US20070140797A1

US20070140797A1 - Systems and methods for installation of clamshell devices around an element

Info

Publication number: US20070140797A1
Application number: US11/612,203
Authority: US
Inventors: Stephen Armstrong
Original assignee: Individual
Current assignee: Shell USA Inc
Priority date: 2005-12-19
Filing date: 2006-12-18
Publication date: 2007-06-21

Abstract

Systems and methods for remotely installing a clamshell device around an element, the clamp system comprising a body; and at least one set of clamps supported by the body, the set suitable for holding and releasing the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices, wherein at least one clamp comprises a cam surface adapted to engage the element and close the clamp about the element.

Description

RELATED APPLICATION DATA

This application claims priority to U.S. Provisional Application 60/751,503, filed Dec. 19, 2005. U.S. Provisional Application 60/751,503 is herein incorporated by reference in its entirety.
This application is related to U.S. patent application Ser. No. 11/083,833, filed Mar. 18, 2005, having Attorney Docket Number TH1853-03; U.S. patent application Ser. No. 10/383,154, filed Mar. 6, 2003; U.S. patent application Ser. No. 10/032,710, filed Oct. 19, 2001. U.S. patent application Ser. No. 11/083,833, U.S. patent application Ser. No. 10/383,154, and U.S. patent application Ser. No. 10/032,710 are herein incorporated by reference in their entirety.

FIELD OF THE INVENTION

In one aspect, the invention relates to systems and methods for installing clamshell devices around an element.

DESCRIPTION OF THE RELATED ART

Whenever a bluff body, such as a cylinder, experiences a current in a flowing fluid environment, it is possible for the body to experience vortex-induced vibrations (VIV). These vibrations are caused by oscillating dynamic forces on the surface, which can cause substantial vibrations of the structure, especially if the forcing frequency is at or near a structural natural frequency. The vibrations may be largest in the transverse (to flow) direction; however, in-line vibrations can also cause stresses, which are sometimes larger than those in the transverse direction.
Drilling for and/or producing hydrocarbons or the like from subterranean deposits which exist under a body of water exposes underwater drilling and production equipment to water currents and the possibility of VIV. Equipment exposed to VIV includes structures ranging from the smaller tubes of a riser system, anchoring tendons, or lateral pipelines to the larger underwater cylinders of the hull of a mini spar or spar floating production system (hereinafter “spar”).
There are generally two kinds of current-induced stresses in flowing fluid environments. The first kind of stress is caused by vortex-induced alternating forces that vibrate the structure (“vortex-induced vibrations”) in a direction perpendicular to the direction of the current. When fluid flows past the structure, vortices are alternately shed from each side of the structure. This produces a fluctuating force on the structure transverse to the current. If the frequency of this harmonic load is near the resonant frequency of the structure, large vibrations transverse to the current can occur. These vibrations can, depending on the stiffness and the strength of the structure and any welds, lead to unacceptably short fatigue lives. In fact, stresses caused by high current conditions in marine environments have been known to cause structures such as risers to break apart and fall to the ocean floor.
The second type of stress is caused by drag forces, which push the structure in the direction of the current due to the structure's resistance to fluid flow. The drag forces may be amplified by vortex-induced vibrations of the structure. For instance, a riser pipe that is vibrating due to vortex shedding will generally disrupt the flow of water around it more than a stationary riser. This may result in more energy transfer from the current to the riser, and hence more drag.
Many types of devices have been developed to reduce vibrations of sub sea structures. Some of these devices used to reduce vibrations caused by vortex shedding from sub sea structures operate by stabilization of the wake. These methods include use of streamlined fairings, wake splitters and flags.
Streamlined or teardrop shaped, fairings that swivel around a structure have been developed that almost eliminate the shedding of vortices. The major drawback to teardrop shaped fairings is the cost of the fairing and the time required to install such fairings.
Other devices used to reduce vibrations caused by vortex shedding from sub-sea structures operate by modifying the boundary layer of the flow around the structure to prevent the correlation of vortex shedding along the length of the structure. Examples of such devices include sleeve-like devices such as helical strakes, shrouds, fairings and substantially cylindrical sleeves.
Some VIV and/or drag reduction devices can be installed on risers and similar structures before those structures are deployed underwater. Alternatively, VIV and/or drag reduction devices can be installed by divers on structures after those structures are deployed underwater.
Use of human divers to install VIV and/or drag reduction equipment at shallower depths can be cost effective. However, strong currents can also occur at great depths causing VIV and/or drag of risers and other underwater structures at those greater depths. However, using divers to install VIV and/or drag reduction equipment at greater depths subjects divers to greater risks and the divers cannot work as long as they can at shallower depths. The fees charged, therefore, by diving contractors are much greater for work at greater depths than for shallower depths. Also, the time required by divers to complete work at greater depths is greater than at shallower depths, both because of the shorter work periods for divers working at great depths and the greater travel time for divers working at greater depths. This greater travel time is caused not only by greater distances between an underwater work site and the water surface, but also by the requirement that divers returning from greater depths ascend slowly to the surface. Slow ascent allows gases, such as nitrogen, dissolved in the diver's blood caused by breathing air at greater depths, to slowly return to a gaseous state without forming bubbles in the diver's blood circulation system. Bubbles formed in the blood of a diver who ascends too rapidly cause the diver to experience the debilitating symptoms of the bends.
Elongated structures in wind in the atmosphere can also encounter VIV and/or drag, comparable to that encountered in aquatic environments. Likewise, elongated structures with excessive VIV and/or drag forces that extend far above the ground can be difficult, expensive and dangerous to reach by human workers to install VIV and/or drag reduction devices.
U.S. Pat. No. 6,928,709 discloses apparatus and methods for remotely installing vortex-induced vibration (VIV) reduction and drag reduction devices on elongated structures in flowing fluid environments. The apparatus is a tool for transporting and installing the devices. The devices installed can include clamshell-shaped strakes, shrouds, fairings, sleeves and flotation modules. U.S. Pat. No. 6,928,709 is herein incorporated by reference in its entirety.
There are needs in the art for apparatus and methods for installing VIV and/or drag reduction devices on structures in flowing fluid environments; for apparatus and methods for installing VIV and/or drag reduction devices on structures in flowing fluid environments, which do not suffer from the disadvantages of the prior art apparatus and methods; for apparatus and methods for installing VIV and/or drag reduction equipment on underwater structures without using human divers; for apparatus and methods for installing VIV and/or drag reduction devices on underwater structures using equipment that can be remotely operated from the surface of the water; for apparatus and methods for installing VIV and/or drag reduction devices on above-ground devices using equipment that can be operated from the surface of the ground; for apparatus and methods for installing VIV and/or drag reduction devices on underwater structures using an ROV; and/or for apparatus and methods for installing various lengths of VIV and/or drag reduction devices.
These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.

SUMMARY OF THE INVENTION

One aspect of the invention provides a clamp system for remotely installing a clamshell device around an element, the clamp system comprising a body; and at least one set of clamps supported by the body, the set suitable for holding and releasing the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices, wherein at least one clamp comprises a cam surface adapted to engage the element and close the clamp about the element.
Another aspect of the invention provides a method of remotely installing a clamshell device having a longitudinal axis around an element, using a clamp system comprising at least one clamp with a cam surface, the method comprising positioning the clamp system adjacent to the element wherein the clamp system carries the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices; moving the clamp system to position the clamshell device around the element; moving the clamp system to engage the cam surface with the element to close the clamshell device around the element; and securing the device in position around the element.
These and other aspects of the invention will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.
Advantages of the invention may include one or more of the following: simplified systems and methods for closing clamshell devices about an element;

a system with a self-opening feature;
a system adapted to be used with an ROV;
a system adapted to install multiple clamshell devices about an element;
a system adapted to avoid the effects of heave.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of an apparatus for installing a clamshell device about an element.
FIG. 2 is the apparatus of FIG. 1 being engaged with the element.
FIG. 3 is the apparatus of FIG. 1 being engaged with the element.
FIG. 4 is a side view of a system for installing a clamshell device about an element.
FIG. 5 is a side view of a system for installing a clamshell device about an element.
FIG. 6 is a top view of a system installing a clamshell device about an element.
FIG. 7 is a top view of a system installing a clamshell device about an element.
FIG. 8 is a top view of a system after having installed a clamshell device about an element.
FIG. 9 is a system for installing clamshell devices about an element.
FIG. 10 is a system for installing clamshell devices about an element.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment, there is disclosed a clamp system for remotely installing a clamshell device around an element, the clamp system comprising a body; and at least one set of clamps supported by the body, the set suitable for holding and releasing the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices, wherein at least one clamp comprises a cam surface adapted to engage the element and close the clamp about the element. In some embodiments, the at least one set of clamps comprises a first clamp comprising a first cam surface, and a second clamp comprising a second cam surface. In some embodiments, the body has a top and a bottom, wherein the at least one set of clamps is comprised of a first set of clamps and a second set of clamps, wherein the first set of clamps is supported by the top of the body and the second set of clamps is supported by the bottom of the body. In some embodiments, there are at least two sets of clamps. In some embodiments, the at least one set of clamps holds the clamshell device. In some embodiments, the body has a taller first height and is collapsible to a shorter second height for holding shorter devices or for storage of the clamp system. In some embodiments, at least one clamp comprises at least one nipple, pin, screw, bolt, nail, adhesive, or other type of connector for anchoring the clamshell device to the set of clamps. In some embodiments, the clamp system also includes a release adapted to release the at least one nipple, pin, screw, bolt, nail, adhesive, or other type of connector so the clamshell device is not anchored to the set of clamps. In some embodiments, a plurality of clamps comprises a cam surface. In some embodiments, each clamp comprises a cam surface. In some embodiments, the clamp system also includes a spring or other biasing device to hold the at least one set of clamps in an open position. In some embodiments, the clamp system also includes at least one stop to limit the opening of the at least one set of clamps. In some embodiments, the clamp system also includes an ROV connection adapted to connect the body to an ROV. In some embodiments, the clamshell device comprising a fairing. In some embodiments, the clamp system is mounted to a rack with at least one other clamp system. In some embodiments, the clamp system is attached to an umbilical. In some embodiments, the clamp system is attached to an umbilical, the umbilical attached to a subsea buoyancy device, the subsea buoyancy device adapted to isolate the clamp system from surface heave.
In one embodiment, there is disclosed a method of remotely installing a clamshell device having a longitudinal axis around an element, using a clamp system comprising at least one clamp with a cam surface, the method comprising positioning the clamp system adjacent to the element wherein the clamp system carries the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices; moving the clamp system to position the clamshell device around the element; moving the clamp system to engage the cam surface with the element to close the clamshell device around the element; and securing the device in position around the element. In some embodiments, the clamp system may be mounted on a rack with at least one other clamp system, the method further comprising repeating the positioning, moving, moving and securing with the at least one other clamp system. In some embodiments, the clamshell device installed is selected from a fairing, a shroud, an ultra-smooth sleeve, and a strake. In some embodiments, the clamshell device installed is selected from a flotation module and a collar.
Referring now to FIG. 1, in one embodiment of the invention, clamp system 3900 is illustrated, which could be used to install collars, strakes, fairings, shrouds, sleeves, or other devices onto an element, such as a substantially cylindrical member or an I-beam.
Clamp system 3900 includes clamp 3904, which is mounted to body 3902 by pivot 3912 and clamp 3906 by pivot 3914. Body 3902 includes stop 3916 and stop 3918, which are adapted to keep clamp 3904 and 3906 from opening too wide. Clamp 3904 includes cam surface 3920 and engaging surface 3924. Clamp 3906 includes cam surface 3922 and engaging surface 3926. Spring 3910 acts to bias clamp 3904 and clamp 3906 in an open position, as illustrated in FIG. 1. Spring 3910 could also be a bungee cord, an elastic member, or other arrangement as are known in the art. Element 3908 may be positioned within the opening of clamp 3904 and clamp 3906.
Referring now to FIG. 2, in some embodiments of the invention, body 3902 has been advanced in the direction of the arrow toward element 3908, so that cam surface 3920 and/or cam surface 3922 engage element 3908. As body 3902 is further advanced, element 3908 exerts a force on cam surface 3920, which pivots clamp 3904 towards a closed position about pivot 3912. Similarly, element 3908 exerts a force on cam surface 3922, which acts to pivot clamp 3906 towards a closed position about pivot 3914. This pivoting of clamp 3904 and clamp 3906 acts to close the clamps, and move engaging surface 3924 closer to engaging surface 3926. A sufficient force must be exerted on body 3902 in the direction of arrow to overcome the biasing force provided by spring 3910 and close clamps 3904 and 3906.
Referring now to FIG. 3, in some embodiments of the invention, body 3902 has been fully advanced towards element 3908, so that engaging surface 3924 is touching engaging surface 3926. Clamp 3904 and clamp 3906 are fully closed about element 3908.
As body 3902 is withdrawn from element 3908, spring 3910 acts to open clamps 3904 and 3906, by pivoting clamp 3904 about pivot 3912, and by pivoting clamp 3906 about pivot 3914. This pivoting continues until clamp 3904 encounters stop 3916, and clamp 3906 encounters stop 3918.
Referring now to FIG. 4, in some embodiments of the invention, there is illustrated a system 3900 for installing an apparatus about element 3908. System 3900 includes top clamp 3906, and bottom clamp 3907, which are pivotally connected to body 3902 by pivot 3914 and pivot 3915. Support arm 3932 is also pivotally connected to body 3902. ROV connection 3930 is provided, which may be used to connect body 3902 to an ROV (not shown). In operation, body 3902 is advanced towards element 3908, for example by an ROV, so that clamp 3906 and clamp 3907 engage element 3908, clamp 3906 and clamp 3907 close about element 3908. Similarly support arm 3932 may close about element 3908.
Referring now to FIG. 5, in some embodiments of the invention, a system 3900 for installing an apparatus about element 3908 is illustrated. System 3900 includes body 3902, which is connected to clamp 3906 by pivot 3914. In operation, body 3902 may be advanced towards element 3908, for example with an ROV. As clamp 3906 engages element 3908, clamp 3906 closes about element 3908.
Referring now to FIG. 6, in some embodiments of the invention, there is illustrated a top view of system 4000 installing clamshell device 4050 about element 4008. System 4000 includes body 4002 which is connected to clamp 4004 and clamp 4006. Clamp 4004 is pivotally connected to body 4002 by pivot 4012. Clamp 4006 is pivotally connected to body 4002 by pivot 4014. Stop 4016 and stop 4018 keep clamp 4004 and clamp 4006 from opening too far. Spring 4010 acts to bias clamps 4004 and clamp 4006 in the open position, as shown in the figure. As body 4002 is advanced in the direction of the arrow, cam surfaces 4020 and 4022 engage element 4008, which serve to close clamp 4004 and clamp 4006 about element 4008, which installs clamshell device 4050 about element 4008. Connector 4040 and connector 4042 are provided to anchor clamshell device 4050 to engaging surface 4024 and engaging surface 4026, respectively. Release 4044 is provided to disengage connectors 4040 and 4042, at the appropriate time, so that clamshell device 4050 may be released from system 4000. In operation, an ROV may engage release 4042 to release connectors 4040 and 4042. Suitable connectors 4040 and 4042 include pins, bolts, male-female connectors, groves, and other connectors as are known in the art.
Referring now to FIG. 7, in some embodiments of the invention, there is illustrated system 4000 installing clamshell device 4050 about element 4008. Body 4002 has been moved towards element 4008 to engage cam surfaces 4020 and 4022, to rotate clamp 4004 about pivot 4012, and to rotate clamp 4006 about pivot 4014. Closing clamp 4004 and clamp 4006 forces engaging surface 4024 towards engaging surface 4026. Between engaging surfaces 4024, 4026 is tail 4054 of clamshell device 4050. Tail 4054 is held together by connector 4052. Suitable connectors 4052 include rivets, screws, bolts, adhesives, male-female connectors, heat welds, adhesives, and other connectors as are known in the art.
Referring now to FIG. 8, in some embodiments of the invention, body 4002 has been moved away from element 4008, leaving behind clamshell device 4050 that has been installed about element 4008. Clamshell device 4050 includes tail portion 4054, which is held together by connector 4052, as body 4002 moves away from element 4008 in the direction of the arrow, clamp 4004 and clamp 4006 open, by pivoting about the pivots, due to the biasing force provided by spring 4010. Clamp 4004 opens as far as stop 4016, and clamp 4006 opens as far as stop 4018.
Referring now to FIG. 9, in some embodiments of the invention, system 4100 is shown for installing clamshell devices about an element. System 4100 includes clamp system 4102, clamp system 4104, and clamp system 4106, which are releasably connected to rack 4108. ROV 4110 is provided, which may release clamp system 4102, 4104, and/or 4106 from rack 4108, to install a clamshell device about an element.
Referring now to FIG. 10, in some embodiments, system 4200 is illustrated for installing a clamshell device about element 4220. System 4200 includes rack 4208, which may hold a plurality of clamp systems. Rack 4208 is connected by umbilical 4214 to subsurface buoyancy module 4216, which may serve to isolate system 4200 from water surface heave. Buoyancy module 4216 is connected by umbilical 4212 to surface structure 4222, which may be connected to element 4220. ROV 4210 may or may not be connected to umbilical 4214. In operation, ROV 4210 retrieves a clamp system from rack 4208, and installs the a clamshell device connected to the clamp system about element 4220, then deposits the used or empty clamp system back on rack 4208 and may retrieve another clamp system from rack system 4208 and install the a clamshell device connected to the clamp system about element 4220. This process may be continued until all the desired apparatus have been installed about element 4220, and/or until the capacity of rack 4208 is finished, at which time rack 4208 may be reloaded at surface structure 4222 or at another suitable location.
Although any clamshell device is believed to be suitable for use in the invention, in some embodiments of the invention, a clamshell device is utilized that includes a locking mechanism that will allow the system to lock the clamshell device around an element upon installation. The ends of the clamshell device may be outfitted with a mating locking mechanism that locks upon contact. Some examples of such locking mechanisms include male-female connectors, rivets, screws, adhesives, welds, and/or other connectors as are known in the art.
While the system has been described as being used in aquatic environments, that embodiment or another embodiment of the invention may also be used for installing clamshell devices on elongated structures in atmospheric environments with the use of an apparatus such as a crane.
While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the invention, including all features which would be treated as equivalents thereof by those skilled in the art to which this invention pertains.

Claims

1. A clamp system for remotely installing a clamshell device around an element, the clamp system comprising:

a body; and

at least one set of clamps supported by the body, the set suitable for holding and releasing the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices,

wherein at least one clamp comprises a cam surface adapted to engage the element and close the clamp about the element.

2. The clamp system of claim 1, wherein the at least one set of clamps comprises a first clamp comprising a first cam surface, and a second clamp comprising a second cam surface.

3. The clamp system of claim 1, wherein the body has a top and a bottom, wherein the at least one set of clamps is comprised of a first set of clamps and a second set of clamps, wherein the first set of clamps is supported by the top of the body and the second set of clamps is supported by the bottom of the body.

4. The clamp system of claim 1, wherein there are at least two sets of clamps.

5. The clamp system of claim 1, wherein the at least one set of clamps holds the clamshell device.

6. The clamp system of claim 1, wherein the body has a taller first height and is collapsible to a shorter second height for holding shorter devices or for storage of the clamp system.

7. The clamp system of claim 1, wherein at least one clamp comprises at least one nipple, pin, screw, bolt, nail, adhesive, or other type of connector for anchoring the clamshell device to the set of clamps.

8. The clamp system of claim 7, further comprising a release adapted to release the at least one nipple, pin, screw, bolt, nail, adhesive, or other type of connector so the clamshell device is not anchored to the set of clamps.

9. The clamp system of claim 1, wherein a plurality of clamps comprises a cam surface.

10. The clamp system of claim 1, wherein each clamp comprises a cam surface.

11. The clamp system of claim 1, further comprising a spring or other biasing device to hold the at least one set of clamps in an open position.

12. The clamp system of claim 1, further comprising at least one stop to limit the opening of the at least one set of clamps.

13. The clamp system of claim 1, the body further comprising an ROV connection adapted to connect the body to an ROV.

14. The clamp system of claim 1, the clamshell device comprising a fairing.

15. The clamp system of claim 1, the clamp system is mounted to a rack with at least one other clamp system.

16. The clamp system of claim 1, wherein the clamp system is attached to an umbilical.

17. The clamp system of claim 1, wherein the clamp system is attached to an umbilical, the umbilical attached to a subsea buoyancy device, the subsea buoyancy device adapted to isolate the clamp system from surface heave.

18. A method of remotely installing a clamshell device having a longitudinal axis around an element, using a clamp system comprising at least one clamp with a cam surface, the method comprising:

positioning the clamp system adjacent to the element wherein the clamp system carries the clamshell device selected from the group consisting of vortex-induced vibration reduction devices and drag reduction devices;

moving the clamp system to position the clamshell device around the element;

moving the clamp system to engage the cam surface with the element to close the clamshell device around the element; and

securing the device in position around the element.

19. The method of claim 18, wherein the clamp system may be mounted on a rack with at least one other clamp system, the method further comprising:

repeating the positioning, moving, moving and securing with the at least one other clamp system.

20. The method of claim 18, wherein the clamshell device installed is selected from a fairing, a shroud, an ultra-smooth sleeve, and a strake.

21. The method of claim 18, wherein the clamshell device installed is selected from a flotation module and a collar.