Hydraulic and earth engineering – Marine structure or fabrication thereof – With anchoring of structure to marine floor
Reexamination Certificate
2003-03-28
2004-02-03
Lee, Jong-Suk (James) (Department: 3673)
Hydraulic and earth engineering
Marine structure or fabrication thereof
With anchoring of structure to marine floor
C405S195100, C405S172000, C405S226000, C114S296000
Reexamination Certificate
active
06685396
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to mooring line connections for subsea operations, particularly for suction anchor pile moorings. More particularly, this invention concerns a wire socket connector mechanism which facilitates subsea connection and reconnection of mooring lines of semi-submersible drilling rigs, production and drilling platforms and the like to suction anchor piles and other anchor devices. This invention also concerns deployment and installation of suction anchor piles and a mooring wire assembly with retrieval buoys and sling on one of its ends. The invention also concerns addition of buoys to mooring wire sections and connecting the mooring wire to a vessel to be moored. The procedure also concerns the mooring wire, buoy recovery, wire retrieval and suction anchor pile recovery and a procedure for recovering mooring wires and other apparatus.
2. Description of the Prior Art
Present procedures for installing subsurface anchors and establishing mooring the connection between the anchors and a semisubmersible drilling rig has required the presence of two service vessels, one an anchor handling vessel equipped with an A-frame type hoist for transporting the anchor and for lifting the anchor. The second service vessel is used to pull the hoisted anchor from the anchor handling vessel and to assist the anchor handling vessel in deployment of the anchor. When a large A-frame type hoisting mechanism is utilized for lifting the anchor from the anchor handling vessel, particularly in rough sea conditions, the heavy and bulky anchor and its peripheral equipment may swing to and from and may strike and damage other equipment in the immediate vicinity of the A-frame type hoisting mechanism. Additionally, since personnel will typically be required to ascend the A-frame type hoisting mechanism, such as to string wire rope and conduct other activities, the heavy swinging load of an anchor that is supported by the hoist constitutes and the movement of the A-frame hoist along with the vessel present significant hazards to the safety of workers whether present on the deck of the vessel or on the A-frame hoist or in the rigging of the hoist. It is desirable therefore to provide a system for transportation and deployment of subsea anchors and mooring lines which does not constitute a safety hazard for workers. It is also desirable to provide a system for transportation and deployment of subsea anchors and mooring lines and which minimizes the potential for damage to the vessel and its equipment even under circumstances where the sea conditions are rough during anchor deployment and recovery and during deployment and recovery of mooring lines. It is also desirable to provide a system for the handling, deployment and recovery of subsea anchors and installation and recovery of mooring lines which effectively minimizes the cost of stationing and mooring a semisubmersible vessel such as a drilling rig for well drilling operations.
Another significant disadvantage of using two service vessels for anchor transportation, handling and deployment is simply the duplication of costs when two vessels are utilized rather than a single vessel. It is desirable therefore to provide a system, utilizing a single anchor handling vessel, which is capable of transporting, deploying and retrieving subsea anchors in deep water conditions and is also capable of accomplishing connection and disconnection of mooring lines to permit drilling vessels to be quickly and efficiently stationed and restationed, thus conserving not only service vessel time and consequent cost but also conserving drilling vessel time and consequent cost.
The common feature of the present invention is the installation of a mooring anchor without the mooring line attached at the time of deployment and embedment in the sea bottom. Prior to the invention of the subsea connector shown in
FIGS. 21-25
hereof it was not possible to install an anchor in deeper water without the mooring line being attached to the anchor at the time of deployment. Heretofore, there has been no practical means of connecting a mooring line to an anchor embedded in the sea bottom in water depths that could not be manually accessed.
There is considerable advantage in being able to install mooring anchors without the mooring line attached. Several styles of advanced high holding power anchors for use in deeper water depths need to be deployed and embedded with a deployment line that has an attachment point apart from the preferred point of attachment of the mooring line. Previously, it had been necessary to deploy such anchors with both a deployment line extending from the principal deployment vessel and a separate mooring line extending from a second deployment vessel in order to prevent the two lines from becoming entangled with one another. The requirement for the use of two anchor handling and deployment vessels has added considerable cost and logistical difficulty to the anchor and mooring system deployment process. The method of mooring set forth herein is designed to specifically avoid this difficulty. In vessel anchoring situations such as is disclosed in U.S. Pat. No. 4,347,012 of Glidden the basic anchor base structure “A” must be deployed and installed at the sea bed with the pull line “P” attached or by threading the pull line P about the pulleys
18
and
19
and through the side opening
25
after the anchor base has been installed. While this activity can be accomplished in shallow water conditions, such as by a diver, it cannot be accomplished when water depth exceeds the working depth of divers. Thus, for deep water anchor deployment and installation, the anchor system of Glidden would require the use to two vessels, one vessel to handle the anchor base and another vessel to manipulate the pull line and prevent rotation of the anchor base due to cable unwinding during deployment and to thus keep the pull line from tangling with the anchor deployment line. The present invention is designed to promote anchor deployment with a single anchor handling and without any line being attached other than the anchor deployment line. Consequently, wound cable may be used for anchor deployment and anchor rotation by cable unwinding during deployment does not detract from the deployment procedure, since no cable fouling can be caused by anchor rotation. The present invention permits efficient single vessel, single line anchor deployment and also facilitates simple and efficient deployment line disconnection and mooring line connection via the use of ROVs. Later, when vessel mooring is no longer needed, the present invention also facilitates mooring line disconnection and anchor retrieval, again through the use of a single vessel and a single lifting line which permits rotation of the anchor during recovery from the sea bed.
There are several principal features of the mooring method of the present invention that prove to be practical and advantageous, the most simple of which is the deployment of the anchor with a single line from a single vessel with no mooring line attached as shown in
FIGS. 14 and 15
. Once the anchor is embedded, the mooring line is attached as shown in
FIG. 16
by the same or another vessel and laid on the sea bed or attached to a buoy which can be retrieved later, or the mooring line is attached to the anchor at some later date. This method provides the most efficient installation of the anchor and the most flexible arrangement for mooring line attachment to the anchor and connection to the marine structure to be moored.
The present invention envisions the use of Remote Operated Vehicles, called ROV's to operate the connector that connects the mooring line to the installed anchor. In fact, the connector is specifically designed to handle the mooring loads and be operated by the ROV. As such, the connector is a unique invention and this method of mooring that it enables is also a unique invention.
SUMMARY OF THE INVENTION
It is a principal feature of the present invention to pro
Andrews & Kurth LLP
Jackson James L.
Lee Jong-Suk (James)
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