Modus wraps up Vashishta field work

Subsea engineering specialist Modus Seabed Intervention has completed work on the ONGC Vashishta pipelines and umbilical offshore India for McDermott International.

Modus said on Thursday that the scope included the trenching and surveying of two 18-kilometer long pipelines with outside diameters of up to 579 millimeters.

The company also did work on a 24-kilometer long 284-millimeter outside diameter umbilical, down to a maximum trench depth of two meters.

The water depth for trenching operations ranged between 3.5 meters and 217 meters and involved mobilizing the Modus CT-1 trenching vehicle onto the Bourbon 807 for the deeper water sections and then transferring the trenching equipment to the Multicat Zwerver II for the shallow water operations. The CT-1 is configured to trench in water depths from 3.5 meters to 3,000 meters.

Nigel Ward, commercial director of Modus Seabed Intervention, said: “We are very pleased to have completed the trenching on this project to specification. The adaptability of CT-1 came into its own; the vehicle was modified by the technical services team at Modus to enable the successful burial of both the umbilical and pipelines in deep and shallow waters.

“To add to the challenge, the overall weight of the vehicle was reduced so that it could be accommodated by the available vessels. Mobilizing the single trenching system to perform these scopes had obvious benefits, particularly to a location with remote support facilities.”

The Vashishta field is located 30-35 km off the Amalapuram coast in the KG Basin, off the East Coast of India, at water depths of 250 to 700 meters.

ONGC started commercial production from the field through its Onshore Gas Terminal Plant in April.

Later that month, McDermott and its consortium partner LTHE completed engineering, supply, and installation of a series of pipeline end terminations (PLETs) and in-line tee structures (ILTs), a pipeline end manifold structure (PLEM), rigid jumpers and approximately 50 kilometers (30 miles) of umbilicals on the Vashishta and S1 fields.