Bend limiter with monitoring device

A system is used to reduce the bending moments in Coil Tubing (“CT”). The system includes a segmented and closable cage that can close around the CT. The cage includes rollers, such as elastomeric rollers, that can allow for both vertical translations of the CT and rotations of the CT around the vertical axis. The cage rests on a seat, such as an elastomeric seat, provided inside a cylindrical housing. In order to monitor the bending moments in the CT, the pins that hold in the rollers are preferably load pins. This bend limiting system can be located below the CT injector, at the vessel deck level, or in the moonpool. The bend limiting system can be used in offshore or land operations.

FIELD AND BACKGROUND OF THE INVENTION

The disclosure relates generally to Coil Tubing (“CT”). The disclosure relates more particularly to a bend limiter, which preferably includes a device for monitoring the bending moments on the CT and a method of use thereof.

CT has been used for the performance of multiple types of hydraulic intervention, some of which involve the use of chemicals that promote rapid metal fatigue of the CT. For example, U.S. Pat. No. 9,695,665 describes a chemical injection system that includes CT. Regardless of the internal fluid contents, the bottom of the CT injector head is often not conducive to long-term deployment due to high-stress concentrations caused by bending moments and little ability to mitigate them.

There is a need in the art for a bend limiter for CT. Preferably, the bend limiter allows for the monitoring of the bending moments on the CT.

SUMMARY

The disclosure describes a bend limiter for CT.

The bend limiter may comprise a cage. The cage may include a first segment, a second segment, and an external flange. The cage may have an open configuration wherein the second segment is movable relative to the first segment. The cage may have a closed configuration wherein the second segment abuts against the first segment. For example, the second segment may be coupled to the first segment by a hinge so that the second segment is capable of rotating relative to the first segment about an axis of rotation. The second segment may include one of a plurality of hooks or a pin. The first segment may include the other of the plurality of hooks or the pin. In the closed configuration, each of the plurality of hooks may engage the pin. The external flange may include a first portion fixed to the first segment and a second portion fixed to the second segment. In the closed configuration, the first portion and the second portion may form a ring. Preferably, the ring may be located at a distal end of the cage along the axis of rotation.

The bend limiter may comprise a first plurality of rollers. For example, the first plurality of rollers may consist of three rollers. Each of the first plurality of rollers may be mounted to the first segment. Further, the bend limiter may comprise a second plurality of rollers. For example, the second plurality of rollers may consist of three rollers. Each of the second plurality of rollers may be mounted to the second segment. Each of the first plurality of rollers and/or each of the second plurality of rollers may include an elastomer wheel. In the open configuration, CT may be placed in contact with each of the first plurality of rollers and not in contact with any of the second plurality of rollers. In the closed configuration, CT may be placed in contact with the first plurality of rollers and the second plurality of rollers simultaneously. Also, in the closed configuration, the first plurality of rollers and the second plurality of rollers may allow for the CT to move relative to the bend limiter in a first direction. The first direction may be parallel to the axis of rotation of the second segment relative to the first segment.

Preferably, at least some of the first plurality of rollers may be mounted to the first segment via a corresponding one of a first plurality of load pins. For example, each of the first plurality of rollers may be mounted to the first segment via a corresponding one of the first plurality of load pins. Preferably, at least some of the second plurality of rollers are mounted to the second segment via a corresponding one of a second plurality of load pins. For example, each of the second plurality of rollers may be mounted to the second segment via a corresponding one of the second plurality of load pins. Each of the first plurality of load pins may allow measurement of a force applied to it. Similarly, each of the second plurality of load pins allows measurement of a force applied to it. Optionally, each of the first plurality of load pins may be located in one of a plurality of planes that is perpendicular to the first direction, and each of the second plurality of load pins is located in one of the plurality of planes.

The bend limiter may comprise a basket. The basket may include a housing having an internal shoulder. The housing may include a split cylinder and a tic-back capable of being connected to one of an injector head, a vessel deck, or a moonpool wall. The basket may further include an elastomer seat. The elastomer seat may be located above the internal shoulder. In the closed configuration, the cage may be capable of being introduced inside the housing. Also, in the closed configuration, the external flange may be capable of resting on the elastomer seat.

The disclosure describes a method of reducing bending moments in CT.

The method may comprise the step of providing a bend limiter, as described herein above.

The method may comprise the step of connecting the housing of the bend limiter to one of an injector head, a vessel deck, or a moonpool wall.

The method may comprise the steps of opening the cage of the bend limiter and then placing CT in contact with each of the first plurality of rollers and not in contact with any of the second plurality of rollers.

Then, the method may comprise the steps of closing the cage, placing the CT in contact with the first plurality of rollers and the second plurality of rollers simultaneously, and introducing the cage inside the housing.

Then, the method may comprise the step of moving the CT relative to the bend limiter in the first direction. During the movement of the CT, the method preferably, but not necessarily, comprises the step of monitoring the bending moments on the CT with load pins used to mount the first plurality of rollers on the first segment and the second plurality of rollers on the second segment. The operation of the CT may be adjusted based on the monitored bending moments.

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.

The disclosure describes a bend limiting system or guide that can provide the ability to increase the effective fatigue life of CT by reducing the bending moments in CT.

Normal operations for CT include being able to adjust the length of CT deployed at various times in the operation, which requires any bend limiting system to be able to provide the ability to have CT move relative to the bend limiting system.

In addition to providing the bend limiting function, the bend limiting system can optionally also provide the capability to directly monitor the bending moments on CT. Current methods are approximate and do not monitor directly.

The bend limiting system includes a device, such as a segmented and closable cage or housing that can close around the CT, which will also provide movement of the CT, potentially both for vertical translations of the CT and rotations of the CT around the vertical axis. This can be accomplished by a number of means, some of which involve fixed elastomers and rollers, which are in the cage.

The preferred embodiment is to have elastomeric rollers, which will then allow the CT to be paid in or out. In this embodiment, the pins that hold in the elastomeric rollers can then be load pins, which will allow the direct measurement of the forces through the pins and therefore provide a direct measurement of the bending moment imparted by the CT on the bend limiting system. This bending moment can then be used to approximate the stresses in the CT.

Stresses in the CT are sometimes highly concentrated at the exit to the injector head. If these stresses can be reduced, the remaining fatigue problem can be greatly reduced.

This bend limiting system can be at several potential locations on the vessel. One potential location is directly below the CT injector head, which will act similarly to a riser stress joint with one end fixed. Another potential location is at the vessel deck level just below the CT injector head, in which case, some rotational stiffness will provide additional reduction of the stresses at the injector head location. A third potential location is in the moonpool itself, somewhere below the upper deck and above the keel of the vessel. Lateral support of the bend limiting system can be more complex to provide in this location, which can be solved either with the implementation of a track system on the moonpool wall or by restraining the movement of the bend limiting system through the use of taut lines that are connected back to the walls of the moonpool and tightened by lines to the surface of the vessel.

The bend limiting system can also be used in land operations.

In reference toFIGS.1and2, offshore operations involving bend limiters30and31are illustrated. Two CT units are located on the deck of a vessel (not shown). The first CT unit includes a CT injector head10, through which CT20is injected. The second CT unit includes a CT injector head11, through which CT21is injected. In the example shown, bend limiter30is connected to a vessel deck (shown inFIG.2), and bend limiter31is connected to the bottom of CT injector head11.

In other examples, bend limiter30can instead be connected to a moonpool wall (not shown). Also, several bend limiters can be connected along CT20and/or CT21.

In reference toFIG.2A, the bend limiter30comprises a basket32and a cage34.

The basket32comprises a housing (e.g., including a tie-back35connected to the vessel deck) having an internal shoulder33. The basket32also comprises an elastomer seat36located on top of the internal shoulder33.

The cage34comprises an external flange31. The cage34also comprises rollers (e.g., first rollers37aand second rollers37bin the same plane48) that guide the CT20so as to limit its bending.

In reference to the top ofFIG.3and the left ofFIG.4, the closed configuration of the cage34is illustrated. In reference to the bottom ofFIG.3and the right ofFIG.4, the open configuration of the cage34is illustrated. The cage34moves from the closed configuration to the open configuration by rotating segment42relative to segment41around the axis of hinge40. In the closed configuration, hooks44engage a pin46.

In reference toFIG.5, the cage34is closed on CT20(right ofFIG.5). Then, the CT is placed inside the housing of the basket32via a gap into split cylinder39(middle ofFIG.5). Then, the cage34rests on the elastomer seat36(left ofFIG.5).

The claimed invention is susceptible to various modifications and alternative forms, and specific embodiments thereof are shown by way of example in the drawings and description. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the claims to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the claims.