Pipeline freespan support

A method for providing support at a pipeline at a freespan location, comprising:

• providing a lower structure comprising:
• four round posts;
• two spaced mud mats on which the posts stand;
• first and second sheaths that fit around two of the posts, the first and the second sheaths being rotatable around the two round posts and translatable along the two round posts;
• two horizontal arms that are attached to the first and the second sheaths, respectively, so each horizontal arm is rotatable about the a corresponding post and translatable along the corresponding post;
• and
• third and fourth sheaths that fit around other two of the posts, the third and the fourth sheaths being translatable along the other two posts, the third and the fourth sheaths comprising teeth dimensioned to receive the first and the second horizontal arms, respectively;
• providing a upper structure comprising:
• four round legs connected to one another by a plurality of bracing members, wherein the posts of the lower structure is dimensioned to insert into the legs;
• and
• attachment points through which the upper structure can be lifted;
• placing the lower structure on a platform;
• lowering an upper structure onto the lower structure at an appropriate height, wherein the posts of the lower structure are inserted into the legs of the upper structure;
• locking the upper structure and lower structure together with first lock pins that inserted into first through holes in the legs and the posts to form an integrated structure;
• lowering the integrated structure over the pipeline at the freespan location, with the horizontal arms in open position, allowing the pipeline to pass through an opening between the two mud mats, and landing the integrated structure on an underwater floor;
• rotating the horizontal arms into the teeth of the third and the fourth sheaths;
• unlocking the upper structure from the lower structure by removing the first locking pins, retrieving the upper structure to surface, and leaving the lower structure on the underwater floor;
• and
• lifting the horizontal arms until both arms are in contact with the pipeline and providing suitable support, and fixing the horizontal arms in the supporting position with second locking pins that insert into second through holes in the first and the second sheaths and the posts.