WO2013152033A1

WO2013152033A1 - Energized bushing seal

Info

Publication number: WO2013152033A1
Application number: PCT/US2013/035012
Authority: WO
Inventors: Jack Allen
Original assignee: Array Holdings, Inc.
Priority date: 2012-04-02
Filing date: 2013-04-02
Publication date: 2013-10-10

Abstract

A bushing and wellhead spool with a single injection port allowing a method of delivering sealing media to mechanical seals of a bushing is disclosed.

Description

ENERGIZED BUSHING SEAL

FIELD

[0001] The invention generally relates to bushings. More specifically, the invention relates to bushings used in wellheads within a casing or tubing spool wherein mechanical seals are used.

BACKGROUND

[0002] A wellhead is a series of fittings that attach to pipe or suspend then seal pipe strings in order to allow surface control of a well.

[0003] After a well section has been drilled, it is generally necessary to secure a borehole of the well section by lining it with a pipe known as oilfield casing. Within such an aforementioned wellhead, casing heads, tubing head spools and casing spools can possess bushings for rotation. A wear bushing is used in drilling applications to protect the inner profiles of the various components in the wellhead.

[0004] Sitting atop the well is the wellhead. In a typical wellhead, positioned from a position proximal or towards the well is a wellhead support plate. Distal to the wellhead support plate is a casing head housing, a threaded outlet connection and a casing hanger. Distal to the casing hanger is an annular casing packoff. Distal to the casing packoff is a double studded adapter followed by a tubing head spool. Distal to the tubing head spool is a bottom casing packoff. Above or distal to the bottom casing packoff is a studded side outlet and extended neck tubing hangar with a down hole safety valve control line. Distal to the safety valve control line in many embodiments is a tubing head adapter and a back pressure valve preparation followed by a subsurface safety valve control line outlet.

[0005] The packoffs of the wellhead such as the tubing hanger packoff, the bottom casing packoff and the annular casing packoff in certain embodiments incorporate bushings. In these instances, the bushings can be used to seal pipe streams and isolate them from other streams. [0006] Bushings are also used in a variety of petroleum applications, including drilling and casing operations.

[0007] In certain instances, it is necessary to coat bushings with sealing media so as to isolate production streams.

[0008] The design herein enclosed eliminates the need for two ports to inject sealing media to energize mechanical seals on oilfield casing and/or tubing. The sealing media is injected through one port. This allows the sealing media to energize the seals to a specific pressure against the casing or tubing OD to contain the pressure of the oil or gas well. This modification results in time savings in the field for installation of the equipment. This also eliminates the problem of locating two ports (one for each of the seals) when the flange thickness in some flanges is insufficient for two ports.

SUMMARY

[0009] Certain embodiments of the invention disclosed herein pertain to a wellhead spool such as a casing spool or a tubing spool. In such embodiments, the spool further comprises a wellhead spool casing having an inward facing wall having a distal end oriented away from a wellhead and a proximal end oriented toward a wellhead; the inward facing wall of the wellhead spool forming a wellhead spool cavity adapted to receive a bushing, the wellhead spool further defining a central axis.

[0010] In such embodiments, the wellhead spool further comprises a bushing having an outward facing wall and an inward facing wall, the inward facing wall defining a bushing bore, the bushing being positioned within the wellhead spool cavity; an injection port traversing from an exterior of the wellhead spool to the wellhead spool cavity; and at least one mechanical seal within the bushing bore, the bushing bore circumscribing the at least one mechanical seal. In such embodiments sealing media is injected into the injection port and contacts the at least one mechanical seal.

[0011] Still further, in certain embodiments the wellhead spool has at least one sealing media passage fluidly connecting the at least one mechanical seal to the wellhead spool cavity. Likewise, in certain embodiments, the wellhead spool has a plurality of sealing media passages. [0012] In additional embodiments the at least one sealing media passage is parallel to the central axis. In such embodiments the at least one mechanical seal abuts the at least one sealing media passage.

[0013] Further, regarding the bushing, the bushing has at least one annular groove abuts the inner wall of the bushing. Still further, in many embodiments the at least one annular grooves circumscribe the mechanical seals. In other embodiments the bushing has a plurality of annular grooves.

[0014] In embodiments of the aforementioned invention concerning the at least one sealing passage and the at least one annular groove, the sealing media passage is in fluid connection with the at least one annular groove and wherein the injection port is in fluid connection with the at least one annular groove.

[0015] In further embodiments regarding the mechanical seal, the mechanical seal is an elastomeric mechanical seal.

[0016] In particular embodiments of the invention regarding the material used to create the spool casing; the spool casing is stainless steel.

[0017] Other embodiments of the invention pertain to a method of sealing the wellhead spool of as described above, comprising injecting a sealing media into the injection port. Still further, in certain embodiments the sealing media flows into the at least one annular groove.

[0018] Likewise, in such embodiments the sealing media flows from the at least one sealing media passage into the at least one annular groove. Further, the media contacts the at least one mechanical seal.

[0019] Additional embodiments concern the sealing media. In certain embodiments, the sealing media hardens upon flowing from the injection port to the at least one mechanical seal. In other embodiments, the sealing media remains a liquid. In further embodiments, the sealing media comprises a fluoropolymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order that the manner in which the above-recited and other enhancements and objects of the invention are obtained, we briefly describe a more particular description of the invention briefly rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope, we herein describe the invention with additional specificity and detail through the use of the accompanying drawings in which:

[0021] Fig. 1 is an illustration of a typical wellhead;

[0022] Fig. 2 is a cross sectional illustration of a casing or tubing spool; and

[0023] Fig. 3 is a cross sectional illustration of the bushing.

List of Reference Numerals

[0024] 10 casing or tubing spool

[0025] 15 central axis

[0026] 20 injection port for sealing media

[0027] 30 ports for sealing media passage

[0028] 35 lateral passages

[0029] 40 mechanical seals

[0030] 50 bushing

[0031] 60 annular groove

[0032] 70 casing spool cavity

[0033] 80 wellhead [0034] 90 tubing head spool

[0035] 100 wellhead support plate

DETAILED DESCRIPTION

[0036] We show the particulars shown herein by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only. We present these particulars to provide what we believe to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, we make no attempt to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention. We indent that the description should be taken with the drawings. This should make apparent to those skilled in the art how the several forms of the invention are embodied in practice.

[0037] We mean and intend that the following definitions and explanations are controlling in any future construction unless clearly and unambiguously modified in the following examples or when application of the meaning renders any construction meaningless or essentially meaningless. In cases where the construction of the term would render it meaningless or essentially meaningless, we intend that the definition should be taken from Webster's Dictionary 3^rd Edition.

[0038] As used herein, the term "pipe" means and refers to a fluid flow path.

[0039] As used herein, the term "conduit" means and refers to a fluid flow path.

[0040] As used herein, the term "line" means and refers to a fluid flow path.

[0041] As used herein, the term "fluid" refers to a non-solid material such as a gas, a liquid or a colloidal suspension capable of being transported through a pipe, line or conduit. Examples of fluids include by way of non-limiting examples the following: natural gas, propane, butane, gasoline, crude oil, mud, water, nitrogen, sulfuric acid and the like.

[0042] As used herein, the term "attached," or any conjugation thereof describes and refers to the at least partial connection of two items. [0043] As used herein, the term "proximal" refers to a direction toward the center of the ball valve.

[0044] As used herein, the term "distal" refers to a direction away from the center of the ball valve.

[0045] As used herein, slidably connected referrers to one component abutting another component wherein one component is capable of moving in a proximal or distal direction relative to the other component.

[0046] The embodiments herein pertain to an improved bushing for use in energizing mechanical seals on oilfield casing or oilfield tubing.

[0047] In certain embodiments of the invention, the bushing has one port for injecting sealing media. In other embodiments of the invention, the busing has multiple ports for injecting sealing media.

[0048] In embodiments concerning the injection of sealing media, the interior of the bushing may possess a plurality of passages to allow passage of the sealing media. In further embodiments, the plurality of passages in the interior of the bushing is fluidly connected to at least one interior annular groove.

[0049] Further, it is contemplated that the bushing possesses at least one mechanical seal. In such embodiments, injected sealing media flows through an injection port to at least one annular groove.

[0050] In embodiments wherein the sealing media flows into at least one annular groove, the at least one annular groove is fluidly connected to at least one interior passage as described above. In such embodiments, the at least one interior passage is fluidly connected to at least one mechanical seals.

[0051] Upon entry of the sealing media into the at least one interior passage, the sealing media travels to the at least one annular groove. In such embodiments, the sealing media further travels to at least one mechanical seals. [0052] In certain embodiments, there are two interior passages. In further embodiments, there are 3, 4, 5, 6, 7, 8, 9, or 10 interior passages.

[0053] In embodiments of the invention concerning the annular groove, the injection port is fluidly connected to at least one annular groove. In further embodiments the injection port is fluidly connected to more than one annular groove. In further embodiments concerning the annular grooves, the annular grooves circumscribe the mechanical seals. In other embodiments, the annular grooves partially circumscribe the mechanical seals.

[0054] In certain embodiments concerning the mechanical seals, the mechanical seals are elastomeric seals. Such seals include but are not limited to nitrile seals, Viton ® seals, fluoropolymer seals and the like.

[0055] In embodiments of the invention concerning the sealing media, the sealing media is any injectable media. Injectable media in many embodiments is a plastic type packing material capable of being injected. In certain examples, the compounds comprise impregnated Teflon. Examples of brands of injectable sealing media include the Desco TM brand of injectable packing. In certain embodiments the sealing media is designed to withstand pressures of 1 bar to 1000 bar or a numerical value therein. In other embodiments the sealing media is designed to withstand temperatures from -80°C to 800 °C. In certain applications, the sealing media is designed to withstand high oxygen environments. In other embodiments, the sealing media is designed to withstand acidic environments. In further embodiments, the sealing media is designed to withstand alkaline environments. In still further embodiments, the sealing media is designed to withstand oxidizing environments.

[0056] In embodiments concerning the casing and concerning the spool, the casing or tubing spool comprise strong rigid material. Examples of materials especially suited for casing and tubing spools include steel, stainless steel, aluminum, tungsten, brass, cobalt, iron, ceramics carbon fibers or a combination thereof. Certain embodiments of the invention pertain to the use of a casing spool. Other embodiments of the invention pertain to the use of a tubing spool.

[0057] Depicted in Fig. 1 is a typical wellhead 80. A tubing head spool 90 is distal to the wellhead support plate 100. [0058] Depicted in Fig. 2 is a casing spool 10, which in certain embodiments is composed of a metal such as steel. The casing spool further defines a central axis 15. Further, the casing spool 10 has a casing spool cavity 70 with an inward facing wall. The casing spool cavity 70 is adapted to receive a bushing 50.

[0059] Perpendicular to the central axis 15 of the casing spool 10, as depicted in Fig. 2, is a single injection port 20 embodied by the present invention for the injection of sealing media. As can be further seen in Fig. 2, the bushing 50 and the casing spool cavity 70 are near the proximal end of the casing spool 10. As such, the injection port 20 allows for the injection of sealing media around the bushing 50.

[0060] With more particularity regarding Fig. 2, the injection port 20 is fluidly connected to the annular grooves 60, which circumscribe the bushing 50. Upon entry into the sealing media passages 30, sealing media travels in an inward direction to the annular grooves 60. Still further, specifically, this port 20 is located in the flange region of the casing spool.

[0061] Regarding the sealing media passages 30 as depicted in Fig. 2, are the mechanical seals. The sealing media passages provide sealing media to the mechanical seals 40. As depicted in Fig. 2, the bushing has two mechanical seals 40, which comprise an elastomeric substance.

[0062] Further, the mechanical seals 40 circumscribe the bushing 50 and are perpendicular to the central axis 15.

[0063] Fig. 3 is a cross sectional illustration of the bushing 50. Further shown in Fig. 3 are the annular grooves 60 oriented perpendicular to the shaft axis 15. The annular grooves 60 are fluidly connected to the injection port by lateral passages 35. Upon entry into the sealing media passages 30, the bushing seals, or mechanical seals 40 are energized by the sealing media. Thereby eliminating multiple entry ports for injecting sealing media into a casing spool 10 or tubing spool.

[0064] From the foregoing description, one of ordinary skill in the art can easily ascertain the essential characteristics of this disclosure, and without departing from the spirit and scope thereof, can make various changes and modifications to adapt the disclosure to various usages and conditions. For example, we do not mean for references such as above, below, left, right, and the like to be limiting but rather as a guide for orientation of the referenced element to another element. A person of skill in the art should understand that certain of the above-described structures, functions, and operations of the above-described embodiments are not necessary to practice the present disclosure and are included in the description simply for completeness of an exemplary embodiment or embodiments. In addition, a person of skill in the art should understand that specific structures, functions, and operations set forth in the above-described referenced patents and publications can be practiced in conjunction with the present disclosure, but they are not essential to its practice.

[0065] The invention can be embodied in other specific forms without departing from its spirit or essential characteristics. A person of skill in the art should consider the described embodiments in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. A person of skill in the art should embrace, within their scope, all changes to the claims which come within the meaning and range of equivalency of the claims. Further, we hereby incorporate by reference, as if presented in their entirety, all published documents, patents, and applications mentioned herein.

Claims

1. A wellhead spool, the wellhead spool further comprising:

A. a wellhead spool casing having an inward facing wall having a distal end oriented away from a wellhead and a proximal end oriented toward a wellhead; the inward facing wall of the wellhead spool forming a wellhead spool cavity adapted to receive a bushing, the wellhead spool further defining a central axis;

B. a bushing having an outward facing wall and an inward facing wall, the inward facing wall defining a bushing bore, the bushing being positioned within the wellhead spool cavity;

C. an injection port traversing from an exterior of the wellhead spool to the wellhead spool cavity;

D. at least one mechanical seal within the bushing bore, the bushing bore circumscribing the at least one mechanical seal; and wherein sealing media is injected into the injection port and contacts the at least one mechanical seal.

2. The wellhead spool of claim 1, wherein the wellhead spool is a casing spool or a tubing spool.

3. The wellhead spool of claim 2, wherein the wellhead spool has at least one sealing media passage fluidly connecting the at least one mechanical seal to the injection port.

4. The wellhead spool of claim 3, wherein the bushing has a plurality of sealing media passages.

5. The wellhead spool of claim 3, wherein the at least one sealing media passage is parallel to the central axis.

6. The wellhead spool of claim 3, wherein the at least one mechanical seal abuts the at least one sealing media passage.

7. The wellhead spool of claim 3, wherein the bushing has at least one annular groove abutting the inner wall of the bushing.

8. The wellhead spool of claim 7, wherein the bushing has a plurality of annular grooves.

9. The wellhead spool of claim 7, wherein at least one the sealing media passage is in fluid connection with the at least one annular groove and wherein the injection port is in fluid connection with the at least one annular groove.

10. The wellhead spool of claim 1, wherein the at least one mechanical seal is an elastomeric mechanical seal.

11. The wellhead spool of claim 1, wherein the wellhead spool casing is stainless steel.

12. A method of sealing the wellhead spool of claim 9, comprising injecting a sealing media into the injection port.

13. The method of claim 12, wherein the sealing media flows into the at least one annular groove.

14. The method of claim 13, wherein the sealing media flows from the at least one sealing media passage into the at least one annular groove.

15. The method of claim 14, wherein the media contacts the at least one mechanical seal.

16. The method of claim 15, wherein the sealing media hardens upon flowing from the injection port to the at least one mechanical seal.

17. The method of claim 15, wherein the sealing media remains a liquid upon flowing from the injection port to the at least one mechanical seal.

18. The method of claim 12, wherein the sealing media comprises a fluoropolymer.