US20090205842A1

US20090205842A1 - On-site assemblable packer element for downwell packing system

Info

Publication number: US20090205842A1
Application number: US12/366,793
Authority: US
Inventors: Peter Williamson; Andreas Lutz
Original assignee: Stowe Woodward LLC
Current assignee: Stowe Woodward LLC
Priority date: 2008-02-15
Filing date: 2009-02-06
Publication date: 2009-08-20

Abstract

A packer system for a wellbore includes: a tubular member; a packer element mounted on the tubular member and formed of a swellable polymeric material; and a securing unit that is configured to enable the position of the packer element to be adjusted relative to the tubular member when the securing unit is in an unsecured condition, but secures the packer element in place when the securing unit is in a secured condition.

Description

RELATED APPLICATION

The present application claims priority from U.S. Provisional Patent Application No. 61/028,989, filed Feb. 15, 2008, the disclosure of which is hereby incorporated herein in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to a wellbore system for oil exploration, and more particularly to a packer for a wellbore system.

BACKGROUND OF THE INVENTION

A downhole wellbore system typically includes a pipe or other tubular structure that extends into a borehole drilled into the ground. In some instances, a casing is inserted into the wellbore to define its outer surface; in other instances, the rock or soil itself serves as the wall of the wellbore.
Many wellbore systems include a packer, which is designed to expand radially outwardly from the pipe against the walls of the wellbore. The packer is intended to seal segments of the pipe against the wellbore in order to isolate some sections of the wellbore from others. For example, it may be desirable to isolate a section of the formation that includes recoverable petroleum product from an aquifer.
Known sealing members for packers include, for example, mechanical packers which are arranged in the borehole to seal an annular space between a wellbore casing and a production pipe extending into the borehole. Such a packer is radially deformable between a retracted position, in which the packer is lowered into the borehole, and an expanded position, in which the packer forms a seal. Activation of the packer can be by mechanical or hydraulic means. One limitation of the applicability of such packers is that the seal surfaces typically need to be well defined, and therefore their use may be limited to wellbores with casings. Also, they can be somewhat complicated and intricate in their construction and operation. An exemplary mechanical packer arrangement is discussed in U.S. Pat. No. 7,070,001 to Whanger et al., the disclosure of which is hereby incorporated herein in its entirety.
Another type of annular seal member is formed by a layer of cement arranged in an annular space between a wellbore casing and the borehole wall. Although in general cement provides adequate sealing capability, there are some inherent drawbacks such as shrinking of the cement during hardening, which can result in de-bonding of the cement sheath, or cracking of the cement layer after hardening.
Additional annular seal members for packers have been formed of swellable elastomers. These elastomers expand radially when exposed to an activating liquid, such as water (often saline) or hydrocarbon, that is present in the wellbore. Exemplary materials that swell in hydrocarbons include ethylene propylene rubber (EPM and EPDM), ethylene-propylene-diene terpolymer rubber (EPT), butyl rubber, brominated butyl rubber, chlorinated butyl rubber), chlorinated polyethylene, neoprene rubber, styrene butadiene copolymer rubber (SBR), sulphonated polyethylene, ethylene acrylate rubber, epichlorohydrin ethylene oxide copolymer, silicone rubbers and fluorsilicone rubber. Exemplary materials that swell in water include starch-polyacrylate acid graft copolymer, polyvinyl alcohol cyclic acid anhydride graft copolymer, isobutylene maleic anhydride, acrylic acid type polymers, vinylacetate-acrylate copolymer, polyethylene oxide polymers, carboxymethyl cellulose type polymers, starch-polyacrylonitrile graft copolymers and the like and highly swelling clay minerals such as sodium bentonite. Exemplary swellable packers are discussed in U.S. Pat. No. 7,059,415 to Bosma et al. and U.S. Patent Publication No. 2007/0056735 to Bosma et al., the disclosure of each of which is hereby incorporated herein in its entirety.
Packer systems are typically assembled remotely from the wellbore, i.e., the packer elements are fixed to the underlying pipe or tube according to predetermined measurements. However, it may be desirable to provide a packer system that allows on-site adjustment of the positions of the packer elements on the pipe to address variable conditions in the wellbore. It may also be desirable to provide a system that enables the length of the packer to be adjusted on-site.

SUMMARY OF THE INVENTION

As a first aspect, embodiments of the present invention are directed to packer element units for wellbores. Such a packer element unit comprises: a generally annular packer element having an external surface, the packer element being formed of a swellable polymeric material; and a tightening band circumscribing the external surface of the packer element, the tightening band being configured to apply radially inward compression to the packer element to secure the packer element on a tubular member. In this configuration, the location of the packer element relative to the tubular member can be adjusted, particularly on-site of the wellbore, to enable the packer system to be adjusted based on conditions in the wellbore.
As a second aspect, embodiments of the present invention are directed to a packer system, comprising: a tubular member; a packer element mounted on the tubular member and formed of a swellable polymeric material; and a securing unit that is configured to enable the position of the packer element to be adjusted relative to the tubular member when the securing unit is in an unsecured condition, but secures the packer element in place when the securing unit is in a secured condition.
As a third aspect, embodiments of the present invention are directed to a packer system for a wellbore, comprising: a tubular member; a packer element mounted on the tubular member and formed of a swellable polymeric material; a securing end cap configured such that its position relative to the tubular member can be adjusted and secured. In this embodiment, the end cap can be adjusted to position the packer elements at desired locations on the tubular member.
As a fourth aspect, embodiments of the present invention are directed to a method of assembling a packer system. The method comprises the steps of: determining a desired level for a packer element within a wellbore based on conditions in the wellbore; positioning the packer element on a tubular member based on the determining step; securing the packer element on the tubular member to form a packer system; and positioning the packer system into the wellbore such that the packer element is located at the desired level determined in the determining step.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic side view of a packer system according to embodiments of the present invention.

FIGS. 2-4 are schematic side views showing steps in the assembly process of the packer system of FIG. 1.

FIG. 5 is an enlarged schematic side view of the packer system of FIG. 1 showing a tightening ring installed on the endmost packer element.

FIG. 6 is an enlarged schematic side view of a packer system according to alternative embodiments of the present invention showing an end cap installed adjacent the endmost packer element.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention will now be described more fully hereinafter, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.
In addition, spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Well-known functions or constructions may not be described in detail for brevity and/or clarity.
Turning now to the figure, a downwell pipe assembly, designated broadly at 20, is shown in FIG. 1. The assembly 20 is inserted into a wellbore, which is defined by walls in the earth. In some embodiments the assembly 20 may be disposed within a casing or other annular member that is inserted in the earth, or it may be inserted directly into the earth. In addition, the wellbore may be substantially vertically disposed, substantially horizontally disposed or disposed at any angle typically used for wells. As used herein, the term “wellbore” is intended to encompass any of these scenarios.
A packer system 30 is mounted to a segment of a base pipe 22. The packer system 30 includes a plurality of annular packer elements: in the illustrated embodiment, the system 30 includes a center element 32, two intermediate elements 34 that sandwich the center element 32, and two end elements 36 that sandwich the intermediate elements 34. In the illustrated embodiment, the elements 32, 34, 36 abut each other; however, in some embodiments gaps may exist between some or all of the elements.
The elements 32, 34, 36 are formed of a material, typically an elastomer, that swells when contacted with a swelling fluid. Most common swelling fluids include water and hydrocarbons. The elements 32, 34, 36 thus typically comprise materials that are selected for their ability to swell when in contact with water or hydrocarbon, depending on the projected location of the packer system 30 within the wellbore 10. Exemplary elastomeric materials that swell in hydrocarbons include ethylene propylene rubber (EPM and EPDM), ethylene-propylene-diene terpolymer rubber (EPT), butyl rubber, brominated butyl rubber, chlorinated butyl rubber), chlorinated polyethylene, neoprene rubber, styrene butadiene copolymer rubber (SBR), sulphonated polyethylene, ethylene acrylate rubber, epichlorohydrin ethylene oxide copolymer, silicone rubbers and fluorsilicone rubber. Exemplary elastomeric materials that swell in water include starch-polyacrylate acid graft copolymer, polyvinyl alcohol cyclic acid anhydride graft copolymer, isobutylene maleic anhydride, acrylic acid type polymers, vinylacetate-acrylate copolymer, polyethylene oxide polymers, carboxymethyl cellulose type polymers, starch-polyacrylonitrile graft copolymers and the like.
The swellable elastomer may also include fillers and additives that enhance its manufacturing or performance properties and/or reduce its costs. Exemplary filler materials include inorganic oxides such as aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), magnesium oxide (MgO), calcium oxide (CaO), zinc oxide (ZnO) and titanium dioxide (TiO₂), carbon black (also known as furnace black), silicates such as clays, talc, wollastonite (CaSiO₃), magnesium silicate (MgSiO₃), anhydrous aluminum silicate, and feldspar (KAlSi₃O₈), sulfates such as barium sulfate and calcium sulfate, metallic powders such as aluminum, iron, copper, stainless steel, or nickel, carbonates such as calcium carbonate (CaCo₃) and magnesium carbonate (MgCo₃), mica, silica (natural, fumed, hydrated, anhydrous or precipitated), and nitrides and carbides, such as silicon carbide (SiC) and aluminum nitride (AlN). These fillers may be present in virtually any form, such as powder, pellet, fiber or sphere. Exemplary additives include polymerization initiators, activators and accelerators, curing or vulcanizing agents, plasticizers, heat stabilizers, antioxidants and antiozonants, coupling agents, pigments, and the like, that can facilitate processing and enhance physical properties.
The swelling elastomer may also include a swelling agent. In some embodiments, the swelling agent may be a sorbent for hydrocarbon. Also, in some embodiments the swelling agent may comprise polyethylene (particularly linear polyethylene) and/or other polymers, which may be combined with a hydrocarbon wax or the like. Other suitable swelling agents include thermoplastic polymer and copolymer mixtures and polyalphaolefins.
In some embodiments, the elements 32, 34, 36 may include a protective coating that is removed once the system 30 is inserted into the wellbore. The protective coating may be removed with a fluid that is present in the wellbore, or may be removed through the introduction of a non-naturally-occurring fluid or agent in the wellbore.
The elements 32, 34, 36 are constructed so as to be able to slide relative to the base pipe 22 when being inserted thereon (see FIGS. 2-4). This can be achieved by making the central opening in each of the elements slightly larger than the diameter of the pipe 22. As such, the elements 32, 34, 36 can be inserted onto the pipe 22 and moved relative thereto, which enables an operator to position the elements precisely on the pipe 22. The ability to move the elements 32, 34, 36 relative to the pipe 22 provides the operator with the capacity to determine a desired level for the packer elements 32, 34, 36 and to adjust the positions of the elements 32, 34, 36 to the desired level and secure them at that level, while on-site, to account for changing conditions in the wellbore, mismeasurement, and the like.
Moreover, the length of the overall packer system 30 may be adjusted on-site by including or omitting packer elements. For example, if it is determined that the system 30 should be greater in length than that provided by the five elements 32, 34, 36, additional elements can be added to the pipe 22 on-site.
Installation of the elements 32, 34, 36 on the pipe 22 can be understood from FIGS. 2-5. Starting with the base pipe 22 (FIG. 2), an endmost element 36 can be slid into position on the pipe (FIG. 3). In the illustrated embodiment, the endmost element includes a tightening ring 38 applied to an end portion of the endmost element 36. The tightening ring 38 can be applied in multiple ways. For example, it may be formed of a heat-shrinkable material, or it may be a band that can by tightened through mechanical means (e.g., a manual or pneumatic drive unit). With either of these techniques, the tightening band 38 radially compresses the element 36 to fix it in position on the base pipe 22 (FIG. 5). By fixing the positions of at least one endmost packer element 36 (and in most instances both endmost elements 36), the remaining elements can remain in position. Thus, additional elements 32, 34, 36 can be added to the pip 22 (FIG. 4). Of course, in other embodiments, all elements may be positioned on the pipe 22 prior to the securing of the endmost element 36. Also, other means of securing the endmost element, such as mechanical fasteners, adhesives or the like, may also be employed.
As another example for fixing the position of the elements 32, 34, 36 on the base pipe 22, as shown in FIG. 3, an end cap 40 can be fixed to the base pipe 22 to abut the endmost element 36. The end cap 40 can be fixed by any number of fixing techniques, including mechanical fasteners, adhesives, welding or the like. The end caps 40 can, in some embodiments, have a diameter that is slightly larger than the diameter of the elements 32, 34, 36 in order to protect the elements as the system 30 is being inserted into the wellbore. The end caps 40 may also be used in conjunction with a tightening ring 38. Like the tightening ring, the end cap 40 can be converted between a secured condition, in which the end cap 40 is fixed to the pipe 22, and an unsecured condition, in which the end cap 40 can moved relative to the pipe 22.
Those skilled in this art will appreciate that other embodiments may also be suitable. For example, the packer system 30 may be thicker at its center than toward its ends. For example, it may comprise multiple distinct elements of different diameters, a single tapered element, or even a single element with a “stepped” profile with sections of different diameters rather than being tapered, in order to enable the center region of the packer system to contact the walls of the wellbore prior to the end portions. Also, if multiple distinct elements such as elements 32, 34, 36 are employed, the materials of each may vary, often such that the system includes central elements that swell more rapidly. Of course, the numbers of elements may also vary depending on the environment of use.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.

Claims

1. A packer element unit for a packer system for a wellbore, comprising:

a generally annular packer element having an external surface, the packer element being formed of a swellable polymeric material; and

a tightening band circumscribing the external surface of the packer element, the tightening band being configured to apply radially inward compression to the packer element to secure the packer element on a tubular member.

2. The packer element unit defined in claim 1, wherein the swellable polymeric material is a hydrocarbon-swellable material.

3. The packer element unit defined in claim 2, wherein the hydrocarbon-swellable polymer is selected from the group consisting of: ethylene propylene rubber, ethylene-propylene-diene terpolymer rubber, butadiene rubber, brominated butadiene rubber, chlorinated butadiene rubber, chlorinated polyethylene, neoprene rubber, styrene butadiene copolymer rubber, sulphonated polyethylene, ethylene acrylate rubber, epichlorohydrin ethylene oxide copolymer, silicone rubbers and fluorsilicone rubber.

4. The packer element unit defined in claim 1, wherein the swellable polymer is a water-swellable polymer.

5. The packer element unit defined in claim 4, wherein the water-swellable polymer is selected from the group consisting of: starch-polyacrylate acid graft copolymers; polyvinyl alcohol cyclic acid anhydride graft copolymers; isobutylene maleic anhydride; acrylic acid type polymers, vinylacetate-acrylate copolymers; polyethylene oxide polymers; carboxymethyl cellulose type polymers; and starch-polyacrylonitrile graft copolymers.

6. A packer system for a wellbore, comprising:

a tubular member; and

a packer element mounted on the tubular member and formed of a swellable polymeric material; and

a securing unit that is configured to enable the position of the packer element to be adjusted relative to the tubular member when the securing unit is in an unsecured condition, but secures the packer element in place when the securing unit is in a secured condition.

7. The packer system defined in claim 6, wherein the securing unit comprises a tightening band that circumscribes the packer element.

8. The packer system defined in claim 6, wherein the swellable polymeric material is a hydrocarbon-swellable material.

9. The packer system defined in claim 8, wherein the hydrocarbon-swellable polymer is selected from the group consisting of: ethylene propylene rubber, ethylene-propylene-diene terpolymer rubber, butadiene rubber, brominated butadiene rubber, chlorinated butadiene rubber, chlorinated polyethylene, neoprene rubber, styrene butadiene copolymer rubber, sulphonated polyethylene, ethylene acrylate rubber, epichlorohydrin ethylene oxide copolymer, silicone rubbers and fluorsilicone rubber.

10. The packer system defined in claim 6, wherein the swellable polymer is a water-swellable polymer.

11. The packer system defined in claim 10, wherein the water-swellable polymer is selected from the group consisting of: starch-polyacrylate acid graft copolymers; polyvinyl alcohol cyclic acid anhydride graft copolymers; isobutylene maleic anhydride; acrylic acid type polymers, vinylacetate-acrylate copolymers; polyethylene oxide polymers; carboxymethyl cellulose type polymers; and starch-polyacrylonitrile graft copolymers.

12. A packer system for a wellbore, comprising:

a tubular member; and

a securing end cap configured such that its position relative to the tubular member can be adjusted and secured.

13. A method of deploying a packer system in a wellbore, comprising the steps of:

determining a desired level for a packer element within a wellbore based on conditions in the wellbore;

positioning the packer element on a tubular member based on the determining step;

securing the packer element on the tubular member to form a packer system; and

positioning the packer system into the wellbore such that the packer element is located at the desired level determined in the determining step.

14. The method defined in claim 13, wherein the securing step comprises tightening a tightening band that circumscribes the packer element to compress the packer element onto the tubular member.

15. The method defined in claim 13, wherein the securing step comprises securing an end cap to the tubular member.

16. The method defined in claim 13, wherein the packer element comprises a swellable polymer.

17. The method defined in claim 16, wherein the conditions in the wellbore determined in the determining step include the level of a liquid in the wellbore, and wherein the positioning step comprises positioning the packer element so that it will contact the liquid in the wellbore when the lowering step is performed.

18. The method defined in claim 17, wherein the swellable polymer is a water-swellable polymer.

19. The method defined in claim 17, wherein the swellable polymer is a hydrocarbon-swellable polymer.