Deepwater completion installation and intervention system

A vessel, comprising:

• a deck;
• a planar grid coupled to and disposed above the deck, the grid having one or more lengthwise beams and one or more crosswise beams intersecting the lengthwise beams;
• and
• a rig configured to deploy apparatus for subsea hydrocarbon operations at a substantially horizontal angle with respect to the deck, wherein at least some of the apparatus are routed through pre-existing holes in at least the lengthwise beams or the crosswise beams of the grid before deployment.

A system, comprising:

• a vessel configured to deploy, from a planar grid coupled to and disposed above a deck of the vessel, apparatus for subsea hydrocarbon operations at a substantially horizontal angle with respect to the deck of the vessel, the grid having one or more lengthwise beams and one or more crosswise beams intersecting the lengthwise beams, wherein at least some of the apparatus are routed through pre-existing holes in at least the lengthwise beams or the crosswise beams of the grid before deployment;
• a buoyant tensioning system (BTS) for coupling to a subsea wellhead;
• and
• a buoyant horizontal riser (BHR) coupled between the BTS and the vessel for routing the apparatus between the vessel and the wellhead.