The invention relates to well intervention apparatus and to a method of well intervention. The intervention may be carried out on land or sea based oil or gas rigs.
Well interventions are remedial operations that are performed on oil or gas producing wells with the intention of restoring or increasing production. There are three main types of well intervention, namely wireline intervention, coiled tubing intervention and hydraulic work over intervention. The wireline technique involves running a cable into the well from the surface, such as from a platform deck or a vessel. An intervention tool string is attached to the wire and the weight of the tool string, plus additional weighting if necessary, is used to run the wire into the well, where the tool string performs a maintenance or service operation. Wireline intervention is carried out in wells under pressure. The wire is supplied from a drum and passes via two sheaves to a stuffing box which is exposed to well pressure on its well side. Wireline intervention is a light well intervention process.
Coiled tubing intervention is a medium well intervention process, requiring the use of a larger space or deck. It has the advantage over wireline intervention that it provides a hydraulic communication path to the well, but uses heavier and more costly equipment and requires more personnel.
The coiled tubing is a length of continuous tubing supplied on a reel. The outside diameter of the tubing ranges from small sizes of about 3 cm so-called capillary tubing) up to 8 or 9 cm. The tubing is fed from the reel upwardly to a tubing guide, known as a goose neck, and from there via an injector downwardly towards the well.
Coiled tubing is usually manufactured from steel alloy and is much heavier and larger than wireline. An injector head is required to push or “snub” the tubing into the well, and to pull it out of the well when an intervention job has been completed.
Coiled tubing has been used to provide a pathway into a well for both fluid and electrical communication. An electrical cable is loosely carried inside the coiled tubing and the remaining space inside the coiled tubing is used to provide fluid communication. The inventors have recognized that during feeding of the coiled tubing from the reel, the electrical cable may move relative to the inside wall of the coiled tubing, causing frictional wear and tear to the electrical cable. Moreover, given that the coiled tubing may be lowered to depths of hundreds or thousands of meters, relative movement may arise from different elongations of the electrical cable and the coiled tubing under their own weight, again giving rise to wear and tear.
Viewed from a first aspect the invention provides well intervention apparatus comprising a flexible hose to be lowered into a well, a stuffing seal which engages around the hose during lowering, at least one tool provided at a downhole end portion of the hose, and a plurality of individual tubes extending along an inside region of the hose and connecting to the at least one tool, each individual tube providing a fluid path for fluid communication between outside of the well and the at least one tool inside the well, and each individual tube being laterally supported in said inside region such that its lateral movement is restricted.
Viewed from another aspect the invention provides a method of well intervention comprising lowering a flexible hose into a well through a stuffing seal which engages around the hose during lowering, at least one tool being provided at a downhole end portion of the hose, and a plurality of individual tubes extending along an inside region of the hose and connecting to the at least one tool, each individual tube providing a fluid path for fluid communication between outside of the well and the at least one tool inside the well, and each individual tube being laterally supported in said inside region such that its lateral movement is restricted.
By providing laterally supported individual tubes, wear of those tubes during lowering of the hose into the well may be minimized.
The well intervention method may involve carrying out a plurality of operations using the at least one tool. The plurality of operations may include well logging, jetting, drilling or cutting. The plurality of operations can be carried out without having to change from one intervention hose to another, by using the plurality of individual tubes for fluid communication. Thus the apparatus and method can involve the use of a single intervention hose to perform plural intervention operations. The intervention hose may be lowered just once to perform a plurality of operations, and then raised. Even if it is necessary to lower and raise the intervention hose between operations, the rest of the equipment for deploying the intervention hose, such as the stuffing seal and so forth, need not be changed. This can streamline operations and save costs.
At least two, or at least three, or at least four, or at least five, or at least six individual tubes for fluid communication may be provided. Thus one or more individual tubes may be used for an operation such as jetting or cleaning, whilst one or more other individual tubes may be used for another operation such as supplying hydraulic fluid to a hydraulic pump or motor to effect a cutting or drilling operation.
By providing at least three individual tubes, two of them may be used for a particular operation, for example one for fluid to advance downhole and the other for return of fluid, and then a third individual tube is available for use in the event of a problem arising with the first or second tube. Therefore, it would not be necessary to scrap the flexible hose in the event of the first or second tube becoming unusable.
A first individual tube may have a different internal diameter from a second individual tube. A first individual tube may have a smaller internal diameter than the internal diameter of a second individual tube. For example, the first individual tube may be used for supplying hydraulic pressure to operate or control a tool, and the second individual tube may be used for supplying fluid which is discharged into the well. The larger diameter is beneficial in order to minimize flow resistance.
By providing individual tubes for fluid communication, a situation where two separate fluid paths share a common wall can be avoided. Therefore, the effect of pressure inside one individual tube on another individual tube may be minimized.
In addition to individual tubes being provided for fluid communication, one or more individual tubes may also be provided for electrical communication. Such an individual tube may take the form of an electrical cable.
In addition to individual tubes being provided for fluid communication, one or more individual tubes may also be provided for optical communication. Such an individual tube may take the form of a fiber-optic cable.
An embodiment may include individual tubes for fluid communication, electrical communication, and optical communication.
The individual tubes may be sufficiently closely arranged to provide lateral support to each other within the confines of the hose. A flexible material in the inside region may provide said lateral support to the individual tubes. The flexible material may comprise filler members, such as filler tubes or solid tubes. The flexible material may comprise material which is injected into the hose and allowed to set.
The inside region of the hose may be considered as the entire region within an outer sheath of the hose. All of this region may be occupied by individual tubes and other solid material. The other material may comprise flexible material and/or weight bearing material such as steel wires. In these arrangements, no part of the inside region is left as space within the outer sheath. By avoiding such space, entry of fluids, such as liquids or gases, to the inside region (other than intentionally to the insides of the individual tubes) can be avoided or minimized.
The individual tubes may be longitudinally supported in the inside region of the hose such that their longitudinal movement is restricted. This can minimize differential stretching of the individual tubes which may otherwise cause them to wear or break. It will be appreciated that the hose may be hundreds or thousands of meters in length, so that significant tensile forces are involved. The lateral and longitudinal support to the individual tubes may be provided by the same means, which may be a sufficiently close arrangement of the individual tubes to provide lateral and longitudinal support to each other within the confines of the hose, or the means may include flexible material in the inside region to provide lateral and longitudinal support to the individual tubes.
The flexible hose may be of a type usually used as a subsea umbilical. Subsea umbilicals are used for example to operate a subsea blow-out preventer from the surface. The inventors have realized that a subsea umbilical can be lowered into a well to provide plural lines of communication, including fluid communication and preferably also electrical or optical or a combination thereof, between outside of the well and inside the well. Where necessary, a subsea umbilical can be specified to a manufacturer so that it will tolerate the environment inside a well, for example to tolerate heat, pressure, exposure to natural or injected well fluids, exposure to chemicals, and so forth.
The flexible hose may typically have an outside diameter of 20-150 mm, preferably 20-120 mm or 40-120 mm, for example having an outside diameter of 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm or 100 mm.
A seal may be provided around the downhole end portion of the hose. Such a seal can engage with an outer sheath of the hose. One or more O-rings may serve as such a seal. A sealing mechanism may be provided to compress the seal between the outside of the hose and a body extending circumferentially around the hose.
A bottom hole assembly may be provided at the downhole end portion of the hose, the bottom hole assembly having said seal around the downhole end portion of the hose. A termination assembly may be provided. The hose may extend into a body of the termination assembly, and the seal may be provided in a cavity in the body. A sealing mechanism may be provided at least partly in the cavity to compress the seal between the outside of the hose and the body extending circumferentially around the hose. The sealing mechanism may comprise at least one axially movable member, configured so that when the axially movable member moves axially towards the seal, the seal is caused to engage in sealing manner between the outside of the hose and the body.
The inside region of the hose may be open to a chamber in the bottom hole assembly, the chamber being sealed from the outside. Thus the inside region of the hose may be isolated from well pressure. The chamber may be formed in the termination assembly. The chamber may be sealed from above by the seal around the intervention hose. The chamber may be sealed from below by a second seal. The second seal made comprise one or more O-rings.
A connector may be provided in the chamber for connecting a continuation tube to one of the individual tubes, the continuation tube extending to the at least one tool. The connector may be a twin ferrule connector assembly.
The bottom hole assembly may comprise a termination assembly for the intervention hose, the termination assembly being removably connected to the at least one tool.
The well intervention apparatus may comprise at least two tools at the downhole end portion of the hose, a said individual tube providing a fluid path for fluid communication between outside of the well and a first one of said at least two tools, and a said individual tube providing for fluid communication between outside of the well and a second one of said at least two tools. The individual tube for the first tool may connect directly to that tool or it may connect via a continuation fluid conduit. The individual tube for the second tool may connect directly to that tool or it may connect via a continuation fluid conduit.
The well intervention apparatus may comprise at least one individual tube in the form of an electrical cable. The well intervention apparatus may comprise at least one individual tube in the form of a fiber-optic cable.
In many intervention operations, it is expected that the well will be a non-subsea well. By this it is meant that access to the well will not be underwater. Thus, in a preferred well intervention apparatus and method, the stuffing seal will be provided not underwater. The wellhead may be in air, not underwater. In this specification non-subsea wells include an offshore well, with a wellhead which is on a deck (i.e. “dry”), or an onshore well, again with a wellhead which is “dry”.
Certain preferred embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:
The drawings are schematic in nature and where cross-sections are shown some features are omitted for simplicity of explanation.
An intervention hose 2 is provided on a drum 4 supported in a drum housing 6 which sits on the ground or a deck. The drum 4 includes a pulling mechanism, which can also provide a back tension function. The pulling mechanism may be of the type used for wire line drums. The drum 4 also includes a spooling mechanism, as is known for coiled tubing intervention reels.
The intervention hose 2 extends from the drum to a guiding sheave (not shown) rotatably supported on a guiding sheave holder 8 (partially shown), where it is deviated from an upwardly inclined direction to a vertical downward direction, towards a well. The intervention hose 2 extends downwardly from the guiding sheave into an intervention stack 10, which consists of a dual stuffing box 12 and a lubricator 14. The dual stuffing box 12 comprises a plurality of stuffing seals which engage in sealing manner around the intervention hose, to allow the hose to be lowered or raised whilst providing an environment below the dual stuffing box 12 which is sealed from the outside.
A blow-out preventer (BOP) 16 is provided below the intervention stack 10, and a shear seal 18 is provided below the BOP. In this embodiment, in which the intervention is being performed on a subsea well, a flanged connection 20 to a riser 22 is provided below the shear seal 18, and the riser 22 extends vertically downwardly from the surface through the sea to a wellhead (not shown). In an alternative embodiment, where the intervention is being performed on a land-based well, the flanged connection 20 is made directly to a wellhead.
The intervention hose 2 comprises a plurality of individual tubes contained in an outer sheath 34, as can be seen in
The pair of electric cables 36 communicate with the well logging tool 28, the five small-diameter fluid lines 38 communicate with the jetting tool 30, and the intermediate diameter fluid lines 40 and the large diameter fluid line 42 communicate with the drilling tool 32. This arrangement will be further described with reference to
A chamber 46 is provided in the termination assembly 26, and in this chamber the individual tubes emerge from the outer sheath 34 of the intervention hose 2. At the upper end of the chamber 46 a sealing arrangement is provided on the outer sheath in order to seal the chamber from the outside. At the lower end of the chamber 46 another sealing arrangement is provided to seal the chamber from the outside. Further details of the sealing arrangements are described later.
The metal cable 44 also emerges from the outer sheath 34 of the intervention hose 2 into the chamber 46 and is secured at its lower end to the termination assembly 26 by an anchor 48. The individual tubes extend downwardly through the chamber 46 to a set of twin ferrule connector assemblies 50 (see
The other continuation individual tubes of the set 56 in the well logging tool 28, namely continuation individual tubes 38b, 40b and 42b, pass through the well logging tool 28 to another set of twin ferrule connector assemblies 58 at the interface between the well logging tool 28 and the high-pressure jetting tool 30. The twin ferrule connector assemblies 58 form a connection with a set 60 of individual tubes in the jetting tool 30, these individual tubes consisting of continuation individual tubes 38c, 40c and 42c, which provide further continuations respectively of the individual tubes 38, 40 and 42 contained in the intervention hose 2. The continuation individual tubes 38c, 40c and 42c are shown in the section 8-8 of
The other continuation individual tubes of the set 60 in the jetting tool 30, namely tubes 40c and 42c, pass downwardly along the length of the tool to a further set of twin ferrule connector assemblies 64 at the interface between the jetting tool 30 and the drilling tool 32. The twin ferrule connector assemblies 64 form a connection with a set 66 of individual tubes in the drilling tool 32, this set 66 consisting of continuation individual tubes 40d and 42d, which provide further continuations respectively of the individual tubes 40 and 42 contained in the intervention hose 2. The continuation individual tubes 40d and 42d are shown in the section C-C of
The drilling tool 32 is removably connected to the jetting tool 30. If it is desired to modify the bottom hole assembly 24 by omission of the drilling tool 32, it can be disconnected and the continuation individual tubes 40c and 42c could be terminated by appropriate plugs, either at the interface between the jetting tool 30 and the drilling tool 32, or the interface between the well logging tool 28 and the jetting tool 30.
Similarly, the jetting tool 30 is removably connected to the well logging tool 28. Therefore, if it is desired to modify the bottom hole assembly 24 by omission of the jetting tool 30 and the drilling tool 32, the jetting tool 30 may be disconnected from the well logging tool 28. The continuation individual tubes 38b, 40b and 42b could be terminated by appropriate plugs, either at the interface between the well logging tool 28 and the jetting tool 30, or the interface between the termination assembly 26 and the well logging tool 28.
In this embodiment twin ferrule connector assemblies are provided for all the individual tubes in the termination assembly 26, at the interface between the termination assembly 26 and the well logging tool 28, at the interface between the well logging tool 28 and the jetting tool 30, and at the interface between the jetting tool 30 and the drilling tool 32. However, in alternative embodiments an individual tube may extend continuously from the intervention hose 2 through the termination assembly 26 to a tool, without having to form a connection via one or more twin ferrule connector assemblies.
A sealing arrangement is provided on the outer sheath in order to seal the chamber from the outside. The sealing arrangement comprises a pair of O-rings 78 and a pair of ring members 80 which extend round the outer sheath 34 of the intervention hose 2, as seen in further detail in
At the lower end of the chamber 46 another sealing arrangement is provided to seal the chamber from the outside. The upper sleeve 84 terminates in a lower skirt 91, where it is bolted to the feed-through receptacle 52. A top portion of the feed-through receptacle is provided with a pair of O-rings 92, which provide the sealing arrangement at the lower end of the chamber 46 by sealing between the feed-through receptacle 52 and the lower skirt 91 of the upper sleeve 84 of the termination assembly 26.
The termination assembly 26 is connected in removable and sealed manner to the well logging tool 28. A pair of O-rings 94 is provided around the radially outer surface of a lower portion of the feed-through receptacle 52, and each O-ring 94 engages with a radially inner surface of an upper portion of the well logging tool 28. A connecting sleeve 96 on the lower portion of the feed-through receptacle 52 is formed with an internal thread 98 which mates with an external thread on an upper portion of the well logging tool (not shown). During assembly, once the respective twin ferrule connector assemblies at the interface between the termination assembly 26 and the well logging tool 28 are aligned and connected up, the connecting sleeve 96 is rotated relative to the lower portion of the feed-through receptacle 52 to cause the well logging tool 28 to advance upwardly without rotation relative to the termination assembly 26. Once the well logging tool and the termination assembly 26 are tightly engaged, the connecting sleeve 96 is locked in place using screws 98.
In a similar manner to the connection between the termination assembly 26 and the well logging tool 28, the well logging tool 28 is connected in a removable and sealed manner to the jetting tool 30, and the jetting tool 30 is connected in a removable and sealed manner to the drilling tool 32.
Number | Date | Country | Kind |
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1816857.5 | Oct 2018 | GB | national |
This application claims priority to PCT Patent Appln. No. PCT/EP2019/078123 filed Oct. 16, 2019, which claims priority to GB Patent Appln. No. 1816857.5 filed Oct. 16, 2018, which are herein incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/078123 | 10/16/2019 | WO | 00 |