Patent Application
20060151174
The invention is related to a device designed to permit the flow of a fluid through a production tube in an oil well or the like.
Such devices may be used in a well to optimize production or injection of fluids from or into the well as a function of time. It is particularly applicable to wells in which the fluid enters the well at a number of different locations along its length.
Various implementations of flow control devices or valves have already been proposed in the domain of oil wells or the like.
One such device is described in document FR-A-2 790 509, comprises holes formed in a production tube, and a closure sleeve installed on the outside of the production tube and free to slide in front of each hole formed so as to control the flow therethrough. In this manner, the fluid flow passing through the production tube is adjusted by controlling the closure sleeve which allows only a limited amount of fluid to pass therethrough either from the underground formation to the surface, or vice versa, depending on the exact function of the well.
However, one major problem with this type of flow control device is that of erosion of the tube around the holes due to the presence of solids (sand) in the produced fluids, to the extent that the valve can lose the ability to control flow effectively and ultimately to fail completely.
Although the entire production tube may be degraded due to wear caused by passage of the fluid, certain localized parts are subject to more severe wear and deterioration. In particular, this is the case at the contours around holes through which fluid passes, which are subject to wear and damage causing a malfunction of the flow control device. Wear of these contours by erosion may be harmful for the precision of the control device, since these imprecisions can make it possible for flow variations to arise independently of variations caused by control of the relative position of the closing sleeve and the passage holes.
In order to overcome this problem, it has been proposed to create a protective envelope extending all around the outer surface of the portion of the production tube comprising holes for passage of fluid, in order to increase the life of this portion of the tube and at the same time to reduce the inaccuracies caused by wear due to erosion.
Although the technological solution proposed and mentioned above has led to relative improvements to the life of the portion of the production tube provided with the protective envelope, it was quickly realized that this technique provided insufficient protection for a device with suitable resistance to wear by erosion. The simple fact of providing a protective envelope around the outer surface of the portion of the production tube does not provide any protection against wear by erosion of the inner surface of the fluid passage holes. Experiments carried out have shown that this weakness can also cause equipment deterioration due to erosion, and thus encourage the appearance of inaccuracies in the fluid flow control.
Thus, to overcome this disadvantage, an insert solution was presented consisting of inserting a ring with high resistance to wear by erosion, inside each of the cylindrical passage holes. In this solution, the ring only extends partially into the passage hole, but it preferably extends sufficiently to protect the entire inner surface of the hole. In particular, this technique is described in document FR-A-2 790 509, in which the device comprises ceramic rings at the entry to each passage hole in order to reduce wear by erosion caused by circulation of the fluid not only around the contours of the passage holes, but also around part of the inner surface of these passage holes.
The protective ceramic rings on the inside of the cylindrical shaped passage holes can easily be inserted due to the geometry of the different elements used. Nevertheless, force fitting of this assembly is not easy for all types of protection inserts, and particularly for inserts with a complex geometrical shape. The shape of passage holes of devices for control of the flow through a production tube placed at the bottom of an oil well is very variable, and is in no way limited to a simple cylindrical shape. Consequently, when the shapes of passage holes are complex, techniques known in prior art do not propose any high performance means of protecting the inside of fluid passage holes against wear by erosion.
The present invention provides a device for control of the flow through a production tube placed in an oil well, at least partially overcoming the disadvantages with embodiments according to prior art mentioned above.
More precisely, the invention provides a flow control device in which the portion of the production tube is provided with means of protection against wear by erosion acting not only around the contours of the openings but also at the inner surface of the openings, the protection means easily being adapted to the portion of the tube regardless of the required geometric shape of these openings.
A device according to the invention comprises a portion of the production tube provided with through orifices and means of providing the device with resistance to wear by erosion, the device also comprising a sliding sleeve that can be controlled to adjust the flow. According to the invention, the protection means comprise several add-on sectors assembled around the portion of the tube, each add-on sector being provided with an associated inner stiffener penetrating into the portion of the production tube through at least one through orifice, at least one of the add-on sectors being provided with at least one opening extending through the sector and its associated inner stiffener.
Advantageously, the control device according to the invention is provided with very high performance means of protection against wear by erosion, to the extent that the contours of the openings through which the fluid circulates are composed of protective add-on sectors, and also due to the presence of inner stiffeners matching the inner surface of through orifices formed on the portion of the production tube, consequently preventing contact between the fluid and these through orifices.
The ease of assembly of the protection means on the portion of the tube can be entirely independent of the geometric shape of the openings, unlike embodiments according to prior art. The inner stiffeners housed on the inside of the through orifices can be fixed to the add-on sectors, themselves assembled around the portion of the production tube. In this way, the technological solution adopted would not require any force fitting of the inner stiffeners into the through orifices, since these stiffeners are held in place by the attachment of the sectors onto the outer surface of the portion of the tube.
The openings through which the fluid passes can then be formed through add-on protection sectors and their associated inner stiffeners, and no longer in the portion of the production tube. This specific characteristic provides the possibility of choosing a very wide variety of opening shapes, without any constraints with regard to the fixation of the anti-erosion protection on the portion of the production tube.
Another advantage of the device according to the invention relates to the possibility of simply and quickly modifying the shape of openings, by replacing the add-on sectors by other sectors with different opening shapes, without making any modification to the through orifices in the portion of the production tube formed initially.
The protection against wear by erosion achieved by using protection means can be just as efficient when the fluid flows from the surface towards the bottom of the well as when the fluid flows from the bottom of the well to the surface.
Preferably, the add-on sectors form a protective envelope around the outer surface of the portion of the production tube to prevent any contact between the portion of the production tube and the fluid causing wear by erosion, to further increase protection of the outer surface of the portion of the tube and more particularly the contours of the openings.
Furthermore, the use of two clamping rings around the portion of the production tube to fix the add-on sectors onto the portion of the production tube can facilitate assembly and disassembly of such a device. In order to cooperate with these clamping rings, each add-on sector may comprise an upper groove and a lower groove located at its upper end and its lower end respectively. In this case, the upper groove and lower groove are then capable of being fitted with an upper clamping ring and a lower clamping ring respectively.
Preferably, the sliding sleeve is capable of sliding on the add-on sectors in order to close off several openings that may be of different shapes, in the required manner.
Each add-on sector and its associated inner stiffener can be superposed and each can have approximately the shape of an annular portion, particularly to facilitate cooperation of the add-on sectors with the sliding closing sleeve. Furthermore, the shape of the inner stiffener of each add-on sector matches the shape of the through orifice in which it is located, so as to obtain a continuous internal surface of the portion of the production tube.
According to a preferred embodiment of this invention, the inner stiffener of each add-on sector is provided with a seal that fits on the internal wall of the through orifice in which it is located. In this manner, fluid cannot pass between the through orifices and the inner stiffeners, which has the effect of significantly increasing the precision of the flow control, and eliminating any pressure loss between these different elements. Furthermore, the seals provided enable the add-on sectors to be firmly fixed in the through orifices, considerably reducing vibrations of these sectors, and shocks between the sectors and the inner surface of the through orifices.
Preferably, each add-on sector is made from tungsten or a ceramic.
It is possible that the device will include several sets of sectors each with different openings.
Other advantages and characteristics of the invention will become clear in the non-limitative description given below.
This description will be made with reference to the attached drawings among which:
a and 3b show perspective views taken from different angles of an add-on sector fitted with its associated inner stiffener, used in the flow control device shown in
a and 4b show perspective views taken from different angles, of an add-on sector provided with its associated inner stiffener, according to another preferred embodiment.
The walls of the well 1 are reinforced by a casing 2. In the region of the well shown in
To enable the fluid to be transferred to the surface, a production tube 6 is inserted coaxially over the full height of the well 1. The protection tube 6 is composed of a number of tube segments connected end to end. Part of the flow control device 10 is made on a portion 8 of one of these production tube segments 6. Furthermore, in the rest of this description, the segment on which the flow control device 10 is located will in general be called the “production tube 6”.
The production tube 6 defines a duct 12 on the inside, through which the fluid rises to the surface. The annular space 14 delimited between the casing 2 and the production tube 6 is closed, on each side of the flow control device 10, by annular sealing systems (packers, not shown). Thus, the only way in which the fluid from the natural deposit that passes through the perforations 14 into the well 1 can rise to the surface through the central duct 12 is to pass through the flow control device 10.
The device 10 comprises at least one opening 16 at the portion 8 of the production tube 6 (several of these openings are shown diagrammatically in
The closing sliding sleeve 18 is installed on the production tube 6, so as to be able to move along a direction parallel to the axis of the production tube 6 shown by the arrow F. In this way, the closing sleeve 18 can occupy a low or front position shown in
As can be seen in
The design of the closing sleeve 18, and the design of the various means that have been described above and that enable its operation, can be adapted as a function of conditions encountered. The different elements described are simply presented as examples of particular embodiments.
According to the invention and with reference to
Protection means 32, 34 on portion 8 of the tube 6 are assembled using the upper clamping ring 36, and the lower clamping ring 38 placed around portion 8 respectively, each of them cooperating with the add-on sectors 32. Each add-on sector 32 is preferably provided with an upper groove 40 in which the upper clamping ring 36 can be housed, together with a lower groove 42 in which the lower clamping ring 38 may be housed. To obtain a good quality assembly, the upper groove 40 and the lower groove 42 are located at the upper and lower ends respectively of the add-on sectors 32. (Note that the “upper and lower ends of the add-on sectors 32” refers to the end of each add-on sector 32 closest to the top and closest to the bottom of the well 1 respectively, when these sectors 32 are assembled on the portion 8 of the production tube 6.) Consequently, the selected assembly technique enables a large diversity in the choice of the geometric shape of the openings 16, to the extent that the associated inner stiffeners 34 in which these openings 16 are formed must not necessarily be force fitted into the orifices 30. The associated inner stiffeners 34 are held in place on the portion 8 by means of the attachment of the add-on sectors 32 around this portion 8, without it being necessary to use rigid links between these stiffeners 34 and the through orifices 30. Furthermore, as an example, the associated inner stiffeners 34 will preferably be free to slide in the orifices 30 easily as they are put into place. With this arrangement, it is then possible to require that each add-on sector 32 should comprise several openings 16 with different shapes such as cylindrical or an approximately parallelepiped shape. Thus, regardless of the shape of these openings 16, there is the same ease of fixing protection means 32, 34 on portion 8 of tube 6, this facility being obtained by means of clamping rings 36, 38.
For example,
Also as an example,
Thus, the flow control device 10 may include several sets of add-on sectors 32, each set having different shape openings corresponding to a given flow variation mode. Consequently, depending on the needs encountered, operators can choose the most appropriate set of sectors 32 for the required flow variation through the production tube 6, without worrying about the ease of attachment of the protection means 32, 34 that is always identical. Preferably, the add-on sectors 32 in each set of add-on sectors 32 all have the same opening(s) 16.
As can be seen in
Apart from the matching shapes as mentioned above, in one preferred embodiment of the invention, the inner stiffener 34 of each add-on sector 32 is provided with a seal (not shown) designed to come into contact with the internal wall of the through orifice 30 in which it is located.
The protection means 32, 34, consisting of the add-on sectors 32 and their associated inner stiffeners 34, are preferably made from a material such as tungsten or ceramic, or any other hard material with high resistance to wear by erosion. It is then possible to make an add-on sector 32 and its associated inner stiffener 34 in a single piece, and machining operations are carried out on this piece to make the openings 16.
Obviously, those skilled in the art could make various modifications to the flow control device 10 that has just been described as a non-restrictive example only.
| Number | Date | Country | Kind |
|---|---|---|---|
| 02/12590 | Oct 2002 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP03/11250 | 10/9/2003 | WO | 12/19/2005 |
