, and the first end part is sliding towards the second end part as the centre part is expanded. The two end parts will, due to their increased thickness, stay unexpanded in the radial direction. As can be seen in Fig. 1, the tool has a tool body which together with the centre part and the end parts enclose a space 26. In order to expand the centre part, fluid is ejected through an outlet 42 in the tool body, and hence the space is pressurised.
In fig. 2, the setting tool 10 is shown in a well. The downhole annular base structure 1 is fastened to the second end 24 of the tool body 5 so that the downhole annular base structure 1 is not dropped when passing the vertical part of the well. The downhole annular base structure 1 extends into the second and open hole part 2 of the well, and part of the setting tool 10 is still in the cased part of the well. The setting tool 10 is connected and powered through a wireline 43. The setting tool is operated from surface or may be programmed to be self-operable. The setting tool uses pressurised fluid for expanding the downhole annular base structure 1, which is provided by a pump 44 driven by a motor 45 and an electronic section 46. The tool 10 further comprises a fluid control section 47 to control the pressurisation of the downhole annular base structure 1.
As shown in Fig. 3, the downhole annular base structure according to claim 1 further comprises an expandable element 18 arranged outside the outer face 22 of the centre part. The expandable element 18 has a wall thickness 19 which is larger than that of the centre part 15 and is made of a material which is more flexible than that of the centre part, so that the expandable element 18 is able to compensate for an uneven open hole. The expandable element has a first end 20 and a second end 21 and is adapted to be arranged on an outer face 22 of the centre part by the tool shown in Fig. 2. In Fig. 2, the expandable element 18 and the centre part are arranged in succession along the longitudinal extension, and a piston 30 is adapted to push the expandable element onto the outer face of the centre part before expanding the downhole annular base structure 1, so that the expandable element abuts the inner wall of the open hole.
The centre part is made of metal, such as steel, and the first and second end parts are made of metal, such as aluminium. The first and second end parts are substantially more rigid and taper towards the centre part from a base facing the tool body. The first and second end parts have indentations comprising a sealing element to seal the cavity to be pressurised. The centre part is arranged between the first and second end parts and may be connected with the first and second end parts by means of welding, such as friction welding.
The release element 17 projects from the inner face 14 of the second end part 11. The release element 17 engaging the indentation 12 also engages a radial bore 27 arranged in the second end 24 of the tool body for maintaining the second end part 11 to the tool body during positioning and/or expansion. The downhole annular base structure 1 is released when the pressurised fluid in the fluid channel 28 in the tool body 5 presses a second piston 37 arranged in the fluid channel towards the second end 24 of the tool body. As the second piston moves, a cavity 39 in the piston is moved to be opposite the releasing element 17, and the releasing element enters into the cavity 39 and out of engagement with second end part of the downhole annular base structure 1. In order to move the piston, a shear disc 51 arranged in front or upstream of the second piston 37 must be broken. A reception bore 38 for reception of the releasing element is arranged in front of the shear disc, and when the second piston is in a second position arranging the cavity opposite the release element, the second piston is arranged in that reception bore.
In another embodiment, the second piston comprises two end discs having a first diameter, and the two end piston parts are arranged with a mutual distance and connected by an intermediate piston rod having a diameter which is smaller than the first diameter, creating the cavity.
As shown in Fig. 3, sealing means is arranged between the second piston and the fluid channel. The sealing means is arranged in an indentation in the indentation arranged in the second piston. A spring 68 may be arranged upstream of the second piston for ensuring that the second piston is pressed into the second position.
Fig. 4 shows a part of the setting tool in cross-section in which the expandable element 18 is shown before it is to be pushed onto the centre part. The tool comprises a piston 30 which is movable along the tool axis for pressing on the first end 20 of the expandable element to arrange the expandable element on the outer face of the centre part. The piston is arranged circumferenting the tool body and is forced towards the second end 24 of the tool body 5 by means of pressurised fluid in a second fluid channel 36. The pressurised fluid in the second fluid channel is indicated by the number "1", and the pressurised fluid flowing in the other fluid channel for expanding the downhole annular base structure 1 is indicated by the number "2". The piston has a flange 53 abutting the expandable element 18 and the tool body so that fluid from the second fluid channel 36 is pressed into an expandable space 55 between a flange 54 of the tool body and the flange 53.
As shown in details in Fig. 5, the tool body comprises a groove 33 extending along the tool axis, and the piston comprises a projecting element 32 adapted for engaging the groove. As the fluid presses the piston towards the second end of the tool body, the projecting element 32 prevents the piston from sliding off the tool body when the projecting element abuts the end of the groove. When the piston 30 has pushed the expandable element onto the centre part, the projecting element 32 abuts the second end of the groove 33. In Fig. 5, the projecting element is closest to the first end of the groove. When the expandable element has been arranged outside the centre part, the fluid control section shown in Fig. 2 lets the fluid into main fluid channel 28 and expansion of the centre part can be initiated.
In Fig. 6, the piston is arranged in the tool body. The piston has a first piston part 63 arranged in the second fluid channel 36 and connected with a second piston part by a piston rod. The second piston part 64 is arranged outside the second fluid channel and abuts the expandable element 18. The first piston part is annular and is arranged in an annular fluid channel being the second fluid channel. The first piston part divides the second fluid channel in a first channel part 61 and a second channel part 61. The fluid is let from the pump into the first channel part 61, forcing the first part 63 of the piston to move and thereby forcing the second piston part to press onto the expandable element 18.
In order to force the expandable element fully onto the centre part, the piston may have a slotted end flange 66 as shown in Fig. 7. The slotted end flange 66 is in Fig. 7 shown in its expanded position in which the expandable element has been pushed fully onto the centre part. An annular support 52 is arranged between the expandable element 18 and the slotted end flange, so that the slotted end flange does not dig into the expandable element. The annular support is made of a material which is less flexible than that of the expandable element, and may thus be made of Polytetrafluoroethylene (PTFE) or similar material which is better than the material of the expandable element, e.g. it may be made of rubber, to even out the pressure applied to it by the slotted end flange.
The expandable element may comprise friction enhancing elements of for instance embedded tungsten carbide, rock, stone, etc. in order to obtain a more firm grip into the inner wall of the open hole.
As shown in Fig. 8, the annular support 52 may also be arranged between the expandable element and the annular base structure, so that the expandable element does not rupture when forced onto the centre part. The setting tool further comprises a fluid chamber 67 in fluid communication with the pump. The fluid chamber comprises a chamber piston dividing the chamber into a first chamber part and second chamber part, the first chamber part comprising fluid and being in fluid communication with the pump. The second chamber part may comprise a spring and be filled with a gas, such as nitrogen, propane or the like or be in fluid communication with well fluid.
The setting tool may further comprise a driving unit, such as a downhole tractor. The setting tool may further comprise an acid chamber so that after expansion of the centre part, the first and second end parts are removed by injecting acid into the well. The first and second end parts may also be removed by a machining tool 69, such as a milling tool or drilling tool. The machining tool 69 is arranged in front of the downhole annular base structure 1.
In Fig. 9, the expandable element comprises a plurality of annular elements 18' arranged in succession of each other in the longitudinal extension. Hereby, the annular elements are made of different materials having different characteristics, such as resistance to high temperatures, high pressure, acid, etc.
The release element may comprise a charge for detonation or be a shear pin.
Fig. 10 shows a downhole sealing system for sealing off a zone in an open hole well and comprises a first and a second downhole annular base structure set by the downhole setting tool. The annular base structures are set and expanded with a mutual distance, and a tubular element 41 has a first and a second tubular end and is arranged between the two annular base structures, so that the first tubular end overlaps the first annular base structure, and the second tubular end overlaps the second annular base structure, the tubular element having an outer face. In Fig. 10, the tubular element is expanded so that the outer face abuts an inner face of the annular base structures. In Fig. 11, packers are arranged between the tubular element 41 and the downhole annular base structures so that the tubular element does not need to be expanded.
The annular base structure according to the present invention may be set by a setting method for setting an annular base structure as described above in a well having a first well part with a casing string and a second well part without a casing string, the second well part having an inner diameter which is larger than that of the casing string.
This method comprises the steps of arranging the annular base structure on the tool body of the downhole setting tool as described above, moving the setting tool through the casing string until the annular base structure is arranged in the second well part, pressurising the fluid channel, expanding the annular base structure, releasing the tool body from the second end part and then retracting the setting tool.
The step of releasing the tool body from the second end part is performed before, during or after the step of expanding. In this method, before the step of expanding, the expandable element is arranged on the outer face of the centre part. The setting method may also comprise the step of removing the end parts, which may be performed by milling or by means of acid.
By fluid or well fluid is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By gas is meant any kind of gas composition present in a well, completion, or open hole, and by oil is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil, and water fluids may thus all comprise other elements or substances than gas, oil, and/or water, respectively.
By a casing is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.
In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.
Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

Claims

A downhole annular base structure (1) for being set downhole in an open hole part (3) of a well (4) by means of a downhole setting tool (10) having a tool body (5), the annular base structure having a longitudinal extension, comprising
- a first end part (6) having an indentation (7) in an inner face (8), in which indentation a sealing means (9) is arranged so that the first end part is slidable in relation to the tool body along the longitudinal extension,

- a second end part (11) having an indentation (12) in an inner face (14), and

- an expandable centre part (15) having a wall thickness (16) which is smaller than those of the first and second end parts,
wherein the second end part (11) comprises a release element (17) engaging the indentation (12) for maintaining the second end part to the tool body along the longitudinal extension during positioning and/or expansion.
A downhole annular base structure according to claim 1, further comprising an expandable element (18) having a wall thickness (19) which is larger than that of the centre part (15), the expandable element having a first end (20) and second end (21) and being adapted to be arranged on an outer face (22) of the centre part.
A downhole annular base structure according to claim 2, wherein the expandable element (18) is made of a material which is more flexible than the material of the centre part (15).
A downhole annular base structure according to any of the preceding claims, wherein the release element (17) projects from the inner face (14) of the second end part (11).
A downhole annular base structure according to claim 2, wherein the expandable element comprises a plurality of annular elements (18') arranged in succession of each other in the longitudinal extension.
A downhole setting tool (10) for setting an annular base structure (1) according to any of the preceding claims in a well having a first well part with a casing string and a second well part without a casing string, the second well part having an inner diameter which is larger than that of the casing string, comprising
- a tool body (5) having a tool axis, a first end (23), a second end (24) and an outer face (25), and

- an annular base structure (1) according to any of the preceding claims, the first and second end parts (6, 11) abutting the outer face of the tool body and hence defining a space (26) between the centre part (15) and the tool body (5),
wherein the release element engages a radial bore (27) arranged in the second end (24) of the tool body for maintaining the second end part (11) to the tool body during positioning and/or expansion.
A downhole setting tool according to claim 6, wherein the tool body (5) comprises a fluid channel (28) with an outlet (42) in fluid communication with the space (26) for expanding the annular base structure by means of pressurised fluid.
A downhole setting tool according to claims 6 or 7, wherein the expandable element and the annular base structure are arranged in succession along the tool axis.
A downhole setting tool according to any of the claim 6-8, wherein the tool body comprises a piston (30) which is movable along the tool axis for pressing on the first end of the expandable element to arrange the expandable element on the outer face of the centre part.
A downhole setting tool according to claim 9, wherein a second piston (37) is arranged in the fluid channel in the second end of the tool body opposite the second end part, the second piston having a cavity (39) for reception of the release element when the second piston is in a second position, providing the cavity opposite the release element.
A downhole setting tool according to any of the claims 7-10, further comprising a pump for pressurising fluid supplied through the fluid channel.
A downhole setting tool according to claim 11, further comprising a fluid chamber in fluid communication with the pump.
A downhole sealing system for sealing off a zone in an open hole well comprising
- a first and a second annular base structure according to any of the claims 1-5 set by the downhole setting tool according to any of claims 6-12, the annular base structures being set and expanded with a mutual distance, and

- a tubular element having a first and a second tubular end and being arranged between the two annular base structures, so that the first tubular end at least partly overlaps the first annular base structure, and the second tubular end at least partly overlaps the second annular base structure, the tubular element having an outer face,
wherein the tubular element is expanded so that the outer face abuts against an inner face of the annular base structures.
A downhole sealing system for sealing off a zone in an open hole well, comprising
- a first and a second annular base structure according to any of the claims 1-5 set by the downhole setting tool according to any of claims 6-12, the annular base structures being set and expanded with a mutual distance,

- a tubular element having a first and a second tubular end and being arranged between the two annular base structures, so that the first tubular end at least partly overlaps the first annular base structure, and the second tubular end at least partly overlaps the second annular base structure, the tubular element having an outer face, and

- two packers arranged between the annular base structures and the tubular element.
A setting method for setting an annular base structure according to any of the claims 1-5 in a well having a first well part with a casing string and a second well part without a casing string, the second well part having an inner diameter which is larger than that of the casing string, said setting method comprising the steps of:
- arranging the annular base structure on the tool body of the downhole setting tool according to any of the claims 6-12,

- moving the setting tool through the casing string until the annular base structure is arranged in the second well part,

- pressurising the fluid channel,

- expanding the annular base structure,

- releasing the tool body from the second end part, and

- retracting the setting tool,
wherein the step of releasing the tool body from the second end part is performed before, during or after the expansion step.