DEPLOYMENT OF CABLES FOR LANDING STRINGS

Abstract

Embodiments may generally take the form of a cable winch system installable within a riser on a landing string. In particular, one embodiment may take the form of a system having a tubular deployable within a riser and a cable winch deployable within a riser. The cable winch is configured to travel with the tubular as it is deployed within the riser.

Description

BACKGROUND

Generally, landing string systems are used during completion of offshore wells and are deployed into a drilling riser using an umbilical. The fluids, electrical power and communications services from the surface vessel or rig to the landing string are transmitted via this umbilical. As such, the umbilical includes hoses, electrical cables and communications cables. These landing string systems also may include a hydraulic power unit located on the surface support vessel. The umbilical is stored on a storage reel that is used to deploy the umbilical in the riser from the drilling rig. The umbilical is fed into the riser during deployments so that it can slide on parts of the rig as it is being deployed. The umbilicals are clamped onto the landing string tubular members during deployment as they cannot be deployed under tension due to the nature of their construction. Deploying and clamping the umbilical on the tubulars is a time consuming phase of the deployment operation and results in increased rig time. Additionally, locating the umbilical reel on the rig may present installation issues, many times requiring sheaves to be located in the tower to provide a path for the umbilical from the reel to the rig floor.

SUMMARY

Embodiments may generally take the form of a cable winch system installable within a riser on a landing string. In particular, one embodiment may take the form of a system having a tubular deployable within a riser and a cable winch deployable within a riser. The cable winch is configured to travel with the tubular as it is deployed within the riser.

Another embodiment may take the form of a method of providing subsea communications. The method includes securing a cable winch to a subsea landing string, securing a cable wound on the cable winch at a surface location and deploying the subsea landing string.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example landing string system with conventional hardware.

FIG. 2 illustrates a cable winch system deployable as part of the landing string system of FIG. 1.

DETAILED DESCRIPTION

A cable winch system is disclosed that may be installed on a landing string. The winch system contains a cable that is stored and deployed from the landing string, as it is lowered into the riser. In the system, no cable storage reel or winch on the surface is used. Additionally, the system may be implemented without sheaves and/or clamping on the tubulars during deployment, reduces occupied deck space, and helps prevent cable damage during deployment, subsea operations and retrieval of the landing string.

The disclosed cable winch system provides a hard wired connection that can function as a backup to an umbilical-less communication system or may be used as a primary communication mode. Transmission through the cable provides rapid communication between the landing string and the control system.

Turning to the drawings and referring initially to FIG. 1, a subsea test tree system 100 is illustrated. The system 100 may include surface components and subsurface component. For the sake of conciseness, not all the surface or subsurface components are described and/or illustrated. Additionally, the specific function of the components may not be discussed in detail, but would be understood and appreciated by those skilled in the art. In an actual implementation, more, fewer and/or different components may be used. As such, the system 100 is provided as an example context in which the cable winch system installed on a landing string may be implemented. The description herein should not be understood as limiting the applicability of the cable winch system to a particular context and/or system, however.

A wireline blow out preventer (BOP) 110 and a flowhead 120, may be located at, near or above the sea's surface. Additionally, hydraulic/electrical consoles 132 and a chemical injection skid 134 may be positioned on a rig floor 130 at, near or above the surface. Communication and control modules may be located on the rig floor as well and may be configured to communicate with and/or control subsea components.

Lubricator valves 140 may be located beneath the rig and within a riser 150. Tubing may extend within the riser 150 and through a subsea BOP stack 170, a subsea test tree 180 and below a mudline 190. One or more safety valves 192 may be located below the mudline along with drill stem testing (DST)/completion string components 194.

FIG. 2 illustrates the cable winch system 200 that may be implemented with the system of FIG. 1. The cable winch system 200 includes a winch 220 with a communications cable 208, such as a fiber optic or copper based communications cable. The winch 220 may be located subsea inside the riser 150. The cable 208 may be paid out under tension as the landing string is deployed. The cable diameter can be configured to have a size, such as approximately ⅜″ or less, to accommodate space restraints within the riser annulus. In other embodiments, the cable may be approximately ⅜″ or larger.

The cable 208 can be fixed on the rig floor 130 at a termination point 206. For example, the termination point 206 may be at or near a surface location such as at or near a rig's rotary table. This may help prevent cable damage due to rubbing on slips. Additionally, no overhead sheaves may be implemented to route the cable to the winch and not added deck space may be consumed by the winch. Relative motion between the cable and the riser or landing string tubular is reduced, and may be eliminated in some instances.

A master control station 202 may be communicatively coupled with the cable termination point 206. For example, in one embodiment, a jumper 204, such as an armored jumper, can be utilized to connect the cable termination point 206 to the master control station 202. The jumper is installed from the cable termination 206 using a connector to attach the jumper or the jumper can be an extension of the cable. The jumper is of sufficient length to account for the relative motions when the cable is clamped to the landing string tubular and the jumper may be flexible. The jumper cable (or cable extension) can include a connector which mates with a compatible receptacle on the Master Control Station 202. In some embodiments, a wireless communication link may be provided between the master control station 202 and the cable termination 206. In such embodiments, a communication node may be co-located with the cable termination 206. The communication node may take any suitable form and may include one or more antennas. Additionally, one or more transmitters/receivers and/or other components, such as signal processing components, may be co-located with the cable termination and/or the master control station. For example, a multiplexer, a filter, an amplifier and so forth each may be provided.

In one embodiment, the winch 220 may include a standard configuration with a grooved sleeved drum, level wind subassembly 211, slip rings 230 for communications and power and interface to the landing string controls 212 via a subsea jumper cable 210. The winch 220 can be electrically operated from the subsea test tree 180 (FIG. 1) or hydraulically powered from a subsea hydraulic power unit (HPU).

The winch 220 may be controlled automatically using tension controls that set a constant or variable tension at the winch. The tension control system 231 may automatically compensate for the amount of cable paid out during deployment into and out of the riser. This load keeps the cable taut so that it does not fall into the riser 150, snag on the riser or bird nest on the drum. The set tension allows the winch to pay out cable when tubulars 160 are lowered or pay in cable when tubulars are raised. Winch drum inertia may be mitigated to provide for proper tension control and operation. Further, the winch 220 can include a level wind system 211 to help spool cable onto the drum.

The subsea winch cable 208 may have a standard configuration with aramid fiber strength member over a water proof jacket containing the conductor(s) or may have a metal outer strength member. The conductors may be used for control signal and or power as required within the constraints of the cable diameter.

The cable 208 can include a tension termination to be connected at the rig floor or above (e.g., the termination point 206). This tension termination may be located at the surface end of the cable and is clamped off to a structural member on the rig floor or above. Because the rig is moving relative to the seafloor the winch compensates for the relative motion when the landing string is installed. To avoid the relative motion, after installation, a connection may be made by transferring the termination to a clamp on the landing string tubular.

Some embodiments may take the form of a method of deploying cable from a landing string as it is deployed. For example, once the equipment is placed on the rig, and as the landing string is deployed into the riser 150, the cable end is connected to the rotary. A guide roller assembly may be installed in the rotary when the landing string is in the riser to move the termination away from the rotary slips 240. A surface jumper 204, which connects the cable 208 to the master control station 202, is then connected to the cable safely.

As successive tubular strings are connected and the landing string is deployed in the riser 150, the subsea winch 220 automatically pays out cable 208 during deployment and maintains tension at the winch. When the cable 208 is fully deployed the cable may be connected to the landing string tubular so that any vessel motion does not affect the cable. In some embodiments, the jumper 204 is provided with slack to take vessel motion. In some embodiments, no topside swivel associated with the system is provided. As such, any rotation can be taken out by slack in the cable. Further, the winch 220 is configured to automatically pay in cable 208 during retrieval operations. Since there is not a requirement to attach the umbilical to the landing string tubulars during operations this method presents a time savings over existing techniques.

While various embodiments have been described herein with respect to a limited number of examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments and variations thereof can be devised which do not depart from the scope disclosed herein. Accordingly, the scope of the claims should not be unnecessarily limited by the present disclosure.

Claims

1. A system comprising:

a tubular deployable within a riser; and

a cable winch deployable within a riser, wherein the cable winch is configured to travel with the tubular as it is deployed within the riser.

2. The system of claim 1, wherein the cable spool dispenses cable as it is deployed within the riser.

3. The system of claim 2, wherein the cable is deployed under tension.

4. The system of claim 2, wherein the cable comprises at least one of a fiber optic cable or a copper based cable.

5. The system of claim 2, wherein the cable is terminated at or near a rig floor.

6. The system of claim 4, wherein a flexible jumper communicatively couples the cable with a surface control system.

7. The system of claim 4, wherein a flexible jumper communicatively couples the cable with a subsea control system.

8. The system of claim 3, wherein a hydraulic, electrical or hydroelectrical device provides tension.

9. The system of claim 8, wherein the hydraulic, electrical or hydroelectrical device is configured to compensate for relative motion between a rig at surface and the

10. The system of claim 1 further comprising a guide roller assembly installed in a rotary.

11. The system of claim 2, wherein the cable is approximately ⅜″ cable or less.

12. The system of claim 2, wherein the cable is approximately ⅜″ cable or greater.

13. The system of claim 1, wherein the cable winch comprises a level winding system.

14. A method of providing subsea communications comprising:

securing a cable winch to a subsea landing string;

securing a cable wound on the cable winch at a surface location; and

deploying the subsea landing string.

15. The method of claim 14 further comprising:

communicatively coupling the cable with subsea controls; and

communicatively coupling the cable with a master control system.

16. The method of claim 15, wherein a first jumper is coupled between a cable termination and the subsea controls and a second jumper is coupled between a cable termination at surface and the master control system.

17. The method of claim 14 further comprising clamping an end of the cable to a landing string tubular after installation to eliminate relative motion between the cable and the landing string.

19. The method of claim 14, further comprising providing tension to the cable as the landing string is deployed.

20. The method of claim 14, further comprising:

retrieving the landing string; and

winding cable onto the winch.