Background

ROV Construction and Survey

Background

The project was located in the Santos Basin of Brazil approximately 167 nautical miles offshore. Project water depth ranged between 2,140 metres and 2,220 metres. A five to seven man survey team was required for a duration of nine months.

Background

Solution

WROV systems were fitted with ROVINS inertial navigation systems to improve position accuracy and stability at depth. Each ROVINS was aided with USBL, LBL, DVL and digiquartz inputs. Proserv designed and provided bespoke ROVINS cabling to simplify sensor interfacing. A DVL splitter cable allowed the DVL PD13 output to be split subsea. This provided a feed directly to the ROVINS while maintaining the input to the ROV control system.

After in-field calibrations the units were proven to provide the expected three times improvement on USBL accuracy. Systems were verified using LBL arrays. Eight Sonardyne 6G LBL arrays were installed and calibrated by Proserv field staff. Array analysis was performed in Geoline 3D during the project planning phase to assess the seabed ranging that could be expected in the field. Cut to length and drill centre arrays were required to support the pipeline and free standing hybrid riser installations. Upon completion of LBL array calibrations, WROV tracking trials were conducted to ensure the arrays were functional.

Scope

The project scope of work included:

  • Provision, interfacing and set-up, and calibration of survey equipment
  • LBL array deployment, calibration and operation
  • Pre-lay surveys
  • Survey installation support for risers and structures
  • Touchdown monitoring for risers
  • As-laid surveys and as-built surveys

Vessel equipment included:

  • Veripos Ultra DGNSS
  • iXBlue HYDRINS
  • Seapath 200 heading system
  • Kongsberg HiPAP 500

LBL equipment included:

  • Sonardyne DFE
  • 6G dunker
  • Sonardyne iWand DTU
  • Sonardyne 6G RTP & SVS Compatts
  • Seabed frames & collars

WROV equipment included:

  • Sonardyne 6G ROVNAV
  • Valeport Midas SVX2
  • Paroscientific 8CB4000 depth sensor
  • Reson 7125 MBES dual-head system
  • TSS440 pipetracker
  • iXBlue ROVINS
  • RDI WN-1200 doppler velocity log
  • MacArtney Nexus MK4 multiplexor
  • Paroscientific 8CB4000 depth sensor
  • Imenco green laser
  • Hydraulic rams for ROVNAV
  • Wheeled undercarriage
Background

Conclusion

The LBL arrays were installed, calibrated, operated and maintained over the nine month project duration without lost time due to Survey Services personnel.

“I would definitely recommend Proserv; an excellent job performed.”

Saipem 2014

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