NO20220698A1

NO20220698A1 - A system comprising a pressure actuated valve for use in injection wells

Info

Publication number: NO20220698A1
Application number: NO20220698A
Authority: NO
Inventors: Bjørnar Werswick; Christian Nomme
Original assignee: Inflowcontrol As
Priority date: 2022-06-20
Filing date: 2022-06-20
Publication date: 2023-12-21
Also published as: WO2023247485A1

Description

A system comprising a pressure actuated valve for use in injection wells

Field of the invention

The invention concerns system comprising a pressure activated valve to allow flow of fluid from inside a production string and to prevent flow of fluid into the production string, and a method using such a pressure activated valve. The valve is particularly useful when fluid is injected into the production string following activation and opening sequences after an installation and commissioning process.

Background of the invention

In oil and gas production an injection well, i.e. a well / bore / shaft / hole intended for injection of fluid, has as a typical objective to maintain pressure in a reservoir or to heat and/or lower the oil’s viscosity. For example, water-injection wells are common offshore, where filtered and treated seawater is injected via a production string into a lower waterbearing section of the reservoir.

Injection wells are also used in fields such as waste disposal, waste site remediation, aquifer recharge and geothermal energy. Furthermore, fluids may be injected for the purpose of cleaning tools or stimulating the well.

In the particular process of installation and commissioning of a production string, it is considered desirable to allow for injection of fluid from inside to outside the production string after the activation and opening sequences have been completed. That is, injection of fluids into an annulus of the wellbore by ensuring an internal pressure within the string that is higher than an outside pressure. Furthermore, flow of fluid in the opposite direction, into the production string, should be prevented.

Downhole fluid flow control systems configured to control inflow of formation fluids is known. See e.g. patent publication WO 2014/149049 A1. However, this solution is not suitable for release of injection fluids from the production string.

The purpose of the present invention is to overcome the shortcomings of the prior art and to obtain further advantages.

Summary of the invention

The invention is set forth and characterized in the main claims, while the dependent claims describe other characteristics of the invention.

In a first aspect, the invention concerns a system for preventing fluid to flow into a tubular production string, typically during injection of fluid after completion of an installation and commissioning of the production string.

In addition to the production string or a production string joing, the system comprises a production string sleeve and one or more pressure activated valves (PAVs).

The tubular production string extends in a longitudinal direction and comprises a base wall and one or more outflow ports creating fluid communication through the base wall.

The production string sleeve surrounds the circumference of the base wall across an longitudinal length Lsleeve, wherein an inner surface of the production string sleeve and the outer surface of the base wall enclose a cavity which includes the outflow port(s).

The one or more pressure activated valve(s) is/are arranged within the cavity and comprise(s) a cylinder comprising an open first longitudinal end and an open second longitudinal end, a hollow cylindrical piston movably arranged within the cylinder, a seal such as an O-ring arranged to interact with the piston and the cylinder and a stopper fixed to the piston. The seal is preferably arranged between the inner wall of the cylinder and the outer wall of the piston.

The cylinder is arranged such that a closed flow path is formed within the cavity, between the second longitudinal end and the outflow port.

The piston comprises an open first longitudinal end section, a closed second longitudinal end section and a radially arranged opening adjacent to the second longitudinal end section.

Since the piston is hollow, fluid is allowed to enter into the open first longitudinal end section, but is hindered to discharge from the closed second longitudinal end section.

The cylinder further comprises a slot for receiving the stopper. The slot is further configured to guide the stopper, and thereby also the piston, from a first position P1, via a second position P2 and to a third position P3.

In the first position P1, the piston is positioned in a pretensioned position by one more springs such that the stopper is abutting a first end of the slot. The piston is arranged such that the radially arranged opening(s) and the seal are located within the cylinder, thereby hindering any fluid from flowing through the pressure activated valve.

The second position P2 is reached by compressing the spring(s) set by an internal pressure exerted on the piston. The pressure forces the piston in an at least partly helical path towards the first longitudinal end of the cylinder until the stopper is abutting a second end of the slot corresponding to the second position P2.

Finally, the stopper (and thus the piston) further moves to the third position P3 by releasing the internal pressure exerted on the piston. The release causes the piston to move in a path governed by the design of the slot towards the second longitudinal end of the cylinder until the stopper abuts a third end of the slot (i.e. P3) such that the at least one radially arranged opening and the seal are located outside the cylinder, thereby allowing fluid to pass through the cylindrical piston.

Hence, when fluid flow between an annulus of a well and the production string should be prevented, for example during installation and commissioning, the pressure activated valve should be closed, i.e. in the first position P1.

After completion of activation and opening sequences, it may be desirable to inject fluid such as seawater into the production string, Such injection fluid may be allowed to discharge through the outflow port(s) by applying an internal pressure within the production string which is higher than the pressure in the annulus / wellbore. At least for a limited time, this pressure may be sufficiently high to expose the pressure activated valve to an internal pressure that causes the stopper to overcome the force set by the at least one spring, thereby moving from the first position P1 to the second position P2, and then, by releasing the internal pressure to a level below the force set up by the at least one spring, to the third position P3.

In an advantageous exemplary configuration, the system comprises a plurality of outflow ports, for example in form of perforations and/or an inflow control device ICD allowing flow of fluid from the production string to its surroundings. Such ICD may be an autonomous ICD.

In another advantageous exemplary configuration, the cylinder comprises two identical slots and the piston comprises two stoppers, wherein the two identical slots and the two stoppers are arranged on oppositely facing sides of the cylinder and piston, respectively.

In yet another advantageous exemplary configuration, the radially arranged opening has one of an oblong shape, an oval shape, and a rounded corner rectangular shape, and wherein the radially arranged opening(s) extend(s) in a longitudinal direction of the piston.

In yet another advantageous exemplary configuration, the radially arranged opening(s) has/have longitudinal length(s) extending from any one of 5% to 60 % or 10% to 50% or 10% to 40% of a maximum longitudinal length of the piston.

In yet another advantageous exemplary configuration, the radially arranged opening(s) has/have a circumferential extend of any one of 20 ̊ to 90 ̊ or 30 ̊ to 80 ̊ or 40 ̊ to 70 ̊.

In yet another advantageous exemplary configuration, the piston comprises a plurality of radially arranged openings, for example three or more evenly distributed around the circumference of the closed second longitudinal end section of the piston.

In yet another advantageous exemplary configuration, the piston has a shorter longitudinal length than the cylinder.

In yet another advantageous exemplary configuration, the seal is arranged circumferentially at the second longitudinal end section to seal the piston from the cylinder when the piston is in the first position P1 or between the first position P1 and second position P2, thereby hindering any fluid from flowing through the pressure activated valve.

In yet another advantageous exemplary configuration, the at least one spring is arranged within at least one recess situated between the piston and the cylinder. In this particular configuration one end of the at least one spring abuts a first piston rim of the piston and an opposite end of the at least one spring abuts a first cylinder rim of the cylinder arranged closer to the first longitudinal end of the cylinder relative to the first piston rim. The longitudinal position of the first piston rim is preferably at or near the stopper.

In a first aspect, the invention concerns a method for preventing fluid flowing into a production string using a system as described above.

The method comprises the steps of:

- arranging the piston of the pressure activated valve in the closed first position P1, wherein the piston is exposed to a bias pressure set by the spring force from the at least one spring; - exerting an internal pressure above the bias pressure from the at least one spring, wherein the internal pressure is exerted from the production string towards the pressure activated valve such that the piston moves into the closed second position P2; and

- releasing the internal pressure forcing the piston to the open, third position, P3.

Hence, the inventive system comprises a pressure activated valve (PAV) mounted between a sand-screen and outflow ports of a production string, and a method which involves use of the PAV.

The outflow ports may be perforations and/or ICD’s. The PAV is preferably closed during installation and commissioning of the production string to assure that no fluid flows through the outflow ports. The PAV retains pressures in both directions i.e. an external pressure from the reservoir and an internal pressure from the production string up to a set value/design pressure. At an internal pressure above the set value, the PAV will be activated and then opened for flow when the pressure is released. Once the PAV is activated/open it may be permanently or temporarily open for flow in both directions depending on the configuration. The PAV does not have to restrict or interfere with the base pipe standard full internal diameter and can be fitted to different sized pipes and sand screen configurations.

The PAV of the present invention is hence configured to prevent fluid from running between an annulus and an inner volume of the production string, at least during installation and commissioning of the production pipe within a well bore.

It should be understood that the longitudinal direction of the cylinder may be the same as the longitudinal direction of the production string.

Further, the term “longitudinal direction” should be understood as the direction along the longitudinal length of the cylinder of the PAV.

The term “longitudinal distance” should be understood as a distance along the longitudinal direction of the cylinder.

The term “set value/design pressure” is the spring force that the piston is exposed to in its first position before activation of the PAV by the activation pressure. Hence the design pressure can be understood as the pressure generating a force that is equal to the spring’s pretensioned force when the piston is positioned in the pretensioned first position wherein the stopper is preloaded. Hence, pressure lower than the design pressure will not move the piston while pressure above the design pressure will move the piston.

The term “activation pressure” should be understood as the internal pressure needed to be exerted on the piston to move the piston from the first position to the second position.

It should be understood that the movement of the piston within the cylinder is dependent on the path of the slot. Together with the pressure exerted/not exerted on the piston, it is the interaction between the slot and the stopper that decides the movement of the piston within the cylinder.

A person skilled in the art will understand that the activation pressure necessary to activate the PAV is not an internal pressure of a certain value, but an internal pressure above a certain value (set value/design pressure) for activating the PAV, hence moving the piston from the first to the second position.

A person skilled in the art will understand that the piston of the PAV can be moved back to the second position, P2, after being arranged at the third position, P3, by means of e.g. an additional mechanisms such as an additional spring that use flow or pressure differentials such that the piston and hence the seal can be re-engaged and be temporarily closed.

For example, the piston of the PAV can be moved back towards the second position, P2, after being arranged at the third position, P3, if the PAV is made such that it is biased to close the opening in an intermediate position, e.g. by shortening the stroke of the spring and adding a second opposing spring. In this design the PAV will obtain a check-valve function after activation. It will open on flow from the well by the external pressure, but close if pressure is reversed. Increase in external pressure will first seat the seal in the intermediate position between the second position P2 and the third position P3, then the piston will move inside the cylinder to position P2 where the pressure can further be increased without movement of the piston. When the pressure is again released the piston will go back to the intermediate check valve state i.e. the piston will be moved into the intermediate position.

The specific design pressure and internal activation pressure can be varied over a large range by using springs with different characteristics/stiffness.

Above-discussed preferred and/or optional features of each aspect may be used, alone or in appropriate combination, in the other aspects of the invention.

Brief description of the drawings

These and other characteristics of the invention will be clear from the following description of embodiments, given as non-restrictive examples, with reference to the attached sectional sketches and drawings wherein:

Fig. 1 is cross sectional view of a system having a production string, PAVs and a sand screen, wherein fig. 1A shows the entire circumference of the system and fig. 1B shows in further detail a framed part of the system containing a PAV.

Fig. 2 is an open/transparent perspective view of the system of the invention showing the sand screen, PAVs and AICV.

Fig. 3 is a perspective view of the inventive PAV according to the first example embodiment.

Fig. 4A is a cross-sectional view of the first example embodiment of the inventive PAV in the first position P1.

Fig. 4B is a cross-sectional view of the first example embodiment of the inventive PAV in the second position P2.

Fig. 4C is a cross-sectional view of the first example embodiment of the inventive PAV in the third position P3.

Fig. 5A is an open/transparent perspective view of the first example embodiment of the inventive PAV in the first position P1.

Fig. 5B is an open/transparent perspective view of the first example embodiment of the inventive PAV in the second position P2.

Fig. 5C is an open/transparent perspective view of the first example embodiment of the inventive PAV in the third position P3.

In the drawings, like reference numerals have been used to indicate like parts, elements or features unless otherwise explicitly stated or implicitly understood from the context.

Detailed description

In the following, embodiments of the invention will be described in more detail with reference to the drawings. However, it is specifically intended that the invention is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

It is appreciated that certain features of the invention, which, for clarity, have been described above in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which, for brevity, have been described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. In particular, it will be appreciated that features described in relation to one particular embodiment may be interchangeable with features described in relation to other embodiments.

Fig. 1A shows a cross section of a layout of a production string 10 with a sand screen 3, PAV 1 and a plurality of perforations acting as outflow ports 2. As shown, a plurality of PAVs 1 can be circumferentially distributed around the base wall 10a of the annular production string 10. Further, Fig. 1B shows in more detail the orientation of the PAV 1 relative to the sand screen 3 and the cavity 13.

Both the PAV 1 and the outflow ports 2 are arranged within a cavity 13 enclosed by an outer surface of the base wall 10a and an inner wall of a production string sleeve 11 surrounding the base wall 10a a certain length L.

The number and diameter of the outflow ports 2 are adjusted to ensure sufficient discharge of fluid injected into the production string 10.

As shown in Fig. 1A, the PAVs 1 do not restrict or interfere with the production string’s 10 standard full internal diameter ID. During injection of fluid into the production string, fluid passes through the outflow ports 2, through the PAV 1 set in open position and through the sand screen 3.

Fig. 2 is a perspective view of how a plurality of PAVs 1 can be arranged around the base wall 10a of the production string 10 and shows how the system of the invention comprising the production string sleeve 11, the sand screen 3, the PAVs 1 and the outflow ports 2 are assembled. Each PAV 1 may be mounted into a ring 200. The ring can contain a single PAV 1 or a plurality of PAVs 1 as shown. The ring 200 is welded to the production string 10, for example directly on the base wall 10a, such that flow or pressure communication from inside the production string 10 must go through the PAVs 1. The PAVs 1 are sealed against the ring 200 using seals such as polymer, elastomer or metal seals. When internal pressure acts on the piston 104 of each PAV 1 (for example by pressurizing the inner volume of the production string 10), spring forces will open them all up for fluid flow when the internal pressure is released (see further details below).

Fig. 3 is a perspective view of a PAV 1 according to an exemplary embodiment of the PAV 1 showing the cylinder 102 having two slots 110, where only one is visible. Further, a stopper 108 protruding from the piston 104 is arranged in a first position P1 which is pretensioned by the force from a spring 106 into the shown abutting position.

Figs. 4A to 4C are cross-sectional views of the PAV 1 shown in Fig. 3 and Figs 5A to 5C are open transparent side views of the PAV 1 shown in Figs. 4A to 4C. The PAV 1 is shown in the pretensioned closed position P1 in Figs. 4A and 5A, in a closed second position P2 in Figs. 4B and 5B and in an open third position P3 in Figs. 4C and 5C.

With reference to Figs. 3, 4A to 4C and 5A to 5C, the PAV 1 comprises a hollow cylinder 102 having a moveable cylindrical piston 104 arranged therein. The piston 104 is configured to move in the longitudinal direction L (see Fig. 3) of the cylinder 102.

The piston 104 is hollow and open at a first longitudinal terminal end 104c of a first end section 104b, thus allowing fluid to enter into the piston 104, and is closed at a second longitudinal terminal end 104d of a second end section 104a, thus hindering fluid from passing therethrough. The entire first end section 104b is closed.

The radially arranged openings 112 of the piston 104 penetrate the second end section 104a of the piston 104, thus allowing fluid to pass through the PAV 1 when the seal/O-ring 113 and the openings 112 are arranged outside the cylinder 102, i.e. when the PAV 1 is in the third (open) position P3 as shown in Figs. 4C and 5C. The openings 112 may have a longitudinal oblong shape. As shown, the second end section 104a of the piston 104 comprises the seal/O-ring 113 which sealingly arranges the piston 104 within the cylinder 102 when the PAV 1 is closed.

The spring 106 is in the exemplary embodiment arranged within a recess between the piston 104 and the cylinder 102 and abuts a first piston rim 105 of the piston 104 at the one end which can be arranged near or approximate to the stoppers 108,108’ and a first cylinder rim 103 of the cylinder 102 at the other opposite end being arranged closer to the first longitudinal end 102b of the cylinder 102.

In other words, the piston 104 has a larger outer diameter at an area which includes the stoppers 108,108’ such that the outer surface of the piston 104 facing the inner surface of the cylinder 102 comprises the first piston rim 105. Further, an area of the cylinder 102 including the first end 102b of the cylinder 102 has a smaller inner diameter than the remaining part of the inner surface of the cylinder 102 such that the inner surface of the cylinder 102 comprises the first cylinder rim 103.

As seen in Fig. 4A and 5A the spring 106 is pretensioned between the first piston rim 105 and the first cylinder rim 103 when the piston 104 is arranged in the first position P1.

In this first position P1, the spring force is directed from the cylinder rim 103 towards the piston rim 105 such that the stoppers 108,108’ are simultaneously pushed towards the first ends 110b, 110b’ of the slots 110,110’. The piston 104 is fully arranged within the cylinder 102 such that the PAV 1 is closed, thereby prohibiting fluid from passing therethrough, and hence prohibiting fluid from passing from the reservoir and through the outflow ports 2. The spring force shall be chosen such that the piston 104 is not moved below a limiting design pressure which may be around 170 bars (around 2500 psi).

If the design pressure is exceeded, i.e. applying an internal activation pressure to the piston 104 in the opposite direction of the force of the spring 106, the slots 110,110’ guide the stoppers 108,108’ from the first (closed) position P1, and hence the piston 104 to the second intermediate position P2 as shown in Fig. 4B and 5B. This occurs since the internal pressure applied on the piston 104 creates an applied force that exceeds the opposite force applied by the pretensioned spring 106. The spring 106 is hence further compressed and the stoppers 108,108’ are simultaneously guided within the paths of the slots 110,110’ in the direction circumferential and radial direction towards the first end 102a of the cylinder 102 until reaching the second ends 110b,110b’ of the slots 110,110’. The piston 104 is then arranged in the second position P2.

Further, the piston 104 may comprise a second piston rim 105’ at the first end section 104a of the piston 104 which may abut a second cylinder rim 103’ near the first end 102a of the cylinder 102. Such abutment between the piston 104 and the cylinder 102 allows the applied force to be spread over a larger area than if they were not present. Hence, the internal pressure executed on the stoppers 108,108’ of the piston 104 is spread to the cylinder 102 unloading some of the pressure executed on the stoppers 108,108’. A person skilled in the art will understand that instead of a rim 103 of the cylinder 102 the cylinder 102 may comprise any kind of resistance such as a retainer screw, retaining plug or the like.

As shown, the cylinder 102 has a smaller inner diameter at or near its first end 102a creating the second cylinder rim 103’ which abuts the second piston rim 105’ when the piston 104 is arranged in the second position P2.

The paths of the slots 110,110’ forces the stoppers 108,108’ of the piston 104 to move in a circumferential/radial path towards the first end 102a of the cylinder 102 when moving the piston from the first position P1 to the second position P2. Hence, the piston 104 is moved in the circumferential/rotational direction as well as in the longitudinal direction (i.e. in a partly helical path) until the stoppers 108,108’ reaches the second ends 110b,110b’ of the slots 110,110’. In this position the piston 104 is still fully arranged within the cylinder 102 such that the PAV 1 remains closed for fluid flow.

The activation pressure may for example be around 240 bars (3500psi) which is the internal pressure applied to the production string for activating mechanical packers.

As the internal pressure is reduced or removed, the piston 104 is moved due to the spring force until it reaches the open third position P3, shown in Fig. 4C and 5C. The stoppers 108,108’ of the piston 104 are moved in a straight longitudinal path of the slots 110,110’ towards second end 102b of the cylinder 102 until the stoppers 108,108’ are, due to the force exerted by the spring 106, pushed towards/abutting the third ends 110c,110c’ of the slots 110,110’. In this third position P3 of the piston 104, seal 113 of the piston 104 is extending outside the cylinder 102 such that the PAV 1 is open. Fluid is hence allowed to flow from the reservoir into the production string 10 via the PAV 1.

The spring force can be selected such that the spring 106 can be fully compressed when the piston 104 is in the second position P2 utilizing the spring 106 to a maximum. If the spring 106 is longer than the cylinder 102, the piston 104 will be tensioned in all positions after it is mounted along the production string 10. After release of the piston 104 into the third position P3, the piston 104 will still be tensioned, thereby preventing the PAV from closing due to internal pressures during operation such as backflow. However, the piston 104 may be fully extended having no tension at the third position P3 which also requires a force for moving the piston 104 back to the second position P2.

Further, the combined circumferential and longitudinal path of the slots 110,110’, which guide the piston 104 from the first position P1 to the second position P2, is hindering the stoppers 108,108’, when the piston 104 is arranged in the second position P2, to move back to the first position P1 when the internal pressure exerted on the piston 104 is released. The piston 104 will seek to move in a straight path, i.e. towards the third position P3. Hence the PAV 1 would be re-opened in the third position P3 after releasing the internal pressure and not closed in the first position, P1.

Further, the spring 106 can be free to rotate on one end so that torsional strain is not stored in the spring 106. Any torsion return motion may hence advantageously be smaller than the circumferential motion/rotation of the piston 104.

Claims

1. A system for preventing fluid to flow into a production string (10), wherein the system comprises

- a tubular production string (10) extending in a longitudinal direction, comprising

o a base wall (10a) and

o an outflow port (2) creating fluid communication through the base wall,

- a production string sleeve (11) surrounding the base wall across an longitudinal length (Lsleeve), wherein an inner surface of the production string sleeve and the outer surface of the base wall (10a) enclose a cavity (12) which includes the outflow port (2) and

- a pressure activated valve (1) arranged within the cavity (12), wherein the pressure activated valve (1) comprises

o a cylinder (102) comprising

o an open first longitudinal end (102b) and

o an open second longitudinal end (102a),

o wherein the cylinder (102) is arranged such that a closed flow path (13) is formed between the second longitudinal end (102a) and the outflow port (2),

o a hollow, cylindrical piston (104) moveably arranged within the cylinder (102), comprising

o an open first longitudinal end section (104b),

o a closed second longitudinal end section (104a) and

o a radially arranged opening (112) adjacent to the second longitudinal end section (104a),

o a seal (113) arranged to interact with the piston (104) and the cylinder (102) and

o a stopper (108,108’) fixed to the piston (104),

wherein the cylinder (102) further comprises a slot (110) for receiving and guiding the stopper (108,108’), wherein the slot (110) is configured to guide the piston (104)

from

i) a first position (P1), wherein the piston (104) is positioned in a pretensioned position by at least one spring (106), wherein the stopper (108) is abutting a first end (110a) of the slot (110) and wherein the piston (104) is arranged such that the at least one radially arranged opening (112) and the seal (113) are located within the cylinder (102), thereby hindering any fluid from flowing through the pressure activated valve (1);

towards

ii) a second position (P2) by compressing the at least one spring (106) due to an internal pressure exerted on the piston (104), wherein the piston (104) is moved in an at least partly helical path towards the second longitudinal end (102b) of the cylinder (102), until the stopper (108) is abutting a second end (110b) of the slot (110); and thereafter towards

iii) a third position (P3) by releasing the internal pressure exerted on the piston (104), wherein the piston (104) is moved in a path towards the second longitudinal end (102a) of the cylinder (102) until the stopper (108) abuts a third end (110c) of the slot (110) such that the at least one radially arranged opening (112) and the seal (113) are located outside the cylinder (102), allowing fluid to pass through the cylindrical piston (104).

2. The system according to claim 1, wherein the system comprises a plurality of outflow ports (2).

3. The system according to claim 1 or 2, wherein the cylinder (102) comprises two identical slots (110,110’) and the piston (104) comprises two stoppers (108,108’), wherein the two identical slots (110,110’) and the two stoppers (108,108’) are arranged on oppositely facing sides of the cylinder (102) and piston (104), respectively.

4. The system according to any one of the preceding claims, wherein the radially arranged opening (112) has one of

an oblong shape,

an oval shape, and

a rounded corner rectangular shape, and

wherein the radially arranged opening (112) extends in a longitudinal direction of the piston (104).

5. The system according to any one of the preceding claims, wherein the radially arranged opening (112) has a longitudinal length extending from any one of 5% to 60 % or 10% to 50% or 10% to 40% of a maximum longitudinal length of the piston (104).

6. The system according to any one of the preceding claims, wherein the radially arranged opening (112) has a circumferential extend of any one of 20 ̊ to 90 ̊ or 30 ̊ to 80 ̊ or 40 ̊ to 70 ̊.

7. The system according to any one of the preceding claims, wherein the piston (104) comprises a plurality of radially arranged openings (112).

8. The system according to any one of the preceding claims, wherein the piston (104) has a shorter longitudinal length than the cylinder (102).

9. The system according to any one of the preceding claims, wherein the seal (113) is arranged circumferentially at the second longitudinal end section (104a) to seal the piston (104) from the cylinder (102) when the piston (104) is in the first position (P1) or between the first position (P1) and second position (P2),.

10. The system according to any one of the preceding claims,

wherein the at least one spring (106) is arranged within at least one recess situated between the piston (104) and the cylinder (102) and

wherein one end of the at least one spring (106) abuts a first piston rim (105) of the piston (104) and an opposite end of the at least one spring (106) abuts a first cylinder rim (103) of the cylinder (102) arranged closer to the first longitudinal end (102b) of the cylinder (102) relative to the first piston rim (105).

11. The system according to claim 10,

wherein the longitudinal position of the first piston rim (105) is at or near the stopper (108,108’).

12. A method for preventing fluid flowing into a production string (10) using a system in accordance with any one of the preceding claims, wherein the method comprises the steps of:

- arranging the piston (104) of the pressure activated valve (1) in the closed first position (P1), wherein the piston (104) is exposed to a bias pressure set by the spring force from the at least one spring (106);

- exerting an internal pressure above the bias pressure from the at least one spring (106), wherein the internal pressure is exerted from the production string (10) towards the pressure activated valve (1) such that the piston (104) moves into the closed second position (P2); and

- releasing the internal pressure forcing the piston (104) to the open, third position, (P3).