Riser Position Reference System

The Riser Position Reference System (RPR) is an independent position reference system for dynamically positioned drilling vessels. RPR is an extension of the Riser Management System (RMS).

Immediately after latching the BOP onto the wellhead, the RPR will be calibrated against other position available references (e.g. GPS or HPR). Following a short calibration period, the vessel can be positioned based on the RPR system. RPR provides redundancy to the position keeping and thereby enhances the safety of deep-water drilling operations.

The RPR is a separate software module interfaced to the Kongsberg Maritime DP system. RPR utilises the riser joint properties, riser model and sensor calibration data provided by the RMS.

Measurements of riser top and bottom inclinations, riser top tension and mud weight are input to the RPR.  

The RPR continuously updates the position estimate based on the input measurements by means of a dynamic model of the vessel- riser system and Kalman filter technique. Measurement of top and bottom angles and tension forms basis for position estimate.

Knowledge of the physical properties of the riser, enables build-up of a computer model of the complete riser. During the initial phase of estimating, the model is “calibrated” online and a current model is established.

A prototype of the RPR is installed and used onboard the drill ship Saipem 10000. Saipem, Statoil and Norsk Hydro have supported the development project.