Zupt, LLC offers many innovative survey and positioning products to increase productivity for the offshore business. This includes tools for marine construction survey, dynamic positioning and deepwater drilling.

Many offshore survey and positioning operations are on the critical path of very expensive assets. Zupt, LLC focuses on changing the way we complete some of these precise operations through the introduction of next generation survey tools.

Metrology – the precise measurement of subsea connector (hub) locations to provide the data for the manufacture of an inter-connecting jumper. C-PINS has completed many offshore metrology surveys saving up to 70% of the time taken for such surveys.

Deep water precise positioning has, for years, required the expensive deployment of a long baseline (LBL) acoustic positioning system. Today through the combination of inertial navigation system with surface vessel referenced ultra short baseline (USBL) the time taken for the deployment and calibration of an LBL array can be saved for many “relative” positioning tasks by using our USBL smoothing solution. If the requirement is for precise “absolute” subsea positioning – our “real time calibration” option for the USBL smoothing system can maintain absolute positioning accuracy and quality metrics that stretch USBL to deep water survey operations that have required LBL in the past.

Should LBL type capabilities still be required at the seabed then the “Sparse LBL”  version of C-PINS reduces the need for large LBL arrays. With either one or two simple acoustic transponders deployed at the work site the combination of inertial and acoustic line of position allows for very reliable and precise positioning. The vessel spread time consumed for such tasks as buoy placement for well installation, suction pile marking and mat installation is significantly reduced saving overall project costs.

Increases in the reliability of position reference sensors for dynamic positioning have been sought for many years. Stand alone satellite delivered DGPS systems are a mainstay of this industry – but scintillation, multipath and total signal loss due to vessel components masking GPS antennas have caused DGPS outages and unplanned DP incidents. Acoustic positioning systems have also taken the place of taut wire in deeper water as the secondary (or primary in some cases) position reference sensors.

Acoustic positioning systems – SBL, LUSBL and USBL have for years provided reliable input into the DP desks when used within their limitations. Commercial pressures drive the operations of these systems into water depths and applications beyond the original design. Position jitter from USBL system in deep water cause the DP desk to reject the system. The cost to deploy an LBL array when working on locations for short periods (workover, marine construction DP vessels) as well as slow LBL update rates drive reliance on DGPS as the primary position reference sensor. Class requirements state that 3 independent position reference sensors operating from 2 different principals should be available on all DP 2 and DP 3 class vessels. Combining these conventional position reference sensors with inertial navigation systems significantly improves the reliability of the overall solution – as well as providing a higher update rate. D-PINS is a very capable implementation of such a solution, the system provides very precise heading, pitch and roll data. The system being tightly coupled to the DGPS solution can operate without any impact with just a single range to a satellite. The same applies to acoustic integration. A simple range to a beacon once every 30 seconds maintains the position solution into the DP desks. In conventional configurations either of these situations would be the cause of a DP incident – shutting down the work. In the drilling case this would instigate an unplanned disconnect – a very costly action.

One of the oldest reference sensors used in deep water drilling, both moored and dynamically positioned, has been a Riser Angle sensor. The dynamically positioned vessels will have an electrically connected (ERA) riser angle sensor. The moored drilling vessels will combine the riser angle sensor within the short baseline (SBL) or ultra short baseline (USBL) acoustic positioning system deployed on the vessel.  The ERA sensors deployed within the subsea mux control systems have had a reputation for not being reliable or accurate. Simple inclination sensors have been used that degrade in the presence of vibration. These sensors do not have the resolution required to view incremental changes in vessel position deep water.

The installation, maintenance and calibration has not been viewed from an operational perspective – they are just there and in many cases are not used. The Zupt high resolution ERA solves these problems by using high resolution, state of the art inertial sensors with high update rates. Stack heading is sensed to ensure differential riser angle across the flex joint is known with reference to either vessel North or true North.

Zupt has a wide range of sensors and capabilities for the offshore market, all developed to fundamentally improve productivity of operations saving vessel time and increasing the reliability of these operations.