ONGC moves two deepwater rigs to KG-DWN-98/2

Vol 9, PW 17 (01 Dec 05) Exploration & Production

ONGC has decided to move its two hired deepwater drillships Discoverer Seven Seas and Belford Dolphin to eastern offshore block KG-DWN-98/2, where former operator Cairn Energy still holds 10%.

Both drillships recently drilled one dry hole each in the eastern offshore as part of ONGCs ongoing 37-well deepwater drilling programme. On 21st November, Discoverer Seven Seas finished the well at KG-DWN-98/4 where she was sitting in 800 metres water and drilled to a depth of 3779 metres.

There were no shows at all, reveals a source. The well was dry and ONGC decided against testing.

One positive outcome from this well was that, drilling was free of any mishaps even though the weather was quite bad with cyclonic storm conditions early and in mid-November. ONGC originally wanted to move Discoverer to the Cauvery basin but eventually decided to re-locate the rig to the more prospective KG-DWN-98/2, hoping to end its current drought of dry wells.

When it was operator with 100% interest at KG-DWN-98/2 Cairn carried out an extensive seismic survey over the block and finalised a number of drilling locations all of which are now available to ONGC. Before Discoverer moves to KG-DWN-98/2 she will undergo routine maintenance checks and repairs to her dynamic positioning system.

The repairs are not major and will be carried out on board, at sea itself, says a source. Discoverer has been assigned location A-1 in about 800 metres water at KG-DWN-98/2 and is scheduled to drill to target depth of 2600 metres to reach Pliocene era sediments in Godavari clays in a 25-day drilling programme.

Industry sources say the A-1 structure is of moderate prospectivity but is similar to the structure at ONGCs nearby G-4 location where it announced a medium-sized discovery. A-1 lies down dip of G-4, we hear, It is likely to be a fan structure.

The sands may or may not be stacked.