Climate change and the need to manage diminishing fossil fuel reserves are the two biggest challenges our planet is facing. This is where importance of renewable energy comes in picture. ONGC (Oil and Natural Gas Corporation Ltd, India) foresees this and has mandated IOGPT (Institute of Oil and Gas Production Technology), an in-house institute to carry out study for tapping offshore wind energy by installing wind turbine on the existing offshore Well Head platform/s which is on the verge of abandonment. These structures are in water depth of about 70 m. The power generated would be for captive use at offshore process/well head complexes through sub-sea cable grid.
Few wells in Western Offshore oil field of ONGC are being completed on ESPs on wellhead platforms. Power will primarily be supplied by the existing gas based turbine generators on Process Platform. The power from the planned wind turbine generator will be used in the same grid. This will proportionately reduce the gas consumption and in turn the rich contents of associated gas saved from being burnt as fuel will add to our value added products.
Projects completed earlier worldwide indicate cost of the foundation for any wind turbine in +45 m water depth may be more than US$ 1.1 million/MW; use of the existing structures in western offshore would amount to enormous savings in Project cost. The project envisaged is first of its kind.
Preliminary works like wind resource assessment study, wave study, structural analysis of existing structures, etc. are underway. This will be a demonstration project and would be used to examine the feasibility and benefits of creating a commercial deep-water wind farm.
ONGC; a key player in Indian offshore, has its presence in the offshore oil field since 1977. The western offshore field which is spread over more than 800sq.km in Arabian Sea is dotted by more than 180 satellite wellhead platforms and process platforms.
As part of secondary recovery from the existing objects of western offshore field, wells are being completed with Electrical Submersible Pumps (ESPs). Use of Submersible pumps in oil production will provide a relatively efficient form of ‘artificial lift’. By decreasing the pressure at the bottom of the well (by lowering bottom hole flowing pressure, or increasing drawdown), significantly more oil can be produced from the well when compared with natural production. The pumps are typically electrically powered for which continuous and reliable power supply will be required. This has necessitated the interconnection of process platforms with unmanned well platforms laying electrical cable grid.