Fluid flow control system employing gravity driven float and valve

Abstract

The present disclosure provides a fluid flow control system and a well system. In one aspect, the fluid flow control system includes a valve having a fluid inlet operable to receive a fluid, a control inlet operable to receive a control fluid, and a fluid outlet operable to transmit the fluid to a tubing, the valve configured to open or close the fluid outlet based on the control fluid. The fluid flow control system according to this aspect further includes a density control valve having an inlet conduit operable to receive the fluid and an outlet conduit coupled to the control inlet of the valve, the density control valve operable to send the control fluid to the valve to open or close the fluid outlet based on a density of the fluid.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Application Serial No. 17 / 237,257, filed April 22, 2021, entitled “FLUID FLOW CONTROL SYSTEM EMPLOYING GRAVITY DRIVEN FLOATS AND A VALVE,” which is commonly assigned with the present application and incorporated by reference herein in its entirety. BACKGROUND

[0003] In hydrocarbon production wells, it can be beneficial to regulate the flow of formation fluids from a subterranean formation into a wellbore that penetrates the subterranean formation. Such regulation can be required for a variety of reasons or purposes, including, for example, to prevent water and / or gas coning, to minimize water and / or gas production, to minimize sand production, to maximize oil production, to balance production from various subterranean zones, and to equalize pressure between various subterranean zones, among others.

[0004] Many devices and valves are available to regulate the flow of formation fluids. Some of these devices can be indiscriminate with respect to different types of formation fluids and can simply act as a “gatekeeper” for regulating entry into the interior of a wellbore tubular, such as a production string. Such gatekeeper devices can be simple on / off valves, or they can be metered to regulate fluid flow over a continuous range of flow rates. Other types of devices for regulating the flow of formation fluids can implement at least some degree of discrimination between different types of formation fluids. Such devices can include, for example, tubular flow restrictors, nozzle-type flow restrictors, autonomous inflow control devices, non-autonomous inflow control devices, ports, tortuous paths, and combinations thereof. SUMMARY

[0005] Reference will now be made to the following descriptions in conjunction with the accompanying drawings, in which:

[0006] Figure 1 A schematic view of a well system designed, manufactured, and operated in accordance with one or more embodiments of the present disclosure is shown;

[0007] Figure 2 A very basic configuration of a density control valve designed, manufactured, and operated in accordance with one embodiment of the present disclosure is shown;

[0008] Figure 3 One embodiment of a density control valve employing a larger density-dependent float (at least as compared to the smaller outlet) is shown;

[0009] Figure 4 A density control valve designed, manufactured, and operated in accordance with an alternative embodiment of the present disclosure is shown;

[0010] Figures 5A-5D An embodiment of a density control valve is shown in a cross-section of a well completion string. Figure 4

[0011] Figure 6A An embodiment of a well completion string is shown that can include a density control valve similar to one or more of the density control valves discussed herein.

[0012] Figure 6B A typical placement of a housing of a density control valve and a density dependent float in a cross-section of a well completion string is shown.

[0013] Figure 6C A typical placement of a density control valve in a vertical or deviated well is shown.

[0014] Figure 7 An embodiment of a density control system that can be used to assist in solving the directional problems discussed herein is shown.

[0015] Figure 8 An expanded view (360°) of an apparatus is shown that includes four directional dependent inflow control devices distributed equidistantly around the periphery of the exterior of a central pipe.

[0016] Figure 9 A fluid flow control system designed, manufactured, and operated in accordance with one or more embodiments of the present disclosure is shown.

[0017] Figures 10A-10D An alternative embodiment of a density control valve is shown in a cross-section of a well completion string.

[0018] Figure 11 A fluid flow control system designed, manufactured, and operated in accordance with one or more alternative embodiments of the present disclosure is shown; and

[0019] Figures 12A-12D An alternative embodiment of a density control valve is shown in a cross-section of a well completion string. DETAILED DESCRIPTION

[0020] In the following drawings and description, like numbers represent like elements throughout the several views, consistent with those used in the art. The drawings presented are not necessarily to scale. Certain features of the present disclosure can be shown exaggerated in scale or in somewhat schematic form and some details can, therefore, not be depicted to the extent that they would appear in a real-life depiction of the present disclosure. The present disclosure can be embodied in different forms.

[0021] ​The detailed description and specific examples shown in the drawings should not be construed as limiting the present disclosure, which is to be considered as limited only by the spirit and scope of the principles hereof. It should be appreciated that the various teachings herein can be employed alone or in any suitable combination to yield yet further variations that are deemed to fall within the scope of the present disclosure.

[0022] Unless otherwise indicated, the use of terms such as "connected," "engaged," "coupled," "attached," or any other similar term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and can include indirect interaction where described. Unless otherwise indicated, the use of terms such as "up," "upper," "upwardly," "uphole," "upstream," or other like terms should be construed to mean generally in a direction away from the bottom, terminal end of a well, regardless of wellbore orientation; likewise, the use of terms such as "down," "lower," "downwardly," "downhole," or other like terms should be construed to mean generally in a direction toward the bottom, terminal end of a well, regardless of wellbore orientation. The use of any one or more of the above terms does not imply a position along a perfectly vertical axis. Unless otherwise indicated, the use of the term "subterranean formation" should be construed to encompass both areas beneath exposed land and areas beneath land covered by bodies of water such as oceans or freshwater bodies.

[0023] Figure 1 A schematic view of a well system 100 designed, manufactured, and operated in accordance with one or more embodiments of the present disclosure is shown. The well system 100 can include a wellbore 105 that includes a generally vertical open hole section 110 that can transition into a generally horizontal open hole section 115 that extends through a subterranean formation 120. In some examples, the vertical section 110 can extend downward from a portion of the wellbore 105 in which a casing string 125 is cemented therein. A tubular string, such as a tubing string 130 (e.g., production tubing), can be installed in or otherwise extend into the wellbore 105.

[0024] In the illustrated embodiment, one or more production packers 135, oil well screens 140, and fluid flow control systems 145 can be interconnected along the tubing string 130. In most systems, there are at least two sets of production packers 135, oil well screens 140, and fluid flow control systems 145 interconnected along the tubing string 130. The production packers 135 can be configured to seal an annulus 150 defined between the tubing string 130 and a wall of the wellbore 105. As a result, in some embodiments, fluid can be produced from multiple zones of the surrounding subterranean formation 120 via isolated sections of the annulus 150 between adjacent pairs of production packers 135. The oil well screens 140 can be configured to filter fluid flowing from the annulus 150 into the tubing string 130.

[0025] In one or more embodiments, each of the one or more fluid flow control systems 145 can include a valve having a fluid inlet (e.g., a production fluid inlet) operable to receive fluid from the subterranean formation 120, a control inlet operable to receive control fluid from the density control valve, and a fluid outlet (e.g., a production fluid outlet) operable to communicate fluid from the subterranean formation 120 to the tubing 130. In at least one embodiment, the density control valve provides a control signal to the valve based on the density of the fluid flowing therethrough. In at least one embodiment, the valve communicates fluid from the subterranean formation 120 to the tubing 130 based on receiving or not receiving the control signal. For example, if the density control valve senses mud or oil, it will instruct and / or allow the valve to communicate fluid. Conversely, if the density control valve senses gas or water, it will instruct and / or allow the valve to prevent fluid from being communicated from the subterranean formation 120 to the tubing 130. Details of the valve, the density control valve, and their combination are discussed in detail below.

[0026] Figure 2 A very basic configuration of a density control valve 200 designed, manufactured, and operated in accordance with one embodiment of the present disclosure is shown. In at least one embodiment, the density control valve 200 includes a housing 210 provided with an inlet 220 and an outlet 225, which in one embodiment is disposed in a bottom portion of the housing 210. In certain embodiments, the housing 210 has an oblong form.

[0027] A density dependent float 230, which in one embodiment is a ball, can be disposed within the housing 210. The density dependent float 230 has a density adapted to the density of the relevant fluid to be controlled. The fluid to be controlled can be, but is not limited to, drilling mud, oil, gas, and water.

[0028] The density dependent float 230 is sized and formed to be able to substantially obstruct the outlet 225 when abutting the outlet 225. Again, in certain embodiments, the density dependent float 230 is a ball that sits within the outlet 225. In other embodiments, the density dependent float 230 is much larger than the outlet 225. For example, the cross-sectional area of the density dependent float 230 (e.g., the area of the density dependent float 230 proximate the outlet 225) can be at least 50% larger than the area of the outlet 225. In yet another embodiment, the cross-sectional area of the density dependent float 230 can be at least 200% larger than the area of the outlet 225, and in certain other embodiments at least 500%, 1000%, or even more. The increased size of the density dependent float 230 compared to the outlet 225 helps to ensure that any buoyancy of the density dependent float 230 overcomes any suction pressure at the outlet 225. Briefly turning to Figure 3 , an embodiment of a density control valve 300 employing a larger density dependent float 330 (at least compared to the smaller outlet 325) is shown.

[0029] Return to Figure 2 In at least one embodiment, the housing 210 is further provided with a leakage path 240 for allowing fluid to continuously leak out of the housing 210, even if the outlet 225 is blocked by the density-dependent float 230. Figure 2 In the diagram, leakage path 240 is intended to illustrate one or more orifices in housing 210. Therefore, in the event of a change in the fluid inflow into density control valve 200, the first fluid within housing 210 can be displaced by a second fluid. When studying... Figure 5C The importance of leakage path 240 will then be understood, where the equipment blocks the flow of gas through density control valve 200. Without leakage path 240 in the intermediate housing 210", if the fluid inflow changes, any gas trapped in housing 210" cannot be displaced by another fluid of higher density. Therefore, the density-dependent float 230" within housing 210" will still block outlet 225, and thus still block fluid flow through density control valve 200.

[0030] Figure 2 The density control valve 200 is further provided with an inlet conduit 250 and an outlet conduit 260. The inlet conduit 250 is typically connected to the oil pipe (e.g., Figure 1 The annulus outside the oil pipe 130 is directly connected. The annulus is connected to the underground strata (e.g., Figure 1 The fluid from the underground formation 120 may or may not be filtered, for example, by a screen pipe before entering the inlet conduit 250. The outlet conduit 260 connects to the tubing (e.g., Figure 1 The oil pipe (130) is in fluid connection.

[0031] Turn Figure 4 This illustrates a density control valve 400 designed, manufactured, and operated according to an alternative embodiment of the present disclosure. The density control valve 400 is similar in many respects to... Figure 2 Density control valve 200. Therefore, similar reference numerals have been used to indicate similar (if not identical) features. Compared to density control valve 200, density control valve 400 includes a plurality of (e.g., three in the illustrated embodiment) housings 210, inlet 220, outlet 225, and density-dependent floats 230 arranged in series. Figure 4 In the middle, from left to right, the plurality of housings 210 will be indicated by reference numerals 210', 210”, 210”', the plurality of inlets 220 will be indicated by reference numerals 220', 220”, 220”', the plurality of outlets 225 will be indicated by reference numerals 225', 225”, 225”', and the density-dependent float 230 will be indicated by reference numerals 230', 230”, 230”'.

[0032] In Figure 4 , the density dependent float 230' has a grid-like surface pattern showing a series of ridges and valleys providing an uneven surface. The purpose of the uneven surface is to provide a leakage path allowing a small amount of leakage or seepage of fluid between the perimeter of the outlet 225' and the density dependent float when the density dependent float 230' abuts the outlet 225'. Note that the leakage path in the left housing 210' is provided by the uneven surface of the density dependent float 230'. In contrast, the housings 210", 210"' include leakage paths 240", 240"' respectively. As an alternative or in addition to the uneven surface of the density dependent float 230', the leakage path can be provided by means of the outlet 225", 225"' having a perimeter that is inconsistent with the surface of the density dependent float 230", 230"' having a substantially smooth surface.

[0033] The housing 210' is provided with an inlet 220' that is in fluid communication with the inlet conduit 250 of the density control valve 400. The housing 210' is further provided with a bottom outlet 225' and a top outlet 225' arranged in the bottom portion and the top portion respectively. The bottom outlet 225' is in fluid communication with the outlet conduit 260 via the bypass channel 470. The top outlet 225' is in fluid communication with the inlet 220" of the housing 210".

[0034] The housing 210" is provided with a bottom outlet 225" that is in fluid communication with the inlet 220"' of the housing 210"'. The housing 210"' is provided with a top outlet 225"' that is in fluid communication with the outlet conduit 260 of the density control valve 400.

[0035] As Figure 4 shown, the density control valve 400 is provided with a housing 480 and compartment elements 485, 490. The housing 480 and the compartment elements 485, 490 are configured to provide the desired flow communication between the interior and the exterior of the density control valve 400.

[0036] It is emphasized that Figure 4 the configuration shown is only one example of a configuration of the density control valve 400, and that different arrangements, sequences of the housings 210', 210", 210"' and / or the density dependent floats 230', 230", 230"' or other configuration variations of the density control valve 400 can be provided by the present disclosure.

[0037] Turning to Figures 5A-5D , density control valves 400 at different stages of the well life of a production oil well are shown. Figure 4 Please note that in Figures 5A-5D , the density control valve 400 is provided with a density dependent float 230' having a grid-like surface pattern showing a series of ridges and valleys providing an uneven surface. The purpose of the uneven surface is to provide a leakage path allowing a small amount of leakage or seepage of fluid between the perimeter of the outlet 225' and the density dependent float when the density dependent float 230' abuts the outlet 225'. Note that the leakage path in the left housing 210' is provided by the uneven surface of the density dependent float 230'. In contrast, the housings 210", 210"' include leakage paths 240", 240"' respectively. As an alternative or in addition to the uneven surface of the density dependent float 230', the leakage path can be provided by means of the outlet 225", 225"' having a perimeter that is inconsistent with the surface of the density dependent float 230", 230"' having a substantially smooth surface. Figure 4The uneven surface density-dependent float 230' shown is replaced by a density-dependent float 530' having a surface similar to that of the density-dependent floats 230”, 230”', and the housing 210' is provided with a leakage path 540'.

[0038] The direction of fluid inflow and outflow from the density control valve 400 is indicated by a solid arrow, or by a dashed arrow indicating a lack of flow. Figures 5A-5D In this embodiment, the density-dependent float 530' has a density higher than that of oil, water, and gas, but lower than that of mud. The mud can be, for example, drilling mud or well-building mud. The density-dependent float 230"' has a density higher than that of gas, but lower than that of mud, oil, and water. The density-dependent float 230"' has a density higher than that of gas and oil, but lower than that of mud and water. For the purposes of this discussion, a specific specific gravity of water can be between 0.95 and 1.05, and a specific specific gravity of mud can be between 1.06 and 2. In at least one embodiment, water can have a specific specific gravity between 1 and 1.04, and mud can have a specific specific gravity between 1.06 and 1.10. In at least one other embodiment, water can have a specific specific gravity of 1.02, and mud can have a specific specific gravity of 1.06.

[0039] exist Figure 5A In the middle, the mud will flow through the density control valve 400, from the inlet conduit 250 to the outlet conduit 260. Figure 5B In the middle, the oil will flow through the density control valve 400, from the inlet conduit 250 to the outlet conduit 260. Figure 5C and 5D In this process, the flow of gas and water will be substantially restricted through density control valve 400. The only passage for gas and water through density control valve 400 is via leakage paths 540', 240", 240"'. This very limited flow is indicated by small arrows in inlet conduit 250 and outlet conduit 260.

[0040] The aforementioned reason can be explained as follows. After entering the inlet conduit 250 of the density control valve 400, the fluid flow enters the left housing 210', which is designed to bypass the well-building fluid directly to the outlet conduit 260 via the bypass channel 470. Since the density-dependent float 230' has a density higher than that of formation water (the second densest fluid) and lower than that of the well-building fluid (the densest fluid), the dense well-building fluid exists in all spaces of the density control valve 400 before well start-up / cleaning. This means that the density-dependent floats 530', 230", and 230"' will initially be positioned at the top portions of the housings 210', 210", and 210"', respectively, due to their buoyancy relative to the dense well-building fluid.

[0041] During initial well start-up / clean-up, the well will thus start flowing construction fluid through the inlet conduit 250 and the bypass channel 470, to the outlet conduit 260, as shown. Figure 5A

[0042] Initially, the flow will essentially consist of construction fluid. After some time, the construction fluid will be purged, and reservoir fluid will start flowing out. In the configuration shown, the density control valve 400 is designed to allow oil through, and restrict gas and water from the reservoir. Assuming that the reservoir fluid produced after the construction fluid is purged is oil, the density of the density dependent float 530' is such that it will lose buoyancy in the reservoir fluid. Figures 5A-5D

[0043] However, the density dependent float 530' will keep its position due to the suction in the top outlet 225' of the housing 210'. The leakage paths 540', 240", 240"' and the housing 480 will help with the subsequent total fluid displacement in the housings 210", 210"'.

[0044] After essentially all construction fluid is displaced by oil, the density dependent float 230" will keep its position at the top of the housing 210" due to its density being between the density of gas and oil. The density dependent float 230"' will sink to a position at the bottom of the housing 210"' due to its density being higher than the density of oil and lower than the density of water.

[0045] The density dependent float 530' will keep its position due to the suction in the top outlet 225' of the housing 210', as described above. This means that neither the housing 210" nor the housing 210"' is supplied with fluid from the outlet of the housing 210'. Therefore, fluid flows through the density control valve 400 via the bypass channel 470. This flow pattern will continue until the well is first shut-in for production, typically as part of the start-up procedure when the so-called well clean-up is satisfactory.

[0046] After the first planned production shut-in of the well, the density dependent floats 530', 230", 230"' will find their correct positions for the current reservoir fluid, as shown. Figure 5B

[0047] ​​​Assuming oil flows from the reservoir, since its density is between the density of water and the density of the well completion fluid, density dependent float 530' will sink and block the bottom outlet 225'. Flow will then be forced to pass through the top outlet 225' and into housing 210". There, density dependent float 230" will be buoyant due to its density being between the density of oil and the density of gas, and the fluid will pass unrestricted through housing 210" and out outlet 225", into housing 210"' via compartment element 485. In housing 210"' density dependent float 230"' will be positioned at the bottom of housing 210"' due to its density being higher than the density of oil and lower than the density of water, and the fluid will pass unrestricted through housing 210"' and to outlet conduit 260 via compartment element 490.

[0048] At the later stages of the well life, if gas coning or any other phenomenon introduces free gas in the fluid flow from the reservoir through density control valve 400, density dependent float 230" will lose its buoyancy and fall to block the main flow path through outlet 225" of housing 210", as Figure 5C shown.

[0049] If gas-oil contact is subsequently pulled back and the formation around density control valve 400 is refilled with oil, the old fluid (gas) in density control valve 400 will be replaced with the new fluid (oil) by the continuous leakage flow through leakage paths 540', 240", 240"'. Without leakage paths 540', 240", 240" or any other leakage means, the high or low density fluid that activated density dependent float 530', 230", 230"' can not be replaced and the re-opening will be disabled. Therefore, leakage paths 540', 240", 240" will prevent the fluid from being "trapped inside" density control valve 400, and density control valve 400 will also be autonomous for this case.

[0050] Leakage paths 540', 240", 240" are positioned or arranged in housings 210', 210", 210"' in such a way that there is essentially no area where any type of fluid is trapped when the new fluid surrounds inlet conduit 250 of density control valve 400.

[0051] If water is introduced through water coning or other phenomena, density dependent float 230"' will become buoyant and rise to block the main flow through top outlet 225"' of housing 210"' and thus through density control valve 400 due to its density being lower than the density of water. This is Figure 5D shown in

[0052] Turning back Figure 6AAn embodiment of a completion string 600 is shown, which may include one or more density control valves 605 similar to those described above. In the illustrated embodiment, the density control valve 605 is positioned between the center tube 680 and the filter screen 690. The density control valve 605 may form part of a so-called tube rack, which typically has a length of approximately 12 meters. However, the density control valve 605 may also be arranged in a separate tube unit with a typical length of only 40 to 50 centimeters. Such a unit may be configured to be inserted between two consecutive tube racks.

[0053] Figure 6B The typical placement of the housing 610 of the density control valve 605 and the density-dependent float 630 in the cross-section of the completion string 600 is shown. Figure 6B The placement shown is precisely relative to the gravity vector g, but rotation around the axis of the central tube 620 by a certain angle is acceptable. Because the density control valve 605 is orientation-dependent, proper orientation of the density control valve 605 around the axis of the central tube 680 is required in the horizontal or near-horizontal sections of the well. In the vertical or inclined sections of the well, orientation around the axis of the central tube 680 may not be necessary. The typical placement of the density control valve 605 in a vertical or inclined well is generally... Figure 6C As shown in the image.

[0054] Ensure density control valve 605 (or as Figure 4 The correct orientation of the density control valve 400 in the horizontal section can be addressed during well completion using appropriate tools. One known way to ensure correct orientation is by allowing specific sections of each completion section (e.g., where the equipment is installed) to rotate freely. Further, for this embodiment, specially designed wireline tools can be used to position and lock each section to its correct orientation before well start-up. An alternative to forced orientation via wireline tools is to design equipment with a large cross-section, allowing the equipment to automatically rotate to the correct orientation before initial well start-up. To lock the equipment in its correct position, a hydrocarbon expansion package can be mounted on the rotating section to expand and lock position against the formation wall.

[0055] Turning Figure 7 An embodiment of a density control system 700 that can be used to assist in solving the aforementioned orientation problem is shown. The density control system 700 is similar in many respects to the above-described density control system. Figure 4 The density control valve 400 is discussed. Therefore, similar reference numerals have been used to indicate similar (if not identical) features. Figure 4 Conversely, the density control system 700 includes a directional-dependent inflow control device 705. For example, in Figure 7In the middle, the inlet conduit 250 of the density control valve 400 is in fluid communication with the outlet 760 of the directional dependent inflow control device 705. The purpose of the directional dependent inflow control device 705 is to control the fluid flow from the outside to the inside of the tubing in a deviated well or a horizontal well. The directional dependent inflow control device 705 will hereinafter also be denoted as an autonomous directional interpretation device. The directional dependent inflow control device 705 is an alternative to the forced directional and self- directional as described above.

[0056] Figure 7 The directional dependent inflow control device 705 in the middle comprises a first directional housing 710' having a longitudinal axis and provided with a first directional inlet 720' and a first directional outlet 725', a second directional housing 710" having a longitudinal axis and a second directional inlet 720" and a second directional outlet 725". The directional outlets 725', 725" are arranged in end portions of the housings 710', 710", respectively. According to the first aspect of the present invention, the first directional outlet 725' is in fluid communication with the second directional inlet 720" and the second directional outlet 725" is arranged in fluid communication with the inlet conduit 250 of the density control valve 400.

[0057] A blocking member 730', 730" is arranged within each of the housings 710', 710", respectively. The blocking members 730', 730" are configured to allow blocking of the directional outlets 725', 725" to shut off the fluid flow through the directional dependent inflow control device 705. The density of the blocking members 730', 730" is higher than the density of the well fluid having the highest potential density during the service life of the well, or lower than the density of the well fluid having the lowest density during the service life of the well. Steel is an example of a suitable material for use as a high density blocking member.

[0058] The first directional housing 710' and the second directional housing 710" are arranged mutually distanced in the tubing or at the periphery of the tubing such that the angle of inclination of the first directional housing 710' is different from the angle of inclination of the second directional housing 710". Thus, the flow through the directional dependent inflow control device 705 can be blocked by the blocking member 730' in the first directional housing 710' or by the blocking member 730" in the second directional housing 710".

[0059] When rotated more than a predetermined angle around the central tubing axis, the blocking member 730' will abut and block the directional outlet 725' of the first directional housing 710' and thus prevent fluid flow through the directional dependent inflow control device 705 and into the subsequent density control valve 400.

[0060] When rotated below the predetermined angle around the central tube axis, the blocking member 730' will be positioned in the lower part of the directional housing 710'. Fluid can then flow out through the outlet of the first directional housing 710'. However, because the directional dependent inflow control device 705 is rotated below the predetermined angle, the blocking member 730" will abut and block the directional outlet 725" of the second directional housing 710", and thus prevent fluid flow through the directional dependent inflow control device 705 and into the subsequent density control valve 400.

[0061] When the directional dependent inflow control device 705 is arranged at the predetermined angle, which can be a span of angles, both blocking members 730' and 730" will be positioned away from the directional outlets 725', 725" and fluid can flow through the directional dependent inflow control device 705 and into the density control valve 400.

[0062] By arranging a plurality of directional dependent inflow control devices 705, e.g. equidistantly around the periphery of the central tube, independently of each other, e.g. by means of a common shaft, at least one of the directional dependent inflow control devices 705 should be within the desired predetermined angle, and thus enable fluid flow through the directional dependent inflow control device 705 and ensure correct functioning of the density control valve 400 according to the first aspect of the present disclosure. In at least one embodiment, this happens without the risk of unwanted fluid bypassing the density dependent float 230', 230", 230"'.

[0063] Figure 8 An unfolded view (360°) of an apparatus is shown, comprising four directional dependent inflow control devices 705 distributed equidistantly around the periphery of the outside of a central tube (not shown). In Figure 8 The reference indications x and x' are connected to each other, and the reference indications y and y' are connected to each other.

[0064] Each of the four directional dependent inflow control devices 705 is in fluid communication with a corresponding density control valve 400, e.g. as disclosed in the example in Figure 7 The orientation of each of the four directional dependent inflow control devices 705 is indicated by a g vector wherein the indication + should be understood as being in the direction into the drawing, the downward arrow being in a vertically downward direction, ● the indication - should be understood as being in the direction out of the drawing, and the upward arrow being in a vertically upward direction.

[0065] Figure 8The density control valve system 800 in the illustrated embodiment assumes placement in an oil well in a section of the well that is producing oil. To facilitate Figure 8 understanding, each pair of blocking members 730', 730" in each of the directional dependent inflow control devices 705 is indicated by dissimilar hatching. However, it should be understood that all eight blocking members 730', 730" can be identical, and the dissimilar hatching is merely used to identify the paired blocking members 730', 730" within each of the four directional dependent inflow control devices 705.

[0066] As Figure 8 illustrated, only one of the four directional dependent inflow control devices 705 has an orientation in which both blocking members 730', 730" have a position in the bottom portion of their respective housings 710', 710", and thus allow fluid flow through the directional dependent inflow control device 705 and into the subsequent density control valve 400. The flow is indicated by the arrow 805. Note that the density control valve 400 open to fluid flow therethrough corresponds to the device illustrated in Figure 5B .

[0067] For the other three directional dependent inflow control devices 705, at least one of the blocking members 730', 730" blocks the directional outlet 725', 725" of the respective housing 710', 710", and thus prevents fluid flow through the directional dependent inflow control device 705 and into the subsequent density control valve 400.

[0068] As noted above, Figure 8 the blocking members 730', 730" in each of the four directional dependent inflow control devices 705 are generally of a density of steel, and will find their proper position regardless of the type of fluid around them.

[0069] If lower density blocking members 730', 730" (e.g., having a density lower than that of steel) are used in place of the higher density blocking members 730', 730" illustrated in the figures, it will be understood by those skilled in the art that the outlets from 710', 710" must be placed in opposite portions of the directional dependent inflow control device 705 so that when the blocking members 730', 730" "float", the outlet of each 710', 710" is blocked.

[0070] To ensure reliable operation of the directional dependent inflow control device 705, the housings 710', 710" can be provided with a substantially flat portion or floor. If no flat portion or floor is used in the housings 710', 710", the placement of these housings 710', 710" should take into account that the completion string is normally rotated during installation. If low density barrier members 730', 730" (not shown) are used, the flat portion should be arranged in the top portion or "top floor" of the housings 710', 710".

[0071] The above discussion is an example of one way of using the density control valve 400 and the density control valve systems 700, 800 in accordance with the present disclosure. However, the density control valve 400 and the density control valve systems 700, 800 can be customized for specific purposes.

[0072] The density control valve 400 and the density control valve systems 700, 800 can be optimized for so-called gas generators in order to only discriminate water in the gas / condensate generator. This can be achieved by simply removing the flow control device or the density dependent float 230', or by removing the entire housing 210' so that the density control valve 400 only comprises two housings 210", 210"' instead of three housings 210', 210", 210"' as shown in Figure 4 The same configuration can be used for unsaturated oil producing wells where no gas is expected during the lifetime of the well. Similarly, Figure 4 The device in the density control valve system 800 can be designed to only discriminate gas by removing the flow control device or the density dependent float 230", or by removing the entire housing 210".

[0073] The present disclosure has recently recognized that density control valves, such as the density control valves disclosed above, can have problems when used as master control valves. In particular, when used as master control valves, the density control valves rely on the density dependent float to control the master flow from the annulus to the tubing. However, when doing so, the suction pressure from the water level drop can be too high to allow the buoyancy to control the density dependent float, and thus render the density control valve unable to fulfill their intended purpose. The present disclosure has recognized that the aforementioned problem can be solved by having the density control valve only control a small fraction of the flow, and then using this small fraction to provide control to a valve that is used to control the master flow from the annulus to the tubing. Since the pressure drop across the density dependent float is small when the flow rate is low, they do not encounter suction pressure problems, and thus work well as control valves for master valves.

[0074] Figure 9A fluid flow control system 900 designed, manufactured, and operated in accordance with one or more embodiments of the present disclosure is shown. In at least one embodiment, the fluid flow control system 900 includes a flow regulator 915 operable to receive a fluid 910 (e.g., production fluid from an annulus 905). At least in Figure 9 Embodiments, the flow regulator 915 sends a first fluid flow portion 925 (e.g., a first, larger portion) of the fluid 910 to a valve 930 and a second fluid flow portion 955 (e.g., a second, smaller portion) of the fluid 910 to a density control valve 960.

[0075] The valve 930 (which can be a pilot valve in some embodiments) can include a fluid inlet 935 operable to receive the first fluid flow portion 925, a control inlet 940 operable to receive a control fluid 965 from an outlet conduit 964 of the density control valve 960, and a fluid outlet 945 operable to selectively communicate the first fluid flow portion 925 to a tubing 970. In this embodiment, the valve 930 is thus configured to open or close the fluid outlet 945 based on the control fluid 965 received from the outlet conduit 964 of the density control valve 960.

[0076] The density control valve 960 can be similar in form and function to any of the density control valves disclosed above and thus receives the second fluid flow portion 955 via an inlet conduit 962 and selectively outputs a control fluid 965 to the valve 930 via an outlet conduit 964. In certain embodiments, the density control valve 960 is coupled with a directional dependence inflow control device, as disclosed above Figure 7 and Figure 8 in the text related above. Further, the density control valve 960 and the directional dependence inflow control device can be arranged as a density control valve system, as disclosed above Figure 8 in the text related above. Thus, the density control valve system is not only able to selectively send the control fluid 965 to the valve 930 based on the type of fluid embodied by the fluid 910 (e.g., mud, oil, gas, water), but also can account for any directional issues of the density control valve 960.

[0077] In at least one embodiment consistent with the present disclosure, the density control valve 960 includes one or more housings, one or more inlets and outlets to the housings, and an associated density dependent float contained within each of the housings. In at least one embodiment, the density control valve 960 can be similar to the density control valve 460 disclosed above Figures 5A-5DThe operation is as discussed. Therefore, when fluid 910 is mud-based, density control valve 960 will send a signal (e.g., control fluid 965) to valve 930, allowing valve 930 to deliver mud-based fluid 910 from annulus 905 to tubing 970. Similarly, when fluid 910 is oil-based, density control valve 960 will again send a signal (e.g., control fluid 965) to valve 930, allowing valve 930 to deliver oil-based fluid 910 from annulus 905 to tubing 970. However, when fluid 910 is water-based or gas-based, density control valve 960 will avoid sending a signal (e.g., control fluid 965) to valve 930, allowing valve 930 to prevent water-based or gas-based fluid 910 from traveling from annulus 905 to tubing 970.

[0078] The paragraph above has been described as causing the valve 930 to open when control fluid 965 is applied, and closing the valve 930 when no control fluid 965 is applied. In fact, the reverse is also true. For example, a fluid flow control system 900 may exist such that the valve 930 is closed when control fluid 965 is applied, and the valve 930 is not opened when no control fluid 965 is applied.

[0079] Briefly turn Figures 10A-10D This illustrates alternative embodiments of the density control valve 1000 at different stages of the well life of a producing oil well. Figures 10A-10D The density control valve 1000 is similar in many ways to Figures 5A-5D Density control valve 400. Therefore, similar reference numerals are used to indicate similar features. Density control valve 1000 differs significantly from density control valve 400 in that it does not deliver slurry or oil, but rather gas and water. Therefore, density control valve 1000 can be used in the situations discussed in the preceding paragraphs. In at least one embodiment, density control valve 1000 achieves the foregoing by removing the lower outlet 225' from housing 210', adding an upper outlet 225" to housing 210", and adding the lower outlet 225"' and removing the upper outlet 225"' from housing 210"'. This is done as follows: Figures 10A-10D As shown, density control valve 1000 operates in reverse to density control valve 400.

[0080] Figure 11A fluid flow control system 1100 designed, manufactured, and operated according to one or more alternative embodiments of the present disclosure is shown. The fluid flow control system 1100 is similar in many respects to the fluid flow control system 900. Therefore, similar reference numerals are used to describe similar features. Compared to the fluid flow control system 900, the fluid flow control system 1100 includes an alternative embodiment of a valve 1130. The valve 1130 still includes: a fluid inlet 935 operable to receive a first fluid flow portion 925, a control inlet 940 operable to receive control fluid from an outlet conduit of valve 960, and a fluid outlet 945. However, the valve 1130 is operable to allow fluid 910 to flow from the annulus 905 to the tubing 970 when no control fluid is received, and to prevent fluid 910 from flowing from the annulus 905 to the tubing 970 when control fluid is received. Those skilled in the art will understand that the density control valve 960 may need to be modified to accommodate changes in the valve 1130, including potentially altering certain inlets and outlets within the housing, and changing the density of the density-dependent floats within each housing, for example, to accommodate such changes. Furthermore, the density control valve 960 may need to be modified so that it does not distinguish between mud and oil, but treats mud and oil as a single entity. In at least one embodiment, as shown, the density control valve 960 may be configured similarly to the valve 1000 shown with respect to 10A to 10D above.

[0081] Turning Figures 12A-12D This illustrates the different stages of well life in a producing oil well. Figure 11 The fluid flow control system 1100. Figure 12A In this case, the mud will not flow from the inlet pipe 962 to the outlet pipe 964 through the density control valve 960, and therefore the valve 1130 will not be closed. Figure 12B In this case, oil will again not flow from inlet conduit 962 to outlet conduit 964 through density control valve 960, and therefore valve 1130 will not be closed. Figure 12C and Figure 12D In this process, gas and water will flow from inlet conduit 962 to outlet conduit 964 through density control valve 960, and thus close valve 1130. The foregoing is achieved using density control valve 960, which may or may not (e.g., depending on its design) send control signals to valve 1130 to open or close.

[0082] The aspects disclosed in this article include:

[0083] A. A fluid flow control system comprising: 1) a valve having a fluid inlet operable to receive a fluid, a control inlet operable to receive a control fluid, and a fluid outlet operable to communicate the fluid to a tubing, the valve configured to open or close the fluid outlet based on the control fluid; and 2) a density control valve having an inlet conduit operable to receive the fluid and an outlet conduit coupled to the control inlet of the valve, the density control valve operable to send the control fluid to the valve to open or close the fluid outlet based on a density of the fluid.

[0084] B. A well system comprising: 1) a wellbore; 2) a tubing positioned within the wellbore forming an annulus with the wellbore; 3) a fluid flow control system positioned at least partially within the annulus, the fluid flow control system comprising: a) a valve having a fluid inlet operable to receive a fluid, a control inlet operable to receive a control fluid, and a fluid outlet operable to communicate the fluid to the tubing, the valve configured to open or close the fluid outlet based on the control fluid; and b) a density control valve having an inlet conduit operable to receive the fluid and an outlet conduit coupled to the control inlet of the valve, the density control valve operable to send the control fluid to the valve to open or close the fluid outlet based on a density of the fluid.

[0085] Aspects A and B can have one or more of the following combinations of additional elements: Element 1 : wherein the density control valve comprises a housing comprising an inlet and an outlet, and a density dependent float positioned within the housing, the density dependent float configured to expose or close the outlet based on a density of fluid therein. Element 2: wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises a second housing comprising a second inlet and a second outlet. Element 3: wherein the first density dependent float has a density higher than a gas but lower than oil and water, and the second density dependent float has a density higher than a gas and oil but lower than water. Element 4: wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises: a second housing comprising a second inlet and a second outlet, and a second density dependent float positioned within the second housing; and a third housing comprising a third inlet and a third outlet, and a third density dependent float positioned within the third housing. Element 5: wherein the first density dependent float has a density higher than oil, water, and gas but lower than drilling mud, the second density dependent float has a density higher than a gas but lower than mud, oil, and water, and the third density dependent float has a density higher than a gas and oil but lower than mud and water. Element 6: wherein the first density dependent float is positioned between the inlet conduit and the second density dependent float, and the third density dependent float is positioned between the second density dependent float and the outlet conduit. Element 7: wherein the density dependent float has a cross-sectional area adjacent the outlet that is at least 200% greater than an area of the outlet. Element 8: wherein the density control valve forms at least a portion of a density control valve system, and wherein the density control valve system further comprises an orientation dependent inflow control device. Element 9: wherein the orientation dependent inflow control device comprises: a first orientation housing having a first orientation inlet and an outlet, and a first blocking member positioned within the first orientation housing; and a second orientation housing having a second orientation inlet and an outlet, and a second blocking member positioned within the second orientation housing. Element 10: wherein the first orientation inlet is coupled to the fluid, the first orientation outlet is coupled to the second orientation inlet, and the second orientation outlet is coupled to the inlet conduit of the density control valve. Element 11 : wherein the first blocking member and the second blocking member have a density higher than a density of drilling mud, oil, gas, and water. Element 12: wherein the density control valve comprises a housing comprising an inlet and an outlet, and a density dependent float positioned within the housing, the density dependent float configured to expose or close the outlet based on a density of fluid therein. Element 13: wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises a second housing comprising a second inlet and a second outlet.Element 14: wherein the first density dependent float has a density higher than the gas but lower than the oil and water, and the second density dependent float has a density higher than the gas and oil but lower than the water. Element 15: wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises: a second housing comprising a second inlet and a second outlet, and a second density dependent float located within the second housing; and a third housing comprising a third inlet and a third outlet, and a third density dependent float located within the third housing. Element 16: wherein the first density dependent float has a density higher than the oil, water, and gas but lower than the drilling mud, the second density dependent float has a density higher than the gas but lower than the mud, oil, and water, and the third density dependent float has a density higher than the gas and oil but lower than the mud and water. Element 17: wherein the first density dependent float is located between the inlet conduit and the second density dependent float, and the third density dependent float is located between the second density dependent float and the outlet conduit. Element 18: wherein the density dependent float has a cross-sectional area adjacent the outlet that is at least 200% greater than an area of the outlet. Element 19: wherein the density control valve forms at least a portion of a density control valve system, and wherein the density control valve system further comprises a directional dependent inflow control device. Element 20: wherein the directional dependent inflow control device comprises: a first directional housing having a first directional inlet and an outlet, and a first blocking member located within the first directional housing; and a second directional housing having a second directional inlet and an outlet, and a second blocking member located within the second directional housing. Element 21 : wherein the first directional inlet is coupled to the fluid, the first directional outlet is coupled to the second directional inlet, and the second directional outlet is coupled to the inlet conduit of the density control valve. Element 22: wherein the first blocking member and the second blocking member have a density higher than the density of the drilling mud, oil, gas, and water.

[0086] Those skilled in the art of the field to which this application pertains will appreciate that other and further additions, deletions, substitutions and modifications can be made to the described embodiments.

Claims

1. A fluid flow control system comprising: a fluid flow control valve having a fluid inlet operable to receive a fluid, a control inlet operable to receive a control fluid, and a fluid outlet operable to transmit the fluid to a tubing, the fluid flow control valve having a member configured to open the fluid outlet based on the control fluid moving from a closed state to an open state and to close the fluid outlet based on the control fluid moving from the open state to the closed state; and a density control valve having an inlet conduit operable to receive the fluid and an outlet conduit coupled to the control inlet of the fluid flow control valve, the density control valve operable to send the control fluid to the control inlet of the fluid flow control valve to open or close the fluid outlet based on a density of the fluid, wherein the member of the fluid flow control valve is configured such that the member does not block the fluid from traveling between the inlet conduit and the outlet conduit of the density control valve as the member moves between the closed state and the open state.

2. The fluid flow control system of claim 1, wherein the density control valve comprises a housing including an inlet and an outlet, and a density dependent float within the housing, the density dependent float configured to expose or close the outlet based on a density of the fluid therein.

3. The fluid flow control system of claim 2, wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises a second housing and a second density dependent float within the second housing, the second housing including a second inlet and a second outlet.

4. The fluid flow control system of claim 3, wherein the first density dependent float has a density higher than a gas but lower than an oil and a water, and the second density dependent float has a density higher than a gas and an oil but lower than a water.

5. The fluid flow control system of claim 2, wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises: a second housing including a second inlet and a second outlet, and a second density dependent float within the second housing; and a third housing including a third inlet and a third outlet, and a third density dependent float within the third housing.

6. The fluid flow control system of claim 5, wherein the first density dependent float has a density higher than an oil, a water, and a gas but lower than a drilling mud, the second density dependent float has a density higher than a gas but lower than a mud, an oil, and a water, and the third density dependent float has a density higher than a gas and an oil but lower than a mud and a water.

7. The fluid flow control system of claim 6, wherein the first density dependent float is between the inlet conduit and the second density dependent float, and the third density dependent float is between the second density dependent float and the outlet conduit.

8. The fluid flow control system of claim 2, wherein the density dependent float has a cross-sectional area adjacent the outlet that is at least 200% greater than an area of the outlet.

9. The fluid flow control system of claim 1, wherein the density control valve forms at least a portion of a density control valve system, and wherein the density control valve system further comprises an orientation dependent inflow control device.

10. The fluid flow control system of claim 9, wherein the orientation-dependent inflow control device comprises: a first orientation housing having a first orientation inlet and a first orientation outlet, and a first blocking member positioned within the first orientation housing; and a second orientation housing having a second orientation inlet and a second orientation outlet, and a second blocking member positioned within the second orientation housing.

11. The fluid flow control system of claim 10, wherein the first orientation inlet is coupled to the fluid, the first orientation outlet is coupled to the second orientation inlet, and the second orientation outlet is coupled to the inlet conduit of the density control valve.

12. The fluid flow control system of claim 11, wherein the first blocking member and the second blocking member have a density that is higher than a density of drilling mud, oil, gas, and water.

13. A well system comprising: a wellbore; tubing positioned within the wellbore forming an annulus with the wellbore; and a fluid flow control system positioned at least partially within the annulus, the fluid flow control system comprising: a fluid flow control valve having a fluid inlet operable to receive a fluid, a control inlet operable to receive a control fluid, and a fluid outlet operable to transmit the fluid to the tubing, the fluid flow control valve having a member configured to open the fluid outlet based on the control fluid moving from a closed state to an open state and to close the fluid outlet based on the control fluid moving from the open state to the closed state; and a density control valve having an inlet conduit operable to receive the fluid and an outlet conduit coupled to the control inlet of the fluid flow control valve, the density control valve operable to send the control fluid to the control inlet of the fluid flow control valve to open or close the fluid outlet based on a density of the fluid, wherein the member of the fluid flow control valve is configured such that the member does not block the fluid from traveling between the inlet conduit and the outlet conduit of the density control valve when the member is moved between the closed state and the open state.

14. The well system of claim 13, wherein the density control valve comprises a housing including an inlet and an outlet, and a density dependent float positioned within the housing, the density dependent float configured to expose or close the outlet based on a density of the fluid therein. ​ 15. The well system of claim 14, wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises a second housing and a second density dependent float located within the second housing, the second housing comprising a second inlet and a second outlet.

16. The well system of claim 15, wherein the first density dependent float has a density higher than gas but lower than oil and water, and the second density dependent float has a density higher than gas and oil but lower than water.

17. The well system of claim 14, wherein the housing is a first housing having a first inlet and a first outlet, and the density dependent float is a first density dependent float, and wherein the density control valve further comprises: a second housing comprising a second inlet and a second outlet, and a second density dependent float located within the second housing; and a third housing comprising a third inlet and a third outlet, and a third density dependent float located within the third housing.

18. The well system of claim 17, wherein the first density dependent float has a density higher than oil, water, and gas but lower than drilling mud, the second density dependent float has a density higher than gas but lower than mud, oil, and water, and the third density dependent float has a density higher than gas and oil but lower than mud and water.

19. The well system of claim 18, wherein the first density dependent float is located between the inlet conduit and the second density dependent float, and the third density dependent float is located between the second density dependent float and the outlet conduit.

20. The well system of claim 14, wherein the density dependent float has a cross-sectional area adjacent the outlet that is at least 200% greater than an area of the outlet.

21. The well system of claim 13, wherein the density control valve forms at least a portion of a density control valve system, and wherein the density control valve system further comprises an orientation dependent inflow control device.

22. The well system of claim 21, wherein the orientation-dependent inflow control device comprises: a first orientation housing having a first orientation inlet and a first orientation outlet, and a first blocking member located within the first orientation housing; and a second orientation housing having a second orientation inlet and a second orientation outlet, and a second blocking member located within the second orientation housing.

23. The well system of claim 22, wherein the first orientation inlet is coupled to the fluid, the first orientation outlet is coupled to the second orientation inlet, and the second orientation outlet is coupled to the inlet conduit of the density control valve.

24. The well system of claim 23, wherein the first blocking member and the second blocking member have a density higher than a density of drilling mud, oil, gas, and water.

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