Inflow Control Device for Polymer Injection in Horizontal Wells

Abstract

A flow balancing device facilitates polymer injection in a horizontal formation in a manner that minimizes shear effects on the injected polymer. Features of the device reduce velocity using a broad circumferentially oriented inlet plenum that leads to a circumferentially oriented path having zig-zag fluid movement characterized by broad passages that define the zig-zag pattern so as to reduce velocity at such transition locations. Because the path is circumferentially oriented there is room for broad transition passages independent of the housing diameter. The broad crescent shaped inlet plenum also reduces inlet velocity, and therefore shear, to preserve the viscosity of the injected polymer. Other materials can be injected or the device can be employed in production service as well as injection. A related method employs the described device for injection.

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 tortuous path comprising an opposed inlet and an outlet for flow through said housing, said path extending circumferentially substantially around an inner wall of said housing in a zig-zag pattern formed substantially by axially oriented segments connected with circumferentially oriented connecting paths.

2. The assembly of claim 1, wherein: adjacent circumferentially oriented connecting paths are axially offset to define said zig-zag pattern.

3. The assembly of claim 1, wherein: said inlet is connected by a said axially oriented segment as an entry to said tortuous path.

4. The assembly of claim 1, wherein: said inlet comprises a curved slot.

5. The assembly of claim 4, wherein: said slot is wider than a said axially oriented segment.

6. The assembly of claim 4, wherein: said curved slot has an inlet flare or a rounded edge.

7. The assembly of claim 4, wherein: said outlet comprises a curved slot.

8. The assembly of claim 7, wherein: said slot is wider than a said axially oriented segment.

9. The assembly of claim 7, wherein: said curved slot has an inlet flare or a rounded edge.

10. The assembly of claim 1, wherein: said axially oriented segments extend to at least part of the axial distance between said inlet and said outlet.

11. The assembly of claim 1, wherein: said tortuous path extends circumferentially for at least 360 degrees.

12. The assembly of claim 11, wherein: said tortuous path defines a scroll shape with a variable diameter.

13. The assembly of claim 1, wherein: said axially oriented segments have a quadrilateral shape.

14. The assembly of claim 1, wherein: said circumferentially oriented connecting paths have a quadrilateral or round shape.

15. The assembly of claim 1, wherein: said at least one tortuous path extends circumferentially for at least two revolutions.

16. The assembly of claim 1, wherein: said axially oriented segments are the same or a different length; said circumferentially oriented connecting paths have the same or different shape and cross-sectional area.

17. The assembly of claim 1, wherein: said at least one tortuous path comprises a plurality of tortuous paths in said housing with flow through said tortuous paths in series or in parallel.

18. A borehole flow balancing method for production or injection, comprising: installing a tubular sting into the borehole that further comprises at least one housing having opposed end connections adapted for connection to a tubular string and at least one tortuous path comprising an opposed inlet and an outlet for flow through said housing, said path extending circumferentially substantially around an inner wall of said housing in a zig-zag pattern formed substantially by axially oriented segments connected with circumferentially oriented connecting paths; flowing fluid through said tortuous path to or from the borehole.

19. The method of claim 18, comprising: providing a curved slot for said inlet or outlet.

20. The method of claim 18, comprising: configuring said inlet or said connecting paths to reduce flow shear that can affect the viscosity of a polymer pumped therethrough using available space from orienting said tortuous path in said substantially circumferential orientation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a schematic view of a prior art device from a first orientation showing entering flow;

[0014] FIG. 2 is the view of FIG. 1 slightly rotated to show the exiting flow;

[0015] FIG. 3 is another prior art inflow control device featuring a spiral flow path;

[0016] FIG. 4 shows the orientation of the inlet and circumferential flow path leading to the outlet in the present invention;

[0017] FIG. 5 is the view of FIG. 4 showing the velocity of the flow;

[0018] FIG. 6 is the view of FIG. 4 showing the wall shear from the flow;

[0019] 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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] 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 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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: