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Número de publicaciónWO2015156819 A1
Tipo de publicaciónSolicitud
Número de solicitudPCT/US2014/033826
Fecha de publicación15 Oct 2015
Fecha de presentación11 Abr 2014
Fecha de prioridad11 Abr 2014
Número de publicaciónPCT/2014/33826, PCT/US/14/033826, PCT/US/14/33826, PCT/US/2014/033826, PCT/US/2014/33826, PCT/US14/033826, PCT/US14/33826, PCT/US14033826, PCT/US1433826, PCT/US2014/033826, PCT/US2014/33826, PCT/US2014033826, PCT/US201433826, WO 2015/156819 A1, WO 2015156819 A1, WO 2015156819A1, WO-A1-2015156819, WO2015/156819A1, WO2015156819 A1, WO2015156819A1
InventoresTravis Raymond BURKE, Steven Daniel SOUTHWELL
SolicitanteSchlumberger Canada Limited, Services Petroliers Schlumberger, Schlumberger Holdings Limited, Schlumberger Technology B.V., Prad Research And Development Limited, Schlumberger Technology Corporation
Exportar citaBiBTeX, EndNote, RefMan
Enlaces externos:  Patentscope, Espacenet
Running string system
WO 2015156819 A1
Resumen
A technique facilitates operation of a running string of the type used to run and set a liner hanger system in a wellbore. The running string comprises a pressure equalizer sub. The pressure equalizer sub is constructed to equalize pressure between an exterior and an interior of the running string. The exterior of the running string may be the annulus between the running string and a liner or liner component of the liner hanger system. The pressure equalizer sub has components and features constructed and arranged to provide a simple and dependable technique for pressure equalization. Additionally, the pressure equalizer sub enables pressure equalization in a passive manner that does not involve operator action.
Reclamaciones  (El texto procesado por OCR puede contener errores)
CLAIMS What is claimed is:
1. A system for use in a well, comprising:
a running string having: a liner wiper plug positioned to wipe along an interior of a liner; and a pressure equalizer sub to equalize pressure between an exterior and an interior of the running string, the pressure equalizer sub comprising:
an external body having a pressure port therethrough;
an internal body disposed within the external body and having a flow port;
a piston slidably mounted between the external body and the internal body, the piston having a base portion and a piston stop portion extending in a radial direction from the base portion;
a check seal engaging the piston; and
a spring member positioned to bias the piston and the check seal toward a closed position blocking flow through the pressure port and the flow port, the piston moving against the spring to allow flow and pressure equalization through the pressure port and the flow port when a sufficient pressure differential is established between the exterior and the interior of the running string, the movement against the spring member being limited by engagement of the piston stop portion with a travel stop.
2. The system as recited in claim 1, wherein the pressure equalizer sub further comprises an outer seal disposed between the piston and the external body and an inner seal disposed between the piston and the internal body.
3. The system as recited in claim 2, wherein the piston comprises a piston flow port located between the outer seal and the check seal.
4. The system as recited in claim 3, wherein the piston flow port is elongated along a first direction and the flow port of the internal body is elongated in a second direction, the second direction being generally transverse to the first direction.
5. The system as recited in claim 1, wherein the movement against the spring
comprises initial movement for a predetermined distance prior to gradually increasing a flow area from the pressure port of the external body through the flow port of the internal body.
6. The system as recited in claim 1, wherein the pressure equalizer sub comprises a flow chamber downstream of the pressure port and located in a flow path from the pressure port of the external body to the flow port of the internal body, the flow chamber providing a region of relatively increased volume along the flow path.
7. The system as recited in claim 1, wherein the internal body comprises a plurality of pressure relief flow channels.
8. The system as recited in claim 1 , wherein the external body is coupled with a collet oriented to releasably engage the liner wiper plug.
9. The system as recited in claim 1, wherein the sufficient pressure differential comprises a pressure differential of about 60-70 psi (413-483 kPa).
10. The system as recited in claim 1, wherein the spring member comprises a coil spring and the piston comprises an annular piston.
11. The system as recited in claim 1 , wherein the piston comprises a leading nose having an angled surface oriented to incrementally increase flow area as the piston is transitioned against the spring member to a full open position.
12. The system as recited in claim 1, further comprising a liner hanger system having a liner top packer and a liner hanger, the running string extending into an interior of the liner hanger system.
13. A method for use in a well, comprising: positioning a running string in a liner hanger system;
running the running string and the liner hanger system downhole into a wellbore;
using a pressure equalizer sub in the running string to help equalize pressure between an annulus around the running string and an interior of the running string by utilizing a piston movable from a closed position to an open position until further movement is blocked by a travel stop;
biasing the piston toward the closed position with a spring selected to establish a pressure differential level for shifting the piston to the open position; and
stabilizing movement of the piston with an arrangement of ports between the annulus and the interior of the running string.
14. The method as recited in claim 13, further comprising forming the piston with a piston base portion and a piston stop portion extending radially outwardly from the piston base portion for engagement with the travel stop.
15. The method as recited in claim 13, further comprising slidably mounting the piston between an external body having a pressure port and an internal body having a flow port so that sufficient movement of the piston enables the pressure equalization through the pressure port and the flow port.
16. The method as recited in claim 15, wherein stabilizing comprises forming the flow port as an elongated port oriented in a longitudinal direction and further comprises controlling flow to the flow port via an elongated piston flow port in the piston, the elongated piston flow port being oriented in a transverse direction.
17. The method as recited in claim 16, wherein stabilizing comprises moving the piston over a predetermined distance toward the open position before allowing the pressure port to fluidly communicate with the flow port; and once the pressure port and flow port are in communication, directing fluid flow through an expanded volume flow chamber between the pressure port and the flow port.
18. The method as recited in claim 13, wherein biasing comprises holding the piston in the closed position until at least a 60 psi (413 kPa) pressure differential is established between the annulus and the interior.
19. A system, comprising : a pressure equalizer sub comprising:
an external body having a pressure port;
an internal body having a flow port;
a piston slidably mounted between the external body and the internal body, the piston having a piston flow port;
a check seal engaging the piston; and
a spring member positioned to bias the piston and the check seal toward a closed position blocking flow through the pressure port and the flow port, the piston moving against the spring to allow flow and pressure equalization through the pressure port and the flow port when a sufficient pressure differential is established between the exterior and the interior of the running string, the pressure port, piston flow port, and flow port being arranged to provide a gradual increase in flow area as the piston is transitioned from a closed position to an open position, the pressure equalizer sub enabling pressure equalization in a passive manner that does not involve operator action. The system as recited in claim 19, wherein the sufficient pressure differential comprises a pressure differential of about 60-70 psi (413-483 kPa).
Descripción  (El texto procesado por OCR puede contener errores)

RUNNING STRING SYSTEM

BACKGROUND

[0001] A liner hanger system comprises a liner hanger which is used to hang a liner within host casing. A liner comprises a tubular, e.g. a casing, which joins the host casing at a downhole location. A running string is employed to run the liner hanger system downhole into a wellbore before being disengaged to leave the liner hanger and liner at a desired location along the wellbore. The running string may then be withdrawn from the wellbore. Depending on the specifics of the application and environment, the liner hanger system and the running string may comprise a variety of systems and components.

SUMMARY

[0002] In general, a methodology and system are provided to facilitate operation of a running string of the type used to run and set a liner hanger system in a wellbore. The running string may comprise a pressure equalizer sub. The pressure equalizer sub is constructed to equalize pressure between the exterior and the interior of the running string. The exterior of the running string may be the annulus between the running string and a liner or liner component of the liner hanger system. The pressure equalizer sub has components and features which enable a simple and dependable technique for pressure equalization. Additionally, the pressure equalizer sub enables pressure equalization in a passive manner that does not involve operator action.

[0003] However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:

[0005] Figure 1 is an illustration of an example of a liner hanger system, according to an embodiment of the disclosure;

[0006] Figure 2 is an illustration of an example of a running string that may be used within the liner hanger system illustrated in Figure 1 , according to an embodiment of the disclosure;

[0007] Figure 3 is a cross-sectional view of an example of a pressure equalizer sub of the running string, according to an embodiment of the disclosure;

[0008] Figure 4 is a cross-sectional view of a portion of the pressure equalizer sub illustrated in Figure 3, according to an embodiment of the disclosure;

[0009] Figure 5 is a cross-sectional view similar to that of Figure 4 but showing the pressure equalizer sub in a different operational position, according to an embodiment of the disclosure;

[0010] Figure 6 is an orthogonal view of an example of a valve piston which can be used in the pressure equalizer sub, according to an embodiment of the disclosure; and

[0011] Figure 7 is an orthogonal view of an internal body component of the pressure equalizer sub, according to an embodiment of the disclosure. DETAILED DESCRIPTION

[0012] In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

[0013] The present disclosure generally relates to a system and methodology to facilitate operation of a running string. In embodiments described herein, the running string may be used to run and set a liner hanger system in a wellbore. The running string also may comprise several types of components depending on the environment and application. For example, the running string comprises a pressure equalizer sub positioned and constructed to equalize pressure between the exterior and the interior of the running string. The exterior of the running string may be the annulus between the running string and a liner or liner component of the liner hanger system. The pressure equalizer sub has components and features which enable a simple and dependable technique for pressure equalization. Additionally, the pressure equalizer sub enables pressure equalization in a passive manner that does not involve operator action.

[0014] According to an embodiment, the pressure equalizer sub provides pressure equalization between annular pressure and the interior of the running string at a given pressure delta. The annular pressure may be an annulus between the liner and a running tool of the running string. A one way check valve assembly is used in the pressure equalizer sub to enable the pressure equalization in one direction. By way of example, the one way check valve assembly may utilize a piston, e.g. an annular piston, slidably mounted in the pressure equalizer sub to control flow between high and low pressure regions. [0015] The check feature is constructed to allow the check valve to remain closed in the pressure equalizer sub while internal running tool (ID) pressure exceeds the tool external or outside (OD) pressure. However, as the external (OD) pressure increases to a given range above the internal (ID) pressure, an internal piston is shifted. The piston shifts to allow flow ports to be exposed so pressure from the outside of the running tool can discharge into the interior of the running tool to enable desired pressure equalization between the OD and ID pressures. The pressure equalizer sub incorporates various features to facilitate equalization of pressure between the annulus pressure (OD) and the interior pressure (ID). Examples of these features include a check seal function, an ability to gradually increase flow area with piston travel, and use of a porting chamber or flow chamber. Additional features may comprise a unique porting construction for flow optimization and a piston stop feature which sets a range of piston motion. Examples of these features are discussed in greater detail below.

[0016] Referring generally to Figure 1, an embodiment of a liner hanger system

20 is illustrated. The liner hanger system 20 may comprise a variety of components and features depending on the parameters of a given application and environment. By way of example, the liner hanger system 20 may comprise a liner top packer 22 which works in cooperation with a liner hanger 24 to hang a liner 26 in a wellbore. The liner hanger system 20 also may comprise a landing collar 28 and additional features, such as a float collar 30 and a float shoe 32.

[0017] The liner hanger system 20 may be run downhole into a wellbore 34 via a running string 36, an example of which is illustrated in Figure 2. The running string 36 is releasably coupled with the liner hanger system 20 to facilitate deployment, setting, and operation of liner hanger system 20 before being retrieved to the surface. Once the liner hanger system 20 is set at a desired location in the wellbore 34, the running string 36 is released and the liner top packer 22, liner hanger 24 and liner 26 remain downhole in the wellbore 34. Depending on the parameters of a given application and environment, the running string 36 also may comprise a variety of components and features. [0018] In the illustrated example, the running string 36 comprises a liner wiper plug 38 and a pressure equalizer sub 40. The liner wiper plug 38 is used to clean an inside diameter of the liner 26 after hanging the liner 26, releasing the running string 36, and cementing an annulus between the liner 26 and wellbore 34. In some applications, the liner wiper plug can be run in hole at the bottom of the liner hanger system running string 36 and may be actuated hydraulically so as to release the liner wiper plug 38 from the remainder of the running string 36. Liner wiper plug 38 also may be used in combination with an additional plug or plugs, such as a follower wiper plug deployed independently at a sequential operational stage. The pressure equalizer sub 40 is employed to equalize pressure between an exterior and an interior of the running string 36, as described in greater detail below.

[0019] As illustrated, the running string 36 also may comprise a variety of additional components, such as a swab cup assembly 42 and a rotational ball seat sub 44 connected along the running string 36 in combination with a slick joint 45 and a retrievable cement bushing 46. The running string 36 also may comprise a running tool 48 positioned uphole of the retrievable cement bushing 46. In this example, the running tool 48 is used to releasably engage the liner hanger system 20. In the illustrated embodiment, the running string 36 also comprises a rotating dog sub 50 and a junk bonnet 52 positioned sequentially above the running tool 48. The illustrated components are examples of a variety of components that may be used in running string 36.

[0020] During a cementing operation, the running string 36 also may be used in cooperation with a setting ball 54 which is dropped down through an interior of the running string 36 into engagement with a ball seat in the ball seat sub 44. The setting ball 54 may be used to temporarily close off the longitudinal interior passage through the running string 36 to allow pressure to build inside the running string 36 for facilitating setting and deployment operations. A pump down plug 56 also may be used to facilitate the cementing operation by enabling application of pressure against the cement to force the cement into the desired regions of the wellbore annulus. [0021] According to a procedural example, the liner hanger system 20 is run downhole into the wellbore 34 via running tool string 36 and the liner hanger 24 is set, thus fixing liner 26 in position in wellbore 34. The running string 36 is then released from, for example, the inside diameter of the packer 22. Subsequently, the running string 36 may be raised to ensure that running tool 48 and the overall running string 36 have been properly disengaged. The retrievable cement bushing 46 is located inside packer 22 below an engagement feature of running tool 48 and serves as an isolation barrier.

[0022] The retrievable cement bushing 46 and the component arrangement of running string 36 can create a column of trapped fluid present in an annulus along the exterior of the running string 36 between the liner hanger system 20 and the running string 36. This column of trapped fluid is compressed between the retrievable cement bushing 46 and the liner wiper plug 38. By way of example, the liner wiper plug 38 may trap this column of fluid via seal fins or other sealing components 58. When the running string is picked up, e.g. raised, hydraulic pressure is applied to the liner wiper plug seal fins 58 (or other sealing components) and this hydraulic pressure can potentially be damaging. In the present embodiment, however, the pressure equalizer sub 40 relieves this buildup of pressure.

[0023] The pressure equalizer sub 40 is constructed to discharge this annular pressure along the exterior of the running string 36 into an interior of the running string upon a given delta pressure, i.e. a given pressure differential, while maintaining the internal pressure integrity of the running string 36 during setting operations. The pressure equalizer sub 40 is utilized and run in hole as part of the running string 36 and may be used in several different running string configurations. For example, the pressure equalizer sub 40 may be placed along running string 36 below the swab cup assembly 42 and/or below the slick joint 45 depending on the configuration of liner hanger system 20 and running string 36.

[0024] Referring generally to Figure 3, an example of pressure equalizer sub 40 is illustrated. The pressure equalizer sub 40 is constructed to provide pressure equalization between an exterior 60 and an interior 62 of the running string 36. This pressure equalization functionality enables release of pressure from, for example, the annulus created between the liner hanger system 20 and the running tool 48 before damaging seals 58 of liner wiper plug 38. The pressure equalizer sub 40 may utilize a one-way check valve type assembly 64 which actuates and relieves pressure upon the buildup of a predetermined pressure differential. The check feature effectively allows a valve to remain closed while internal tool pressure at the interior 62 exceeds the external pressure along the exterior 60. As the external pressure increases to a given range above the internal pressure, however, the pressure differential causes an internal piston 66 to transition or shift to provide a flow path between exterior 60 and interior 62.

[0025] The flow path allows pressure from the exterior 60 to discharge into the interior 62 of the running string 36 until the internal pressure rises and equalizes with the external pressure. In this context, equalizing of pressures refers to adjusting the relative levels of external pressure and internal pressure to a desired ratio or relationship. In some applications, equalizing the external pressure and the internal pressure may not involve creating the same internal and external pressure. For example, when equalizing external and internal pressures, the piston 66 may be shifted to a closed position prior to reaching an internal pressure that is the same pressure as the external pressure.

[0026] In the example illustrated, the piston 66 is slidably positioned between an external body 68 and an internal body 70 of pressure equalizer sub 40. By way of example, the piston 66 may be an annular piston slidably positioned around the internal body 70. The external body 68 has a pressure port 72 extending therethrough between an exterior and an interior of the external body 68. By way of example, the pressure port 72 may comprise a plurality of radial pressure ports 72. The internal body 70 is disposed within the external body 68 and has a flow port 74 extending therethrough between an exterior and an interior of the internal body 70. The flow port 74 similarly may comprise a plurality of radial flow ports 74. The flow port or ports 74 provide a flow path to interior 62 which is in the form of an internal longitudinal passage of the running string 36 extending through the pressure equalizer sub 40 and the overall running string 36. [0027] The external body 68 and internal body 70 may each be tubular in shape, and piston 66 may be slidably mounted at a radial position between external body 68 and internal body 70. In this example, the pressure equalizer sub 40 further comprises a spring 76 and a setting adapter 78. The spring 76 is positioned radially between external body 68 and internal body 70 and longitudinally between the piston 66 and a shoulder 80 of setting adapter 78. In this position, spring 76 is able to act against piston 66 and to bias piston 66 toward a closed position. Spring 76 also may be used to establish the level of pressure differential between exterior 60 and interior 62 which will cause movement of piston 66 from the closed position to an open position. The setting adapter 78 also provides a travel stop 82 positioned to limit the travel of piston 66 when shifted to the open position, thus protecting spring 76. By way of example, spring 76 may comprise a coil spring positioned around internal body 70.

[0028] In the embodiment illustrated, pressure equalizer sub 40 also may comprise a collet 84 used to releasably attach liner wiper plug 38 or another running string component. In the example illustrated, collet 84 comprises a collet base 86 secured to external body 68 via threaded engagement or another suitable attachment mechanism. The collet 84 may further comprise a plurality of collet fingers 88 oriented to releasably engage the liner wiper plug 38. In this example, the liner wiper plug 38 is secured to pressure equalizer sub 40 for selective hydraulic release. The collet release may be pressure activated within the liner wiper plug 38 so as to separate the liner wiper plug release function from actuation of the pressure equalizer sub 40 between closed and open positions.

[0029] With additional reference to the enlarged cross-sectional portion of Figure

4, the illustrated embodiment of piston 66 comprises a piston base portion 90 and a piston stop portion 92. The piston stop portion 92 extends in a radial direction, e.g. a radially outward direction, from the base portion 90. The piston stop portion 92 is appropriately sized to engage travel stop 82 when piston 66 is shifted to an open position, as illustrated in Figure 5. In the embodiment illustrated, a check seal 94 is mounted on piston 66. For example, check seal 94 may be mounted along an exterior of piston 66 for sealing engagement with a corresponding seal surface 96, e.g. seal bore, disposed along an interior surface of external body 68. Thus, check seal 94 is able to form a seal between piston 66 and external body 68 when piston 66 is in a closed position, as illustrated in Figure 4.

[0030] In the embodiment illustrated, the pressure equalizer sub 40 further comprises an outer seal 98 disposed between piston 66 and external body 68. For example, outer seal 98 may be mounted along an exterior of piston 66 for sealing engagement with a corresponding seal surface 100 disposed along an interior surface of external body 68. As illustrated, the pressure equalizer sub 40 also comprises an inner seal 102 disposed between piston 66 and internal body 70. For example, the inner seal 102 may be mounted along an exterior surface of internal body 70 for sealing engagement with a corresponding seal surface 104 disposed along an interior surface of piston 66.

[0031] As further illustrated in Figure 6, piston 66 also comprises a piston flow port 106 located between the outer seal 98 and the check seal 94. To provide a greater flow area, the piston flow port 106 may comprise a plurality of flow ports 106. The flow ports 106 work in cooperation with external body pressure ports 72 and internal body flow ports 74 to establish a flow path from exterior 60 to interior 62 when piston 66 is shifted to the open position illustrated in Figure 5. Establishing the flow path from exterior 60 to interior 62 enables the desired equalization of pressures between exterior 60 and interior 62. Thus, piston 66 and check seal 94 (along with outer seal 98 and inner seal 102) are able to function as a check valve which prevents flow from interior 62 to exterior 60 while allowing flow from exterior 60 to interior 62 when a sufficient pressure differential is developed between exterior 60 and interior 62. The sufficient pressure differential causes piston 66 to shift from the closed position illustrated in Figure 4 to the open position illustrated in Figure 5. [0032] To facilitate controlled flow and shifting of piston 66, the pressure equalizer sub 40 may comprise additional flow control features. For example, the piston flow port or ports 106 and the internal body flow port or ports 74 may be elongated in different directions. In some applications, the piston flow ports 106 may be elongated in a first direction and the internal body flow ports 74 may be elongated in a second direction generally transverse to the first direction. In the specific embodiment illustrated, the piston flow ports 106 are elongated in a direction generally perpendicular to a longitudinal axis of the pressure equalizer sub 40 and the internal body flow ports 74 are elongated in a direction generally parallel to the longitudinal axis of pressure equalizer sub 40.

[0033] Examples of other flow control features include a flow chamber 108 located within external body 68 at a position downstream of the pressure port 72. The flow chamber 108 is located in a flow path from the pressure port 72 to the internal body flow port 74 and provides a region of relatively increased volume along this flow path to promote smooth actuation of piston 66. Another flow control feature may comprise an angled surface 110 located at a leading nose 112 of piston 66. The angled surface 110 is oriented to incrementally increase flow area as the piston is transitioned against spring 76 and moved toward the full open position illustrated in Figure 5.

[0034] The pressure differential between the exterior/annulus 60 and the interior

62 used to actuate piston 66 may be established by choosing an appropriate spring 76. For example, spring 76 may be selected to provide sufficient bias to the closed position and resistance to movement until the pressure at exterior 60 is sufficiently higher than the pressure in interior 62. Depending on the application, the pressure differential may be in a variety of ranges between, for example, 20 psi (138 kPa) and 110 psi (759 kPa). A specific example involves selecting spring 76 to allow actuation of piston 66 from the closed position (Figure 4) to the open position (Figure 5) upon occurrence of a pressure differential in the range of 60-70 psi (413-483 kPa). However, other pressure differential ranges may be selected depending on the parameters of a given application. When the pressure differential is less than this selected actuation level, spring 76 provides sufficient force to maintain piston 66 in the closed position and to ensure the flow path between exterior 60 and interior 62 is not open, thus containing pressure along interior 62.

[0035] In the embodiment illustrated, piston 66 is constructed so that an internal pressure affected area 114 is balanced with an external pressure affected area 116 while spring 76 provides sufficient force to achieve the desired opening pressure differential for a given application. If the pressure affected areas 114, 116 and the spring force established by spring 76 are not balanced, piston 66 may become much more sensitive to the effects of pressure at exterior 60 and interior 62.

[0036] The check seal 94, outer seal 98 and inner seal 102 provide pressure isolation when the piston 66 is located at specific axial positions. As the piston 66 moves to allow pressure equalization via pressure discharge from exterior 60 to interior 62, the flow porting is gradually exposed. In other words, the flow area through pressure ports 72, piston flow ports 106, and internal body flow ports 74 gradually increases as the piston 66 is shifted toward the open position. This gradual exposure of the pressure equalization flow porting facilitates valve stability. Additionally, seal bore surface 96 may be sized to allow check seal 94 to travel over a sufficient, predetermined distance before opening a flow path between exterior 60 and interior 62. This extended travel combined with the gradual exposure of the flow porting prevents valve sensitivity to dynamic flow effects and pressure fluctuations. Otherwise, the valve function could be detrimentally affected because the valve/piston 66 could repeatedly cycled through stages of initially cracking open, allowing a small amount of bypass flow, and then suddenly closing.

[0037] A variety of features may be used individually or in combination to facilitate the function of pressure equalization sub 40. For example, piston 66 provides a check seal function which allows flow in one direction upon activation via a sufficient pressure differential between exterior 60 and interior 62. Additionally, the gradual exposure to pressure equalization flow and the routing of the flow through pressure ports 72, into flow chamber 108, through piston flow ports 106, through internal body flow ports 74, and into interior 62 enhances smooth valve actuation with minimal pressure fluctuations. The arrangement of ports and the elongated, transversely oriented piston flow ports 106 with respect to internal body flow ports 74 optimize a desired flow area. Similarly, the piston stop portion 92 and corresponding travel stop 82 enable the setting of a range of motion for piston 66 which protects spring 76 and enhances desired valve actuation.

[0038] Various pressure equalizer sub features are discussed in greater detail below. For example, the ability of piston 66 to travel over a predetermined distance before exposing flow porting enables gradual loading of spring 76 and piston 66 before disengaging check seal 94. As the check seal 94 begins to disengage from the seal bore surface 96, the angled surface 110 provides a gradual increase in flow as the piston 66 continues to travel to the open position. The gradual increase allows a small amount of bypass flow to fill flow chamber 108 upstream of the piston flow port 106. Once the check seal 94 is completely out of the seal bore surface 96, the angled surface 110 on leading nose 112 continues to incrementally increase the flow area until the valve assembly 64 reaches a full open position and piston stop portion 92 lands against travel stop 82.

[0039] The travel of piston 66 and the porting which establishes the flow area from exterior 60 to interior 62 ensures the velocities of the fluid traveling to interior 62 are managed while still accommodating a desired flow volume in a given discharge time. In a specific example, elongated piston flow ports 106 and elongated internal body flow ports 74 are oriented with their elongations at 90° with respect to each other. This helps ensure that regardless of the clocking of the valve piston 66 on the internal body 70, adequate flow area is maintained into and out of flow chamber 108. It also helps ensure that the velocities of fluid flow in this area are managed, e.g. do not allow detrimental erosion. In at least some embodiments, when piston 66 is in a closed state (Figure 4) the piston flow ports 106 and the internal body flow ports 74 do not overlap each other. However, once the check seal 94 begins to allow bypass flow, the position of piston flow ports 106 and internal body flow ports 74 align and overlap during subsequent piston travel.

[0040] The volume of flow chamber 108 and the flow areas into and out of chamber 108 may be selected so that flow chamber 108 acts as a hydraulic dampener. The hydraulic dampening further increases the stability of piston 66 and decreases sensitivity to flow during piston travel. Even under pressure, for example, the discharge of fluid from flow chamber 108 during transition of piston 66 to the closed position tends to slow this transition and to provide a hydraulic dampening, thus increasing piston stability.

[0041] As the pressure in interior 62 increases relative to the exterior pressure to an amount less than the predetermined threshold, e.g. 60-70 psi, the spring force exerted by spring 76 along with pressure on the upstream side of piston 66 shifts the piston 66 back to the closed or seated position illustrated in Figure 4. As discussed above, piston 66 may be constructed to establish the same internal and external pressure affected areas 114, 116 on the upstream and downstream sides. The active diameter of the piston is the same for both directions. Effectively, the pressure equalizer sub enables pressure equalization in a passive manner that does not involve operator action.

[0042] Additionally, the positive stop provided by travel stop 82 prevents over travel of the piston 66 and ensures that the spring 76 does not transition to its solid height and thus risk becoming overstressed. The travel stop 82 also serves to limit valve/piston travel so as to control both flow area and proper seal engagement with piston 66. In the illustrated embodiment, the stop portion 92 of piston 66 is constructed to provide a pressure balanced stop portion by allowing bypass pressure to engage both sides of the piston stop portion 92. This approach removes any added force application from the larger diameter of piston stop portion 92 and maintains the original seal diameter for internal pressure affected area 114. [0043] Effectively, stop portion 92 and cooperating travel stop 82 limit travel of piston 66, ensure manageable valve spring stresses, ensure manageable contact stresses between valve piston 66 and travel stop 82 of setting adapter 78, and maintain pressure balance on both sides of the piston stop portion 92. The clearance between the outside diameter of the stop portion 92 and the corresponding inside diameter of external body 68 is selected to make sure debris does not obstruct or otherwise detrimentally impact seating of piston 66. The larger diameter stop portion 92 further facilitates assembly of pressure equalizer sub 40 by preventing the check valve assembly 64 from being assembled backwards, thus helping to error-proof the assembly process.

[0044] Another feature that may be incorporated into pressure equalizer sub 40 to improve robustness of the structure comprises pressure relief flow channels 118, as illustrated in Figure 7. The pressure relief flow channels 118 may be formed in the internal body 70. The flow channels 118 are sized to allow the pressure volume in the chamber containing spring 76 to be relieved during valve piston travel. However, the size of flow channels 118 also is sufficiently small to limit the size of debris and dense liquids that could otherwise be trapped within the chamber containing spring 76. Such trapped debris and dense liquid could potentially have a detrimental effect on operation of the pressure equalizer sub 40.

[0045] The selective actuation of check valve assembly 64 via piston 66 may be accomplished with various components arranged in a number of configurations. The individual components also may be constructed in several configurations. For example, piston 66 may comprise an annular piston or it may have a variety of other configurations to control pressure equalization along a flow path between the exterior and interior of the pressure equalizer sub. In some applications, the piston may be actively controlled via, for example, a hydraulic or electronic control mechanism. Additionally, the

configuration of the internal body, external body, setting adapter, and spring may vary depending on the parameters of a given application and environment. Similarly, the materials used to construct the various components may be selected according to the pertinent parameters. [0046] It should be further noted that the overall configuration of the liner hanger system may differ from one well application to another. For example, the type and arrangement of components along the liner hanger system can vary between different applications. Similarly, the overall configuration of the running string may change from one well application to another. The type and arrangement of components may vary according to the functionality of the running string and according to other parameters of a given application and/or environment.

[0047] Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.

Citas de patentes
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Clasificaciones
Clasificación internacionalE21B43/10, E21B23/00
Clasificación cooperativaE21B2034/007, E21B43/10, E21B34/14
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