Abstract: A jack-up rig for offshore operations comprises a hull. In addition, the rig comprises a support leg moveably coupled to the hull. The support leg has a central axis, an upper end, and a lower end opposite the upper end. Further, the support leg is adapted to be axially raised and lowered relative to the hull. The rig also comprises a ballast tank movably coupled to the support leg. The ballast tank is adapted to be axially raised and lowered relative to the support leg and the hull.

Abstract: A method for monitoring a leg of an oilfield platform, the platform having a plurality of legs, each leg with a plurality of chords, each chord with a corresponding rack, the platform including a rack-and-pinion leg jacking system with a motor and gear system with pinions for jacking the legs up. The method, in certain aspects, including providing a load monitor with a strain sensing apparatus on a selected pinion of each rack-and-pinion system, providing a rack path differential monitoring system for monitoring rotation of the selected pinions to provide an indication of a linear displacement of the selected pinions for comparison to indicate rack path differential for racks of the legs of the platform.

Abstract: A method for monitoring a leg of an oilfield platform, the platform having a plurality of legs, each leg with a plurality of chords, each chord with a corresponding rack, the platform including a rack-and-pinion leg jacking system with a motor and gear system with pinions for jacking the legs up. The method, in certain aspects, including providing a load monitor with a strain sensing apparatus on a selected pinion of each rack-and-pinion system, providing a rack path differential monitoring system for monitoring rotation of the selected pinions to provide an indication of a linear displacement of the selected pinions for comparison to indicate rack path differential for racks of the legs of the platform.

Abstract: A method for monitoring a leg of an oilfield platform, the platform having a plurality of legs, each leg with a plurality of chords, each chord with a corresponding rack, the platform including a rack-and-pinion leg jacking system with a motor and gear system with pinions for jacking the legs up. The method, in certain aspects, including providing a load monitor with a strain sensing apparatus on a selected pinion of each rack-and-pinion system, providing a rack path differential monitoring system for monitoring rotation of the selected pinions to provide an indication of a linear displacement of the selected pinions for comparison to indicate rack path differential for racks of the legs of the platform. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope of the invention, 37 CFR 1.

Abstract: A sheave block for use with a wireline includes first and second opposing walls and a shaft extending therebetween. At least one grooved sheave is disposed on the shaft, each sheave being engageable with the wireline. At least one retractable sheave guard is movably connected to the first and second opposing walls and is moveable between open and closed positions, the open position allowing the wireline to be rereeved around at least one of the grooved sheaves without entirely removing the wireline from the sheave block.