ONGC examines technology to cut deepwater costs

Vol 7, PW 23 (11 Feb 04) Exploration & Production
     

Deepwater drillers take note: ONGC is ready to experiment with a new advanced and cost-effective deepwater drilling technology that may put you out of business, at least in India.

In October later this year, ONGCs Sagar Bhushan rig will drill into deepwater depths much beyond its 400 meters capability with the help of submerged buoyant tank technology called Artificial Buoyant Seabed (ABS). On 23rd January, ONGCs chief of drilling services UN Bose made a presentation on this concept at a meeting of the International Association of Drilling Contractors.

The ABS concept can cut ONGCs deepwater drilling day rates by at least 50% because it enables rigs without any deepwater specialisation to drill in deep and ultra deep waters, ONGC tells PETROWATCH. If the ABS concept succeeds, it would boost ONGCs deepwater programme both technically and financially.

According to the official, if ONGC is paying a day rate of $360,000 for services, including offshore drilling, field development and production, its expenses could be lowered by as much as $100,000 per day by using the ABS technique. Once the ABS is installed there is no need to run the BOP and the drilling riser through the water column to the seabed, he adds.

This will save rig time of more than seven days. More, this concept allows the use of a 2nd or 3rd generation rig in combination with a taut-leg polyester mooring system instead of a high rated drilling unit, believes ONGC.

The concept is based on the simple principle of extending well casings upwards from the seabed to the ABS, where the Blow Out Preventor and subset wellheads are located. Typically, the ABS would be located 200-300 metres below water.

In this way a subset platform is established at a shallow water depth for installation of drilling and production equipment. ONGC believes that with the help of this concept, rig operations could be carried out quicker in deep and ultra deep water by using shallow water rigs and equipment that it already has available.