GB2477176A - Method of Designing a Flow Control Device using a Simulator - Google Patents

Abstract

A method of providing a flow control device 900 (138, fig. 1) for controlling flow in a wellbore (110, fig.1) includes: defining a flow rate; defining a desired relationship between a parameter of the flow control device when a selected property of the fluid changes in a first range and remains constant when the selected property is in the second range; determining using a computer and a simulation program the relationship between the performance parameter and the selected property over the first range and the second range for the defined flow rate for a geometry of a flow through area of the flow control device; comparing the determined relationship of the performance parameter with the desired relationship; altering the geometry to a new geometry when the difference between the desired performance and the determined performance is outside a desired range; repeating the process of altering the geometry and determining the performance until the difference between the desired performance and the determined performance for a geometry is acceptable; and storing the geometry on a suitable storage medium for use in manufacturing the said device. Preferably the performance parameter is one of performance coefficient as a function of Reynolds number or pressure drop across the flow through area, wherein a flow path 952a is a tortuous path such as z-shape or s-shape.

Description

METHOD OF PROVIDING A FLOW CONTROL DEVICE THAT SUBSTANTIALLY

REDUCES FLUID FLOW BETWEEN A FORMATION AND A WELLBORE WHEN A

SELECTED PROPERTY OF THE FLUID IS IN A SELECTED RANGE

The disclosure relates generally to apparatus and methods for control of fluid flow from subterranean formations into a production string in a wellbore.

Hydrocarbons such as oil and gas are recovered from a subterranean formation using a well or welibore drilled into the formation. In some cases the wellbore is completed by placing a casing along the wellbore length and perforating the casing adjacent each production zone (hydrocarbon bearing zone) to extract fluids (such as oil and gas) from such a production zone. In other cases, the wellbore may be open hole. One or more inflow control devices are placed in the wellbore to control the flow of fluids into the wellbore.

These flow control devices and production zones are generally separated from each other by installing a packer between them. Fluid from each production zone entering the wellbore is drawn into a tubing that runs to the surface. It is desirable to have a substantially even flow of fluid along the production zone. Uneven drainage may result in undesirable conditions such as invasion of a gas cone or water cone. In the instance of an oil-producing well, for example, a gas cone may cause an in-flow of gas into the welibore that could significantly reduce oil production. In like fashion, a water cone may cause an in-flow of water into the oil production flow that reduces the amount and quality of the produced oil.

A deviated or horizontal wellbore is often drilled into a production zone to extract fluid therefrom. Several inflow control devices are placed spaced apart along such a wellbore to drain formation fluid or to inject a fluid into the formation. Formation fluid often contains a layer of oil, a layer of water below the oil and a layer of gas above the oil. For production wells, the horizontal wellbore is typically placed above the water layer. The boundary layers of oil, water and gas may not be even along the entire length of the horizontal well. Also, certain properties of the formation, such as porosity and permeability, may not be the same along the well length. Therefore, fluid between the formation and the wellbore may not flow evenly through the inflow control devices. For production wellbores, it is desirable to have a relatively even flow of the production fluid into the wellbore and also to inhibit the flow of water and gas through each inflow control device. Active flow control devices have been used to control the fluid from the formation into the wellbores.

Such devices are relatively expensive and include moving parts, which require maintenance and may not be very reliable over the life of the wellbore. Passive inflow control devices ("ICDs") that are able to restrict flow of water and gas into the wellbore are therefore desirable.

The disclosure herein provides passive ICDs that in one aspect restrict the flow of fluids having undesired viscosities or densities and in another aspect maintain a substantially constant flow of fluids having desired viscosities or densities.

In one aspect, the disclosure provides a flow control device for controlling flow of a fluid between a formation and a wellbore. The flow control device in one embodiment may include an inflow region, a flow-through region and an oufflow region, wherein the flow-through region is configured to substantially increase pressure drop when viscosity or density of the fluid is in a first range and maintain a substantially constant pressure drop when the viscosity or density of the fluid is in a second. In another embodiment, the flow-through region may include a structural flow area, an inflow opening and an outflow opening, wherein the structural flow area, a fluid flow path in the structural flow area, tortuosity of the fluid flow path and size of the outflow opening are selected so that values of pressure loss coefficient ("K") are substantially higher for fluids having Reynolds number ("Re)" in a first range compared to fluids having Re in a second range.

In another aspect, a method of making a flow control device for use in a wellbore for controlling flow of a fluid from a formation into the wellbore is provided. The method, in one embodiment, may include: defining a flow rate for the fluid inflow control device; selecting a geometry for a flow-through region of the flow control device sufficient to cause a pressure drop across the flow-through region that is substantially greater for fluids having viscosity or density in a first range compared to fluids having viscosity or density in a second range for the defined flow rate; and forming the flow control device having the selected geometry.

In yet another aspect, the disclosure herein provides a computer-readable medium, accessible to a processor, having embedded thereon a computer program for executing instructions contained in the computer program, the computer program including: (a) instructions to access a flow rate for a flow control device; (b) instructions to access a first geometry for a flow-through region of the flow control device formed on a tubular member, the flow-through region including an inlet, an outlet and a tortuous path between the inlet and the outlet configured to induce turbulence in the flow of the fluid between the inlet and the outlet sufficient to reduce an effective flow area of the outlet to cause a pressure drop across the outlet that is substantially greater for fluids having viscosity or density in a first range compared to fluids having viscosity or density in a second range for the defined flow rate; instructions to compute pressure drops across the outlet based on the first geometry corresponding to a plurality of fluid viscosities or fluid densities; (c) instructions to determine if the computed pressure drops are acceptable; (d) instructions to selected a different geometry when the computed pressure drops are not acceptable and repeating (b) and (c) using the different geometry until the pressure drops are acceptable; and (e) storing the geometry for which the pressure drops are acceptable.

Examples of the more important features of the disclosure have been summarized rather broadly in order that detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will form the subject of the claims appended hereto.

The advantages and further aspects of the disclosure will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which like reference characters designate like or similar elements throughout the several figures of the drawing, and wherein: FIG. 1 is a schematic elevation view of an exemplary multi-zone welibore that has a production string installed therein, which production string includes a number of ICDs placed at selected locations along the length of the production string; FIG. 2 is a graph showing pressure drop as a function of fluid viscosity for certain types of available flow control device and also a desired pressure drop for a flow control device for controlling flow of water therethrough; FIG. 3 is a graph showing a desired relationship between Reynolds number and a pressure loss coefficient for a flow control device for controlling flow of water therethrough; FIG. 4 is an isometric view of a flow control device including a particulate filtration device and a passive flow control device in accordance with one embodiment of the

disclosure;

FIG. 5 shows an exemplary structural flow pattern or flow channel for a flow control device made according to one embodiment of the disclosure; FIG. 6 is a flow diagram showing simulation results of flow velocity of water for a multi-stage flow channel, such as shown in FIG. 5; FIG. 7 is a flow diagram showing simulation results of flow velocity of an oil having viscosity of 189cP for the multi-stage channel shown in FIG. 5; FIG. 8 shows laboratory test results of pressure drop versus viscosity for an exemplary orifice device, a helical device, a hybrid device and also a desired pressure drop for a flow control device for controlling flow of water therethrough; FIG. 9 shows an isometric view of a flow control device made according to one

embodiment the disclosure;

FIG. 10 shows the fluid flow paths for illustrative channels of the flow control device shown in FIG. 9; FIG. 11 shows a flow channel that may be utilized in a flow control device made

according to an embodiment of the disclosure;

FIG.12 shows another flow channel that may be utilized in a flow control device made according to another embodiment of the disclosure; FIG.13 shows yet another flow channel that may be utilized in an inflow control device made according to yet another embodiment of the disclosure; and FIG.14 shows yet another flow channel that may be utilized in an inflow control device made according to yet another embodiment of the disclosure.

The present disclosure relates to apparatus and methods for controlling flow of formation fluids in a well. The present disclosure provides certain drawings and describes certain embodiments of the apparatus and methods, which are to be considered exemplification of the principles described herein and are not intended to limit the disclosure to the illustrated and described embodiments.

Referring initially to FIG. 1, there is shown an exemplary fluid production system that includes a wellbore 110 drilled through an earth 112 and into a pair of production zones or reservoirs 114, 116 from which the production of hydrocarbons is intended. The wellbore 110 is shown lined with a casing having a number of perforations 118 that penetrate and extend into the formations production zones 114, 116 50 that production fluids may flow from the production zones 114, 116 into the wellbore 110. The exemplary wellbore 110 is shown to include a vertical section llOa and a substantially horizontal section 11 Ob. The wellbore 110 includes a production string (or production assembly) 120 that includes a tubing (also referred to as the base pipe) 122 that extends downwardly from a wellhead 124 at the surface 126 of the wellbore 110. The production string 120 defines an internal axial bore 128 along its length. An annulus 130 is defined between the production string 120 and the wellbore casing. The production string 120 has a deviated, generally horizontal portion 132 that extends along the deviated leg 11 Ob of the wellbore 110. Production devices 134 are positioned at selected locations along the production string 120. Optionally, each production device 134 is isolated within the wellbore 110 by a pair of packer devices 136. Although only two production devices 134 are shown along the horizontal portion 132, there may, in fact, be a large number of such production devices arranged along the horizontal portion 132.

Each production device 134 features a production control device (or flow control device) 138 used to govern one or more aspects of flow of one or more fluids from the production zones into the production string 120. As used herein, the term "fluid" or "fluids" includes liquids, gases, hydrocarbons, multi-phase fluids, mixtures of two of more fluids, water and fluids injected from the surface, such as water. Additionally, references to water should be construed to also include water-based fluids; e.g., brine or salt water. In accordance with embodiments of the present disclosure, the flow control device 138 may have a number of alternative structural features that provide selective operation and controlled fluid flow therethrough.

Subsurface formations typically contain water or brine along with oil and gas. Water may be present below an oil-bearing zone and gas may be present above such a zone. A horizontal wellbore, such as section IlOb, is typically drilled through a production zone, such as production zone 116, and may extend to more than 5,000 feet in length. Once the welibore has been in production for a period of time, water flow into some of the flow control devices 138. The amount and timing of water inflow can vary along the length of the production zone. It is desirable to have flow control devices that will restrict the flow of fluids when a selected amount of water is present in the production fluid. In an aspect, by restricting the flow of production fluid containing water, the flow control device enables more oil to be produced over the production life of the production zone.

FIG. 2 shows a graph 200 illustrating the pressure drop behavior of certain types of lCDs for fluids of different viscosities. The pressure drop ip" across the device is shown along the vertical axis and the fluid viscosity "p' is shown along the horizontal axis. The viscosity of pure water is 1 cP and the viscosity of the majority of oils present in subsurface formations is between lOcP-200cP. Curve 202 depicts the pressure drop for an orifice-type lCD, in which most of the pressure drop occurs at the orifice and it is a function of the diameter of the orifice. The total pressure drop across the orifice-type lCD is generally the sum of the pressure drops across all the orifices contained in the lCD. It can be seen that the pressure drop increases sharply as the fluid viscosity increases. In particular, the pressure drop for most oils is greater than the pressure drop for water. Curve 204 corresponds to a helical type lCD, in which the production fluid flows along a relatively long helical path around a tubular member. Curve 204 shows that the pressure drop for water is greater than the pressure drop for fluids with viscosity up to about 6OcP. The pressure drops for water and for fluids with viscosity up to about 2OcP and it starts to rise for fluids with viscosity greater than about 20cR Curve 204 indicates some blockage of water and also that of oils above 2OcP viscosity. Curve 206 corresponds to a hybrid design that includes orifices separated by a tortuous flow path. One such lCD is described in U.S. Patent Application Serial No. 12/417,346, filed on April 2,2009, assigned to the assignee of this application, which is incorporated herein by reference in its entirety. Curve 206 shows that the change in the pressure drop across such devices is higher than the change in pressure drop across helix-type devices and further that the pressure drop continues to decrease for fluids with viscosity up to about 6Ocp. This shows that the such devices provide water blockage and that less obstruction certain types of oils compared to the helix-type devices. Devices that correspond to the curve 206 tend to better inhibit the flow of water into the wellbore compared to the orifice and helical devices. The data shown for curves 202, 204 and 206 is obtained from laboratory test results.

Still referring to FIG. 2, It is desirable to provide flow control devices that will increase pressure drop for low viscosity fluids, such as fluids having viscosity below about 6cR or 1 OcP, and substantially constant pressure drop for fluids having viscosity in a range above 6cP or 1 OcR. The pressure drop may increase exponentially as the viscosity decreases in such ranges. Curve 208 shows a more desired pressure drop behavior for a fluid flow through the flow control device, wherein the pressure drop is substantially greater for fluids with viscosities in a first range, such as viscosities below about I OcP, and substantially constant for fluids with viscosities in a second range, such as above about 6cR or IOcP, FIG. 3 shows a graph 300 of a desired performance curve for a flow control device expressed as a relationship between Reynolds number "Re" and pressure loss coefficient "K." The Re is shown along the vertical axis and K along the horizontal axis. Reynolds number Re is dimensionless and is a ratio between inertia forces and viscous forces. Re for fluids may be expressed as: Re = Inertia forces / viscous force Re = (p. V. dv/dx) / p. d2v/dx2 Re = p V D / p, wherein p is density of the fluid, V is flow volume, v is the fluid velocity, D is a dimension of the flow area, such as diameter of an opening, and p is the viscosity of the fluid. The Reynolds number for low viscosity fluids, such as water is relatively high compared to the high viscosity fluids, such as oils. Therefore, Re may also be expressed as: Re = f(density, viscosity, fluid velocity and surface dimension(s)) Pressure drop Dp across a flow area A may be expressed as: Dp=K.(p/A2). v2, where A is the flow area. The pressure loss coefficient K is a function of Reynolds number Re (K f (Re)). The inventors have determined that K also is a function of the geometry of the flow path of the fluid through the flow control device and in particular the tortuosity of the flow path within the flow control device, and that therefore inducing turbulence in the flow of a fluid affects the pressure drop of fluids of different viscosities, as described in more detail later. The pressure loss coefficient K may be expressed as: K f(Re, opening size, tortuosity) Graph 300 shows demonstrates that it is desirable to have a flow control device that exhibits a high value of pressure loss coefficient K for fluids with a Reynolds number higher than the Reynolds number for water 301, as shown by the curve segment 302. Graph 300 also shows that it desirable to have a relatively constant pressure loss coefficient K for Reynolds numbers less than the Reynolds number for water 301, as shown by the curve segment 306. The overall behavior of a fluid through an lCD depends upon the rheology of the fluid. Rheology is a function of several parameters, including, but not limited to, flow area, tortuosity, friction, fluid velocity, fluid viscosity and fluid density. In aspects, rheology parameters may be calculated or assumed to provide flow control devices that will inhibit water flow. The disclosure herein utilizes fluid rheology principles and other factors noted above to provide flow control devices that inhibit flow of fluids with viscosity or density in one range and allow a substantially constant flow of fluids with viscosity or density in another range. Exemplary flow control devices and methods of making such devices are described in reference to FIGS. 4-14.

Referring now to FIG. 4, there is shown one embodiment of a production device 400 for controlling the flow of fluids from a reservoir into a production string. The device 400 is shown to include a particulate control device or filtration device 410 for reducing the amount and size of particulates entrained in the fluids and an lCD 450 that controls the overall drainage rate of the formation fluid 455 into the wellbore. In one embodiment the filtration device 410 may include a shroud 412 placed around a tubing 402, a filtration media 414 placed between the shroud 412 and the tubing 402, and a flow path 416 placed between the filtration media 414 and a tubular 418. Formation fluid flows into the shroud 412, which has a pattern of perforations that allow the formation fluid to flow into the filtration device 410. Shroud 412 insulates the components of the filtration device 410 from direct exposure to the formation fluid containing solid particles and relatively high velocity fluids. In addition, the shroud 412 inhibits the flow of large solid particles from entering the filter media 414. Filter media 414 filters relatively small solid particles and allows the formation fluid to flow into the fluid flow path 416, and then into the flow control device 450.

Exemplary flow control devices are described herein below.

FIG. 5 shows an exempFary structural flow pattern for a flow control device 500 made according to one embodiment of the disclosure. The flow control device 500, in one aspect, may include an inflow region 510 and outflow region 520 and a flow-through region 530. The flow-through region 530 may further include one or more stages, such as stages 530a, 530b, 530c, etc. In the flow configuration of flow control device 500, formation fluid 501 enters the inflow region 510, which fluid then enters the first stage 530a via a port or an opening 532a and discharges from a port 532b into the second stage 530b, The fluid from the second stage 530b discharges into the next stage 530c via port 532c and then into the oufflow region 520 via port 532d.

In aspects, the first stage 530a may have a width or axial flow distance xl and a height or radial distance yl. The offset or misalignment between the inlet port 532a and the outlet port 532b for stage 530a is denoted by hi. Similarly, the axial flow distance, radial distance, and outlet ports for subsequent stages 530b and 530c are respectively denoted by x2,h2 and d3, and x3,h3 and d4. The fluid path through such stages is denoted by Fpi, Fp2 and Fp3. The first substantial pressure drop Dpi occurs at the port 532a. The fluid 501 then flows along a tortuous path Fpi and exits through port 532b. The second pressure drop Lxp2 occurs at port 532b. Similarly, subsequent pressure drops occur at ports 532c and 532d. In an embodiment, the majority of the pressure drops occur at the ports. The pressure drop across the device 500 is approximately the sum of the pressure drops at each stage, namely api, Ap2 and Ap3. As noted earlier, for a given fluid type (viscosity, density, etc.) and a flow rate, the pressure drop depends upon the flow areas, tortuosity of flow path, etc. In one aspect, each stage in the flow control device 500 may have same physical dimensions. In another aspect, the radial distance, port offset and port size may be chosen to provide a desired tortuosity so that the pressure drop will be a function of the fluid viscosity or density. In other aspect, the dimension of such stages may be different. It has been determined that an flow control device made according to the aspects shown in FIG.5 may provide higher pressure drop for fluids having relatively low viscosity, for example less than 1 OcP, and a substantially constant pressure drop for fluids having viscosity in a range above iOcP. In general, the pressure drop across a port, such as port 532b is a function of offset (h), axial distance (x) and a port dimension (d). In one aspect, the relationship may be xlh > d/h. In another aspect, dimension h may be 4-6 times d.

FIG. 6 is a flow diagram 600 showing simulation results of flow velocity of water for a multi-stage (630a-630g) flow control device such as shown in FIG. 5, wherein path lines are colored by velocity magnitude (ftlsec). The velocity of fluid increases as the fluid 601 progresses from one stage to the next. Loops, such as loop 640a and 640b in stage 632a, indicate that fluid has a relatively low velocity and may thus be considered substantially non-flowing through the stage 630a. The fluid 601 flows along a tortuous flow path 650a in the first stage 632a, which flow path includes an axial path 650a and a radial path 650b.

The offset or misalignment between the ports is "h." The fluid 601 then exits the port 660b.

The tortuosity of the fluid path 650 and the corresponding pressure drop at port 660b may be controlled by the combination of axial distance, radial distance, offset and port size.

Accordingly, in an embodiment, a flow control device may be designed to restrict the flow of a fluid containing water by selecting the corresponding axial distance, radial distance, offset and port size to cause a significant pressure drop across the flow control device.

FIG. 7 is a flow diagram 700 showing simulation results of flow velocity of an oil having viscosity of 189cP for the multi-stage (630a-630g) flow control device shown in FIG. 6, wherein path lines are colored by velocity magnitude (ft/sec). The velocity of fluid increases as the fluid 701 progresses from one stage to the next. Loops, such as loop 740a and 74Gb in stage 630a, indicate that fluid has a relatively low velocity and may thus be considered substantially non-flowing through the stage 630a. It should be noted that these velocity loops are less intense when compared to loops 640a and 64Gb for water.

The fluid 701 flows along a tortuous flow path 750a in the first stage 630a, which flow path includes a first substantially axial path 650a and a second substantially radial path 65Gb.

The radial path 65Gb substantially equal to the offset distance "h.' The fluid 701 then exits the port 660b. The tortuosity of the fluid path 650 and the corresponding pressure drop at port 66Gb may be controlled by choosing the combination of axial distance, offset and the port size. Higher turbulence tends to create higher pressure drop across the ports of devices, such as shown in FIG. 7.

FIG. 8 shows an exemplary comparison chart 800 of pressure drops relative to water for an orifice-type device, helical device, a hybrid device and a device, such as shown in FIGS. 6 and 7. The percent pressure drop change relative to water is depicted along the vertical axis and the viscosity of the fluid along the horizontal axis. Curve 802 corresponds to an orifice type flow control device, curve 804 corresponds to a helical device, curve 806 corresponds to a hybrid device and curve 808 corresponds to a flow control device of the type shown in FIGS. 6 and 7. It is noted that a flow control device made according to the principles described in reference to FIGS. 6 and 7 exhibits relatively high percentage pressure drop change for low viscosity fluid, such as fluids in the viscosity range shown by 810a (up to about 1GcP) and a substantially constant pressure drop for fluids in the viscosity range 81Gb (from about 10cR to l8OcP).

FIG. 9 shows an isometric view of an embodiment of a passive flow control device 900 made according the principles described herein. The flow control device 900 is shown to include a number of structural flow sections 920a, 92Gb, 92Gc and 920d formed around a tubular member 902, each such section defining a flow channel or flow path. Each section may be configured to create a predetermined pressure drop to control a flow rate of the production fluid from the formation into the welibore tubing. One or more of these flow paths or sections may be occluded (not in hydraulic communication with another section) in order to provide a selected or specified pressure drop across such sections. Fluid flow through a particular section may be controlled by closing ports 938 provided for the selected flow section. The total pressure drop across the device 900 is the sum of the pressure drops created by each active section. Structural flow sections 920a-920d may also be referred to as flow channels. To simplify description of the device 900, the flow control through each channel is described in reference to channel 92Ga. Channel 92Ga is shown to include an inflow region 910 and an outflow region or area 912. Formation fluid enters the channel 920a into the inflow region 910 and exits the channel via outflow region 912. Channel 920a creates a pressure drop by channeling the flowing fluid through a flow-through region 930, which may include one or more flow stages or conduits, such as stages 932a, 932b, 932c and 932d. Each section may include any desired number of stages. Also, in aspects, each channel in a device may include a different number of stages. In another aspect, each channel or stage may be configured to provide an independent flow path between the between the inflow region and the outflow region. As noted earlier, some or all of channels 920a-920d may be substantially hydraulically isolated from one another. That is, the flow across the channels and through the device 900 may be considered in parallel rather than in series. Thus, the flow across one channel may be partially or totally blocked without substantially affecting the flow across another channel. It should be understood that the term "parallel" is used in the functional sense rather than to suggest a particular structure or physical configuration.

Still referring to FIG. 9, there are shown further details of the flow control device 900 which creates a pressure drop by conveying the in-flowing fluid through one or more of the plurality of channels 920a-920d. Each of the channels 920a-920d may be formed along a wall of a base tubular or mandrel 902 and include structural features configured to control flow in a predetermined manner. While not required, the channels 920a-920d may be aligned in a parallel fashion and longitudinally along the long axis of the mandrel 902.

Each channel may have one end 132 in fluid communication with the wellbore tubular flow bore 402 (FIG. 4) and a second end 134 (FIG. 3) in fluid communication with the annular space or annulus separating the flow control device 120 and the formation. Generally, channels 920a-920d may be separated from one another, for example in the region between their respective inflow and outflow regions.

In embodiments, the channel 920a may be arranged as a maze or labyrinth structure that forms a tortuous or circuitous flow path for the fluid flowing therethrough. In one embodiment, each stage 932a-932d of channel 922a may respectively include a chamber 942a-942d. Openings 944a-944d hydraulically connect chambers 942a-942d in a serial fashion. In the exemplary configuration of channel 920a, formation fluid enters into the inflow region 910 and discharges into the first chamber 942a via port or opening 944a.

The fluid then travels along a tortuous path 952a and discharges into the second chamber 942b via port 944b and so on. Each of the ports 944a-944d exhibit a certain pressure drop across the pod that is function of the configuration of the chambers on each side of the port, the offset between the ports associated therewith and the size of each port. The stage configuration and structure within determines the tortuosity and friction of the fluid flow in each particular chamber, as described herein. Different stages in a particular channel may be configured to provide different pressure drops. The chambers may be configured in any desired configuration based on the principles, methods and other embodiments described herein.

FIG. 10 shows the fluid flow paths for the four illustrative channels 920a-920d of the flow control device 900. For ease of explanation, the flow control device 900 is shown in phantom lines and "unwrapped" in order to better depict the channels 920a-d in a flat plane, as opposed to the tubular depiction of FIG, 9. Each of these channels 920a-9202d provides a separate and independent flow path between the annulus or formation and the tubular bore 402 (HG. 4), as shown by flow paths 1020a-1020d. Also, in the embodiment shown, each of the channels 920a-920d provides a different pressure drop for a flowing fluid. The channel 920a is constructed to provide the least amount of resistance to fluid flow and thus provides a relatively small pressure drop. The conduit 920d is constructed to provide the greatest resistance to fluid flow and thus provides a relatively large pressure drop. The conduits 920b and 920c provide pressure drops in a range between those provided by the conduits 920a and 920d. It should be understood, however, that in other embodiments, two or more of the conduits may provide the same pressure drops or that all of the conduits may provide the same pressure drop. As noted earlier, fluid flow from any of the channels may be either partially or completely blocked. Thus, the fluid flow across the flow control device 900 may be adjusted by selectively occluding one or more of the channels 920a-920d. The number of permutations for available pressure drops, of course, varies with the number of channels, which may be one or more as desired. Thus, in embodiments, the flow control device 900 may provide a pressure drop associated with the flow across one channel, or a composite pressure drop associated with the flow across two or more channels. Such a device may be configured at the field and differently configured devices may be placed along the wellbore.

Additionally, in embodiments, some or all of the surfaces of the channels 920a- 920d may be constructed to have a specific frictional resistance to flow. In some embodiments, the friction may be increased using textures, roughened surfaces, or other such surface features. Alternatively, friction may be reduced by using polished or smoothed surfaces. In embodiments, the surfaces may be coated with a material that increases or decreases surface friction. Moreover, the coating may be configured to vary the friction based on the nature of the flowing material (e.g., water or oil). For example, the surface may be coated with a hydrophilic material that absorbs water to increase frictional resistance to water flow or a hydrophobic material that repels water to decrease frictional resistance to water flow.

FIG. 11 shows an exemplary channel or flow channel 1100 that may be utilized in an inflow control device made according to one embodiment of the disclosure. Such a flow control device may include one or more such flow channeFs or a combination of channels.

For illustration purposes, channel 1100 is shown to include stages 1102a-1102d, each of which respectively includes a chamber or flow area 11 04a-1 104d and a corresponding outflow port or conduit 1106a-1106d. The fluid flow regime shown in FIG. 11 is a result of simulation for water flowing through the channel 1100. Formation fluid 1101 enters the first chamber 11 04a via a conduit 1106a and discharges into chamber 11 04b via conduit 11 06b. The fluid path 11 20a in the first chamber 11 02a is defined by the straight section 1122a of chamber 1102a and the offset hi between conduits 1106a and 1106b. The pressure drop occurs at opening of conduit 1 106b. The flow path in subsequent chambers is defined by similar physical parameters. The physical configuration of the stages may be -11 -, designed to provide a substantially high pressure drop for fluid with viscosities or densities in a first range (such as fluids containing water) and a substantially constant pressure drop in a second range (such as fluids containing mostly oil). Simulation results show that for water for a given mass flow (volume), the pressure drop Ap across stages 1102a-1102c is approximately 4.88 times the pressure drop relative to water flowing in a straight pipe section. The amount of the pressure drop may vary by the choice of chamber and conduit parameters. Areas 1 130a-1i 30d respectively show zones that do not significantly affect the pressure drop across their respective stages. In addition, the structure and configuration of the chambers defines the tortuosity and turbulence induced in the flowing fluid, defines the reduction in the effective opening of each port between chambers. For example, a chamber that causes a significant amount of turbulence may cause only about 70% of a port's opening to allow fluid flow, due to substantial resistance in and around the port. This behavior may also be selectively controlled to produce a desired pressure drop across each stage.

FIG.12 shows a flow channel 1200 that may be utilized in an inflow control device made according to another embodiment of the disclosure. For illustration purposes, channel 1200 is shown to include stages 1202a-1202d, each of which respectively includes a chamber 1 204a-i 204d coupled by a corresponding conduit I 206a-1 206d. The fluid flow regimes shown in FIG. 12 are simulation results for water flowing through the channel 1200, Formation fluid 1201 enters the first chamber 1204a via a conduit 1206a and discharges into chamber 1 204b via conduit 1 206b. The fluid path 1 220a in the first chamber 1204a is defined by the curved section 1222a of chamber 1204a and the offset hi between conduits 1 206a and 1 206b. The pressure drop occurs at outflow port of each conduit. The flow path in each of the subsequent stages 1202b-120d is defined by similar physical parameters. The physical or structural configuration of each stage may be designed so as to provide a substantially high pressure drop for fluids with viscosities or densities in a first range (such as fluids containing water) and a substantially constant pressure drop for fluids with viscosities or densities in a second range (such as fluids containing mostly oil). Simulation results show that for given volume of water flow, the pressure drop Ap across stages 1202b-1202c is approximately 5.60 times the pressure drop for same volume of water flowing in a straight pipe section. The amount of the pressure drop may varied by the choice of parameters of each stage. Areas i230a-1230d correspond to zones that do not significantly contribute to the pressure drops.

FIG. 13 shows another flow channel 1300, which may be utilized in yet another embodiment of a flow control device made according to the disclosure. The channel 1300 is shown to be a Z-shaped channel, which includes a first substantially straight section 1310, a first angled or bent section 1320, a second substantially straight section 1330, a second angled or bent section 1340 and a third substantially straight section 1350. Flow paths shown in FIG. 13 are the results of simulation for water flow through the section 1300. In the flow channel 1300, turbulences induced in the flow reduce the effective flow area proximate each bend. For example, area 1360 shows relatively negligible fluid flow or a dead area, which reduces the available flow area along the bend 1320. Similarly, a relatively dead or no-flow area 1362 reduces the effective flow area proximate bend 1340 and area 1364 reduces the flow area in section 1350 proximate the bend 1340. Simulation results show that the pressure drop for water in a particular embodiment is about 4.11 relative to the pressure drop for water in a pipe section.

FIG. 14 shows flow channel 1400, in which formation fluid 1401 flows form an inflow region 1402 into a contoured or tortuous path 1410 that includes a first bend 1420. ln one aspect, the loop around adds inertia tangential to the bends, which may increase pressure drop across the second bend 1422. The fluid then loops around a member 1430 and exits via a second bend 1422. The angles 1421 and 1423 of the bends 1420 and 1422 may be chosen to provide selected pressure drops so that the total pressure drop across the channel 1400 is substantially higher for fluids having viscosities or densities in a first range (such as fluids containing for water) and a substantially lower and constant pressure drop for fluids having viscosities or densities in a second range (such as fluids containing mostly oils). One or more bends may have an acute angle (less than 90 degrees). Simulation results show that for water, the pressure drop across a particular configuration of channel 1400 may be between 4.2 to 5.02 times the pressure drops across a straight pipe section.

In another aspect, the disclosure herein provides a method of determining the configuration of one or more flow channels for inflow devices that may provide substantially high pressure drop for fluids having viscosities or densities in a first range compared to the pressure drop for fluids having viscosities or densities in a second range. A set of fluid parameters is defined for a particular application, which parameters may include the flow rate or bulk volume desired for the inflow device, fluid viscosity and/or density ranges, etc. An initial set of parameters for an inflow device may then be selected or defined, which parameters, for example, may include one or more of: number of stages, surface area for each stage, stage geometries, offset between flow ports, axial travel distance for the fluid in each stage, angle of bend for the flow path, curvature of the flow paths, etc. A behavior of pressure drop versus viscosity of the fluid flowing through the specified lCD is determined using a computer system and a simulation model. The simulation may also be performed to provide pressure drops through each stage, fluid flow velocity patterns, reduction in effective flow areas along the fluid paths, etc. The results of the simulated or calculated pressure drops for different ranges of viscosities or densities may be compared to desired pressure drops. If the results differ more than an acceptable value, one or more initial parameters for the flow control device are altered and the simulation process repeated.

This iterative process may be continued using new values of one or more inflow device parameters until a satisfactory pressure drop relationship is obtained. Alternatively, the relation ship between Reynolds number (Re) and coefficient of friction (K) may be determined at end of each simulation run to determine an inflow device configuration that will provide higher pressure drop for unwanted fluids, such as water, and a relatively constant pressure or laminar flow for certain other fluids, such as oils. The amount of turbulence induced along the fluid path in the inflow device, reduction in the effective flow areas along at ports or along bends, etc may be determined from flow velocity patterns and utilized to select parameters of the inflow device prior to each simulation run. The -13-exemplary channels for flow control devices are described herein as axially placed channels in a tubular. However, such and other channels made according the teachings herein may be placed radially, helically or along any other angle. Additionally, such flow control devices may utilize different types of channels in a single device.

Thus, in one aspect, the disclosure herein provides an apparatus for controlling flow of fluid between a reservoir and a wellbore, which apparatus in one embodiment may include a flow-through region configured to substantially increase value of a selected parameter relating to the flow flow-through region when a selected property of the fluid is in a first range and maintain a substantially constant value of the selected parameter when the selected property of the fluid is in a second range.

In another aspect, the flow control device may include a flow-through region configured to substantially increase pressure drop across the flow-through region when a selected property of the fluid is in a first range and maintain a substantially constant pressure drop across the flow-through region when the selected property of the fluid is in a second range.

In another embodiment, the flow control device may include an inflow region, a flow-through and an outf low region, wherein the flow-through region is configured to substantially increase pressure drop when viscosity or density of the fluid is in a first range and maintain a substantially constant pressure drop when the viscosity or density of the fluid is in a second range. In one aspect, the first range may include viscosities less than 10cR and the second range may include viscosities above 10cR. Alternatively, the first range may include densities more than 8.33 lbs per gallon and the second range include densities less than 8.33 lbs per gallon. In one aspect, the flow-through region may be configured to induce selected amounts of turbulences in fluids having viscosities or densities in the first range to provide a desired pressure drop across the flow-through region for a given fluid flow rate through flow-through area. In another aspect, the flow-through region may include a structural area configured to receive the fluid via a first port and discharge the received fluid via a second port having a dimension "d", the structural area having an axial distance "x", there being an offset "h" between the first port and the second port. In one embodiment, h may be between 4 to 6 times d. In another embodiment hlx is greater than d/h. In another embodiment, the flow-through region may be configured to include a tortuous path.

In another aspect, the disclosure provides a flow control device that may include: a flow-through region including a structural flow area, an inflow opening and an outflow opening, wherein the structural flow area, a fluid flow path in the structural flow area between the inflow opening and the outflow opening, tortuosity of the fluid flow path and size of the outflow opening are selected so that value of a fluid performance co-efficient ("K") is substantially greater for fluids having low Reynolds number ("Re)" in a first range compared to fluids having high Re in a second range.

In another aspect, a method is provided that may include: defining a flow rate for the fluid flow-through the inflow control device; selecting a geometry for the flow-through region formed on a tubular member, the flow-through region including an inlet, an outlet -14-and a flow path between the inlet and the outlet configured to induce turbulence in the flow of the fluid between the inlet and the outlet sufficient to reduce an effective flow area through the outlet to cause a pressure drop across the outlet that is substantially greater for fluids having viscosity or density in a first range compared to fluids having a viscosity or density in a second range for the defined flow rate; and forming the tubular member having the selected geometry.

In yet another aspect, a computer-readable medium is provided that is accessible to a processor for executing instruction in a program embedded in the computer-readable medium, which program may include: (a) instructions to access a flow rate for a fluid flow control device; (b) instructions to access a first geometry for a flow-through region of the inflow control device formed on a tubular member, the flow-through section including an inlet, an outlet and a tortuous path between the inlet and the outlet configured to induce turbulence in the flow of the fluid between the inlet and the outlet sufficient to reduce the effective flow area through the outlet to cause a pressure drop across the outlet that is substantially greater for fluids having viscosity or density in a first range compared to fluids having a viscosity or density in a second range for the defined flow rate; (c) instructions to compute pressure drops across the outlet based on the first geometry corresponding to a plurality of fluid viscosities or fluid densities; (d) instructions to compare the computed pressure drops corresponding to the first range and the second range to desired values; (e) instructions to repeat steps c and d using one or more additional geometries until the computed pressure drops are within acceptable values; and (e) instructions to store a geometry having pressure drops that meet the desired values.

It should be understood that FIGS. 1-14 are intended to be merely illustrative of the teachings of the principles and methods described herein and which principles and methods may applied to design, construct and/or utilizes inflow control devices.

Furthermore, foregoing description is directed to particular embodiments of the present disclosure for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope of the disclosure. -15-

Claims (19)

1. Claims 1. A method of providing a flow control device for controlling flow of fluid between a formation and a wellbore comprising: S defining a flow rate of the fluid through the flow control device; defining a desired relationship between a performance parameter of the flow control device that exhibits a substantial change when a selected property of the fluid changes in a first range and remains substantially constant when the selected property is in the second range; determining using a computer and a simulation program the relationship between the performance parameter and the selected property over the first range and the second range for the defined flow rate for a geometry of a flow through area of a flow control device; comparing the determined relationship of the performance parameter with the desired relationship; altering the geometry to a new geometry when the difference between the desired performance and the determined performance is outside a desired range; determining using the computer and the simulation program the relationship between the performance parameter and the selected property over the first range and the second range for the defined flow rate for the new geometry of the flow through area of the flow control device; repeating the process of altering the geometry and determining the performance until the difference between the desired performance and the determined performance for a geometry is acceptable; and storing the geometry of the flow through device on a suitable storage medium for which the difference between the determined performance and the desired performance isacceptable.
2. 2. The method of claim 1, further comprising making the flow control device having the stored geometry on a tubular member.
3. 3. The method of claim 1, wherein the performance parameter is pressure drop across the flow-through region and the selected property is one of viscosity and density of the fluid.
4. 4. The method of claim 3, wherein the first range includes one of: (i) viscosities below about 10 cP; and (ii) densities above about 8.33 lbs per gallon.
5. 5. The method of claim 1 wherein the first range corresponds to fluids containing water or gas and the second range corresponds fluid containing mostly crude oils. -16-
6. 6. The method of claim 1, wherein the geometry of the flow-through region includes a tortuous path between an inlet for receiving the fluid and an outlet for discharging the received fluid, wherein the tortuous path induces turbulences in the fluid based on the water or gas content in the fluid that changes an effective area for the travel of the fluid proximate the outlet.
7. 7. The method of claim 3, wherein the pressure drop across the tortuous path varies as a function of the property of the fluid in the first range.
8. 8. The method of claim 4, wherein the tortuous path includes an acute bend and wherein the pressure drop proximate the acute bend changes as the value of the selected property of the fluid in the first range changes.
9. 9. The method of claim 1, wherein the geometry of the flow-through region includes one of: a z-shaped fluid flow path; an s-shaped fluid flow path; and a fluid flow path that includes a circular path and an acute bend.
10. 10. The method of claim 1 wherein the performance parameter is a performance coefficient as a function of Reynolds number of the fluid.
11. 11. The method of claim 1 further comprising selecting the geometry from a set of geometries.
12. 12. A computer-readable medium, accessible to a processor, having embedded thereon a computer program for executing instructions contained in the computer program, the computer program including: a. instructions to access a flow rate for a fluid flow control device; b. instructions to access a desired relationship between a performance parameter of the flow control device that exhibits a substantial change when a selected property of the fluid changes in a first range and remains substantially constant when the selected property of the fluid is in the second range; c. instructions to use a simulation program to determine the relationship between the performance parameter and the selected property of the fluid over the first range and the second range for the defined flow rate for a geometry of a flow through area of a flow control device; d. instructions to compare the determined relationship of the performance parameter and the selected parameter with the desired relationship; e. instructions to repeat steps c and d using one or more additional geometries of the flow-through region until the difference between the determined relationship between the performance parameter and the selected property and the desired relationship between the performance parameter and the selected property is acceptable; and f. instructions to store the geometry of the flow-through region that corresponds to the results of step e.
13. 13. The computer-readable medium of claim 12, wherein the performance parameter is pressure drop across the flow-through region and the selected property is one of viscosity and density of the fluid.
14. 14. The computer-readable medium of claim 12, wherein the first range includes one of: (i) viscosities below about 10 cP; and (ii) densities above about 8.33 lbs per gallon.
15. 15. The computer-readable medium of claim 12, wherein the first range corresponds to fluids containing water or gas and the second range corresponds fluid containing mostly crude oils.
16. 16. The computer-readable medium of claim 12, wherein the geometry of the flow-through region includes a tortuous path between an inlet for receiving the fluid and outlet for discharging the received fluid, wherein the tortuous path induces turbulences in the fluid based on the water or gas content in the fluid that changes an effective are for the travel of the fluid proximate the outlet.
17. 17. The computer-readable medium of claim 12, wherein the pressure drop across the tortuous path varies as a function of the property of the fluid in the first range.
18. 18. The computer-readable medium of claim 17, wherein the tortuous path includes an acute bend and wherein the pressure drop proximate the acute bend changes as the value of the selected property of the fluid in the first range changes.
19. 19. The computer-readable medium of claim 12, wherein the geometry of the flow-through region includes one of: a z-shaped fluid flow path; an s-shaped fluid flow path; and a fluid flow path that includes a circular path and an acute bend.