The invention generally relates to a packer.
Hydrocarbon fluids, such as oil and natural gas, are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be completed before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of equipment and materials in or around the wellbore for conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, production of oil and gas can begin.
In such well completion operations, packers are used to prevent fluid flow through an annulus formed by a tubing within the well and the wall of the wellbore or a casing. The packer is generally integrally connected to the tubing, using, for example, means such as a threaded connection, a ratch-latch assembly, or a J-latch, all of which are well known in the art. The tubing/packer connection generally establishes the seal for the inner radius of the annulus. The seal for the outer radius of the annulus is generally established by a deformable element such as rubber or an elastomer. A compressive force is generally applied to the deformable element, causing it to extrude radially outward. The element extends from the outer portion of the packer to the wellbore wall or casing and seals between those structures.
In an embodiment of the invention, a packer that is usable with a well includes a resilient seal element and a support member. The resilient seal element is adapted to radially expand in response to the longitudinal compression of the element. The support member is at least partially surrounded by the seal element and is adapted to radially expand with the seal element to support the element. The support sleeve is substantially harder than the seal element.
In another embodiment of the invention, a technique that is usable with a well includes compressing a resilient seal element to cause the seal element to radially expand. The technique includes in concert with the radial expansion of the seal element, deforming a material that is substantially harder than the seal element to support the seal element.
Advantages and other features of the invention will become apparent from the following drawing, description and claims.
A packer is a device that is used in an oilfield well to form a seal for purposes of controlling production, injection or treatment. The packer is lowered downhole into the well in an unset state, and once in the appropriate position downhole, the packer is set, which means a seal of the packer radially expands to seal off an annular space. As an example, for a mechanically-set packer, a tubular string that extends from the surface to the packer may be moved pursuant to a predefined pattern to set the packer. For a hydraulically-set packer, fluid inside the tubular string may be pressurized from the surface, to create a tubing pressure differential to set the packer.
In its set state, the packer anchors itself to the casing wall of the well (or to the wellbore wall in an uncased or open well) and forms a seal in the annular region between the packer and the interior surface of the casing wall. This seal subdivides the annular region to form an upper annular region above the packer that is sealed off from a lower annular region below the packer. The packer also forms a seal for conduits that are inserted through the packer between the upper and lower annular regions. As examples, one of these conduits may communicate production fluid from a production zone that is located below the packer, one of the conduits may communicate control fluid through the packer, one of the conduits may house electrical wiring for a submersible pump, allow production or injection through two different reservoir zones, and so forth.
The packer 20 includes at least one seal assembly 24 to form the annular seal and at least one set of slips 22 to anchor the packer 20 to the casing string 12. In this manner, when run into the well, the seal assembly 24 and the slips 22 are radially retracted to allow passage of the packer 20 through the central passageway of the casing string 12. However, when the packer 20 is in the appropriate downhole position, the packer 20 is set to place the packer 20 in a state in which the seal assembly 24 and slips 22 are radially expanded. When radially expanded, the slips 22 grip the interior surface of the wall of the casing string 12 to physically anchor the packer 20 in position inside the well. The radial expansion of the seal assembly 24, in turn, seals off the annular space between the string 16 and the casing string 12 to form a sealed annular region above the seal assembly 24 and a sealed annular region below the seal assembly 24.
In some embodiments of the invention, the packer 20 may be hydraulically-actuated for purposes of controlling the packer 20 from the surface of the well to set the packer 20. This means that pressure may be communicated through fluid inside the string 16 to the packer 20. In response to this pressure reaching a predefined threshold level, pistons (not shown in
One or more mandrels 21, or tubular members, may extend through the packer 20 for purposes of providing communicating paths through the packer 20. Depending on the particular application of the packer 20, a particular mandrel 21 may contain one or more communication paths, such as paths to communicate production fluid, electrical lines, or control fluid through the packer 20. For example, in a particular application, a single mandrel 21 may extend through the packer 20 for purposes of communicating production fluid from a tubular string 23 located below the packer 20 to the string 16 located above the packer 20. However, in other applications, more than one mandrel 21 may be extended through the packer 20. Thus, one mandrel 21 may be used for purposes of communicating electrical or hydraulic lines, for example, and another mandrel 21 may be used for purposes of communicating production fluid through the packer 20.
The packer 20 may be retrievable, and thus may include a release mechanism that when engaged, releases the retention mechanism of the packer 20 to radially retract the slips 22 and seal assembly 24 to permit retrieval of the packer 20 to the surface of the well.
The packer 20 establishes two general seals: an interior seal between the interior of the packer 20 and the exterior of the one or more mandrels 21 that are extended through the packer 20 and an exterior seal between the exterior of the packer 20 and the interior surface of the wall of the casing string 12 (or the wellbore wall in alternative embodiments). The seal assembly 24 includes a resilient seal element (such as one or more elastomer or rubber sleeves, or rings) for establishing the seal between the packer exterior and the casing 12 (or wellbore wall).
In general, as the requirements for packer designs tend towards larger and larger inner diameters through the packer, the annular seal element of the packer is forced to become thinner and thinner. Additionally, there may also desire to cover multiple casing weights with one size of packer, leading to larger gaps that must be bridged off by the annular seal element. Bridging off a large gap with a thin element may be very difficult, unless the rubber is supported. Embodiments of the invention that are described herein include a packer that has a resilient seal element, which has a support that is fabricated from a hardened material.
In the context of this application, a “hardened material” means a material that has a substantially greater resistance to deformation relative to the seal element of the packer. For example, in some embodiments of the invention, the hardened material may be a metal that has substantially more resistance to deformation than an elastomer or rubber material that forms the seal element. Alternatively, in accordance with other embodiments of the invention, the hardened material may be a composite or plastic material, which has substantially more resistance to deformation that an elastomer or rubber material that forms the seal element. Furthermore, in accordance with other embodiments of the invention, the hardened material may be a combination of the above-mentioned materials. Thus, many variations are contemplated and are within the scope of the appended claims.
As a more specific example, for some embodiments of the invention, the hardened material is a soft metal, such as low carbon steel or copper, in accordance with some embodiments of the invention. However, in accordance with other embodiments of the invention, the hardened material may be a relatively resilient material. For example, in accordance with some embodiments of the invention, the hardened material may be a metallic spring material. Thus, many variations are possible and are within the scope of the appended claims.
In general, the seal assembly 24 includes a resilient seal element that may be formed from multiple seal sleeves, or rings, such as upper 56, middle 60 and lower 64 seal rings. The seal rings 56, 60 and 64 generally circumscribe the inner mandrel 16 of the packer 20 and may be formed from a rubber or an elastomer material (as examples). It is noted that the seal assembly 24 may include fewer or more seal rings, depending on the particular embodiment of the invention.
As also depicted in
In addition to the resilient seal element, the seal assembly 24 includes a hardened (relative to the seal rings 56, 60 and 64) support sleeve 80 that is located between the resilient seal element and the mandrel 16. As a more specific example, as depicted in
The support sleeve 80 may or may not be bonded to the middle seal ring 60, depending on the particular embodiment of the invention. For embodiments of the invention in which the support sleeve 80 is bonded to the middle seal ring 60, all or only part of the outer surface of the support sleeve 80 may be bonded to the inner surface of the middle seal ring 60. It is noted that depending on the particular embodiment of the invention, the support sleeve 80 may be bonded to all, part or none of the upper 56 and lower 64 seal rings.
In some embodiments of the invention, the support sleeve 80 includes an annular crimped section 82 at its longitudinal midpoint, which radially extends away from the outer surface of the mandrel 16. The crimped section 82 configures the support sleeve 80 to bend at the section 82 during the radial expansion of the seal assembly 24, as depicted in
Referring back to
Referring to
As also shown in
As yet another variation,
As yet another example,
Each of the rings 260 and 270 has a V-shaped cross-section and provides support to minimize longitudinal extrusion of the seal element (seal rings 56, 60 and 64) when the packer is set. More specifically, when the packer is set, the V-shaped rings 260 and 270 each flatten to be substantially horizontal and rise above the gauge diameter, thereby minimizing the extrusion gap and supporting the seal element.
While the present invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.
This application claims the benefit pursuant to 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 60/595,997 entitled, “PACKER ELEMENT WITH SUPPORT,” filed on Aug. 23, 2005, which is hereby incorporated in reference in its entirety.
Number | Date | Country | |
---|---|---|---|
60595997 | Aug 2005 | US |