Abstract:
A self-adjustable valve or flow control device for controlling the flow of a fluid from one space or area to another by exploiting the Bernoulli principle, to control the flow of fluid, such as oil and/or gas including any water, from an oil or gas reservoir and into a production pipe of a well in the oil and/or gas reservoir, from an inlet port on an inlet side to an outlet port on an outlet side of the device. The valve includes a movable valve body arranged to be acted on by a temperature responsive device. The valve body is arranged to be actuated towards its closed position by the temperature responsive device in response to a predetermined increase in temperature in the fluid surrounding and/or entering the valve. The temperature responsive device includes an expandable device including a sealed structure at least partially filled with an expandable material

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a temperature responsive autonomous valve arrangement and method. The valve may for example be used for achieving constant mass flow of hydrocarbons into a production line in a wellbore. 
       BACKGROUND ART 
       [0002]    Devices for recovering of oil and gas from long, horizontal and vertical wells are known from U.S. Pat. Nos. 4,821,801, 4,858,691, 4,577,691 and GB patent publication No. 2169018. These known devices comprise a perforated drainage pipe with, for example, a filter for control of sand around the pipe. A considerable disadvantage with the known devices for oil/and or gas production in highly permeable geological formations is that the pressure in the drainage pipe increases exponentially in the upstream direction as a result of the flow friction in the pipe. Because the differential pressure between the reservoir and the drainage pipe will decrease upstream as a result, the quantity of oil and/or gas flowing from the reservoir into the drainage pipe will decrease correspondingly. The total oil and/or gas produced by this means will therefore be low. With thin oil zones and highly permeable geological formations, there is further a high risk that of coning, i. e. flow of unwanted water or gas into the drainage pipe downstream, where the velocity of the oil flow from the reservoir to the pipe is the greatest. 
         [0003]    When extracting oil from reservoirs by injection of steam or using combustion, the differential pressure can vary along the drainage pipe. This may cause problems should injected steam or combustion gas reach the valves used for draining fluid from the reservoir into the production pipe, as many such valves are not able to close to prevent steam or combustion gas from entering the production pipe. In particular, if the differential pressure is relatively low, ingress of steam or combustion gas can lead to a “short circuit” of the injection pressure and the production pressure. This will cause the differential pressure to drop even further, which has a negative effect on the efficiency of the drainage process (injected energy vs. produced oil volume). 
         [0004]    A further result of areas with low pressure differential combined with high temperature, or hot spots, is that fluid with low viscosity from high temperature regions of the reservoir will dominate the inflow into the production pipe. In this way, the production pipe will have an undesirable inflow profile along its length. 
         [0005]    From World Oil, vol. 212, N. 11 (November 1991), pages 73-80, is previously known to divide a drainage pipe into sections with one or more inflow restriction devices such as sliding sleeves or throttling devices. However, this reference is mainly dealing with the use of inflow control to limit the inflow rate for up hole zones and thereby avoid or reduce coning of water and or gas. 
         [0006]    WO-A-9208875 describes a horizontal production pipe comprising a plurality of production sections connected by mixing chambers having a larger internal diameter than the production sections. The production sections comprise an external slotted liner which can be considered as performing a filtering action. However, the sequence of sections of different diameter creates flow turbulence and prevents the running of work-over tools operated along the outer surface of the production pipe. 
         [0007]    Devices as disclosed in WO2009/088292 and WO 2008/004875 are robust, can withstand large forces and high temperatures, can prevent draw downs (variations in differential pressure), need no energy supply, can withstand sand production, yet are reliable, simple and very cheap. However, several improvements might nevertheless be made to increase the performance and longevity of the above device in which many of the different embodiments of WO2009/088292 and WO 2008/004875 describe a disc as the movable body of the valve. 
         [0008]    When extracting oil and or gas from geological production formations, fluids of different qualities, i.e. oil, gas, water (and sand) is produced in different amounts and mixtures depending on the property or quality of the formation. None of the above-mentioned, known devices are able to distinguish between and control the inflow of oil, gas or water on the basis of their relative composition and/or quality. In particular, the known devices are not able to perform a satisfactory control of variations in inflow into the production pipe due to variations of differential pressure caused by temperature variations. WO 2008/004875 does disclose a temperature responsive valve, but the suggested solution involves bending the movable valve body by means of a bi-metallic element. The suggested solution is relatively complex and requires an expensive valve body that is susceptible to wear caused by repetitive deformation. WO 2005/103443 discloses a temperature responsive valve where the material of a valve body has a linear expansion coefficient that is greater than that of the well pipe material. When the temperature increases, the valve body expands more than the well pipe and moves in the direction of its closed position covering the opening. This solution will give a relatively long response time, causing large quantities of gas and/or hot liquid to enter the drainage pipe to disturb the flow through the drainage pipe. 
         [0009]    The present invention provides an improved valve arrangement which aims to minimize problems relating to variations in inflow into the production pipe due to temperature variations. 
       SUMMARY OF THE INVENTION 
       [0010]    The invention provides a self-adjustable valve and method as set out in the accompanying claims. 
         [0011]    The present invention is preferably provided an inflow control device, or valve, which is self adjusting or autonomous. The invention can also be adapted to other types of controllable valves suitable for this purpose. A common feature for the valves according to the invention is the ability to automatically close the valve and prevent inflow into a production pipe in response to an increase in temperature of the fluid surrounding and/or entering the valve arrangement. The inflow control devices can easily be fitted in the wall of a production pipe and allows the use of work-over tools. The device is designed to “distinguish” between the oil and/or gas and/or water and is able to control the flow or inflow of oil or gas, depending on which of these fluids such flow control is required. 
         [0012]    According to a preferred embodiment, the invention relates to a self-adjustable valve or flow control device controlling the flow of a fluid from one space or area to another by exploiting the Bernoulli principle, in order to control the flow of fluid, i.e. oil and/or gas including any water, from a reservoir and into a production pipe of a well in the oil and/or gas reservoir. The production pipe can comprise a lower drainage pipe preferably being divided into one or more sections each including one or more inflow control devices which allow fluid communication between the geological production formation and the interior flow space of the drainage pipe. Fluid can flow between an inlet port on an inlet side, facing the formation, to an outlet port on an outlet side of the device, facing the interior of the production pipe. The valve further comprises a movable valve body arranged to be acted on by a temperature responsive device. The valve body is arranged to be actuated towards its closed position by the temperature responsive device in response to a predetermined increase in temperature in the fluid surrounding and/or entering the valve. 
         [0013]    The temperature responsive device may comprise a sealed expandable means at least partially filled with a material that is arranged to undergo a significant expansion when the temperature in the fluid surrounding the device increases. Preferably, the expansion should be sufficient to substantially or fully close the valve when the temperature in the fluid surrounding the temperature responsive device increases above a predetermined value. Such an expansion can, for instance, be achieved by selecting a material that undergoes a phase change at a predetermined temperature. An example of such a phase change is a liquid which will boil at or above a predetermined temperature. The fluid material is selected dependent on where the production pipe is located. For instance, a production pipe located at a depth of 300 metres can be subjected to pressures of 25-30 bar and temperatures of 250-290° C. during normal production conditions. In order to prevent a sudden influx of steam having a higher temperature through the valve, the expandable means can be filled with an alcohol-water mixture that boils at e.g. 280° C. During an undesirable increase of temperature in the fluid flowing through the valve, the expandable means is arranged to expand and cause a displacement of the movable valve body towards its closed position when the temperature of the fluid exceeds said predetermined temperature. In this way, the valve can be closed to prevent boiling or flashing water from entering the production pipe. Flashing or boiling can occur when the differential pressure across the inflow control device is relatively low. If boiling or flashing water is allowed to enter the production pipe, then this causes a “short circuit” of the injection pressure and the production pressure and causes the differential pressure to drop further. This has a negative effect on the efficiency of the drainage process, as outlined above. Other undesirable fluids that can be prevented from entering the production pipe are hot production gases or combustion gases used for increasing the production rate. 
         [0014]    In order to control the opening and closing of the valve with varying temperatures, the expandable means may be arranged in contact with the fluid surrounding the production pipe or flowing through the valve. 
         [0015]    According to a first example, the expandable means is arranged in a fluid chamber in the valve, which chamber contains the movable valve body controlling the fluid flow through the valve. This example will typically be used for autonomous valves comprising a chamber containing a movable valve body in the form of a flat circular disc or a conical body with a flat base. The position of the movable valve body is normally controlled by an inflow of fluid from an inlet located facing the centre of the movable valve body and flowing radially outwards over at least a portion of the movable valve body and towards an outlet. An example of such a movable valve body or disc is shown in WO 2008/004875 A1 and will be described in further detail below. In this example, the expandable means is located on the opposite side of the disc relative to the fluid inlet. The expandable means can be attached to a portion of the fluid chamber and expandable into contact with the movable valve body. Alternatively, the expandable means can be attached to the movable valve body and expandable into contact with fluid chamber. 
         [0016]    When an undesirable increase of temperature in the fluid flowing through the valve occurs, heat is transferred by the hot fluid to the expandable means, partially through the movable valve body and partially around the outer edges thereof to the space between the chamber and the movable valve body where the expandable means is located. If the expandable means contains a fluid, the said fluid will undergo a phase change and begin to boil when the fluid flowing through the valve exceeds a predetermined temperature. This causes the expandable means to expand due to the increase in pressure and volume inside said expandable means. As the expandable means expands it will displace the movable valve body towards its closed position and, if the temperature increase is sufficient, eventually close the valve. 
         [0017]    According to a second example, the expandable means is arranged in a fluid conduit in series with the fluid flow through a valve. In this example, the expandable means is located in a conduit through which the entire or a part of the fluid flow passes, before passing through the valve to be controlled. The expandable means is directly or indirectly connected to a movable valve body or to an actuator controlling said valve, in order to act on said valve body to close the valve. As the expandable means expands it will urge the movable valve body towards its closed position and, if the temperature increase is sufficient, eventually close the valve. 
         [0018]    According to a third example, the expandable means is arranged in a fluid conduit in parallel with the main fluid flow through a valve. In this example, the expandable means is located in a conduit through which a part of the fluid flow passes, which partial flow bypasses the valve to be controlled. The expandable means is directly or indirectly connected to a movable valve body or to an actuator controlling said valve, in order to act on said valve body to close the valve. As the expandable means expands it will urge the movable valve body towards its closed position and, if the temperature increase is sufficient, eventually close the valve. 
         [0019]    According to one embodiment, the expandable means contains a fluid having a lower boiling point than a hot fluid, such as water, at the pressure in the reservoir surrounding the production pipe. As indicated above, the said fluid will undergo a phase change and begin to boil when the hot fluid from the formation flows through the valve inlet and past the expandable means exceeds a predetermined temperature. The increase in gas pressure inside the expandable means, caused by the evaporating fluid, will in turn cause an increase in volume of expandable means. This will result in a displacement of a movable valve body in contact with or acted directly or indirectly on by the expandable means. The fluid can comprise a suitable alcohol, an alcohol/water mixture or acetone. The fluid is selected depending on its boiling point at a predetermined pressure, which pressure is dependent on the pressure acting on the production pipe at the location of the valve, or inflow device. The properties of the material selected determines the rate at which the valve can be closed. In this way. the use and the desired reaction speed of the autonomous valve may determine which material used. 
         [0020]    The expandable means can be a sealed container at least partially filled with a fluid material. The container can have a predetermined general shape with at least a portion being resiliently deformable, or be in the form of a bag with a non-specified shape, which container is arranged to expand in a predetermined direction with increasing temperatures. The container can have a predetermined basic shape, such as a cylinder, with corrugated or undulating sides extending around its circumference to allow expansion in a predetermined direction. In the case of a valve with a movable valve body in the form of a disc located in a chamber, the end surfaces of the cylinder may be arranged to contact the movable valve body and the chamber, respectively. The cylinder can then be operated as a bellows arranged to expand in a predetermined direction. 
         [0021]    Alternatively the expandable means can be a sealed flexible or resilient container such as a bag. Such a resilient container can have a substantially shapeless form, arranged to expand in all directions. When heated above said predetermined temperature, the container is arranged to expand uniformly until constricted between a fixed surface and a component to be displaced. In the case of a valve with a movable valve body in the form of a disc located in a chamber, the container will be constricted by a chamber wall and the disc. Further expansion of the container causes displacement of disc. A flexible or resilient container of this type can also have at least one reinforced portion to facilitate attachment of the container. A further reinforced portion can be provided to ensure contact between the expanding portion of the container and the movable valve body or actuator to be displaced. 
         [0022]    As indicated above, the container making up the expandable means can be attached to a portion of the fluid chamber and expandable into contact with a movable valve body. Alternatively, the expandable means can be attached to the movable valve body and expandable into contact with a wall in the fluid chamber. These alternatives are preferable for containers having a basic shape, with a predetermined direction of expansion. According to a further alternative, the expandable means can be held in a desired position by locating means on the movable valve body or the chamber wall, without being physically attached to either component. This alternative is preferable for containers having a substantially shapeless form, which can expand uniformly in all directions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Embodiments of the invention will now be described in detail, by way of example only, with reference to the attached figures. It is to be understood that the drawings are designed solely for the purpose of illustration and are not intended as a definition of the limits of the invention. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to schematically illustrate the structures and procedures described herein. 
           [0024]      FIG. 1  shows an autonomous valve arrangement provided with a flow control device according to the invention; 
           [0025]      FIG. 2A  shows a cross-section through a first valve arrangement; 
           [0026]      FIG. 2B  shows a cross-section through a second valve arrangement; 
           [0027]      FIG. 3A  shows a valve arrangement as shown in  FIG. 2A  provided with a heat expandable means according to a first embodiment of the invention; 
           [0028]      FIG. 3B  shows a valve arrangement as shown in  FIG. 2B  provided with a heat expandable means according to a second embodiment of the invention; 
           [0029]      FIG. 4  shows a valve arrangement provided with a heat expandable means according to a third embodiment of the invention; and 
           [0030]      FIG. 5  shows a valve arrangement provided with a heat expandable means according to a fourth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  shows a production pipe  11  provided with an opening in which an autonomous valve arrangement  12  according to the invention. The valve arrangement  12  is particularly useful for controlling the flow of fluid from a subterranean reservoir and into a production pipe  11  of a well in the oil and/or gas reservoir, between an inlet port  13  on an inlet side to at least one outlet port (not shown) on an outlet side of the autonomous valve arrangement  12 . The component part making up the entire autonomous valve arrangement is subsequently referred to as a “valve arrangement”, while the active components required for controlling the flow are commonly referred to as a “flow control device”. The inlet side of the autonomous valve arrangement  12  is located in the opening on the outer side  14  of the production pipe  11 , while the outlet side is located on the inner side  15  of the production pipe  11 . In the subsequent text, terms such as “inner” and “outer” are used for defining positions relative to the inner and outer surface of the valve arrangement when mounted in a pipe  11  (see  FIG. 1 ). A valve suitable for use in the embodiments referred to in this first example can be of the type described in the published application WO 2008/004875 or in the filed international application PCT//EP2011/050471. 
         [0032]      FIG. 2A  shows a cross-section through a valve arrangement  12   a  as described in WO 2008/004875. The device consists of first disc-shaped housing body  21  with an outer cylindrical segment  22  and inner cylindrical segment  23  and with a central hole or inlet port  13   a  and a second disc-shaped holder body  24  with an outer cylindrical segment  25 , as well as a preferably flat disc or freely movable valve body  26  provided in an open recess or chamber  27  formed between the first  21  and second  24  disc-shaped housing and holder bodies. The valve body  26  may for particular applications and adjustments depart from the flat shape and have a partly conical or semicircular surface facing the inlet port  13   a.  As can be seen from the figure, the cylindrical segment  25  of the second disc-shaped holder body  24  fits within and extends in the opposite direction of the outer cylindrical segment  22  of the first disc-shaped housing body  21  thereby forming a flow path as shown by the arrows A, where the fluid enters the control device through the central hole or inlet port  13   a  and flows towards and radially along the disc  26  before flowing through an annular opening  28  formed between the cylindrical segments  23  and  25  and further out through the annular opening, or outlet port  29  formed between the cylindrical segments  22  and  25 . In  FIG. 2A  the right hand side of the outlet port  29  appears to be blocked off, but this is only because the cross-section is taken at a position where there is a solid supporting portion (which is one of three such supporting portions) between the cylindrical segments  22  and  25 . Therefore the outlet port  29  is not blocked, and is indeed annular. In a later version of this valve there are no such supporting portions, and the outlet port  29  is open all the way around. The two disc-shaped housing and holder bodies  21 ,  24  are attached to one another by a screw connection, welding or other means (not shown in the figure). The entire valve assembly is removably mounted in an opening through a production pipe by means of a threaded connection indicated in  FIG. 2A . 
         [0033]    In operation, the inlet port  13   a  is connected to the recess  27  by a central aperture or opening, wherein the fluid is arranged to flow into the recess  27  through the central aperture from the formation. The fluid is then arranged to flow out of the recess  27  radially across a portion of a first surface  26   a  of the valve body, said first surface facing the inlet port  13   a,  and through an annular opening  28  in said valve body towards an annular outlet port  29 . 
         [0034]    The present invention exploits the effect of Bernoulli teaching that the sum of static pressure, dynamic pressure and friction is constant along a flow line: 
         [0000]    
       
         
           
             
               
                 
                   
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         [0035]    With reference to the valve shown in  FIG. 2A , when subjecting the movable valve body or disc  26  to a fluid flow, which is the case with the present invention, the pressure difference over the disc  26  can be expressed as follows: 
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         [0036]    Due to lower viscosity, a fluid such as gas will flow faster along the disc towards the outlet. This results in a reduction of the pressure on the area A2 above the disc while the pressure acting on the area A3 below the disc  28  remains static. As the disc  26  is freely movable within the recess it will move upwards and thereby narrow the flow path between the disc  26  and the first surface  26   a  of the recess  26 . Thus, the disc  26  moves downwards or upwards depending on the viscosity of the fluid flowing through, whereby this principle can be used to control the flow of fluid through of the device. 
         [0037]    Further, the pressure drop through a traditional inflow control device (ICD) with fixed geometry will be proportional to the dynamic pressure: 
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         [0038]    where the constant, K is mainly a function of the geometry and less dependent on the Reynolds number. In the control device according to the present invention the flow area will decrease when the differential pressure increases, such that the volume flow through the control device will not, or nearly not, increase when the pressure drop increases. Hence, the flow-through volume for the present invention is substantially constant above a given differential pressure. This represents a major advantage with the present invention as it can be used to ensure a substantially constant volume flowing through each section for the entire horizontal well, which is not possible with fixed inflow control devices. 
         [0039]    When producing oil and gas the flow control device according to the invention may have two different applications: Using it as inflow control device to reduce inflow of water or gas, or to maintain a constant flow through the flow control device. When designing the control device according to the invention for the different applications, such as constant fluid flow, the different areas and pressure zones will have impact on the efficiency and flow through properties of the device. The different area/pressure zones (indicated in  FIG. 2A ) may be divided into:
   A1, P1 is the inflow area and pressure respectively. The force (P1*A1) generated in the inlet port  13   a  by this pressure will strive to open the control device (move the disc or body  28  downwards).   A2, P2 is the area and pressure in the zone between the first surface  26   a  of the disc and the recess  27 , where the velocity will be largest and hence represents a dynamic pressure source. This area is located between the inlet port  13   a  and the annular opening  28  out of the recess  27 . The resulting dynamic pressure will strive to close the control device by moving the disc or body  26  upwards as the flow velocity increases and the pressure is reduced.   A3, P3 is the area and pressure at the annular opening  28  out of the recess  27 . The pressure should be the same as the well pressure (inlet pressure).   A4, P4 is the area and pressure behind the movable disc or body  26 , between a second surface  26   b  (opposite the first surface  26   a ) of the disc  26  and the recess  27 . The pressure behind the movable disc or body should be the same as the well pressure (inlet pressure). This will strive to move the body upwards, towards the closed position of the control device as the flow velocity increases.   
 
         [0044]    Fluids with different viscosities will provide different forces in each zone depending on the design of these zones, in order to optimize the efficiency and flow through properties of the control device, the design of the areas will be different for different applications, e.g. constant volume flow, or gas/oil or oil/water flow. Hence, for each application the areas needs to be carefully balanced and optimally designed taking into account the properties and physical conditions (viscosity, temperature, pressure etc.) for each design situation. 
         [0045]      FIG. 2B  shows a cross-section through a valve arrangement  12   a  as described in PCT//EP2011/050471. The device consists of first disc-shaped housing body  31  with a central hole or inlet port  13   b  and a second disc-shaped holder body  34 , as well as a preferably flat disc or freely movable valve body  36  provided in an open recess or chamber  37  formed between the first disc-shaped housing  31  and second holder body  34 . The valve body  36  may for particular applications and adjustments depart from the flat shape and have a partly conical or semicircular surface facing the inlet port  13   b.  A flow path through the valve arrangement is shown by the arrows A, where the fluid enters the control device through the central hole or inlet port  13   b  and flows towards and radially over the outer periphery of the disc  26  before flowing through radial openings  39  formed in the second holder body  34 . The entire valve assembly is removably mounted in an opening through a production pipe by means of a threaded connection indicated in  FIG. 2B . 
         [0046]    In operation, the inlet port  13   b  is connected to the recess by a central aperture or opening, wherein the fluid is arranged to flow into the recess  37  through the central aperture from the formation. The fluid is then arranged to flow out of the recess radially across a first surface  26   a  of the valve body, said first surface facing the central aperture, and past the outer peripheral surface of said valve body towards at least one outlet port  39 , which can be radially ( FIG. 2B ) or axially oriented in the valve arrangement. 
         [0047]    The valve arrangement in  FIG. 2B  exploits the Bernoulli effect, in the same way as the valve in  FIG. 2A , teaching that the sum of static pressure, dynamic pressure and friction is constant along a flow line. The main difference between these valves is that the calculations for determining the pressure difference across the disc does not include the area A3 ( FIG. 2A ), as the outlet is located outside the periphery of the disc. Also, the valve arrangement shown in  FIG. 2B  does not use the static pressure on the area A4, below the disc, as the fluid leaves the chamber  37  radially outside the disc  26 . 
         [0048]      FIGS. 2A and 2B  illustrate the normal function of an autonomous valve of this type. The operation of such a valve arrangement provided with a heat expandable means according to the invention is described in connection with  FIGS. 3A and 3B . 
         [0049]      FIG. 3A  shows a valve arrangement as shown in  FIG. 2A  provided with a heat expandable means according to a first embodiment of the invention. For corresponding parts of the valve, the same reference numbers are used. According to this example, an expandable means in the form of a bellows  20  is arranged in a fluid chamber  27  in the valve, which chamber contains a movable valve body in the form of a disc  26  controlling the fluid flow through the valve. The position of the disc  26  is normally controlled by an inflow of fluid from an inlet port  13   a  located facing the centre of the disc  26  and flowing radially outwards over at least a portion of the disc  26  and towards an outlet port  29 . In this example, the bellows  20  is located on the opposite side of the disc  26  relative to the fluid inlet port  13   a.  The bellows  20  comprises a first and a second substantially flat end surface  20   a  and  20   b,  which are connected by a corrugated section  20   c.  The sealed, expandable bellows  20  is at least partially filled with a fluid material that is arranged to undergo a phase change at a predetermined temperature. In this case the first end surface  20   a  of the bellows  20  is attached to a wall section of the fluid chamber  27  and is expandable into contact with the disc  26 . Alternatively, the expandable means can be attached to the disc and expandable into contact with a wall section of the fluid chamber. 
         [0050]    When an undesirable increase of temperature in the fluid flowing through the valve occurs, heat is transferred by the hot fluid to the bellows  20 , partially through the disc  26  and partially around the outer edges thereof to the space between the chamber  27  and the disc  26  where the expandable means is located. If the expandable means contains a liquid, said liquid will begin to boil when the fluid flowing through the valve exceeds a predetermined temperature. This causes the bellows  20  to expand due to the increase in pressure and volume inside said bellows  20 . As the bellows  20  expands it will displace the disc  26  towards its closed position and, if the temperature increase is sufficient, eventually close the valve. 
         [0051]    The method of attachment of the bellows to a wall section as described here can also be used for the embodiment shown in  FIG. 3B  below. 
         [0052]      FIG. 3B  shows a valve arrangement as shown in  FIG. 2B  provided with a heat expandable means according to a second embodiment of the invention. For corresponding parts of the valve, the same reference numbers are used. According to this example, an expandable means in the form of a bellows  30  is arranged in a fluid chamber  37  in the valve, which chamber contains a movable valve body in the form of a disc  36  controlling the fluid flow through the valve. The position of the disc  36  is normally controlled by an inflow of fluid from an inlet port  13   a  located facing the centre of the disc  36  and flowing radially outwards over at least a portion of the disc  36  and towards an outlet port  39 . In this example, the bellows  30  is located on the opposite side of the disc  36  relative to the fluid inlet port  13   a.  The bellows  30  comprises a first and a second substantially flat end surface  30   a  and  30   b,  which are connected by a corrugated section  30   c.  The sealed, expandable bellows  30  is at least partially filled with a fluid material that is arranged to undergo a phase change at a predetermined temperature. In this case the first end surface  30   a  of the bellows  30  is attached to the disc  36  and is expandable into contact with a wall section of the fluid chamber  37 . Alternatively, the expandable means can be attached to the disc and expandable into contact with a wall section of the fluid chamber. 
         [0053]    When an undesirable increase of temperature in the fluid flowing through the valve occurs, heat is transferred by the hot fluid to the bellows  30 , partially through the disc  36  and partially around the outer edges thereof to the space between the chamber  37  and the disc  36  where the expandable means is located. If the expandable means contains a liquid, said liquid will begin to boil when the fluid flowing through the valve exceeds a predetermined temperature. This causes the bellows  30  to expand due to the increase in pressure and volume inside said bellows  30 . As the bellows  30  expands it will displace the disc  36  towards its closed position and, if the temperature increase is sufficient, eventually close the valve. 
         [0054]    The method of attachment of the bellows to the disc as described here can also be used for the embodiment shown in  FIG. 3A  above. 
         [0055]    The expandable means described in connection with  FIGS. 3A and 3B  is a sealed container in the form of a bellows, at least partially filled with a fluid material. Alternatively, the container can have a predetermined general shape with at least a portion being resiliently deformable, or be in the form of a bag with a non-specified shape. In this case, the expandable means can be held in a desired position by locating means on the movable valve body or the chamber wall, without being physically attached to either component. For example, the expandable means can be maintained in position by locating means in the form of a number of projections extending into the chamber to support the movable valve body in its end position where the valve is fully open. Examples of such supporting projections can be found in the filed international application PCT//EP2011/050471. This alternative is preferable for expandable means having a substantially shapeless form, which can expand uniformly in all directions. 
         [0056]      FIG. 4  shows a valve arrangement provided with a heat expandable means according to a third embodiment of the invention. The valve arrangement is arranged to be mounted in a production line (not shown). According to this embodiment, a heat expandable means in the form of a bellows  40  is arranged in a fluid conduit  41 ,  42 ,  43  in series with the fluid flow through the valve arrangement. In this example, the bellows  40  is located in a housing  44  supplied by a first conduit  41  through which the entire fluid flow from the formation passes, before passing to a valve  45  to be controlled through a second conduit  42 . The fluid flow leaves the valve  45  through a third conduit  43  and enters the production pipe. The bellows  40  is connected to a movable valve body  46  (schematically indicated) in order to act on said valve body to close the valve  45 . When an increase of temperature in the fluid flowing through the housing  44  and the valve  45  occurs, heat is transferred by the hot fluid to a liquid inside the bellows  40 . When the fluid flowing through the valve exceeds a predetermined temperature, the liquid in the bellows  40  will begin to boil. This causes the bellows  40  to expand due to the increase in pressure and volume inside said bellows  40 . As the bellows  40  expands it will urge the movable valve body  46  towards its closed position and, if the temperature increase is sufficient, eventually close the valve  45 . 
         [0057]      FIG. 5  shows a valve arrangement provided with a heat expandable means according to a fourth embodiment of the invention. The valve arrangement is arranged to be mounted in a production line (not shown). According to this embodiment, a heat expandable means in the form of a bellows  50  is arranged in a fluid conduit  51  in parallel with a main conduit  52 ,  53  supplying fluid flow through a valve  55 . In this example, the bellows  50  is located in a housing  54  supplied by a first conduit  51  through which a part of the fluid flow from the formation passes, which partial flow bypasses the valve  55  to be controlled. A second conduit  52  supplies the main fluid flow to the valve  55 . The main fluid flow leaves the valve  55  through a third conduit  53 , which is rejoined by the first conduit  51  before entering the production pipe. The bellows  50  is connected to a movable valve body  56  (schematically indicated) in order to act on said valve body to close the valve  55 . When an increase of temperature in the fluid flowing through the housing  54  and the valve  55  occurs, heat is transferred by the hot fluid to a liquid inside the bellows  50 . When the fluid flowing through the housing  54  exceeds a predetermined temperature, the liquid in the bellows  50  will begin to boil. This causes the bellows  50  to expand due to the increase in pressure and volume inside said bellows  50 . As the bellows  50  expands it will urge the movable valve body  56  towards its closed position and, if the temperature increase is sufficient, eventually close the valve  55 .