ROV DEPLOYED TREE CAP FOR A SUBSEA TREE AND METHOD OF INSTALLATION

A lightweight ROV deployable tree cap (28) for deployment on a subsea production hub (10) of a subsea try. A tree cap (28) has a lightweight body (30) with parallel planar sides and including suitable openings and slots for mounting on the various operating elements. A seal plate structure (64) includes a piston (66) connected to a seal plate (68) having a pair of downwardly projecting tubular seal members (70, 72) for fitting within the production bore (13) and annulus bore (15) o f the tree hub (10) in a sealed landed position. Fluid pressure is applied to fluid line (96) to urge piston (66) and seal plate (68) downwardly into sealing landed position. For removal or retrieval of tree cap (28) from the installed position on subsea tree hub (10), fluid pressure is applied through fluid lines (108, 110) for the upward movement of seal plate (68) and tubular seal members (70, 72) from sealing relation with production bore (13) and annulus bore (15). Hydraulic fluid is supplied from the ROV through fluid coupling devices (98, 112) which are insertable within receptacles (110, 114) in the tree cap body (30). The fluid couplers (98, 112) are removed from the operating receptacles after installation of the tree cap (28) and are parked in other receptacles on a tree frame until needed for further service ,such as removal of the tree cap (28). A spare tree cap may be positioned on the tree frame and installed on the tree hub by the ROV.