Patent Description:
A production tubing system is installed in a hydrocarbon producing well with the main purpose of transporting oil/gas up to the topside of the well. Such a production tubing is also referred to as a completion string. Typically, the production tubing system is hung off in a tubing hanger and installed as one of the final steps before production can start.

The production tubing system must be pressure tested before production can start. One object of the present invention is to reduce the time required to install and test the production tubing system.

Some parts of the production tubing system may require well intervention operations, i.e. that equipment, tools etc. are lowered into the production tubing system for a specific purpose (for example to open a valve, to close a valve, to set a plug, to retrieve a plug etc).

Another object of the present invention is to reduce the amount of equipment needed to install and test the production tubing system and to avoid or reduce the number of well intervention operations. Patent documents <CIT> and <CIT> are prior art documents relevant to the present invention.

The present invention relates to a valve assembly for connection to an opening provided in a housing of a well tool device; where the valve assembly comprises:.

In one aspect, the predetermined threshold value is given by the biasing force of the biased flapper element. The predetermined threshold value is positive, i.e. the fluid pressure on the outside of the housing must be larger than the fluid pressure in the bore.

In one aspect, the flapper valve device comprises a flapper aligning body configured to be aligned in a predetermined position with respect to the housing, where the flapper element is pivotably connected to the flapper aligning body.

In one aspect, the flapper valve device comprises a spring device biasing the flapper element in relation to the flapper aligning body.

As the flapper aligning body is configured to be aligned in a predetermined position with respect to the housing, the spring device is also biasing the flapper element with respect to the housing when the valve assembly is connected to the opening of the housing.

In one aspect, the flapper aligning body comprises a pin opening, the flapper element comprises a pin opening and where the aligning body, the flapper element and the spring device is connected to each other by means of a pin fastener. The flapper element may be pivoted with respect to the flapper aligning body as long as the pivoting force is larger than the biasing force provided by the spring device.

In one aspect, the flapper element supporting device comprises a flapper element supporting body comprising a stop element for preventing the flapper element from protruding into the bore when the flapper element is in its open position.

In one aspect, the flapper element supporting body comprises a fluid guiding surface facing towards the flapper element.

In one aspect, the stop element is not protruding into the bore of the housing. Hence, fluid flow through the bore is not restricted by any parts of the valve assembly.

In addition, it is achieved intervention tools may pass through the bore without being restricted by any parts of the valve assembly.

In one aspect, the fluid communication channel has a longitudinal axis provided in parallel with the longitudinal axis of the valve assembly. In one aspect, the longitudinal axis of the valve assembly is perpendicular to the longitudinal axis of the housing of the well tool device.

In one aspect, the flapper element is oriented in parallel with the longitudinal axis of the housing. The flapper element is oriented with an angle α between <NUM>° - <NUM>° with respect to the longitudinal axis of the housing in the open position.

In one aspect, a rotation axis of the flapper element is perpendicular to the longitudinal axis of the housing. In one aspect, the rotation axis of the flapper element is also perpendicular to the longitudinal axis of the valve assembly. In one aspect, the rotation axis of the flapper element is provided in the upper part of the opening.

In one aspect, the aligning body and the flapper element supporting body are both generally U-shaped, where the ends of the generally U-shaped bodies are facing each other, thereby forming a substantially circular compartment forming a second part of the fluid communication channel.

In one aspect, there are two or more such stop elements, one in each end of the generally U-shaped flapper element supporting body. The fluid guiding surface may be provided between the two stop elements.

In one aspect, the securing device comprises a securing body having a flapper element facing surface facing towards the flapper element, the flapper element facing surface comprising a recess in which a sealing element is provided, where the flapper element is sealingly engaged towards the flapper element facing surface when the flapper element is in its closed state.

In one aspect, the securing body comprises a recess in which a sealing element is provided, where the sealing element is configured to prevent fluid flow through the opening radially outside of the securing body.

In one aspect, the sealing body comprises threads for securing the sealing body to threads provided in the opening. Alternatively, screws or other types of fasteners may be used to secure the sealing body to the opening of the housing.

In one aspect, the securing device comprises a filter to prevent debris from entering the fluid communication channel.

In one aspect, the filter is connected to the securing body by means of screws or other fasteners.

In one aspect, the bore is a through bore provided in the housing. The longitudinal center axis of the through bore may be aligned with the longitudinal center axis of the housing. Alternatively, the longitudinal center axis of the trough bore may be eccentric with regard to the longitudinal center axis of the housing.

In one aspect, the fluid communication between the outside of the housing and the bore is provided in a radial direction.

In one aspect, the well tool device may be a production tubing sub.

The present invention also relates to a production tubing sub for a production tubing system, where the production tubing sub comprises:.

In one aspect, the production tubing sub further comprises an axially displaceable sleeve configured to be displaced between a first sleeve position in which fluid flow through the valve assembly is allowed, and second sleeve position in which fluid flow through the valve assembly is prevented, even if the fluid pressure difference between the outside of the housing and the inside of the housing is larger than the predetermined fluid pressure threshold value.

In one aspect, the sleeve is provided radially inside of the valve assembly. Alternatively, the sleeve may be provided radially outside of the valve assembly.

The present invention also relates to a production tubing system for an oil and/or gas well, comprising:.

characterized in that the system further comprises:.

In one aspect, the production tubing sub is located in the production tubing below the packer assembly.

In one aspect, the system further comprises a second, upper valve located in the upper part of the production tubing.

In one aspect, the first, lower valve is fluid pressure actuated. In one aspect, the second, upper valve is fluid pressure actuated.

In one aspect, the first, lower valve has an initially closed state. The first lower valve can, when actuated, be brought to a permanently open state.

In one aspect, the second, upper valve has an initially open state. It can, when actuated, be brought to a temporarily closed state and then to a permanently open state.

The present invention also relates to a method for installing a production tubing system in a well, comprising the steps of:.

In one aspect, the method further comprises the step of:.

In one aspect, the step of allowing well fluid to enter the through bore is performed as long as the differential fluid pressure between the outside of the housing and the bore is above a predetermined threshold value.

In one aspect, the predetermined threshold value is given by the biasing force of the biased flapper element of the valve assembly.

Embodiments of the present invention will now be described in detail below, with reference to the enclosed drawings, wherein:.

It is now referred to <FIG>, in which a well W is shown with dashed lines. The wall of the well W typically comprises sections of subterranean formation, casing pipes C cemented to the subterranean formation etc..

Inside the well W, a production tubing system <NUM> is shown, comprising a production tubing or pipe <NUM>, typically comprising sections of pipe connected to each other. The production tubing <NUM> is hung off in a topside tubing hanger <NUM>. The production tubing <NUM> comprises a fluid bore <NUM> in which fluid/gas is transported up from the well W or down into the well W.

The production tubing system <NUM> further comprises a first or lower valve <NUM> provided in the lower part of the production tubing <NUM> and a second or upper valve <NUM> provided in the upper part of the production tubing <NUM>.

The production tubing system <NUM> further comprises a so-called packer assembly <NUM> located radially outside of the production tubing <NUM> and above the lower valve <NUM>. The packer assembly <NUM> seals off the so-called annulus A radially between the casing of the well W and production tubing <NUM> and hence prevents fluid flow in the direction of the production tubing up or down the annulus.

The production tubing system <NUM> further comprises an upper safety valve <NUM> located above or below the upper valve <NUM>. The safety valve <NUM> is typically referred to as a down hole safety valve or abbreviated DHSV.

It should be noted that in fig. 1a, the upper part of <FIG> is faced towards the topside of the well W, while the lower part of <FIG> is faced towards the bottom of the well. It should be noted that even though the production tubing <NUM> is oriented vertically in <FIG>, the lower parts of the production tubing may be inclined with respect to the vertical axis or the lower parts of the production tubing may even be horizontal. Hence, the terms "upper", "above" etc. should be interpreted as "closer to the topside of the well", while the terms "lower", "below", etc. should be interpreted as "closer to the bottom of the well".

The lower valve <NUM> will be shortly described. The lower valve <NUM> is closed in its initial state, but will be opened when oil/gas production is to start. The lower valve <NUM> is considered known per se, and may for example be a valve sold under the name Inter Remote Shatter Valve (IRSV) which is described in "<NPL>.

The upper valve <NUM> will now be shortly described. The upper valve <NUM> is initially open, but can be brought to a temporarily closed state before it is brought to a permanent open state when oil/gas production is to start. The upper valve <NUM> is considered known per se, and may for example be a valve like the one described in NO <NUM>. This valve is sold under the name Inter Remote Bypass Valve (IRBV).

The packer assembly <NUM> is also considered known per se.

It should be noted that the production tubing system <NUM> may comprise other types of lower and upper valves <NUM>, <NUM> than the examples described above. It should also be noted that the upper valve <NUM> is not essential for the system <NUM>.

The production tubing system <NUM> further comprises a production tubing sub <NUM> connected between two sections of production tubing <NUM>. The production tubing sub <NUM> will be described in detail below.

As shown in <FIG>, the production tubing sub <NUM> is located above the lower valve <NUM>, but below the packer assembly <NUM>.

It is now referred to <FIG>, and to the details of <FIG> shown in <FIG>. Here, the production tubing sub <NUM> is shown to comprise a housing <NUM> and a through bore <NUM> provided axially through the housing <NUM>. The longitudinal center axis of the housing <NUM> is shown as a dashed line L12. In the present embodiment, this dashed line L12 coincides with the longitudinal center axis of the bore <NUM>. It should be noted that in an alternative embodiment, the longitudinal center axis of the through bore <NUM> may be eccentric or parallel to the longitudinal center axis L12 of the housing <NUM>.

The housing <NUM> comprises upper and lower connection interfaces CI for connection to other production tubing strings. Typically, these are threaded connection interfaces.

The housing <NUM> further comprises a valve assembly <NUM> provided in an opening <NUM> in the housing <NUM> between an outside O of the housing <NUM> and the bore <NUM>.

The valve assembly <NUM> comprises a fluid communication channel <NUM> providing fluid communication from the outside O of the housing <NUM> to the bore <NUM>, as indicated by a dashed arrow in <FIG>.

In <FIG>, a longitudinal axis L20 of the valve assembly <NUM> is indicated as a dashed line. The longitudinal axis L20 is provided in a radial direction, i.e. perpendicular to the longitudinal center axis L12.

In <FIG>, the fluid communication channel <NUM> is open, as indicated by a dashed arrow <NUM>. In <FIG> the fluid communication channel <NUM> is closed, and no fluid flow is allowed between the bore <NUM> and the outside O.

It is now referred to <FIG>, which are exploded views of the valve assembly <NUM> seen from two different sides. Here, the different parts of the valve assembly <NUM> are separated into three main parts as indicated by dashed boxes. These main parts, comprising a flapper valve device <NUM>, a flapper element supporting device <NUM> and securing device <NUM> will be described in detail below. Then the installation of the valve assembly <NUM> to the production tubing sub <NUM> will be described, and finally the use of the production tubing system <NUM> with such a production tubing sub <NUM> will be described.

It is now referred to <FIG>. The flapper valve device <NUM> comprises a flapper aligning body <NUM> having a pin opening 31a. In addition, the flapper valve device <NUM> comprises a flapper element <NUM> having a pin opening 32a. The flapper element <NUM> is pivotably connected to the flapper aligning body <NUM> by means of a pin fastener <NUM> inserted through the pin openings 31a, 32a. The flapper aligning body <NUM> is configured to be aligned in a predetermined position with respect to the housing <NUM>. One way of achieving this is to provide the opening <NUM> in the housing <NUM> with a recess or supporting surface 16a adapted to the shape of the flapper aligning body <NUM> which will prevent movement of the flapper aligning body <NUM> with respect to the opening <NUM> of the housing <NUM>. This supporting surface 16a will be described further in detail below with respect to <FIG>.

As shown in the drawings, the flapper aligning body <NUM> is generally U-shaped.

In addition, the flapper device <NUM> comprises a coiled spring <NUM>, for biasing the flapper element <NUM> with respect to the flapper aligning body <NUM>. As the flapper aligning body <NUM> is configured to be aligned in a predetermined position with respect to the housing <NUM>, the spring device <NUM> is also biasing the flapper element <NUM> with respect to the housing <NUM> when the valve assembly <NUM> is provided in its position in the opening <NUM> of the housing <NUM>.

The main purpose of the flapper element supporting device <NUM> is to support the flapper element <NUM> when the flapper element <NUM> is in its open position.

In <FIG>, it is shown that the flapper element supporting device <NUM> comprises a flapper element supporting body <NUM> having two stop elements <NUM>. The flapper element supporting body <NUM> is generally U-shaped, where one stop element <NUM> is provided in each end of the generally U-shaped flapper element supporting body <NUM>.

The generally U-shaped flapper aligning body <NUM> and the generally U-shaped flapper element supporting body <NUM> have their respective ends faced towards each other, thereby forming a substantially circular compartment 23b, as shown in <FIG>. In <FIG>, this substantially circular compartment 23b is indicated as a dashed circle.

The flapper element supporting body <NUM> is, similar to the body <NUM>, configured to be aligned in a predetermined position with respect to the housing <NUM>. One way of achieving this is to provide the opening <NUM> in the housing <NUM> with a recess or supporting surface 16b adapted to the shape of the flapper element supporting body <NUM> which will prevent movement of the flapper element supporting body <NUM> with respect to the opening <NUM> of the housing <NUM>. This supporting surface 16b will be described further in detail below with respect to <FIG>.

In the area between the stop elements <NUM>, the flapper element supporting body <NUM> comprises a fluid guiding surface <NUM> (<FIG>) facing towards the flapper element <NUM> and hence towards the substantially circular compartment 23b.

It should be noted that the flapper element supporting body <NUM> may comprise one or more than two such stop elements <NUM>. In the present embodiment, the body <NUM> and the stop elements <NUM> are provided as one body. It should be noted that in alternative embodiments, the flapper element supporting device <NUM> may comprise the body <NUM> and stop elements <NUM> as separate elements connected to each other.

The securing device <NUM> will now be described with reference to <FIG>, <FIG>and <FIG>, where it is shown that the securing device <NUM> comprises a securing body <NUM>. The securing body <NUM> is substantially cylindrical, where the axis L20 indicates the longitudinal axis of the cylindrical securing body <NUM>. The securing body <NUM> comprises a through bore indicated as 23a in parallel with the axis L20.

The securing body <NUM> comprises first end surface, hereinafter referred to as a flapper element facing surface <NUM> faced towards the flapper element <NUM>. In the present embodiment, the flapper element facing surface <NUM> forms a plane perpendicular to the axis L20. When the valve assembly <NUM> is installed in the opening <NUM> of the housing, as shown in <FIG>, the flapper element facing surface <NUM> is also facing inwardly towards the bore <NUM> of the housing <NUM>.

The securing body <NUM> further comprises a circular recess <NUM> provided in the flapper element facing surface <NUM> surrounding the bore 23a, as shown in <FIG>.

The securing body <NUM> further comprises a second end surface <NUM> provided in the opposite end of the first end surface <NUM>. The second end surface <NUM> comprises a tool connection interface <NUM> in the form of four circular grooves provided in the second end surface <NUM>.

The securing body <NUM> further comprises a threaded surface <NUM> provided circumferentially around the outside of the securing body <NUM>. The threaded surface <NUM> is adapted to be secured to a correspondingly threaded surface provided in the opening <NUM>.

Between the threaded surface <NUM> and the flapper element facing surface <NUM>, the securing body <NUM> comprises a circular recess <NUM> circumferentially around the outside of the securing body <NUM>.

The securing device <NUM> comprises a first sealing element <NUM> provided in the recess <NUM> and a second sealing element <NUM> provided in the recess <NUM>.

The purpose of the first sealing element <NUM> is to provide a seal between the flapper element facing surface <NUM> and the flapper element <NUM> when the flapper element <NUM> is in the closed position. The purpose of the second sealing element <NUM> is to provide a seal between the securing body <NUM> and the housing <NUM>, i.e. to prevent fluid flow through the opening <NUM> radially outside of the securing body <NUM>.

In the present embodiment, the securing device <NUM> comprises a filter <NUM> to prevent debris from entering the fluid communication channel <NUM>. The filter <NUM> is connected to the second end surface <NUM> by means of screws or other fasteners <NUM>. In the present embodiment, the filter <NUM> comprises a mesh with <NUM> x <NUM> openings. It should be noted that the valve assembly <NUM> may be used with other types of filters and also without any filter.

The installation of the valve assembly <NUM> to the opening <NUM> of the housing <NUM> of the well tool device <NUM> will now be described. The well tool device <NUM> is here a production tubing sub shown in <FIG>. However, the well tool device <NUM> may also be used in other types of well tool devices.

As described above, the valve assembly <NUM> comprises three main parts; the flapper valve device <NUM>, the flapper element supporting device <NUM>, and the securing device <NUM>.

Details of the opening <NUM> will now be described with reference to <FIG>.

The opening <NUM> comprises a first supporting surface 16a shaped to receive and support the flapper aligning body <NUM> and a second supporting surface 16b shaped to receive and support the flapper element supporting body <NUM>. The opening <NUM> further comprises two spacer elements 16c protruding towards the center axis L20 of the valve assembly L20, which in the present embodiment is substantially similar to the center axis of the opening <NUM>.

Hence, the supporting surfaces 16a, 16b and the spacer elements 16c together form two recesses, one for each of the bodies <NUM>, <NUM>.

In <FIG>, it is shown that there is an area having a distance D31-<NUM> between the first and second bodies <NUM>, <NUM>. When the valve assembly <NUM> is installed in the opening <NUM> of the sub, the spacer element 16c will be located in this area between the first and second bodies <NUM>, <NUM>. Hence, the spacer element 16c also forms a part of the circular compartment 23b as shown in <FIG>.

First, the flapper element supporting device <NUM> is inserted in the opening <NUM> into contact with the second supporting surface 16b. Then, the flapper valve device <NUM> is inserted in the opening <NUM> into contact with the first supporting surface 16a.

In a final step, a tool (not shown) and the tool connection interface <NUM> are used to screw the securing device <NUM> into the opening <NUM> and hence connect the threads <NUM> to the threads of the opening <NUM>.

Consequently, the securing device <NUM> is used to secure the devices <NUM>, <NUM> to the opening <NUM> in an easy and effective way. An alternative, but more complex solution, would be to use separate fasteners to secure the devices <NUM>, <NUM> to the opening <NUM>, before the securing device <NUM> is secured to the opening <NUM>.

It is now referred to <FIG>, where it is shown that the flapper element <NUM> is sealingly engaged towards the sealing element <NUM> and the flapper element facing surface <NUM>. The flapper element <NUM> here preferably oriented in parallel with the longitudinal axis L12 of the housing <NUM>, as indicated by an angle α = <NUM>° between the flapper element facing surface <NUM> and the flapper element <NUM>.

It is now referred to <FIG>, where it is shown that the flapper element <NUM> is engaged or supported towards the stop elements <NUM> of the flapper element supporting body <NUM>. The angle α between the flapper element facing surface <NUM> and the flapper element <NUM> is here shown to be ca <NUM>°. However, other angles are possible, the angle α may be in the range <NUM>° - <NUM>°. Two of the factors for determining how large the angle α may be, is the housing thickness T12 indicated in <FIG> and of course the size of the flapper element <NUM> needed to prevent fluid flow through the bore 23a.

A rotation axis R32 of the flapper element <NUM> is indicated in <FIG>. This rotation axis R32 is perpendicular to the longitudinal axis L12 of housing <NUM>. Preferably, the rotation axis R32 of the flapper element <NUM> is also perpendicular to the longitudinal axis L20 of the valve assembly <NUM>. In one aspect, the rotation axis R23 of the flapper element <NUM> is provided in the upper part of the opening <NUM>, i.e. closer to the topside of the well than the bottom of the well.

In <FIG>, the bore <NUM> of the housing <NUM> is indicated as a dashed line. As shown here, the stop elements <NUM> are preventing the flapper element <NUM> from protruding into the bore <NUM> when the flapper element <NUM> is in its open position. In addition, the stop elements <NUM> are not protruding into the bore <NUM> of the housing <NUM>. Hence, fluid flow through the bore <NUM> is not restricted by any parts of the valve assembly <NUM>. Moreover, it is achieved that intervention tools may pass through the bore <NUM> without being restricted by any parts of the valve assembly <NUM>.

In <FIG>, it is also shown that the fluid communication channel <NUM> through the valve assembly <NUM> is formed by two parts, the first part being the bore 23a through the securing element <NUM> and the second part being the substantially circular compartment 23b formed between the two substantially U-shaped bodies <NUM>, <NUM>.

The fluid flow from the outside O and into the bore <NUM> via the bore 23a is deflected by the flapper element <NUM> in the compartment 23b. The fluid will follow the dashed line in <FIG> and <FIG>, i.e. through the bore 23a, through the compartment 23b and out between the flapper element <NUM> and the fluid guiding surface <NUM> and further into the bore <NUM>.

By means of this design, in particular to the circular bore 23a and the substantially circular compartment 23b, the risk for debris etc. to accumulate is reduced. Consequently, the risk for such debris to obstruct the movement of the flapper element <NUM> is reduced.

As described above, the flapper element <NUM> is biased to the closed position by means of a biasing force provided by the spring device <NUM>. The flapper element <NUM> is configured to be brought from its closed position to its open position when a force created by the differential fluid pressure between the outside O of the housing <NUM> and the bore <NUM> is above a predetermined threshold value Pthreshold, where this predetermined threshold value is given by the biasing force of the biased flapper element <NUM>. More specifically, the flapper element <NUM> may be pivoted with respect to the flapper aligning body <NUM> as long as the pivoting force is larger than the biasing force provided by the spring device <NUM>.

The predetermined threshold value is positive, i.e. the fluid pressure on the outside O of the housing <NUM> must be larger than the fluid pressure in the bore <NUM> to bring the flapper element <NUM> from the closed position to the open position.

The production tubing sub is used during the installation of a production tubing system <NUM> in a well. This will be described in detail below with reference to <FIG>.

It is now referred to <FIG>. Here the production tubing system <NUM> for the oil and/or gas well W is shown. A production tubing <NUM> has a through bore <NUM> in its longitudinal direction I, where the production tubing <NUM> is hung off by means of a tubing hanger <NUM>.

The system <NUM> comprises an upper safety valve <NUM> located in the upper part of the production tubing <NUM>, a lower valve <NUM> located in the lower part of the production tubing <NUM> and a packer assembly <NUM>. The packer assembly is provided for closing an annulus A outside of the production tubing <NUM> above the lower valve <NUM>. The annulus A here corresponds to the outside O shown in <FIG>.

The system <NUM> further comprises a production tubing sub <NUM> with one or more valve assemblies <NUM>. The production sub <NUM> is connected to the production tubing <NUM> above the lower valve <NUM> and below the packer assembly <NUM>.

Optionally, the production tubing system <NUM> may also comprise an upper valve <NUM> located in the upper part of the production tubing <NUM>.

The lower valve <NUM> is initially closed. The upper valve <NUM> and the safety valve <NUM> are both open.

No fluid will be added into the tubing string <NUM> from the topside as the tubing string is lowered into the well. Hence, as the tubing string is moved downwardly, the fluid pressure outside of the tubing string <NUM> will be higher than the fluid pressure inside of the tubing string. Hence, the fluid pressure difference will bring the valve assembly to its open state and fluid will enter the tubing string. Hence, one advantage of the production tubing sub <NUM> is that it enables self-filling during installation of the production tubing system <NUM>.

In <FIG>, is also possible to use the production tubing sub <NUM> to circulate fluid, for example to replace one well fluid with a different well fluid, for example to replace a light fluid with a heavier fluid for well control purposes etc. This is done by pumping the new fluid down the annulus A and receive the previous fluid up through the tubing string.

When the tubing string has been held in the desired position for a while, the pressure inside the tubing will be substantially equal to the fluid pressure outside of the tubing string and the valve assembly will close due to the biased flapper element <NUM>.

Alternatively, the fluid inside of the tubing string <NUM> is increased relative to the annulus fluid pressure by means of a pumping device etc., thereby closing the valve assembly <NUM>.

The fluid pressure is now increased further, to set the fluid pressure actuated packer assembly, as shown in <FIG>.

In prior art, a well intervention operation is normally necessary here, to set/retrieve a plug in the lower end of the tubing string. However, as the lower plugging device <NUM> is closed and the production tubing sub <NUM> allows flow in one direction only, this well intervention operation is no longer needed.

The integrity of the set packer assembly <NUM> may now be tested by increasing the pressure in the annulus A above the packer assembly. If the packer assembly is leaking, this will cause the fluid pressure below the packer assembly <NUM> to increase. This again will cause the valve assembly <NUM> to open, and fluid will exit from the top of the production tubing. If the packer assembly <NUM> is not leaking, no fluid will exit from the top of the production tubing.

As the volume of the well W below the packer assembly <NUM> can be limited/small it can be difficult to know that the packer assembly is holding the pressure. Hence, to verify that it actually is the packer assembly that is tested (and not the closed well volume below the packer assembly), this test of packer assembly is considered more reliable and efficient.

After the testing of the packer assembly, the lower valve <NUM> can be brought to a permanently open state by means of fluid pressure pulses, and production may start.

After the packer assembly is set and the well is tested the upper valve <NUM> can be closed. It can act as a shallow barrier enabling removal of BOP. After x-mas tree is installed the upper valve <NUM> can be opened and production may start.

It is now referred to <FIG>. Here, the well tool device <NUM> comprises an axially displaceable sleeve <NUM>, which may be used to prevent fluid flow through the valve assembly <NUM> even if the fluid pressure difference between the outside of the housing and the inside of the housing is larger than the predetermined fluid pressure threshold value.

Hence, prior to closing the sleeve <NUM>, the sub <NUM> can be used for self-filling and/or circulation purposes, as described above.

In addition, when the sleeve <NUM> is (permanently) closed it can be used as a barrier between the annulus and the bore of the tubing.

Claim 1:
A valve assembly (<NUM>) for connection to an opening (<NUM>) provided in a housing (<NUM>) of a well tool device (<NUM>); where the valve assembly (<NUM>) comprises:
- a flapper valve device (<NUM>) comprising a flapper element (<NUM>); where the flapper element (<NUM>) is biased to a closed position;
- a flapper element supporting device (<NUM>) for supporting the flapper element (<NUM>) when the flapper element (<NUM>) is in its open position;
- a securing device (<NUM>) for securing the flapper valve device (<NUM>) and the flapper element supporting device (<NUM>) to the opening (<NUM>); where the securing device (<NUM>) comprises a through bore (23a) forming a first part of the fluid communication channel (<NUM>)
characterized in that the valve assembly (<NUM>) further comprises:
- a fluid communication channel (<NUM>) providing fluid communication from an outside (O) of the housing (<NUM>) to a bore (<NUM>) provided on the inside of the housing (<NUM>);
wherein the flapper element (<NUM>) is configured to be in the closed position in which the fluid communication channel (<NUM>) is closed and an open position in which the fluid communication channel (<NUM>) is open;
wherein the flapper element (<NUM>) is configured to be brought from its closed position to its open position when a force created by the differential fluid pressure between the outside (O) of the housing (<NUM>) and the bore (<NUM>) is above a predetermined threshold value.