UPDATE 1-Transocean second-quarter profit doubles

(Recasts, adds analyst estimate, details)

HOUSTON, Aug 6 (Reuters) - Transocean Inc (RIG.N), the world's largest oil and gas drilling contractor, said second-quarter profit doubled, topping Wall Street estimates, on strong demand for its offshore rigs.

Transocean has seen rates for certain deepwater rigs top $600,000 per day as high crude oil prices prompt demand from exploration and production companies. Tight rig supplies have also helped push contract awards higher.

Second-quarter profit rose to $1.1 billion, or $3.45 per share, from $549 million, or $2.63 per share, a year earlier.

Analysts on average had expected a profit of $3.30 per share, according to Reuters Estimates.

Revenue more than doubled, soaring to $3.1 billion.

The average daily rate paid for Transocean's drilling fleet rose 18 percent from a year earlier to $238,600 as contracts were renewed at higher rates. (Reporting by Anna Driver; editing by John Wallace)