McDermott completes works on Vashishta and S1 for ONGC

McDermott concludes the installation and startup on the Vashishta and S1 gas field in the Krishna-Godavari basin off India for Oil & Natural Gas Corporation (ONGC).

The Vashishta field lies in water depths varying between 500 and 700 meters and approximately between 31 to 35 km from the Amalapuram coast. The S1 field is located in water depths of between 250 to 600 meters.

The ONGC development encompasses drilling, re-entry and completion of three wells, subsea tie-back of the wells to an onshore terminal at Odalarevu and expansion of the existing onshore terminal.

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 of umbilicals. The pipeline scope includes 93 km of 14-inch dual rigid pipelines extending from the shallow water shore line to a maximum water depth of 700 meters.

“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.

The Vashishta field is estimated to produce 9.56 billion cubic metres (bcm) over a period of nine years with peak production reaching 3.55 million metric standard cubic metres a day (mmscmd) during the first five years. The S1 field is expected to deliver 6.22bcm over a period of eight years with a peak production of 2.2mmscmd for the first five years.