ALTERNATIVE HELICAL FLOW CONTROL DEVICE FOR POLYMER INJECTION IN HORIZONTAL WELLS

Abstract

The flow control device comprises one or more stacked spiral paths where the shape of an inlet to an end of a spiral has a taper on one or more sides to gradually increase the polymer velocity to eliminate rapid acceleration points as the flow enters the spiral path. The entrance with its taper can be curved to get into the spiral. The spiral can be entered tangentially or radially or axially.

Claims

1. A flow control assembly for borehole use, comprising: at least one housing having opposed end connections adapted for connection to a tubular string; at least one coiled path having at least one inlet and at least one outlet and disposed in said housing, said inlet and outlet communicating with pressure in the tubular string, said inlet comprising a reduction in cross-sectional area in the direction of fluid movement into said inlet.

2. The assembly of claim 1, wherein: said reduction in cross-sectional area occurs over a predetermined linear distance.

3. The assembly of claim 1, wherein: said inlet comprising at least one tapered flat side to accomplish said reduction in cross-sectional area.

4. The assembly of claim 1, wherein: said inlet cross-section shape is round.

5. The assembly of claim 1, wherein: said inlet cross-sectional shape is a quadrilateral.

6. The assembly of claim 1, wherein: said inlet enters said coiled path tangentially.

7. The assembly of claim 1, wherein: said inlet enters said coiled path radially.

8. The assembly of claim 1, wherein: said inlet enters said coiled path axially.

9. The assembly of claim 1, wherein: said inlet enters said coiled path axially.

10. The assembly of claim 1, wherein: said at least one coiled path comprises a plurality of nested coiled paths.

11. The assembly of claim 10, wherein: each said coiled paths has a said inlet where adjacent inlets are offset from each other.

12. The assembly of claim 1, wherein: said inlet tapers to a smaller dimension and is coiled so that an end of said inlet aligns axially with an opposing end of the coiled path.

13. The assembly of claim 1, wherein: said inlet has a taper angle of as much as 30 degrees.

14. The assembly of claim 1, wherein: the cross-sectional area of said inlet decreases by as much as 50% over a length of said inlet, said inlet length being up to half the axial length of said coiled path.

15. A borehole flow balancing method for production or injection, comprising: flowing through a tubular sting in the borehole that further comprises at least one housing having opposed end connections adapted for connection to the tubular string and at least one coiled path comprising at least one inlet and at least one outlet and disposed in said housing, said inlet and outlet communicating with pressure in the tubular string, said inlet comprising a reduction in cross-sectional area in the direction of fluid movement into said inlet.

16. The method of claim 15, comprising: providing at least one tapered flat side to accomplish said reduction in cross-sectional area.

17. The method of claim 15, comprising: configuring said inlet to enter said coiled path, tangentially, radially or axially.

18. The method of claim 15, comprising: providing as said at least one coiled path a plurality of nested coiled paths wherein each said coiled paths has a said inlet where adjacent inlets are offset from each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a schematic view of a prior art device from a first orientation showing entering flow;

[0016] FIG. 2 is the view of FIG. 1 slightly rotated to show the exiting flow;

[0017] FIG. 3 is another prior art inflow control device featuring a spiral flow path;

[0018] FIG. 4 shows the orientation of the inlet and circumferential flow path leading to the outlet in the present invention;

[0019] FIG. 5 is the view of FIG. 4 showing the velocity of the flow;

[0020] FIG. 6 is the view of FIG. 4 showing the wall shear from the flow;

[0021] FIG. 7 is a performance graph showing the relatively lower velocities and wall shear of the present invention compared to the FIGS. 1-3 designs;

[0022] FIG. 8 illustrates an inlet taper configuration oriented tangentially and radially; and

[0023] FIG. 9 shows a tapering inlet that tracks the spiral curvature of the restriction path.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] FIG. 4 shows the flow path in the device without the outer housing for greater clarity. The inlet 60 extends between opposed ends 62 and 64 in between which is a height 66 so that the inlet flow represented by arrows is aligned with the crescent-shaped opening or slot that defines the inlet 60. From there the flow goes axially into passage 70 as indicated by arrow 72 and then turns circumferentially into passage 74 as indicated by arrow 76. Transition passage 78 is axially and circumferentially offset from passage 74 to induce the zig-zag flow pattern that repeats as the flow goes back and forth axially as it progresses circumferentially until reaching passage 82 to move into axial path 84 for continuation to the outlet 86 which has the same crescent shape of inlet 60 and results in flow indicated by arrows 88 exiting axially from the outlet 86 to minimize the exit velocity from the broad outlet and elimination of turns using the axial flow out of outlet 86 as indicated by arrows 88.

[0025] Variations are contemplated such as when flow exits passage 82 and enters passage 84 for axial flow, another circumferential zig-zag array can be entered or the path can continue as a scroll with a smaller diameter than the initial circumferential pass. More than two circular paths are also envisioned. The length of each axial path can be varied. What is shown is the axial paths such as 70 extending about half way between the inlet 60 and the outlet 86 with each axial path equally long. This can be varied so that the axial paths can extend further or less than shown to the point where they extend the full distance between the inlet 60 and the outlet 86. The axial paths in a given circular path can have different or the same lengths. The crossover passages between the axial runs such as 74, 76 and 82 can have the same cross-sectional areas or different areas. The shape of such openings is preferably rectangular but can also be square, round or another shape that promotes smooth flow therethrough to reduce shear effects from high velocity zones. The opening shapes for crossover passages between the axial runs such as 74, 76 and 82 can be the same or different. Since the flow regime is circumferential there is always room to extend the length of the passages such as 74 independently of the housing that is around the structure of FIG. 4 that is not shown.

[0026] The circumferential paths that can be used can be stacked axially and have the same diameter. The flow through multiple paths stacked axially can be in series or in parallel. The diameter of the circumferential paths can be the same or different. Multiple circumferential paths can also be partially or totally nested axially which means they will have differing diameters and can have series or parallel flow. Parallel flows involve multiple inlets and outlets that can be configured to be side by side in a circular array or radially nested in whole or in part with different diameters to allow for the nesting. The inlet opening 66 can have an inlet flare such as a taper or a rounded edge to reduce turbulence and resulting fluid shear that can stem from such turbulence.

[0027] FIGS. 5 and 6 respectively illustrate the velocity through the device illustrated in FIG. 4 and the wall shear. FIG. 7 is a graph with the top line representing the performance of the FIG. 3 device and the middle line the performance of the FIGS. 1 and 2 device. The present invention shown in FIG. 4 has its performance illustrated in the lowest line indicating that the peak velocities are lower which results in a lower wall shear than the known designs of FIGS. 1-3 for a given flow rate.

[0028] The FIG. 4 devices can be used in injection methods to balance flow while minimizing shear effects on a polymer or for injection other materials or even for producing from a formation.

[0029] Referring now to FIG. 8, a dual stacked spiral shape comprising coils 100 and 102 has respective inlet shapes 104 and 106. Inlet 104 has opposed sides 108 and 110 at least one of which is tapered toward the other such that the cross-sectional area at 112 is larger than the area at location 114 at the coil 100 inlet. As a result the injected polymer flowing from 112 into coil 100 increases in velocity gradually and eliminates rapid acceleration points as observed in alternative designs seen in FIG. 3 at item 42. The degree of wall taper is somewhat dependent on the available space but taper angles of 30 degrees or less are contemplated. A cross-sectional area difference over the length of the inlet can be as much as 50% and the length of the inlet can be as long as half the axial length of the associated coiled path. As shown with inlet 104 the entry orientation is tangential while the inlet 106 is illustrated as radial. Outlets 116 and 118 are shown in a more axial orientation and the illustrated inlets 104 and 106 can alternatively be oriented in a more axial orientation the same as the illustrated outlets putting them within about 30 degrees of the longitudinal axis. Although two stacked coils are shown one or more than two coils can be used. The tapers for the inlets gradually increase the injected polymer velocity to control the amount of shearing of the polymer that can adversely affect its physical properties and the needed injection rate to get the optimum production benefit from the formation.

[0030] FIG. 9 shows an axially oriented connection 120 that reduces in cross-sectional area 122 gradually as it turns to tangentially enter the coiled section 124. Here the cross-section is round and decreasing in diameter at the same time it is being coiled to enter the coil 124 tangentially which also reduces the shear effect on the polymer being pumped through. The outlet can have the same tapering feature but with the diameter growing as the flow exits the coil 124. As in the FIG. 8 version the inlet orientation can be axial or radial and the inlet cross-section can also be a quadrilateral or some other shape that gradually transitions to a smaller dimension to incrementally so as to minimize the shearing effect on the pumped polymer that flows through.

[0031] The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: