Patent ID: 7878735

Claim:
A marine pipelaying system for vertical or near vertical laying of an offshore pipeline, wherein the system comprises: a. a drilling vessel comprising an upper deck structure through which a moonpool extends, a lower deck structure and a vertical drilling structure associated with the moonpool, wherein the vertical drilling structure is adapted for drilling operations through the moonpool, and wherein the vertical drilling structure is adapted as a pipe section holder for holding a pipe section in an essentially vertical orientation; b. a drilling hoist connected to the vertical drilling structure, wherein the drilling hoist comprises a cable and a winch for raising and lowering a drill string; and c. a pipe laying apparatus provided below the vertical drilling structure, wherein the pipe laying apparatus comprises: (i) a main supporting structure mounted on the lower deck structure below the upper deck structure; (ii) a pivotable structure that is supported pivotably by the main supporting structure; (iii) a static clamp arranged within the pivotable structure, wherein the static clamp is adapted to releasably secure an uppermost end of a previously launched pipeline, and wherein the static clamp is adapted to support a weight of the previously launched pipeline; (iv) a mobile clamp adapted for releasably securing the previously launched pipeline at a position below the static clamp, wherein the mobile clamp is adapted to support the weight of the previously launched pipeline as the previously launched pipeline is released from the static clamp; (v) a mobile clamp hoist comprising: at least one mobile clamp supporting cable for supporting the mobile clamp, and at least one mobile clamp winch for raising and lowering the mobile clamp and the previously launched pipeline, wherein the main supporting structure is slidable with respect to the lower deck structure between an operational position in which the pipe laying apparatus is in line with the previously launched pipeline to affect pipelaying through the moonpool, and a non-operational position on the lower deck structure adjacent the moonpool, wherein in the non-operation position drilling operations are performed through the moonpool, and wherein the pipe laying apparatus is moveable both with respect to the moonpool and with respect to the vertical drilling structure.