Acoustically Linked, Remotely Operated Vehicle Deployable, Subsea VIV Measurement System on XVIII: Development, Testing, Deployment and Results.

Abstract

In August 1998, a 10-inch Steel Catenary Riser (SCR) was installed on the Petrobras XVIII semi-submersible production platform, moored in 910 meters water depth in the Marlim field, Campos Basin, offshore Brazil [1]. This was the first SCR ever installed on a floating moored platform.In order to evaluate and verify the methodologies and to calibrate the numerical models used in the riser, mooring system and platform design, it was necessary to establish a monitoring program for all the relevant parameters (environmental, platform positions and motions, riser loads and stresses at the top and at the touch down point (TDP) and vortex induced vibrations) [2]. The TDP monitoring system was described in Edwards 1999 [3]. In February 2000, the Vortex Induced Vibration Monitoring System (VIVMS) was added for measuring and recording vibrations of the SCR induced by flow and by the motions of the semi-submersible platform P XVIII. This paper describes the VIVMS, which was developed to measure, at up to four locations along the SCR, accelerations in three orthogonal directions and angular rates in two directions. The system records this information locally in subsea enclosures, transmits it to the surface on command and includes the software to transform the riser fixed accelerations and rates to earth fixed linear and angular velocities and displacements.