POLYMER FLOW CONTROL DEVICE

Abstract

Water injection flow control device, distinctive in that it comprises: a stack of discs or cone-like plates, the discs or cone-like plates as stacked or per se comprises in substance spiral shaped flow conduits, the spiral shaped flow conduits comprises at least one revolution, the spiral shaped flow conduit being turned about a central point or axis and departing or approaching said central point or axis for each revolution, at least some of said spiral shaped flow conduits comprises at least one of sections in series with alternating cross section area for flow and a section with serpentine-type shape for flow along the in substance spiral shaped flow conduits, said spiral shaped flow conduits has a fluid conduit length of at least 0.2 meter, an inlet operatively coupled to an inner or outer end of the spiral shaped flow conduits, an out-let operatively coupled to the other end of said conduits than the inlet, and a control member. The invention also provides a system comprising said device and use of said device.

Claims

1. A water injection flow control device comprising: a stack of discs or cone-like plates, the discs or cone-like plates as stacked or per se comprises in substance spiral shaped flow conduits, the spiral shaped flow conduits comprise at least one revolution, the spiral shaped flow conduit being turned about a central point or axis and departing or approaching the central point or axis for each revolution, at least some of the spiral shaped flow conduits comprises at least one of sections in series with alternating cross section area for flow and a section with serpentine-type shape for flow along the in substance spiral shaped flow conduits; and wherein the spiral shaped flow conduits have a fluid conduit length of at least 0.2 meter, an inlet operatively coupled to an inner or outer end of the spiral shaped flow conduits, an outlet operatively coupled to the other end of the conduits than the inlet, and a control member.

2. The water injection flow control device according to claim 1, wherein at least some of the in substance spiral shaped flow conduits comprises sections in series with alternating large and small cross section area for flow, wherein a ratio of at least one dimension in the flow conduit transverse to a central flow line through the sections of large and small cross section areas for flow is in a range 1.05-10, most preferably about 2.

3. The water injection flow control device according to claim 1, wherein at least some of the in substance spiral shaped flow conduits comprise a section with serpentine-type shape for flow in the spiral shaped flow conduits, with sections of constant or variable cross section area in serpentine shape along a central flowline of in substance spiral shape, the shape of the serpentine can be as square waves or sinusoidal waves or combinations between, preferably each of a wave periodicity P, the distance between repeated waves, and a wave amplitude A, the distance between top and bottom of the repeated waves, are between 4 and 40 d, wherein P and A are equal or different in any combination, and wherein d is a dimension in the flow conduit transverse to a central flow line along the serpentine-type flow or d is the smallest or a typical conduit cross section diameter.

4. The water injection flow control device according to claim 1, wherein a distance S between alternating sections with large and small cross section area for flow is in a range 1 to 40 d, where d is a dimension in the flow conduit transverse to a central flow line through the sections of small cross section areas for flow, wherein d is at least 0.5 mm, more preferably at least 2 mm.

5. The water injection flow control device according to claim 1 1-4, wherein the device comprises one or more of the following features, in any combination: a stack of discs or cone-like plates with integrated spiral shaped conduits, a stack of discs or cone-like plates having spiral shaped grooves on at least one side, wherein the spiral shaped conduits have been formed by stacking the discs or plates as, and a stack of discs or cone-like plates having a spiral shaped opening punched out or otherwise formed and discs or plates without a spiral shaped opening, wherein the spiral shaped conduits have been formed by alternatingly stacking discs or plates with and without spiral shaped opening.

6. The water injection flow control device according to claim 1, wherein the stack comprises or forms spiral shaped conduits of smaller cross section area for flow towards one end of the stack, arranged so that when the control member chokes the flow through the device the conduits remaining open for flow have smaller cross section area for flow than the conduits closed for flow.

7. The water injection flow control device according to claim 1, wherein the conduit cross section area for flow is enlarged at an inlet and at an outlet for each spiral shaped flow conduit.

8. The water injection flow control device according to claim 1, wherein the number of sections in series of alternating large and small cross section area for flow is at least two, more preferably at least ten.

9. The water injection flow control device according to claim 1, wherein it comprises an outer housing or cover containing the stack, the outer housing or cover is dimensioned to withstand a water injection well wellhead pressure, and the device is dimensioned to choke the pressure up to 50 bar.

10. The water injection flow control device according to claim 1, wherein it comprises a central channel in the stack, connected to an inner end of the spiral shaped conduits, and a peripheral channel, arranged inside the outer periphery of the stacked discs or plates or by an aligned recession in the outer periphery of each stacked disc or plate but inside an outer cover, connected to an outer end of the spiral shaped conduits, and the control member is arranged operatively in at least one of the channels.

11. The water injection flow control device according to claim 1, wherein the sections in series of alternating large and small cross section area for flow are arranged symmetrically about a center line of flow in the spiral shaped conduits, and the transitions between the sections are gradual.

12. The water injection flow control device according to claim 1, wherein each conduit has length in the range 0.2-50 m, and the number of conduits is in the range 2-2000.

13. The water injection flow control device according to claim 1, wherein the cross section area of the conduits in sum equals more than 110% of the cross section area of each of the channels or a nominal area for flow upstream of the device.

14. A water injection system comprising: a water injection pump and a polymer mixing station operatively coupled to a water source, for mixing polymer into the water and pumping the mixture; two or more injection wells operatively connected, one or more injection wells having a lower pressure than a highest pressure injection well, a water injection flow control device operatively arranged for at least each lower pressure well, for adjusting the pressure, the water injection flow control device comprising: a stack of discs or cone-like plates, the discs or cone-like plates as stacked or per se comprises in substance spiral shaped flow conduits, the spiral shaped flow conduits comprises at least one revolution, the spiral shaped flow conduit being turned about a central point or axis and departing or approaching the central point or axis for each revolution, at least some of the spiral shaped flow conduits comprises at least one of sections in series with alternating cross section area for flow and a section with serpentine-type shape for flow along the in substance spiral shaped flow conduits; and wherein the spiral shaped flow conduits have a fluid conduit length of at least 0.2 meter, an inlet operatively coupled to an inner or outer end of the spiral shaped flow conduits, an outlet operatively coupled to the other end of the conduits than the inlet, and a control member.

15. (canceled)

Description

FIGURES

[0060] FIG. 1 illustrates an embodiment of a water injection flow control device of the invention,

[0061] FIG. 2 illustrates sections in series with alternating large and small cross section area for flow in flow conduits in a device of the invention, and

[0062] FIG. 3 illustrates a disc in a water injection flow control device of the invention,

[0063] FIG. 4 illustrates a system for water injection according to the invention,

[0064] FIG. 5 provides some examples on the technical effect of the invention,

[0065] FIGS. 6A-6D illustrate details of some embodiments comprising a serpentine-type conduit in a device of the invention, and

[0066] FIGS. 7A-7C illustrate some of the performance of a device of the invention.

DETAILED DESCRIPTION

[0067] FIG. 1 illustrates a water injection flow control device 1 of the invention. The device comprises a stack 2 of discs 3, the discs as stacked comprises in substance spiral shaped flow conduits 4, said spiral shaped flow conduits comprises sections in series with alternating large and small cross section area for flow 4A, wherein a ratio of at least one dimension in the flow conduit transverse to a central flow line through said sections of large and small cross section areas for flow is in a range 1.05-10. The device comprises an inlet 5, or part thereof, coupled to an inner end of the spiral shaped flow conduits, an annular outlet 6 operatively coupled to an outer end of said conduits, and a control member 7 arranged in the inlet. In addition, the device comprises a housing 8, containing the stack of discs.

[0068] The illustrated embodiment of the device of the invention comprises a stack of discs with a spiral shaped groove on one side of each disc, the other side is flat or plain, the discs as stacked form the spiral shaped conduits between them, along the spiral shaped grooves. Details of the structure are easier to observe in FIGS. 2 and 3.

[0069] FIG. 2 illustrates sections in series with alternating large and small cross section area for flow in flow conduits in a device of the invention, as four detail illustration, each comprising spiral shaped grooves 4G with alternating large 4L and small 4S cross section area for flow in the respective flow conduits as formed by stacking the discs. The depth of the groves is constant, only the width vary between sections with large and small cross section. If said widths are 4L and 4S, respectively, the ratio 4L/4S is in a range 1.05-10. The transition between said alternating sections are gradual, without sharp edges. FIG. 3 illustrates a single disc 3, in a water injection flow control device of the invention, comprising a groove 4G with said alternating sections 4G, 4L. The groove or conduit cross section area for flow is enlarged at an inlet 4I and at an outlet 4O for each spiral shaped flow conduit, by having larger width of the groove or conduit.

[0070] As an alternative to flat discs, cone-like plates can be used in a water injection flow control device of the invention, which can be preferable for high pressure water injection wells, since a longer or equal conduit length at reduced outer diameter thereby is possible.

[0071] FIG. 4 illustrates a system for water injection according to the invention. More specifically, a mother polymer solution is in a static mixer or a similar unit mixed with injection water from a pump 10. The mixture is choked down to a lower pressure in a water injection flow control device 1 of the invention. Parallel arrangements are provided at least for each injection well having lower injection pressure than the highest pressure water injection well.

[0072] FIG. 5 provides some examples on the technical effect of the invention. More specifically, the polymer degradation with a water injection flow control device of the invention is compared to the polymer degradation with an industry standard valve, at identical conditions. While a standard valve results in polymer degradation from about 40% to 60% at choking effect (dP) from about 5 bar to 20 bar, the device of the invention results in polymer degradation from about 2% to 7% at choking effect (dP) from about 5 bar to 20 bar. This has significant effect on the recovery of oil, the oil production rate and the polymer consumption.

[0073] FIGS. 6A illustrates a flow conduit with assymetrical cross section for flow in a device of the invention. FIGS. 6B and 6C illustrate details of conduits with serpentine-type shape for flow along the in substance spiral shaped flow conduit, in a device of the invention. FIG. 6D illustrates details of another embodiment of a serpentine-type conduit in a device of the invention.

[0074] FIGS. 7A-7C illustrate some of the performance of a device of the invention, more specifically with 11 discs in substance as illustrated in FIGS. 2 and 3. In FIG. 7A, the flow rate and differential pressure is illustrated while the control member holds 1, 3, 5, 7, 9 and 11 discs open for flow, respectively. In FIG. 7B, the corresponding flow rate per disc is illustrated, the flow rate per disc is rather constant. In FIG. 7C, the polymer degradation versus pressure loss (DP) is illustrated. The degradation per disc is about identical for a given pressure loss. For a given pressure loss DP, more discs can be coupled inline by operating the control member, for increased flow rate at identical degradation.

[0075] The technical effect of the present invention is surprising, testing and simulations indicate that polymer degradation can be reduced from 60-70% and down to 10-20%, by the new device of the invention and based on calculation of degradation, Deg %, according to the formula:

[00001]$\mathrm{Deg}.Math..Math.\%=\frac{{}_o-{}_{\mathrm{deg}}}{{}_o-{}_{H.Math..Math.2.Math.O}}100$

[0076] Where: [0077] .sub.o=Viscosity of inlet [0078] .sub.deg=Viscosity of sample (degraded) [0079] .sub.H2O=Viscosity for water

[0080] Some test results are even more favorable, as illustrated in FIG. 5.