SUBSEA construction work at the INPEX operated Ichthys project has been made more efficient by software provided by underwater acoustic positioning equipment manufacturer Sonardyne, the company has announced.

Sonardyne’s SensorView software allowed data gathered by an acoustic transponder mounted on Tubing Head Spools (THS) to be transmitted at high speed to rig personnel monitoring the installation operations.

The parameters measured by the transponder’s on-board sensors included heading, depth, sound velocity and inclination and meant delays previously incurred while aligning each THS to drilling templates could be substantially reduced, the company said.

Ichthys survey contractor Neptune Geomatics used a seabed array of Sonardyne Compatt 6 Long BaseLine (LBL) acoustic transponders to accurately position spud locations during the drilling and completions phase of the project as well as monitoring the installation of drilling guide bases (DGBs) as they were lowered from the surface.

The transponders were fitted with high resolution inclinometers and depth sensors were used to verify final DGB positions and inclinations following cementing of the conductor in the top hole section.

Sonardyne’s dedicated sensor monitoring software application SensorView was used to gather real-time positioning and heading information on each spool as it was being manoeuvered while trying to align each THS with the DGBs.

At Ichthys, SensorView was mobilised on one of the rigs and interfaced with a Dunker 6 transceiver which was deployed over the vessel’s side.

A Sonardyne GyroCompatt 6 was temporarily mounted on each THS and attached using a customised bracket designed to allow a remotely operated vehicle to recover the unit after each THS was installed.

Neptune Geomatics operations manager Pat Fournier said SensorView had delivered the company THS heading update rates of about one every three seconds during the drilling and completions campaign.

“This was sufficient for our surveyors to fully understand the dynamic motion of the structures and thereby reduce the time needed to land them in the correct location,” he said.