APPARATUS AND METHOD FOR REDUCING THE RESIDUAL BENDING AND FATIGUE IN COILED TUBING

Abstract

The subject disclosure provides a reel and a gooseneck which significantly reduce residual bending of the coiled tubing. The subject disclosure discloses a gooseneck that provides reverse bending forces to reduce the residual bending as a result of the reel. Further, the subject disclosure discloses a gooseneck having an adjustable radius during the coiled tubing operations which optimizes the residual bending process. The subject disclosure also discloses a heating and cooling module. The heating and cooling modules are attached to the gooseneck and are used to reduce fatigue of the coiled tubing and elongate the life cycle of the coiled tubing.

Description

FIELD OF THE DISCLOSURE

The subject disclosure generally relates to the field of coiled tubing and coiled tubing applications in hydrocarbon wells. More particularly, the subject disclosure relates to reducing residual bending and fatigue of coiled tubing.

BACKGROUND OF THE DISCLOSURE

Coiled tubing refers to metal piping, used for interventions in oil and gas wells and sometimes as production tubing in depleted gas wells, which comes spooled on a large reel. Coiled tubing operations typically involve at least three primary components. The coiled tubing itself is disposed on a reel and must, therefore, be dispensed onto and off of the reel during an operation. The tubing extends from the reel to an injector. The injector moves the tubing into and out of the wellbore. Between the injector and the reel is a tubing guide or gooseneck. The gooseneck is typically attached or affixed to the injector and guides and supports the coiled tubing from the reel into the injector. Typically, the tubing guide is attached to the injector at the point where the tubing enters. As the tubing wraps and unwraps on the reel, it moves from one side of the reel to the other (side to side).

Residual bend exists in every coiled tubing string. During storage and transportation, a coiled-tubing string is plastically deformed (bent) as it is spooled on a reel. During operations, the tubing is unspooled (bent) from the reel and bent on the gooseneck before entering into the injector and the wellbore. Residual bending is one of the technical challenges for coiled tubing operations and originates from the spool of the coiled tubing on the reel. Although the reel is manufactured in a diameter as large as possible to decrease the residual bending incurred on the coiled tubing, the maximum diameter of many reels is limited to several meters due to storage and transportation restrictions.

Coiled tubing is susceptible to a condition known as helical buckling of the tubing which leads to lockup. Residual bending of the coiled tubing increase the susceptibility of the coiled tubing to helical buckling and lockup. As the coiled tubing goes through the injector head, it passes through a straightener; but the tubing retains some residual bending strain corresponding to the radius of the spool. That strain gives the tubing a helical form when deployed in a wellbore and can cause it to wind axially along the wall of the wellbore like a long, stretched spring. Ultimately, when a long enough length of coiled tubing is deployed in the well bore, frictional forces from the wellbore wall rubbing on the coiled tubing cause the tubing to bind and lock up, thereby stopping its progression. Lock up limits any further progression as the coiled tubing cannot be pushed further by a force applied at the surface. (Lubinski, A., Althouse, W. S., and Logan, J. L., “Helical Buckling of Tubing Sealed in Packers,” SPE 178, 1962). Such lock up limits the use of coiled tubing as a conveyance member for logging tools in highly deviated, horizontal, or up-hill sections of wellbores. Therefore, reducing the residual bending of the coiled tubing before the coiled tubing is placed into the wellbore can increase the extended reach of the coiled tubing (Zheng, A. and Adnan, S., “The Penetration of Coiled Tubing with Residual Bend in Extended-Reach Wells,” SPE 95239, 2007). Residual bending also decreases the fatigue life for coiled tubing, therefore, reducing residual bending will thus increase the fatigue life of coiled tubing (Bhalla, K., “Coiled Tubing Extended Reach Technology,” SPE 30404, 1995). Fatigue failure of coiled tubing is a serious concern because of plastic deformation caused by repeated bending on the reel and gooseneck.

Coiled tubing passing downward (generally running-in hole) undergoes at least three straining events: 1) as the coiled tubing is straightened upon leaving the reel and on approach to the gooseneck; 2) as the coiled tubing is curved over the gooseneck; and 3) as the coiled tubing is straightened on its way from the gooseneck to the injector head. Similarly, coiled tubing passing upward (generally pulling-out-of-hole) undergoes at least three straining events: 1) as the coiled tubing is extracted from the wellbore and curved over the gooseneck; 2) as the coiled tubing is straightened upon leaving the gooseneck and on approach to the reel; and 3) as the coiled tubing is being curved onto the reel. These strains in coiled tubing may cause residual bend in the tubing which may prevent it from straightening properly in the borehole or rolling properly on the reel.

Residual bending is reduced by the straightener. The straightener applies compressive forces around the coiled tubing before the coiled tubing is placed into the wellbore, straightening the coiled tubing and reducing some of the residual bending in the coiled tubing. However, the tubing retains some residual bending. Furthermore, the straightener is unable to reduce fatigue of the coiled tubing or elongate the life cycle of the coiled tubing.

Mueller et al, (U.S. Pat. No. 5,291,956) proposes a method for reducing the residual bending using a pulley. However, the pulley has a diameter near to the diameter of the reel and occupies additional space for the coiled tubing unit.

The presently disclosed subject matter addresses the problems of the prior art by addressing residual bending and fatigue of the coiled tubing. The presently disclosed subject matter reduces residual bending and fatigue of the coiled tubing, which assists in extending the maximum reach of the coiled tubing in the wellbore and the life cycle of the coiled tubing respectively.

SUMMARY OF THE DISCLOSURE

In view of the above there is a need for an improved mechanism which reduces residual bending in coiled tubing. Further there is a need for an improved mechanism to reduce fatigue of the coiled tubing and elongate the life cycle. The subject technology accomplishes these and other objectives. The subject disclosure provides a method of reducing residual bending and fatigue in the coiled tubing by utilizing a reel and gooseneck. The subject disclosure discloses a gooseneck that provides an opposite bending moment to reduce the residual bending in the coiled tubing as a result of the reel. Further, the subject disclosure discloses a gooseneck having an adjustable radius during the coiled tubing operations which optimizes the residual bending reduction process. The subject disclosure also discloses a heating and cooling module. The heating and cooling modules are attached to the gooseneck and are utilized to increase the efficiency of the residual bending process and reduce fatigue of the coiled tubing.

In accordance with an embodiment of the subject disclosure, an apparatus for reducing residual bending in coiled tubing is disclosed. A gooseneck is positioned to receive the coiled tubing from the coiled tubing reel and once positioned reverse bends the coiled tubing to an extent sufficient to remove residual bend resulting from the coiled tubing being coiled on the reel.

In accordance with a further embodiment of the subject disclosure, a method for reducing residual bend from a reel is disclosed. A gooseneck is positioned to reverse bend the coiled tubing sufficiently to remove residual bend resulting from the coiled tubing being coiled on the reel.

Further features and advantages of the subject disclosure will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the coiled tubing operating environment for the subject disclosure;

FIG. 2 represents a coiled tubing unit having a hydraulically operated tubing reel and shows the bending events that coiled tubing undergoes while moving from the coiled tubing reel to the main injector;

FIG. 3 illustrates one embodiment of the subject disclosure;

FIG. 4 illustrates a second embodiment of the subject disclosure;

FIG. 5 illustrates the embodiment of FIG. 1 with a heating and cooling module;

FIG. 6 illustrates the embodiment of FIG. 2 with a heating and cooling apparatus;

FIG. 7 illustrates a gooseneck having an adjustable radius of curvature; and

FIG. 8 is the bending moment M—curvature 1/ρ curve of coiled tubing under elastically-perfectly plastic deformation.

DETAILED DESCRIPTION

Embodiments of the present technology comprise a reel and a gooseneck which significantly reduce residual bending of the coiled tubing.

In FIG. 1 the operating environment of the subject disclosure is shown. Coiled tubing operation comprises a truck 103 and/or trailer 109 that supports power supply 105 and tubing reel 107. An injector unit head 111 feeds and directs coiled tubing 113 from the tubing reel into the subterranean formation. The configuration of FIG. 1 shows a horizontal wellbore configuration which supports a coiled tubing trajectory 115 into a horizontal wellbore 117. The subject disclosure is not limited to a horizontal wellbore configuration but may also be used in vertical and deviated wells, both on land and offshore. Downhole tool 119 is connected to the coiled tubing, as for example, to conduct flow or measurements, or perhaps to provide diverting fluids.

FIG. 2 depicts a coiled tubing assembly 211. The coiled tubing assembly 211 is composed of coiled tubing 203, reel 201 and a gooseneck 205. When the coiled tubing assembly is run into the wellbore the coiled tubing 203 spooled onto the reel 201 is unwound first and then delivered through a levelwind assembly 212 and a coiled tubing brake 214 in a controllable way. The coiled tubing spooled on the reel 201 is plastically deformed, resulting in residual bending in the coiled tubing. The forces and strains placed upon coiled tubing when it is used in a coiled tubing unit 211 are apparent from viewing FIG. 2. Coiled tubing undergoes numerous bending events each time it is run into and out of a wellbore. Coiled tubing 203 is straightened when it emerges from the reel by way of the levelwind assembly 212. A levelwind assembly for a coiled tubing reel guides coiled tubing onto a reel when the coiled tubing is removed from an oil or gas well and guides coiled tubing from the reel when the coiled tubing is injected into an oil or gas well. Levelwind assemblies are known to those skilled in the art. One such levelwind assembly is describe in U.S. Pat. No. 6,264,128, entitled “Levelwind Assembly for Coiled Tubing Reel”, incorporated herein in its entirety by reference. Coiled tubing brake 214 on the levelwind assembly 212 is shown. The coiled tubing 203 is guided by the gooseneck 205, and is straightened as it goes into the injector head 207 for entry into the wellbore. Of course, each bending event is repeated in reverse when the tubing is later extracted from the wellbore. These bending events weaken the tubing each time it is used, and tubing use must be monitored. Tubing is discarded when it has been used beyond an acceptable safety limit as indicated by reaching predicted fatigue limits. The coiled tubing, typically made of steel, is plastically deformed every time it is spooled off the reel, bent over the gooseneck, straightened through the chains, and in the reverse process. It is known that the fatigue resistance of steel is severely degraded when it is plastically deformed. Residual bending in the coiled tubing 203 is not reduced when the coiled tubing 203 is guided by the gooseneck 205. When the coiled tubing 203 slides through the injector head 207, the injector head 207 exerts a compressive force around the coiled tubing which straightens the coiled tubing. Finally, after the coiled tubing is straightened by the injector head 207, the residual bending in the coiled tubing 209 is reduced before the coiled tubing 209 is run into the wellbore.

FIG. 3 show a reel 301 of coiled tubing 305 stored on a drum in a clockwise direction 309. As the coiled tubing 305 slides through the gooseneck 303 the coiled tubing 305 unwinds in a counter-clockwise direction 311, and continues unwinding in a counter-clockwise direction 311 as it is placed into a wellbore (not shown). The reel 301 spooled with coiled tubing 305 rotates in a clockwise direction 309 while the coiled tubing 305 is guided by the gooseneck 303 in a counter-clockwise direction 311 when the coiled tubing is run into a wellbore. Once the coiled tubing 305 leaves the reel 301, the residual bending existing in the coiled tubing 305 is compensated by an opposite bending moment exerted by the gooseneck 303 and the residual bending in the coiled tubing 307 is reduced. The opposite bending moment means the sign of the bending moment M is different, i.e. clockwise or anti-clockwise. Once the coiled tubing 305 has travelled through the gooseneck 303, residual bending in the coiled tubing 305 will be significantly reduced. Residual bending of the coiled tubing is significantly reduced as a result of the reverse unwinding of the coiled tubing, in this instance in a counter-clockwise direction. The radius profile of the gooseneck 303 is adjustable during the coiled tubing operation for optimal reduction of residual bending.

FIG. 4 shows a reel 401 of coiled tubing 403 stored on a drum in a counter-clockwise direction 411. The reel 401 spooled with coiled tubing 403 rotates in a counter-clockwise direction 411 and the coiled tubing is guided by a first section of the gooseneck 409 in the same counter-clockwise direction when running the coiled tubing into well. A second section of the gooseneck 407 enables rotation of the coiled tubing in a clockwise direction 415. The coiled tubing 403 enters a first section 409 of the gooseneck in a counter-clockwise direction 413. The gooseneck further comprises a second section 407. The coiled tubing 403 enters in a clockwise direction 415 into the second section 407 of the gooseneck. The residual bending existing in the coiled tubing 403 is compensated by an opposite bending moment exerted by the second section 407 of the gooseneck on the coiled tubing 403 and the residual bending in the coiled tubing 405 is reduced. Once the coiled tubing moves through the second section 407 of the gooseneck the residual bending in the coiled tubing 403 will be significantly reduced. The radius profile of the second section 407 of the gooseneck is adjustable for optimal reduction of residual bending.

FIG. 5 illustrates the schematic of FIG. 3 further comprising a heating and cooling module. FIG. 5 depicts a reel 505 of coiled tubing 507 stored on a drum in a clockwise direction 513. A heating module 503 is attached to the gooseneck 501 and a cooling module 509 surrounds the coiled tubing 507. The heating module 503 heats the coiled tubing 507 and enables the residual bending reduction process in a high temperature. In certain non-limiting examples the temperature may reach 600° C. A high temperature increases the efficiency of reducing residual bending and reducing fatigue of the coiled tubing 507. The cooling module 509 controls the temperature of the coiled tubing 507 ensuring the high temperature is in an area close to the gooseneck 501. Thus, the cooling module 509 confines the high temperature of the coiled tubing 507 to a region close to the gooseneck 501.

FIG. 6 illustrates the schematic of FIG. 4 further comprising heating and cooling modules. FIG. 6 depicts a reel 609 of coiled tubing 613 stored on a drum in a counter-clockwise direction 615. A heating module 603 is attached to a second section 603 of gooseneck and a cooling module 605 surrounds the coiled tubing 613 on either end of the gooseneck 601. Similar to the embodiment of FIG. 5 the heating module 603 heats the coiled tubing 605 and enables the residual bending reduction process in a high temperature. A high temperature increases the efficiency of reducing residual bending and reducing fatigue of the coiled tubing 605. The cooling module 605 controls the temperature of the coiled tubing 605 ensuring the high temperature is in an area close to the second section 611 of the gooseneck. Thus, the cooling module 605 confines the high temperature of the coiled tubing 613 to a region close to the area of the second section 611 of the gooseneck.

The configuration of the gooseneck 303 and the second section of the gooseneck 407 are adjustable during an individual coiled tubing operation or multiple coiled tubing operations. For the individual coiled tubing operation, the configuration of the gooseneck 303 or 407 changes as different locations of the coiled tubing are guided by the gooseneck 303 or 407. The magnitude of the residual bending of the coiled tubing varies depending on the location of the coiled tubing on the reel. The coiled tubing spooled on the outside of the reel experiences less plastic deformation than the coiled tubing spooled on the inner side of the reel. The radius of curvature of the gooseneck 303 or 407 may be adjusted from a large curvature to a smaller curvature as more coiled tubing is unwound from the reel when the coiled tubing is run into the wellbore.

For the multiple coiled tubing operations, the configuration of the gooseneck 303 or 407 changes as the diameter of the reel changes. The magnitude of the residual bending of the coiled tubing varies depending on the diameter of the reel. The coiled tubing spooled on large reels experiences less plastic deformation than the coiled spooled on smaller reels. The radius of curvature of the gooseneck 303 or 407 is adjusted to a larger radius if the coiled tubing is spooled on a larger reel. The radius of curvature of the gooseneck 303 or 407 is adjusted to a smaller radius if the coiled tubing is spooled on a smaller reel.

FIG. 7 schematically illustrates a gooseneck 701 with an adjustable radius of curvature. The gooseneck has the largest radius of curvature when segment 714, segment 715, segment 716, and the plurality of other segments (not listed) are expanded. Joint 713 is fixed on the segment 714. Joint 705 and joint 709 are fixed on the gooseneck base 703. When the radius of curvature of the gooseneck decreases, segment 715 collapses into segment 714. At the same time, upper supporting arms 711 rotate around joint 713 and lower supporting arms 707 rotate around joint 705 and joint 709 to achieve a new balanced position. When the radius of curvature of the gooseneck further decreases, segment 716 also collapses into segment 714, upper arms 711 and lower arms 707 change their positions accordingly, to a different balanced position. One skilled in the art will appreciate that adjusting the radius of curvature can be accomplished using many other techniques known to those skilled in the art and not described in the subject disclosure.

The significance of the residual bending can be described quantitatively by using bending strain. The maximum magnitude of the bending strain ε_max in a given pipe cross-section usually occurs on the outside of the pipe. The radius of the reel is ρ₀ and the coiled tubing outside diameter is D_o. When the number of the loops of the coiled tubing spooled on the reel is n, the curvature ρ of the coiled tubing of the i^th loop is:

ρ=β₀+i·D_o(i=1, 2 . . . n)  (1)

The relationship between the maximum bending strain ε_max, curvature 1/ρ, and the pipe outside diameter D_o is:

|ε_max|=|(D_o/2)(1/ρ)|  (2)

As can be seen from Eq. (2), the residual bending is significant when the pipe outside diameter D_o is large and the radius ρ is small. As can be seen from Eq. (1), the radius ρ is small when the radius of the reel ρ_o is small and the number of the loops n is small.

FIG. 8 depicts the bending moment M—curvature (ρ) of a pipe undergoing a series of deformations. In a non-limiting example this pipe may be a portion of coiled tubing. The material is assumed to be elastically-perfectly plastic. In a first deformation from A to B the pipe undergoes linear elastic bending. Further bending from B to C results in deformation which is elastic-plastic, this means that some parts of a cross-section are deforming plastically and some parts of a cross-section are deforming elastically. The deformation from A to C may be representative of placing a straight coiled tubing string onto a reel. The pipe unloads elastically from C-D, the curvature at D would be the residual bend if no further deformation occurred e.g. if a coiled tubing was unwound from the reel without a straightening process. If the pipe is then straightened, the deformation will unload elastically from D to E and then elastically-plastically from E to F. At F, the pipe will be straight. If the pipe then unloads elastically, it will proceed from F to G and have a residual bend shown by the curvature at G. If the pipe is then reverse-bent, the deformation will proceed from F to G′, with further elastic-plastic deformation. Upon unloading elastically from G′, the pipe returns to the initial state A with no residual bend, providing G′ has been selected appropriately. In one non-limiting example G′ would be estimated by reverse bending to the same curvature as seen at G, i.e. reverse bending by the same amount as the residual curvature if in the absence of the reverse bend operation.

Reverse bending may also occur elsewhere in the coiled tubing e.g. injector. Although the embodiments of the subject disclosure have been described with respect to coiled tubing, the mechanisms disclosed may reduce residual bending of tubing in general.

While the subject disclosure is described through the above exemplary embodiments, it will be understood by those of ordinary skill in the art that modification to and variation of the illustrated embodiments may be made without departing from the inventive concepts herein disclosed. Moreover, while the preferred embodiments are described in connection with various illustrative structures, one skilled in the art will recognize that the system may be embodied using a variety of specific structures. Accordingly, the subject disclosure should not be viewed as limited except by the scope and spirit of the appended claims.

Claims

1) An apparatus for reducing residual bending in coiled tubing from a reel comprising:

a gooseneck positioned to receive the coiled tubing from the coiled tubing reel and to cause the coiled tubing to reverse bend to an extent sufficient to remove residual bend resulting from the coiled tubing being coiled on the reel.

2) The apparatus of claim 1 wherein the gooseneck guides the coiled tubing in a second rotation direction opposite to a first rotation direction of the coiled tubing on the reel.

3) The apparatus of claim 1 wherein a radius of curvature of the gooseneck is adjustable.

4) The apparatus of claim 3 wherein a magnitude of the reverse bend is controlled by adjusting the radius of curvature of the gooseneck.

5) The apparatus of claim 1 wherein the gooseneck further comprises:

a first section of gooseneck guiding the coiled tubing in a first rotation direction and a second section of gooseneck guiding the coiled tubing in a second rotation direction opposite to the first rotation direction.

6) The apparatus of claim 5 wherein the first rotation direction is the same as a rotation direction of the coiled tubing on a reel.

7) The apparatus of claim 5 wherein a radius of curvature of the second section of gooseneck is adjustable.

8) The apparatus of claim 1 wherein a portion of the gooseneck comprises a plurality of segments.

9) The apparatus of claim 8 wherein the plurality of segments are used to adjust a radius of curvature.

10) The apparatus of claim 8 wherein the plurality of segments are collapsible thus decreasing a radius of curvature.

11) The apparatus of claim 8 wherein the plurality of segments are expandable thus increasing a radius of curvature.

12) The apparatus of claim 4 wherein the radius of curvature changes as a diameter of the reel changes.

13) The apparatus of claim 4 wherein the radius of curvature changes as the coiled tubing is wound or unwound from the reel.

14) The apparatus of claim 1 further comprising a heating module and a cooling module.

15) The apparatus of claim 14 wherein the heating module is attached to the gooseneck.

16) The apparatus of claim 14 wherein the cooling module is wrapped around the coiled tubing proximal to the gooseneck.

17) The apparatus of claim 16 wherein the cooling module confines a high temperature of the coiled tubing to an area proximal to the gooseneck.

18) A method for reducing residual bending in coiled tubing from a reel comprising:

positioning a gooseneck and receiving the coiled tubing from the coiled tubing reel with the positioned gooseneck;

with the positioned gooseneck causing the coiled tubing to reverse bend to an extent sufficient to remove residual bend resulting from the coiled tubing being coiled on the reel.

19) The method of claim 18 wherein with the gooseneck guiding the coiled tubing in a second rotation direction opposite to a first rotation direction of the coiled tubing on a reel.

20) The method of claim 18 wherein the gooseneck further comprises:

a first section of gooseneck guiding the coiled tubing in a first rotation direction and a second section of gooseneck guiding the coiled tubing in a second rotation direction opposite to the first rotation direction.

21) The method of claim 20 wherein the first rotation direction is the same as a rotation direction of the coiled tubing on a reel.

22) The method of claim 18 further comprising:

adjusting a radius of curvature of the gooseneck.