Vibration-Resistant Seal for Downhole Tool
A seal ring assembly for a well drilling tool that takes the place of conventional O-rings that are prone to costly downhole failures. In a first embodiment the seal ring assembly is configured with a convex adapter seal ring at one end, a concave adapter seal ring at the other end, and a number of V-shaped component seal rings packed in between the convex and concave adapter seal rings and positioned in the space between a drill collar mandrel and a pressure cylinder of the well drilling tool. In a second embodiment the seal ring assembly is configured with a number of X-shaped component seal rings, each of which is fitted with two O-rings. The seal ring assemblies are able to flex when operating in a bent drill hole so as to maintain seal integrity and prevent fluids from passing through to the electronics region of the well drilling tool.
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1. Technical Field
Various embodiments of the present invention relate to well drilling equipment, and more specifically, to seals for downhole drilling tools.
2. Description of Related Art
Downhole oil well drilling tools are exposed to extreme heat, pressure, bending, shock, and vibration. A typical well tool has one or more seals, such as O-rings, located in various places to isolate pressurized fluid from an atmospheric region. For instance, seals are typically found between the drill collar mandrel and pressure cylinder. The O-ring is intended to keep fluids out of the well tool assembly containing electronic components that may be damaged by moisture or pressure-conveyed fluids. The seals are subjected to vibrations and mechanical stress in the extreme heat and pressures encountered as the well is being drilled. These extreme conditions in combination with the dynamic motion between the mandrel and sealing surface on the mating cylinder contribute to O-ring seal failures. For example, rotational bending can cause a gap to open and close between the conventional parts, letting liquid pass the seal. Conventional O-rings are prone to downhole failure due to these conditions, sometimes causing inaccurate equipment readings, electrical shorts, destruction of electronics and sensors, leading to costly work stoppages.
BRIEF SUMMARYVarious embodiments of the present invention involve a seal ring assembly for a well drilling tool which has a plurality of component seal rings, each with a V-shaped concave surface on one face generally parallel to the V-shaped convex surface on the opposite face. The rings have an external and internal cylindrical surface joining the V-shapes faces. The component seal rings are positioned between a convex adapter seal ring and a concave adapter seal ring. The convex adapter seal ring has a V-shaped inner surface that mates with the V-shaped concave surface of a first component seal ring. The concave adapter seal ring has a V-shaped inner surface that mates with the V-shaped convex surface of the last component seal ring. The seal ring assembly is positioned in coaxial alignment between a drill collar mandrel and a pressure cylinder of the well drilling tool. Seals may be made from a relatively flexible material such as reinforced rubber or plastic. The seal material is typically chosen to have properties suitable for the environment based upon the material's chemical resistance, extrusion resistance, thermal expansion, resiliency, and resistance to hardening due to temperature. Adapters are typically made from a relatively stiff material, e.g., a metal.
According to other embodiments, a seal ring assembly can comprise a plurality of X-shaped seal rings, each having an X-shaped cross-section and a predefined diameter, each of the plurality of X-shaped seal rings being configured with an inner lateral groove and an outer lateral groove. A plurality of first O-rings are each respectively configured to be received in the inner lateral groove of one of the plurality of X-shaped seal rings. A plurality of second O-rings are respectively configured to be received in the outer lateral groove of one of the plurality of X-shaped seal rings. The X-ring can be made from a relatively stiff material, but which is capable of deforming. The O-ring can be made from a more flexible material, such as rubber, to separate the function of sealing against fluids and supporting relative movement.
The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate various embodiments of the invention. Together with the general description, the drawings serve to explain the principles of the invention. In the drawings:
The well drilling tool sometimes experiences rotational bending when drilling in a curved borehole. The inventors believe that this dynamic motion causes the small gap to open and close in conventional O-ring seals, resulting in small amounts of liquid getting past the conventional O-ring seals as the tool flexes. In the inventors' experience the gap due to conventional O-rings changes in a cyclical manner according to the rate of drilling which is typically between 60 to 120 revolutions per minute. In addition to mechanical stresses due to bending when drilling, the downhole well drilling tools are also exposed to extreme heat, pressure, shock and vibration. These extreme conditions sometimes result in failure of the conventional seals intended to keep moisture away from the measurement devices and communication equipment in the well tool electronics region. Moisture breaching the seals can reach the electronics region of well drilling tool 101, causing data loss, electrical shorts or damage to components that cannot withstand exposure to fluid or pressure, errant readings or even complete failure of the tool. Various embodiments disclosed herein aid in preventing seal failures between the drill collar mandrel and pressure cylinder. The various embodiments replace conventional O-ring seals with a V-shaped seal ring assembly, sometimes called V-packing or V-packing seal assembly, to provide a seal between the drill collar mandrel and the pressure cylinder. It should be noted that some tool architectures have the drill collar interior to the seal, but other downhole tools have an internal component, often called a “chassis,” that inserts within and has the atmospheric chamber sealed to the drill collar inside diameter. The terms “piston” and “cylinder” may be used as more generalized terms that encompass “drill collar mandrel” and “pressure cylinder.” The V-packing seal assembly embodiments and various other various embodiments may be used in conjunction with other oilfield technology comprising wireline tools and coiled tubing conveyed tools, as well as devices requiring seals in a number of other fields such as aerospace, automotive, biomedical, marine and defense.
The well drilling tool 101 has a center axis 150 through the tool body as shown in
The chevron-shaped V-rings 105 of the V-shaped seal ring assembly help maintain a seal in situations where conventional O-ring seals, T-seals, and lip seals tend to fail. The chevron-shaped V-rings expand in response to compression, e.g., compression from a member designed to provide said compression, such as a threaded nut, and compression from the external pressure being sealed. In some tool architectures pressure may be exerted by a spring, forcing the part into an axial compression fit, or by loading via a drill string connection thread. This expansion of the V-packing acts to close the gaps that tend to form due to compression. The V-packing of the various embodiments helps to provide concentricity in addition to removing gaps, and also provides a radially-acting force to limit the relative movement between parts while the tool is subjected to flexing, vibrations, pressure, and thermal expansion due to outside mechanical stresses and pressures. The V-packing seal ring assembly helps to prevent seal failure in situations where the shaft moves axially in the cylinder in response to the rotational bending of well drilling. The V-packing seal ring assembly also helps to prevent seal failures in situations where the seal life is called on to extend for long periods of time. One example of a long life situation occurs in subsea safety valves having seals that are expected to last for years without failure.
The convex adapter seal ring 103 and concave adapter seal ring 107 of the seal ring assembly are typically made of a relatively stiff material, generally a metal or metal composite material. Depending upon the drilling conditions and particularities of the implementation the seal assembly may be made from an assortment of other materials. For example, in some embodiments parts of the seal assembly may be made from reinforced cloth materials (e.g., Kevlar), various polymer materials, lower modulus of elasticity metals such as copper and titanium, compounds such as nitrile, fluorocarbon elastomers, various rubber products, or other such materials known to those of ordinary skill in the art. The convex adapter seal ring 103 has a convex V-shaped profile that fits into the adjacent concave V-shaped component seal ring 105. At the other end of the assembly the concave adapter seal ring 107 has a concave V-shaped profile that accepts the convex surface of adjacent component seal ring 105.
On the outer surface of the assembly—that is, upper 113 and lower surface 117 on the ends of the assembly—the convex adapter seal ring 103 and concave adapter seal ring 107 each typically have a square faced surface to allow them to mate with similar disk surfaces of the components that capture the V-packing assembly. However, in some embodiments these outer surfaces 113, 117 of the convex adapter seal ring 103 and concave adapter seal ring 107 may have surfaces with angles other than perpendicular to the tool axis 150. They may, in some implementations, be sloped either upwards or downwards from the outer circumference edge inwards toward the tool axis 150, or they may have a shape other than a planar flat surface.
These V-packing seal assembly 103-107 are typically loaded axially with a threaded nut, the portion 109 of pressure cylinder 131. This expands the V-packing seal assembly 103-107 in a radial (outward) direction to aid in closing any gaps between the components. Additional loading typically occurs when the seal assembly is exposed to downhole pressures, temperatures and mechanical stresses. The seal expansion of the V-packing seal assembly components 103-107 tends to remove the gaps between components by applying a radial force to prevent relative movement.
Turning to
In the embodiment of
In the embodiment of
Note that although the afore-described exemplary embodiments provide for, among other things, a vibration resistant seal comprising a V-shaped ring, according to other exemplary embodiments the ring could have other shapes. For example, a C-shaped ring could alternatively be provided with a continuously varying angle.
As shown in
Various alternatives and other embodiments will also be apparent to those skilled in the art. For example, although the tool architecture described in the exemplary embodiments above provides for a drill collar interior to the seal, other downhole tools have an internal component, often called a “chassis”, that inserts therewithin and has the atmospheric chamber sealed to the drill collar internal diameter. The terms “piston” and “cylinder” can be considered as more general versions of “drill collar mandrel” and “pressure cylinder”.
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 comprising the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and “comprising” 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. The term “obtaining,” as used herein and in the claims, may mean either retrieving from a computer readable storage medium, receiving from another computer program, receiving from a user, calculating based on other input, or any other means of obtaining a datum or set of data. The term “plurality,” as used herein and in the claims, means two or more of a named element. It should not, however, be interpreted to necessarily refer to every instance of the named element in the entire device. Particularly, if there is a reference to “each” element of a “plurality” of elements. There may be additional elements in the entire device that are not in the “plurality” and are not, therefore, referred to by “each.”
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to comprise any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and gist of the invention. The various embodiments herein were chosen and described in order to explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
Claims
1. A seal ring assembly, comprising:
- one or more component seal rings each having a V-shaped concave surface and a V-shaped convex surface;
- a convex adapter seal ring with a V-shaped inner surface configured to mate with the V-shaped concave surface of a first one of said one or more component seal rings; and
- a concave adapter seal ring with a V-shaped inner surface configured to mate with the V-shaped convex surface of a second one of said one or more component seal rings;
- wherein said one or more component seal rings are positioned between the convex adapter seal ring and the concave adapter seal ring.
2. The seal ring assembly of claim 1, wherein the convex adapter seal ring, the concave adapter seal ring, and said one or more component seal rings each have a first lateral side surface positioned adjacent an inner shaft of a well drilling tool and a second lateral side surface positioned adjacent an outer bore of said well drilling tool.
3. The seal ring assembly of claim 1, wherein the inner shaft is a drill collar mandrel and the outer bore is a pressure cylinder, and wherein the concave adapter seal ring further comprises:
- a groove configured on the V-shaped inner surface.
4. The seal ring assembly of claim 1, wherein the inner shaft is a chassis and the outer bore is a drill collar, and wherein the concave adapter seal ring further comprises:
- a groove configured on the V-shaped inner surface.
5. The seal ring assembly of claim 1, wherein said one or more component seal rings each have a concave surface chevron angle that differs from a convex surface chevron angle.
6. The seal ring assembly of claim 1, wherein the convex adapter seal ring has a first planar outer surface perpendicular to a center axis of a well drilling tool; and
- wherein the concave adapter seal ring has a second planar outer surface perpendicular to said center axis of the well drilling tool.
7. The seal ring assembly of claim 6, wherein the well drilling tool has an element configured to exert pressure against either the first planar outer surface or the second planar outer surface.
8. The seal ring assembly of claim 7, wherein said element is one of a threaded nut, a spring, and a drill string connection thread.
9. A well drilling tool, comprising:
- a drill collar mandrel;
- a pressure cylinder;
- one or more component seal rings each having a V-shaped concave surface and a V-shaped convex surface;
- a convex adapter seal ring with a V-shaped inner surface configured to mate with the V-shaped concave surface of a first one of said one or more component seal rings; and
- a concave adapter seal ring with a V-shaped inner surface configured to mate with the V-shaped convex surface of a second one of said one or more component seal rings;
- wherein said one or more component seal rings are positioned between the convex adapter seal ring and the concave adapter seal ring.
10. The well drilling tool of claim 9, wherein the convex adapter seal ring, the concave adapter seal ring, and said one or more component seal rings each have a first lateral side surface positioned adjacent said drill collar mandrel and a second lateral side surface positioned adjacent said pressure cylinder.
11. The well drilling tool of claim 9, wherein the concave adapter seal ring further comprises:
- a groove configured on the V-shaped inner surface.
12. The well drilling tool of claim 9, wherein said one or more component seal rings each have a concave surface chevron angle that differs from a convex surface chevron angle.
13. The well drilling tool of claim 9, wherein the convex adapter seal ring has a first planar outer surface perpendicular to a center axis of the well drilling tool; and
- wherein the concave adapter seal ring has a second planar outer surface perpendicular to said center axis of the well drilling tool.
14. The well drilling tool of claim 13, wherein the well drilling tool has a mechanism configured to exert pressure against either the first planar outer surface or the second planar outer surface.
15. The well drilling tool of claim 14, wherein said mechanism is one of a threaded nut, a spring, and a drill string connection thread.
16. A seal ring assembly, comprising:
- a plurality of X-shaped seal rings each having an X-shaped cross-section and a predefined diameter, each of said plurality of X-shaped seal rings being configured with an inner lateral groove and an outer lateral groove;
- a plurality of first O-rings each being respectively configured to be received in the inner lateral groove of one of said plurality of X-shaped seal rings; and
- a plurality of second O-rings each being respectively configured to be received in the outer lateral groove of one of said plurality of X-shaped seal rings.
17. The seal ring assembly of claim 16, wherein said plurality of first O-rings each has a mean diameter smaller than said predefined diameter, and said plurality of second O-rings each has a mean diameter larger than said predefined diameter.
18. The seal ring assembly of claim 17, wherein said plurality of first O-rings are configured to be positioned adjacent a drill collar mandrel of a well drilling tool, and said plurality of second O-rings are configured to be positioned adjacent a pressure cylinder of the well drilling tool.
19. The seal ring assembly of claim 17, wherein said plurality of first O-rings are configured to be positioned adjacent a chassis of a well drilling tool, and said plurality of second O-rings are configured to be positioned adjacent a drill collar of the well drilling tool.
20. The seal ring assembly of claim 1, wherein said seal assembly operates to close an extrusion gap, support against radial forces and transfer loading from axial force to radial force.
Type: Application
Filed: Dec 22, 2010
Publication Date: Jun 28, 2012
Applicant: SONDEX LIMITED (Yately)
Inventors: David Blaine AYERS (Sugar Land, TX), Ashwin GUPTE (Sugar Land, TX)
Application Number: 12/975,643
International Classification: E21B 10/00 (20060101);