Patent Application
20140049399
1. Field of the Invention
This invention relates to subsea monitoring systems, in general, and systems and methods of visually indicating an engagement status of a submerged subsea connector which utilize voltage from the cathodic protection system for submerged subsea equipment as a power supply and/or voltage multiplier for a subsea position monitoring system, in particular.
2. Description of the Related Art
Subsea connectors can be utilized to provide upper section emergency disconnect package (“EDP”) to lower EDP section connections, blowout preventer (“BOP”) stack to wellhead connections, lower marine riser package (“LMRP”) to BOP stack connections, completion tree to wellhead connections, TPL/subsea template tiebacks, production riser assembly to subsea manifold connections, single point mooring to anchor base, and caisson completions and artificial island.
Various types of these connectors provide excellent bending in tensile load capabilities, field-proven hydraulically operated engagement, and metal-to-metal sealing. According to an emergency disconnect package implementation, the hydraulic actuators, often referred to as dogs, are typically located well within the frame structure of the emergency disconnect package, making visual verification of complete engagement generally impossible.
A standard technique for reducing corrosion of the metal items and surfaces of the EDP after deployment underwater equipment, which are prone to corrosion due to the electrolytic nature of the surrounding seawater, is to use cathodic protection (“CP”). A widely-used form of CP is the galvanic anode-type cathodic protection, in which a sacrificial metal surface is positioned proximate to the metal items to be protected. The sacrificial metal material is chosen which has a greater magnitude electrochemical potential than the item to be protected. Commonly used sacrificial metal materials include, for example, alloys of zinc, magnesium, and aluminum. When located subsea adjacent the metal components and surfaces to be protected, for example, the sacrificial metal material will be corroded instead of to the item being protected. Eventually, the sacrificial material will be corroded to such an extent that replacement of the sacrificial material is necessary.
Recognized by the inventor is that it would be desirable to provide a visual indication of positive engagement of them at a location outside the frame structure, sufficient to be perceived by a remote operated vehicle (“ROV”). Recognized by the inventor is the need for a system which provides electrical current to power small voltage devices such as, for example, solid-state signal lamps connected to the lower portion of a subsea emergency disconnect package, a subsea Christmas tree, or other similarly located subsea equipment, which provide measurements and/or visual position indications of dog engagement. Still further recognized by the inventor is that a tap into the main power system or an additional umbilical line to power search system would excessively complicate the emergency disconnect package and/or degrade its capabilities.
Also recognized by the inventor is that the cathodic protection system of the subsea emergency disconnect package equipment could be used as a galvanic cell to generate supply voltage or voltage multiplication for a small voltage/low-power minor device. Stated in an alternative manner, recognized by the inventor is that the protective potential or closed-circuit anode potential is used as a power supply for the small voltage/low-power devices including visual engagement status indicators.
In view of the foregoing, various embodiments of the present invention advantageously feature systems and methods that provide electrical current to power small voltage devices connected to the lower portion of a subsea system such as, for example, an emergency disconnect package, a lower marine riser package, a subsea Christmas tree or other similarly located subsea equipment, which provide measurements and/or visual position indications of one or more associated subsea components of the subsea equipment. Various embodiments are configured to use the cathodic protection system of the subsea equipment as a galvanic cell to generate supply voltage or voltage multiplication for a small voltage/low-power minor device. According to various embodiments, the protective potential or closed-circuit anode potential is used as a power supply for the small voltage/low-power devices.
Various embodiments of the present invention provide a power supply and/or voltage or current multiplication system which utilizes the voltage from the cathodic protection system for a submerged subsea system as a power supply and/or voltage multiplier source for a subsea monitoring system. Various embodiments of the power supply and voltage multiplication system negates a need to provide long and expensive electrical lines to supply small voltage minor devices. Various embodiments also negate the need to tap into a main subsea system electrical supply or that of an ROV, or the need to provide a mechanical system solution capable of providing such measurements or visual indication.
According to various embodiments, a subsea monitoring system can include a system for visually indicating an engagement status of a submerged subsea connector. More specifically, an example of an embodiment of a system for providing a visual indication of subsea connector engagement can include a measurement device or devices (e.g., piezoelectric device) positioned to provide at least a threshold level of voltage indicative of engagement of a locking or other connection mechanism (e.g., strain or position) for a submerged subsea connector, and a visual engagement status indicator assembly. The assembly can include a light emitting visual engagement status indicator positioned, for example, on an outside portion of a surrounding frame member to provide a visual indication corresponding to an engagement status of the connection mechanism provided by the piezoelectric device, and a power supply assembly configured to interface with portions of an adjacent cathodic protection system to provide supply power or voltage multiplication to the visual engagement status indicator. In an exemplary embodiment, a measurement device in the form of a piezoelectric device measures strain resulting from engagement of a connecting ring operably coupled to one or more hydraulic cylinders connected to an upper connector body assembly of an emergency disconnect package with one or more locking members (e.g., dogs) configured to engage one or more engagement recesses extending into an outer surface of a subsea connector for a lower portion of the emergency disconnect package. A threshold level of the strain can be used as a reference to indicate engagement of the one or more locking members with the one or more engagement recesses of the subsea connector.
According to an embodiment, the power supply assembly includes a switching circuit (e.g., incorporating a logical “AND”) configured to complete a circuit between a first element of the cathodic protection system defining an anode, and the visual engagement status indicator when the piezoelectric device provides a signal voltage having an amplitude exceeding a threshold voltage level. A first conductor extends from the piezoelectric device and is connected to a first terminal of the switching circuit, and a second conductor extends from the first element (anode) of the cathodic protection system. A visual engagement status indicator is electrically coupled to a second element of the cathodic protection system defining a cathode to emit a sufficient light level to be visually detected via a remotely operated vehicle when the piezoelectric device encounters a threshold level of strain or other movement, depending upon the type of visit electric device utilized and its positioning.
Embodiments of the present invention also include methods of visually indicating an engagement status of a submerged subsea connector or other component. An example of the method can include the steps of positioning a measurement device to provide a signal indicating positive engagement of a locking mechanism for a submerged subsea connector, positioning a visual engagement status indicator to provide a visual indication corresponding to an engagement status of the locking mechanism provided by the measurement device, and interfacing components of a power supply assembly with portions of a cathodic protection system adjacent the visual engagement status indicator to provide supply power or voltage multiplication to the visual engagement status indicator. The step of positioning a visual engagement status indicator can include electrically coupling the visual engagement status indicator to an element of the cathodic protection system defining a cathode to emit a sufficient light level to be visually detected via a remotely operated vehicle (“ROV”) when the measurement device encounters a threshold level of strain or other movement. The steps can also include measuring strain resulting from engagement an engagement surface of a locking member with a corresponding locking recess extending into an outer surface of a subsea connector for a lower portion of the emergency disconnect package. A threshold level of the strain indicates engagement of the engagement surface of the locking member with the locking recess portion of the subsea connector as a result of engagement of the locking member by a connecting ring operably coupled to one or more hydraulic cylinders connected to an upper connector body assembly of the emergency disconnect package. When the threshold level of strain it is met, the visual engagement status indicator can be “lit” to provide a visual indication visible to an ROV that the component is engaged.
So that the manner in which the features and advantages of the invention, as well as others which will become apparent, may be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only various embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it may include other effective embodiments as well.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. Prime notation, if used, indicates similar elements in alternative embodiments.
In view of the foregoing, various embodiments of the present invention advantageously feature systems and methods that provide electrical current to power small voltage devices connected to the lower portion of a subsea system such as, for example, an emergency disconnect package, a lower marine riser package, a subsea Christmas tree or other similarly located subsea equipment, which provide measurements and/or visual position indications of one or more associated subsea components of the subsea equipment. Various embodiments of the present invention provide a power supply and/or voltage or current multiplication system which utilizes voltage from the cathodic protection system for a submerged subsea system as a power supply and/or voltage multiplier source for a subsea monitoring system. According to various embodiments, the subsea monitoring system can include a system for visually indicating an engagement status of a submerged subsea connector.
The upper section 31 of the EDP is held in place by a set of hydraulic (hydraulically actuated) cylinders and/or upper connector dogs 41 slidably connected to an upper connector cam ring 42, which are engaged through actuation of a hydraulic piston 43, to cause an engagement surface 44 of the dogs 41, themselves typically pivotally connected to or interfaced with an upper subsea connector 45, to extend into and engage a recess 46 in the lower subsea connector 47 in the lower section 33 of the EDP 30. The dogs 41 function to connect the upper section 31 of the EDP 30 to the lower section 33 of the EDP 30. In the illustrated embodiment, the hydraulic piston 43 is connected to an upper connector body assembly 49 to provide such engagement mechanism. One or more upper connector stops 50 limit movement of the cam ring 42 and/or movement of dogs 41. The lower section 33 of the EDP 30 includes one or more lower connector pistons 51 connected to a lower connector lock ring 53 which includes an engagement surface 55, which engages surface 57 located on lower portion of dogs 41, which functions to lock dogs 41 in the engagement position with recess 46. According to an exemplary embodiment, subsea connector 45 is a sixteen inch HAR subsea connector.
At least one or more but typically a plurality of measurement devices 63 (only one shown) are positioned on a main structural element of or adjacent to the lower section connector 47 to provide position measurements based on the position or applied strain/stresses on the lower connector locking ring 53 resulting from engagement of engagement surface 55 of the locking ring 53 with the engagement surface 57 of the dogs 41. The measurement device or devices 63 are, however, typically positioned upon one of the lower connector pistons 51 or on a component positioned between the lower connector lock ring 53 and one or more of the lower connector pistons 51. The amount of strain or movement can provide an indication that the subsea connector 47 is properly positioned.
A corresponding plurality of visual engagement status indicators 71 (only one shown) are connected to an outer surface 73 of a medial or upper beam 75 of the multi-part frame 35. A conductor 77 connects between a corresponding one of the measurement devices 61 and the respective visual engagement status indicators 71. Also or alternatively, a second plurality of visual engagement status indicators 81 are connected to an outward facing surface 83 of a base portion 85 of the multi-part frame 35. A conductor 87 connects between a corresponding one of the measurement devices 63 and the respective visual engagement status indicator 81. Additional or alternative visual engagement status indicators 71, 81, can be connected around the multi-part frame to provide redundancy and/or assist a remote operating vehicle (“ROV”) in visually detecting its status.
According to an exemplary embodiment, the visual engagement status indicator or indicators 71 each include one or more light emitting diodes positioned to provide a visual signal indicating that the upper section subsea connector 45 is properly engaged atop the lower section connector 47. Similarly, the visual engagement status indicator or indicators 81 provide a visual signal indicating that the lower section connector 47 is properly engaged. Each visual engagement status indicator 71, 81, can be implemented as a basic cluster of one or more light emitting diodes positioned to provide a visual indication corresponding to the measurements provided by the measurement devices 61, 63. For example, with respect to the measurement devices 61, a threshold level of strain or position change provides a threshold level of voltage indicating engagement of the engagement surface 44 of dogs 41 in the corresponding locking recess or recesses 46. With respect to the measurement devices 63, a threshold level of strain or position change similarly provides the requisite threshold level of voltage. Note, other forms of light emitting devices as known to those of ordinary skill in the can be utilized.
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Rather than suffer the complication of tapping into the main supply power or running a separate conductor to power each visual engagement status indicator 71, 81, according to one or more embodiments, the visual engagement status indicators 71, 81, can be electrically interfaced with the frame surface 95 and with the sacrificial metal panel or bars 91. In an exemplary embodiment, multiple low voltage, low amperage visual engagement status indicator “assemblies” 71, 81, are connected directly to an exposed outward facing surface 95 of the frame 35 to interface with the “cathode” and a small conductor extends to the nearest sacrificial metal panel or bar 93 to interface with the “anode” to leech power produced by the cathodic protection system.
In the drawings and specification, there have been disclosed a typical preferred embodiment of the invention, and although specific terms are employed, the terms are used in a descriptive sense only and not for purposes of limitation. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification. For example, although described as providing power to visual engagement status indicators 97, one of ordinary skill in the art would understand that the scope of the invention extends to utilization of the potential between anode and cathode of a cathodic protection system (working as a galvanic cell) to supply power to other small voltage devices.
