McDermott completes installation, startup for Vashishta and S1 field

CHENNAI, India -- McDermott International, Inc., has successfully concluded the installation and startup on Vashishta and S1 field, an engineering, procurement, construction and installation (EPCI) contract that it received from ONGC in December 2015.

McDermott, together with consortium partner LTHE, a wholly owned subsidiary of Larsen & Toubro Limited (L&T), was responsible for the 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 km (30 mi) of umbilicals. The pipeline scope includes 93 km (58 mi) of 14-in. dual rigid pipelines extending from the shallow water shore line to a maximum water depth of 700 m (2,300 ft).

“I’d like to take this opportunity to congratulate ONGC in achieving this important first gas milestone! The success of this project confirmed that our consortium with LTHE has performed well in delivering the best in-market solution for our client," said Ian Prescott, McDermott’s V.P. for Asia. "We look forward to building on this strategic collaboration for future projects in India.”

“Engineering design for the Vashishta project was no easy feat, due to the iterative nature of the design process which had to reconcile many factors such as soil conditions, jumper/spool loads, connector capacities, in-place environmental loads, pipeline expansion loads, installation weather limitations, vessel envelope constraints and mission equipment constraints,” said Ben Delves, McDermott’s Vashishta project director.

Typical weights for Vashishta PLETs and ILTs ranged from 35 to 85 metric tons (27 to 93 tons) and the PLEM weight was 200 metric tons (220 tons).  "A combination of soft soils and the significant weight of permanent equipment has contributed to some large structures which made the interfaces with the installation vessel challenging," said Delves.

The installation of the subsea infrastructure was particularly challenging as McDermott only had four months out of the year to work at the Krishna-Godavari basin before the monsoon season hit the field with bad weather and strong sea undercurrents.

McDermott deployed three of its specialty vessels to complete the installation phase, namely Derrick Barge 30, Lay Vessel North Ocean 105 and North Ocean 102.  McDermott also deployed its trademarked portable spoolbase at the LTHE base in Kattupalli, India, to fast-track the production of pipeline stalk for loading onto the installation vessels.