India, one of the world’s largest and fastest growing economies, is on course to becoming the leading consumer of energy by 2035. Its thirst for energy will be defined by natural gas – expanding at about 1.6% per year it will grow faster than both oil and coal. In its bid to cater to this upcoming demand ONGC, country’s largest producer of crude oil and natural gas has embarked on an ambitious plan that entails exploration of deepwater opportunities in the Krishna Godavari Basin off the east coast of India. Specifically, the Maharatna Company has set its sight on the Vashishta and S1 fields in the basin which hold vast gas reserves in waters 700 meters deep.
Subsea Installation of Vashishta & S1 Development Project was conceptualised by ONGC on EPCIC (Engineering, Procurement, Construction, Installation and Commissioning) basis to tap the unexplored gas reserves off the east coast of India. On December 1, 2015, it awarded the project to a consortium of L&T Hydrocarbon Engineering Limited (LTHE), a fully owned subsidiary of L&T and McDermott International (McDermott) after a round of intense international competitive bidding.
The partnership between LTHE and McDermott offered a value proposition that no other vendor could. Having signed a long-term agreement to execute subsea projects on the east coast of India, LTHE and McDermott brought a cost-effective approach utilizing LTHE’s state-of-the-art, strategically located Modular Fabrication Facility in Kattupalli (MFF-K), Chennai. Besides a spool base to support deepwater pipelay that was setup at MFF-K, the facility also boasts of expertise in manufacturing critical subsea components deployed to collect and transport fluids from the seabed to shore. This combined with the versatile fleet of McDermott was enough for ONGC to entrust the consortium with the job.
A Colossal Scope
Deepwater development projects are every bit as challenging and complex as they sound. The deepwater Vashishta & S1fields are envisaged to produce and deliver 4.55 MMSCMD of gas through twin subsea pipelines to the onshore terminal. The infrastructure on the seabed includes a number of subsea structures which are used to collect and transfer well fluids to the twin pipelines. With no scope of human intervention at these water depths, all the controls for production system are through electro-hydraulic umbilicals installed on the seabed and linked to the control room onshore. These systems have to be designed to endure the harsh environment in these waters for 20 years.
The Vashishta field comprises two wells (VA-DA and VA-DB) and is located in water depths of 500 to 700 meters. The S1 field comprises two wells (S-2AB and S-AC) and is located in water depths of approximately 250 to 420 meters. The onshore processing terminal at Odalarevu is located at about 90 km to the south-east of Rajahmundry.
The scope for the project covered Surveys (pre-engineering, pre-construction/pre-installation and post-installation), Design, Engineering, Procurement, Fabrication, Load out, Tie down/Sea fastening, Tow-out/Sail-out, Transportation, Installation, Hook-up, Testing, Pre-commissioning and commissioning of entire facilities for the following:
a) Laying of 14” dual rigid pipelines from Odalarevu Onshore Terminal to VA-DA (2 x 14” x 42.7 km approx., of which approx. 7 km in onshore) and from VA-DA to VA-DB (2 x 14” x 4.4 km approx.)
b) Pipeline End Manifold (PLEM) near VA-DB
c) Procurement and installation of Production Umbilicals and Infield Production Umbilicals
d) Installation of subsea control units like Subsea Distribution Units (SDUs), Umbilical Termination Assemblies (UTAs), Umbilical Termination and Distribution Assemblies (UTDAs)
The infrastructure on the seabed comprised Inline Tees (ILTs), Pipeline End Terminations (PLETs), Pipeline End Manifold (PLEM), PLET / PLEM tie-in spool pieces, Wellhead tie-in spool pieces and Pipeline crossover spool pieces.
An Impossible Deadline
The consortium was to execute the project in 20 months, a nearly impossible deadline considering the nature and the scale of the development. The gruesome schedule, if it was to be met, required precise planning for all deliverables including long lead items such as corrosion and concrete coated linepipes and subsea valves. The east coast which is prone to cyclones and rough weather also offered an extremely limited window of four months for offshore installation.
Precise engineering from McDermott’s design office in Kuala Lumpur, quick resolution of interfaces by LTHE and McDermott Project Management Teams and swift coordination among various stakeholders spread across different geographies was of paramount importance. Concurrent engineering and ensuring that work fronts were available to Procurement and Fabrication teams was also key to beating the clock and delivering the project on time.
Procurement timelines are always crucial for project schedule. In order to complete the fabrication and subsequent installation on time, delivery of materials at fabrication yard is extremely crucial. Vashishta & S1 Development Project saw orders being placed for two critical packages within a fortnight from project award date. This included pipelines by LTHE and umbilicals by McDermott. Another critical item for meeting the project schedule was complicated subsea valves which were delivered on time after expeditious engineering interface resolution and close coordination with the vendor. Orders for all other critical and long lead items were placed expeditiously leveraging LTHE and McDermott’s vast vendor base spread across the globe.
Fabrication – Zero Punch Points
Subsea structures which are intended to have Remotely Operated Vehicle (ROV) interventions need to be manufactured with high precision and tight tolerances to sustain for design life of 20 years. Moreover, the timeline for fabricating all the subsea structures and rigid jumpers in less than 10 months along with rigorous testing compounded the challenge. These intricacies required engagement of high-end services such as three dimensional survey and specialized processes associated with small bore tubing.
All the fabricated structures underwent a series of tests as part of the Factory Acceptance Test (FAT) and System Integration Test (SIT) wherein subsea conditions are simulated on shore to assess the functionality of the system. ROV operability was also checked during the testing phase to make sure that the structures were installed in one go without the need for any re-work or re-intervention.
Meticulous planning, engineering, synchronized teamwork and skilful coordination meant that all the structures were ready ahead of schedule for sail out without any punch points.
Portable Spoolbase – A First for India
The Project involved setting up of a portable Spoolbase at LTHE’s MFF-K Yard, a first for Indian shores. The Spoolbase was set up on a stretch of land 1.2 km long and 35 m wide. This space was used to spool individual line pipes measuring 12.2 m each into a 977 m long pipe which was later reeled / spooled onto a carousel mounted on McDermott’s reel-lay vessel North Ocean 105. The unique pipelay methodology enabled the consortium to install pipelines and structures in deepwaters against rough weather conditions in a short span of time. Any conventional pipelay process would have found these conditions unsuitable for completion of the project in the scheduled period.
Loadout, Transportation & Installation
Marine logistics engaged for Vashishta & S1 Development Project was far-reaching with number of survey vessels, installation vessels and supply boats deployed for the project. Fabricated subsea structures were loaded out onto supply vessels from Kattupalli and transported to the field for installation. Offshore installation was carried out in a phased manner which began with installation of concrete and corrosion coated linepipe and main production umbilical in shallow water followed by deepwater linepipe along with the fabricated subsea structures and finally control systems which included the rigid jumpers and in-field umbilicals.
In addition to the offshore installation, the scope also involved the onshore installation of approximately seven kilometres of twin pipelines and 3.5 kilometres of umbilical. These onshore pipelines and umbilical were tied to the respective offshore segments at the landfall point and inside the onshore terminal on the other end. The onshore terrain for installation offered its own set of challenges which were overcome by engaging agencies which had prior experience in the field. The pipelines post installation were successfully tested and pre-commissioned to the client’s satisfaction.
The Vashishta & S1 field development project adds another dimension to the Make in India program, combining McDermott’s global expertise with LTHE’s manufacturing capabilities – ensuring that the bulk of the project execution took place in India.
Like the intended goal of the project which aims at ensuring greater energy security for the country, LTHE’s bolstering of its deepwater capabilities equips India in terms of local capabilities. Oil & Gas firms no longer need to look westward to explore the natural energy resources hidden deep in our seas. LTHE has it covered!
