AU2012356949A1

AU2012356949A1 - Production system for producing hydrocarbons from a well

Info

Publication number: AU2012356949A1
Application number: AU2012356949A
Authority: AU
Inventors: Jorgen Hallundbaek
Original assignee: Welltec AS
Current assignee: Welltec AS
Priority date: 2011-12-23
Filing date: 2012-12-21
Publication date: 2014-07-24
Anticipated expiration: 2032-12-21
Also published as: WO2013092945A1; DK2795052T3; MX2014006957A; MX342054B; US20140352956A1; BR112014013982A2; RU2014127616A; CN104254664A; EP2795052A1; EP2607616A1; EP2795052B1; CA2858643A1; AU2012356949B2

Abstract

The present invention relates to a production system (1) for producing hydrocarbons from a well (2). Said production system comprises a production casing (3), a monitoring unit adapted to measure a production outcome of the well, a first reservoir zone (6) comprising at least a first fluid (10), extending along and outside part of the production casing, a second reservoir zone (7) comprising at least a second fluid (11), extending along and outside another part of the production casing, a first inflow device arranged in the first reservoir zone having a first inflow area and being adapted to let the first fluid into the production casing at a first volume rate (VI), a second inflow device arranged in the second reservoir zone having a second inflow area and being adapted to let the second fluid into the production casing at a second volume rate (V2), wherein the first and second inflow areas of the inflow devices are adjustable, whereby the first and second inflow devices can be adjusted so that the first volume rate is equal to or higher than the second volume rate. Furthermore, the present invention relates to a well completion comprising the production system according to the invention as well as to a production method for the production of hydrocarbons from a well.

Description

WO 2013/092945 PCT/EP2012/076541 1 PRODUCTION SYSTEM FOR PRODUCING HYDROCARBONS FROM A WELL Field of the invention The present invention relates to a production system for producing hydrocarbons 5 from a well. Furthermore, the present invention relates to a well completion comprising the production system according to the invention as well as to a production method for the production of hydrocarbons from a well. Background art 10 During oil and gas production, it is sometimes necessary to assist the production in a well due to a high hydro-static pressure. If the well itself is not capable of generating the adequate pressure to drive oil or gas to the surface, or the well has been deliberately killed, artificial lift may be used to lift the well fluid at the 15 upper part of the well. By submerging a pump into a well, the pump may be used to boost the pressure or perhaps restart a dead well. The pump sets a plug or seal in the well and pumps well fluid from one side of the plug to the other to overcome the static 20 pressure of the well fluid above the pump. Other methods of artificial lifting use chemicals or gasses to provide the lift required to ensure an acceptable production outcome from the well. However, the known solutions overcoming the static pressure of the well fluid use external 25 energy sources. Summary of the invention It is an object of the present invention to wholly or partly overcome the above 30 disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved production system for producing hydrocarbons from a well without using an artificial lift system, such as a pump, gas or chemicals. The above objects, together with numerous other objects, advantages, and 35 features, which will become evident from the below description, are accomplished WO 2013/092945 PCT/EP2012/076541 2 by a solution in accordance with the present invention by a production system for producing hydrocarbons from a well, comprising - a production casing, - a monitoring unit adapted to measure a production outcome of the well, 5 - a first reservoir zone comprising at least a first fluid, extending along and outside part of the production casing, - a second reservoir zone comprising at least a second fluid, extending along and outside another part of the production casing, - a first inflow device arranged in the first reservoir zone, having a first inflow 10 area and being adapted to let the first fluid into the production casing at a first volume rate, and - a second inflow device arranged in the second reservoir zone, having a second inflow area and being adapted to let the second fluid into the production casing at a second volume rate, 15 wherein the first and second inflow areas of the inflow devices are adjustable, whereby the first and second inflow devices can be adjusted so that the first volume rate is equal to or higher than the second volume rate. Hereby, a production system is obtained wherein the energy in the reservoir and 20 well is used for lifting the well fluid out of the well, substantially without using external energy sources. In an embodiment, the inflow device comprises a first outer sleeve and a second inner sleeve movable in relation to each other, the first outer sleeve having outer 25 inflow openings arranged in rows with a different number of openings in each row, and the second inner sleeve having inner openings, whereby the inflow area of the inflow device is adjustable in that the inner openings of the second inner sleeve can be moved and aligned in relation to the outer openings of the first sleeve. 30 Said inflow openings may be arranged in rows along the inflow device. Furthermore, the inner openings may be arranged with a distance between them in relation to the outer openings, whereby the inflow area of the inflow device is 35 adjustable in that the inner openings of the second inner sleeve can be moved and aligned in relation to the outer openings of the first sleeve.

WO 2013/092945 PCT/EP2012/076541 3 Moreover, the inner openings of the inner sleeve may be arranged with predetermined circumferenctial distances between them so that each row of outer inflow openings can optionally be opened or closed by moving the inner sleeve. 5 In one embodiment, the second inner sleeve may be rotatably movable in relation to the first outer sleeve. In another embodiment, the inflow device may have an axial extension, and the 10 inner sleeve may be slidable in relation to the outer sleeve along the axial extension. Furthermore, the outer sleeve may have a recess in which the inner sleeve slides along the axial extension. 15 In yet another embodiment, the second sleeve may comprise recesses for engaging with a key tool for adjusting the inflow device. In yet another embodiment, the inner sleeve may be slidably movable in relation 20 to the outer sleeve. In addition, the production system as described above may further comprise a monitoring unit adapted to measure a production outcome of the well. 25 Moreover, the monitoring unit may be adapted to measure a water content of the production outcome so that the inflow devices may be adjusted to obtain an optimum between production outcome and water content. Also, the monitoring unit may be adapted to measure a volume rate of the 30 production outcome and/or a pressure at the top of the well so that the inflow devices may be adjusted based on the volume rate and/or pressure measured at the top of the well. In one embodiment, the inflow devices may be manually adjustable. 35 In another embodiment, the inflow devices may be remotely adjustable.

WO 2013/092945 PCT/EP2012/076541 4 Furthermore, the inflow device may be operated by a magnetic source. Moreover, the reservoir zones may be separated by annular barriers. 5 In an embodiment, the system may comprise a plurality of reservoir zones. Further, a plurality of inflow devices may be arranged in the system and/or in each reservoir zone. 10 Said plurality of inflow devices may be arranged in the system and/or in each reservoir zone. Also, the first fluid may be oil and the second fluid may be water or gas. 15 In addition, a valve may be arranged in one or more of the openings. Furthermore, a screen may be arranged outside the openings. In one embodiment, the inflow device may comprise a first packer, the second 20 sleeve may be arranged in a recess of the first sleeve, and the first packer may be arranged between the first sleeve and the second sleeve. Furthermore, the packer may extend around the inner circumferential recess and have an inner diameter which is substantially the same as that of the second 25 sleeve. Moreover, the packer may have a number of through-going packer channels for being aligned with first axial channels in the first sleeve. 30 In addition, the packer may be made of ceramics. In an embodiment, the production casing may comprise annular barriers, each annular barrier being adapted for being expanded in an annulus between the production casing and an inside wall of a borehole downhole, and each annular 35 barrier comprising: - a tubular part for mounting as part of the production casing, WO 2013/092945 PCT/EP2012/076541 5 - an expandable sleeve surrounding the tubular part, each end of the expandable sleeve being fastened to the tubular part by means of a connection part, - an annular barrier space between the tubular part and the expandable sleeve, and 5 - an aperture in the tubular part for letting fluid into the annular barrier space to expand the sleeve, wherein annular barriers are arranged, separating the first reservoir zone and the second reservoir zone. Furthermore, the expandable sleeve may be made of metal. 10 The present invention also relates to a well completion comprising the production system as described above and a well head. The well completion may further comprise a control unit arranged in the well 15 head for adjusting the inflow devices. In addition, the well completion may further comprise a key tool connected with a downhole tractor for adjusting the inflow devices. 20 Further, the present invention relates to a production method for production of hydrocarbons from a well, comprising the steps of: - determining a first reservoir zone comprising at least a first fluid, - determining a second reservoir zone comprising at least a second fluid, - opening a first inflow device in the first zone to let the at least first fluid into a 25 production casing at a first volume rate, - opening a second inflow device in the second zone to let the at least second fluid into the production casing at a second volume rate, - monitoring a production outcome of the well, and - adjusting the first and second inflow devices based on the production outcome 30 so that the first volume rate is equal to or higher than the second volume rate or so that the second volume rate is higher than the first volume rate. In said method, the monitoring step may comprise one or more of the steps of: - measuring a pressure at the top of the well, 35 - measuring a volume rate of the production outcome at the top of the well, and/or - measuring a water content of the production outcome at the top of the well.

WO 2013/092945 PCT/EP2012/076541 6 Also, the step of adjusting the first and second inflow devices may further comprise adjustment of at least one of the inflow devices based on the measured pressure, volume rate and/or water content at the top of the well. 5 Moreover, the step of step of adjusting the first and second inflow devices may be performed manually, e.g. by a key tool connected with a downhole tractor. Additionally, the step of adjusting the first and second inflow devices further may be performed remotely from the top of the well. 10 Finally, the step of adjusting the first and second inflow devices further may be performed wirelessly. Brief description of the drawings 15 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 20 Fig. 1 shows a production system according to one embodiment of the invention, Fig. 2 shows another embodiment of the production system having a plurality of reservoir zones, 25 Fig. 3 shows a diagram of volume rate in relation to pressure, Fig. 4 shows a cross-sectional view of an embodiment of an inflow device, Fig. 5 shows a cross-sectional view of another embodiment of an inflow device, 30 Fig. 6 shows a cross-sectional view of an additional embodiment of an inflow device, Fig. 7 shows, in a partly cross-sectional view and partly in perspective, the inflow 35 device of Fig. 4, WO 2013/092945 PCT/EP2012/076541 7 Figs. 8a-8o show cross-sectional views of different positions of the inflow device of Figs. 4 and 7 in relation to the volume rate, Fig. 9 shows a cross-sectional view of the inflow device of Fig. 6, 5 Fig. 10 shows, in a partly cross-sectional view and partly in perspective, another embodiment of the inflow device having an axially sliding inner sleeve, and Fig. 11 shows a cross-sectional view of the inflow device of Fig. 10 along the axial 10 extension. All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested. 15 Detailed description of the invention Fig. 1 shows a production system 1 for producing hydrocarbons from a well 2. The production system 1 comprises a production casing 3 extending along the 20 well 2. The production system 1 furthermore comprises a monitoring unit 4 adapted to measure a production outcome of the well 2. In this embodiment, the monitoring unit is positioned at the top of the well 2, i.e. at the well head 5. The monitoring unit may comprise a flow measuring device, a pressure sensor, a water cut measuring device or a combination thereof. 25 The production system 1 also comprises a first reservoir zone 6 comprising at least a first fluid 10, extending along and outside the production casing 3, and a second reservoir zone 7 comprising at least a second fluid 11, extending along and outside the production casing. Furthermore, a first inflow device 8 is 30 arranged in the first reservoir zone 6, having a first inflow area and being adapted to let the first fluid 10 into the production casing 3 at a first volume rate V1, and a second inflow device 9 is arranged in the second reservoir zone 7, having a second inflow area and being adapted to let the second fluid 11 into the production casing 3 at a second volume rate V2. The first and second inflow 35 areas of the inflow devices 8, 9 are adjustable, whereby the first and second inflow devices 8, 9 can be adjusted based on the production outcome so that the first volume rate V1 is equal to or higher than the second volume rate V2.

WO 2013/092945 PCT/EP2012/076541 8 Hereby, it is obtained that the production of hydrocarbons from the well 2 may be optimised by adjusting the inflow volume rates of the inflow devices 8, 9 to the instantaneous requirement based on either the volume rate of the production outcome, the pressure at the top of the well 2, the water content of the 5 production outcome, or a combination thereof. Thus, by means of the present system, it is possible to create lift of the fluids in the well by adjusting the inflow volume rates of the fluids and thereby avoid using artificial lift or at least substantially reduce the use of artificial lift. 10 In the event that the first fluid 10 comprises more water or gas, it may be used for driving the second and heavier fluid 11, and thus, artificial lift higher up the well may be avoided. Similarly, the second fluid may have a higher content of water which is normally shut off by hindering its inflow into the casing, however, the second fluid may be useful for mixing with the first fluid to ease the flow of 15 the well of the first fluid. In the production system 1 shown in Fig. 1, the first and second reservoir zones 6, 7 are adjacent zones, and they are separated from each other by expandable annular barriers 12. In Fig. 1, the first fluid 10 in the first reservoir zone 6 is 20 essentially oil and the second fluid 11 in the second reservoir zone 7 is essentially water. The first and second reservoir zones 6, 7 each has a reservoir pressure of 300 bar. The first inflow device 8 of the first reservoir zone 6 is adjusted to let in the first fluid 10, i.e. oil, so that there is a pressure of 200 bar in the production casing 3. Thereby, there is a pressure difference of 100 bar between the 25 reservoir and the casing. The second inflow device 9 of the second reservoir zone 7 is adjusted to let in the second fluid 11, i.e. water, so that there is a pressure of 250 bar in the production casing 3, i.e. the 200 bar from the first zone and 50 bar from the second zone. Thereby, a there is a pressure difference of 50 bar between the reservoir at the second zone and the production casing. By letting in 30 the second fluid 11, i.e. water, a higher water content is obtained in the production outcome. However, at the same time, a higher volume rate of the production outcome and enhanced lift to the well are achieved. In fact, the energy in the reservoir is utilised for lifting the well instead of using secondary means, such as an artificial lift by means of gas, or adding chemicals, for 35 providing lift.

WO 2013/092945 PCT/EP2012/076541 9 In Fig. 2, the production system has five reservoir zones 6, 7, 13, 14, 15 mutually separated by expandable annular barriers 12. In Fig. 2, the first and second reservoir zones 6, 7 are separated by another reservoir zone 14 having a third fluid 10b with a lower oil content than the first fluid 10. Below the first zone 5 6 furthest away from the well head 5, there is another reservoir zone 13 having a fourth fluid 10a which also has a lower oil content than the first fluid 10. Furthermore, above the second zone 7, there is a fifth zone 15 having a fourth fluid 11a with a lower water content than the second fluid 11. Furthermore, one or more of the additional inflow devices 16, 17, 18 arranged in the other 10 reservoir zones 13, 14, 15, respectively, may also be adjusted to let fluid at certain volume rates into the production casing to enhance the lift in the well and provide an optimum production outcome. Thus, the production system 1 may function in the same manner as described in relation to Fig. 1. 15 Fig. 3 shows a diagram disclosing different relationships between volume rate of the production outcome and pressure. As an example, the diagram has three different curves 19, 20, 21 each representing varying volume rates at a certain pressure. In the example above disclosed in Fig. 1, the first inflow device is positioned at a high volume rate at a pressure lower than that of the second 20 inflow device, and the fluid there-through would therefore follow curve 20. The second device is positioned at a lower volume rate but at a higher pressure, and the fluid there-through will therefore be positioned on curve 21 but not at a volume rate as high as that of the fluid through the first inflow device. From the diagram, it is deducible that a high pressure and a high volume rate, cf. curve 25 21, provide a high production outcome. Fig. 4 shows a cross-sectional view of the inflow device 8 along an axial extension of the inflow device 8 being concentric with the axial extension of the casing. In this embodiment, the inflow device 8 comprises an outer sleeve 22 and an inner 30 sleeve 23, and the inner sleeve 23 may be movable in relation to the outer sleeve 22. The cross-sectional view is taken along a row of inflow openings 24 arranged in the extension of the inflow device 8. In this row, there are seven inflow openings 24. The inflow area of the inflow device is inter alia constituted by these inflow openings 24 each having an opening area. If the inflow device 8 has 35 several rows of inflow openings, the total opening area of all these rows provides the total available inflow area of the inflow device. The inflow openings 24 are in fluid connection with the inner opening 25 of the second inner sleeve 23 so that WO 2013/092945 PCT/EP2012/076541 10 fluid from the reservoir may flow in through the inflow device 8. In this embodiment, the inner opening 25 is shown as a through-going groove extending in the axial extension of the inflow device 8. The inner opening 25 has a larger extension than the inflow openings 24 to ensure that the inner opening 25, when 5 being aligned with the inflow openings, does not prevent the fluid from flowing. A screen 26 or filter is arranged on the outside of the inflow openings. Another embodiment of the inflow device 8 is shown in Fig. 5 in a cross-sectional view along an axial extension of the inflow device 8. The inflow device 8 also 10 comprises the outer sleeve 22 and the inner sleeve 23 which are movable in relation to each other. The inflow openings 24 are in fluid connection with the inner openings 25 of the second inner sleeve 23 to allow fluid from the reservoir to flow in through the inflow device 8. In this embodiment, the inner openings 25 are shown as seven through-going holes being aligned with the inflow openings 15 24 of the outer sleeve. The inner openings 25 have a larger extension than each of the inflow openings 24 so they do not prevent the fluid from flowing. Again, a screen 26 or filter is arranged on the outside of the inflow openings 24. An additional embodiment of the inflow device 8 is shown in Fig. 6 in a cross 20 sectional view along a row of inflow openings 24 arranged in the extension of the inflow device 8. The inflow openings 24 terminate in an axially extending channel 27 arranged in the wall of the outer sleeve 22. The axial channel 27 abuts an axial channel 55 arranged in the inner sleeve 23, whereby the inflow openings 24 are in fluid communication with the inner opening 25 via the two axial channels 25 27, 55, respectively. Also, in this embodiment, a screen 26 or filter is arranged on the outside of the inflow openings 24. The embodiment of the inflow device 8 shown in Fig. 6 will be described further in connection with Fig. 9 below. The inflow device 8 of Fig. 4 is shown in perspective in Fig. 7. The inflow device 8 30 comprises the outer sleeve 22 and the inner sleeve 23, wherein the inner sleeve 23 is movable in relation to the outer sleeve 22 by rotation. Four rows of inflow openings 24, 28, 29, 30 are arranged adjacent to each other and along the axial extension of the inflow device 8. The first row has seven inflow openings 24, as shown in the cross-sectional view in Fig. 4. The second row has six inflow 35 openings 28. The third row has four inflow openings 29, and the fourth row has two inflow openings 30.The inflow openings 24, 28, 29, 30 of the four rows constitute the inflow area of the inflow device 8.

WO 2013/092945 PCT/EP2012/076541 11 In other embodiments, the inflow device may have a different number of rows and a different number of inflow openings in each row. Thus, the embodiment shown in Fig. 7 is one configuration of the inflow device 8. 5 The inner sleeve 23 is shown in Fig. 7 with four inner openings 25 visible in cross-section, and the openings 25 are each aligned with an inflow opening in the row of inflow openings 24 arranged in the outer sleeve 22. Also, the inflow device 8 may have a different number of inner openings and different positions along the periphery of the inner sleeve. 10 Figs. 8a to 8o show a sequence of different adjustments to different positions of the inflow device in relation to the desired inflow volume rate of the inflow device 8. 15 In the same manner as described above, the inflow device 8 comprises an inner sleeve 23 or tubular which is rotatable within the outer sleeve 22 or tubular. The inflow device 8 is shown in a cross-sectional view of a radial extension of the inflow device 8. The outer sleeve 22 has four rows of inflow openings, 24, 28, 29, 30. In the first row 24, there are seven inflow openings, as shown in Fig. 7, in the 20 second row 28, there are six openings, in the third row 29, there are four openings, and in the fourth row, there are two openings. In Fig. 8a, the inner sleeve 23 has ten inner openings 25, 31, 32, 33, 34, 35, 36, 37, 38, 39 in the form of grooves, the grooves are shown in Fig. 4, and the openings are arranged along the periphery of the inner sleeve 23. The inner openings 25, 31, 32, 33, 25 34, 35, 36, 37, 38, 39 are arranged with predetermined distances between them so that each row of outer inflow openings 24 can optionally be opened or closed by rotating the inner sleeve 23, which will be further described below. In Fig. 8a, the rows of inflow openings 24, 28, 29, 30 are all aligned with the 30 inner openings 31, 32, 33, 34 of the inner sleeve 23. Thus, in Fig. 8a, all inflow openings 24, 28, 29, 30 of the inflow device 8 are open, whereby fluid may flow through all nineteen openings. This is the maximum flow capacity of the inflow device 8. 35 In Fig. 8b, the inner sleeve 23 is rotated slightly to the right, whereby the inner opening 25 is aligned with the first row of inflow openings 24, the inner opening 31 is aligned with the row of inflow openings 29, and the inner opening 32 is WO 2013/092945 PCT/EP2012/076541 12 aligned with the row of inflow openings 30. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 24, 29, 30 are open and the row of inflow openings 28 is closed, resulting in thirteen openings being open. By rotating the inner sleeve even further so that the inner opening 25 is aligned with the third 5 row of inflow openings 29, four openings are open, and by rotating the inner sleeve even further so that the inner opening 25 is aligned with the fourth row of inflow openings 30, two openings are open. In Fig. 8c, the inner sleeve 23 is rotated slightly to the left, whereby the inner 10 opening 31 is aligned with the row of inflow openings 28, the inner opening 32 is aligned with the row of inflow openings 29, and the inner opening 33 is aligned with the row of inflow openings 30. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 28, 29, 30 are open and the row of inflow openings 24 is closed, resulting in twelve openings being open. 15 In Fig. 8d, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8c, whereby the inner opening 32 is aligned with the row of inflow openings 24, the inner opening 33 is aligned with the row of inflow openings 28, and the inner opening 34 is aligned with the row of inflow openings 20 29. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 24, 28, 29 are open and the row of inflow openings 30 is closed, resulting in seventeen openings being open. In Fig. 8e, the inner sleeve 23 is rotated slightly to the left in relation to the 25 adjustment of Fig. 8d, whereby the inner opening 33 is aligned with the row of inflow openings 24, the inner opening 34 is aligned with the row of inflow openings 28, and the inner opening 35 is aligned with the row of inflow openings 30. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 24, 28, 30 are open and the row of inflow openings 29 is closed, resulting in 30 fifteen openings being open. In Fig. 8f, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8e, whereby the inner opening 34 is aligned with the row of inflow openings 24 and the inner opening 35 is aligned with the row of inflow 35 openings 29. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 24, 29 are open and the rows of inflow openings 28, 30 are closed, resulting in eleven openings being open.

WO 2013/092945 PCT/EP2012/076541 13 In Fig. 8g, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8f, whereby the inner opening 35 is aligned with the row of inflow openings 28. Thus, by this adjustment of the inflow device 8, the row of inflow openings 28 are open and the rows of inflow openings 24, 29, 30 are 5 closed, resulting in six openings being open. In Fig. 8h, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8g, whereby the inner opening 35 is aligned with the row of inflow openings 24 and the inner opening 36 is aligned with the row of inflow 10 openings 30. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 24, 30 are open and the rows of inflow openings 28, 29 are closed, resulting in nine openings being open. In Fig. 8i, the inner sleeve 23 is rotated slightly to the left in relation to the 15 adjustment of Fig. 8h, whereby the inner opening 36 is aligned with the row of inflow openings 28 and the inner opening 37 is aligned with the row of inflow openings 30. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 28, 30 are open and the rows of inflow openings 24, 29 are closed, resulting in eight openings being open. 20 In Fig. 8j, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8i, whereby the inner opening 36 is aligned with the row of inflow openings 24 and the inner opening 37 is aligned with the row of inflow openings 29. Thus, by this adjustment of the inflow device 8, the rows of inflow 25 openings 24, 29 are open and the rows of inflow openings 28, 30 are closed, and this adjustment thus results in the same position as in Fig. 8f. In Fig. 8k, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8j, whereby the inner opening 38 is aligned with the row of 30 inflow openings 29 and the inner opening 39 is aligned with the row of inflow openings 30. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 29, 30 are open and the rows of inflow openings 24, 28 are closed, resulting in six openings being open. 35 In Fig. 81, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8k, whereby the inner opening 38 is aligned with the row of inflow openings 28 and the inner opening 39 is aligned with the row of inflow WO 2013/092945 PCT/EP2012/076541 14 openings 29. Thus, by this adjustment of the inflow device 8, the rows of inflow openings 28, 29 are open and the rows of inflow openings 24, 30 are closed, resulting in ten openings being open. 5 In Fig. 8m, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 81, whereby the inner opening 38 is aligned with the row of inflow openings 24 and the inner opening 39 is aligned with the row of inflow openings 28. Thus, in this adjustment of the inflow device 8, the rows of inflow openings 24, 28 are open and the rows of inflow openings 29, 30 are closed, 10 resulting in thirteen openings being open. In Fig. 8n, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8m, whereby the inner opening 39 is aligned with the row of inflow openings 24. Thus, by this adjustment of the inflow device 8, the rows of 15 inflow openings 24 are open and the rows of inflow openings 28, 29, 30 are closed, resulting in seven openings being open. In Fig. 8o, the inner sleeve 23 is rotated slightly to the left in relation to the adjustment of Fig. 8n, whereby all rows of inflow openings 24, 28, 29, 30 are 20 closed. Thus, by this adjustment, the inflow device 8 is closed. The sequence of adjustments shown in Figs. 8a-8o shows different flow capacities of the inflow device 8, resulting in fourteen different volume rates. Even though some possible adjustments of the inflow device 8 are not shown in Figs. 8a-8o, it 25 is evident for the skilled person that the configuration of the inflow device 8 makes it possible to open and close all rows of inflow openings independently of each other by rotating the inner sleeve into the intended position. Fig. 9 shows a longitudinal cross-sectional view of another embodiment of an 30 inflow device 8. The inflow device 8 comprises a first sleeve or tubular 40 having twelve inflow openings 24 in a first wall 41 and twelve first axial channels 27 extending in the first wall 41 from the inflow openings 24 to an outlet 53. By axial channels is meant that the channels extend in an axial direction in relation to the inflow device 8. 35 The inflow device also comprises a second sleeve 42 or tubular having a first end 43 near the outlet 53 and a second end 44 and, in this view, six inner openings WO 2013/092945 PCT/EP2012/076541 15 25. Even though the second sleeve 42 or tubular only shows six inner openings 25, the number of inner openings is actually the same as in the first sleeve 40 or tubular, i.e. 12 inner openings. 5 Furthermore, the second sleeve 42 or tubular is rotatable within the first sleeve 40 or tubular, and the second sleeve 42 has a second wall 45 having twelve second axial channels (not shown) extending in the second wall 45 from the first end 43 to the inner opening 25. Thus, each inner opening 25 has its own second axial channel. 10 The second sleeve 42 or tubular is arranged in an inner circumferential recess 46 in the first wall 41 of the first sleeve 40 or tubular, meaning that when the second sleeve 42 or tubular is arranged in the recess, the second sleeve 42 or tubular will not decrease the overall inner diameter of the inflow device and 15 thereby of the production casing. The second sleeve 42 or tubular is rotatable in relation to the first sleeve 40 or tubular at least between a first position, in which the first channel 27 and second channel (not shown) are aligned to allow fluid to flow from the reservoir into the 20 production casing via the first end 43 of the second sleeve 42 or tubular, and a second position (the position shown in Fig. 9), in which the first channel 27 and second channel (not shown) are not aligned, meaning that fluid is prevented from flowing into the production casing. 25 The inflow device 8 also comprises a first packer 47 which is arranged between the first sleeve 40 or tubular and the first end 43 of the second sleeve 42 or tubular. The packer 47 extends around the inner circumferential recess 46 and has an inner diameter which is substantially the same as that of the second sleeve or tubular. The packer 47 has a number of through-going packer channels 30 48 corresponding to the number of first axial channels, i.e. in this embodiment twelve, the packer channels 48 being aligned with the first axial channels 27. The packer is fixedly connected with the first sleeve or tubular so that the packer channels 48 are fluidly connected with first axial channels. The packer is ring shaped, and the through-going packer channels 48 extend through the packer 35 along the axial extension of the first sleeve or tubular.

WO 2013/092945 PCT/EP2012/076541 16 The packer 47 is preferably made of ceramics, whereby it is possible to make the contact surfaces of the packer 47 smooth, which enhances the sealing properties of the packer 47, since the smooth contact surface may be pressed closer to the opposite surface which is the first end 43 of the second sleeve 42 or tubular. 5 However, in other embodiments, the packer may be made of metal, composites, polymers or the like. Furthermore, a second packer 49 is arranged between the first sleeve 40 or tubular and the second end 44 of the second sleeve 42 or tubular. However, in 10 another embodiment, the second packer is omitted, whereby the second end 44 of the second sleeve 42 or tubular faces the first wall of the first sleeve 40 or tubular. In Fig. 9, a first spring element 50 is arranged between the first packer 47 and 15 the first sleeve 40 or tubular. The spring element 50 thus forces the first packer against the second sleeve 42 to provide a seal therebetween. Furthermore, the second sleeve 42 or tubular may comprise at least one recess 51 accessible from within, the recess 51 being adapted to receive a key tool (not 20 shown) for rotating the second sleeve 42 or tubular in relation to the first sleeve 40 or tubular. The adjustment of the inflow devices 8, 9 may be performed manually, e.g. by inserting a downhole tool having a key tool into the production casing and 25 moving the downhole tool to the inflow device which needs to be adjusted. The inflow devices 8, 9 may also be operated by a magnetic source. The inflow device 8 of Fig. 7 has an inner sleeve 23 rotating in relation to an outer sleeve 22, and in Fig. 10, the inner sleeve 23 slides axially in relation to the 30 outer sleeve 22. The inner sleeve 23 slides in a recess in the outer sleeve 22, as shown in Fig. 11 where the inner sleeve covers three of the four rows shown in Fig. 10, and thus, all the inflow openings 24 except two are covered. The first row comprises eight inflow openings 24, the second row comprises six inflow openings 24, the third row comprises four inflow openings 24, and the fourth row 35 comprises two inflow openings 24. By sliding the sleeve back and forth in the recess along the inner surface of the outer sleeve, the number of inflow openings 24 which the fluid may flow through may be varied in the same manner as in the WO 2013/092945 PCT/EP2012/076541 17 embodiment of the inflow device 8 shown in Fig. 7. In other embodiments of an inflow device having an axially slidable inner sleeve, the inflow device may have a different number of rows and a different number of inflow openings in each row. Thus, the embodiment shown in Figs. 9 and 10 is only one configuration of the 5 inflow device 8. Fig. 1 shows the production casing comprising annular barriers, each annular barrier being adapted for expansion in an annulus 52 between a production casing and an inside wall 54 of a borehole 55 downhole. Each annular barrier 10 comprises a tubular part 57 for mounting as part of the production casing and an expandable sleeve 58 surrounding the tubular part. Each end 59, 60 of the expandable sleeve is fastened to the tubular part by means of a connection part 72. At least one end is slidably connected with the tubular part. The expandable sleeve surrounds the tubular part and defines an annular barrier space 73 15 between the tubular part and the expandable sleeve. The annular barrier further comprises an aperture 71 in the tubular part for letting fluid into the annular barrier space to expand the sleeve. The annular barriers are arranged separating the first reservoir zone 6 and the second reservoir zone 7 so that three annular barriers provide two reservoir zones. The expandable sleeve, the tubular part and 20 the connection parts are made of metal. In other embodiments, the inflow devices may be remotely adjustable, e.g. by wireline or wireless control. 25 The inflow device 8 is adapted to be inserted and form part of the production casing 3, thus forming a cased completion (not shown). Accordingly, the ends of the inflow device 8 are adapted to be connected with another casing element by conventional connection means, for instance by means of a threaded connection. 30 In the embodiments described above, the outer openings are shown as openings per se. However, the outer openings may comprise flow restrictors, throttles or valves, such as inflow control valves (not shown). Even though the above-mentioned embodiments have been described primarily 35 in relation to rotatable movement of the inner sleeve in relation to the outer sleeve, the inner sleeve may be slidably movable in relation to the outer sleeve.

WO 2013/092945 PCT/EP2012/076541 18 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 5 containing fluid, etc. Gas, oil, and water fluids may thus all comprise other elements or substances than gas, oil, and/or water, respectively. By a casing is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production. 10 In the event that the tools are not submergible all the way into the casing, a downhole tractor can be used to push the tools all the way into position in the well. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®. 15 Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims. 20

Claims

1. A production system (1) for producing hydrocarbons from a well (2), comprising: 5 - a production casing (3), - a first reservoir zone (6) comprising at least a first fluid (10), extending along and outside a part of the production casing (3), - a second reservoir zone (7) comprising at least a second fluid (11), extending along and outside another part of the production casing (3), 10 - a first inflow device (8) arranged in the first reservoir zone (6), having a first inflow area and being adapted to let the first fluid (10) into the production casing (3) at a first volume rate (V1), and - a second inflow device (9) arranged in the second reservoir zone (7), having a second inflow area and being adapted to let the second fluid (11) into the 15 production casing (3) at a second volume rate (V2), wherein the first and second inflow areas of the inflow devices (8, 9) are adjustable, whereby the first and second inflow devices (8, 9) can be adjusted so that the first volume rate (V1) is equal to or higher than the second volume rate (V2). 20

2. A production system (1) according to claim 1, wherein the inflow device (8, 9) comprises a first outer sleeve (22) and a second inner sleeve (23) movable in relation to each other, the first outer sleeve (22) having outer inflow openings (24, 28, 29, 30) arranged in rows with a different number of openings in each 25 row, and the second inner sleeve (23) having inner openings (25, 31, 32, 33, 34, 35, 36, 37, 38, 39), whereby the inflow area of the inflow device (8, 9) is adjustable in that the inner openings (25, 31, 32, 33, 34, 35, 36, 37, 38, 39) of the second inner sleeve (23) can be moved and aligned in relation to the outer openings (24, 28, 29, 30) of the first sleeve (22). 30

3. A production system (1) according to claim 2, wherein the inner openings are arranged with a distance between them in relation to the outer openings (24, 28, 29, 30), whereby inflow area of the inflow device (8, 9) is adjustable in that the inner openings (25, 31, 32, 33, 34, 35, 36, 37, 38, 39) of the second inner 35 sleeve (23) can be moved and aligned in relation to the outer openings (24, 28, 29, 30) of the first sleeve (22). WO 2013/092945 PCT/EP2012/076541 20

4. A production system (1) according to claim 2 or 3, wherein the inner openings of the inner sleeve may be arranged with predetermined circumferenctial distances between them so that each row of outer inflow openings can optionally be opened or closed by moving the inner sleeve. 5

5. A production system (1) according to claim 3 or 4, wherein the second inner sleeve (23) is rotatably movable in relation to the first outer sleeve (22).

6. A production system (1) according to any of the preceding claims, wherein 10 the second sleeve comprises recesses 51 for engaging with a key tool for adjusting the inflow device.

7. A production system (1) according to any of the preceding claims, further comprising a monitoring unit (4) adapted to measure a production outcome of 15 the well (2).

8. A production system (1) according to claim 7, wherein the monitoring unit (4) is adapted to measure a water content of the production outcome so that the inflow devices (8, 9) may be adjusted to obtain an optimum between production 20 outcome and water content.

9. A production system (1) according to claim 7 or 8, wherein the monitoring unit (4) is adapted to measure a volume rate of the production outcome and/or a pressure at the top of the well (2) so that the inflow devices (8, 9) may be 25 adjusted based on of the volume rate and/or pressure measured at the top of the well (2).

10. A production system (1) according to any of the preceding claims, wherein the reservoir zones (6, 7) are separated by annular barriers (12). 30

11. A production system (1) according to any of the preceding claims, wherein the first fluid (10) is oil and the second fluid (11) is water or gas.

12. A production system (1) according to any of the preceding claims, wherein 35 the inflow device comprises a first packer (47), the second sleeve is arranged in a recess (46) of the first sleeve, and the first packer is arranged between the first sleeve and the second sleeve. WO 2013/092945 PCT/EP2012/076541 21

13. A production system (1) according to claim 12, wherein the packer extends around the inner circumferential recess (46) and has an inner diameter which is substantially the same as that of the second sleeve. 5

14. A production system (1) according to claim 12 or 13, wherein the packer has a number of through-going packer channels (48) for being aligned with first axial channels (27) in the first sleeve.

15. A production system (1) according to any of claims 12-14, wherein the 10 packer is made of ceramics.

16. A production system (1) according to any of the preceding claims, wherein the production casing comprises annular barriers, each annular barrier being adapted for being expanded in an annulus (52) between the production casing 15 and an inside wall (54) of a borehole (55) downhole, and each annular barrier comprising: - a tubular part (57) for mounting as part of the production casing, - an expandable sleeve (58) surrounding the tubular part, each end (59, 60) of the expandable sleeve being fastened to the tubular part by means of a 20 connection part (72), - an annular barrier space (73) between the tubular part and the expandable sleeve, and - an aperture (71) in the tubular part for letting fluid into the annular barrier space to expand the sleeve, 25 wherein annular barriers are arranged, separating the first reservoir zone (6) and the second reservoir zone (7).

17. A production system (1) according to claim 17, wherein the expandable sleeve is made of metal. 30

18. A well completion comprising the production system (1) according to any of the claims 1 to 15 and a well head (5).

19. A well completion according to claim 18, further comprising a control unit 35 (62) arranged in the well head (5) for adjusting the inflow devices. WO 2013/092945 PCT/EP2012/076541 22

20. A production method for production of hydrocarbons from a well (2), comprising the steps of: - identifying a first reservoir zone (6) comprising at least a first fluid (10), - identifying a second reservoir zone (7) comprising at least a second fluid (11), 5 - opening a first inflow device (8) in the first zone (6) to let the at least first fluid (10) into a production casing (3) at a first volume rate (V1), - opening a second inflow device (9) in the second zone (7) to let the at least second fluid (11) into the production casing (3) at a second volume rate (V2), - monitoring a production outcome of the well (2), and 10 - adjusting the first and second inflow devices (8, 9) based on the production outcome so that the first volume rate (V1) is equal to or higher than the second volume rate (V2) or so that the second volume rate is higher than the first volume rate. 15

21. A method according to claim 20, wherein the monitoring step comprises one or more of the steps of: - measuring a pressure at the top of the well, - measuring a volume rate of the production outcome at the top of the well, and/or 20 - measuring a water content of the production outcome at the top of the well.

22. A method according to claim 20 or 21, wherein the step of adjusting the first and second inflow devices further comprises adjustment of at least one of the inflow devices (8, 9) based on the measured pressure, volume rate and/or 25 water content at the top of the well.

23. A method according to claim 20 or 21, wherein the step of adjusting the first and second inflow devices is performed manually, e.g. by a key tool connected with a downhole tractor. 30