How Shell uses technology to find oil fields and monitor drilling

In the wake of the Deepwater Horizon disaster in the Gulf of Mexico in April 2010, drilling in the deep waters of the Gulf was halted.

Now, slowly, activity is resuming - including at Perdido, the world's deepest drilling and production platform. Operated by Shell, it lies 200 miles out into the Gulf, off the coast of Texas.

Our Industry correspondent John Moylan went to Shell's Real Time Operating Centre in Houston, to find out about the technology the company uses to find oil fields - and to monitor drilling safely.