NO347217B1

NO347217B1 - Bridge plug system

Info

Publication number: NO347217B1
Application number: NO20220465A
Authority: NO
Inventors: Arve Byberg
Original assignee: Archer Oiltools As
Priority date: 2022-04-25
Filing date: 2022-04-25
Publication date: 2023-07-10
Also published as: NO20220465A1

Description

Bridge plug system

Field of the invention

The invention relates to a downhole bridge plug system, methods for setting the bridge plug and a method for retrieving the bridge plug.

Background of the invention.

Bridge plugs are commonly used in the oil and gas industry for isolating the wellbore below the bridge plug so that work can be performed above the bridge plug while the bridge plug is a barrier against the reservoir pressure. Bridge plugs can be used as a temporary barrier in the well or as a permanent barrier. In some cases also used as a foundation for a cemented barrier in the well.

US10280706B1 discloses a hydraulic setting tool apparatus and method for drilling operations providing one-trip setting of a cement-retainer assembly and pumping of cement without excessive pulling, pushing, or twisting of the workstring, using hydraulic drilling fluid pressure and internal movement in the tool.

US3374838A discloses a fluid expansible packer and anchor apparatus.

Objects of the present invention

The object of the invention is to provide a simple, cost effective and reliable bridge plug system. Another object is to enable removal of the bridge plug in case removal without drilling is required.

Summary of the invention

The invention provides a downhole bridge plug system. The system comprises:

- a plug for sealing off a central bore of a well comprising:

- a plug mandrel,

- an anchor mechanism comprising at least one first set of slips, at least one ramp for said first set of slips and a lock ring arranged above said first set of slips, and

- a packer assembly comprising a packer element, a stop ring arranged below the packer element and a slidable compressor ring arranged above the packer element,

wherein the plug mandrel and the lock ring comprises a ratchet mechanism preventing the lock ring from sliding upwards on the plug mandrel,

- a running tool to be conveyed on a workstring for setting said plug, comprising:

- a running tool mandrel, with a central bore,

- a piston sleeve slidably arranged on the running tool mandrel with a uphole/upward facing piston area on an inside, and

- one or more upper ports arranged to provide fluid communication between the central bore and the piston area,

, and

- a tear bolt arranged to initially connect the plug to the running tool, said tear bolt is connected to the running tool mandrel in one end and to the plug mandrel in the other end, the tear bolt is arranged to tear at a predetermined tension.

The piston sleeve is arranged so that a differential pressure between the central bore and a annulus will force the piston sleeve to slide downwards on the running tool mandrel. This will move the lock ring downwards and forcing the at least one set of slips downwards and onto the at least one ramp and radially outwards to engage a wall in the well. The downwards movement and force of the lock ring is transferred through the anchor mechanism so that the compressor ring is moved axially downwards compressing the packer element axially between the compressor ring and the stop ring.

Terms like downwards/down/below and upwards/up/above is used in relation to the bottom of the well and the surface with the bridge plug system in its intended orientation in the well. Downwards/down/below being in the direction of the bottom of the well and upwards/up/above being in the direction towards the surface along the path of the well regardless of the inclination of the well.

In an embodiments the running tool further comprises:

- one or more sleeve ports in the piston sleeve, and one or more lower ports in the running tool mandrel in fluid communication with each other and arranged to provide fluid communication between the central bore and the annulus surrounding the running tool, and

- an obturator seat in the central bore between the one or more upper ports and the one or more lower ports arranged to receive an obturator to seal off the central bore.

An advantage of having radial sleeve ports in the sleeve and a set of lower ports in the running tool mandrel together with an obturator seat in the central bore is that it is possible to circulate between the central bore/workstring and the annulus/well while running the bridge plug system into the well. The workstring will then be filled by itself with well fluid while running in. With the workstring filling itself with wellfluid through the running tool there is no need to fill the workstring from surface to avoid collapse of the workstring while running into the well. This saves time while running into hole, since it typically will have to be done several times. It will also be possible to circulate between the workstring and the well to displace wellfluid or in case of a well control incident. Once an obturator is dropped into the workstring and landed in the obturator seat it will no longer be possible to circulate down the workstring and out through the one or more sleeve ports.

Fluid communication between the one or more sleeve ports and the one or more lower ports in the mandrel can be achieved by having one or more channels or an annulus between the mandrel and the piston sleeve.

The obturator can be a ball and the obturator seat can be a ball seat.

The obturator seat can in an embodiment of the invention be a shearable obturator seat, arranged to be displaced downwards to below the lower ports once sheared. This is so that fluid communication between the central bore and the annulus can be re-established after the obturator is landed in the obturator seat.

The advantage of a shearable obturator seat is that it can be sheared out after the plug is set and the running tool is free from the plug, to re-establish the ability to circulate between the workstring and the annulus via the running tool. Then the workstring drain itself while pulling out of hole after setting the plug so that spills of wellfluid on drillfloor, "pulling wet", is avoided and it is possible to circulate between the workstring and the well if needed after the plug is set.

After the obturator is landed in the obturator seat and the plug is set, pressure is further increased to above a predefined threshold so that the obturator seat shears out. Then the obturator seat with the obturator will be displaced down to a bottom of the central bore of the running tool below the lower ports of the mandrel. Then there is a path for fluid communication from inside the workstring, through the central bore of the running tool, out the lower ports and further out through the sleeve ports and into the wellbore.

In an embodiment the running tool can further comprises:

- one or more sleeve ports in the piston sleeve, and one or more lower ports in the running tool mandrel in fluid communication with each other and arranged to provide fluid communication between the central bore and a annulus surrounding the running tool,

- a flow restriction valve sleeve slidably arranged in the central bore, said valve sleeve comprises:

- a biasing member arranged to bias the flow restriction valve sleeve in the upward direction,

- one or more radial flow ports, and

- a index groove, having a first, open and a second, closed position for the flow restriction valve sleeve and its ports.

The biasing member can be a spring, such as a coil spring.

The index groove can have a first and a second downward extending branch. The second branch can extend further downwards than the first branch, the index groove can be arranged to guide the sliding motion of the flow restriction valve sleeve and limit its travel.

The running tool can further be arranged so that when the flow restriction sleeve is in a first position fluid can flow between the central bore and the annulus via the one or more radial flow ports, lower ports and sleeve ports, and when the running tool is in a second position it prevents fluid from flowing between the central bore and the annulus.

The flow restriction valve sleeve can be arranged to be pushed downward from the first position by an increase in fluid flow down the workstring to the annulus via the central bore, while being guided by the first branch. The flow restriction sleeve is then arranged to be pushed back upwards to its second position by the biasing member when said fluid flow is reduced, while being guided by the second branch.

Regaining fluid communication between the central bore and the annulus can be done by moving the piston sleeve so fare down that the upper ports of the running tool mandrel is exposed to the annulus. On possible method for moving the piston sleeve down so fare down is to have a connection with a weakling or shear screw/bolt between the piston sleeve and the plug. This connection will then pull the piston sleeve down on the running tool mandrel when the running tool is pulled up after the plug is set. When the piston sleeve is moved sufficiently fare down to expose the upper ports then the weaklink is torn off, so the running tool is completely free from the plug.

The plug can comprise the following components arranged on the plug mandrel from top to bottom:

- the lock ring, having a first ramp tapering downwards,

- the first set of slips,

- the compressor ring, having a second ramp tapering upwards and a first packer contact surface facing downwards,

- the packer element, and

- the stop ring, having a second packer contact surface facing upwards.

- the lock ring, having a first ramp tapering downwards,

- the first set of slips,

- the packer element,

- a second compressor ring, having a second packer contact surface facing upwards and a third ramp tapering downwards,

- a second set of slips, and

- the stop ring, having a fourth ramp tapering upwards.

In an embodiment of the invention the system can further comprise a J-slot overshot retrieval tool arranged to be conveyed on a workstring. The retrieval tool is arranged to latch onto the top of the plug engaging a profile protruding radially from the lock ring with a J-slot inside said retrieval tool. The plug is arranged to be released by rotating the lock ring in the right hand direction and thereby moving the lock ring upwards to retract the slips and the packer element.

The invention also provides a method for setting the plug, using the downhole bridge plug system. The method comprises the steps of:

- running into the well, the running tool being connected to the workstring and the plug being connected to the running tool,

- positioning the plug at the desired depth in the well,

- pumping down the workstring to increase the fluid pressure in the central bore to a first pressure P1, so that a differential pressure between the central bore and the annulus results in a force acting on the downhole piston area and pushes the piston sleeve downhole, the piston sleeve forces the lock ring downwards and thereby setting the plug

- increasing the pressure in the central bore further to a second pressure P2 to tear off the tear bolt so that the running tool is free from the set plug, and - pulling the running tool out of the well.

The invention also provides another method for setting the plug, using the downhole bridge plug system. This method comprises the steps of:

- letting the workstring fill itself with wellfluid through the running tool,

- positioning the plug at the desired depth in the well,

- dropping an obturator into the well and landing said obturator in the obturator seat,

- pumping down the workstring to increase the fluid pressure in the central bore above the obturator landed in the obturator seat to a first pressure P1, so that a differential pressure between the central bore and the annulus results in a force acting on the downhole piston area and pushes the piston sleeve downhole, the piston sleeve forces the lock ring downwards thereby setting the plug,

The invention also provides yet another method for setting the plug, using the downhole bridge plug system. This method comprises the steps of:

- letting the workstring fill itself with wellfluid through the running tool,

- positioning the plug at the desired depth in the well

- increasing the pressure in the central bore further to a second pressure P2 to tear off the tear bolt so that the running tool is free from the set plug, - increasing the pressure in the central bore further to a third pressure P3 to shear out the obturator seat and displace the obturator seat with the obturator to below the lower ports,

- pulling the running tool out of the well, and

- letting the workstring drain itself out through the running tool while pulling out of hole.

The invention provides yet another method for setting the plug, using the downhole bridge plug system. This method comprises the steps of:

- letting the workstring fill itself with wellfluid through the running tool while running in,

- positioning the plug at the desired target depth in the well,

- pumping down the workstring with a pump rate PR1, thereby moving the flow restriction valve sleeve downwardly from its first position,

- stopping the pumping, thereby letting the biasing member force the flow restriction valve sleeve upwardly into its second position blocking the lower ports,

- pumping down the workstring to increase the fluid pressure in the central bore to a first pressure P1, so that the differential pressure between the central bore and the annulus results in a force acting on the downhole piston area and pushes the piston sleeve downhole, the piston sleeve forces the lock ring downwardly thereby setting the slips and packer of the plug.

The above method for setting the plug can further comprises:

The invention also provides a method for retrieving the plug, set in a well, using the retrievable downhole bridge plug system. This method comprises the steps of:

- running the retrieval tool into the well on the workstring,

- latching onto the top of the plug engaging the profile protruding radially from the lock ring with the J-slot inside said retrieval tool,

rotating the workstring in the right hand direction moving the lock ring uphole/upwards on the plug mandrel so that the packer element and the slips is retracted radially inwards, and

- pulling the plug out off the well.

Description of the drawings

Fig. 1 shows the downhole bridge plug system inside a well in the state it will be in while being conveyed into the well.

Fig. 2 shows the downhole bridge plug system after a ball is dropped into the workstring and have landed in the obturator seat in the running tool. The plug is not yet set, so the slips and the packer is retracted and the tear bolt is intact.

Fig. 3 shows the downhole bridge plug system after the pressure has been increased inside the workstring above the ball to set the plug. The piston sleeve is shifted downwards on the running tool mandrel compare to Fig.1 and Fig.2. The slips of the plug is extended so that they engages the wall of the well and the packer element is sealing off the annulus between the plug and the wall of the well. In Fig.3 the plug is also released from the running tool and one can see that the tear bolt is torn off and the running tool is lifted slightly relative to the plug.

Fig. 4 shows the retrieval tool latched onto the a set plug. The plug is not yet released, so the slips are engaging the wall of the well and the packer element is still extended so that it seals off the annulus.

Fig. 5 shows the plug after the plug is released by rotating the lock ring in the right hand direction using the retrieval tool and the workstring. One can see that the lock ring is shifted upwards compare to Fig.4. The plug is now ready for being pulled out of the hole.

Fig. 6 shows an embodiment of the plug having a second set of slips below the packer element. The drawings shows the plug alone without the running tool before the slips and packer is set. This drawing is not in section as the preceding drawings are.

Fig. 7 shows an embodiment of the running tool together with a plug before the slips and packer of the plug is set. In this embodiment of the running tool the comprises a flow restriction valve sleeve having an indexing groove. The valve sleeve can be closed to set the plug by increasing the flow going through the running tool an then reduce/turned off the flow. The drawing is in section.

Fig. 8 shows the flow restriction valve sleeve with a possible embodiment of the indexing groove. The drawing is not in section.

Description of preferred embodiments of the invention

In the following an embodiment of the invention will be described with reference to the drawings. The bridge plug system 10 and how it works is described and explained using references such as upwards/up/above and downwards/down/below. Such terms is used in relation to the bottom of the well and the surface and with the bridge plug system oriented as intended for use this is also how it is displayed in the figures. Downwards/down/below being in the direction of the bottom of the well and upwards/up/above being in the direction towards the surface along the path of the well regardless of the inclination of the well.

In Fig.1 a bridge plug system 10 is seen in the state and orientation it will be in while being run into a well 1. The well 1 will usually be cased with a casing of some sort wherein the plug 20 is run in and set. In this state the main components of the system 10 is a plug 20 in the bottom end of the figure and a running tool 30 above the plug 20. The running tool 30 is connected to a pipe workstring 3 and the plug 20 is connected to the running tool 30.

The plug 20 comprises a plug mandrel 26, a packer assembly for sealing off an annulus 2 between the wall of the well 1, usually the casing, and the plug 20 and a anchor mechanism for engaging the wall of the well 1 for holding the plug 20 firmly in place.

The anchor mechanism is arranged on the plug mandrel 26 and comprises a set of slips 21, at least one ramp 22 and a lock ring 27. The set of slips 21 can be forced radially out towards the wall of the well 1 by forcing the ramp 22 underneath the slips 21. In the embodiment in the figures the ramp 22 is on the lower axial end of the locking ring 27 and in addition there is also a ramp 22 on the opposite, lower end of the slips 21. The lock ring 27 together with the plug mandrel 26 is arranged so that it together works as a ratchet mechanism making it possible to slide the lock ring downwards on the plug mandrel 26, but not possible to slide it back upwards once pushed down, but in an embodiment unscrewing the lock ring 27 is possible if required.

The packer assembly is arranged on the plug mandrel 26 below the anchor mechanism. The packer assembly comprises a packer element 23, a stop ring 24 and a slidable compressor ring 25. The slidable compressor ring 25 comprises the second, lower ramp 22. The stop ring 24 is fixed on the plug mandrel 26 so that it is prevented from sliding axially on the plug mandrel 26. The packer element 23 is arranged on the plug mandrel 26 below the slidable stop ring 25 and above the stop ring 24, as seen in Fig.1.

The plug assembly 20 is pre-assembled connected to the running tool 30 via the tear bolt 35 while running in.

The running tool 30 comprises a running tool mandrel 31 having a central bore 32, and a piston sleeve 33 slidably arranged on the running tool mandrel 31. The running tool mandrel 31 comprises upper ports 31.1 radially extending out from the central bore 32 through the running tool mandrel 31. The piston sleeve 33 comprises an upwards facing conical piston area 33.1 on the inside, so that a force acting on the piston area 33.1 will force the piston sleeve 33 downwards relative to the running tool mandrel 31. The upper ports 31.1 extend from the central bore 32 to a narrow piston sleeve annulus 38 between the running tool mandrel 31 and the piston sleeve 33. The narrow annulus is barley visible in the figures. An upper 36.1 and a lower seal 36.2 is arranged on the running tool mandrel 31. The upper seal 36.1 is above the upper ports 31.1 and the lower seal 36.2 is placed below the piston area 33.1. The piston area 33.1 is in fluid communication with the central bore 32 through the upper ports 31.1 and the piston sleeve annulus 38.

The piston sleeve 33 further comprises a set of radial sleeve ports 33.2 and the running tool mandrel 31 further comprises a set of radial lower ports 31.2. Fluid communication between the central bore 32 and the annulus 2 is provided via the lower ports 31.2 and the sleeve ports 33.2. A circulation annulus 37 below the lower seal 36.2 or axial channels in the running tool mandrel 31 or the piston sleeve 33 can be in place to provide for fluid communication between the lower ports 31.2 and the sleeve ports 33.2, since mandrel 31 and the sleeve 33 are axially movable relative to each other. Both the sleeve ports 33.2 and the lower ports 31.2 is arranged below the lower seal 36.2.

An obturator seat 34 is arranged in the central bore 32 between the upper ports 31.1 and the lower ports 31.2. The obturator seat 32 is arranged for receiving a well tool obturator 40 such as a ball. The obturator 40 is arranged to seal off the central bore 32, as seen in Fig.2. The obturator seat 34 is initially held in place by shear screws, pins, bolts or similar, that will be sheared off at a predefined differential pressure across the obturator seat 34.

The plug 20 is connected to the running tool 30 by a tear bolt 35. The tear bolt 35 is arranged to tear at a predetermined tension so that the plug 20 is released permanently from the running tool 30. In an embodiment of the invention the tear bolt 35 is connected to a bottom plug 35.1 in the running tool mandrel 31, and to a top plug 28 in the plug mandrel 26, as seen in Fig.1 - 3.

The operation of the system 10 will now be discussed in sequence with reference to the drawings.

Fig. 1 shows the system 10 in the state it is when it is run into the well 1. The plug 20 is connected to the running tool 30 with the piston sleeve 33 in an upper position and the packer element 23 and the slips 21 is retracted. In this state it is possible to circulate well fluid between the workstring 3 and the annulus 2 via the lower port 31.2, the circulation annulus 37 and the sleeve ports 33.2. The sleeve ports outer aperture to the outer face of the piston sleeve 33 is not visible in the section shown in Fig.1, but are clearly visible in Fig.2.

Fig. 2 shows the system in the same state as in Fig.1, but now a obturator 40 in this case a ball is dropped into the workstring 3 and has arrived at the running tool 30. The obturator 40 has landed in the obturator seat 34, so that it at least partly seals off the central bore 32 of the running tool 30 below the obturator seat 34. At this point in time the system 10 is placed in the well 1 at the target depth, or close to the target depth where it is to be set. Pressure can now be increased in the central bore 32 above the obturator seat 34 using rig pumps at the surface pumping down the workstring 3. Since the central bore is sealed off above the lower ports 31.2, a pressure increases in the central bore 32 above the obturator seat 34 will be seen, resulting in a differential pressure relative to the annulus 2. This differential pressure will act with a force on the piston area 33.1 and will have a force component parallel to the axial direction of the running tool 30. This will push the piston sleeve 33 downwardly relative to the running tool mandrel 31. The piston sleeve 33 will push down on the lock ring 27 while the plug mandrel 26 remains fixed to the running tool mandrel via the tear bolt 35.

The lock ring 27 will push down (in the axial direction) on the slips 21 and at the same time the ramp 22 will be forced underneath the slips 21 forcing the slips to expand radially outwards. As the slips 21 are moved downwardly they will gradually move onto the second ramp 22 on the slidable compressor ring 25 and at the same time force the slidable compressor ring 25 downwards. The slidable compressor ring 25 will compress the packer element 23 since the packer element cannot move further downwardly due to the stop ring 24. Hence, the packer element 23 is forced to extends radially outwards from the plug mandrel 26.

The slips 21 are now in contact with the wall of the well 1, here shown as the casing, and hold the plug 20 in place and the packer element 23 will be forced against the wall of the well 1 sealing off the well 1.

The next step is to further increase the pressure to a predetermined level where the tear bolt 35 will tear off. Then the running tool 30 will be free from the plug 20. The lock ring 27 will remain its position on the plug mandrel 26 due to the ratchet mechanism so that the slips 21 and the packer element 23 remain extended.

After tearing the tear bolt 35 the next step is to again further increase the pressure to shear out the obturator seat 34 to reenable fluid circulation between the workstring 3 and the annulus 2 through the lower ports 31.2. When the pressure above the obturator seat 34 is increased to above a predetermined level the obturator seat 34 shears out and the obturator seat 34 with the obturator 40 is displaced to the bottom of the central bore 32 below the lower ports 31.2 in the running tool mandrel 31, please see Fig.3.

In Fig.3 the running tool 30 is released from the plug 20 and ready to be pulled out of the well 1. The plug 20 is set, the running tool 30 is free from the plug 20 and the obturator seat 34 is sheared out.

In an embodiment of the invention the plug 20 can also be a retrievable bridge plug 20, so that a retrieval tool 50 can be conveyed into the well 1 on the workstring 3 to latch onto the plug 20, release it and pull it to surface.

The retrieval tool 50 is arranged to latch/connect to the plug 20 using a J-slot mechanism. In a possible embodiment the retrieval tool 50 is an overshoot with a J-slot on an inside. The retrieval tool 50 slides onto the top of the plug 20 where an outwards protruding profile on the plug 20 engages with the J-slot on the retrieval tool 50. The lock ring 27 can be moved upwardly to release the plug 20 by rotating the lock ring 27 in the right hand direction using the retrieval tool 50.

Fig. 4 shows the retrieval tool on the plug 20. The plug 20 is still set, with the slips 21 and the packer element 23 engaging the wall of the well 1.

In Fig.5 the lock ring 27 have been rotated so that the lock ring 27 is moved upwardly for allowing the packer element 23 and slips 21 to retract radially inwardly to disengage from the wall of the well 1. The plug 20 is now ready to be pulled out of the well 1.

Fig. 6 shows another embodiment of the plug 20 having a second set of slips 21.2 below the packer element 23. In this embodiment there is also a second compressor ring 25.3 having a ramp 22.3 tapering down towards the second set of slips 21.2 below the packer element 23. The stop ring is also equipped with a ramp 22.4 in this embodiment. Apart from the mentioned differences the main components of this embodiment of the plug 20 is the same as for the embodiment of the plug 20 with only one set of slips 21. This embodiment of the plug 20 is also operated in the same manner as the plug 20 with only one set of slips 21.

Fig. 7 shows another embodiment of the running tool 30. This embodiment of the running tool 30 is not operated by dropping a obturator 40 and increasing the pressure in the central bore 32 above the obturator seat 34. In this embodiment a flow restriction valve sleeve 39 with a indexing groove 39.3 is shifted to close off the fluid communication between the central bore 32 and the annulus 2. After the fluid communication is closed off by shifting the flow restriction valve sleeve 39 pressure can be increased inside the central bore 32 to set the set of slips (one or two sets of slips 21, 21.2 dependent on which embodiment of the plug 20 is used) and the packer element 23.

The flow restriction valve sleeve 39 with its indexing groove 39.3 is seen in Fig.8. The indexing groove 39.3 can have a first 39.4 and a second 39.5 downward extending branch, wherein the second branch 39.5 extends further downwards than the first branch 39.4, the groove 39.3 is arranged to guide the sliding motion of the flow restriction valve sleeve 39 and limit its travel.

The running tool 30 is arranged so that when the flow restriction valve sleeve 39 is in a first position fluid can flow between the central bore 32 and the annulus 2 via the one or more radial flow ports 39.2, lower ports 31.2 and sleeve ports 33.2. When the flow restriction valve sleeve 39 is in a second position it prevents fluid from flowing between the central bore 32 and the annulus 2.

The flow restriction valve sleeve 39 is arranged to be pushed downwardly from the first position by an increase in fluid flow down the workstring 3 to the annulus 2 via the central bore 32. The flow restriction valve sleeve 39 is being guided by the first branch 39.4 while being forced downwardly by the fluid flow. The flow restriction valve sleeve 39 is arranged to be pushed back upwardly to its second position by a coil spring 39.1 (biasing member 39.1) when said fluid flow is reduced. The flow restriction valve sleeve 39 is being guided by the second branch 39.5 while being forced upwardly by the coil spring 39.1. Since the second branch extends further downwards on the valve sleeve 39 the sleeve is positioned further up in the central bore after being pushed down. As a result of this a sleeve seal area 39.7 is now positioned so that it covers the lower ports 31.2.

Claims

1. Downhole bridge plug system (10), wherein the system (10) comprises:

- a plug (20) for sealing off a central bore of a well (1) comprising:

- a plug mandrel (26),

- an anchor mechanism comprising at least one first set of slips (21), at least one ramp (22) for said first set of slips (21) and a lock ring (27) arranged above said first set of slips (21), and

- a packer assembly comprising a packer element (23), a stop ring (24) arranged below the packer element (23) and a slidable compressor ring (25) arranged above the packer element (23),

wherein the downhole bridge plug system (10) is characterized in that the plug mandrel (26) and the lock ring (27) comprises a ratchet mechanism preventing the lock ring (27) from sliding upwards on the plug mandrel (26), - a running tool (30) to be conveyed on a workstring (3) for setting said plug (20), comprising:

- a running tool mandrel (31), with a central bore (32),

- a piston sleeve (33) slidably arranged on the running tool mandrel (31) with a uphole facing piston area (33.1) on an inside, and

- one or more upper ports (31.1) arranged to provide fluid communication between the central bore (32) and the piston area (33.1),

and

- a tear bolt (35) arranged to initially connect the plug (20) to the running tool (30), said tear bolt (35) is connected to the running tool mandrel (31) in one end and to the plug mandrel (26) in an opposite end, the tear bolt (35) is arranged to tear at a predetermined tension,

said piston sleeve (33) being arranged so that a differential pressure between the central bore (32) and a annulus (2) will force the piston sleeve (33) to slide downwardly on the running tool mandrel (31), moving the lock ring (27) downwardly and forcing the at least one set of slips (21) downwardly and onto the at least one ramp (22) and radially outwardly to engage a wall in the well (1), the downwards movement and force of the lock ring (27) is transferred through the anchor mechanism so that the compressor ring (25) is moved axially downwardly compressing the packer element (23) axially between the compressor ring (25) and the stop ring (24).

2. Downhole bridge plug system (10), according to claim 1, wherein the running tool (30) further comprises:

- one or more sleeve ports (33.2) in the piston sleeve (33), and one or more lower ports (31.2) in the running tool mandrel (31) in fluid communication with each other and arranged to provide fluid communication between the central bore (32) and the annulus (2) surrounding the running tool (30), and

- an obturator seat (34) in the central bore (32) between the one or more upper ports (31.1) and the one or more lower ports (31.2) arranged to receive an obturator (40) to seal off the central bore (32).

3. Downhole bridge plug system (10), according to claim 2, wherein the obturator seat (34) is a shearable obturator seat, arranged to be displaced downwardly to below the lower ports (31.2) once sheared, so that fluid communication between the central bore (32) and the annulus (2) can be re-established after the obturator is landed in the obturator seat (34).

4. Downhole bridge plug system (10), according to claim 1, wherein the running tool (30) further comprises:

- one or more sleeve ports (33.2) in the piston sleeve (33), and one or more lower ports (31.2) in the running tool mandrel (31) in fluid communication with each other and arranged to provide fluid communication between the central bore (32) and a annulus (2) surrounding the running tool (30),

- a flow restriction valve sleeve (39) slidably arranged in the central bore (32), said valve sleeve (39) comprises:

- a biasing member (39.1) arranged to bias the flow restriction valve sleeve (39) in the upward direction,

- one or more radial flow ports (39.2), and

- a index groove (39.3), having a first, open and a second, closed position for the flow restriction valve sleeve (39) and its ports (39.2).

5. Downhole bridge plug system (10) according to any of the preceding claims, wherein the plug (20) comprises, arranged on the plug mandrel (26) from top to bottom:

- the lock ring (27), having a first ramp (22.1) tapering downwards,

- the first set of slips (21),

- the compressor ring (25), having a second ramp (22.2) tapering upwards and a first packer contact surface (25.1) facing downwards,

- the packer element (23), and

- the stop ring (24), having a second packer contact surface (25.2) facing upwards.

6. Downhole bridge plug system (10) according to any of the claims 1-4, wherein the plug (20) comprises, arranged on the plug mandrel (26) from top to bottom:

- the lock ring (27), having a first ramp (22.1) tapering downwards,

- the first set of slips (21),

- the packer element (23),

- a second compressor ring (25.3), having a second packer contact surface (25.2) facing upwards and a third ramp (22.3) tapering downwards,

- a second set of slips (21.2), and

- the stop ring (24), having a fourth ramp (22.4) tapering upwards.

7. Downhole bridge plug system (10) according to any of the previous claims, wherein the system (10) further comprises a J-slot overshoot retrieval tool (50) arranged to be conveyed on a workstring (3), wherein said retrieval tool (50) is arranged to latch onto the top of the plug (20) engaging a profile protruding radially from the lock ring (27) with a J-slot inside said retrieval tool (50) and wherein the plug (20) is arranged to be released by rotating the lock ring (27) in the right hand direction and thereby moving the lock ring (27) upwardly to retract the slips (21) and the packer element (23).

8. Method for setting the plug (20), using the downhole bridge plug system (10), according to claim 1, wherein the method comprises the steps of:

- running into the well (1), the running tool (30) being connected to the workstring (3) and the plug (20) being connected to the running tool (30), - positioning the plug (20) at the desired target depth in the well (1),

- pumping down the workstring to increase the fluid pressure in the central bore (32) to a first pressure P1, so that a differential pressure between the central bore (32) and the annulus (2) results in a force acting on the downhole piston area (33.1) and pushes the piston sleeve (33) downhole, the piston sleeve (33) forces the lock ring (27) downwardly and thereby setting the plug - increasing the pressure in the central bore (32) further to a second pressure P2 to tear off the tear bolt (35) so that the running tool (30) is released from the set plug (20), and

- pulling the running tool (30) out of the well (1).

9. Method for setting the plug (20), using the downhole bridge plug system (10) according to claim 2, wherein the method comprises the steps of:

- running into the well (1), the running tool (30) being connected to the workstring (3) and the plug (20) being connected to the running tool (30), - letting the workstring (3) fill itself with wellfluid through the running tool (30) while running in,

- positioning the plug (20) at the desired target depth in the well (1),

- dropping an obturator (40) into the well (1) and landing said obturator (40) in the obturator seat (34),

- pumping down the workstring to increase the fluid pressure in the central bore (32) above the obturator (40) landed in the obturator seat (34) to a first pressure P1, so that a differential pressure between the central bore (32) and the annulus (2) results in a force acting on the downhole piston area (33.1) and pushes the piston sleeve (33) downhole, the piston sleeve (33) forces the lock ring downwardly thereby setting the plug (20),

- increasing the pressure in the central bore (32) further to a second pressure P2 to tear off the tear bolt (35) so that the running tool (30) is free from the set plug (20), and

- pulling the running tool (30) out of the well (1).

10. Method for setting the plug (20), using the downhole bridge plug system (10), according to claim 3, the method comprises the steps of:

- positioning the plug (20) at the desired target depth in the well (1),

- pumping down the workstring (3) to increase the fluid pressure in the central bore (32) above the obturator (40) landed in the obturator seat (34) to a first pressure P1, so that a differential pressure between the central bore (32) and the annulus (2) results in a force acting on the downhole piston area (33.1) and pushes the piston sleeve (33) downhole, the piston sleeve (33) forces the lock ring (27) downwardly thereby setting the plug (20),

- increasing the pressure in the central bore (32) further to a second pressure P2 to tear off the tear bolt (35) so that the running tool (30) is free from the set plug (20),

- increasing the pressure in the central bore (32) further to a third pressure P3 to shear out the obturator seat (34) and displace the obturator seat (34) with the obturator (40) to below the lower ports (31.2),

- pulling the running tool (30) out of the well (1), and

- letting the workstring (3) drain itself out through the running tool (30) while pulling out of hole.

11. Method for setting the plug (20), using the downhole bridge plug system (10), according to claim 4, the method comprises the steps of:

- positioning the plug (20) at the desired target depth in the well (1),

- pumping down the workstring (3) with a pump rate PR1, thereby moving the flow restriction valve sleeve (39) downwardly from its first position,

- stopping the pumping, thereby letting the biasing member (39.1) force the flow restriction valve sleeve (39) upwardly into its second position blocking the lower ports (31.2),

- pumping down the workstring (3) to increase the fluid pressure in the central bore (32) to a first pressure P1, so that the differential pressure between the central bore (32) and the annulus (2) results in a force acting on the downhole piston area (33.1) and pushes the piston sleeve (33) downhole, the piston sleeve (33) forces the lock ring (27) downwardly thereby setting the slips (21) and packer (23) of the plug (20).

12. Method for setting the plug (20), according to claim 11, wherein the method further comprises:

- pulling the running tool (30) out of the well (1).

13. Method for retrieving the plug (20), sett in a well (1) using the retrievable downhole bridge plug system (10) according to claim 7, wherein the method comprises the steps of:

- running the retrieval tool (50) into the well (1) on the workstring (3), - latching onto the top of the plug (20) engaging the profile protruding radially from the lock ring (27) with the J-slot inside said retrieval tool (50),

- rotating the workstring (3) in the right hand direction moving the lock ring (27) uphole on the plug mandrel (26) so that the packer element (23) and the slips (21) is retracted radially inwardly, and

- pulling the plug (20) out off the well (1).