EP2809877A2

EP2809877A2 - Traversable, segmented wellbore obstructions

Info

Publication number: EP2809877A2
Application number: EP12791345.7A
Authority: EP
Inventors: Peter S. Aronstam; Roger W. Fincher
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-10-31
Filing date: 2012-10-29
Publication date: 2014-12-10
Also published as: WO2013066825A2; WO2013066825A3

Abstract

The present invention generally relates to a traversable wellbore obstruction. In one aspect, an obstruction device for use in a wellbore is provided. The obstruction device includes a housing having a passageway. The obstruction device further includes at least two obstruction members. Each obstruction member includes a first end and a second end. The second end of each obstruction member is pivotably connected to the housing, wherein the obstruction members are movable between a first position in which the passageway of the housing is obstructed, and a second position in which the passageway of the housing is unobstructed. In another aspect, a method of controlling a passageway in a conduit disposed in a wellbore is provided. In a further aspect, a system for use in a wellbore is provided.

Description

TRAVERSABLE, SEGMENTED WELLBORE OBSTRUCTIONS

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] Embodiments of the present invention generally relate to wellbore operations. More specifically, embodiments of the present invention relate to a traversable wellbore obstruction for use in a wellbore operation.

Description of the Related Art

[0002] It has long been practiced to place energy generating equipment in a side pocket mandrel in a tubular disposed in the wellbore. The side pocket mandrel is disposed adjacent a bore of the tubular. As fluid flows through the tubular, a portion of the fluid moves though the energy generating equipment in the side pocket mandrel, and another portion of the fluid moves through the bore of the tubular. The problem with this design is that it is difficult to get the fluid to flow through the side pocket mandrel as that fluid pathway has a higher resistance to fluid flow as compared to the resistance to fluid flow in the bore of the tubular. Several methods have been suggested in the past to compensate for the difference in resistance to fluid flow. For example, obstructions are placed in the path of the flow in the bore of the tubular, or turbulence is created by narrowing the passage way in the bore of the tubular to attempt to force fluid to pass through the side pocket mandrel. Either method causes problems in allowing other tools to pass the restriction in the bore of the tubular during a wellbore operation. Therefore, there is a need for a traversable wellbore obstruction for use in the wellbore operation.

SUMMARY OF THE INVENTION

[0003] The present invention generally relates to a traversable wellbore obstruction. In one aspect, an obstruction device for use in a wellbore is provided. The obstruction device includes a housing having a passageway. The obstruction device further includes at least two obstruction members. Each obstruction member includes a first end and a second end. The second end of each obstruction member is pivotably connected to the housing, wherein the obstruction members are movable between a first position in which the passageway of the housing is obstructed, and a second position in which the passageway of the housing is unobstructed. [0004] In another aspect, a method of controlling a passageway in a conduit disposed in a wellbore is provided. The method includes the step of placing an obstruction device in the conduit, wherein the obstruction device includes a housing with a passageway and a plurality of obstruction members. Each obstruction member includes an end attached to the housing at a pivot point. The method further includes the step of rotating the obstruction members around the pivot point from a first position to a second position to open the passageway in the housing, to allow a tool to move through the passageway. The method also includes the step of rotating the obstruction members around the pivot point from the second position to the first position which causes adjacent edges of the obstruction members to meet to close the passageway in the housing.

[0005] In a further aspect, a system for use in a wellbore is provided. The system includes a power generating unit disposable in a conduit in the wellbore. The power generating unit includes a body with a fluid passageway and an annular turbine. The system further includes an obstruction device attached to the annular turbine. The obstruction device includes a housing with a passageway that is in fluid communication with fluid passageway of the power generating unit. The obstruction device further includes at least two obstruction members. Each obstruction member having an end pivotably connected to the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention, and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0007] Figure 1 is a view illustrating a traversable wellbore obstruction

[0008] Figure 2 is a view illustrating the traversable wellbore obstruction in a first position in which the traversable wellbore obstruction obstructs a fluid passageway. [0009] Figure 3 is a view illustrating the traversable wellbore obstruction in the second position in which the traversable wellbore obstruction opens the fluid passageway.

[0010] Figure 4 is a view illustrating an obstruction member that is used in the traversable wellbore obstruction. [0011] Figure 5 is a view illustrating the traversable wellbore obstruction in an annular turbine alternator.

[0012] Figure 6 is a view illustrating a traversable wellbore obstruction.

[0013] Figure 7 is a view illustrating the traversable wellbore obstruction in a first position in which the traversable wellbore obstruction obstructs the fluid passageway. [0014] Figure 8 is a view illustrating a side of the traversable wellbore obstruction.

[0015] Figures 9A and 9B are views illustrating an obstruction member that is used in the traversable wellbore obstruction.

DETAILED DESCRIPTION

[0016] The present invention generally relates to a traversable wellbore obstruction. The traversable wellbore obstruction will be described herein in relation to an annular turbine alternator that is used in the wellbore. It is to be understood, however, that the traversable wellbore obstruction may also be used with other downhole tools, without departing from principles of the present invention. To better understand the novelty of the traversable wellbore obstruction of the present invention and the methods of use thereof, reference is hereafter made to the accompanying drawings.

[0017] Figure 1 is a view illustrating a traversable wellbore obstruction 40. Generally, the traversable wellbore obstruction 40 is configured to selectively move between a first position in which the traversable wellbore obstruction 40 obstructs a passageway 75 (Figure 2) through a wellbore and a second position in which the traversable wellbore obstruction 40 opens the passageway 75 (Figure 3) to allow a tool 50 to move through the passageway 75. The traversable wellbore obstruction 40 may move between the first position and the second position any number of times. [0018] As shown in Figure 1 , the traversable wellbore obstruction 40 includes obstruction members 30, which cooperate together to obstruct the passageway 75 through the wellbore. The obstruction members 30 may be blades, arms or pedals. Each obstruction member 30 has a first end 35 and a second end 37. The second end 37 of the obstruction member 30 is pivotably attached to a housing 38 of the traversable wellbore obstruction 40 at a pivot point 32. In one embodiment, the second end 37 of the obstruction member 30 is attached to the housing 38 via a pin member. The first end 37 of the obstruction member 30 is able to move relative to the housing 38. The obstruction members 30 may be made from a metal, a plastic or a composite material. In the embodiment shown in Figure 1 , the traversable wellbore obstruction 40 includes seven obstruction members 30. It should be understood, however, that the traversable wellbore obstruction 40 may include any number of obstruction members 30, without departing from principles of the present invention. As shown, the body of each obstruction member 30 is formed in twisted shape and the second end 37 the obstruction member 30 is tapered outward. The exact shape of the obstruction member 30 may be determined by the total number of obstruction members in the traversable wellbore obstruction 40, and in general the shape of the obstruction member 30 is chosen to mate closely with other obstruction members when in the traversable wellbore obstruction 40 is in the first position. The shape of several obstruction members 30 is such that in the normal state the obstruction members 30 arch inward into the passageway 75, and the obstruction members 30 adjacent edges meet to close off a substantial part of the passageway 75. The shape and number of obstruction members 30 also allow for the existence of a central passage (i.e., passageway 75) through the obstruction, which is open. By changing shape and/or number of obstruction members 30 the size of the through hole in the passageway 75 may be changed. This is of particular interest in cases where a wireline tool is passed through the traversable wellbore obstruction 40 when the traversable wellbore obstruction is in the first position. The opening in the passageway 75 allows for passage of the wireline without undue wear of the obstruction members 30. In one embodiment, the obstruction members 30 may be coated with a hard material or include durable inserts, such as tungsten carbide inserts, to reduce wear by passing tools or wireline. [0019] Figure 2 is a view illustrating the traversable wellbore obstruction 40 in the first position. As shown, the passageway 75 is obstructed or blocked by the traversable wellbore obstruction 40. In this position, fluid flow may move through the passageway 75, but the amount of fluid flow is substantially reduced due to the obstruction members 30. In another embodiment, the obstruction members 30 of the traversable wellbore obstruction 40 completely closes (or blocks) the passageway 75 to fluid flow, which results in no fluid flow through the passageway 75. The overlapping obstruction members 20 form an impeller structure within the housing 38. Flow through the traversable wellbore obstruction 40 will cause a rotational torque which can be used to augment the generation of power in the conduit, as will be discussed herein.

[0020] Figure 3 is a view illustrating the traversable wellbore obstruction 40 in the second position. As the tool 50 proceeds through the traversable wellbore obstruction 40, the tool 50 pushes the obstruction members 30 out and causes the traversable wellbore obstruction 40 move to the second position. Each obstruction member 30 pivots around the pivot point 32 and moves into a recess behind the housing 38. The operation of the traversable wellbore obstruction 40 is bidirectional. The tool 50 may move through the traversable wellbore obstruction 40 in a first direction and an opposite second direction. The first direction being defined as a direction from the first end 35 toward the second end 37 of the obstruction members 30, and the second opposite direction being defined as a direction from the second end 37 toward the first end 35 of the obstruction members 30. After the tool has passed through the traversable wellbore obstruction 40, the obstruction members 30 return to their original positions as shown in Figure 2.

[0021] Figure 4 is a view illustrating the obstruction member 30 that is used in the traversable wellbore obstruction 40. As shown, the obstruction member 30 is twisted into an air foil shape. In another embodiment, the obstruction member 30 may be shaped volumetrically and/or in a twisted arrangement to create a lift shape (not shown). The shape of the obstruction member 30 allows the traversable wellbore obstruction 40 to permit the production of rotational torque. As also shown in Figure 4, the first end 35 of the obstruction member 30 has the pivot point 32, which allows the obstruction member 30 to be attached to the housing (not shown). [0022] Figure 5 is a view illustrating the traversable wellbore obstruction 40 in an annular turbine alternator 60. The annular turbine alternator 60 is configured to generate electricity by using fluid moving through a conduit 90. The annular turbine alternator 60 includes a flow passageway 43 that allows fluid to move through the annular turbine alternator 60. The flow passageway 43 may be in fluid communication with the passageway 75. The passageway 75 of the traversable wellbore obstruction 40 and the flow passageway 43 of the annular turbine alternator 60 may also be used to deliver tools beyond the location of the annular turbine alternator 60 in the conduit 90, to perform other wellbore operations, such as valve manipulation, cleaning or fluid treatment.

[0023] The annular turbine alternator 60 is powered by an annular turbine 42. During normal operation fluid flowing in the conduit 90 is split with a first portion of the fluid flowing through the blades of the annular turbine 42, and a second portion of the fluid flowing through the flow passageway 43 in the center of the annular turbine alternator 60. Without the use of the traversable wellbore obstruction 40, flow resistance is greater through the annular turbine 42 than through the flow passageway 43 of the annular turbine alternator 60, as such more fluid will flow though the flow passageway 43 of the annular turbine alternator 60 reducing the power, which can be produced by the annular turbine alternator 60. The use of the traversable wellbore obstruction 40 in the flow passageway 43 causes an increase in the flow resistance in the flow passageway 43. In other words, flow resistance is greater through the flow passageway 43 than through the annular turbine 42. Thus, the first portion of the fluid in the conduit 90 flowing through the blades of the annular turbine 42 is increased as compared to the second portion of fluid in the conduit 90 flowing through the flow passageway 43. As a result, the annular turbine alternator 60 generates more electricity when the traversable wellbore obstruction 40 is used than if the traversable wellbore obstruction 40 was not used.

[0024] It is also possible to further increase the power generated by the annular turbine alternator 60 by using the traversable wellbore obstruction 40, because the traversable wellbore obstruction 40 includes the shaped or twisted obstruction members 30. As set forth herein, the obstruction members 30 are twisted into an air foil shape, which permit the production of rotational torque as fluid flows through the conduit 90. The traversable wellbore obstruction 40 is attached to the blades of the annular turbine 42. The additional power generated by the obstruction members 30 add to the power which is developed by the annular turbine 42, thus the traversable wellbore obstruction 40 acts as a second impeller. [0025] By selecting the dimensions of the obstruction members 30 and the shape of the obstruction members 30, it is possible to control the amount of fluid which passes through the annular turbine 42 (e.g., first portion of fluid), versus the flow passageway 43 (e.g., second portion of fluid). This allows the user to change the flow/power generation ratio to tune the complete system for conduits of different flow rates. [0026] Figure 6 is a view illustrating a traversable wellbore obstruction 10. The traversable wellbore obstruction 10 is configured to selectively move between a first position in which the traversable wellbore obstruction 10 obstructs the passageway through the wellbore and a second position in which the traversable wellbore obstruction 10 opens the passageway to allow a tool to move through the traversable wellbore obstruction 10. The traversable wellbore obstruction 10 may move between the first position and the second position any number of times.

[0027] As shown in Figure 6, the traversable wellbore obstruction 10 includes obstruction members 20, which cooperate together to obstruct the passageway 75 through the wellbore. The obstruction members 20 may be blades, arms or pedals. Each obstruction member 20 has a first end 25 and a second end 27. The second end 27 of the obstruction member 20 is pivotably attached to a housing 28 of the traversable wellbore obstruction 10 at a pivot point 22. In one embodiment, the second end 27 of the obstruction member 20 is attached to the housing 28 via a pin member. The obstruction members 20 are affixed to the housing 28 such that the obstruction members 20 bow inward into the flow passage forming the obstruction. The design shape of the obstruction members 20 is such that the adjacent edges of the obstruction members 20 meet to occlude the passageway. The first end 27 of the obstruction member 20 is able to move relative to the housing 28. The obstruction members 20 may be made from a metal, a plastic or a composite material. [0028] In the embodiment shown in Figure 6, the traversable wellbore obstruction 10 includes seven obstruction members 20. It should be understood, however, that the traversable wellbore obstruction 10 may include any number of obstruction members 20, without departing from principles of the present invention. As shown, the body of each obstruction member 20 is formed in an arcuate shape and tapered in the center. The exact shape of the obstruction member 20 is determined by the total number of obstruction members 20 in the traversable wellbore obstruction 10, and in general is chosen to mate closely with other obstruction members 20 when in the traversable wellbore obstruction 10 is in the first position. The shape of the several obstruction members 20 is such that in the normal state the obstruction members 20 arch inward into the passageway, and the obstruction members 20 adjacent edges meet to close off a substantial part of the passageway. The shape and number of obstruction members 20 also allow for the existence of a central passage (i.e., passageway 75) through the traversable wellbore obstruction 10 which is open. By changing shape and/or number of obstruction members 20 the size of the through hole in the passageway 75 may be changed. This is of particular interest is cases where a wireline tool is passed through the traversable wellbore obstruction 10, when the traversable wellbore obstruction is in the first position. The opening in the passageway allows for passage of the wireline without undue wear of the obstruction members 20. In one embodiment, the obstruction members 20 may be coated with a hard material or include durable inserts, such as tungsten carbide inserts, to reduce wear by passing tools or wireline. [0029] Figure 7 is a view illustrating the traversable wellbore obstruction 10 in the first position. As shown, the passageway 75 is obstructed or blocked by the traversable wellbore obstruction 10. In this position, fluid flow may move through the passageway 75, but the amount fluid flow is substantially reduced due to the obstruction members 20. In another embodiment, the obstruction members 20 of the traversable wellbore obstruction 10 completely closes (or blocks) the passageway 75 to fluid flow, which results in no fluid flow through the passageway 75. As set forth herein, the traversable wellbore obstruction 10 is able to move to the second position (not shown) in which the traversable wellbore obstruction 10 opens the passageway 75 to allow a tool (not shown) to move through the traversable wellbore obstruction 10. As the tool proceeds through the traversable wellbore obstruction 10, the tool pushes the obstruction members 20 out of its way, which causes the traversable wellbore obstruction 10 to move to the second position. Each obstruction member 20 pivots around the pivot point 22 and moves into a recess behind the housing 28. The operation of the traversable wellbore obstruction 10 is bidirectional. The tool may move through the traversable wellbore obstruction 10 in a first direction and an opposite second direction. The first direction being defined as a direction from the first end 25 toward the second end 27 of the obstruction members 20, and the second opposite direction being defined as a direction from the second end 27 toward the first end 25 of the obstruction members 20. After the tool has passed through the traversable wellbore obstruction 10, the obstruction members 20 return to their original positions as shown in Figure 7.

[0030] The traversable wellbore obstruction 10 may be attached to an annular turbine alternator in a similar manner as the traversable wellbore obstruction 40. The flow passageway in the annular turbine alternator may be in fluid communication with the passageway 75. The passageway 75 of the traversable wellbore obstruction 10 and the flow passageway of the annular turbine alternator may also be used to deliver tools beyond the location of the annular turbine alternator in the conduit to perform other wellbore operations, such as valve manipulation, cleaning or fluid treatment. [0031] The use of the traversable wellbore obstruction 10 in the flow passageway of the annular turbine alternator causes an increase in the flow resistance in the flow passageway. In other words, flow resistance is greater through the flow passageway than through the annular turbine. Thus, the first portion of the fluid in the conduit flowing through the blades of the annular turbine is increased as compared to the second portion of fluid of the conduit flowing through the flow passageway. As a result, the annular turbine alternator generates more electricity when the traversable wellbore obstruction 10 is used, than if the traversable wellbore obstruction 10 was not used. By selecting the dimensions of the obstruction members 20 and the shape of the obstruction members 20, it is possible to control the amount of fluid which passes through the annular turbine (e.g., first portion of fluid) versus the flow passageway (e.g., second portion of fluid). This allows the user to change the flow/power generation ratio to tune the complete system for conduits of different flow rates.

[0032] Figure 8 is a view illustrating a side of the traversable wellbore obstruction 10. The nature of the fit between adjacent obstruction members 20 can be seen. The traversable wellbore obstruction 10 is in the first position in which the traversable wellbore obstruction 10 obstructs the passageway, and only a slight passage way formed by the contact of the adjacent obstruction members 20. As set forth herein, the obstruction members 20 are connected to the housing 28 by pins running through pivot points 22. A tool (not shown), proceeding through the traversable wellbore obstruction 10 deforms the obstruction members 20, forcing the obstruction members 20 to bow outwards, opening the passage through the traversable wellbore obstruction 10. Once the tool is past the traversable wellbore obstruction 10, the obstruction members 20 spring back to their original shape whereby obstructing the passageway again.

[0033] Figures 9A and 9B are views illustrating the obstruction member 20 that is used in the traversable wellbore obstruction 10. As shown, the obstruction member 20 is formed in an arcuate shape and tapered in the center. As also shown, the first end 25 of the obstruction member 20 has the pivot point 22 which allows the obstruction member 20 to be attached to the housing (not shown).

[0034] In one embodiment, a traversable borehole obstruction is provided which can be temporarily deformed by a passing tool from either direction. In an embodiment, the temporarily deformable obstruction is formed by a series of inward facing petals or arms, which are free to pivot from one end. A passing tool from either end simply pushes the arms back against the borehole wall allowing passage. After tool passage, the arms return to their original shape effectively blocking the passageway. In another embodiment, the arms of the obstruction can be twisted or shaped to create rotational forces which may be of value in the application of such devices with annular turbines. In such application the device is affixed within the turbine structure, acting as a second set of turbine blades.

[0035] In one embodiment, an obstruction device for use in a wellbore is provided. The obstruction device includes a housing having a passageway. The obstruction device further includes at least two obstruction members. Each obstruction member includes a first end and a second end. The second end of each obstruction member is pivotably connected to the housing, wherein the obstruction members are movable between a first position in which the passageway of the housing is obstructed, and a second position in which the passageway of the housing is unobstructed.

[0036] In one or more embodiments, the passageway in the housing has a first diameter when the obstruction members are in the first position and a second larger diameter when the obstruction members are in the second position. [0037] In one or more embodiments, a tool moving through the passageway of the housing causes the obstruction members to move from the first position to the second position.

[0038] In one or more embodiments, the obstruction members are configured to move from the second position to the first position after the tool moves through the passageway.

[0039] In one or more embodiments, the obstruction members are configured to allow a tool to move through the passageway of the housing when the obstruction members are in the second position. [0040] In one or more embodiments, the obstruction members are configured to allow a tool to move through the passageway of the housing when the obstruction members are in the first position.

[0041] In one or more embodiments, the obstruction members are configured to close the passageway of the housing when the obstruction members are in the first position. [0042] In one or more embodiments, the shape of the obstruction members is selected to change the pressure of the fluid flowing into the passageway of the housing.

[0043] In one or more embodiments, the obstruction members are configured to allow generation of a rotational force as fluid flows through the obstruction members.

[0044] In one or more embodiments, the obstruction members are armored to prevent wear during passage of tools through the obstruction members.

[0045] In one embodiment, a method of controlling a passageway in a conduit disposed in a wellbore is provided. The method includes the step of placing an obstruction device in the conduit, wherein the obstruction device includes a housing with a passageway and a plurality of obstruction members. Each obstruction member includes an end attached to the housing at a pivot point. The method further includes the step of rotating the obstruction members around the pivot point from a first position to a second position, to open the passageway in the housing to allow a tool to move through the passageway. The method also includes the step of rotating the obstruction members around the pivot point from the second position to the first position which causes adjacent edges of the obstruction members to meet to close the passageway in the housing.

[0046] In one embodiment, a system for use in a wellbore is provided. The system includes a power generating unit disposable in a conduit in the wellbore. The power generating unit includes a body with a fluid passageway and an annular turbine. The system further includes an obstruction device attached to the annular turbine. The obstruction device includes a housing with a passageway that is in fluid communication with fluid passageway of the power generating unit. The obstruction device further includes at least two obstruction members. Each obstruction member having an end pivotably connected to the housing.

[0047] In one or more embodiments, the obstruction members are configured to generate a rotational force as fluid flows through the conduit.

[0048] In one or more embodiments, the rotational force of the obstruction device is used to augment the rotational force used by the annular turbine to generate power. [0049] In one or more embodiments, the dimensions and shape of the obstruction member is used to change the Delta Pressure through the passageway.

[0050] In one or more embodiments, the strength of material selected for the obstruction member is chosen to regulate the extent that flowing fluid opens the passageway. [0051] In one or more embodiments, adjacent edges of the obstruction members meet to close the passageway in the housing when the obstruction members are in the second position.

[0052] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:

1 . An obstruction device for use in a wellbore, the device comprising:

a housing having a passageway; and

at least two obstruction members, each obstruction member having a first end and a second end, the second end being pivotably connected to the housing, wherein the obstruction members are movable between a first position in which the passageway of the housing is obstructed and a second position in which the passageway of the housing is unobstructed.

2. The device of claim 1 , wherein the passageway in the housing has a first diameter when the obstruction members are in the first position and a second larger diameter when the obstruction members are in the second position.

3. The device of claim 1 , wherein a tool moving through the passageway of the housing causes the obstruction members to move from the first position to the second position.

4. The device of claim 3, wherein the obstruction members are configured to move from the second position to the first position after the tool moves through the passageway.

5. The device of claim 1 , wherein the obstruction members are configured to allow a tool to move through the passageway of the housing when the obstruction members are in the second position.

6. The device of claim 1 , wherein the obstruction members are configured to allow a tool to move through the passageway of the housing when the obstruction members are in the first position.

7. The device of claim 1 , wherein the obstruction members are configured to close the passageway of the housing when the obstruction members are in the first position.

8. The device of claim 1 , wherein adjacent edges of the obstruction members meet to close the passageway in the housing when the obstruction members are in the second position.

9. The device of claim 1 , wherein the obstruction members are configured to allow generation of a rotational force as fluid flows through the obstruction members.

10. The device of claim 1 , wherein the obstruction members are armored to prevent wear during passage of tools through the obstruction members.

1 1 . A method of controlling a passageway in a conduit disposed in a wellbore, the method comprising:

placing an obstruction device in the conduit, wherein the obstruction device includes a housing with a passageway and a plurality of obstruction members, each obstruction member having an end attached to the housing at a pivot point;

rotating the obstruction members around the pivot point from a first position to a second position to open the passageway in the housing to allow a tool to move through the passageway; and

rotating the obstruction members around the pivot point from the second position to the first position which causes adjacent edges of the obstruction members to meet to close the passageway in the housing.

12. The method of claim 1 1 , wherein the tool moving through the passageway of the housing causes the obstruction members to move from the first position to the second position.

13. The method of claim 1 1 , wherein the obstruction members are configured to allow a tool to move through the passageway of the housing when the obstruction members are in the first position.

14. The method of claim 1 1 , wherein the passageway in the housing has a first diameter when the obstruction members are in the first position and a second larger diameter when the obstruction members are in the second position.

15. A system for use in a wellbore, the system comprising:

a power generating unit disposable in a conduit in the wellbore, the power generating unit having a body with a fluid passageway and an annular turbine; and

an obstruction device attached to the annular turbine, the obstruction device having a housing with a passageway that is in fluid communication with fluid passageway of the power generating unit, and at least two obstruction members, each obstruction member having an end pivotably connected to the housing.

16. The system of claim 15, wherein the obstruction members are configured to generate a rotational force as fluid flows through the conduit.

17. The system of claim 16, wherein the rotational force of the obstruction device is used to augment the rotational force used by the annular turbine to generate power.

18. The system of claim 15, wherein the obstruction members are movable between a first position in which the passageway of the housing is obstructed and a second position in which the passageway of the housing is unobstructed.

19. The system of claim 18, wherein a tool moving through the passageway of the housing causes the obstruction members to move from the first position to the second position.

20. The system of claim 19, wherein the obstruction members are configured to move from the second position to the first position after the tool moves through the passageway.