Valve for closing fluid communication between a well and a production string, and a method of using the valve

Abstract

A valve is for closing fluid communication between a horizontal or deviated well and a production string when a content of a first or a second undesired fluid in the fluid flow exceeds a predetermined level. The valve has a primary flow channel, and a piston arrangement movable within the valve between an inactive position allowing fluid flow through the primary channel and an active position preventing fluid flow through the primary channel. The piston arrangement further has a secondary flow channel and a bypass flow channel and inflow control elements exposed to the fluid flow upstream of the flow barrier and having different density and movable within independent paths in response to a density of fluid.

Claims

1. A valve for closing fluid communication between a horizontal or deviated well and a production string when a content of a first or a second undesired fluid in a fluid flow exceeds a predetermined level, the valve comprising: a piston housing; a flow barrier inside the housing; a primary flow channel having a primary inlet through the flow barrier, and a primary outlet; and a piston arrangement movable within the piston housing between an inactive position allowing fluid flow through the primary flow channel and an active position preventing fluid flow through the primary flow channel, wherein the valve further comprises: a secondary flow channel in connection with the primary flow channel, the secondary flow channel having two separate flow paths, each flow path having an inlet through the flow barrier, wherein each flow path of the secondary flow channel is configured for providing a pressure towards the inactive position of the piston arrangement when fluid flows through the secondary flow channel; a bypass flow channel having two inlets through the flow barrier, and a bypass flow channel outlet, the bypass flow channel being configured for providing a pressure towards the active position of the piston arrangement when fluid flows through the bypass flow channel; two inflow control elements for being exposed to the fluid flow upstream of the flow barrier and having different density and being movable within two independent paths between the inlets in response to a density of fluid, wherein a first of the two inflow control elements has a density between a density of a desired fluid and the density of the first undesired fluid, and a second of the two inflow control elements has a density between the density of the desired fluid and the density of the second undesired fluid; wherein the secondary flow channel is open and the bypass flow channel is closed when an amount of one of the first and the second undesired fluid is below the predetermined level, and the piston arrangement is in the inactive position, and wherein, when one of the first and the second undesired fluid exceeds the predetermined level, the inflow control elements are caused to move within their respective paths for closing the secondary flow channel at one of its inlets and for opening the bypass flow channel at one of its inlets, and said opening and closing causing a change in pressure balance within the piston arrangement thereby moving the piston arrangement to the active position wherein the primary flow channel is closed.

2. The valve according to claim 1, wherein the primary inlet is provided with a tube having at least one tube inlet arranged between one of the inlets of the secondary flow channel and the bypass flow channel and the other of the inlets of the secondary flow channel and the bypass flow channel.

3. The valve according to claim 1, wherein the piston arrangement is axially movable within a portion of an annulus defined by: an inner tubular body for being in fluid communication with the production string; a housing arranged coaxially with and surrounding a portion of the inner tubular body; a downstream barrier arranged within the annulus and axially spaced apart from the flow barrier; wherein the annulus further comprises a stationary valve seat arranged between the downstream barrier and the flow barrier so that the a portion of the piston arrangement abuts the valve seat when the piston arrangement is in its active position and the piston arrangement does not abut the valve seat when the piston arrangement is in its inactive position.

4. The valve according to claim 3, wherein the valve seat comprises a first valve seat element and a second valve seat element axially spaced apart from the first valve seat element, a portion of the piston arrangement being movable between the valve seat elements, said portion abutting both valve seat elements when the piston arrangement is in its active position.

5. The valve according to claim 1, wherein the valve is provided with at least one leakage channel being in fluid communication with the bypass flow channel outlet for allowing leakage through the valve when the piston arrangement is in its active position.

6. The valve according to claim 5, wherein the at least one leakage channel comprises a first leakage channel and a second leakage channel being in fluid communication with the first leakage channel via a conduit.

7. The valve according to claim 1, wherein the piston arrangement comprises: a first piston for defining a first piston chamber and a second piston chamber; a second piston for defining a third piston chamber and a fourth piston chamber, wherein the first and second pistons are interconnected by a connection means.

8. The valve according to claim 7, wherein: the secondary flow channel first inlet is in fluid communication with the first piston chamber; the secondary flow channel second inlet is in fluid communication with the third piston chamber, the first piston chamber and the third piston chamber being in fluid communication with the primary flow channel; the bypass flow channel first inlet and the bypass flow channel second inlet are in fluid communication with the second piston chamber and the fourth piston chamber, and wherein the second piston chamber and the fourth piston chamber are in fluid communication with the bypass flow channel outlet.

9. A completion string comprising a valve for closing fluid communication between a horizontal or deviated well and a production string when a content of a first or a second undesired fluid in a fluid flow exceeds a predetermined level, the valve comprising: a piston housing; a flow barrier inside the housing; a primary flow channel having a primary inlet through the flow barrier, and a primary outlet; and a piston arrangement movable within the piston housing between an inactive position allowing fluid flow through the primary flow channel and an active position preventing fluid flow through the primary flow channel, wherein the valve further comprises: a secondary flow channel in connection with the primary flow channel, the secondary flow channel having two separate flow paths, each flow path having an inlet through the flow barrier, wherein each flow path of the secondary flow channel is configured for providing a pressure towards the inactive position of the piston arrangement when fluid flows through the secondary flow channel; a bypass flow channel having two inlets through the flow barrier, and a bypass flow channel outlet, the bypass flow channel being configured for providing a pressure towards the active position of the piston arrangement when fluid flows through the bypass flow channel; two inflow control elements for being exposed to the fluid flow upstream of the flow barrier and having different density and being movable within two independent paths between the inlets in response to a density of fluid, wherein a first of the two inflow control elements has a density between a density of a desired fluid and the density of the first undesired fluid, and a second of the two inflow control elements has a density between the density of the desired fluid and the density of the second undesired fluid; wherein the secondary flow channel is open and the bypass flow channel is closed when an amount of one of the first and the second undesired fluid is below the predetermined level, and the piston arrangement is in the inactive position, and wherein, when one of the first and the second undesired fluid exceeds the predetermined level, the inflow control elements are caused to move within their respective paths for closing the secondary flow channel at one of its inlets and for opening the bypass flow channel at one of its inlets, and said opening and closing causing a change in pressure balance within the piston arrangement thereby moving the piston arrangement to the active position wherein the primary flow channel is closed.

10. A method for controlling fluid flow in, into, or out of a well, wherein the method comprises the steps of: mounting at least one valve as part of a well completion string prior to inserting the string in the well, the valve comprising: a piston housing; a flow barrier inside the housing; a primary flow channel having a primary inlet through the flow barrier, and a primary outlet; and a piston arrangement movable within the piston housing between an inactive position allowing fluid flow through the primary flow channel and an active position preventing fluid flow through the primary flow channel, wherein the valve further comprises: a secondary flow channel in connection with the primary flow channel, the secondary flow channel having two separate flow paths, each flow path having an inlet through the flow barrier, wherein each flow path of the secondary flow channel is configured for providing a pressure towards the inactive position of the piston arrangement when fluid flows through the secondary flow channel; a bypass flow channel having two inlets through the flow barrier, and a bypass flow channel outlet, the bypass flow channel being configured for providing a pressure towards the active position of the piston arrangement when fluid flows through the bypass flow channel; two inflow control elements for being exposed to the fluid flow upstream of the flow barrier and having different density and being movable within two independent paths between the inlets in response to a density of fluid, wherein a first of the two inflow control elements has a density between a density of a desired fluid and the density of the first undesired fluid, and a second of the two inflow control elements has a density between the density of the desired fluid and the density of the second undesired fluid; wherein the secondary flow channel is open and the bypass flow channel is closed when an amount of one of the first and the second undesired fluid is below the predetermined level, and the piston arrangement is in the inactive position, and wherein, when one of the first and the second undesired fluid exceeds the predetermined level, the inflow control elements are caused to move within their respective paths for closing the secondary flow channel at one of its inlets and for opening the bypass flow channel at one of its inlets, and said opening and closing causing a change in pressure balance within the piston arrangement thereby moving the piston arrangement to the active position wherein the primary flow channel is closed; bringing the well completion string into the well; orienting the at least one valve within the well; and flowing fluid out of the well.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein:

(2) FIG. 1 shows a principle sketch of a typical subsea well having a plurality of valves according to the present invention distributed along a horizontal section of the well;

(3) FIG. 2 shows in larger scale a perspective view of a pipe stand comprising a base pipe and a screen, and an apparatus according to the present invention;

(4) FIG. 3a-3h illustrate an important operation principle of the valve according the invention;

(5) FIG. 4a shows an axial cross-section through the valve in an open position, the valve being configured for blocking inflow of water and gas exceeding a predetermined level;

(6) FIG. 4b shows the same as FIG. 4a, indicating positions of various cross-sections through the valve which are shown in FIGS. 4d-4q;

(7) FIG. 4c shows the valve in FIG. 4a when the valve is in a closed position;

(8) FIG. 4d shows a cross-section through A-A of FIG. 4b;

(9) FIG. 4e shows a cross-section through B-B of FIG. 4b;

(10) FIG. 4f shows a cross-section through C-C of FIG. 4b;

(11) FIG. 4g shows a cross-section through D-D of FIG. 4b;

(12) FIG. 4h shows a cross-section through E-E of FIG. 4b;

(13) FIG. 4i shows a cross-section through F-F of FIG. 4b;

(14) FIG. 4j shows a cross-section through G-G of FIG. 4b;

(15) FIG. 4k shows a cross-section through H-H of FIG. 4b;

(16) FIG. 4l shows a cross-section through I-I of FIG. 4b;

(17) FIG. 4m shows a cross-section through J-J of FIG. 4b;

(18) FIG. 4n shows a cross-section through K-K of FIG. 4b;

(19) FIG. 4o shows a cross-section through L-L of FIG. 4b;

(20) FIG. 4p shows a cross-section through M-M of FIG. 4b;

(21) FIG. 4q shows a cross-section through N-N of FIG. 4b;

(22) FIGS. 5a-5c show in a larger scale various views of an inlet tube as shown in FIG. 4d;

(23) FIG. 6 shows a cross-section through R-R of FIG. 4e;

(24) FIG. 7 shows a cross-section through S-S of FIG. 4e;

(25) FIG. 8 shows a cross-section through T-T of FIG. 4e; and

(26) FIGS. 9a-9h shown to the left of each of the FIGS. 3a-3h, respectively, is a vertical cross-section taken at the right portion of two inflow control elements.

DETAILED DESCRIPTION OF THE DRAWINGS

(27) Positional indications such as for example “above”, “below”, “upper”, “lower”, “left”, and “right”, refer to the position shown in the figures.

(28) In the figures, same or corresponding elements are indicated by same reference numerals. For clarity reasons some elements may in some of the figures be without reference numerals.

(29) A person skilled in the art will understand that the figures are just principle drawings. The relative proportions of individual elements may also be strongly distorted.

(30) In the figures, the reference numeral 1 denotes a valve according to the present invention.

(31) FIG. 1 shows a typical use of the valve 1 in a well completion string CS arranged in a substantially horizontal wellbore or well W penetrating a reservoir F. The well W is in fluid communication with a rig R floating in a surface of a sea S. The well W comprises a plurality of zones separated by packers PA, for example so-called swell packers, as will be appreciated by a person skilled in the art. A person skilled in the art will understand that the well W may alternatively be an onshore well.

(32) In FIG. 1, one valve 1 is shown between each pair of packers PA. However, it should be clear that two or more valves 1 will typically be arranged between each pair of packers PA.

(33) FIG. 2 shows a typical arrangement of the valve 1 in a portion of a well completion string CS. The valve 1 is positioned between a basepipe P and a sandscreen SS. In FIG. 2, the valve 1 according to the invention is indicated with broken lines.

(34) The valve 1 may form part of a so-called pipe stand that may have a typical length of approximately 12 meters. However, the valve 1 may also be arranged in a separate pipe unit having for example a length of only 40-50 centimeters. Such a unit may be configured to be inserted between two subsequent pipe stands.

(35) The valve 1 according to the invention is orientation dependent. In the figures, this is indicated by a g-vector.

(36) In order to explain a basic principle of the valve 1 according to the invention, reference is first made to FIGS. 3a-3h. It should be emphasized that the primary purpose of FIGS. 3a-3h is to explain how a position of an axially movable piston arrangement is activated when an undesired fluid, here in the form of water or gas, exceeds a predetermined level. For explanatory reasons, each of the FIGS. 3a-3h comprises multiple cross-sections of the valve 1.

(37) To the left of each of the FIGS. 3a-3h is shown an explanatory FIG. 9a-9h, respectively, showing a vertical cross-section taken at the right portion of two inflow control elements, here shown as balls 30, 30′, and seen in an inclined angle as indicated by the dotted arrow S. The purpose of the FIGS. 9a-9h is to help understanding the principle drawings 3a-3h.

(38) A more detailed description of embodiments of the valve 1 are disclosed in FIG. 4a et seq.

(39) In FIGS. 3a-3h, the valve 1 comprises a primary flow channel 3 having a primary inlet 5 through a flow barrier 7 and a primary outlet 50. The primary flow channel 3 is configured for influencing a pressure of the fluid through the channel 3. In the embodiment shown, the primary flow channel comprises a venturi with a vena contracta portion 5′ for providing a low pressure portion. Fluid flow through the valve 1 for each flow regime is indicated by multiple arrows from the upstream portion of the valve 1 and through the valve 1.

(40) The valve 1 further comprises a secondary flow channel having two separate flow paths, wherein a first flow path has a first inlet 11 and a second flow path has a second inlet 110 through the flow barrier 7, and a secondary flow channel outlet, here in the form of a pilot hole 13 being in fluid communication with a vena contracta portion 5′, i.e. a low pressure portion of the primary flow channel 3. As will be discussed below and shown for example in FIG. 4f, it is preferred that the two paths of the secondary flow channel communicate with the primary flow channel via separate outlets 13, 130 from the flow paths.

(41) The secondary flow channel first inlet 11 and the secondary flow channel second inlet 110 are arranged in two different guiding means or paths 32′ and 32, respectively. for the balls 30′, 30.

(42) The valve 1 further comprises a bypass flow channel having a first bypass flow channel inlet 31 and a second bypass flow channel inlet 310. The bypass flow channel is in fluid communication with a bypass channel outlet 312. In what follows, the term “flow channel” will also be denoted “channel”.

(43) The first bypass channel inlet 31 is arranged in the same path 32 as the secondary flow channel second inlet 110, and the second bypass channel inlet 310 is arranged in the same path 32′ as the secondary flow channel first inlet 11.

(44) The valve 1 is provided with a piston arrangement 20 that comprises a first piston P1 for defining a first piston chamber C1 and a second piston chamber C2 within a piston housing PH, and a second piston P2 for defining a third piston chamber C3 and a fourth piston chamber C4 within the piston housing PH. The first and second pistons P1, P2 are interconnected by a connection means here in the form of rods R (shown in FIGS. 3a-3h). The rods R also connect the pistons with other parts of the piston arrangement 20, as shown by two rods extending downstream of the second piston P2.

(45) The secondary flow channel first inlet 11 is in fluid communication with the first piston chamber C1, thereby forming part of one of the two flow paths of the secondary flow channel, and the secondary flow channel second inlet 110 is in fluid communication with the third piston chamber C3 by means of a third piston chamber channel C110, thereby forming part of the other one of the two flow paths of the secondary flow channel. The first piston chamber C1 and the third piston chamber C3 are in fluid communication with the primary flow channel 3 at the outlet or pilot hole 13, and preferably outlet 130 (see FIG. 4f) of the vena contracta portion 5′, respectively.

(46) The bypass channel first inlet 31 and a bypass channel second inlet 310 are in fluid communication with the second piston chamber C2 and the fourth piston chamber C4 by means of a second piston chamber channel C31 and a fourth piston chamber channel C310, respectively.

(47) The second piston chamber C2 and the fourth piston chamber C4 are in fluid communication with the bypass channel outlet 91 via channels C21 and C41, respectively.

(48) In the embodiment shown, the valve 1 further comprises a first leakage channel 52 and a second leakage channel 54. The first leakage channel 52 is provided with a vena contracta for providing an underpressure therein.

(49) The second leakage channel 54, the channel C21 and the channel C41 merge with the first leakage channel 52 at the vena contracta of the first leakage channel 52. This merging point will hereinafter be denoted tee T.

(50) Although not specifically shown in FIGS. 3a-3g, it should be clear that a hydraulic resistance of the secondary outlet 13, or the pilot hole, is larger than the hydraulic resistance of the secondary flow channel first and second inlets 11, 110. Similarly, it should be clear that a hydraulic resistance of the channels entering tee T is larger than the hydraulic resistance of the bypass channel first and second inlets 31, 310, respectively, and the inlets of the leakage channels 52, 54.

(51) The bypass channel outlet 312 is closable by a bypass channel closing element 21 forming part of the piston arrangement 20. The bypass channel outlet 312 is closed when the primary flow channel 3 is open, i.e. when the piston arrangement 20 is in its inactive position.

(52) The piston arrangement 20 is further provided with a primary channel closing element 23 for closing the outlet of the primary flow channel 3 when the piston arrangement 20 is in its active position. The primary channel closing element 23 is further configured to enclose a periphery of the bypass channel outlet 312 when the piston arrangement 20 is in its active position. The primary channel closing element 23 is provided with an annular cavity 42 forming a conduit (indicated in principle by dotted line 44) for allowing a fluid communication from the bypass channel outlet 312 to a closing element outlet 23′ when the piston arrangement 20 is in its active or closed position.

(53) In what follows, a working principle of the valve 1 will be explained for various fluid situations that are likely to occur in an oil producing well. In the various fluid situations, it is assumed that the valve 1 will be subjected to either a single phase of fluid, i.e. oil, water or gas, or two phases simultaneously, i.e. oil and water, or oil and gas. Further, the fluid will not “switch” directly from water to gas or from gas to water. Oil is always one of the two fluids involved. Those assumptions will be appreciated by a person skilled in the art.

(54) The inflow control elements 30, 30′ are shown as balls. The first inflow control element 30 of the two inflow control elements 30, 30′ has a density between that of oil and gas. For simplicity, the first inflow control element will hereinafter also be denoted “the light ball 30”. The second inflow control element 30′ has a density between that of oil and water and will hereinafter also be denoted “the heavy ball 30”.

(55) Turning now to FIG. 3a, the fluid flowing through the valve is a single-phase oil drained from for example the reservoir F as shown in FIG. 1. In this situation, the piston arrangement 20 is in the inactive or open position, i.e. to the leftmost position. The light ball 30 is in the upper position in the first path 32 blocking bypass flow channel first inlet 31. The heavy ball 30′ is in the lower position in the second path 32′ blocking the secondary flow channel second inlet 310.

(56) The oil flows through the valve 1 via the primary flow channel 3 comprising the vena contracta 5′ and an expansion portion 5″ downstream of the vena contracta 5′. Oil also flows from the secondary flow channel first inlet 11 and second inlet 110 via chamber C1 and C3, respectively, and via the secondary flow channel pilot hole 13 into the primary flow channel 3. As will be explained in more detail below, it is preferred that the fluid flows from chamber C3 into the primary flow channel 3 via a separate inlet 130 as shown for example in FIGS. 4a-4c and FIG. 4f.

(57) There is no flow out of the bypass channel outlet 312, and consequently there is no flow in the second piston chamber C2 and fourth piston chamber C4.

(58) Due to the restriction at the secondary flow channel outlet or pilot hole 13, there is high pressure in chambers C1 and C3. There is also high pressure in chambers C2 and C4 because the pressure immediately upstream of the barrier 7 propagates through the tee T into chambers C2 and C4. By high pressure is meant a pressure substantially corresponding to the pressure immediately upstream of the barrier 7. Consequently, with high pressure in all four chambers C1, C2, C3 and C4, fluid pressure is equalized across the balls 30, 30′.

(59) Upstream of the barrier 7 there is a fluid having a high pressure. In the vena contracta portion 5′ of the primary flow channel 3, there will be a low pressure. In a producing well that is in fluid communication with a downstream portion of the primary flow channel 3, a partial pressure recovery will exist downstream of the venturi that comprises the vena contracta portion 5′. The partial pressure recovery will result in a medium fluid pressure downstream of the venturi. Due to the hydraulic resistance of the pilot hole 13 being larger than the hydraulic resistance of the secondary flow channels inlets 11, 110, a high pressure will exist also in the chambers C1 and C3 forming part of the secondary flow channel 9. Thus, there will be a pressure difference across the valve 1 which urges the piston arrangement 20 to the left. In this position, the piston arrangement 20 does not close the primary flow channel 3 as will be explained in more details from FIG. 4a et seq.

(60) The terms high pressure, medium pressure and low pressure denote mutual relative fluid pressures upstream of and within the valve 1.

(61) Thus, due to the vena contract 5′ of the primary flow channel 3 providing a pressure difference across the valve 1, a small net force will keep the piston arrangement 20 in its inactive open position as shown.

(62) FIG. 3b shows a situation wherein water has started to flow through the valve 1, but before the valve 1 is closed.

(63) The limiting water fraction above which the valve 1 closes, depends on the diameter ratio of the secondary outlet or pilot hole 13 and vena contracta 5′. If it is preferred that the valve 1 closes at a high water cut, for example above 80%, the secondary flow channel outlet 13 should have a small diameter, such as for example 1 mm. If a small diameter represents an unacceptable risk of particle blockage, the secondary outlet 13 can alternatively be replaced by a long circular tube with the smallest acceptable diameter. By making the tube sufficiently long, for example by winding it helically around the barrel P, the limiting water fraction can become very close to 100%.

(64) For low water fractions, for example 10%, all the water will flow through the secondary flow channel second inlet 310.

(65) As the water fraction increases, the water level upstream of the barrier 7 and heavy ball 30′ will ascend to the inlet level of the inlet tube 57. For even higher water fractions, for example above 90%, the water level and heavy ball 30′ will ascend further until it blocks the secondary flow channel first inlet 11 as shown in FIG. 3b.

(66) As the secondary flow channel first inlet 11 has now been blocked by the heavy ball 30′, the low pressure in vena contracta 5′ will immediately propagate into chamber C1, but the pressure in the other three piston chambers C2, C3 and C4 is still high. A net pressure force will therefore urge the piston arrangement to the right as indicated by the arrow shown on the piston arrangement and bring the piston arrangement 20 to its active position, as shown in FIG. 3c.

(67) In FIG. 3c, the water flows through the tee T, entering from the first leakage channel 52, the second leakage channel 54, channel C21 from the second piston chamber C2 and channel C41 from the fourth piston chamber C4. There is no flow through the secondary flow channel pilot hole 13 because the primary outlet 50 of the primary flow channel 3 is closed by the closing element 23.

(68) Thus, in the single-phase water situation shown in FIG. 3c, there is high pressure in all four chambers C1, C2, C3 and C4. A small net force will keep the piston arrangement 20 in its closed position due to a pressure communication channel 46 and an annular cavity 42. This is explained below when discussing for example FIG. 4c.

(69) In the situation shown in FIG. 3c, the pressure across the heavy ball 30′ is equalized, while the pressure across the light ball 30 is substantially equalized.

(70) FIG. 3d illustrates a situation where oil starts coming back, but before the valve 1 reopens. For low oil fractions, for example less than 10%, all oil will flow through the inlet of first leakage channel 52 at the top portion of the restriction 7. As the oil fraction increases, for example to 40%, the water level and the heavy ball 30′ will descend to bypass channel second inlet 310. The second piston chamber C2 and the fourth piston chamber C4 will then be subjected to a low pressure propagating from the tee T, while the first piston chamber C1 and the third piston chamber C3 will be subjected to a high pressure. Thus, a net pressure force will start urging the piston arrangement from the right, i.e. active position, to the left, i.e. inactive position as indicated by the arrow shown on the second piston, until the primary flow channel 3 is open as shown in FIG. 3e (and also in the identical FIG. 3a).

(71) When the valve 1 has been closed due to water or gas, as shown in FIG. 3c and FIG. 3d, respectively, the pressure regime within the valve 1 will be equalized with the pressure upstream of the valve 1, including the pressure across the inflow control elements 30, 30′, i.e. the light ball 30 and heavy ball 30′. The only exception is the annular cavity 42, which is in pressure communication with the outlet 23′ and therefore contributes to keeping the valve closed.

(72) FIG. 3f shows a situation wherein gas, in addition to oil, starts flowing through the valve 1. For low gas fractions, for example less than 10% gas, all the gas will flow through the secondary flow channel first inlet 11. As the gas fraction increases, the oil level and the light ball 30 will descend to the inlet level of the inlet tube 57. As the gas fraction increases further, for example above 75% the oil level and the light ball 30 will descend further until the light ball 30 blocks the secondary flow channel second inlet 110, as shown in FIG. 3f. When the secondary flow channel second inlet 110 is blocked by the light ball 30 while at the same time the heavy ball 30′ blocks the bypass channel second inlet 310, there will be a low pressure in the third piston chamber C3 and high pressure in the other three chambers C1, C2 and C4. A net pressure force will therefore urge the piston arrangement towards right as indicated by the arrow near the second piston P2, until the piston arrangement 20 is in its active or closed position as shown in FIG. 3g.

(73) In FIG. 3g the light ball 30 and the heavy ball 30′ will be in a lowermost position within their respective paths 32, 32′, blocking secondary flow channel inlet 110 and bypass flow channel second inlet 310, respectively. Gas leaks through the tee T, entering from the first leakage channel 52, the second leakage channel 54, channel C21 from the second piston chamber C2 and channel C41 from the fourth piston chamber C4. There is no flow through the secondary flow channel pilot hole 13 because the primary outlet 50 of the primary flow channel 3 is closed by the closing element 23. The leakage of gas through the tee T is due to the annular cavity 42 forming the conduit (indicated by dotted lines) 44 in the primary channel closing element 23 wherein the conduit 44 provides fluid communication between the bypass channel outlet 312 and the closing element outlet 23′. Due to this leaking of gas, the valve 1 is capable of reopening if/when oil starts coming back, as shown in FIG. 3h.

(74) For low oil fractions, for example less than 20%, the oil will flow through the second leakage channel 54 arranged at a lower portion of the restriction 7. As the oil fraction increases, for example to 50%, the oil level and the light ball 30 will start to ascend until it blocks the bypass flow channel first inlet 31, as shown in FIG. 3h. Then, there will be a low pressure in the second piston chamber C2 and in the fourth piston chamber C4, and a high pressure in the first piston chamber C1 and the third piston chamber C3. A net pressure force will therefore urge the piston arrangement 20 towards left until the piston arrangement is in its inactive or open position as shown in FIGS. 3a and 3e. In this situation, the pressure across the light ball 30 and heavy ball 30′ is equalized.

(75) Both in their first position and the second position the inflow control elements 30, 30′, i.e. the light ball 30 and heavy ball 30′, are located at a distance from the inlet level of the inlet tube 57 which is connected to primary inlet 5 of the primary flow channel 3. Thus, the inflow control elements 30, 30′ will not be subject to a stratified flow that may occur at the inlet tube 57, and the inflow control elements 30, 30′ will not “disturb” or provide an obstruction to the fluid flowing into the primary flow channel 3.

(76) From the embodiment shown in FIGS. 3a-3h it should be understood that each flow path of the secondary flow channel is configured for providing a pressure towards the inactive (i.e. left) position of the piston arrangement 20 when fluid flows through the inlets 11, 110 of the secondary flow channel, and that the bypass flow channel is configured for providing a pressure towards the active (i.e. right) position of the piston arrangement 20 when fluid flows through at least one of the inlets 31, 310 of the bypass flow channel and one of the inlets 11, 110 is closed.

(77) The above should explain the basic feature of the valve 1 according to an embodiment of the present invention wherein the valve 1 is configured for opening “on the fly” after being closed.

(78) In what follows, the invention will be explained in more details.

(79) FIGS. 4a-4q show an example of a valve 1 according to the present invention configured for closing for undesired fluids such as for example water and gas, and to reopen when a desired fluid, such as for example oil comes back. The valve 1 comprises similar elements as discussed above with regards to FIGS. 3a-3h. Some of the elements already discussed in FIGS. 3a-3h may therefore not be thoroughly discussed in what follows.

(80) The valve 1 is designed for closing inflow of a fluid from the well W shown in FIG. 1. The valve 1 may typically be arranged as shown in principle in FIG. 2. In the embodiment shown in FIG. 4a, the valve 1 is in an open position and configured for blocking inflow of undesired fluids in the form of water and gas exceeding a predetermined level. As indicated above, undesired water and undesired gas will not occur simultaneously. FIG. 4c shows the valve 1 when closed.

(81) The valve 1 is arranged in an annular space defined between an inner barrel P, such as for example a basepipe that may form part of or be connected to a production string PS of a petroleum well W (see FIG. 1), an outer housing H enclosing a portion of the inner barrel P, an upstream barrier 7 and a downstream barrier 7′.

(82) The barrel P is provided with an aperture 35 for allowing fluid communication from the valve 1 and into the production string PS (as shown in FIGS. 1 and 2). The aperture 35 is arranged upstream of the downstream barrier 7′ and downstream of the piston arrangement 20.

(83) The valve 1 shown in FIGS. 4a-4q comprises an annular piston arrangement 20 axially movable between a first position and a second position. The axial movement of the piston arrangement 20 is limited by a first valve seat 40 and a second valve seat 40′ as will be explained below.

(84) FIG. 4a shows an axial cross-section taken along a longitudinal direction of the valve 1 in an open position, i.e. with the piston arrangement in an inactive position. It should be noted that FIG. 4a is a cross-section through Q-Q of FIG. 4e.

(85) FIG. 4b shows the same as FIG. 4a, but without reference numerals. The purpose of FIG. 4b is to indicate positions of various cross-sections shown in FIGS. 4d-4q.

(86) FIG. 4c shows the valve in FIG. 4a with the piston arrangement 20 in an active or closed position. The piston arrangement 20 comprises a first piston P1 forming an axially movable wall between a first piston chamber C1 and a second piston chamber C2, and a second piston P2 forming an axially movable wall between a third piston chamber C3 and a fourth piston chamber C4. The pistons P1 and P2 are interconnected by means of rods R as best seen in FIG. 8.

(87) As discussed in relation to FIGS. 3a-3h, and as shown in FIGS. 6 and 7, the piston chambers C1, C2, C3 and C4 are in fluid communication with respective ones of inlets 11, 31, 310 and 110 through the restriction 7.

(88) The piston arrangement 20 comprises a bypass channel closing element 21 and a primary channel closing element 23.

(89) In an inactive or open position of the piston arrangement 20, the bypass channel closing element 21 is configured for closing a bypass channel outlet 312 arranged in a top portion of the first valve seat element 40.

(90) In a lower portion, the first valve seat element 40 is provided with a slit 314 extending along an outside portion of the inner barrel P. The oblong slit 314 is best seen in FIG. 4o and FIG. 4p. The slit 314 provides a fluid path for fluid flowing from the primary flow channel 3 when the piston arrangement 20 is in its inactive or open position.

(91) The valve 1 is provided with a pressure-controlled mechanism for providing a pressure differential across a portion of the piston arrangement 20 when the piston arrangement 20 abuts the first valve seat 40. The pressure-controlled mechanism is responsive to a difference in fluid pressure upstream and downstream of the valve 1, so that a closing force of the valve 1 is added to the piston arrangement 20 when said difference in fluid pressure is positive. One purpose of the pressure-controlled mechanism is to facilitate in keeping the valve 1 closed. Another purpose is to facilitate reopening of the valve 1.

(92) In the embodiment shown in FIG. 4a, the pressure-controlled mechanism comprises an annular cavity 42 formed in a portion of the primary channel closing element 23 facing the first valve seat 40. However, it should be clear that the annular cavity 42 in an alternative embodiment could be formed in both the primary channel closing element 23 and the first valve seat 40, or in the first valve seat 40 only. The point is to create an annular cavity 42 between the first valve seat 40 and the primary channel closing element 23 when abutting each other.

(93) The annular cavity 42 is in fluid communication with the aperture 35 in the barrel P via a piston conduit 240 protruding in an axial downstream direction from the primary channel closing element 23. The piston conduit 240 extends through an aperture in the second valve seat element 40′.

(94) When the piston arrangement 20 is in its active or closed position as shown in FIG. 4c, a distant end portion 242 of the piston conduit 240 abuts a periphery of the aperture in the second valve seat element 40′. As indicated in FIG. 4a-4c, the distant end portion 242 is provided with a sealing element.

(95) The first valve seat element 40 is further provided with a pressure communication channel 46 for providing fluid communication between the primary flow channel 3 and an annular conduit chamber 48 defined by the barrel P, the housing H, the second valve seat element 40′, the primary channel closing element 23 and a portion of the first valve seat element 40.

(96) The purpose of the piston conduit 240 is to provide a pressure within the cavity 42 that is lower than the pressure within the conduit chamber 48. Such a pressure differential will arise due to the fact that the cavity 42 is in fluid communication with the fluid flowing within the barrel P, while the fluid pressure within the conduit chamber 48 is in fluid communication with the high-pressure fluid at the inlet 5 of the valve 1. Thus, the pressure differential will result in a net pressure force on the piston arrangement 20 in an upstream direction, which increases the pressure toward the first valve seat element 40 and the second valve seat element 40′.

(97) The annular cavity 42 in the primary flow channel closing element 23 provides a conduit 44 (indicated by a dotted line in FIGS. 3a-3h) for allowing a fluid communication from the bypass channel outlet 312 to the outlet of the distant end portion 242 of the piston conduit 240 when the piston arrangement 20 is in its active or closed position.

(98) The purpose of the annular cavity 42 (providing conduit 44) is to provide a leakage that will make the valve 1 capable of re-opening if gas or water for example in a near-wellbore region retreats and is replaced by oil.

(99) In the embodiment shown, the valve 1 further comprises a first leakage channel 52 and a second leakage channel 54. The first leakage channel 52 is provided with a vena contracta for providing an underpressure therein. The vena contracta is provided at the tee T, as indicated in FIGS. 4a-4c.

(100) The second leakage channel 54 is in fluid communication with the first leakage channel 52 via a conduit 53 (see FIG. 4m) having a leakage conduit inlet 54′ at an end portion of the second leakage channel 54 and a leakage channel outlet in a vena contracta portion of the first leakage channel 52. As mentioned above in connection with FIGS. 3a-3g, a channel C21 from the second piston chamber C2 and a channel C41 from the fourth piston chamber 41 merge at the vena contracta of the first leakage channel 52, i.e. at the tee T.

(101) As indicated in FIGS. 4a and 4c, the secondary flow channel outlet or pilot hole 13 is provided with a funnel-shaped inlet portion. Such an inlet portion is favourable as the effective flow area then becomes substantially the same as the smallest cross-section of the secondary outlet 13. A discharge coefficient of the secondary outlet 13 (the pilot hole) will then be close to one, thereby removing its sensitivity to Reynolds number. The pilot hole 13 provides fluid communication between the first piston chamber C1 and the primary flow channel 3.

(102) In the vena contracta 5′ of the primary flow channel 3 there is provided an inlet 130 of a conduit 131 (see FIGS. 4f and 6) for providing fluid communication between the primary flow channel 3 and the third piston chamber C3. The inlet 130 will also be denoted a pilot hole 130.

(103) The inlet 5 of the primary flow channel 3 is connected to an inlet tube 57 having, in a position of use, an inlet arranged at a higher elevation than the elevation of the primary flow channel. This has an effect of allowing a closing of the valve for both the first and second undesired fluids, such as for example water in one situation and gas in another situation. The arrangement of the inlet tube 57 is shown in FIG. 4d which will now be discussed.

(104) FIG. 4d is a cross-sectional view through A-A of FIG. 4b, i.e. taken upstream of the inlet tube 57. In the embodiment shown, the inlet tube 57 is provided with two inlets 59, 59′ arranged at an elevation being lower than the secondary flow channel first inlet 11 and the bypass channel first inlet 31, but higher than the secondary flow channel second inlet 110 and the bypass channel second inlet 310, both of which are hidden behind the inlet tube 57 in FIG. 4d. Various views of the inlet tube 57 itself are shown in larger scale in FIGS. 5a-5c.

(105) In the embodiment shown in FIG. 4d, the first inflow control element or light ball 30 and the second inflow control element or heavy ball 30′ are not shown. Thus, the light ball 30 and heavy ball 30′ may be at the secondary flow channel second inlet 110 and the bypass channel second inlet 310, meaning that the piston arrangement 20 is in its active position blocking for gas exceeding a predetermined level.

(106) FIG. 4e is a cross-sectional view through B-B of FIG. 4b, i.e. taken upstream of the barrier 7 and downstream of a vertical portion of the inlet tube 57. For an illustrative purpose, the light ball 30 and the heavy ball 30′ are shown at a position being within the paths 32, 32′, respectively, between the bypass channel first inlet 31 and secondary flow channel second inlet 110, and the secondary flow channel first inlet 11 and bypass channel second inlet 310. The inlets of the first leakage channel 52 and second leakage channel 54 are also shown, as well as the primary flow channel inlet 5 provided by the inlet tube, and the vena contracta portion 5′ of the primary flow channel 3.

(107) FIG. 4f is a cross-sectional view through C-C of FIG. 4b. This figure shows a third piston chamber channel C110 for providing fluid communication between the secondary flow channel second inlet 110 and the third piston chamber C3, a second piston chamber channel C31 for providing fluid communication between the bypass channel first inlet 31 and the second and fourth piston chambers C2, C4, and a fourth piston chamber channel C310 for providing fluid communication between the bypass channel second inlet 310 and the second and fourth piston chambers C2, C4. Aperture A31 for providing said fluid communication between the second piston chamber channel C31 and the second piston chamber C2, and aperture A310 for providing said fluid communication between the fourth piston chamber channel C310 and the second piston chamber C2, are shown in FIGS. 3a-3g and in FIG. 4h.

(108) FIG. 4f further shows the pilot hole 13 providing fluid communication between the first piston chamber C1 and the primary flow channel 3, and conduit 131 and inlet 130 for providing fluid communication between the primary flow channel 3 and the third piston chamber C3. Thus, the inlet 130 is also a pilot hole into the primary flow channel 3. Preferably, the inlet 130 at the vena contracta 5′ is independent of the pilot hole 13 at the vena contracta 5′, but the pilot holes 13, 130 have a common outlet pressure which is the pressure in the vena contracta 5′. The independency of the pilot holes 13, 130 facilitates a tailormade design for achieving a desired closing-water fraction and closing-gas fraction being independent of each other. In an embodiment wherein for example such an independent design is not required, the two pilot holes may alternatively be interconnected prior to entering the vena contracta 5′.

(109) FIG. 4g is a cross-sectional view through D-D of FIG. 4b and shows i.a. the piston chamber channels C110, C31 and C310 discussed above in relation to FIG. 4f.

(110) FIG. 4h is a cross-sectional view through E-E of FIG. 4b and shows i.a. two rods R connecting the first piston P1 with the second piston P2 so that pistons P1, P2 are interconnected. The arrangement of the rods R is best seen in FIG. 8. The rods R are also shown in principle in FIGS. 3a-3h, but there as three separate rods. In FIG. 4h is also shown the apertures A31, A310 mentioned above in connection with FIG. 4f. The rods R further connect the pistons P1, P2 with the bypass channel closing element 21 and the primary channel closing element 23′, as shown in FIGS. 4i, 4j, 4l-4n, 4p and 4q.

(111) In FIG. 4h is also shown the channel C21 from the second piston chamber C2.

(112) FIG. 4i is a cross-sectional view through F-F of FIG. 4b and shows i.a. the second piston chamber channel C31 and the fourth piston chamber channel C310.

(113) FIG. 4j is a cross-sectional view through G-G of FIG. 4b and shows i.a. the conduit 131 (as best seen in FIGS. 4f and 6) being in fluid communication with the third piston chamber C3.

(114) FIG. 4k is a cross-sectional view through H-H of FIG. 4b and shows i.a. the second piston P2 and the second piston chamber channel C31 and fourth piston chamber channel C310 extending therethrough.

(115) FIG. 4l is a cross-sectional view through Hof FIG. 4b and shows i.a. the vena contracta portion of the first leakage channel 52 and the channels C21 and C41 providing fluid communication between the second piston chamber C2 and the fourth piston chamber C4, respectively, with the bypass channel outlet 91 shown in FIGS. 4a-4c.

(116) FIG. 4m is a cross-sectional view through J-J of FIG. 4b and shows i.a. the conduit 53 providing fluid communication between the second leakage channel 54 and the first leakage channel 52. The conduit 53 is provided in a portion of the piston housing PH. It should be noted that the conduit 53 is provided with a restriction at the merging point at the vena contracta portion of the first leakage channel 52, i.e. at the tee T.

(117) FIG. 4n is a cross-sectional view through K-K of FIG. 4b and shows i.a. the rods R for connecting the second piston P2 with the bypass channel closing element 21, extending through the piston housing PH.

(118) FIG. 4o is a cross-sectional view through L-L of FIG. 4b and shows i.a. the bypass channel closing element 21 of the piston arrangement 20. The bypass channel closing element 21 is provided with a protrusion 21′ for blocking the bypass channel outlet 312. The bypass channel closing element 21 is in the embodiment shown arranged substantially within an upper half of the valve 1. It should be clear that there is no fluid communication between the upper half and a lower half of the valve 1 at L-L.

(119) FIG. 4p is a cross-sectional view through M-M of FIG. 4b and shows the bypass channel outlet 312 forming an aperture through the first valve seat 40. The first valve seat 40 is in the form of an annular wall 40 protruding from an inner surface of the housing H. The oblong slit 314 mentioned above forms an opening through the first valve seat 40. Said opening provides a fluid path for fluid flowing from the primary flow channel 3 when the piston arrangement 20 is in its inactive position wherein the bypass channel outlet 312 is closed by the protrusion 21′ of the bypass channel closing element 21. In a lower portion of the first valve seat element 40 there is provided a pressure communication channel 46 for providing pressure communication between the primary flow channel 3 and an annular conduit chamber 48 (see FIG. 4a) defined by the barrel P, the housing H, the second valve seat element 40′, the primary channel closing element 23 and a portion of the first valve seat element 40. The purpose of the pressure communication channel 46 is to provide an added closing force to the piston arrangement 20 when the valve 1 is closed, i.e. when the piston arrangement 20 is in its active position.

(120) FIG. 4q is a cross-sectional view through N-N of FIG. 4b and shows i.a. the annular cavity 42 formed in the primary channel closing element 23. In a lower portion, the annular cavity 42 is provided with the piston conduit 240 for providing fluid communication with the aperture 35 in the barrel P (see for example FIGS. 4a-4c).

(121) FIGS. 5a-5c shows in a larger scale various views of one embodiment of the inlet tube 57. The inlet tube is provided with two inlets 59, 59′ arranged, in a position of use, at a top portion thereof, and an outlet 57′ at a bottom portion thereof. The outlet 57′ is configured for connection with the primary inlet 5 of the primary flow channel 3 as shown for example in FIGS. 4a-4c. FIG. 5a is seen in an upstream direction, i.e. from left to right through cross-section B-B in FIG. 4b. A top view of the inlet tube 57 is shown in FIG. 5b, while FIG. 5c is a side view of the inlet tube 57.

(122) FIG. 6 is an axial cross-sectional view through R-R of FIG. 4e (and FIG. 4f) and shows i.a. the third piston chamber channel C110 providing fluid communication between the secondary flow channel second inlet 110 and the third piston chamber C3. Further, FIG. 6 shows the conduit 131 for providing fluid communication between the third piston chamber C3 and the inlet or pilot hole 130 in the primary flow channel 3. As mentioned above, the inlet 130 is preferably independent of the pilot hole 13 providing fluid communication between the first piston chamber C1 and the primary flow channel 3.

(123) FIG. 7 is an axial cross-sectional view through S-S of FIG. 4e and shows i.a. the bypass channel first inlet 31 and the bypass channel second inlet 310 being in fluid communication with the fourth piston chamber C4 by means of the second piston chamber channel C31 and the fourth piston chamber channel C310, respectively. By means of the apertures A31 and A310, the second piston chamber channel C31 and the fourth piston chamber channel C310 are also in fluid communication with the second piston chamber C2.

(124) FIG. 8 is an axial cross-sectional view through T-T of FIG. 4e and shows i.a. the rods R connecting the first piston P1 to the second piston P2, the second piston P2 to the bypass channel closing element 21, and the bypass channel closing element 21 to the primary channel closing element 23. Thus, the piston rods R provide a connection for all parts of the piston arrangement 20.

(125) From the discussion above it will be understood that the valve 1 shown in FIGS. 4a to 8 is configured also for being capable of reopening after being closed, i.e. with the piston arrangement 20 being in its active position. Such a reopening is of particular interest when the valve 1 is used in an oil producing well wherein undesired fluids in the form of gas and water are likely to occur throughout the lifetime of the well. The capability of reopening is due to the leakage channels 52 and 54 that provide a “draining” of the valve 1 when in an active or closed position. For example, if the valve 1 has been closed due to gas above a predetermined level, that has been flowing through the valve 1 (as shown in FIG. 4c) and oil is coming back, the gas is drained or urged out of the valve 1 at least via the first leakage channel 52, the bypass channel outlet 312, the annular chamber 42, the piston conduit 240 and the aperture 35 in the barrel P. Similarly, if the valve 1 has been closed due to water above a predetermined level has been flowing through the valve 1 (as shown in FIG. 4c) and oil is coming back, the water is drained or urged out of the valve 1 at least via the second leakage channel 54, the bypass channel outlet 312, the annular chamber 42, the piston conduit 240 and the aperture 35 in the barrel P.

(126) From the above discussion it will also be understood that the hydraulic pressure within the four piston chambers C1, C2, C3 and C4 is high, i.e. at substantially the same pressure as the fluid upstream of the barrier 7, when the piston arrangement 20 of the valve 1 is in its inactive or active position. The piston arrangement 20 moves from its inactive position to its active position and closes the valve 1 when the hydraulic pressure within the second and fourth piston chambers C2, C4 exceeds the hydraulic pressure within one of the first and third piston chambers C1, C3. Such a situation will occur if one of the two closing elements 30, 30′ moves within their respective path 32, 32′ from the bypass channel first inlet 31 or bypass flow channel second inlet 310, to the secondary flow channel first inlet 11 (which is the situation when water above a predetermined level flows into the valve 1) or to the secondary flow channel second inlet 310 (which is the situation when gas above a predetermined level flows into the valve 1).

(127) The valve 1 discussed above is configured for re-opening once the fraction of undesired fluids, such as gas and water, drops below a predetermined limit, even if there is a pressure difference across the valve.

(128) From the above it should be clear that when the valve 1 is closed, both the first leakage channel 52 and the second leakage channel 54 provide fluid communication between the fluid upstream of the barrier 7, i.e. the inlet 5 of the valve 1, and the annular cavity 42.

(129) In order to avoid a too high leakage flow rate through a closed valve 1, the two leakage channels 52, 54 may typically be merged into one common channel, as shown, before entering the low-pressure cavity 42 from the bypass channel outlet 312. A diameter of the merged leakage channel will determine the total leakage flow rate, whereas the diameter ratio of the first leakage channel 52, the second leakage channel 54 and other channels entering the tee T will determine the water or gas fraction below which the valve 1 re-opens. The valve 1 will normally be designed to re-open at a water or gas fraction significantly lower than the water or gas fraction where it closes in order to prevent a situation where the valve 1 continuously toggles between closed and open position. By significantly lower is meant for example 5%.

(130) The embodiment of the present invention discussed above is an example of a design suitable for achieving the desired properties of the valve 1. However, numerous alternative designs are possible.

(131) From the disclosure herein, a person skilled in the art will appreciate that the valve 1 according to the present invention is an AICD (Autonomous Inflow Control Device) that operates independently of fluid viscosity, flow rate and Reynolds number, and that is also capable of reliably blocking or restricting two undesired fluids having different density, for all flow rates once the volume fraction of the unwanted fluid exceeds a pre-defined limit. The valve 1 has very few movable parts and operates in response to phase split, i.e. volume fractions of desired and undesired fluids flowing through the valve 1.

(132) Embodiments of the valve 1 according to the invention provides reliable re-opening mechanisms.

(133) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.