April 11 (Bloomberg) -- Reliance Industries Ltd. and Oil & Natural Gas Corp. are among Indian oil and gas explorers losing offshore rigs as rivals such as Saudi Arabia, Nigeria and Brazil step up efforts to drill wells in deep waters.

The number of rigs operating off India slipped to 25 in March from 31 a year earlier, U.S. oilfield services provider Baker Hughes Inc. said in a monthly report on its Web site today. Saudi Arabia almost doubled its rig count to 13 from seven, while the number in use off Brazil's coast rose by three to 26.

Rising exploration spending and record oil prices have kept deepwater rigs operating near capacity for two years, and tripled rig rentals, according to Houston-based rig consultant ODS-Petrodata. In February, India was the largest offshore rig user in the world after the U.S.

``There is a shortage of deepwater rigs worldwide,'' Tony Regan, a consultant for U.S. Nexant Ltd., said in Singapore.

Explorers added just two rigs globally in offshore areas in March compared with a year earlier, reflecting the tight market for drilling equipment, Baker Hughes said.

There were 285 offshore rigs in use last month. That's 27 percent of the total drilling for oil and gas in water and on land across the globe. The Asia-Pacific region accounted for 106 offshore rigs.

Saudi Arabia will start adding 500,000 barrels a day of oil to its total capacity when the Khursaniyah field comes on stream this month, an official at state-run oil company Saudi Aramco said on April 9. Aramco will add a further 250,000 barrels a day by the end of the year from its Shaybah oil field expansion.

India's greatest need is for rigs that drill in water depths of as much as 10,000 feet (3,050 meters), V.K. Sibal, the nation's oil and gas regulator, said last month.

Reliance is counting on offshore drilling to produce as much as 80 million cubic meters of gas a day in India in 2009, about 20 percent below than the country's current gas consumption, to meet a supply shortfall.

Discoverer Seven Seas and Deepwater Expedition, two deepwater rigs rented by Oil & Natural Gas and Reliance respectively, were taken off from operations in February for maintenance along with Oil & Natural Gas's E. Thornton, a shallow-water driller, owner Transocean Inc., the world's biggest offshore drilling contractor, said on its Web site.

Actinia, hired by Reliance, was sent to the yard in March and F.G. McClintock, rented by Oil & Natural Gas, will go for repairs this month, Transocean said.

Deepwaters, where advanced drilling rigs operate, is typically classified as depths beyond 3,000 feet. Jackups, which are so named because they rest on retractable legs that extend to the seafloor, are designed to drill in less than 400 feet of water.

To contact the reporter on this story: Dinakar Sethuraman in Singapore at dinakar@bloomberg.net.

Last Updated: April 11, 2008 00:25 EDT