Patent Application
20140102719
The present invention relates to a formation fixation device for securing a tubular in an open-hole wellbore. Furthermore, the invention relates to a downhole fixation system for securing a casing comprising a first end and a second end in an open-hole wellbore and to a method of permanently fixating a tubular part in an open-hole wellbore as well as to use of a formation fixation device according to the invention for fixating a tubular part in an open-hole wellbore.
Wells are completed in a variety of ways; some are made as open-hole completions and some as casing completions. In casing completing, the casing is often cemented in the wellbore. This process is slow and requires a drilling rig at the surface, which is very expensive to use. It is desirable to be able to run in and secure the casing in an open-hole wellbore as fast as possible to reduce costs associated with renting expensive drilling rigs.
An alternative to cemented casings is disclosed in WO 09/120759 which describes a combined “Wellbore anchor and isolation system” comprising a tubular which may be attached to a tool string and lowered into a well. The tubular is provided with an anchor system comprising telescopic pistons which are extended in a radial direction by applying hydraulic pressure from within. Each of the telescopic pistons is comprised by three rings movable in relation to one another. An isolation element is disposed on the outside of the tubular, creating an isolated zone when engaged with the walls of a wellbore.
When a casing has been positioned in an open-hole wellbore, it is sometimes important that it does not move and that the exact position is maintained. This is especially important when annular barriers are used to seal off a section of the wellbore. If the casing is moved following the deployment of the annular barriers, the sealing characteristics of the annular barriers may be compromised. The deployment of the annular barriers may in itself contribute to a movement of the casing in the well.
It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved formation fixation device, system and method for securing casing in an open-hole wellbore downhole.
The above objects, together with numerous other objects, advantages, and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a permanent formation fixation device for securing a tubular in an open-hole wellbore, the formation fixation device comprising:
An advantage in this respect is that the casing may be rapidly secured in an open-hole wellbore during construction of an oil or gas well just by pressurising the casing from within e.g. by means of a drill pipe. This reduces the time required to complete the well and thereby reduces the days in which an expensive drilling rig is needed. Further, it may be possible to secure the casing in the wellbore and deploy the annular barriers as part of the same working procedure and substantially simultaneously.
In an embodiment of the invention, the fixation unit may comprise a locking mechanism for permanently locking the fixation unit in the projected position.
An advantage in this respect is that the fixation unit does not collapse when the tubular part is no longer pressurised.
Furthermore, the fixation unit may comprise a slotted liner having a plurality of members connecting the first end and the second end, the members being projected in a radial direction in relation to the tubular part when the ends of the fixation unit are moved towards each other.
This creates a simple and reliable construction with a plurality of members engaging the formation.
The slotted liner may surround the tubular part.
Moreover, each of the members may have a bend initiator, such as a transverse slot or fold, arranged substantially in a middle part of each member in the axial direction.
By having a bend initiator, a bend point of the members may be controlled and the bend initiated, thereby decreasing the amount of force used for initial bending.
Furthermore, the fixation unit may comprise two pivotally connected members.
Additionally, the fixation unit may be arranged in a recess in the tubular part.
An advantage in this respect is that the use of a fixation unit in combination with a casing does not affect the outer diameter of the casing.
Also, the fixation unit may be arranged on the outside of the tubular part.
In addition, the fixation unit may be connected with the exterior surface of the tubular part.
Moreover, the fixation unit may be arranged partly inside the tubular part and extend through a slot in the exterior surface.
In an embodiment, one of the ends of the fixation unit may constitute a piston part comprising a surface adapted for receiving a force induced by a pressurised medium contained in the hollow interior of the tubular part.
In another embodiment, both ends of the fixation unit may constitute a piston part comprising a surface adapted for receiving a force induced by a pressurised medium contained in the hollow interior of the tubular.
Moreover, one of the ends of the fixation unit may be fixed in relation to the tubular part.
In addition, both ends of the fixation unit may be movable in relation to the tubular part.
This may reduce the axial movement of the device during activation of the fixation unit and facilitate the engagement of the fixation unit with the formation.
In an embodiment, the formation fixation device may comprise a plurality of fixation units.
The plurality of fixation units may be distributed around a periphery of the tubular part.
Moreover, the plurality of fixation units may be distributed along the axial direction of the tubular part. Hereby the formation fixation device is aligned inside the wellbore.
Furthermore, the plurality of piston parts may be distributed around a periphery of the tubular.
Additionally, the plurality of piston parts may move one end of the fixation unit, e.g. the slotted liner.
Also, the plurality of fixation units distributed along the axial direction of the tubular part may be displaced relative to one another around the periphery of the tubular part.
In addition, the plurality of fixation units may be evenly distributed in the axial direction and around the periphery of the tubular part.
The present invention furthermore relates to a downhole fixation system for securing a casing comprising a first end and a second end in an open-hole wellbore, the fixation system comprising:
In an embodiment, the pressure creating device may be a downhole tool adapted to be arranged in fluid connection with the fluid passage.
Furthermore, the pressure creating device may be a pump positioned on the outside of the wellbore.
Moreover, the pressure creating device may be connected with one end of a drill pipe and another end of the drill pipe may be connected with a connecting unit which is sealingly connectable with the first end of the casing, and the second end of the casing being sealed.
In addition, sealing means, such as packers, may be arranged around the drill pipe on opposite sides of the fluid passage, whereby a defined section of the casing may be pressurised.
Also, the invention relates to a method of permanently fixating a tubular part in an open-hole wellbore, the method comprising the steps of:
Finally, the present invention relates to use of a formation fixation device as described above for fixating a tubular part in an open-hole wellbore
The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which
a shows a view of a formation fixation device in an unset condition according to the invention,
b shows a view of the formation fixation device shown in
a shows one embodiment of a formation fixation device comprising a slotted liner,
b shows a cross-sectional view across line a-a of the formation fixation device shown in
c shows a view of a member having a bend initiator,
a shows a view of a locking mechanism,
b shows another embodiment of the locking mechanism,
a shows a schematic drawing of an open-hole wellbore with the permanent formation fixation device arranged in connection with other casing elements and a pressure creating device deployed in the well, and
b shows a schematic drawing of an open-hole wellbore with an alternative pressure creating device deployed in the well.
All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.
a and 1b show a formation fixation device 1 for positioning in an uncased wellbore.
When the formation fixation device 1 is in the relaxed position, the fixation units 20 can be activated, whereby the fixation unit 20 projects in the radial direction in relation to the tubular part 10. When the fixation unit 20 is projected so that the fixation units are fastened or anchored in the wall of the wellbore, i.e. the formation, the formation fixation device 1 is said to be in an activated or set condition, as shown in
Each fixation unit 20 comprises a first end 21 and a second end 22 movable in relation to one another in an axial direction of the tubular part 10 when the tubular part is pressurised from within. During activation of the formation fixation device 1, the fixation units 20 are projected by moving the first end 21 a distance “d” towards the second end 22 which is fixed relative to the tubular part 10. As an alternative to the embodiments shown in
In
As shown in
In
The tubular part 10 extends in the entire length of the formation fixation device 1, as indicated by the axial dotted lines shown in
The interior 28 of the protrusion 27, wherein the piston part 30 of first end 21 of the fixation unit 20 is arranged, constitutes a fluid passage 28 between the hollow interior 29 of the tubular part 10 and the piston part 30 of the first end 21. When the formation fixation device 1 is activated by pressurising a fluid in the interior of the tubular part 10, the fluid is pushed through the fluid passage 28, thereby exerting a force on a surface 40 of the piston part 30. This force is directed into the members 23, whereby the members 23 is forced to project and the fixation unit 20 enters into the set position when the members press against and partly into the wall of the borehole.
a and 5b show a close-up of the first end 21 of the fixation unit 20. The first end 21 is positioned in the interior 28 of the protrusions 27, and seals 42 are arranged in grooves in the outer surface of the piston part 30 between the first end 21 and the inner surfaces of the interior 28. The seals 42 create a fluid-tight connection and prevent the fluid inside the hollow interior 29 from flowing into the annulus surrounding of the formation fixation device 1 when the tubular is pressurised from within and prevent the formation fluid from flowing into the tubular part 10 when the tubular part is no longer pressurised. In the solution shown in
The fixation unit 20 further comprises a locking mechanism 50 for fixating the fixation unit 20 in the projected and set position when the formation fixation device 1 has been activated.
a shows a locking mechanism 50. The exterior surface 11 of the tubular part 10 is serrated, threaded or toothed thereby forming a plurality of studs 51 and intermediate grooves. The studs 51 are configured for engagement with a tooth 52 positioned on the piston part 30. As the piston part 30 is moved towards the surface 41, the tooth 52 shifts from engagement with one stud 51 to engagement with the subsequent stud 51 until the fixation unit 20 has reached its set position.
The locking mechanism 50 shown in
In the solution shown in
It will be evident for a person skilled in the art that such a locking mechanism 50 may be designed in a number of other ways, e.g. as a mechanical locking mechanism, an electro-mechanical locking mechanism, etc.
In the solution shown in
The bend initiators 24 are arranged substantially in the middle part of the fixation unit 20, as described above, but also adjacent to the ends 21, 22 of the fixation unit 20. The bend initiators 24 are formed as indentations, but may also be slots or folds. By having bend initiators 24, the bending of the members 23 is controlled to occur at the position of the bend initiators and the force required to initiate the bending is substantially reduced.
It will be evident for a person skilled in the art that several other solutions may be conceived by combining the above described embodiments. For example, a pivotally mounted piston part 30 may be used in combination with the slotted liner 26. The piston part 30 in the solution shown in
Having described the structural features, the functionality and use will be described in further detail below.
Starting from the unset condition, e.g. as shown in
The hollow interior 29 may be pressurised by injecting a fluid, such as a fluid present in oil or gas wells downhole, drilling fluid or any other fluid supplied from the surface of the well. When a fluid is injected and pressurised, it flows into the fluid passage 28 and exerts a force on the surface 40 of the fixation unit 20. The magnitude of the force exerted on the piston part 30 depends on the surface area of the surface 40 and the pressure of the fluid inside the formation fixation device 1. To project the fixation unit 20, the force exerted on the surface 40 must exceed the force exerted on the fixation unit 20 by the formation pressure in the annulus 70 surrounding the formation fixation device 1. The force exerted on the surface 40 must also be sufficient for members 23, 31a, 31b to penetrate the formation.
In
As the piston part 30 moves, the fixation unit 20 is gradually projected radially. When the fixation unit 20 hits the walls or formation of the wellbore, it will gradually dig into the formation and anchor the formation fixation device 1. Depending on the characteristics of the formation, the fixation unit 20 will dig more or less into the formation. The projection of the fixation unit 20 stops when the force exerted on the fixation unit 20 by for example formation sand or rock exceeds the force exerted by the pressurised fluid inside the formation fixation device 1. Alternatively, the projection stops when the piston part 30 abuts the surface 41.
The formation fixation device 1 may be used either alone or in combination with any device or structure to be secured in an open-hole wellbore. Now referring to
a, the formation fixation device 1 is used in combination with casing elements 64 and one or more annular barriers 63 in a casing assembly 80 or casing string. Casing elements 64, annular barriers 63 and one or more formation fixation devices 1 are assembled into a casing string at the surface, e.g. by screwing them together, and are lowered into the wellbore. When the formation fixation device 1 is used in combination with an annular barrier 63, the formation fixation device 1 is positioned right next to the annular barrier. This is done to secure in the best possible way that the position of the annular barrier 63 is fixed in the wellbore by the formation fixation device 1. The formation fixation device may also be used when fixating a liner hanger.
When in the desired position, one or more formation fixation devices 1 is/are activated to secure the casing assembly 80 in the wellbore. When activated, the fixation units 20 of the one or more formation fixation devices 1 project radially and engage with the walls of the wellbore. Depending on the material composition of the formation surrounding the wellbore, the degree of penetration of the fixation units 20 of the walls varies. This way, the fixation units 20 secure the formation fixation device 1 and attached casing elements 64 in the wellbore. Aside from securing the casing, the formation fixation device 1 contributes to centralising the casing elements 64 in the wellbore.
The one or more formation fixation devices 1 may be activated by injecting a fluid in a number of different ways. The fluid may be injected locally in a defined section of the casing assembly 80 comprising one or more fluid passages 28. Local injection may be conducted by lowering a drill pipe 60 with circumferential packers into the casing assembly 80 and positioning the packers 61 on opposite sides of the one or more fluid passages 28. By injecting a fluid through the drill pipe 60 and into the hollow interior 29 between the packers 61, the fixation device 1 is pressurised and activated. Local injection may alternatively be done by a well tool comprising a pump. Such a tool may be lowered into the casing assembly 80 and connected directly to the fluid passage 28. The well tool may inject fluid already present in the well or fluid carried by the tool into the fluid passage 28.
As an alternative to local injection, the entire casing assembly 80 may be pressurised, as illustrated in
The formation fixation device 1 may be a permanent fixation device. By permanent is meant that the projection of the fixation unit 20 cannot be reversed without destroying the functionality of the formation fixation device 1. The formation fixation device 1 can thus not be reused after having been activated or set for the first time. When the formation fixation device 1 has been activated and the fixation unit 20 has dug into the formation, the fixation unit is locked in the set position. When the fixation unit 20 has been set and the formation fixation device 1 is in the activated condition, the pressure inside the formation fixation device does not have to be sustained. The formation fixation device 1 is permanently locked in the activated condition.
By fluid or well fluid is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By a casing is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.
Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10195570.6 | Dec 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/073100 | 12/16/2011 | WO | 00 | 7/30/2013 |
