Patent Description:
Annular barriers are used downhole to provide isolation of one zone from another in an annulus in a borehole of a well between a well tubular metal structure and the borehole wall or another well tubular metal structure. When expanding annular barriers, it is important that the annular barriers are expanded to abut the inner face of the borehole or other well tubular metal structure to provide proper zonal isolation. An example of an annular barrier is known from <CIT>.

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved downhole completion system ensuring that all annular barriers are expanded to abut the inner face of the borehole or other well tubular metal structure to provide proper zonal isolation.

The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a downhole completion system for isolating several zones in a well having a top, comprising:.

Additionally, the above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a downhole completion system for isolating several zones in a well having a top, comprising:.

In addition, the second annular barrier may expand prior to expansion of the first and third annular barriers in that:.

Furthermore, the second pressure may be equal to or the same as the third pressure.

When expanding three or more annular barriers simultaneously against an inner face of an impermeable part of the borehole formation or against another well tubular metal structure, there is a risk that the middle annular barrier cannot be fully expanded. If the well tubular metal structure comprises three annular barriers, and there is a risk that the second middle annular barrier between the first annular barrier and the third annular barrier will be unable to fully expand if the expandable metal sleeve of the first and third annular barriers abut the inner face first, then the first and third annular barriers will enclose a volume of liquid, and the expandable metal sleeve of the second middle annular barrier will not be able to fully expand since the liquid in the volume cannot be displaced through the impermeable formation or the other well tubular metal structure. By having the second annular barrier arranged in between the first annular barrier and the third annular barrier and by it being configured to expand at a lower pressure than the first and third annular barriers, it is ensured that all three annular barriers are able to fully expand. This is of special importance if the first and second annular barriers isolate a production zone, and the second and third annular barriers isolate a water-producing zone. Also when the three annular barriers are to carry a certain load when used for hanging off a liner, it is important that all the annular barriers are carrying the intended load, and in such situation, the expandable metal sleeves of the annular barriers are expanded to abut the inner face of another well tubular metal structure.

Moreover, the expandable metal sleeve of the second annular barrier may expand at a lower pressure than the expandable metal sleeve of the first and third annular barriers.

Furthermore, the expandable metal sleeve of the second annular barrier may have a first thickness being smaller than a second thickness of the expandable metal sleeve of the first and third annular barriers.

In addition, the expandable metal sleeve of the second annular barrier may be made of a metal material being more ductile than the metal material of the expandable metal sleeve of the first and third annular barriers.

Also, the expandable metal sleeve of the second annular barrier may be more flexible than the expandable metal sleeve of the first and third annular barriers.

Further, the expandable metal sleeve of the second annular barrier may be made of a metal material being more flexible than the metal material of the expandable metal sleeve of the first and third annular barriers.

Moreover, the second annular barrier may comprise means for expanding the second annular barrier before the first and third annular barriers.

Furthermore, the means may be that the expandable metal sleeve of the second annular barrier has a first thickness being smaller than a second thickness of the expandable metal sleeve of the first and third annular barriers.

In addition, the means may be that the expandable metal sleeve of the second annular barrier is made of a metal material being more ductile than the metal material of the expandable metal sleeve of the first and third annular barriers.

Also, the means may be that the expandable metal sleeve of the second annular barrier is made of a metal material being more flexible than the metal material of the expandable metal sleeve of the first and third annular barriers.

Further, the downhole completion system may comprise a fourth annular barrier arranged next to the first annular barrier closer to the top and a fifth annular barrier next to the third annular barrier furthest away from the top, the second thickness of the expandable metal sleeve of the first and third annular barriers being smaller than a third thickness of the expandable metal sleeve of the fourth and fifth annular barriers.

Moreover, the expandable metal sleeve of the first and third annular barriers may have several sections having a greater thickness than other sections of the expandable metal sleeve of the first and third annular barriers, and the expandable metal sleeve of the second annular barrier may have fewer sections having a greater thickness than other sections of the expandable metal sleeve of the second annular barrier.

Furthermore, the expandable metal sleeve of the first and third annular barriers may have several sections having a greater thickness than other sections of the expandable metal sleeve of the first and third annular barriers, and the expandable metal sleeve of the second annular barrier may not have any sections having a greater thickness than other sections of the expandable metal sleeve of the second annular barrier.

In addition, the first and third annular barriers may be provided with a dissolvable disc in the fluid channel between the expansion opening and the annular barrier space.

Also, the first and third annular barriers may be provided with a dissolvable disc in the fluid channel between the expansion opening and the annular barrier space, and the second annular barrier may have no dissolvable disc in the fluid channel between the expansion opening and the annular barrier space.

Further, the dissolvable disc may be designed so that the second annular barrier is fully expanded before the first and third annular barriers initiate expansion.

Moreover, the first and third annular barriers may be provided with a shear disc in the fluid channel between the expansion opening and the annular barrier space.

Furthermore, the second annular barrier may be fully expanded at a predetermined pressure, and the shear disc is sheared at a differential pressure matching the predetermined pressure so that the second annular barrier is fully expanded before the first and third annular barriers initiate expansion.

In addition, the first and third annular barriers may be provided with a shear disc in the fluid channel between the expansion opening and the annular barrier space, the second annular barrier having no shear disc in the fluid channel between the expansion opening and the annular barrier space.

Furthermore, the second annular barrier may be provided with a shear disc in the fluid channel between the expansion opening and the annular barrier space, the shear disc of the second annular barrier being designed to break at a lower pressure than that of the shear disc of the first and third annular barriers.

Also, the first and third annular barriers may be provided with a shear pin valve having a piston in a bore maintained in a first position by a shear pin which breaks at a predetermined pressure, shifting the piston to a second position in which fluid is allowed to flow from the expansion opening to the annular barrier space.

Moreover, the second annular barrier may comprise a pressure intensifier configured to increase the pressure entering the expansion opening before entering the annular barrier space.

Furthermore, the first and third annular barriers may have no pressure intensifier or a pressure intensifier which increases the pressure less than the pressure intensifier of the second annular barrier.

In addition, the second annular barrier may comprise a first pressure intensifier configured to increase the pressure entering the expansion opening before entering the annular barrier space, and the second annular barrier may comprise a second pressure intensifier configured to increase the pressure entering the expansion opening of the second annular barrier before entering the annular barrier space of the second annular barrier by <NUM>-<NUM> bars more than the first pressure intensifier.

Moreover, the first and third annular barriers may comprise a first pressure intensifier configured to increase the pressure entering the expansion opening before entering the annular barrier space, and the second annular barrier may comprise a second pressure intensifier configured to increase the pressure entering the expansion opening of the second annular barrier before entering the annular barrier space of the second annular barrier by <NUM>-<NUM> bars more than the first pressure intensifier.

Also, the first and third annular barriers may comprise a pressure relief valve in the fluid channel.

Further, the first and third annular barriers may comprise a sequence valve which is activated to open for fluid communication to the annular barrier spaces of the first and third annular barriers at a predetermined pressure in the annular barrier space of the second annular barrier.

Moreover, the first and third annular barriers may each comprise a throttle valve in the fluid channel.

Furthermore, the first and third annular barriers may each comprise a throttle valve in the fluid channel, and the second annular barrier may have no throttle valve in the fluid channel.

In addition, the first and third annular barriers may each comprise an activation unit for bringing a valve from a closed position to an open position when the pressure in the annular barrier space of the second annular barrier is above a predetermined pressure.

Also, the first and third annular barriers may each comprise an activation unit for bringing a valve from a closed position to an open position, the activation unit being activated by a pressure increase in the annular barrier space of the second annular barrier.

Further, each end section of the expandable metal sleeve of the second annular barrier may be connected to the tubular metal part by means of a connection part, each connection part being slidably connected to the tubular metal part.

Moreover, the first and third annular barriers may each comprise an orifice in the fluid channel, the fluid channel being fluidly connected to the annular barrier space upstream of the orifice so that a pressure increase upstream of the orifice activates a valve opening for fluid communication to the annular barrier space when the pressure increase is above a certain level.

Furthermore, the first and third annular barriers may each comprise an orifice in the fluid channel, the fluid channel being fluidly connected to the annular barrier space upstream of the orifice, the inner diameter of the fluid channel of the second annular barrier being larger than the inner diameter of the orifice.

In addition, when the inner diameter of the fluid channel of the second annular barrier is larger than the inner diameter of the orifice, the second annular barrier may be expanded at a lower flow rate than the first and third annular barriers.

Also, the well tubular metal structure may be connected with the drill pipe or coiled tubing closer to the top of the well than the first annular barrier.

Further, the well tubular metal structure may have a first end closest to the top and a second end, the downhole completion system further comprising a drill pipe or coiled tubing connected at a first end with the well tubular metal structure at the first end of the well tubular metal structure.

Moreover, the annular barrier space of the second annular barrier may comprise a compound such as a swellable material increasing the expansion rate of the second annular barrier compared to that of the first and third annular barriers.

The invention also relates to a downhole completion method for completing a downhole completion system according to any of the preceding claims, comprising:.

Moreover, during the pressurising of the well tubular metal structure to a first pressure and expansion of the second annular barrier, the first and third annular barriers may remain unexpanded.

Furthermore, the expansion of the first and third annular barriers may be initiated after the expansion of the second annular barrier has been initiated.

In addition, the completion method may comprise increasing the pressure to a second pressure to also expand the first and third annular barriers.

Further, before lowering the well tubular metal structure, the downhole completion method may comprise connecting a drill pipe to a first end of the well tubular metal structure, and lowering the well tubular metal structure may also comprise lowering the drill pipe into the borehole until the well tubular metal structure is arranged in a predetermined position, the pressurising of the well tubular metal structure also comprising pressurising the drill pipe.

Finally, the pressurising of the well tubular metal structure to a first pressure may be performed at a predetermined first flow rate, the downhole completion method further comprising increasing the flow rate to a second flow rate to also expand the first and third annular barriers.

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which:.

<FIG> shows a downhole completion system <NUM> having three unexpanded annular barriers <NUM> mounted as part of a well tubular metal structure <NUM> arranged in a borehole <NUM> in a well <NUM>. In <FIG>, the middle second annular barrier <NUM>, 1b has been expanded before the outermost first and third annular barriers <NUM>, 1a, 1c. An expandable metal sleeve <NUM> of the second annular barrier has been expanded to abut an inner face <NUM> of the borehole, and in this way, it is ensured that the middle annular barrier is expanded.

When expanding three or more annular barriers <NUM> simultaneously against an inner face of an impermeable part of the borehole formation or against another well tubular metal structure, there is a risk that the middle annular barrier cannot be fully expanded. If the well tubular metal structure comprises three annular barriers, and there is a risk that the second middle annular barrier between the first annular barrier and the third annular barrier will be unable to fully expand if the expandable metal sleeve of the first and third annular barriers abut the inner face first, the first and third annular barriers will enclose a volume of liquid, and the expandable metal sleeve of the second middle annular barrier then cannot fully expand since the liquid in the volume cannot be displaced through the impermeable formation or the other well tubular metal structure.

In <FIG>, the downhole completion system <NUM> for isolating several zones <NUM>, <NUM>, <NUM>, <NUM> in a well <NUM> comprises the well tubular metal structure <NUM> and a first annular barrier <NUM>, 1a, a second annular barrier <NUM>, 1b and a third annular barrier <NUM>, 1c. Each annular barrier comprises a tubular metal part <NUM> mounted as part of the first well tubular metal structure <NUM>, an expandable metal sleeve <NUM> surrounding the tubular metal part <NUM>, and each end section <NUM>, <NUM> of the expandable metal sleeve <NUM> being connected with the tubular metal part <NUM>. Each annular barrier <NUM> further comprises an annular barrier space <NUM> between the tubular metal part <NUM> and the expandable metal sleeve <NUM>, and an expansion opening <NUM> is provided in the tubular metal part <NUM>, and a fluid channel <NUM> is fluidly connecting the expansion opening <NUM> and the annular barrier space <NUM>, through which opening <NUM> and fluid channel <NUM> pressurised fluid passes for expanding the expandable metal sleeve <NUM> and bringing the annular barrier <NUM> from an unexpanded position to an expanded position. The second annular barrier 1b is arranged in between the first annular barrier and the third annular barrier 1a, 1c, and the second annular barrier 1b is configured to expand at a lower pressure than the first and third annular barriers 1a, 1c, so that the second annular barrier 1b is expanded before the first and third annular barriers 1a, 1c, as shown in <FIG>. In <FIG>, the first and third annular barriers 1a, 1c have also been expanded. Thus, the expandable metal sleeve <NUM> of the second annular barrier 1b expands at a lower pressure or at a lower flow rate in the well tubular metal structure <NUM> than the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c.

Thus in <FIG>, the second annular barrier expands at a first pressure, the first annular barrier expands at a second pressure, and the third annular barrier expands at a third pressure or the second pressure, where the first pressure is lower than the second and third pressure. The second pressure is substantially the same as or equal to the third pressure.

In <FIG>, the second annular barrier 1b is configured to expand at a lower pressure than the first and third annular barriers 1a, 1c in that the unexpanded expandable metal sleeve <NUM> of the second annular barrier 1b has a first thickness t<NUM> being smaller than a second thickness t<NUM> of the expandable metal sleeve <NUM> of the third annular barrier 1c. Even though not shown, the first annular barrier 1a may have the same thickness as the third annular barrier 1c. In the event that the downhole completion system <NUM> comprises more than three annular barriers, the outermost annular barriers may have a higher thickness than that of the first and third annular barriers 1a, 1c in order to ensure that the first and third annular barriers 1a, 1c expand and that their expandable metal sleeves <NUM> abut the inner face <NUM> before the expandable metal sleeves <NUM> of the outermost annular barriers.

In another aspect, the second annular barrier 1b is configured to expand at a lower pressure than the first and third annular barriers 1a, 1c in that the expandable metal sleeve <NUM> of the second annular barrier 1b is made of a metal material being more ductile than that of the metal material of the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c.

In another aspect, the second annular barrier 1b is configured to expand at a lower pressure than the first and third annular barriers 1a, 1c in that the expandable metal sleeve <NUM> of the second annular barrier 1b is more flexible than the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c.

Thus, the expandable metal sleeve <NUM> of the second annular barrier 1b may be made of a metal material being more flexible than that of the metal material of the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c so that the second annular barrier is configured to expand at a lower pressure than the first and third annular barriers.

In the downhole completion system <NUM>, the second annular barrier 1b thus comprises means for expanding the second annular barrier 1b before the first and third annular barriers 1a, 1c. The means may be one of several means where one is that the expandable metal sleeve <NUM> of the second annular barrier 1b has a first thickness t<NUM> being smaller than a second thickness t<NUM> of the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c. Another means may be that the expandable metal sleeve <NUM> of the second annular barrier 1b is made of a metal material being more ductile than the metal material of the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c. Yet another means may be that the expandable metal sleeve <NUM> of the second annular barrier 1b is made of a metal material being more flexible than the metal material of the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c.

As shown in <FIG>, in order for the second annular barrier 1b to expand at a lower pressure than the first and third annular barriers 1a, 1c, the second annular barrier 1b comprises a pressure intensifier <NUM> configured to increase the pressure entering the expansion opening <NUM> before entering the annular barrier space <NUM>. The first and third annular barriers 1a, 1c have no pressure intensifier <NUM> or a pressure intensifier which increases the pressure less than the pressure intensifier <NUM> of the second annular barrier 1b. Thus, the first and third annular barriers 1a, 1c may comprise a first pressure intensifier <NUM> configured to increase the pressure entering the expansion opening <NUM> before entering the annular barrier space <NUM>, and the second annular barrier 1b may comprise a second pressure intensifier <NUM> configured to increase the pressure entering the expansion opening <NUM> of the second annular barrier 1b before entering the annular barrier space <NUM> of the second annular barrier 1b by <NUM>-<NUM> bars more than the first pressure intensifier <NUM>.

The annular barrier of <FIG> comprises the expandable metal sleeve <NUM> surrounding the tubular metal part <NUM>, and each end <NUM>, <NUM> of the expandable metal sleeve <NUM> is connected to the tubular metal part <NUM>, providing the annular barrier space <NUM> between the expandable metal sleeve <NUM> and the tubular metal part <NUM>. The annular barrier further comprises the pressure intensifier <NUM> through which fluid having entered through the expansion opening <NUM> is pressure-intensified before entering the annular barrier space <NUM> to expand the expandable metal sleeve <NUM> at a higher pressure than the pressure of the fluid entering the expansion opening <NUM> in the tubular metal part <NUM>.

In <FIG>, the first and third annular barriers 1a, 1c comprise a pressure relief valve <NUM> in the fluid channel <NUM> in order for the second annular barrier 1b to expand at a lower pressure than the first and third annular barriers 1a, 1c. The pressurised fluid enters the expansion opening <NUM>, continues in the fluid channel <NUM> and into the pressure relief valve <NUM> before continuing in the fluid channel <NUM> through the connection part <NUM> and then entering the annular barrier space <NUM> underneath the expandable metal sleeve <NUM> to expand the expandable metal sleeve <NUM>.

In order for the second annular barrier 1b to expand at a lower pressure than the first and third annular barriers 1a, 1c, the first and third annular barriers 1a, 1c may be provided with a shear disc <NUM> in the fluid channel <NUM> between the expansion opening <NUM> and the annular barrier space <NUM>, as shown in <FIG>. The second annular barrier 1b is fully expanded at a predetermined pressure, and the shear disc <NUM> of the first and third annular barriers 1a, 1c is sheared at a differential pressure matching the predetermined pressure so that the second annular barrier 1b is fully expanded before the first and third annular barriers 1a, 1c initiate expansion. The first and third annular barriers 1a, 1c are provided with a shear disc <NUM> in the fluid channel <NUM> between the expansion opening <NUM> and the annular barrier space <NUM>, and the second annular barrier 1b has no shear disc in the fluid channel <NUM> between the expansion opening <NUM> and the annular barrier space <NUM>. The second annular barrier 1b may also have a shear disc in the fluid channel <NUM>, but this shear disc <NUM> is sheared at a lower pressure than that of the shear disc <NUM> in the first and third annular barriers 1a, 1c.

Instead of a shear disc, the first and third annular barriers 1a, 1c may be provided with a dissolvable disc (not shown) in the fluid channel <NUM> between the expansion opening <NUM> and the annular barrier space <NUM>. The first and third annular barriers 1a, 1c are provided with the dissolvable disc (not shown) in the fluid channel <NUM> between the expansion opening <NUM> and the annular barrier space <NUM>, and the second annular barrier 1b has no dissolvable disc in the fluid channel <NUM> between the expansion opening <NUM> and the annular barrier space <NUM>. The dissolvable disc is designed so that the second annular barrier 1b is fully expanded before it is dissolved and the first and third annular barriers initiate expansion.

In another aspect, the first and third annular barriers 1a, 1c comprise a sequence valve <NUM>, as shown in <FIG>, which is activated to open for fluid communication to the annular barrier spaces <NUM> of the first and third annular barriers 1a, 1c at a predetermined pressure in the annular barrier space <NUM> of the second annular barrier 1b. Each sequence valve <NUM> of the first and third annular barriers 1a, 1c may thus be fluidly connected by means of a flow tube to the annular barrier space <NUM> of the second annular barrier 1b in order to activate the sequence valves <NUM> and open for expansion of the first and third annular barriers 1a, 1c.

<FIG> shows the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c and has several sections 10a having a greater thickness than other sections 10b of the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c. The expandable metal sleeve <NUM> of the second annular barrier 1b may have no sections having a greater thickness than other sections 10b of the expandable metal sleeve <NUM>, or the expandable metal sleeve <NUM> of the second annular barrier 1b may have fewer sections having a greater thickness than other sections of the expandable metal sleeve <NUM> of the second annular barrier 1b. The expandable metal sleeve <NUM> of <FIG> has several sections 10a having a greater thickness than other sections 10b, and the sections 10a having the greater thickness also have an uneven thickness.

In <FIG>, an annular barrier <NUM> mounted as part of the well tubular metal structure <NUM> with a longitudinal axis <NUM> is shown in a cross-sectional view where the expandable metal sleeve <NUM> of the annular barrier has an uneven thickness as the expandable metal sleeve <NUM> has several sections 10a having a greater thickness than other sections 10b of the expandable metal sleeve <NUM>. At the sections 10a having a greater thickness than other sections, the expandable metal sleeve <NUM> has projections in between split ring-shaped retaining elements <NUM>, each having three windings extending around the expandable metal sleeve <NUM>, and the sealing element <NUM> also extending around the expandable metal sleeve <NUM>.

In yet another aspect, the first and third annular barriers 1a, 1c are provided with a shear pin valve <NUM>, as shown in <FIG>, having a piston <NUM> in a bore <NUM> maintained in a first position by a shear pin <NUM> which breaks at a predetermined pressure, shifting the piston <NUM> to a second position in which fluid is allowed to flow from the expansion opening <NUM> via the fluid channel <NUM> to the annular barrier space <NUM>. The piston <NUM> has seals <NUM> in order to seal to the inner face <NUM> of the bore <NUM>. When a predetermined pressure is reached, being above the second pressure required to expand the second annular barrier 1b, the shear pin <NUM> breaks and the piston <NUM> of the shear pin valve <NUM> changes position so that the fluid can enter the annular barrier space <NUM> and expand the expandable metal sleeve <NUM>. The shear pin valve has a venting port <NUM>.

In order for the second annular barrier 1b to expand at a lower pressure than the first and third annular barriers 1a, 1c, the first and third annular barriers 1a, 1c may in another aspect each comprise a throttle valve in the fluid channel <NUM>. The first and third annular barriers 1a, 1c each comprise a throttle valve in the fluid channel <NUM>, and the second annular barrier 1b has no throttle valve in the fluid channel <NUM>. In this way, the second annular barrier 1b is expanded before the first and third annular barriers 1a, 1c.

In yet another aspect, the first and third annular barriers 1a, 1c each comprise an activation unit for bringing a valve from a closed position to an open position when the pressure in the annular barrier space <NUM> of the second annular barrier 1b is above a predetermined pressure. The activation unit may be activated by a pressure increase in the annular barrier space <NUM> of the second annular barrier 1b. This may be measured by a sensor communicating with the activation unit through an electric wire or wirelessly.

Even though not shown, each end section <NUM>, <NUM> of the expandable metal sleeve <NUM> of the second annular barrier 1b may be connected to the tubular metal part <NUM> by means of a connection part <NUM>, where each connection part is slidably connected to the tubular metal part <NUM> so that the expandable metal sleeve <NUM> of the second annular barrier 1b is more easily expanded radially outwards than the expandable metal sleeve <NUM> of the first and third annular barriers 1a, 1c having expandable metal sleeves <NUM> that are fixedly fastened to the tubular metal part <NUM>, either by welding, bite fitting or a crimped connection.

In order for the second annular barrier 1b to expand at a lower flow rate instead of at a lower pressure than the first and third annular barriers 1a, 1c, the first and third annular barriers 1a, 1c may in another aspect each comprise an orifice in the fluid channel <NUM>. The fluid channel <NUM> is fluidly connected to the annular barrier space <NUM> upstream of the orifice so that a pressure-increase upstream of the orifice due to a high flow of fluid activates a valve which opens for fluid communication to the annular barrier space <NUM> when the pressure increase is above a certain level. The inner diameter of the fluid channel <NUM> of the second annular barrier 1b is larger than the inner diameter of the orifice of the first and third annular barriers 1a, 1c. When the inner diameter of the fluid channel <NUM> of the second annular barrier 1b is larger than the inner diameter of the orifice, the second annular barrier 1b is expanded at a lower flow rate than the first and third annular barriers 1a, 1c. In this way, the second annular barrier 1b can be expanded at one flow rate before the flow rate is increased, and the first and third annular barriers 1a, 1c are then expanded. In order to be able to vary the flow rate of the pressurised fluid, the well tubular metal structure <NUM> is connected with the drill pipe or coiled tubing closer to the top of the well than the first annular barrier 1a so that the flow rate can be changed, e.g., from one barrel per minute for expanding the second annular barrier 1b to two barrels per minute for expanding the first and third annular barriers 1a, 1c. The well tubular metal structure <NUM> has a first end closest to the top of the well and a second end. The downhole completion system further comprises a drill pipe or coiled tubing connected at a first end with the well tubular metal structure <NUM> at the first end of the well tubular metal structure <NUM>.

The downhole completion method for completing a downhole completion system <NUM> as described above comprises mounting tubular sections with tubular metal parts <NUM> of the well tubular metal structure <NUM> having the first, second and third annular barriers 1a, 1b, 1c, and the second annular barrier 1b being mounted to be arranged in between the first annular barrier and the third annular barrier 1a, 1c. The downhole completion method further comprises lowering the well tubular metal structure <NUM> in the well until the well tubular metal structure <NUM> is arranged in a predetermined position and pressurising the well tubular metal structure <NUM> to a first pressure and expanding the second annular barrier 1b. During the pressurising of the well tubular metal structure <NUM> from within to a first pressure and expansion of the second annular barrier 1b, the first and third annular barriers 1a, 1c remain unexpanded. The expansion of the first and third annular barriers 1a, 1c is initiated after the expansion of the second annular barrier 1b has been initiated, and for some aspects described above, the expansion of the first and third annular barriers 1a, 1c is initiated after the expansion of the second annular barrier 1b has ended.

The downhole completion method further comprises increasing the pressure to a second pressure to expand also the first and/or third annular barriers 1a, 1c or increasing the flow rate to a second flow rate to expand also the first and third annular barriers 1a, 1c.

The downhole completion method further comprises increasing the pressure to a third pressure to also expand the other of the first and third annular barriers 1a, 1c.

The downhole completion method where the flow rate has to be increased in order for the second annular barrier 1b to expand before the first and third annular barriers 1a, 1c comprises connecting a drill pipe to a first end of the well tubular metal structure <NUM> before lowering the well tubular metal structure <NUM>, and then lowering the well tubular metal structure <NUM> also comprises lowering the drill pipe into the borehole <NUM> until the well tubular metal structure <NUM> is arranged in a predetermined position, the pressurising of the well tubular metal structure <NUM> also comprising pressurising the drill pipe. Then, the pressurising of the well tubular metal structure <NUM> to a first pressure is performed at a predetermined first flow rate, the downhole completion method further comprising increasing the flow rate to a second flow rate to expand also the first and third annular barriers 1a, 1c.

By "fluid" or "well fluid" is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By "gas" is meant any kind of gas composition present in a well, completion or open hole, and by "oil" is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil and water fluids may thus all comprise other elements or substances than gas, oil and/or water, respectively.

By "casing" or "well tubular metal structure" is meant any kind of pipe, tubing, tubular, liner, string, etc., used downhole in relation to oil or natural gas production.

In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.

Claim 1:
Downhole completion system (<NUM>) for isolating several zones (<NUM>, <NUM>, <NUM>, <NUM>) in a well (<NUM>) having a top, comprising:
- a well tubular metal structure (<NUM>) arranged in a borehole (<NUM>) having an inner face (<NUM>) in the well, and
- a first annular barrier (<NUM>, 1a), a second annular barrier (<NUM>, 1b) and a third annular barrier (<NUM>, 1c), each annular barrier comprising:
- a tubular metal part (<NUM>), the tubular metal part being mounted as part of the well tubular metal structure,
- an expandable metal sleeve (<NUM>) surrounding the tubular metal part, each end section (<NUM>, <NUM>) of the expandable metal sleeve being connected with the tubular metal part,
- an annular barrier space (<NUM>) between the tubular metal part and the expandable metal sleeve, and
- an expansion opening (<NUM>) in the tubular metal part and a fluid channel (<NUM>) fluidly connecting the expansion opening and the annular barrier space through which pressurised fluid passes for expanding the expandable metal sleeve and bringing the annular barrier from an unexpanded position to an expanded position, wherein the second annular barrier is arranged in between the first annular barrier and the third annular barrier, and the second annular barrier expands at a first pressure, the first annular barrier expands at a second pressure, the third annular barrier expands at a third pressure, and the first pressure is lower than the second pressure and/or third pressure.