The present invention relates to a well tool device comprising a force distribution device.
Well tool devices used in oil and/or gas wells, such as different types of plugging devices (bridge plugs, packers etc) typically comprises a sealing element provided circumferentially around a mandrel device. On each side (i.e. on the upper side and on the lower side) of the sealing element, supporting devices are provided. The well tool device may be configured to be in a run state (a radially retracted state) and a set state (a radially expanded state). The run state is used when running the well tool device into the well. In the set state, a relative axial movement between the supporting devices is causing the sealing element to be compressed axially and hence to expand radially until the outer surface of the sealing element is in contact with the inner surface of the well pipe. Hence, a seal is provided in the annular space between the inner surface of the well pipe and the mandrel device and fluid flow between the lower side of the seal and the upper side of the seal is prevented.
In the set state, the well tool device is designed to withstand a pressure difference between the lower side of the sealing element and the upper side of the sealing element.
The well tool device typically also comprises a ratchet mechanism in order to allow axial movement of at least one of the supporting device in one (a forward) direction (i.e. to move the sealing element from the run state to the set state) but to prevent movement of the at least one supporting device in the opposite (a reverse) direction (i.e. to prevent radial retraction of the sealing element).
There are some disadvantages with these prior art well tool devices.
First, if the well tool device is set in the well at a high temperature, a decrease in temperature may cause the sealing element to shrink. In such a situation, there is a risk that the sealing element may not withstand the same pressure difference as before the temperature decrease.
Second, when the well tool device has been set, the pressure below the sealing element will often increase to a pressure being higher than the pressure above the sealing element, since fluid flow is prevented by the sealing element. This pressure difference will apply a force to the well tool device which is contributing to a compression of the sealing element via the supporting devices. However, if the fluid pressure changes, for example if the pressure above the sealing element gets equal to, or higher than the pressure below the sealing element, there is a risk that the compression force applied by the supporting device onto the sealing element will be reduced.
Third, the ratchet mechanism will allow some movement also in the reverse direction, typically a length up to one teeth length. This reverse movement is often referred to as the “backlash” of the ratchet mechanism.
Hence, in these situations, there is a risk that the sealing element will not be in sufficient contact with the inner surface of the well pipe anymore. Consequently, the well tool device is no longer working as intended.
The above situations may occur in particular in injection wells, where the well tool is cooled down by the injected fluid and where the differential pressure over the sealing element will change before, during and after the injection operation, for example when a safety valve is maintained or tested, etc. Also well tools used in acidizing operations, fracking operations etc may be subjected to the abovementioned temperature/pressure conditions.
In prior art, these effects may be at least partially compensated for by means of relatively long springs (spiral springs or cup springs) applying an axial force onto the supporting devices towards the sealing element. The disadvantage with this solution is that it does not always work sufficiently. Moreover, this solution will increase the length of the well tool device considerably.
Moreover, as coiled springs only give a relatively small force, cup springs must be used in many such tools. The cup springs must often be hardened to achieve satisfying material properties, and if the well tool is to be NACE approved (National Association of Corrosion Engineers), only a few materials can be used, such as UNS N07750, UNS R30003, and UNS R30035. These materials are very expensive. For some applications, the well tool device will need a cup spring with a total length of 150-200 mm and will comprise ca 30 cups/discs.
One or more embodiments of the invention provide a well tool device where the above situations are addressed.
Moreover, many such well tool devices are relatively long, which contributes to a higher material cost and a higher manufacturing cost (machining, milling etc). Hence, one or more embodiments of the present invention reduce the length of such well tool devices. A reduction of length will also make the handling of the tools easier, and possibly also the transportation costs may be reduced.
One or more embodiments of the invention reduce the length of the cup spring and hence reduce the length and costs for the well tool device.
One or more embodiments of the present invention relate to a well tool device, comprising:
where the well tool device may be configured between a run state, in which the sealing element is radially retracted, and a set state, in which the sealing element is radially expanded.
One or more embodiments of the invention may be characterized in that the well tool device further comprises a pressure distribution device for distributing the pressure on the sealing element in the set state via the upper and lower supporting devices, where the pressure distribution device comprises:
a sleeve device provided radially outside the mandrel device and radially inside the sealing element, where the sleeve device is axially displaceable in a sleeve compartment in relation to the mandrel device and the sealing element;
where the sleeve device comprises an upper protrusion for applying a downwardly directed axial force to the upper supporting device when the sleeve device is in its lower position;
where the sleeve device comprises a lower protrusion for applying an upwardly directed axial force to the lower supporting device when the sleeve device is in its upper position;
where a first sealing device is provided radially between the inner surface of the sleeve device and the outer surface of the mandrel device.
The purpose of the pressure distribution device is to distribute the pressure or force applied to the upper and/or lower supporting devices in an improved way and hence to avoid the above-mentioned disadvantages. This is achieved as defined in claim 1 by applying a downwardly directed axial force to the upper supporting device in some situations and by applying a downwardly directed axial force to the upper supporting device in other situations. Hence, the pressure distribution device may also be referred to as a pressure and/or force transmitting device.
In one aspect, the device comprises an upper spring device provided axially between the upper housing device and the upper supporting device.
In one aspect, the upper spring device is provided axially between the upper supporting device and the upper protrusion.
In one aspect, the upper housing device is connected to the upper supporting device by means of an upper connection device, where the upper connection device is configured to allow an axial displacement between the upper supporting device and the upper housing device.
In one aspect, the upper housing device comprises a downwardly protruding ring forming the sleeve compartment, where the downwardly protruding ring has an inner diameter larger than the outer diameter of the upper protrusion of the sleeve device.
In one aspect, the well tool device comprises a lower spring device provided axially between the lower housing device and the lower supporting device.
In one aspect, the lower spring device is provided axially between the lower supporting device and the lower protrusion.
In one aspect, the lower housing device is connected to the lower supporting device by means of a lower connection device, where the lower connection device is configured to allow an axial displacement between the lower supporting device and the lower housing device.
In one aspect, the lower housing device comprises a upwardly protruding ring forming the sleeve compartment, where the upwardly protruding ring has an inner diameter larger than the outer diameter of the lower protrusion of the sleeve device.
In one aspect, the upper and lower protrusions are protruding in a radial direction out from the sleeve device.
In one aspect, the second sealing device is provided radially between the upper supporting device and the sliding surface.
In one aspect, a third sealing device is provided radially between the lower supporting device and the sliding surface.
The above well tool may be a plugging device, a bridge plug, a packer, a straddle, a production packer etc.
Embodiments of the invention will now be described with reference to the enclosed drawings, where
In the following description, the term “upper side” or similar is meant to describe the side of the drawings which are closest to the top side of the well, while the term “lower side” or similar is meant to describe the side of the drawings which are closest to the bottom of the well.
It is now referred to
The well tool device 1 comprises a mandrel device 10 with a through bore 11. The mandrel device 10 is typically cylindrical.
The well tool device further comprises a sealing element 12 provided radially around the mandrel device 10, i.e. the sealing element 12 is provided circumferentially around the mandrel device 10. On the upper side (on the left side in
In
It is now referred to
Also in
In
In one or more embodiments, the upper and lower supporting devices 13, 14 and the upper and lower housing devices 15, 16 are movable in an axial direction in relation to the mandrel device 10. However, in one or more alternative embodiments, one of the housing devices may be fixed to the mandrel device 10.
In
The well tool device 1 further comprises a pressure distribution device 20, for distributing the pressure on the sealing element 12 in the set state via the upper and lower supporting devices 13, 14. More specifically, the pressure distribution device 20 is distributing or transmitting the differential fluid pressure over the sealing element 12 in the set state via the upper and lower supporting devices 13, 14 further to the sealing element 12. The function of the pressure distribution device 20 will be described further in detail below.
In
In the set state, the sealing element 12 is sealing towards the inner surface of the well pipe WP and is also sealing towards the sleeve device 21. A first sealing device 41 is provided radially between the inner surface 25 of the sleeve device 20 and the outer surface of the mandrel device 10, i.e. the first sealing device 41 is provided circumferentially outside the mandrel device 10 and circumferentially inside the sleeve device 21. The purpose of the first sealing device 41 is to prevent fluid flow between the mandrel device 10 and the sleeve device 21.
In
The sleeve device 21 further comprises an upper protrusion 22 protruding in a radial direction out from the sleeve device 21 and a lower protrusion 23 protruding in a radial direction out from the sleeve device 21. The upper and lower protrusions 22, 23 may be provided as continuous flanges circumferentially outside the sleeve device 21, as indicated in
The sleeve compartment 40 has a length L40 which is considerably longer than the length L21 of the sleeve device 21, as indicated in
The sleeve device 21 is axially displaceable in a sleeve compartment 40 in relation to the mandrel device 10 and the sealing element 12. It should be noted that the sealing element 12 and the first sealing device 41 will provide friction and hence at least some pressure must be applied to the sleeve device 21 in order to displace it axially in relation to the sealing element 12 and mandrel device 10.
In
A second sealing device 42 may be provided radially between the upper supporting device 13 and the outer surface 24. A third sealing device 43 may be provided radially between the lower supporting device 14 and the sliding surface 23. The first, second and third sealing devices 41, 42, 43 may be O-rings or other types of sealing devices.
The upper housing device 15 comprises a downwardly protruding ring 15a, having an inner diameter larger than the outer diameter of the upper protrusion 22 of the sleeve device 21. Hence, the protruding ring 15a forms a “cup”, where the space inside the cup forms the upper part of the sleeve compartment 40.
The downwardly protruding ring 15a is also illustrated in
In similar way, the lower housing device 15 comprises an upwardly protruding ring 16a, having an inner diameter larger than the outer diameter of the lower protrusion 23 of the sleeve device 21. Hence, the protruding ring 16a forms a “cup”, where the space inside the cup forms the lower part of the sleeve compartment 40.
In one or more embodiments, the upper and lower supporting devices 13, 14 are connected to the outer surface of the protruding rings 15a, 16a by means of connection devices 18, 19 respectively. The connection devices 18, 19 are causing the respective housing devices to be connected to their adjacent supporting devices. The connection devices are flexible connection devices allowing a limited axial movement between the supporting device and the housing device. In one or more embodiments, the connection device 18, 19 may be a flexible bolt connection in the form of a slotted tension pin, machined pins, dowel pins, hollow dowel pins, spring (slotted) dowel pins etc. inserted through an opening 18a of the supporting device 13 (indicated in
It should be noted that the upper housing device 15 shown in
It should be noted that the connection devices 18, 19 may comprise threaded connection devices allowing a limited axial movement between the respective supporting devices and housing devices, for example threaded connection devices where the threads are spaced apart to allow such movement. In
In similar way, the well tool device 1 further comprises a lower spring device 32 provided axially between the upwardly protruding ring 16a and the lower supporting device 14. As shown in
A compartment 31a for the upper spring device 31 is indicated radially inside the upper supporting device 13 in
It should be noted that the cup springs 31, 32 in
It is now referred to
As shown, the sleeve compartment 40 has a length L40 in the set state that is shorter than the length L40 in the run state. In one or more embodiments, the length L40 of the sleeve compartment 40 in the set state is almost twice the length L21 of the sleeve device 21.
It should be noted that if the bore 11 is a through bore, fluid may flow inside the mandrel device 10. Such well tool devices are often referred to as packers. If the bore 11 is terminated, the well tool device is often referred to as bridge plugs. The well tool device 1 could also comprise an opening and/or closing mechanism provided in the bore 11, in order to allow the bore 11 to go from an open state to a closed state or to go from a closed state to an open state. The opening and/or closing mechanism can be a valve device, a fragile glass disc etc.
In
In
Moreover, it should be noted that the well tool device 1 may be used in many different types of well tools, such as those mentioned in the introduction and in the above description. Hence, the well tool device 1 may comprise several components/elements not described in detail herein, such as anchoring devices for anchoring the tool to the inner surface of the well bore before the sealing element is brought to its set state, connection interfaces for setting tools, retrieval tools etc.
Some situations will now be described for the well tool device 1.
In
In
In
In
In a similar way, the spring devices 31, 32 may prevent smaller undesired movement of the supporting devices 13, 14 such as the backlash movement of the ratchet mechanism described in the introduction.
According to the above, in “normal” situations, the axial compression forces applied from the upper and lower housing devices 15, 16 to the upper and lower supporting devices 13, 14 will provide a sufficient axial compression and hence a sufficient radial expansion of the sealing element 12. However, the sleeve device 21 will, via the upper protrusion 22, applying a downwardly directed axial force to the upper supporting device 14 when the sleeve device 21 is in its lower position. Moreover, the sleeve device 21 will, via the lower protrusion 23, apply an upwardly directed axial force to the lower supporting device 15 when the sleeve device 21 is in its upper position.
A prototype of one or more embodiments described above has been tested and found to fulfill the requirement of ISO14310 Grade V0, i.e. no gas leakage during 5 test periods of 15 minutes each. The temperature was cycled from 130° C. to 30° C. and back to 130° C. The pressure was cycled at 5000 psi from below, above and below at ambient temperature and farther from below at low temperature and last pressure cycle at high temperature from below.
The spring devices 31, 32 of the prototype each has a length of 6 mm in uncompressed state. Hence, the total length of the spring devices 31, 32 is 24 mm, considerably shorter than the spring devices of some prior art well tools having a length of 200-300 mm in the uncompressed state.
The total length of the prototype was approximately 86 cm, including the ratchet mechanism 60.
The connection devices 18, 19 of the prototype allows a relative movement between the respective housing devices and the respective supporting devices of ca 4 mm.
Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.
Number | Date | Country | Kind |
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20150175 | Feb 2015 | NO | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/052497 | 2/5/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2016/124735 | 8/11/2016 | WO | A |
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Number | Date | Country | |
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20170370175 A1 | Dec 2017 | US |