WO2024123587A1 - Split stuffing box system and method - Google Patents

Abstract

A technique facilitates use of a stuffing box by enabling passage of coated intervention cable with an expanded diameter sub. The technique employs a stuffing box constructed to provide sealing engagement with the coated intervention cable while also enabling passage of the expanded diameter sub. The stuffing box comprises an external housing having a longitudinal passage therethrough. Additionally, the stuffing box comprises a plurality of split components disposed along the longitudinal passage. Each of the split components is split through at least one location to allow expansion of the split component, assembly over the coated cable, and insertion into the external housing after the expanded diameter sub passes through the stuffing box.

Description

SPLIT STUFFING BOX SYSTEM AND METHOD

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/386690, which was filed on December 9, 2022 and is incorporated herein by reference in its entirety.

BACKGROUND

[0002] In many oil and gas well applications, various types of equipment may be used to contain and isolate pressure in the wellbore. During a wireline intervention operation, for example, a stuffing box is employed as part of the pressure control equipment. The stuffing box comprises a packer system which seals around the wireline cable as it is fed downhole or retrieved after the wireline intervention operation. With some types of intervention cable, e.g. Streamline™ cable available from Schlumberger Technology Corporation, the cable is provided with a polymer coating to prevent gas ingress into the wire strands of the cable. However, the cable termination is sealed with a sealed sub, e.g. a sealed head, to prevent gas from migrating into the coated intervention cable. The sealed sub tends to have a substantially larger diameter than the coated cable diameter. As a result, the sealed sub cannot pass through the stuffing box and the cable must be cut and then resealed which leads to substantial additional time, expense, and wear on the coated cable.

SUMMARY

[0003] In general, a system and method facilitate use of a stuffing box by enabling passage of coated intervention cable with an expanded diameter sub. The technique employs a stuffing box constructed to provide sealing engagement with the coated intervention cable while also enabling passage of the expanded diameter sub. The stuffing box comprises an external housing having a longitudinal passage therethrough. Additionally, the stuffing box comprises a plurality of split components disposed along the longitudinal passage. Each of the split components is split through at least one location to allow expansion of the split component, assembly over the coated cable, and insertion into the external housing after the expanded diameter sub passes through the stuffing box.

[0004] 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

[0005] 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:

[0006] Figure l is a cross-sectional illustration of an example of a stuffing box having split components to enable passage of an expanded diameter sub of a coated intervention cable, according to an embodiment of the disclosure;

[0007] Figure 2 is a cross-sectional view of an upper portion of the stuffing box illustrated in Figure 1, according to an embodiment of the disclosure;

[0008] Figure 3 is a cross-sectional view of a middle portion of the stuffing box illustrated in Figure 1, according to an embodiment of the disclosure; [0009] Figure 4 is a cross-sectional view of a lower portion of the stuffing box illustrated in Figure 1, according to an embodiment of the disclosure;

[0010] Figure 5 is an orthogonal view of an example of a split component which may be used within the stuffing box, the split component having a single, angled split to enable widening of the split component for assembly over the coated intervention cable, according to an embodiment of the disclosure;

[0011] Figure 6 is another example of a split component which may be used within the stuffing box, the split component having a single split to enable widening of the split component for assembly over the coated intervention cable, according to an embodiment of the disclosure;

[0012] Figure 7 is another example of a split component which may be used within the stuffing box, the split component having a double split to enable widening of the split component for assembly over the coated intervention cable, according to an embodiment of the disclosure; and

[0013] Figure 8 is a cross-sectional view of an example of a split check valve for use within the stuffing box, according to an embodiment of the disclosure.

DETAILED DESCRIPTION

[0014] 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.

[0015] The disclosure herein generally involves a system and method which facilitate use of a stuffing box by enabling passage of an expanded diameter sub connected to a coated intervention cable, e.g. a Streamline™ cable available from Schlumberger Technology Corporation. The expanded diameter sub may be in the form of a head having a substantially larger diameter than the diameter of the coated cable, e.g. 1.75 inches for the sub versus 0.35 inches for the coated cable. The technique employs a stuffing box constructed with split, expandable internal components which may be assembled over the coated intervention cable. This enables passage of the expanded diameter sub through an interior of the stuffing box without cutting the cable as described in greater detail below. It should be noted that “passage” of the expanded diameter sub refers to the positioning of the expanded diameter sub below the stuffing box. Completing assembly of the stuffing box often occurs after the expanded diameter sub is below the stuffing box, i.e. on a bottom side of the split, expandable internal components.

[0016] According to an embodiment, the stuffing box comprises an external housing having a longitudinal passage therethrough. Additionally, the stuffing box comprises a plurality of split components disposed along the longitudinal passage. Each of the split components is split through at least one location to allow expansion of the split component, assembly over the coated cable, and insertion into the external housing above the expanded diameter sub, thus allowing the expanded diameter sub to be moved down through the stuffing box without cutting the cable. The ability of the sub to pass completely through the stuffing box without cutting or splicing the cable reduces complexity, saves time on the job site, and extends the life of the coated intervention cable.

[0017] Referring generally to Figure 1, a system 20 for pressure control contains and isolates pressure in a borehole, e.g. a wellbore. In this example, the system 20 comprises pressure control equipment 22 including a stuffing box 24. The pressure control equipment 22 is mounted above a well 26 which includes a borehole 28, e.g. a wellbore, extending down into a subterranean formation. The stuffing box 24 is constructed to maintain a seal against an intervention cable 30 deployed down through the pressure control equipment 22 and into the well 26 for performance of a desired intervention operation. [0018] In the example illustrated, the intervention cable 30 is shown schematically in the form of a coated intervention cable. This type of intervention cable often comprises an internal conductive cable 32 formed of conductive strands encapsulated and protected by a surrounding coating 34, e.g. a polymeric coating. The coated intervention cable 30 provides structural support for deploying various types of intervention tools downhole into well 26 while also enabling the flow of power and/or data signals via the internal conductive cable 32.

[0019] The lower, terminal end of the coated intervention cable 30 is protected by a sub 36, sometimes referred to as a head, which tends to have a substantially larger diameter than that of the coated intervention cable 30. The surrounding coating 34 prevents undesirable gas ingress into the wire strands of the internal conductive cable 32, while the enlarged diameter sub 36 seals the cable termination end to keep undesirable gas from migrating between the internal conductive cable 32 and the surrounding coating 34. One example of coated intervention cable 30 is Streamline™ cable available from Schlumberger Technology Corporation, however the technique described herein may be used with a variety of intervention cable types for many types of intervention operations.

[0020] According to the embodiment illustrated in Figure 1, the stuffing box 24 comprises an external housing 38 having a longitudinal passage 40 therethrough. The external housing 38 may be constructed in a variety of configurations with suitable components for a given intervention job. By way of example, the external housing 38 may be constructed with a plurality of body portions 42 secured together sequentially via connectors 44, e.g. threaded connectors. A separate coupling mechanism 45, e.g. a threaded coupling mechanism, may be secured at a lower end of the external housing 38 to enable assembly of the stuffing box 24 onto the next adjacent component of pressure control equipment 22.

[0021] The separable body portions 42 may be constructed to facilitate assembly of a variety of internal components 46. For example, appropriate internal components 46 may be stacked into a lower body portion 42. The next sequential body portion 42 may then be coupled to the lower body portion 42 to enable stacking of additional internal components 46 into that next sequential body portion 42. This process is continued until the stuffing box 24 is fully assembled.

[0022] The external housing 38 also may comprise other features, such as lateral passages 48, e.g. weep holes, extending laterally through the walls forming at least some of the body portions 42. In some embodiments, the lateral passages 48 may be mated with port savers 50 which, in turn, may be connected with suitable couplers 52, e.g. quick couplers, for easy connection to corresponding hoses or other tubing.

[0023] With additional reference to Figures 2-4, the internal components 46 comprise a plurality of split components 54 which may be expanded, e.g. split apart, to enable assembly of those components around the coated intervention cable 30 above the expanded diameter sub 36. This allows the expanded diameter sub 36 to be moved down through the larger longitudinal passage 40 without having to pass through the split components 54. The split components 54 may simply be assembled around the coated intervention cable 30 above the expanded diameter sub 36 and then properly positioned within the external housing 38.

[0024] It should be noted Figures 2-4 represent cross-sectional views of portions of the stuffing box 24, namely the upper portion, the middle portion, and the lower portion, respectively. In these illustrations, the cross-sectional views are taken along the split of many of the split components 54 and effectively show one half of such split components 54. In some embodiments, the components 54 may be split at other locations, e.g. locations which do not result in the component 54 effectively being cut in half. Additionally, a single split on one side of the component 54 may be used for certain flexible internal components, while additional splits, e.g. three or more splits, may be used for some types of internal components. [0025] Examples of split components 54 which facilitate deployment of coated intervention cable 30 include split packers 56 (see Figures 2 and 3). The split packers 56 may be formed from suitable elastomeric material selected to seal against the exterior of the coated intervention cable 30. In the illustrated example, the split packers 56 are split in half axially and received in packer housings 58. The packer housings 58 may be constructed as pistons which are spring biased via suitable springs 60. The spring bias may be applied to help maintain each packer 56 in the desired sealing engagement with cable 30. For example, the spring bias may be used to squeeze the elastomeric material of packers 56 so as to force the material against the coated intervention cable 30.

[0026] Another example of split components 54 comprises a split guide entry 62 and a corresponding line wiper 63 which may be secured at a top end of external housing 38 via a fastener 64, e.g. a threaded fastener. By way of example, each of the split guide entry 62 and line wiper 63 may be formed as two split halves which may be separated and then placed around the coated intervention cable 30 above the expanded diameter sub 36 as illustrated. The line wiper 63 and split guide entry 62 may then be inserted into their appropriate positions within external housing 38 and secured via fastener 64.

[0027] As further illustrated in Figure 4, another split component 54 may be in the form of a check valve 66 which may be positioned at a lower end of external housing 38 along the internal longitudinal passage 40. Check valve 66 functions to block or limit release of pressure and upflow of fluid through the stuffing box 24 in the event the coated intervention cable 30 is severed and dropped downhole. By way of example, the check valve 66 may be in the form of a ball check valve. One embodiment of the ball check valve 66 is described in greater detail below and includes a description of specific split check valve components which enable assembly of the check valve 66 over coated intervention cable 30 above expanded diameter sub 36.

[0028] Additional examples of split components 54 comprise split upper inserts 68 which may be positioned directly above the elastomeric element of each packer 56. By way of example, the split upper inserts 68 may be formed as two split halves which may be separated and then placed around the coated intervention cable 30 above the expanded diameter sub 36. The upper inserts 68 may then be inserted into their appropriate positions within external housing 38 during the sequential assembly of internal components 46 (including split components 54) along the interior longitudinal passage 40 of external housing 38.

[0029] Similarly, split components 54 may comprise split lower inserts 70 which may be positioned directly below the elastomeric element of each packer 56. By way of example, the split lower inserts 70 may be formed as two split halves which may be separated and then placed around the coated intervention cable 30 below the expanded diameter sub 36. The lower inserts 70 may then be inserted into their appropriate positions within external housing 38 during the sequential assembly of internal components 46/54 along the interior longitudinal passage 40 of external housing 38. In various assembly procedures, the stuffing box 24 may be assembled from bottom to top so each split lower insert 70 would be positioned in external housing 38 before (or sometimes simultaneously) with its corresponding upper insert 68.

[0030] According to an embodiment, the split upper inserts 68 and the split lower inserts 70 may be formed of metal material, e g. a copper-nickel alloy. Because of the hardness of this material, the corners/edges of material at the split can potentially damage the external surface of coated intervention cable 30. Consequently, some embodiments may employ protective split inserts 72 positioned along internal passages 74 of the inserts 68, 70. The protective split inserts 72 may be formed of softer, protective materials including plastic materials, e.g. polyetheretheretherketone (PEEK).

[0031] These protective inserts 72 also are split and may be assembled over the coated intervention cable 30 in a similar manner to that described above with respect to inserts 68, 70. Furthermore, the split protective inserts 72 may be constructed to fit more closely around the coated intervention cable 30 as compared to the upper inserts 68 and lower inserts 70 to ensure inserts 72 remain in contact with the cable 30 as it moves through the stuffing box 24. [0032] In some embodiments, the splitting of upper inserts 68 and lower inserts 70 potentially can lead to extrusion of the elastomeric material of packers 56 into the area between the split halves of the inserts 68, 70. To combat this, a flat disk 74 (see Figure 5) may be inserted between each packer 56 and the corresponding upper and lower inserts 68, 70. The flat disk 74 may be formed from a flexible material, e.g. in elastomeric material, which is split to enable placement of the flat disk 74 around the coated intervention cable 30. Because of the flexibility, some embodiments of flat disk 74 may have a single split 76 formed by a cut through one side of the flat disk 74, as illustrated in Figure 5. By way of example, the single split/cut 76 may be formed at an angle, e.g. a 45° angle. Protective placement of such flat disks 74 adjacent the upper and lower ends of each packer 56 helps prevent the undesirable extrusion of the packer material.

[0033] Referring generally to Figures 6-8, an embodiment of split ball check valve 66 is illustrated. The ball check valve 66 functions to stop the flow of wellbore fluids to the environment if the coated intervention cable 30 is severed and the upper portion of the cable 30 is pulled to the surface during an intervention operation. A ball 78 of the ball check valve 66 is moved via the escaping fluid into a position where it forms a seal and stops the unwanted upward flow of wellbore fluids.

[0034] In this example, ball check valve 66 comprises a split ball seat 80 against which the ball 78 seals if an upward flow of well fluid occurs through the ball check valve 66. The split ball seat 80 may be formed of a flexible material, e.g. an elastomeric material, and may comprise a single split 76 (see Figure 6) or a plurality of splits 76 (see two split embodiment in Figure 7). The splits 76 enable sufficient bending or spreading to allow placement of the split ball seat 80 around the coated intervention cable 30.

[0035] The ball check valve 66 also may comprise a split seat retainer 82 and a split ball retainer 84. The split seat retainer 82 and split ball retainer 84 secure the split ball seat 80 within a valve housing 86. The split ball retainer 84 also secures ball 78 within a ball retention recess 88 until the ball 78 is moved into sealing engagement with split ball seat 80. The split ball check valve components 80, 82, 84 may be secured within valve housing 86 via a snap ring 90 or other suitable retention mechanism. Similarly, the valve housing 86 may be secured within external housing 38 via suitable fastening mechanisms, such as an abutment 92 and a housing snap ring 94. It should be noted the cross-sectional view of Figure 8 is taken along a plane which illustrates the splits 76 between the separate halves of, for example, split seat retainer 82 and split ball retainer 84.

[0036] In this example, the valve housing 86 is constructed with an internal passage 96 sufficiently large to enable passing of the expanded diameter sub 36 without splitting the valve housing 86. Once the expanded diameter sub 36 is moved through the valve housing 86, the split ball seat retainer 82, split ball seat 80, and split ball retainer 84 may be assembled around the coated intervention cable 30, moved into passage 96 of valve housing 86, and secured therein via snap ring 90.

[0037] In some embodiments, the snap ring 90 may be replaced with a threaded nut or other suitable fastener which may be tightened against the split ball retainer 84 so as to compress the split ball seat 80 and improve the reliability of the seal. Similarly, the split ball seat 80 may be constructed with an outer diameter of sufficient size to interfere with the inner diameter of valve housing 86 so as to improve the seal along the outer surface of ball seat 80.

[0038] The flexible components, e.g. elastomeric components, also may be formed as multi-part components to again improve sealing. For example, the split protective disk 74 illustrated in Figure 5 and/or the split ball seats 80 illustrated in Figures 6-7 may be formed in a plurality of layers with single or plural splits 76. The layers of each split component 74, 80 are then placed against each other with the splits 76 being out of alignment. For example, single splits 76 of the multi-part components could be rotated 180° out of alignment or double splits 76 of the multi-part components could be rotated 90° out of alignment with each other. [0039] In an operational example, setting up of the stuffing box 24 may involve starting assembly at the lower body portion 42 of external housing 38. The expanded diameter sub 36 is deployed down through the internal passage 40 of the lower body portion 42 so that the split check valve 66 may be assembled around the coated intervention cable 30 and secured into the lower body portion 42 of external housing 38, as illustrated in Figure 8.

[0040] Subsequently, the next sequential body portion 42 may be assembled to the lower body portion 42. This allows the corresponding internal split components 54, e.g. lower split packer 56, to be assembled around the coated intervention cable 30 and properly held in place by this next sequential body portion 42. This process is continued until all of the body portions 42 and internal components 46, 54 have been assembled to complete the stuffing box 24. The splitting of components 54 which would otherwise have too small of an opening to accommodate the expanded diameter sub 36 enables the expanded diameter sub 36 to effectively be passed through these components 54. After this passage, the split components 54 are simply assembled around the coated intervention cable 30 above the expanded diameter sub 36. As a result, there is no need to sever the coated intervention cable 30 when preparing for an intervention operation on well 26.

[0041] Depending on the specific well intervention operation and well equipment, the overall system 20 may be adjusted and various additional or alternate components may be utilized. For example, a variety of intervention tools may be deployed downhole via coated intervention cable 30. Additionally, the pressure control equipment 22 may comprise many types of pressure containment devices, valves, control systems, and/or other components selected for a given intervention operation.

[0042] Furthermore, the components and arrangement of stuffing box 24 may vary according to the parameters of a given environment and/or intervention operation. For example, the stuffing box 24 may have a single packer 56 or various other numbers of packers 56. A variety of seal types and seal placements may be used to provide desired seals between the components of stuffing box 24 (see various illustrated seals in Figures 1-4 and 8). Some of the split components 54 may be secured together via threaded fasteners or other suitable fasteners after assembly around the coated intervention cable 30. Various types of check valves 66 may be employed. The sequence of assembly and arrangement of internal components also may be changed to accommodate component size and shape or to achieve specific goals with respect to various types of intervention operations.

[0043] 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.

Claims

CLAIMS What is claimed is:

1. A system for pressure control with respect to a wellbore, comprising: a stuffing box constructed to provide sealing engagement with a coated intervention cable coupled with an expanded diameter sub, the stuffing box comprising: an external housing having a longitudinal passage therethrough; and a plurality of split components, each split component being split through at least one location to allow expansion of the split component and subsequent assembly over the coated intervention cable above the expanded diameter sub to enable the expanded diameter sub to pass through the stuffing box.

2. The system as recited in claim 1, wherein the plurality of split components comprises a split packer.

3. The system as recited in claim 1, wherein the plurality of split components comprises a plurality of split packers.

4. The system as recited in claim 1, wherein the plurality of split components comprises a split check valve.

5. The system as recited in claim 2, wherein the plurality of split components comprises a split guide entry.

6. The system as recited in claim 5, wherein the plurality of split components comprises a split line wiper. The system as recited in claim 6, wherein the plurality of split components comprises a split insert. The system as recited in claim 6, wherein the plurality of split components comprises a plurality of split inserts. The system as recited in claim 7, wherein the split insert comprises an elastomeric material. A system, comprising: a stuffing box constructed to provide sealing engagement with a coated intervention cable having an expanded diameter sub, the stuffing box comprising: an external housing having a longitudinal passage therethrough; and a plurality of split components including a check valve, the check valve being split through at least one location to allow expansion of the split check valve and subsequent assembly over the coated intervention cable above the expanded diameter sub, thus enabling the expanded diameter sub to pass through the stuffing box. The system as recited in claim 10, wherein the check valve is a ball check valve. The system as recited in claim 11, wherein the ball check valve comprises a split ball seat. The system as recited in claim 12, wherein the ball check valve comprises a split ball retainer. The system as recited in claim 13, wherein the ball check valve comprises a split ball seat retainer. The system as recited in claim 10, wherein the plurality of split components comprises a split packer. The system as recited in claim 15, wherein the plurality of split components comprises a plurality of split inserts. The system as recited in claim 16, wherein the plurality of split components comprises a split guide entry. A method, comprising: providing pressure control equipment with a stuffing box at a well; expanding split internal components of the stuffing box; assembling the split internal components around a coated intervention cable above an expanded diameter sub positioned at a lower end of the coated intervention cable; deploying the expanded diameter sub to a lower end of an external housing of the stuffing box ahead of the split internal components for movement down into the well without cutting of the coated intervention cable; and securing the split internal components within the external housing of the stuffing box. The method as recited in claim 18, wherein expanding comprises expanding a split check valve. The method as recited in claim 19, wherein expanding comprises expanding a split packer.