A method for retrofitting a wind turbine foundation is provided. The foundation comprises a first substantially elongated pile (31) in the ground. The method further comprises: arranging a lower end of an elongated channel (41) of a second substantially elongated pile (40) around the first pile (31), wherein the elongated channel (41) extends substantially along a longitudinal direction of the second pile (40), wherein the channel (41) is configured to receive at least a portion of the first pile. The method further comprises lowering the second pile (40) such that the elongated channel (41) surrounds at least a portion of the first pile (31). Finally, the second pile (40) is driven into the ground (35).

An unmanned wellhead platform (1) (UWP) comprising a jacket (10) designed and adapted to be supported on the seabed and projecting above the sea level is shown. The unmanned wellhead platform (1) includes a topside installed on top of the jacket (10). The topside is designed as a standardized base concept tailored for repetitive future topside constructions (3). Each topside construction (3) is adapted to the number of wells to be developed. The topside construction (3) is made up by a number of different but standardized sections (4). Each standardized section (4) is dedicated for a particular and predetermined purpose and location in the topside construction (3).

The invention relates to a method for building concrete foundations for lattice-type offshore structures and to foundations built using this method, which has the main aim of replacing the piles used to anchor lattice structures to the seabed (7) with blocks of on-site reinforced concrete (1) which grant the necessary stability to the lattice structure (2), doing away with all pile-driving works but without performing any structural modification of said structure. Said elements (1) are positioned using templates (12). The advantages of this novel invention lie in the possibility of installation on any type of terrain, providing a perfect connection between the seabed and the foundations thanks to on-site concreting, as well as its ease of construction, reduction of noise emissions and of auxiliary means.

An offshore platform for use in combination with an offshore rig comprises an upper deck defining an upper deck aperture which is alignable with a rig aperture of the offshore rig, when said offshore rig extends over the upper deck, to permit objects to extend between the offshore rig and through the upper deck. The offshore platform further includes a sheath arrangement aligned with the upper deck aperture and extending upwardly relative to the upper deck to be alignable with the rig aperture, wherein the sheath arrangement defines a confinement zone for confining objects which pass downwardly from the offshore rig through the rig aperture.

A method includes mounting a lower platform block (300) to a plurality of piles (215) positioned on a surface. The lower platform block includes a first frame (315), a plurality of docking assemblies (305) connected to the first frame and engaging the piles, and a plurality of conductor tubes (310) connected to the first frame to a plurality of piles. The docking assemblies are released from the piles to separate the lower platform block from the piles.

An offshore structure has an upending device for upending an elongate suppo structure from a substantially horizontal loading position on a deck of the offshore structure to a substantially vertical launch position outboard of the offshore structure. The upending device has a pivot axis situated near a side of the offshore structure for pivoting the upending device between the loading position and the launch position. A first end of the upending device has a connector member for pivotally connecting to the elongate support structure. The connector member in the launch position is in a position outboard from the side of the offshore structure. A second end of the upending device is attached to a pulling device that is located on the deck of the offshore structure. The upending device is within reach of one or more hoisting means for the elongate support structure.

A pull-in head assembly (8) for releasably connecting a pulling arrangement (112) to an elongate flexible structure (4, 6). The pull-in head assembly (8) comprises a body (30) which defines a pulling axis X of the pull-in head assembly (8) and a retaining member (32) arranged around the pulling axis X. The retaining member (32) is configured to secure the pull-in head assembly (8) to an elongate flexible structure (4, 6) such that, in use, a pulling force exerted on the pull-in head assembly (8) along the pulling axis X is transferred to the elongate flexible structure (4, 6). The retaining member (32) is configured to release the pull-in head assembly (8) from the elongate flexible structure (4, 6) when the pulling force exceeds a predetermined threshold such that the pull-in head assembly (8) can be separated from the elongate flexible structure (4, 6).

A coupling system to be temporarily coupled to at least one of a jacket pile and a foundation pile comprises an upper fixation member, a lower fixation member and a lifting device for moving the upper and lower fixation members with respect to each other. The coupling system is provided with at least one of a grout transfer line for guiding grout from a grout supply to a space between a jacket pile and a foundation pile upon installing the jacket pile to the foundation pile, and a cleaning device for cleaning the inner and/or outer side of a foundation pile, and a separating device for separating a jacket pile from a foundation pile upon de-installing the jacket pile with respect to the foundation pile, and a measurement device for determining parameters of a jacket pile and/or a foundation pile.

A method of elevating the deck area of a marine platform (e.g., oil and gas well drilling or production platform) utilizes a specially configured sleeve support to support the platform legs so that they can be cut. Once cut, rams or jacks elevate the platform above the cuts. The sleeve support is then connected (e.g., welded) to the platform leg and becomes part of the structural support for the platform. In one embodiment, two sleeves are employed. In another embodiment, the jacks or rams elevate in two stages including a first stage wherein one sleeve elevates and the other sleeve does not elevate and a second stage wherein both sleeves elevate together.

A hoisting system for the installation of a wind turbine wherein said hoisting system comprises measures to achieve a load bearing connection to the tower of the wind turbine and comprises measures to move the hoisting system up and down along the tower wherein the hoisting system, when it is fixed to an already installed part of the wind turbine tower with said load bearing connection, is arranged to install or remove any of a tower segment, a nacelle, a generator, a hub, and a blade in one or more combined hoists or in a single hoist.