Sealing array for high temperature applications

A sealing array for positioning in an annular space between tubular members to provide a seal therebetween. The sealing array includes a pair of oppositely disposed backup rings, each defining a primary outer seal member of the sealing array. A pair of rigid cap rings is disposed between the backup rings. Each cap ring has a substantially planar surface and an oppositely disposed surface that engages one of the backup rings to energize the backup rings upon the application of sufficient pressure. The cap rings are sized to form controlled extrusion gaps with both tubular members. An energizing element is disposed between the planar surfaces of the cap rings. The energizing element engages a planar surface of at least one of the cap rings and seals the extrusion gaps associated with the engaged cap ring upon the application of sufficient pressure.

TECHNICAL FIELD OF THE INVENTION

This invention relates, in general, to an improved sealing system for use in high temperature applications and, in particular, to a sealing array that includes a configuration of an energizing element, cap rings and backup rings that provide for enhanced sealing in high temperature applications.

BACKGROUND OF THE INVENTION

Without limiting the scope of the present invention, its background is described with reference to sealing in high temperature steam applications, as an example.

It is well known in the oil and gas extraction art that an O-ring may be used to form an effective seal between two cylindrically shaped parts that cooperate in either a static or dynamic environment. Typically, one of the cooperating parts will include a gland groove in which the O-ring type seal is placed. In order to establish the desired seal between the two parts, the O-ring must be under contact stress with both parts during operations. According to one common practice, the O-ring gland groove is disposed on the inner cooperating part and has a diameter slightly larger than the inner diameter of the O-ring and wider than the cross section of the O-ring. This design provides the desired contact stress to the O-ring and allows axial movement of the O-ring as it is inserted into the sealing area.

It has been found, however, in certain high temperature installations, that the useful life of such a single O-ring in a gland groove is limited. This is due, in part, to the tendency of the elastomeric O-ring materials to extrude into the clearance gap between the cooperating parts. To overcome this deficiency, use of a packing stack or sealing array that includes a centrally disposed O-ring seal and one or more O-ring support members positioned on either side of the O-ring, has been attempted. The O-ring support members, which are also referred to as backup rings, commonly include V-rings, which are V-shaped or Chevron type packing rings with a concave, V-shaped bottom surface, a convex top surface and straight sides. According to this practice, the centrally disposed O-ring and the backup rings work together to provide the desired seal, with the aforementioned clearance gap being filled by the backup rings, thereby preventing O-ring extrusion.

It has been found, however, that in very high temperature applications, such as steam applications, the useful life of conventional sealing arrays is limited. For example, that material of the O-ring seals tends to diffuse into or become integrally bonded with the material of the adjacent V-ring seals, resulting in a loss of the round cross section of the O-ring seals. This loss of geometric integrity not only limits the sealing capability of the O-ring itself but also limits the O-ring's ability to energize the V-rings, thereby reducing or eliminating contact at the sealing boundaries.

Therefore, a need has arisen for a sealing array that provides the desired sealing functionality between cooperating parts. A need has also arisen for such a sealing array that is capable of maintaining the desired sealing functionality in high temperature applications. Further, a need has arisen for such a sealing array that is capable of maintaining the desired sealing functionality in very high temperature applications including steam applications.

SUMMARY OF THE INVENTION

The present invention disclosed herein comprises a sealing array that provides the desired sealing functionality between cooperating parts. The sealing array of the present invention is capable of maintaining the desired sealing functionality in high temperature applications. In addition, the sealing array of the present invention is capable of maintaining the desired sealing functionality in very high temperature applications including steam applications.

In one aspect, the present invention is directed to a sealing array for positioning in an annular space between tubular members to provide a seal therebetween. The sealing array includes a pair of oppositely disposed backup rings, each having a concave surface and each defining a primary outer seal member of the sealing array. A pair of rigid cap rings is disposed between the backup rings. Each of the cap rings has a convex surface and an oppositely disposed substantially planar surface. The convex surface of each of the cap rings engages a concave surface of one of the backup rings to energize the backup rings upon the application of sufficient pressure. The cap rings are sized to form extrusion gaps with both tubular members. An energizing element is disposed between the planar surfaces of the cap rings. The energizing element engages a planar surface of at least one of the cap rings and seals the extrusion gaps associated with the engaged cap ring upon the application of sufficient pressure.

In one embodiment, the backup rings may be V-rings. In another embodiment, the backup rings may have a chevron-shape. In a further embodiment, the backup rings may be formed from a material with a very low thermal expansion coefficient and high lubricity such as a flexible graphite or may be formed from a polymeric material including a thermoplastic, an elastomer, a fluoropolymer or the like.

In one embodiment, the caps rings may be D-rings. In another embodiment, the caps rings may be extended D-rings. In a further embodiment, the caps rings may be formed from a metal such as a stainless steel, a polymer such as a thermally resistant polymer, a rigid composite material or the like. In yet another embodiment, the energizing element may be an O-ring formed from a polymer and preferably an elastomer.

In one embodiment, one or more addition pairs of backup rings may be used. In this embodiment, each of the additional backup rings forms a secondary outer seal member having a concave surface engaging a convex surface of one of the primary outer seal members or one of the other secondary outer seal members. In another embodiment, a pair of adaptor members may be used. Each of the adaptor members has a concave surface engaging a convex surface of one of the primary outer seal members or one of the secondary outer seal members. In this embodiment, the adaptor members may be formed from a metal such as a stainless steel, a polymer such as a thermally resistant polymer, a rigid composite material or the like.

In another aspect, the present invention is directed to a sealing array for positioning in an annular space between tubular members to provide a seal therebetween. The sealing array includes a pair of oppositely disposed flexible graphite V-rings, each having a concave surface and each defining a primary outer seal member of the sealing array. A pair of stainless steel extended D-rings is positioned between the V-rings. Each of the D-rings has a convex surface and an oppositely disposed substantially planar surface. The convex surface of each of the D-rings engages a concave surface of one of the V-rings to energize the V-rings upon the application of sufficient pressure. The D-rings are sized to form extrusion gaps with both tubular members. An O-ring formed from a temperature resistant material such as ethylene propylene diene monomer is disposed between the planar surfaces of the D-rings. The O-ring engages a planar surface of at least one of the D-rings and seals the extrusion gaps associated with the engaged D-ring upon the application of sufficient pressure.

In a further aspect, the present invention is directed to a sealing array for positioning in an annular space between tubular members to provide a seal therebetween. The sealing array includes a pair of oppositely disposed backup rings, each defining a primary outer seal member of the sealing array. A pair of rigid cap rings is disposed between the backup rings. Each cap ring having a substantially planar surface and an oppositely disposed surface that engages one of the backup rings to energize the backup rings upon the application of sufficient pressure. The cap rings are sized to form extrusion gaps with both tubular members. An energizing element is disposed between the planar surfaces of the cap rings. The energizing element engages a planar surface of at least one of the cap rings and seals the extrusion gaps associated with the engaged cap ring upon the application of sufficient pressure.

In a yet another aspect, the present invention is directed to a sealing array for positioning in an annular space between tubular members to provide a seal therebetween. The sealing array includes a backup ring that defines a primary outer seal member of the sealing array, a rigid cap ring having a substantially planar surface and an oppositely disposed surface that engages a surface of the backup ring to energize the backup ring upon the application of sufficient pressure, the cap ring sized to form extrusion gaps with both tubular members and an energizing element operably engageable with the substantially planar surface of the cap ring to provide a seal in the extrusion gaps associated with the cap ring upon the application of sufficient pressure.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially toFIG. 1, therein is depicted a sealing array according to an embodiment of the present invention that is positioned between cooperating tubular members and is generally designated100. In the illustrated section of the tubing system, an outer tubular section102includes shoulder104. Operably associated with outer tubular section102is an outer tubular section106which may be threadably coupled to outer tubular section102or otherwise fixed relative thereto. Outer tubular section106includes an upper end portion108and an upper surface110. Upper end portion108of outer tubular section106is received within a radially reduced portion112of outer tubular section102. Together, shoulder104and radially reduced portion112of outer tubular section102and upper surface110of outer tubular section106form a gland groove for housing sealing array100. In one example, outer tubular section102and outer tubular section106are consecutively disposed tubular members in a downhole tubular string with sealing array100positioned to the interior of the downhole tubular string.

Disposed adjacent of outer tubular section102and outer tubular section106is a tubular member114. In the illustrated embodiment, tubular member114includes a shoulder116that interacts with no-go shoulder118of outer tubular section106. As an example, tubular member114may be one tool in a wireline conveyed tool system that is inserted into the tubular string including outer tubular section102and outer tubular section106. As illustrated, a clearance gap120exists between tubular member114and outer tubular section102, a clearance gap122exists between tubular member114and outer tubular section106, and a clearance gap124generally exists between tubular member114and sealing array100. Clearance gaps120,122,124allow for the insertion and removal of tubular member114from outer tubular section102and outer tubular section106with minimal resistance and without damage to sealing array100.

Sealing array100includes a pair of oppositely disposed adaptor members126,128. As illustrated in the cross sectional view ofFIG. 1, upper adaptor member126has a substantially planar surface130that is adjacent to shoulder104of outer tubular section102. Upper adaptor member126also has a substantially V-shaped lower surface132. Likewise, lower adaptor member128has a substantially planar surface134that is adjacent to upper surface110of outer tubular section106. Lower adaptor member128also has a substantially V-shaped upper surface136. Adaptor members126,128are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections102,106and between radially reduced portion112of outer tubular section102and tubular member114. Preferably, adaptor members126,128are formed from a rigid material including plastics, composites or metals. In high temperature applications including steam applications, adaptor members126,128are preferably formed from a stainless steel including corrosion resistant, 9-chrome, 13-chrome and nickel alloy stainless steels.

Sealing array100includes a pair of oppositely disposed backup rings138,140. As illustrated in the cross sectional view ofFIG. 1, upper backup ring138has a substantially arc shaped convex surface142that is adjacent to substantially V-shaped surface132of adaptor member126. Upper backup ring138also has a substantially arc shaped concave surface144with substantially planer outer segments146,148. Likewise, lower backup ring140has a substantially arc shaped convex surface150that is adjacent to substantially V-shaped surface136of adaptor member128. Lower backup ring140also has a substantially arc shaped concave surface152with substantially planer outer segments154,156. Backup rings138,140are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections102,106and between radially reduced portion112of outer tubular section102and tubular member114. Preferably, backup rings138,140are formed from a polymer such as a thermoplastic including polyetheretherketone (PEEK), an elastomer including ethylene propylene diene monomer (EPDM) or a fluoropolymer including polytetrafluoroethylene (PTFE). In certain high temperature applications including steam applications, backup rings138,140are preferably formed from a flexible graphite including Grafoil® and Grafoil® composites. It should be understood by those skilled in the art that other materials could alternatively be used to form backup rings138,140with the material being selected based upon factors such as chemical compatibility, application temperature, sealing pressure and the like.

Sealing array100includes a pair of oppositely disposed cap rings158,160depicted in the form of extended D-rings. As illustrated in the cross sectional view ofFIG. 1, upper cap ring158has a substantially arc shaped convex surface162with substantially planer outer segments164,166that nest with substantially arc shaped concave surface144and substantially planer outer segments146,148of backup ring138. Upper cap ring158also has a substantially planar surface168. Likewise, lower cap ring160has a substantially arc shaped convex surface170with substantially planer outer segments172,174that nest with substantially arc shaped concave surface152and substantially planer outer segments154,156of backup ring140. Lower cap ring160also has a substantially planar surface176. Cap rings158,160are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections102,106and between radially reduced portion112of outer tubular section102and tubular member114. Preferably, cap rings158,160are formed from a rigid material including plastics, composites or metals. In high temperature applications including steam applications, cap rings158,160are preferably formed from a stainless steel including corrosion resistant, 9-chrome, 13-chrome and nickel alloy stainless steels.

Sealing array100includes an energizing element depicted as O-ring seal178positioned between cap rings158,160. O-ring seal178is substantially ring shaped and is sized to fit in the cylindrical gland groove created between outer tubular sections102,106and between radially reduced portion112of outer tubular section102and tubular member114. Preferably, O-ring seal178is formed from an elastomer such as a synthetic rubber, a butadiene rubber (BR), a nitrile rubber (NBR), a fluoroelastomer (FKM), a perfluoroelastomer (FFKM) or other thermoset material. In high temperature applications including steam applications, O-ring seal178is preferably formed from an ethylene propylene diene monomer (EPDM). It should be understood by those skilled in the art that other materials could alternatively be used to form O-ring seal178with the material being selected based upon factors such as chemical compatibility, application temperature, sealing pressure and the like. In addition, even though the energizing element has been depicted as O-ring seal178, those skilled in the art should recognize that the energizing element could have a alternate configurations, including, but not limited to, quad rings, square block seals, beta seals and the like, which allow the energizing element to energize sealing array100when sufficient pressure is applied thereto and which allow the energizing element to engage in controlled wedging into the extrusion gaps as described below.

Even thoughFIG. 1depicts the sealing array of the present invention in a vertical orientation, it should be understood by those skilled in the art that the sealing arrays of the present invention are equally well suited for use in other directional orientations including horizontal and slanted orientations. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure.

The operation of sealing array100will now be described with reference toFIG. 2. Sealing array100is a bidirectional sealing array. Specifically, sealing array100is designed to prevent pressure from escaping from the region above clearance gap120into the region below clearance gap122when the pressure in the region above clearance gap120is higher than the pressure in the region below clearance gap122. Likewise, sealing array100is designed to prevent pressure from escaping from the region below clearance gap122into the region above clearance gap120when the pressure in the region below clearance gap122is higher than the pressure in the region above clearance gap120. In the embodiment illustrated inFIG. 2, the pressure in the region below clearance gap122is higher than the pressure in the region above clearance gap120. Accordingly, the upper portion of sealing array100has been energized and is providing a seal that prevents pressure from escaping from the region below clearance gap into the region above clearance gap120.

As illustrated, the pressure has caused O-ring to become compressed against surface168of cap ring158. The force acting on cap ring158presses cap ring158into backup ring138and likewise presses backup ring138into adaptor member126. The interaction between surface162of cap ring158and surface144of backup ring138as well as the interaction between surface132of adaptor member126and surface142of backup ring138causes backup ring to be energized resulting in longitudinal compression and radial expansion of backup ring138. The energized backup ring138establishes a seal against the inner surface of radially reduced portion112of outer tubular section102and the outer surface of tubular member114. The seal created by energized backup ring138is referred to herein as a primary outer seal.

In addition to applying the upwardly directed force on backup ring138, cap ring158is substantially centered between the inner surface of radially reduced portion112of outer tubular section102and the outer surface of tubular member114, thereby forming narrow extrusion gaps180,182therebetween. Under sufficient pressure, as depicted inFIG. 2, O-ring178extrudes into extrusion gaps180,182as illustrated at184and186. Accordingly, the configuration of seal array100allows a desirable amount of O-ring extrusion to assure a complete seal but prevents excessive O-ring extrusion through the use of backup ring138which establishes a barrier to additional O-ring extrusion at146,148when backup ring138is energized. The extent of the O-ring extrusion may be determined by the length of the extended portion of cap ring158when cap ring158has the extended D-ring shape, as depicted.

In addition to applying the upwardly directed force to energize backup ring138and establishing the extrusion gaps to assure a complete seal, cap ring158provides a barrier between O-ring178and backup ring138which prevents physical and chemical interaction therebetween. Specifically, the barrier created by cap ring158prevents the aforementioned loss of geometric integrity that occurs when the material of an O-ring chemically interacts with the material of a backup ring. Accordingly, as cap ring158prevents chemical and physical interaction between O-ring178and backup ring138during operation, the useful life of sealing array100is extended.

Referring now toFIG. 3, therein is depicted a sealing array according to an embodiment of the present invention that is positioned between cooperating tubular members and is generally designated200. A tubing system includes outer tubular section202with shoulder204and outer tubular section206with upper end portion208and upper surface210which is received within a radially reduced portion212of outer tubular section202. Together, shoulder204and radially reduced portion212of outer tubular section202and upper surface210of outer tubular section206form a gland groove for housing sealing array200. Disposed adjacent to outer tubular section202and outer tubular section206is a tubular member214that includes a shoulder216that interacts with no-go shoulder218of outer tubular section206. As illustrated, a clearance gap220exists between tubular member214and outer tubular section202, a clearance gap222exists between tubular member214and outer tubular section206, and a clearance gap224generally exists between tubular member214and sealing array200.

Sealing array200includes a pair of oppositely disposed adaptor members226,228. As illustrated in the cross sectional view ofFIG. 3, upper adaptor member226has a substantially planar surface230that is adjacent to shoulder204of outer tubular section202. Upper adaptor member226also has a substantially V-shaped lower surface232. Likewise, lower adaptor member228has a substantially planar surface234that is adjacent to upper surface210of outer tubular section206. Lower adaptor member228also has a substantially V-shaped upper surface236. Adaptor members226,228are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections202,206and between radially reduced portion212of outer tubular section202and tubular member214.

Sealing array200includes a pair of oppositely disposed backup rings238,240. As illustrated in the cross sectional view ofFIG. 3, upper backup ring238has a substantially arc shaped convex surface242that is adjacent to substantially V-shaped surface232of adaptor member226. Upper backup ring238also has a substantially arc shaped concave surface244with substantially planer outer segments246,248. Likewise, lower backup ring240has a substantially arc shaped convex surface250that is adjacent to substantially V-shaped surface236of adaptor member228. Lower backup ring240also has a substantially arc shaped concave surface252with substantially planer outer segments254,256. Backup rings238,240are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections202,206and between radially reduced portion212of outer tubular section202and tubular member214.

Sealing array200includes a pair of oppositely disposed cap rings258,260depicted in the form of D-rings. As illustrated in the cross sectional view ofFIG. 3, upper cap ring258has a substantially arc shaped convex surface262that nests with substantially arc shaped concave surface244of backup ring238. Upper cap ring258also has a substantially planar surface268. Likewise, lower cap ring260has a substantially arc shaped convex surface270that nests with substantially arc shaped concave surface252of backup ring240. Lower cap ring260also has a substantially planar surface276. Cap rings258,260are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections202,206and between radially reduced portion212of outer tubular section102and tubular member214. In addition, sealing array200includes an O-ring seal278positioned between cap rings258,260. O-ring seal278is substantially ring shaped and is sized to fit in the cylindrical gland groove created between outer tubular sections202,206and between radially reduced portion212of outer tubular section202and tubular member214.

The operation of sealing array200will now be described with reference toFIG. 4. As with sealing array100, sealing array200is a bidirectional sealing array. In the illustrated embodiment, the pressure in the region below clearance gap222is higher than the pressure in the region above clearance gap220. Accordingly, the upper portion of sealing array200has been energized and is providing a seal that prevents pressure from escaping from the region below clearance gap222into the region above clearance gap220.

As illustrated, the pressure has caused O-ring278to become compressed against surface268of cap ring258. The force acting on cap ring258presses cap ring258into backup ring238and likewise presses backup ring238into adaptor member226. The interaction between surface262of cap ring258and surface244of backup ring238as well as the interaction between surface232of adaptor member226and surface242of backup ring238causes backup ring to be energized resulting in longitudinal compression and radial expansion of backup ring238. The energized backup ring238establishes a seal against the inner surface of radially reduced portion212of outer tubular section202and the outer surface of tubular member214.

In addition to applying the upwardly directed force on backup ring238, cap ring258is substantially centered between the inner surface of radially reduced portion212of outer tubular section202and the outer surface of tubular member214, thereby forming narrow extrusion gaps280,282therebetween. Under sufficient pressure, as depicted inFIG. 4, O-ring278extrudes into the extrusion gaps. Accordingly, the configuration of seal array200allows a desirable amount of O-ring extrusion to assure a complete seal but, prevents excessive O-ring extrusion through the use of backup ring238which establishes a barrier to additional O-ring extrusion at246,248when backup ring238is energized.

In addition to applying the upwardly directed force to energize backup ring238and establishing the extrusion gaps to assure a complete seal, cap ring258provides a barrier between O-ring278and backup ring238which prevents physical and chemical interaction therebetween.

Referring now toFIG. 5, therein is depicted a sealing array according to an embodiment of the present invention that is positioned between cooperating tubular members and is generally designated300. A tubing system includes outer tubular section302with shoulder304and outer tubular section306with upper end portion308and upper surface310which is received within a radially reduced portion312of outer tubular section302. Together, shoulder304and radially reduced portion312of outer tubular section302and upper surface310of outer tubular section306form a gland groove for housing sealing array300. Disposed adjacent to outer tubular section302and outer tubular section306is a tubular member314that includes a shoulder316that interacts with no-go shoulder318of outer tubular section306. As illustrated, a clearance gap320exists between tubular member314and outer tubular section302, a clearance gap322exists between tubular member314and outer tubular section306, and a clearance gap324generally exists between tubular member314and sealing array300.

Sealing array300includes a pair of oppositely disposed adaptor members326,328. As illustrated in the cross sectional view ofFIG. 5, upper adaptor member326has a substantially planar surface330that is adjacent to shoulder304of outer tubular section302. Upper adaptor member326also has a substantially V-shaped lower surface332. Likewise, lower adaptor member328has a substantially planar surface334that is adjacent to upper surface310of outer tubular section306. Lower adaptor member328also has a substantially V-shaped upper surface336. Adaptor members326,328are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections302,306and between radially reduced portion312of outer tubular section302and tubular member314.

Sealing array300includes a pair of oppositely disposed backup rings338,340. As illustrated in the cross sectional view ofFIG. 5, upper backup ring338has a substantially arc shaped convex surface342that is adjacent to substantially V-shaped surface332of adaptor member326. Upper backup ring338also has a substantially planar surface344. Likewise, lower backup ring340has a substantially arc shaped convex surface350that is adjacent to substantially V-shaped surface336of adaptor member328. Lower backup ring340also has a substantially planar surface352. Backup rings338,340are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections302,306and between radially reduced portion312of outer tubular section302and tubular member314.

Sealing array300includes a pair of oppositely disposed cap rings358,360. As illustrated in the cross sectional view ofFIG. 5, upper cap ring358has a substantially planar surface362that engages with substantially planar surface344of backup ring338. Upper cap ring358also has a substantially planar surface368. Likewise, lower cap ring360has a substantially planar surface270that engages with substantially planar surface352of backup ring340. Lower cap ring360also has a substantially planar surface376. Cap rings358,360are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections302,306and between radially reduced portion312of outer tubular section302and tubular member314. In addition, sealing array300includes an O-ring seal378positioned between cap rings358,360. O-ring seal378is substantially ring shaped and is sized to fit in the cylindrical gland groove created between outer tubular sections302,306and between radially reduced portion312of outer tubular section302and tubular member314.

The operation of sealing array300will now be described with reference toFIG. 6. As with sealing array100, sealing array300is a bidirectional sealing array. In the illustrated embodiment, the pressure in the region below clearance gap322is higher than the pressure in the region above clearance gap320. Accordingly, the upper portion of sealing array300has been energized and is providing a seal that prevents pressure from escaping from the region below clearance gap322into the region above clearance gap320.

As illustrated, the pressure has caused O-ring378to become compressed against surface368of cap ring358. The force acting on cap ring358presses cap ring358into backup ring338and likewise presses backup ring338into adaptor member326. The interaction between surface362of cap ring358and surface344of backup ring338as well as the interaction between surface332of adaptor member326and surface342of backup ring338causes backup ring to be energized resulting in longitudinal compression and radial expansion of backup ring338. The energized backup ring338establishes a seal against the inner surface of radially reduced portion312of outer tubular section302and the outer surface of tubular member314.

In addition to applying the upwardly directed force on backup ring338, cap ring358is substantially centered between the inner surface of radially reduced portion312of outer tubular section302and the outer surface of tubular member314, thereby forming narrow extrusion gaps380,382therebetween. Under sufficient pressure, as depicted inFIG. 6, O-ring378extrudes into the extrusion gaps as illustrated at384and386. Accordingly, the configuration of seal array300allows a desirable amount of O-ring extrusion to assure a complete seal but prevents excessive O-ring extrusion through the use of backup ring338which establishes a barrier to additional O-ring extrusion when backup ring338is energized. The extent of the O-ring extrusion may be determined by the length of cap ring358.

In addition to applying the upwardly directed force to energize backup ring338and establishing the extrusion gaps to assure a complete seal, cap ring358provides a barrier between O-ring378and backup ring338which prevents physical and chemical interaction therebetween.

Referring now toFIG. 7, therein is depicted a sealing array according to an embodiment of the present invention that is positioned between cooperating tubular members and is generally designated400. A tubing system includes outer tubular section402with shoulder404and outer tubular section406with upper end portion408and upper surface410which is received within a radially reduced portion412of outer tubular section402. Together, shoulder404and radially reduced portion412of outer tubular section402and upper surface410of outer tubular section406form a gland groove for housing sealing array400. Disposed adjacent to outer tubular section402and outer tubular section406is a tubular member414that includes a shoulder416that interacts with no-go shoulder418of outer tubular section406. As illustrated, a clearance gap420exists between tubular member414and outer tubular section402, a clearance gap422exists between tubular member414and outer tubular section406, and a clearance gap424generally exists between tubular member414and sealing array400.

Sealing array400includes a pair of oppositely disposed adaptor members426,428. As illustrated in the cross sectional view ofFIG. 7, upper adaptor member426has a substantially planar surface430that is adjacent to shoulder404of outer tubular section402. Upper adaptor member426also has a substantially V-shaped lower surface432. Likewise, lower adaptor member428has a substantially planar surface434that is adjacent to upper surface410of outer tubular section406. Lower adaptor member428also has a substantially V-shaped upper surface436. Adaptor members426,428are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections402,406and between radially reduced portion412of outer tubular section402and tubular member414.

Sealing array400includes a pair of oppositely disposed backup rings438,440. As illustrated in the cross sectional view ofFIG. 7, first upper backup ring438has a substantially arc shaped convex surface442that is adjacent to substantially V-shaped surface432of adaptor member426. First upper backup ring438also has a substantially arc shaped concave surface444. Likewise, first lower backup ring440has a substantially arc shaped convex surface450that is adjacent to substantially V-shaped surface436of adaptor member428. First lower backup ring440also has a substantially arc shaped concave surface452. Backup rings438,440are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections402,406and between radially reduced portion412of outer tubular section402and tubular member414.

Sealing array400includes a second pair of oppositely disposed backup rings439,441. As illustrated in the cross sectional view ofFIG. 7, second upper backup ring439has a substantially arc shaped convex surface443that is adjacent to surface444of first upper backup ring438. Second upper backup ring439also has a substantially arc shaped concave surface445with substantially planer outer segments246,248. Likewise, second lower backup ring441has a substantially arc shaped convex surface451that is adjacent to surface452of first lower backup ring440. Second lower backup ring441also has a substantially arc shaped concave surface453with substantially planer outer segments454,456. Backup rings439,441are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections402,406and between radially reduced portion412of outer tubular section402and tubular member414.

Sealing array400includes a pair of oppositely disposed cap rings458,460depicted in the form of extended D-rings. As illustrated in the cross sectional view ofFIG. 7, upper cap ring458has a substantially arc shaped convex surface462with substantially planer outer segments464,466that nest with substantially arc shaped concave surface445and substantially planer outer segments446,448of backup ring439. Upper cap ring458also has a substantially planar surface468. Likewise, lower cap ring460has a substantially arc shaped convex surface470with substantially planer outer segments472,474that nest with substantially arc shaped concave surface453and substantially planer outer segments454,456of backup ring441. Lower cap ring460also has a substantially planar surface476. Cap rings458,460are both substantially ring shaped and are sized to fit in the cylindrical gland groove created between outer tubular sections402,406and between radially reduced portion412of outer tubular section402and tubular member414. In addition, sealing array400includes an O-ring seal478positioned between cap rings458,460. O-ring seal478is substantially ring shaped and is sized to fit in the cylindrical gland groove created between outer tubular sections402,406and between radially reduced portion412of outer tubular section402and tubular member414.

The operation of sealing array400will now be described with reference toFIG. 8. As with sealing array100, sealing array400is a bidirectional sealing array. In the illustrated embodiment, the pressure in the region below clearance gap422is higher than the pressure in the region above clearance gap420. Accordingly, the upper portion of sealing array400has been energized and is providing a seal that prevents pressure from escaping from the region below clearance gap422into the region above clearance gap420.

As illustrated, the pressure has caused O-ring478to become compressed against surface468of cap ring458. The force acting on cap ring458presses cap ring458into backup ring439, presses backup ring439into backup ring438and presses backup ring438into adaptor member426. The interaction between surface462of cap ring458and surface445of backup ring439as well as the interaction between surface432of adaptor member426and surface442of backup ring438causes both backup rings to be energized resulting in longitudinal compression and radial expansion of backup rings438,439. The energized backup rings438,439establish seals against the inner surface of radially reduced portion412of outer tubular section402and the outer surface of tubular member414. The seal created by energized backup ring439is referred to herein as a primary outer seal while seal created by energized backup ring438is referred to herein as a secondary outer seal.

In addition to applying the upwardly directed force on backup ring439, cap ring458is substantially centered between the inner surface of radially reduced portion412of outer tubular section402and the outer surface of tubular member414, thereby forming narrow extrusion gaps480,482therebetween. Under sufficient pressure, as depicted inFIG. 8, O-ring478extrudes into the extrusion gaps as illustrated at484and486. Accordingly, the configuration of seal array400allows a desirable amount of O-ring extrusion to assure a complete seal but prevents excessive O-ring extrusion through the use of backup ring439which establishes a barrier to additional O-ring extrusion at446,448when backup ring439is energized. The extent of the O-ring extrusion may be determined by the length of the extended portion of cap ring458when cap ring458has the extended D-ring shape as depicted.

In addition to applying the upwardly directed force to energize backup ring438and establishing the extrusion gaps to assure a complete seal, cap ring458provides a barrier between O-ring478and backup ring439which prevents physical and chemical interaction therebetween.

Even though a single pair of backup rings has been depicted inFIGS. 1-6and two pairs of backup rings have been depicted inFIGS. 7-8, it should be understood by those skilled in the art that the sealing arrays of the present invention may including any number of backup rings as desired and the material of such backup rings will be selected based upon the desired sealing performance in the proposed application. In addition, it should be understood by those skilled in the art that additional spacer members may be used with the sealing arrays of the present invention to fill the width of a gland groove. Typically, such spacer members will be disposed between one or both of the adaptor members and the adjacent tubular surface.