WO2017116965A1

WO2017116965A1 - Use of fiber carrier to provide optical fiber in a wellbore

Info

Publication number: WO2017116965A1
Application number: PCT/US2016/068248
Authority: WO
Inventors: Dhruv Arora; Matheus Norbertus Baaijens; Stephen Palmer Hirshblond
Original assignee: Shell Oil Company; Shell Internationale Research Maatschappij B.V.
Priority date: 2015-12-28
Filing date: 2016-12-22
Publication date: 2017-07-06

Abstract

A method of providing optical fiber in a wellbore including attaching an upper portion of the fiber along a production tubing and lowering the production tubing into the wellbore. The method may also include attaching a lower portion of the fiber to a fiber carrier and lowering the carrier through the production tubing. Additionally, the method may include attaching a proximal end of the carrier to a distal end of the production tubing. A device for providing optical fiber in a wellbore including a fiber carrier configured to pass through production tubing and a lower portion of the fiber attached to the carrier. The carrier may have a proximal end configured to attach to a distal end of the production tubing such that the lower portion is in optical communication with an upper portion of the fiber present along the production tubing.

Description

USE OF FIBER CARRIER TO PROVIDE OPTICAL FIBER IN A WELLBORE

TECHNICAL FIELD

[0001] This disclosure relates to a method of providing optical fiber in a wellbore. In particular to the use of a fiber carrier to provide a portion of the optical fiber in a completed wellbore.

BACKGROUND

[0002] Sensors in subterranean wells can provide valuable information on the changes in the downhole environment either continuously or periodically, particularly in oil and gas wellbores. However, one of the challenges is the transmission of information between the sensors and the surface. Downhole fiber optics monitoring is universally accepted in the upstream industry as the technology of choice to elucidate flow processes in wellbore production or injection. Using optical fiber to monitor is now seriously considered for new completions due to advances in fiber development and cable manufacturing and the corresponding reduction in manufacturing cost and improvements in processing and visualization algorithms, etc.

[0003] Referring to FIG. 1, conventionally, a cable containing one or more optical fibers 5 for observation of parameters relating to production is attached to an exterior of a casing 10 with clamps and other mechanical devices to transmit information from the sensors to the surface 15. The casing 10 with the cable attached thereto is lowered into the wellbore and secured in place with cement 20. Some believe that the large cable, the clamps, or a combination cause the cement quality in the region of the optical fiber 5 to be

compromised. In other words, the size of the cables used and the mechanical fixation methods limit the applicability of the installation.

[0004] Generally it has not been considered appropriate to attach elongated objects of a significant diameter to the casing 10 in the cement path because there is a risk that there will be insufficient penetration of cement in the interstices between the casing and object and between the object and the wellbore wall, which would therefore result in a leak path from formation to the surface. In turn, such a path is a risk to the integrity of the isolation from formation to surface and thus unacceptable on environmental and safety grounds.

[0005] Another challenge is that wellbore environments may have extreme conditions in terms of e.g. pressure, temperature, pH, or chemical environment. This has limited the possibility to attach sensors to the outer surface of a pipe without using clamps, as the attaching mechanism must first resist such extreme conditions and then have enough flexibility to follow the axial and circumferential geometry of the pipe.

[0006] Several clamp or clampless methods have been devised in the past that attempt to reduce the overall diameter/profile requirement, e.g., U.S. 8942529, U.S. 9187963, and U.S. 7740078. However, as with previous methods, the proposed solutions result in impracticality of replacement of damaged optical fiber 5. Furthermore, this and other known methods do not allow for effective gathering of distributed data from perforated or completed wells.

[0007] Other proposed solutions involve lowering the optical fiber 5 on a production tubing that goes past perforations. However, such methods can cause the production tubing to get stuck or can result in the perforations not having free communication with the wellbore, or both.

[0008] Other challenges pertaining to deployment of optical fibers may negate many of the possible advantages. For example, production downtime, requirements for talent and resources, reliability of the deployed fiber, possibilities of false positives due to faulty deployment, and the like can result in the benefits outweighing the costs.

[0009] The object of the invention is to overcome the limitations of the previous methods using a fiber carrier to provide a portion of the optical fiber in the wellbore.

SUMMARY

[0010] A method of providing optical fiber in a wellbore may include attaching an upper portion of the optical fiber along a production tubing (e.g., along an exterior thereof) and lowering the production tubing into the wellbore. The method may also include attaching a lower portion of the optical fiber to a fiber carrier and lowering the fiber carrier through the production tubing. Additionally, the method may include attaching a proximal end of the fiber carrier to a distal end of the production tubing.

[0011] Another method of providing optical fiber in a wellbore may include providing a production tubing in the wellbore with an upper portion of the optical fiber along the production tubing (e.g., along the exterior) and attaching a lower portion of the optical fiber to a fiber carrier. The method may also include lowering the fiber carrier through the production tubing and attaching a proximal end of the fiber carrier to a distal end of the production tubing. [0012] A device for providing optical fiber in a wellbore may include a fiber carrier configured to pass through production tubing and a lower portion of the optical fiber attached to the fiber carrier. The fiber carrier may have a proximal end configured to attach to a distal end of the production tubing such that the lower portion is in optical

communication with an upper portion of the optical fiber present along the production tubing (e.g., along the exterior).

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention will now be described by way of example with reference to the accompanying drawings, wherein

[0014] FIG. 1 shows a prior art cross sectional view of an optical fiber cemented in a wellbore.

[0015] FIGs. 2-A through 2-C show a cross sectional view of steps as an optical fiber is placed in a wellbore in accordance with some embodiments described below.

[0016] FIGs. 3-A through 3-C shows an alternative to FIGs. 2-A through 2-C, where an upper portion of optical fiber is provided on an interior of a production tubing.

[0017] FIG. 4 shows a connector for connecting or splicing an upper portion of an optical fiber with a lower portion of an optical fiber.

DETAILED DESCRIPTION

[0018] In one method, an optical fiber may be provided in a wellbore through use of a fiber carrier. For example, referring to FIGs. 2-A through 2-C, the optical fiber 5 (generally shown as upper portion 5a and lower portion 5b) is provided in the wellbore 25 by attaching the upper portion 5a along an exterior of a production tubing 30. The production tubing 30 is then lowered into the wellbore 25 as shown in FIG. 2-A. The lower portion 5b is attached to the fiber carrier 35 and the fiber carrier 35 is lowered through the production tubing 30 as shown in FIG. 2-B. A proximal end 40 of the fiber carrier 35 is then attached to a distal end 45 of the production tubing 30 as shown in FIG. 2-C.

[0019] In some instances, it may be desirable to repeat or execute only a portion of the operation. For instance, if the lower portion 5b is damaged, a new lower portion might be used as a replacement. In such circumstances, the method may not require the production tubing 30 to be pulled, but instead may generally only involve disconnection of the damaged or absent lower portion 5b and introduction of the replacement or new lower portion 5b. Thus, the steps might be very similar to the steps described above but without the need to lower the production tubing into the wellbore 25.

[0020] Attaching the lower portion 5b to the fiber carrier 35 may involve strapping, clamping, gluing, taping, or any other method of attaching optical fiber to another object. Thus, the optical fiber 5 may be an integral part of a fabric that may stick by itself or be pasted to an interior diameter of the wellbore 25. The lowering of the fiber carrier 35 may be accomplished via wireline or other methods commonly used to run tools and components into wellbores. In some instances, the lower portion 5b may removably attach to the carrier 35 such that the carrier 35 is retrieved and the lower portion 5b remains in the wellbore 25. For example, the lower portion 5b may be attached to the carrier 35 via releasable clamps or other mechanisms that can be remotely actuated to cause

disengagement. In such example, the carrier 35 may be moved into a position such that magnets or other mechanisms in place in the wellbore 25 engage the lower portion 5b and the appropriate mechanism may be actuated to allow the carrier 35 to be removed.

Similarly, centralizers or other mechanisms may be added to cause the carrier 35 to move into a position that does not obstruct other operations.

[0021] In instances where the upper portion 5a and the lower portion 5b are distinct segments of fiber, the method may further include connecting or splicing the upper portion 5a and the lower portion 5b such that the optical fiber 5 formed by the segments can convey signals from its distal end 50 to its proximal end 55.

[0022] Referring now to FIGs. 3-A through 3-C, the upper portion 5a of the optical fiber 5 may be provided partially or completely on the interior of the production tubing 30.

However, the methods of providing the lower portion 5b would work substantially the same as described above. Thus, for the sake of brevity, it is not described in detail here.

[0023] Referring now to FIG. 4, in some instances, a guide shoe, collar, or other connector 60 may assist in the attachment. Such connector 60 may attach to the distal end 45 of the production tubing 30 and provide a port 65 to accept the proximal end 40 of the fiber carrier 35. The connector 60 may be permanent (e.g., a box attached to the pin of the lowermost joint, when the production tubing 30 is of a joint type) or retrievable (e.g., run in after the production tubing 30 is placed). The connector 60 may include a latching mechanism (not shown) to engage the production tubing 30 and/or the fiber carrier 35. Similarly, the connector 60 may provide any necessary splice in the optical fiber 5 (e.g., via splice window 120) [0024] A device for providing the optical fiber in the wellbore 25 may include the connector 60 described above or similar joining devices. The connector 60 may be configured to provide optical communication between a distal end of the upper portion 5a of the optical fiber and a proximal end of a lower portion 5b of the optical fiber, for example, via splice window 120 illustrated in FIG. 4.

[0025] The fiber carrier 35 may have any of a number of configurations as long as it is rigid enough to convey the lower portion 5b into place and flexible enough to be conveyed through the wellbore 25. The fiber carrier 35 is configured to pass through the production tubing 30. A device for providing optical fiber 5 in the wellbore 25 may thus include the fiber carrier 35 and the lower portion 5b attached to the fiber carrier 35 (e.g., along an axis thereof). The fiber carrier 35 has the proximal end 40 configured to attach to the distal end 45 of the production tubing such that the lower portion 5b is in optical communication with the upper portion 5a which is present along the exterior of the production tubing 30, or which may be later installed.

[0026] For example, the fiber carrier 35 may be an elongated rigid body such as a small- diameter flexible yet resilient member. In such configurations, the lower portion 5b may be placed proximate perforations 75 simply by securing the fiber carrier 35 to the production tubing 30. Notably, the cross section need not be limited to a circular configuration and other cross sectional shapes may provide advantages over this example. One exemplary fiber carrier 35 is a fiberglass whip rod with configurations such as those available from AOFU FIBERGLASS SERVING NET& Yongman FRP CO. of China or Tripp Plastics, a division of Tripp Enterprises, Inc. of Sparks, Nevada.

[0027] Pressure may be used to actuate the fiber carrier in some instances. For example the fiber carrier 35 may be a hollow telescopic member that extends to run past the perforations 75 when actuated (e.g. by providing pressure through the connector 60 into the hollow portion or otherwise). In other words, pressure may be provided within the hollow portion to actuate the fiber carrier 35 causing it to extend outward (i.e., become elongated) such that the lower portion 5b is proximate the perforations 75.

[0028] Yet another example of a configuration for the fiber carrier 35 is a hollow spooled member that unrolls past the perforations when actuated (e.g. by providing pressure through the collar into the hollow portion or otherwise). In other words, pressure may be provided within the hollow portion to actuate the fiber carrier 35 causing it to uncurl or unspool (i.e., become elongated) such that the lower portion 5b is proximate the perforations 75.

[0029] The fiber carrier 35 may have a leading edge 80 configured to prevent engagement with the casing 10 and any uncased portion of the wellbore 25. For example, an elastomeric ball (not shown) may be provided at the leading edge 80, or the leading edge might have a rounded or other profile that resists frictionally engaging edges in the wellbore 25. Similarly, the fiber carrier 35 may have a friction-reducing configuration to prevent undesired engagement with the wellbore 25 prior to the lower portion 5b being placed. The fiber carrier 35 may be noncorrosive, oleophobic and/or elastic, etc.

[0030] Notably, while the perforations 75 are shown in a cemented section of the wellbore 25, it is possible to use the methods described to place the lower portion 5b in areas that are below the casing 10. Likewise, while a primary completion is shown, the method may be used in a retrofit operation. In such instance, prior to the steps indicated above, the existing production tubing (not shown) might be pulled from the wellbore 25 and the upper portion 5 a may be fed through a penetrator (not shown) in a tubing hanger (not shown) via a separate spool of optical fiber.

[0031] In this manner, the optical fiber 5 can be introduced after the casing 10 is already secured in place with cement 20. Thus, one or more optical fibers 5 may be deployed for downhole monitoring by means of recompletion of an existing well. It is believed that the methods described may be useful in both vertical and deviated wells by carrying the optical fiber 5 past perforations 75 without inhibiting the flow therethrough. This may also allow good thru-tubing access to the payzone.

[0032] Conventionally, robust cables have been used to provide protection of optical fibers used in harsh environments such as wellbores. However, if optical fibers can be placed at a point in time when fewer impacts from wellbore tools and other likely damaging conditions are expected, the redundancy and protective bulk may be reduced or even eliminated, allowing for more working space in the wellbore. In some instances, the optical fibers may still become damaged after one or more operations. However, the expected cost of running a replacement optical fiber is believed to be very low as compared to the cost of running the conventional optical fibers encased in cable at the conventional time (i.e., at completion). Thus, while the foregoing description might be applicable to conventional cable-encased optical fibers, additional advantage may be attained using unconventional optical fiber configurations. For example, the optical fiber may be constructed with Kevlar reinforcing, glass coating, glass encapsulation, Teflon, resin soaking, braiding, spinning, spooling, weaving, yarns, multiple reels, etc. The relatively slim profile of these unconventional optical fiber configurations, as compared to conventional cables, may allow for fiber placement at a much later point in the process, allowing placement to be tailored for the specific application. In some instances, if the fiber is slim enough, packers and other wellbore devices may be used with decreased risk of leakage as compared to a cable-encased fiber.

[0033] In the description above, the term "optical fiber" is intended to refer to a single thread or to a group of threads acting as a cohesive unit. Generally, optical fibers are constructed of glass. Also, glass fibers may be an integral part of a fiber thread. However, other materials may also be used as optical fibers, as will be appreciated by one having ordinary skill in the art.

Claims

C L A I M S

1. A method of providing optical fiber in a wellbore, comprising:

attaching an upper portion of the optical fiber along a production tubing;

lowering the production tubing into the wellbore;

attaching a lower portion of the optical fiber to a fiber carrier;

lowering the fiber carrier through the production tubing; and

attaching a proximal end of the fiber carrier to a distal end of the production tubing.

2. The method of claim 1 wherein attaching the upper portion of the optical fiber along the production tubing comprises attaching the upper portion of the optical fiber along an exterior of the production tubing.

3. A method of providing optical fiber in a wellbore, comprising:

providing a production tubing in the wellbore with an upper portion of the optical fiber along the production tubing;

attaching a lower portion of the optical fiber to a fiber carrier;

lowering the fiber carrier through the production tubing; and

4. The method of claim 3, wherein the optical fiber is provided along an exterior of the production tubing.

5. The method of claim 1 or claim 3, further comprising:

connecting or splicing the upper portion to the lower portion.

6. The method of claim 1 or claim 3, wherein the fiber carrier comprises an elongated rigid body, and wherein attaching the proximal end of the fiber carrier to the distal end of the production tubing results in the lower portion being proximate perforations in the wellbore.

7. The method of claim 1 or claim 3, wherein the fiber carrier comprises a hollow

telescopic member, the method further comprising:

actuating the fiber carrier;

wherein actuating the fiber carrier results in the lower portion being proximate

perforations in the wellbore.

8. The method of claim 1 or claim 3, wherein the fiber carrier comprises a hollow spooled member, the method further comprising:

actuating the fiber carrier; wherein actuating the fiber carrier results in the lower portion being proximate perforations in the wellbore.

9. The method of claim 3, further comprising removing a previously placed lower portion.

10. A device for providing optical fiber in a wellbore, comprising:

a fiber carrier configured to pass through production tubing; and

a lower portion of the optical fiber attached to the fiber carrier;

wherein the fiber carrier has a proximal end configured to attach to a distal end of the production tubing such that the lower portion is in optical communication with an upper portion of the optical fiber present along the production tubing.

11. The device of claim 10, wherein the fiber carrier comprises an elongated rigid body.

12. The device of claim 10, wherein the fiber carrier comprises a hollow telescopic

member.

13. The device of claim 10, wherein the fiber carrier comprises a hollow spooled member.