An offshore platform lifting device for lifting operations at sea after sailed to a certain position of a sea surface includes an upper deck, a plurality of upright columns, a rail seat, a base disposed on the rail seat, two davit arms, two first winches, and two second winches. The upper deck has a lower pontoon. The upright columns are connected between to the upper deck and the lower pontoon. Each upright column is provided with a support leg that is longitudinally inserted through the upright column, thereby positioning the offshore platform lifting device on the seabed through the upright columns. The two davit arms are disposed the base and drives the base to move laterally through a pushing device. The two second winches each have a second cable passing through the two davit arms. A hook is disposed at a distal end of the second cable.

Provided is an offshore structure, especially offshore wind turbine, including a platform that is connected to the seabed, especially via a foundation that carries the platform, and an appliance, wherein it comprises guiding means for guiding at least one tube or cable along a guidance path from a respective entry point at which the tube or cable enters the platform to a respective connection point at which the tube or cable is connected or connectable to the appliance.

An offshore platform lifting device for lifting operations at sea after sailed to a certain position of a sea surface includes an upper deck, a plurality of upright columns, a rail seat, a base disposed on the rail seat, two davit arms, two first winches, and two second winches. The upper deck has a lower pontoon. The upright columns are connected between to the upper deck and the lower pontoon. Each upright column is provided with a support leg that is longitudinally inserted through the upright column, thereby positioning the offshore platform lifting device on the seabed through the upright columns. The two davit arms are disposed the base and drives the base to move laterally through a pushing device. The two second winches each have a second cable passing through the two davit arms. A hook is disposed at a distal end of the second cable.

An offshore structure includes an original structure and an extension structure. The original structure includes a main platform supported via a foundation on a seabed. The extension structure includes a platform extension positioned laterally of the main platform and a platform extension support, depending downwardly from the platform extension, into contact with the foundation, so as to support the extension structure directly on the foundation.

Techniques and devices to assist an offshore unit in going on location and coming off location. A device may include an interface configured to receive a signal indicative of motions of an offshore unit. The device may also include a memory configured to store a set of values corresponding to acceptable motions of the offshore unit, as well as a processor configured to determine if a measured motion of the offshore unit exceeds at least one value of the set of values and generate an indication that going on location by the offshore unit can be undertaken when the processor determines that the measured motion of the offshore unit is less than or equal to the at least one value.

Exemplary inventive practice provides a structure that is attributed with superior resistance to loading. For example, an inventive structure includes two coaxial axisymmetric (e.g., cylindrical) shells and a granulation-filled matrix material occupying the peripheral space between the shells. According to some inventive embodiments, the granulation-filled matrix material has a loading-responsive matrix (e.g., shear-thickening fluid or highly rate-sensitive polymer) and granules dispersed therein. When the inventive structure encounters pressure loading at its exterior shell, the consistency of the loading-responsive matrix becomes thicker or firmer and thereby promotes, among the granules, interactive mechanisms (e.g., friction and/or arching) that reinforce the granulation-filled matrix material. According to some inventive embodiments, the granulation-filled matrix material has a magnetic-field-responsive matrix and magnetizable granules dispersed therein, and is magnetically fortified via application of a magnetic field (e.g., continuously applied where the matrix is magnetorheological fluid, or temporarily applied where the matrix is rheological fluid containing diamagnetic particles).

A method to manufacture a platform for offshore installation by determining one or more properties selected from a group consisting of a desired length, a cargo tonnage requirement, a heavy lift capacity, total buoyancy, and an operating depth of the platform, and designing a hull section, a first jack up rig, and a second jack up rig based on the determined properties. The first designed jack up rig is joined to a first end of the designed hull section, and the second designed jack up rig is joined to a second end of the designed hull section located opposite the first end.

A semi-submersible support platform and a positioning method thereof are disclosed. The semi-submersible support platform, used for operations at sea after sailed to a certain position of a sea surface, includes an upper deck and a lower pontoon. The upper deck and the lower pontoon are connected by a plurality of upright columns. Each upright column is provided with a support leg that is longitudinally inserted through the upright column. The lower pontoon has a plurality of chambers for receiving water therein. The support leg has a compartment for receiving water therein. Each upright column includes a leveling mechanism therein. When the support leg sinks to reach the seabed, the leveling mechanism in each upright column is combined with the support leg to support the support leg. The leveling mechanism can drive the upper deck to move up or down along the support leg.

A first permissible operating range of the self-elevating vessel is determined based on a first structural analysis of the self-elevating vessel under a first set of conditions. A structural utilization ratio of the self-elevating vessel is determined based on a second structural analysis of the self-elevating vessel under first and second sets of conditions. Safety of lowering the self-elevating vessel from an elevated state to a first hull draft level is determined when the structural utilization ratio is less than a predetermined value. Safety of lowering the self-elevating vessel from the first hull draft level to a second hull draft level is indicated when positional displacement data obtained while the vessel is at the first hull draft level indicates that the positional displacement of the self-elevating vessel while at the first hull draft level is within the first permissible operating range.

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.