FILAMENTOUS MEMBER INJECTOR AND METHOD FOR INJECTING FILAMENTOUS MEMBERS

Abstract

A filamentous member injection device including a housing; a capstan drivably disposable in the housing; a restricted diameter tubular extending from the housing and being in fluid communication with an interior of the housing. A method for injecting a filamentous member into a target tubular includes wrapping the filamentous member about a capstan; causing a tensile force to be placed on a portion of the filamentous member downstream of the capstan, the tensile force acting on the capstan; binding the filamentous member to the capstan; and driving the filamentous member into the target tubular with the capstan.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional application 60/844,021 filed Sep. 12, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND

Filamentous members such as optic fibers are extremely useful in signal transmission and sensing in many industries. One such industry is the hydrocarbon exploration and production industry. Optic fibers provide great advantages over other methods of transmitting signals or sensing parameters downhole. Due to the very long distances over which fibers must be laid, however, and the difficulty presented by collisions of tools with the casing of a wellbore while tripping therethrough, effectively delivering fibers to target locations remains an elusive goal.

One method for installing optical fibers was developed by the telecom industry and involves utilizing viscous drag of a fluid on a fiber to distribute the pulling load along the length of the fiber. This method is capable of “blowing” the fiber into a propositioned conduit and is effective in moving the fiber over relatively long distances. In order to create the flow, however, a pressure gradient is necessarily required between an origin point and a target area. The magnitude of pressure differential is proportional to the length of the tube through which the fiber is to be installed and the cross sectional area of that tube. Because in the oil field, the lengths are upwards of 35,000 ft, the pressure differential required is very high. One example will utilize an origin pressure of 5700 psi to move 0.15 gallons of water through 35,000 ft of 0.250 inch outside diameter×0.152 inch inside diameter tubing. At such pressures a significant problem with blowing fiber becomes evident. That is that the pressure will act on the cross sectional area of the selected fiber to eject the fiber from the tubing if it is not being forced to move into the tube.

A method and apparatus for injecting fiber that overcomes the stated drawback will be well received by the art.

SUMMARY

A filamentous member injection device including a housing; a capstan drivably disposable in the housing; a restricted diameter tubular extending from the housing and being in fluid communication with an interior of the housing.

A method for injecting a filamentous member into a target tubular includes wrapping the filamentous member about a capstan; causing a tensile force to be placed on a portion of the filamentous member downstream of the capstan, the tensile force acting on the capstan; binding the filamentous member to the capstan; and driving the filamentous member into the target tubular with the capstan.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an elevation view of one embodiment of the invention illustrated partially in cross section; and

FIG. 2 is a perspective explodes view of a similar embodiment of the invention.

DETAILED DESCRIPTION

Referring to the figure an embodiment of a filamentous member injector 10 is illustrated. Injector 10 includes a housing 12 comprising a base 14 and a cover 16. The base and cover are pressure sealably connectable to one another to create a pressure vessel so that pressure within the housing can be set above or equal to that of the tubular in which the filamentous member (genus) is to be deployed. The filamentous member may be of any type and for convenience is hereinafter referred to as “fiber” (species) without intending to limit the application of the invention. In the illustration, the cover is retained to the base by a plurality of threaded fasteners such as bolts but it is to be understood that alternative arrangements such as threading the cover directly to the base or utilizing latches or the like is equally applicable. The housing 12 includes a fluid inlet 18, a fiber inlet 20 and a fluid/fiber outlet 22. Fluid outlet 22 is connectable to a short length tubular 24 through which a fiber 26 is to be urged for deployment to a target tubular (not shown). The short length tubular 24 is of narrow inside dimension (restricted diameter) so that fluid flowing therein flows more quickly thereby generating a greater fluid drag on fiber 26. This is helpful at a start of a run to aid in getting the fiber introduced far enough into the system that the fluid drag force is greater than the blowback force. In order to use a short length of the tubular 24 however, instead of a much longer length, which longer length would be necessary to actually balance the fluid drag force with the blowback force, an additional insertion force is required. A method and apparatus to apply such insertion force is taught in this disclosure.

As disclosed herein a mechanical force is applied to the fiber to achieve the desired total force on the fiber to prevent blow back from occurring. Within the housing 12 is a capstan 28. Capstan 28 is driven by a drive 30, which in one embodiment may be a belt drive as illustrated. A belt 32 may be driven by any applicable drive system such as a motor. As in the case with all capstan devices, the drive is rotary causing the capstan to spin on its axis. In addition to the capstan 28, a spiral guide 34 is provided, to operably communicate with the fiber 26 relative to the capstan 28 and which is affixed to the housing 12 in such a way that the spiral guide 34 does not spin with the capstan but remains in close proximity to a surface of the capstan 28. The guide 34 itself has for its purpose to reduce the possibility of the fiber 26 becoming entangled due to the plurality of wraps the fiber makes around the capstan 28 in addition to causing the fiber to engage the capstan at one axial end and to leave the capstan and another axial end as shown. By providing a spiral (or helical) pathway such as a grove, or such as structures defining a groove, the fiber 26 may be guided as noted. The guide 34 is best appreciated with reference to FIG. 2 where it is exploded out of the housing. The guide 34 can be seen in this embodiment to comprise a tubular support 36 having a spiral 38 disposed therein. Spiral 38 is open to the inside dimension thereof to provide access by the fiber situated therein to the surface of the capstan 28 so that motive force may be applied to the fiber 26 when desired. A fiber exit hole 40 can be seen in the guide 34, which allows the fiber 26 to pass into the fluid/fiber outlet 22. A similar fiber inlet hole 42 is illustrated in the guide 34. This hole allows fiber entrance to the guide 34 to be wrapped around capstan 28. the guide 34 as noted is not intended to rotate relative to the housing 12 and thus will include features to prevent such rotation. These may be pins 44 as shown which depend from the support 36 and are received in recesses in the housing (not shown) to prevent relative rotation, or may be an o-ring (not shown) disposed around the support 36 and received in interfering fit with the housing 12, or any other means to prevent relative rotation. The fiber 26 in operable communication with the guide 34 tracks around the capstan 28 in the helical groove of the spiral guide 34 before it exits the guide 34 though hole 40 and exits the housing 12, along with pressurized fluid through fiber and fluid outlet 22.

It should be noted that fluid inlet 18 can be utilized for any fluid medium whether it be liquid or gas, for example, water or air. The pressurization of housing 12 allows for equalization across outlet 22 with the higher-pressure environment of a tubular through which the fiber is to be deployed. As was noted above, the pressure in tubular 24 beyond outlet 22 is significant. In one application, pressure is at 5700 psi. This much pressure makes introduction of fiber 26 difficult as the pressure itself acts upon the cross sectional area of the fiber to push it back out of tubular 24, thus the need for mechanical injection. A corollary however is that a compressive force on an optic fiber, for example, along an axis thereof, is not well tolerated by the fiber. Damage to the fiber is relatively certain with relatively small compressive axial loads thereon. In accordance with this disclosure however, such compressive load is avoided while injection force is maintained.

The Capstan drive will impart a drive force to the fiber 26 only if there is a physical tension on the fiber 26 from the downstream end of the housing 12 from, for example tubular 24. Such a force causes the fiber to bind against the capstan 28 thereby enabling the capstan to drive the fiber. If there is no tensile force on fiber 26, the capstan will merely spin within the coil of fiber created by the several passes of the fiber around the capstan 28. As such the insertion force on the fiber presented by the capstan is very gentle. If by chance the fiber is impeded in its forward motion, even by only a small amount, the necessary tensile force on the fiber will diminish and the capstan will naturally cease driving the fiber. Thereby the fiber is not damaged by any condition where deployment is hindered. In one embodiment, it is the fluid drag force on the fiber alone that provides sufficient tensile force thereon to activate the capstan drive.

In one embodiment of the device disclosed herein, the capstan 28 is removable from the housing 12 to facilitate easy manual wrapping of fiber 26 therearound. The fiber once wrapped around the capstan 28 is fed completely through short tubular 24. The capstan is then deposited within housing 12 in such a way as to engage the drive. This can be by way a gear mesh or any other convenient connection. Once the capstan is properly wound with fiber and returned to housing base 14, the cover 16 is pressure-sealingly secured to base 14 thereby creating pressure sealed housing 12. A target tubular is connected to short tubular 24 by any conventional means and the motor drive is activated to spin the capstan. As noted above, without a tensile force on the fiber 26, the fiber is not bound to the capstan and no mechanical drive force is coupled to the fiber. Rather, the capstan spins harmlessly within the spiral wrap of the fiber until fluid is supplied under pressure to fluid inlet 20. Application of fluid pressure to fluid inlet 20 causes a flow to begin through the fluid and fiber outlet 22. As flow is increased, fluid drag on the segment of the fiber 26 within short tubular 24 begins to pull on the fiber. When the fluid drag builds to a sufficient level to create a tensile force on the fiber, the fiber becomes bound to the capstan thereby allowing the capstan to impart a mechanical injection force to the fiber. Injection of the fiber will continue until a desired depth is reached, flow is stopped or reduced below the bind threshold, the fiber is mechanically impeded in some way or any other force stops or slows injection at which time the fiber will cease providing the requisite tensile force on the capstan to bind itself thereto and the capstan will harmlessly spin within the fiber spiral wrapped around the capstan.

While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.

Claims

1. A filamentous member injection device comprising:

a housing;

a capstan drivably disposable in the housing;

a restricted diameter tubular extending from the housing and being in fluid communication with an interior of the housing.

2. The injection device as claimed in claim 1 wherein the housing is a pressure vessel.

3. The injection device as claimed in claim 1 wherein the capstan further includes a spiral guide fixedly attached to the housing.

4. The injection device as claimed in claim 1 wherein the capstan is in operable communication with a motor.

5. The injection device as claimed in claim 1 wherein the restricted diameter tubular has a diameter calculated to enhance a fluid drag force upon a filamentous member disposed therein.

6. The injection device as claimed in claim 1 wherein the housing further includes a filamentous member inlet and fluid inlet.

7. The injection device as claimed in claim 3 wherein the spiral guide is receptive of the filamentous member to both guide the member from one axial end of the capstan to the other and to avoid entanglement of the filamentous member.

8. The injection device as claimed in claim 3 wherein the spiral guide is a member having a helical groove therein.

9. The injection device as claimed in claim 3 wherein the spiral guide is a helical spring.

10. A method for injecting a filamentous member into a target tubular comprising:

wrapping the filamentous member about a capstan;

causing a tensile force to be placed on a portion of the filamentous member downstream of the capstan, the tensile force acting on the capstan;

binding the filamentous member to the capstan; and

driving the filamentous member into the target tubular with the capstan.

11. The method for injecting a filamentous member as claimed in claim 10 wherein the method further comprises feeding the filamentous member into a restricted diameter tubular.

12. The method for injecting a filamentous member as claimed in claim 10 wherein the method further comprises creating a fluid drag on the filamentous member within a restricted diameter tubular.

13. The method for injecting a filamentous member as claimed in claim 10 wherein the causing is by flowing a fluid through a restricted diameter tubular through which the filamentous member extends.

14. The method for injecting a filamentous member as claimed in claim 10 wherein the binding is by causing sufficient friction between the filamentous member and the capstan to allow the capstan to drive the filamentous member.

15. The method for injecting a filamentous member as claimed in claim 10 wherein the wrapping is spirally wrapping.

16. The method for injecting a filamentous member as claimed in claim 10 wherein the fluid flows through a restricted diameter tubular prior to entering the target tubular.

17. The method for injecting a filamentous member as claimed in claim 16 wherein the fluid flows through a restricted diameter tubular prior to entering the target tubular.

18. The method for injecting a filamentous member as claimed in claim 16 wherein the flowing fluid couples to the filamentous member providing fluid drag thereto along an entirety of the target tubular.

19. The method for injecting a filamentous member as claimed in claim 10 wherein the driving is by activating a motor in operable communication with the capstan.