McDermott Completes Installation and Startup for the Vashishta and S1 Field
Thursday 26 April 2018
McDermott International, Inc. announced it has successfully concluded the installation and startup on the 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 kilometers (30 miles) of umbilicals. The pipeline scope includes 93 kilometers (58 miles) of 14-inch dual rigid pipelines extending from the shallow water shore line to a maximum water depth of 700 meters (2,300 feet).
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.
Project Details
The Vashishta field lies in water depths varying between 500 and 700 meters (1,600 and 2,300 feet) and approximately between 31 to 35 kilometers (19 to 22 miles) from the Amalapuram coast. The S1 field is located in water depths of between 250 to 600 meters (800 to 2000 feet), and approximately between 26 to 29 kilometers (16 to 18 miles) from the Amalapuram coast. 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.
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.