EMERGENCY ELASTOMER INJECTION SYSTEM FOR USE ON E-LINE AND BRAIDED CABLE
A system and method for sealing a passage around a cable is disclosed. Embodiments of the system can include an axial passage, such as a conduit and subsea wellhead housing connected to a wellbore, that can have a cable extending therethrough. The system can include an upper restrictor and a lower restrictor for closing the axial passage. An injection module having an injector and a reservoir can be fluid communication with the axial passage at an axial location between the upper restrictor and the lower restrictor. The injector can discharge a curable sealant initially stored in the reservoir into the axial passage so that at least a portion of the sealant contacts the cable at the axial location of the restrictor while the cable remains static.
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1. Field of the Invention
The present invention relates in general to mineral recovery wells, and in particular to an apparatus and method for sealing a wellbore.
2. Brief Description of Related Art
Wire line operations in a wellbore typically use one of three types of wire line—slick line, e-line, or braided cable. In order to maintain pressure control during these operations, and thus prevent pressurized fluid escaping from the wellbore, the wire line is passed through a pressure controlling device. Devices for preventing pressure from escaping from the well bore include wire line blowout preventers (“BOP”), pressure control heads (“PCH”), lower riser packages (“LRP”), and lubricators.
These pressure control devices employ different methods of pressure control including rams, pressure energized packing sets, and grease. These methods, although different, follow the same principals in that they all form a seal around the outside of the wire line. It therefore follows that the outer profile and indeed construction of the wire line can significantly alter the effectiveness of the seal generated. For example, on braided cable, the structure is such that it has a labyrinth of leak paths so even with tight sealing on the outer diameter, leakage is possible through the gaps which exist in the structure of the cable itself In some cases grease is injected into the cable, under high pressure, to fill the void, thus reducing the ingress and leakage of wellbore fluids through the cable. Unfortunately, the grease will follow the same principle of leakage through the labyrinth and ultimately be depleted over the duration of the operation. The grease must be replenished to maintain the seal for a length of time. Therefore, it is desirable to have a semi-permanent seal for use in emergency situations.
SUMMARY OF THE INVENTIONEmbodiments of the claimed invention relate primarily to sealing in an emergency. Because e-line and braided cable can have a labyrinth of leak paths, conventional sealing techniques require constant grease injection in order to maintain a seal. Under certain circumstances, such as an emergency condition, the seal around the wire line may be required to maintain pressure control for a significant length of time. The grease supply will therefore deplete and may be not be replenished or maintain enough pressure to seal. Embodiments of the claimed invention can include a cylinder of sealant, such as an elastomer, epoxy, or some other plastic, any of which can be stored in a liquid or paste form. In some embodiments, the sealant can include particles of predetermined sizes. The sealant can be stored in a two- part resin form, where it can remain in a fluid state for a long period of time. Upon actuation of an emergency sequence, an injection module would deploy the pressurized sealant to a pre-defined chamber wellbore member via one or several ports. Upon injection, it would begin to chemically change and increase in viscosity until it is set, ultimately forming a seal within the labyrinth of the e-line or braided cable.
So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and is therefore not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and the prime notation, if used, indicates similar elements in alternative embodiments.
Referring to
As best shown in
Upper lubricator 112 and lower lubricator 114 can be used to form a seal against cable 100. As one of skill in the art will appreciate, lubricators 112 and 114, which can be conventional, can include fingers for imparting grease to cable 100 as cable 100 moves through PCH 102. The grease can fill gaps 108 within cable 100 and along the outer diameter of cable 100. Lubricators 112 and 114 can form a seal against cable 100 during routine operations.
During a high pressure condition in the wellbore, the seal between cable 100 and lubricators 112, 114 may be inadequate. A restrictor, such as pressure energized packing sets 116, can be used to establish a more robust seal around cable 100. In one embodiment, packing sets 116 can include chamber 118, connected to pressure port 120. Sealing face 122 is the inner diameter wall of chamber 118 and, thus, faces radially inward toward the axis of bore 104. As best shown in
During a period of prolonged exposure to a high pressure condition, the grease imparted by packing sets 112 and 114 may be insufficient to maintain a seal. The high pressure can, over time, displace the grease from gaps 108, in which case wellbore fluid can flow around and through cable 100 and past packing set 116 to ultimately leak out of the wellbore. In some circumstances, such a prolonged high pressure condition can be an emergency condition.
An injection module 124 can be connected to PCH 102. Injection module 124 is used to inject a curable sealant 126 into an axial passage such as bore 104 so that sealant 126 contacts at least a portion of cable 100. In one embodiment, sealant 126 is injected into a portion of bore 104 that is located between two flow restrictors such as, for example, packing sets 116. In some embodiments, the sealant can be injected into other portions of the wellbore or riser, provided that sealant 126 contacts cable 100. The flow restrictors force the sealant to flow around and through cable 100. Without the flow restrictors, sealant 126 could flow freely out of bore 104 rather than being injected into gaps 108.
As shown in
Plunger 134 can be actuated by any of a variety of techniques. For example, plunger 134 could be connected to a hydraulic piston and hydraulic pressure from the surface platform or from a remotely operated vehicle (“ROV”) (not shown in
Sealant 126 can be any type of sealant for sealing gaps 108 or forming a seal between the outer diameter of cable 100 and the cable-facing surface of a restrictor, such as sealing face 120. Sealant 126 can be stored as a liquid or paste, and can remain in a fluid state for a long period of time. Sealant 126 can chemically change upon injection into bore 104 so that it begins to harden and increase in viscosity. In one embodiment, sealant 126 can be an elastomer that sets, or hardens, under a pre-determined condition. For example, the elastomer could set after reaching a certain temperature or pressure. In another embodiment, the elastomer could set upon being exposed to a particular chemical. In the embodiment wherein the elastomer sets in response to reaching a certain pressure, the pressure can be selected so that bore 104 can be filled with the elastomer and the elastomer will set only after the pressure is sufficiently high to cause a portion of the elastomer to enter gaps 108 or enter the gap that may exist between cable 100 and sealing face 120. In one embodiment, sealant 126 can be a curable sealant that hardens after being injected, such as, for example, a curable polymer, a binary epoxy, or two-part resin, wherein the sealant is initially stored as two separate liquids. As shown in
In one embodiment, sealant 126 can include a fluid suspended particulate such that, upon injection, a portion of the particulate will lodge in flow restrictions such as gaps 108 or the annular space between cable 100 and sealing face 120. As shown in
In one embodiment, as shown in
In one embodiment, the fluids can be a solvent and an elastomer, or a solvent and an epoxy. For example, reservoir 152 can initially contain a solvent that is suitable to displace grease, while reservoir 156 initially contains an elastomer sealant. The solvent, such as, for example, methanol, can be injected into bore 170 first, and used to displace grease from cable 174. After a predetermined condition, such as a given amount of time, the elastomer from reservoir 156 can be injected into bore 170 to fill gaps in cable 174. This can be useful when, for example, grease is occupying the gaps in cable 174 and that grease would prevent the elastomer from filling the gaps. Because the grease can be displaced over time, and thus undermine the seal, it can be beneficial to displace the grease before injecting the elastomer. In embodiments that do not use a solvent, the pressure of the sealant can displace some or all of the grease as the sealant is injected into the bore. In one embodiment, a solvent from a first reservoir 152 can be used to first displace and flush any grease that may be on cable 174, followed an etching agent from the second reservoir 156. The etching agent can be used to clean and prepare surfaces within cable 174 and within bore 170 to better adhere to the sealant. A sealant from a third reservoir (not shown) can then be injected under high pressure to fill the gaps and adhere to the surfaces of cable 174 and bore 170.
Still referring to
The sealant injection system is not limited to use in a pressure control head. It can be used with any of a variety of wellbore devices, especially devices that constrict the bore around a wireline. As shown in
Still referring to
Referring to
Referring to
Referring back to
The wellbore restrictors, such as packing sets 116, can be actuated so that sealing face 122 of the restrictors move radially toward the center of bore 104. Curable sealant can be injected from injection module 124, through injection port 128 so that curable sealant 124 flows around cable 100 between the upper and lower passage restrictors. In some embodiments, the restrictors can be actuated before curable sealant 124 is injected.
In some embodiments, the restrictors can be actuated after curable sealant 124 is injected. Curable sealant 124 can fill bore 104, permeate gaps 108 (
In embodiments, curable sealant 124 can be stored as two or more separate components in two or more separate vessels 152, 156 in the reservoir. The two or more separate components 154, 158 can react to form the curable sealant when the components are mixed prior to or during the injection of the components through injection port 128. In embodiments, cable 100 can include a braided material and curable sealant 124 can be injected into the braided material. In embodiments, cable 100 can be remain axially stationary during the injection of curable sealant 124 and during the actuation of the restrictors. In some embodiments, cable 100 can be axially moved after the injection of curable sealant 124 so that the portion of cable 100 having sealant 124 is moved toward a restrictor prior to actuating the restrictor. In some embodiments, the reservoir can include a first and second container. The first container can initially contain a solvent and the second container can initially contain curable sealant 124. The solvent can be injected before the sealant to remove grease from cable 100, and then curable sealant 124 can be injected.
While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.
Claims
1. An apparatus for sealing a passage around a cable, the apparatus comprising:
- an axial passage adapted to have the cable passing therethrough, the cable having a plurality of strands;
- an upper restrictor and a lower restrictor for closing the axial passage, the upper and lower restrictors occupying the annular space between an inner diameter of the axial passage and an outer diameter of the cable; and
- an injection module having an injector and a reservoir, the injection module being in fluid communication with the axial passage at an axial location between the upper restrictor and the lower restrictor, the injector discharging a sealant initially stored in the reservoir into the axial passage so that at least a portion of the sealant contacts the cable at the axial location of the restrictor while the cable remains static.
2. The apparatus according to claim 1, wherein the upper restrictor and the lower restrictor cause the sealant to flow between at least a portion of the plurality of strands.
3. The apparatus according to claim 1, wherein the upper restrictor comprises an upper pair of rams and the lower restrictor comprises a lower pair of rams, each pair of rams moving axially inward to a constricted position to constrict the bore, the constricted position reducing the flow of sealant out of the axial passage, thereby forcing at least a portion of the sealant to enter a plurality of voids between the strands.
4. The apparatus according to claim 1, wherein reservoir comprises a first chamber and a second chamber, the first chamber initially having a solvent, the solvent being a fluid that removes grease, and the second chamber initially having the sealant, wherein the solvent is discharged into the axial passage before the sealant is discharged into the axial passage.
5. The apparatus according to claim 1, wherein the reservoir is located in a remotely operated vehicle, the remotely operated vehicle stabbing into a fluid passage in communication with the axial passage.
6. The apparatus according to claim 1, wherein the sealant comprises suspended particulate, the suspended particulate lodging in flow restrictions within the plurality of strands of the cable.
7. The apparatus according to claim 1, further comprising a sleeve in the passage adapted to pass the cable therethrough, the sleeve adapted to initially have an inner diameter greater than an outer diameter of the cable, and being deformable to reduce the annular space between an inner diameter of the sleeve and the outer diameter of the cable prior to discharging the sealant.
8. The apparatus according to claim 1, wherein the sealant is a curable polymer that hardens after being injected.
9. The apparatus according to claim 1, wherein at least a portion of the sealant displaces grease located within the plurality of braided strands.
10. A method for sealing around a cable extending through a conduit and a subsea wellhead assembly into a wellbore, the method comprising:
- (a) providing upper and lower passage restrictors in the conduit above the wellhead assembly;
- (b) providing an injection module connected to a port through a sidewall in the conduit, the port being located between the upper passage restrictor and the lower passage restrictor, the injection module having an injector and a reservoir, the reservoir initially containing a curable sealant;
- (c) actuating the wellbore restrictor to cause the upper and lower passage restrictors to move radially toward the center of the wellbore; and
- (d) injecting the curable sealant from the injection module through the port in the conduit around the cable between the upper and lower passage restrictors.
11. The method according to claim 10, wherein the curable sealant is stored as two or more separate components in two or more separate vessels in the reservoir, the two or more separate components reacting to form the curable sealant, and wherein step (d) comprises mixing the two or more separate components prior to injecting the curable sealant.
12. The apparatus according to claim 10, wherein the cable comprises a braided material, and wherein step (d) includes injecting the curable sealant into the braided material.
13. The apparatus according to claim 10, wherein the cable remains axially stationary during steps (c) and (d).
14. The apparatus according to claim 10, wherein step (d) occurs prior to step (c).
15. The apparatus according to claim 10, wherein the reservoir comprises a first and second container, the first container initially containing a solvent and the second container initially containing the curable sealant, and wherein step (d) comprises first injecting the solvent to remove a grease from the cable and then injecting the curable sealant.
16. An apparatus for sealing around a cable extending through a subsea wellhead assembly into a wellbore, the apparatus comprising:
- an axial passage having a conduit adapted to extend above the wellhead assembly and having an axial passage through which the cable extends,;
- a sleeve located in the passage, the cable extending through the sleeve, and the sleeve being deformable to reduce the annular space between an inner diameter of the sleeve;
- an upper restrictor comprising an upper pair of rams and a lower restrictor comprising a lower pair of rams, each of the upper pair of rams and lower pair of rams moving from a first position to a second position to deform the sleeve to occupy the annular space between an inner diameter of the axial passage and an outer diameter of the cable; and
- an injection module having an injector and a reservoir, the injection module being in fluid communication through a sidewall of the axial passage to a location within the axial passage between the upper restrictor and the lower restrictor, the injector discharging a curable sealant initially stored in the reservoir into the axial passage to seal between the cable and the sleeve.
17. The apparatus according to claim 16, wherein the cable comprises a plurality of strands and wherein upper restrictor and the lower restrictor cause the sealant to flow between at least a portion of the plurality of strands.
18. The apparatus according to claim 17, wherein the sealant comprises suspended particulate, the suspended particulate lodging in flow restrictions within the plurality of strands of the cable.
19. The apparatus according to claim 16, wherein reservoir comprises a first chamber and a second chamber, the first chamber initially having a solvent, the solvent being a fluid that removes grease, and the second chamber initially having the sealant, wherein the solvent is discharged into the axial passage before the sealant is discharged into the axial passage.
20. The apparatus according to claim 16, wherein the reservoir is located in a remotely operated vehicle, the remotely operated vehicle stabbing into a fluid passage in communication with the axial passage.
Type: Application
Filed: Apr 25, 2012
Publication Date: Oct 31, 2013
Applicant: Vetco Gray UK Limited (Aberdeen)
Inventor: Andrew David Hughes (Glasgow)
Application Number: 13/455,574
International Classification: E21B 33/06 (20060101); E21B 33/064 (20060101); E21B 33/035 (20060101); E21B 23/00 (20060101);