Behind the scenes at the world's deepest oil drilling and production platform
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.
Perdido is 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 has been behind the scenes at Perdido to find out how the operation works.