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.

The offshore jack-up has a hull and a plurality of moveable legs engageable with the seafloor. The offshore jack-up is arranged to move the legs with respect to the hull to position the hull out of the water. The method comprises moving at least a portion of a vessel underneath the hull of the offshore jack-up or within a cut-out of the hull when the hull is positioned out of the water and the legs engage the seafloor. A stabilizing mechanism mounted on the jack-up is engaged against the vessel. The stabilizing mechanism is pushed down on the vessel to increase the buoyant force acting on the vessel.

The present invention generally relates to a continuous monitoring system and method for monitoring the loads in a support leg of an offshore drilling rig through a remote unit mounted to the climbing pinion shaft of a jacking drive system when the brake is engaged.

The offshore jack-up has a hull and a plurality of moveable legs engageable with the seafloor. The offshore jack-up is arranged to move the legs with respect to the hull to position the hull out of the water. The method comprises moving at least a portion of a vessel underneath the hull of the offshore jack-up or within a cut-out of the hull when the hull is positioned out of the water and the legs engage the seafloor. A stabilizing mechanism mounted on the jack-up is engaged against the vessel. The stabilizing mechanism is pushed down on the vessel to increase the buoyant force acting on the vessel.

A system is disclosed including but not limited to a a jack up processor in data communication with each for dynamically balancing loads in real time on a plurality of legs supporting a jack up rig platform having a plurality of gear box motors on the plurality of legs. A processor reads data from sensors on gear box motors on the legs and selects a stored torque profile from a computer readable medium based on the load data from the sensors; and sends the torque profile to the plurality of gearboxes. A computer readable medium and neural network are disclosed for dynamically balancing loads on the plurality of legs in real time.

A measurement system that comprises at least one horizontal load measuring unit, that is preferably arranged on the leg guide is provided. The horizontal load measuring device measures or determines horizontal load on the position of the leg where the device is placed, which gives a more accurate indication of the leg bending moment than the rack phase differential measurement. Advantageously, multiple load measuring units can be provided along the leg guide.

A method for abandonment of a production platform includes moving a mobile offshore service platform (MOSP) to a position proximate the production platform. A hull of the MOSP is raised to a selected elevation above a top of the production platform. A cantilever structure having thereon a drilling unit and a crane is extended from a retracted position over the hull until the drilling unit is positioned over at least one well on the production platform. The well is plugged. The cantilever structure is then moved so that the crane is positioned to lift components from the production platform during disassembly of the production platform.

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 system is disclosed including but not limited to a jack up processor in data communication with each of one of a plurality of gearbox motors over a first unidirectional data link for sending speed reference data to the plurality of gear box motors on the jack up rig leg to raise and lower a jack up rig leg; and a second unidirectional data link for load data from a sensor on each one of the gear box motors at the controller from the plurality of gearbox motors on the jack up rig leg. A method is disclosed for using the system.

A gear pair for a lifting vessel includes two gear units driving in opposite directions of rotation and configured for engagement in two tooth racks on a jack-up leg, respectively. Each gear unit includes a drive shaft for connection to a drive, an output shaft for connection to a drive pinion, a transmission housing, a planetary stage mounted in the transmission housing, and a torque support configured to enable support of the gear unit on the other gear unit. The torque support surrounds the transmission housing of the other gear unit in a pincer-like manner and contacts the transmission housing symmetrically with respect to a straight line connecting the output shafts of the gear units at two support points which in relation to a vertical plane extending through the output shaft of the other gear unit are located offset towards the gear unit having the torque support.