Subsea system for seabed operations

Abstract

Methods and systems relate to seabed operations, such as well intervention or capping, involving subsea equipment and subsea handling of the equipment, which may be associated with hydrocarbon wells or pipelines. A subsea system submerges during deployment and is landed on the seabed. The system may include a suspension assembly coupled to a frame structure for carrying equipment used in the operations. The deployment of the system may include deploying the frame structure with the equipment from a floating vessel connected to an anchored tether and moving the frame structure under water along the tether toward where anchored and the location for the seabed operations.

1 . A subsea system for seabed operations, comprising:
 a frame structure;   buoyancy members attached to the frame structure for submergence of the system and controllable to set submerged weight of the system on the seabed; and   a suspension assembly coupled to the frame structure for carrying equipment used in the operations and moveable by the suspension assembly relative to the frame structure.   
     
     
         2 . The subsea system according to  claim 1 , wherein the suspension assembly is operable via an umbilical line connecting the subsea system to a floating vessel. 
     
     
         3 . The subsea system according to  claim 1 , further comprising jack-up legs extendable from the frame structure for supporting the submerged weight of the system on the seabed. 
     
     
         4 . The subsea system according to  claim 1 , wherein the equipment is movable by the suspension assembly in vertical and horizontal directions relative to the frame structure. 
     
     
         5 . The subsea system according to  claim 1 , wherein the equipment is movable by the suspension assembly in a vertical direction and perpendicular horizontal directions relative to the frame structure. 
     
     
         6 . The subsea system according to  claim 1 , wherein the suspension assembly includes: parallel rails moveable in an up and down direction relative to the frame structure; a cross bar spanning the rails and moveable along the rails; and a hoist coupled to the equipment and moveable along the cross bar. 
     
     
         7 . The subsea system according to  claim 1 , wherein the equipment is movable by the suspension assembly in vertical, horizontal and rotational directions relative to the frame structure. 
     
     
         8 . The subsea system according to  claim 1 , wherein the equipment is movable by the suspension assembly in vertical, horizontal, rotational and angular directions relative to the frame structure. 
     
     
         9 . The subsea system according to  claim 1 , wherein lift provided by the buoyancy members is variable to adjust for weight of the equipment needed to be carried. 
     
     
         10 . The subsea system according to  claim 1 , wherein the frame structure has an open side to enable the system to be moved sideways into position around an object on the seabed for the operations. 
     
     
         11 . The subsea system according to  claim 1 , wherein the equipment includes at least one of a well capping stack and a well containment stack. 
     
     
         12 . A method of operating on a seabed with a subsea system, comprising:
 submerging the system including a frame structure;   adjusting buoyancy members attached to the frame structure for the submerging and for setting submerged weight of the system on the seabed; and   controlling a suspension assembly coupled to the frame structure in order to move equipment carried by the system relative to the frame structure for operational positioning of the equipment over the seabed.   
     
     
         13 . The method according to  claim 12 , wherein the controlling of the suspension assembly is via an umbilical line connecting the subsea system to a floating vessel. 
     
     
         14 . The method according to  claim 12 , further comprising extending jack-up legs from the frame structure to support the submerged weight of the system on the seabed. 
     
     
         15 . The method according to  claim 12 , wherein the controlling of the suspension assembly moves the equipment in vertical and horizontal directions relative to the frame structure. 
     
     
         16 . The method according to  claim 12 , wherein the equipment is movable by the suspension assembly in a vertical direction and perpendicular horizontal directions relative to the frame structure. 
     
     
         17 . The method according to  claim 12 , wherein the suspension assembly includes:
 parallel rails moveable in an up and down direction relative to the frame structure; a cross bar spanning the rails and moveable along the rails; and a hoist coupled to the equipment and moveable along the cross bar.   
     
     
         18 . The method according to  claim 12 , wherein the controlling of the suspension assembly moves the equipment in vertical, horizontal and rotational directions relative to the frame structure. 
     
     
         19 . The method according to  claim 12 , wherein the system moves in a horizontal direction into position around an object by an open side of the frame structure receiving the object on the seabed and over which the equipment operates. 
     
     
         20 . The method according to  claim 12 , wherein the equipment includes at least one of a well capping stack and a well containment stack.