Vertical Installation of an Elongated Process Unit

Abstract

This invention relates to a method for installation of an elongate process unit ( 4 )on the seabed, said process unit ( 4 ) to be handled comprising a first process unit end and a second process unit end. A method of retrieving an elongate process unit ( 4 ) from the seabed is also provided. Further, this invention relates to a receptor apparatus for use in a process unit handling operation, such as a process unit installation or retrieval operation.

1 . A method for installation of an elongate process unit on the seabed, in which said process unit has a first process unit end and a second process unit end, characterized in that said method comprises the following steps:
 a) preparing and moving said process unit to a position in which it is ready for being launched from a vessel and lowered through the sea with its longitudinal axis in a generally vertical orientation;   b) launching said process unit from said vessel;   c) lowering said process unit through the sea surface, the splash zone and further down to a deployment site at the seabed;   d) after said process unit lowering step c), entering said first process unit end into a receptor device for said first process unit end, so as to temporarily form a lower end of said first process unit end, the receptor device being located on the seabed or on a module foundation for said process unit at the seabed;   e) completing said process unit entry in said receptor device and retaining said first process unit end in place in said receptor device; and   f) lowering said second process unit end so as to bring the process unit as a whole from the generally vertical orientation to a generally horizontal orientation on the seabed or on said module foundation for said process unit, said first process unit end remaining supported by said receptor device, so as to form a fulcrum for said first process unit end, thus facilitating lowering of said second process unit end, and   g) deploying said process unit at the deployment site.   
   
   
       2 . Method according to  claim 1 , characterized in that said process unit entry step d) further comprises the step of:
 guiding said process unit to said receptor device before entering said first process unit end of said process unit into said receptor device.   
   
   
       3 . Method according to  claim 1 , 
     characterized in that said preparation and moving step a) and said launching step b) further include the following steps:
 moving and guiding said process unit towards the stern end of said vessel, said first process unit end facing said stern end of said vessel; 
 launching said first process unit end over a stern roller located at said stern end of said vessel. 
 
   
   
       4 . Method according to  claim 3 , characterized in that said process unit moving and guiding step is accomplished by conveying said process unit to said stern end of said vessel by means of a vessel crane or vessel winch, preferably having a heave compensator, the vessel crane or vessel winch controlling a vessel wire system which is attached to said process unit, so as to safely retain and guide said process unit. 
   
   
       5 . Method according to  claim 1 , characterized in that a receptor device is arranged on said vessel, and that said preparation and moving step a) and said launching step b) further include the following steps:
 entering said first process unit end into said receptor device for said first process unit end so that said first process unit end engages said receptor device, so as to temporarily form a lower end of said first process unit end;   completing said process unit entry in said receptor device and retaining said first process unit end in place in said receptor device, so as to form a fulcrum for said first process unit end;   lifting said second process unit end while said first process unit end remains supported by said receptor device, thus facilitating lifting of said second process unit end so as to bring the longitudinal axis of said process unit to a generally vertical orientation;   moving said process unit in said generally vertical orientation to a position in which it is ready to be launched into the sea; and   launching said process unit with its longitudinal axis in a generally vertical orientation into the sea.   
   
   
       6 . Method according to  claim 1 , characterized in that said preparing and moving step a) further comprises the step of:
 transferring said process unit from a transport frame to a vessel deck on said vessel.   
   
   
       7 . Method according to  claim 1 , characterized in that a framework including one or more process unit mating pins is attached to said first process unit end of said process unit, so that said process unit entry step d) further includes the following step:
 guiding said first process unit end into engagement with said receptor device by means of said one or more process unit mating pins being brought into engagement with said receptor device.   
   
   
       8 . Method according to  claim 1 , characterized in that said process unit includes at least two launch beams for facilitating generally horizontal movement of said process unit and for providing support for said process unit on the seabed, on said module foundation, on a process subsea skid, said vessel deck, or on said transport frame on said vessel deck. 
   
   
       9 . Method according to  claim 1 , characterized in that said completing and retaining step e) further includes the following step:
 locking and retaining said first process unit end of said process unit in place in said receptor device by means of a lock pin, so as to retain said one or more process unit mating pins included in said frame-work attached said first process unit end of said process unit in said receptor device; said lock pin preferably being spring loaded and ROV releasable.   
   
   
       10 . Method according to  claim 1 , 
     characterized in that
 said method further comprises the step of:
 keeping control of said second process unit end of said process unit by means of said vessel wire system including a lowering wire from said vessel crane or vessel winch on said vessel; 
 
 said process unit lowering step c) further includes the step of
 positioning said vessel generally above said receptor device in the sea and lowering said process unit in the sea with its longitudinal axis in a generally vertical orientation down to said receptor device; 
 
 said process unit end lowering step f) further includes the step of
 positioning said vessel so that the weight of said process unit is gradually transferred to said lowering wire, so as to start lowering of said second process unit end towards the seabed or said module foundation about said fulcrum formed by said first process unit end engaging said receptor device, 
 moving said vessel to a position so that an axial force component of the tension generated by said process unit in said lowering wire is directed towards said receptor device; so that said axial force component is generally parallel with the longitudinal, central axis of said process unit; and so that transversal force components of said force in said lowering wire from said second process unit end of said process unit to said vessel are reduced or minimized; 
 
 
     thus retaining said first process unit end in engagement with said receptor device, and reducing or minimizing the risk of disengagement of said first process unit end from said receptor device. 
   
   
       11 . Method according to  claim 1 , characterized in that
 said process subsea skid, or said transport frame or similar, includes
 guide and cradle arranged for supporting the load of said process unit to said module foundation or said transport frame; 
 one or more, preferably two pairs of wedges being adjustable in order to align said process unit on said process subsea skid or said transport frame, so as to bring the longitudinal axis of said process unit to the generally same level as said receptor device engaging said first process unit end of said process unit, thus relieving the load of said process unit from said receptor device to the module foundation; and that 
   said process unit  4  includes a process unit saddle arranged for transferring the load of said process unit to said guide and cradle.   
   
   
       12 . Method according to  claim 1 , characterized in that said wire system on said vessel includes
 one or more launch wires, extending from said vessel winch or a separate winch via a snatch block for each launch wire to an attachment location on said vessel; said snatch block being located at the stern end of said vessel;   a launch control-wire with bridle connected to a separate winch;   a lowering wire connected to a separate winch and to said second process unit end of said process unit.   
   
   
       13 . Method according to  claim 1 , characterized in that after the deployment step g), it further comprises the step of:
 h) loosening or removing said receptor device from said first process unit end.   
   
   
       14 . Method according to  claim 1 , characterized in that said elongate process unit is a horizontal gravitational separator. 
   
   
       15 . Method according to  claim 1 , characterized in before said preparation and moving step a) and said launching step b):
 placing a receptor device, including a transport frame, with the process unit in engagement with said receptor device on the flatbed of a lorry, truck, railway carriage or other wheel carriage,   transporting said receptor device with said process unit to said vessel, and   lifting said receptor device with said process unit onto said vessel.   
   
   
       16 . A method of retrieving an elongate process unit from the seabed, in which said process unit has a first process unit end and a second process unit end, characterized in that said method comprises the following steps:
 a) preparing said process unit for removal from a deployment site;   b) lifting said second process unit end from the seabed or from a module foundation for said process unit, said first process unit end being retained in a receptor device, thus temporarily forming a lower end of said first process unit end, and so as to bring the longitudinal axis of said process unit as a whole from the generally horizontal orientation to a generally vertical orientation; said first process unit end of said process unit and said receptor device forming a fulcrum for said first process unit end, thus facilitating lifting of said second process unit end;   c) disengaging said first process unit end from said receptor device;   d) hauling said process unit from said deployment site at the seabed, up through the sea, the splash zone and the sea surface to a vessel;   e) bringing said process unit aboard said vessel, and   g) preparing and moving said process unit to a generally horizontal position onboard said vessel, in which it is sea-fastened and ready for being transported on said vessel.   
   
   
       17 . Receptor apparatus for use in a process unit handling operation, in which the process unit to be handled comprises a first process unit end and a second process unit end, characterized by the following features:
 a receptor device arranged for receiving and engaging a first process unit end, and further arranged for receiving and supporting the load of said process unit, and   said receptor device being arranged for receiving and engaging said first process unit end, and said receptor device further being arranged for retaining said first process unit end in place in said receptor device and providing a fulcrum for said first process unit end during handling of said second process unit end and being adapted to take up a substantial part of the weight of the process unit when the process unit as a whole is transferred between a substantially vertical position and a substantially horizontal position.   
   
   
       18 . Receptor apparatus for use in a process handling operation, in which the process unit to be handled comprises a first process unit end and a second process unit end, characterized by the following features:
 a receptor device arranged for receiving and engaging a first process unit end, and further arranged for receiving and supporting the load of said process unit,   said receptor device being arranged for receiving and engaging said first process unit end, and said receptor device further being arranged for retaining said first process unit end in place in said receptor device and providing fulcrum for said first process unit end during handling of said second process unit end and being adapted to take up a substantial part of the weight of the process unit when the process unit as a whole is transferred between a substantially vertical position and a substantially horizontal position,   said receptor device comprises two or more receptor brackets in a space apart arrangement, each receptor bracket having a receptor bracket guide; and that   said receptor bracket guides included in said receptor brackets are each arranged for receiving a process unit mating pin included in said framework which is attached to said first process unit end, so that said receptor brackets form support bearings for said process unit via said process unit mating pins when engaged with said first process unit end of said process unit; thus forming a fulcrum for said first process unit end of said process unit.   
   
   
       19 . Receptor apparatus for use in a process unit handling operation, in which the process unit to be handled comprises a first process unit end and a second process unit end, 
     characterized by the following features:
 a receptor device arranged for receiving and engaging a first process unit end, and further arranged for receiving and supporting the load of said process unit, 
 said receptor device being arranged for receiving and engaging said first process unit end, and said receptor device further being arranged for retaining said first process unit end in place in said receptor device and providing a fulcrum for said first process unit end during handling of said second process unit end and being adapted to take up a substantial part of the weight of the process unit when the process unit as a whole is transferred between a substantially vertical position and a substantially horizontal position, 
 a receptor cylinder in connection with said receptor, said receptor cylinder arranged for receiving and engaging said first process unit end, 
 two or more receptor bearings in a spaced apart arrangement for supporting the load of said process unit; each receptor bearing being provided with a receptor rotating pin so as to form a fulcrum for said receptor device. 
 said receptor and said receptor cylinder being arranged for receiving a process unit mating pin attached to said first process unit end of said process unit. 
 
   
   
       20 . Receptor apparatus according to  claim 17 , characterized in that said receptor device is arranged on a module foundation arranged for supporting said receptor device and the load from said process unit. 
   
   
       21 . Receptor apparatus according to  claim 17 , characterized in that said receptor device is arranged for receiving one or more process unit mating pins included in a framework being attached to said first process unit end of said process unit. 
   
   
       22 . Receptor apparatus according to  claim 21 , characterized in that
 said receptor device comprises two or more receptor brackets in a spaced apart arrangement, each receptor bracket having a receptor bracket guide; and that   said receptor bracket guides included in said receptor brackets are each arranged for receiving a process unit mating pin included in said framework which is attached to said first process unit end, so that said receptor brackets form support bearings for said process unit via said process unit mating pins when engaged with said first process unit end of said process unit; thus forming a fulcrum for said first process unit end of said process unit.   
   
   
       23 . Receptor apparatus according to  claim 17 , characterized in that said receptor device comprises
 a receptor arranged for receiving and engaging a first process unit end of a process unit,   a receptor cylinder in connection with said receptor, said receptor cylinder arranged for receiving and engaging said first process unit end,   a receptor dampening or yielding member located in said receptor cylinder; said receptor dampening member being arranged for receiving the load of said process unit and for dampening or minimizing the impact of the load of said process unit by said first process unit end on said receptor device,   two or more receptor bearings in a spaced apart arrangement on said module foundation; said receptor bearings being arranged for supporting the load of said process unit; each receptor bearing being provided with a receptor rotating pin so as to form a fulcrum for said receptor device,   each receptor bearing optionally being provided with a dampening pad, so as to dampen the impact when said receptor device receives and engages the load of said process unit and for assisting said dampening member in said receptor device in receiving and supporting this load,   said receptor and said receptor cylinder preferably being arranged for receiving a process unit mating pin of a framework attached to said first process unit end of said process unit.   
   
   
       24 . Receptor apparatus according to  claim 23 , characterized in that said receptor cylinder is provided with a rotational guide arranged for engaging a corresponding guide formation or shoulder on said process unit mating pin, so as to facilitate rotation of said process unit mating pin in said receptor cylinder. 
   
   
       25 . Receptor apparatus according to  claim 17  characterized in that
 it is located at the seabed, preferably on a module foundation at the seabed, and arranged for facilitating deployment or removal of a process unit on the seabed, or that   it is located on said vessel and arranged for facilitating launching of said process unit into the sea, for loading onto said vessel and for transport of said process unit on said vessel.   
   
   
       26 . Use of a receptor apparatus according to  claim 17  comprising
 handling of said first process unit end of said process unit so as to facilitate preparation aboard a vessel for launch of said process unit into the sea, or   handling of said first process unit end of said process unit so as to facilitate preparation of said process unit aboard a vessel for transport of said process unit; or   handling of said first process unit end of said process unit for deployment of said process unit onto said module foundation arranged at a deployment site at the seabed, or   handling of said first process unit end of process unit for removal of said process unit from said module foundation arranged at a deployment site at the seabed.