Survey & Positioning Services

Technical Cont.

For precise positioning of jack-up drilling rigs over existing subsea wells MOD has developed its own well-proven “RigFix” equipment. This system incorporates the MEL Scout 2 acoustic positioning system with purpose-designed MOD acoustic rigmove software called “Accurig-Acoustic”. Transducers are installed in coordinated locations on the three rig legs and a transponder is located at the wellhead. The three transducers transmit in turn to the transponder, which replies to each transmission. Thus each range is measured three times in each cycle and the ranges are majority-voted and meaned for quality control.

For close-tolerance rigmoves adjacent to existing platforms, MOD use combinations of autotracking or reflectorless Leica total stations, located in measured positions on the rig’s transom, ranging to pre-installed prisms or coordinated platform detail.  These provide precise multi-bearings and distances to MOD’s own “Accurig-EDM” software. The program allows the rig to be very accurately emplaced with the required derrick skid offsets to be observed online.

To assist with general rigmove requirements, MOD also own numerous survey quality gyrocompasses including fibre-optics units capable of fitting into underwater housings, theodolites, levels, temperature / salinity sensors, radio telemetry systems and current meters etc.

A CAD drafting service is provided to enable client rigmove planning and provide quality control and background monitor images for our rigmove screens offshore.

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