This application is the U.S. national phase of International Application No. PCT/EP2016/054452 filed Mar. 2, 2016 which designated the U.S. and claims priority to EP Patent Application No. 15157462.1 filed Mar. 3, 2015, EP Patent Application No. 15160029.3 filed Mar. 20, 2015 and EP Patent Application No. 15174393.7 filed Jun. 29, 2015, the entire contents of each of which are hereby incorporated by reference.
The present invention relates to a downhole stroking tool for providing an axial force in an axial direction, comprising a housing, a first chamber, a first tool part comprising a pump unit providing pressurised fluid to the chamber, a shaft penetrating the chamber, and a first piston dividing the first chamber into a first chamber section and a second chamber section. Furthermore, the invention relates to a downhole system comprising the downhole stroking tool and a driving unit, such as a downhole tractor, for propelling the system forward in a well, and to the use of a downhole stroking tool for pulling a plug in a well.
When operating in a well, a high axial force is sometimes needed to e.g. pull a plug, such as a bridge plug. However, the known tools are currently not designed to generate a sufficiently high amount of power to pull certain plugs or old plugs which are often stuck in the well due to precipitated scale on the plug.
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 tool providing a higher axial force than the known tools to be able to pull all kinds of plugs.
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 downhole stroking tool for providing an axial force in an axial direction, comprising:
By the shaft being fixed and by the housing being the piston sliding, the force generated by the downhole stroking tool is mainly transferred via the housing and not via the shaft to e.g. a plug as in prior art tools. By displacing the housing in relation to the fixated shaft and the fixated first tool part, a higher bending stiffness of the downhole stroking tool is obtained. The housing is supported along its stroke by the piston, whereby the downhole stroking tool is capable of transferring a higher axial force substantially without bending compared to prior art tools.
In an embodiment, the first chamber section and the second chamber section may be fluidly connected to the pump unit.
In this way, fluid from the pump unit can enter the first chamber section to move the housing away from the pump unit.
In another embodiment, the tool may further comprise a pressure intensifier arranged downstream of the pump unit to increase the pressure of a fluid before the fluid is fed to the chamber.
By having a pressure intensifier, the downhole stroking tool is capable of generating a higher fluid pressure than the pump unit, and thus, the downhole stroking tool is capable of providing a higher axial force than without the pressure intensifier. Due to the restrictions downhole in a well, the size of the pump unit is also restricted.
The shaft may have a through-bore for allowing an electrical conductive means to run through the shaft.
Furthermore, by the shaft being fixed and by the housing being the piston sliding, the shaft does not transfer any force during the stroke and can thus have several through-bores for fluid channels and for electrical wiring.
The downhole stroking tool may further comprise a connector configured to connect with an operational tool.
Furthermore, the housing may comprise a first end part overlapping the first tool part.
Hereby, the housing is stabilised during movement back and forth.
By having the housing overlapping the first tool part, an even higher bending stiffness of the downhole stroking tool is obtained, as the housing is also supported by the first tool part during a stroke.
Furthermore, the housing may comprise a second end part connected to the connector.
Also, the downhole stroking tool may further comprise an operational tool connected with the housing.
Moreover, the operational tool may be a fishing neck, a key tool or a setting tool.
Further, the operational tool may be electrically powered.
In an embodiment, the housing may have an inner diameter substantially corresponding to an outer diameter of the first tool part.
In addition, the housing may have an inner diameter substantially corresponding to an outer diameter of the first tool part along the first tool part which overlaps the housing.
Also, the shaft and/or the housing may comprise one or more fluid channels for providing fluid to and/or from the chamber during pressurisation of the first or the second chamber section, thereby generating a pressure on the piston.
In an embodiment, the first tool part may have at least one sealing element for providing a seal against the housing.
Furthermore, the tool may comprise a valve block for controlling which chamber section is fed the pressurised fluid and thus whether the downhole stroking tool provides an upstroke or downstroke movement.
Additionally, the housing may transfer the axial force.
The downhole stroking tool may further comprise a second chamber divided by a second piston.
Moreover, the second chamber may comprise a first chamber section and a second chamber section.
Also, the first and second chambers may be comprised in the housing.
In addition, the shaft may comprise an intermediate part separating or dividing the first and the second chamber.
The intermediate part may support the housing, allowing the housing to slide in relation to the intermediate part.
In an embodiment, the tool may be powered by a battery in the tool and thus be wireless.
Furthermore, the pump unit may be powered by high-pressured fluid from surface down through a pipe, coiled tubing or a casing.
The downhole stroking tool may further comprise an anchoring section having projectable fixation units for fixating the downhole stroking tool in a well.
In an embodiment, the anchoring section may be connected to the first tool part and be configured to anchor the first tool part in a well.
The present invention furthermore relates to a downhole system comprising the downhole stroking tool described above and a driving unit, such as a downhole tractor, for propelling the system forward in a well.
In addition, the present invention relates to a downhole system comprising the downhole stroking tool described above and a well tubular metal structure comprising an annular barrier for isolating a first zone from a second zone in an annulus surrounding the well tubular metal structure.
Furthermore, the annular barrier may comprise a tubular metal part mounted as part of the well tubular metal structure, and an expandable metal sleeve connected with the tubular metal part defining an expandable space. The annular barrier may comprise an expansion opening in the tubular metal part through which pressurised fluid enters to expand the expandable metal sleeve.
Also, the downhole stroking tool may comprise an expansion section having circumferential sealing elements arranged on each side of the expansion opening for isolating an expansion zone opposite the expansion opening.
In one embodiment, a tool end element may be connected with the expansion section, the tool end element comprising fluid channels providing fluid communication between the second chamber section and an opening in the expansion section opposite the expansion zone. This is to provide pressurised fluid into the expandable space and expand the annular barrier.
Furthermore, the fluid channel of the shaft of the downhole stroking tool may be fluidly connected with the sealing elements of the expansion section to expand the sealing elements by means of pressurised fluid from the pump unit.
In another embodiment, the second tool part, the housing and the piston of the downhole stroking tool are connected with a first end of a section shaft of the expansion section, and a second end of the section shaft may be connected to a piston sliding in a section housing, the piston dividing the section housing into a first chamber section and a second chamber section, the first chamber section being in fluid communication with an opening in the expansion section to provide pressurised fluid into the annular barrier.
In addition, the opening of the expansion section may be provided with a one-way valve or check valve.
Furthermore, the first section chamber may be fluidly connected with a part of an inside of the well tubular metal structure by means of a second fluid channel which part does not form part of the isolated zone.
Also, the second fluid channel may be provided with a one-way valve or check valve for taking in fluid from the well tubular metal structure.
Finally, the present invention relates to the use of a downhole stroking tool described above for pulling a plug in a well.
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
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.
In
The pressurisation of the first chamber section 8 generates a pressure on the piston 7 and a downstroke movement in that the housing 2 moves down, away from the pump unit 5, as shown in
By the shaft 6 being fixed and the housing 2 with the piston being slidable, the force generated by the downhole stroking tool 1 is mainly transferred via the housing and not via the shaft to e.g. a plug as in prior art tools. When transferring a high force close to the centre of the tool 1 and when the tool is not fully aligned with the element it presses onto, the shaft 6 bends easier than when being aligned with the element. When transferring the high axial force mainly via the housing 2, the force is transferred further away from the centre and thus eliminates the risk of bending when being off the centre in relation to the element. The tool 1 of the present invention is therefore capable of transferring a higher amount of force as the risk of the shaft bending while transferring a high force is substantially decreased. In prior art tools transferring the generated axial force via a shaft, the shaft bends when the force exceeds a certain level. Increasing the shaft diameter reduces the area of the piston and thus reduces the force the piston is capable of providing. Prior art tools cannot provide a force substantially above 50,000 pounds, but the tool 1 of the present invention can provide a force of 100,000 pounds. Furthermore, by moving the housing 2 in relation to the stationary shaft 6 and the stationary first tool part 4, a higher bending stiffness of the downhole stroking tool is obtained. The housing 2 is supported along its stroke by the piston 7, whereby the downhole stroking tool 1 is capable of transferring a higher axial force substantially without bending compared to prior art tools.
Furthermore, by the shaft 6 being fixed and the housing 2 with the piston sliding, the shaft does not transfer any force and thus does not have to have a certain diameter, and the shaft diameter can therefore be reduced and the piston area increased, enabling the tool 1 to generate a higher axial force.
In another embodiment, the tool 1 is powered by a battery in the tool and is thus wireless. In another, not shown, embodiment, the pump unit may be powered by high-pressured fluid from surface down through a pipe, coiled tubing or casing.
In
By having a pressure intensifier, the downhole stroking tool is capable of generating a higher fluid pressure than the pump unit, and thus, the downhole stroking tool is capable of providing a higher axial force than without the pressure intensifier. Due to the restrictions downhole in a well, the size of the pump unit is also restricted.
In
In
In
The downhole stroking tool 1 according to
In
In
In
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 gas is meant any kind of gas composition present in a well, completion, or open hole, and by oil is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil, and water fluids may thus all comprise other elements or substances than gas, oil, and/or water, respectively.
By a casing, production casing or well tubular metal structure is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.
In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor 52 may have projectable arms 56 having wheels 57, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.
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 |
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15157462 | Mar 2015 | EP | regional |
15160029 | Mar 2015 | EP | regional |
15174393 | Jun 2015 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/054452 | 3/2/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2016/139264 | 9/9/2016 | WO | A |
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International Search Report for PCT/EP2016/054452 dated Jun. 7, 2016, 11 pages. |
Extended Search Report for EP15160029.3 dated Oct. 2, 2015, 5 pages. |
Extended Search Report for EP15174393.7 dated Jan. 4, 2016, 8 pages. |
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Number | Date | Country | |
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20180030797 A1 | Feb 2018 | US |